Office for Nuclear Regulation

An agency of HSE

Generic Design Assessment – New Civil Reactor Build

GDA Close-out for the EDF and AREVA UK EPR™ Reactor

GDA Issue GI-UKEPR-CE-02 Revision 1 –
Use of ETC-C for the Design and Construction of the UK EPR™

Assessment Report: ONR-GDA-AR-12-004

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Office for Nuclear Regulation Report ONR-GDA-AR-12-004
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First published February 2013

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EXECUTIVE SUMMARY
The Office for Nuclear Regulation (ONR), an agency of the Health and Safety Executive (HSE),
has carried out Generic Design Assessment (GDA) of the UK EPR™ nuclear power plant. Step 4
of GDA of the UK EPR™ included an assessment of the civil engineering design and the
application of external hazards. The civil structures in the reference design, Flamanville 3 in
France, were designed using the EPR™ Technical Code for Civil Works (ETC-C) Rev B 2006.
The current version of this code, AFCEN ETC-C 2010 Edition will be used for the UK EPR™ with
an accompanying UK Companion Document (UK CD) which has been specifically written to
specify any changes to the ETC-C that are required for the UK EPR™.
The Step 4 GDA assessment of both versions of the ETC-C and the UK Companion Document
found that there was not sufficient guidance given to designers and some of the technical clauses
within them had not been fully justified. Furthermore the UK CD did not adapt the ETC-C
sufficiently for use in the UK, for instance many French standards were quoted rather than using
UK or international standards that are regarded as current good practice. Technical documents
submitted to justify the UK CD either had outstanding queries that could not be resolved during the
GDA Step 4 process or the documents were received too late in the process to be adequately
assessed. Therefore GDA Issue GI-UKEPR-CE-02 Revision 1 was raised to allow the Regulator
to complete assessment of these documents.
The GDA issues had four actions as follows:
Action 1 Support the ONR assessment of supporting documents which justify the technical
basis for specific clauses in the AFCEN ETC-C 2010 and the UK CD.
Actions 2, 3 and 4 Revise the UK CD to address the regulatory observations on AFCEN ETC-C
2010 Part 0 (General), Part 1 (Design) and Part 2 (Construction) respectively.
EDF and AREVA produced a Resolution Plan to indentify the deliverables that would be submitted
in response to GI-UKEPR-CE-02 and its actions. This indentified that an updated UK CD would be
required in order for the technical clauses of the ETC-C to be adequately modified to comply with
UK standards and good practice. A suite of technical documents and methodologies was also
submitted and these provided the justification behind the technical clauses. Revisions would also
be required to the Pre-Construction Safety Case (PCSR) to resolve the issue.
The technical supporting documents submitted under Action 1 have now provided the additional
justification required, although further iterations were required in some cases. Certain technical
clauses within the UK CD needed to be modified to accurately specify the general, design or
construction requirements which results from the supporting documents. Design values and
factors which are dependent on site specific parameters must be confirmed by the licensee during
detailed design, and so I have raised Assessment Findings AF-UKEPR-CE-76 to 78.
Action 1 also required justification of three specific design methodologies: detailing provisions, pool
liner design and drop load analysis. These are summarised below.
The detailing provisions for Class 1 safety structures of the UK EPR™ are based on a fully elastic
response with some additional measures based on EDF and AREVA’s feedback experience from
operating sites and current good practice to avoid cliff edge effects. I have therefore raised
Assessment Finding AF-UKEPR-CE-79 to require the licensee to confirm that there is adequate
margin beyond design basis for non-massive structural elements such that if plasticity occurs in
any part of those elements for the event considered, this will not lead to sudden failure. I also raise
Assessment Finding AF-UKEPR-CE-80 which requires the licensee to provide the final
construction specification and details for the joints within the concrete dome roof to the inner
containment, and justify that the finished structure will fulfil the nuclear safety requirements.

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The methodology for the design of pool liners has been provided and it was found to be
satisfactory. The liner strain limits specified in the AFCEN ETC-C 2010 have been revised to
agree with the ASME Section III, Division 2 code for Concrete Containments which is acceptable.
The methodology for analysing the impact of dropped loads onto civil structures has been
provided. The AFCEN ETC-C 2010 also specifies the method to calculate impacts on civil
structures from internal missiles. This method is included in the dropped load methodology
document. I am satisfied that this document provides adequate methods, however, some are only
applicable in certain circumstances and so I have raised Assessment Findings AF-UKEPR-CE-81
and AF-UKEPR-CE-82 to require the licensee to confirm the correct method is used for the correct
dropped load scenario. I also raise AF-UKEPR-CE-83 to require the licensee to provide the site
specific internal missile methodology document and justify the calculation methods used to assess
the damage to civil structures due to impact from potential internal missiles. The document shall
also confirm that this methodology is consistent with the dropped load methodology.
The deliverable submitted in response to Actions 2, 3 and 4 was an updated UK CD. The final
submission, Rev E, comprises amendments of certain technical clauses which address the
comments raised by the Regulator in the context of GDA.
The ONR assessment of the information provided in response to GI-UKEPR-CE-02 concludes that
the latest revision of the UK CD (Revision E) provides adequate guidance to designers and that the
technical clauses queried are in accordance with the standards expected by the UK Regulator.
ONR considers that the ETC-C as modified by the UK CD is now suitable for use as the design
code for the nuclear safety related structures of the UK EPR™. It also provides additional criteria
for the construction of these structures, for instance special requirements for the pre-stressed
containment building, which have benefitted from operational knowledge at existing EPR sites. It
should be noted, however, that the ETC-C is not a full construction specification for civil works; as
these will only be produced during the detailed design phase
I have therefore found EDF and AREVA’s response to GI-UKEPR-CE-02 to be satisfactory and
recommend this issue is closed.

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LIST OF ABBREVIATIONS

ABSC ABS Consulting Ltd

ACI American Concrete Institute
AF Assessment Finding
AFCEN Association Française pour les règles de conception et de construction
des matériels des Chaudières Électro Nucléaires
(French society for design, construction and in-service inspection rules
for nuclear island components)
ALARP As low as is reasonably practicable
AREVA AREVA NP SAS
Arup Ove Arup and Partners Ltd
ASCE American Society of Civil Engineers
ASME American Society of Mechanical Engineers
C1 Class 1 civil structures
CEA Commissariat à l'énergie atomique et aux énergies alternatives
(French Alternative Energies and Atomic Energy Commission)
CEB Comite Euro-International du Beton
CEEH Civil Engineering and External Hazards
CIRIA Construction Industry Research and Information Association
CMF Change Modification Form
CTICM Centre Technique Industriel de la Construction Metallique i.e. The
French equivalent of the UK Steel Construction Institute
CW Civil works
DAC Design Acceptance Confirmation
DCH Ductility Class High (to Eurocode 8)

DCM Ductility Class Medium (to Eurocode 8)

EDF Electricité de France SA

ETC-C EPR Technical Code for Civil Works

FA3 Flamanville 3 EPR Nuclear Power Plant, France
FE Finite element
FIB Federation Internationale du Beton
FRS Floor response spectra
GDA Generic Design Assessment
HSE Health and Safety Executive
HOW2 ONR’s Business Management System
IC Inner Containment

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LIST OF ABBREVIATIONS

IAEA International Atomic Energy Agency

MAEVA MAquette Enceinte en Vapeur et en Air (Steam and Air Containment
Model) – French test facility
NI Nuclear island
ONR Office for Nuclear Regulation (an agency of HSE)
PCSR Pre-construction Safety Report
SA Soft soil type
SAP Safety Assessment Principle(s) (HSE)
SI Site Investigation
TAG Technical Assessment Guide(s) (ONR)
TQ Technical Query
TSC Technical Support Contractor (for ONR)
UK CD UK Companion Document to AFCEN ETC-C
WENRA Western European Nuclear Regulators’ Association

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TABLE OF CONTENTS
1 INTRODUCTION ...................................................................................................................... 1
1.1 BACKGROUND .............................................................................................................. 1
1.2 SCOPE ........................................................................................................................... 2
1.3 METHODOLOGY............................................................................................................ 2
1.4 STRUCTURE OF THIS REPORT................................................................................... 2
2 ONR’S ASSESSMENT STRATEGY FOR GDA CLOSE-OUT ................................................. 3
2.1 CLOSE-OUT PLAN......................................................................................................... 3
2.2 THE APPROACH TO ASSESSMENT FOR GDA ISSUE CLOSE-OUT ......................... 3
2.3 STANDARDS AND CRITERIA ....................................................................................... 3
2.3.1 Safety Assessment Principles 4
2.3.2 Technical Assessment Guides 4
2.3.3 National and International Standards and Guidance 4
2.4 USE OF TECHNICAL SUPPORT CONTRACTORS ...................................................... 5
2.5 OUT-OF-SCOPE ITEMS ................................................................................................ 5
3 GDA ISSUE .............................................................................................................................. 6
3.1 BACKGROUND TO THE ETC-C .................................................................................... 6
3.2 GDA STEP 4 REVIEW.................................................................................................... 7
3.3 GDA ISSUE ACTIONS ................................................................................................... 7
3.4 EDF AND AREVA RESOLUTION PLAN DELIVERABLES ............................................ 8
3.5 INTERFACE WITH THE PCSR .................................................................................... 11
3.6 INTERFACE WITH OTHER GDA ISSUES ................................................................... 11
4 ONR ASSESSMENT .............................................................................................................. 12
4.1 SCOPE OF ASSESSMENT UNDERTAKEN ................................................................ 12
4.2 PROGRESS OF THE ASSESSMENT .......................................................................... 12
4.3 ASSESSMENT OF RESPONSE TO ACTION 1 ........................................................... 13
4.3.1 Introduction 13
4.3.2 Revised Supporting Technical Documents 13
4.4 DETAILING PROVISIONS............................................................................................ 23
4.4.1 Introduction 23
4.4.2 Detailing Rules for Reinforced Concrete and Steel Structures ENGSGC110157 23
4.4.3 Construction Joint Design Method - ENGSGC110222 Rev A 25
4.4.4 Bent Down Bars 27
4.5 POOL LINER DESIGN.................................................................................................. 28
4.5.1 Introduction 28
4.5.2 Methodology for Pool Liner Design - ENGSGC110243 28
4.5.3 Liner Performance subject to Concrete Cracking - ENGS110046 29
4.6 DROP LOAD ANALYSIS .............................................................................................. 32
4.6.1 Introduction 32
4.6.2 Dropped Load Methodology – ENGSGC100483 32
4.6.3 Impacts on Civil Structures from Internal Missiles - ECEIG091634 Rev B1 36

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4.7 ASSESSMENT OF RESPONSE TO ACTION 2 ........................................................... 39

4.7.1 Introduction 39
4.7.2 Assessment 39
4.7.3 Conclusions for Action 2 40
4.8 ASSESSMENT OF RESPONSE TO ACTION 3 ........................................................... 41
4.8.1 Introduction 41
4.8.2 Assessment 41
4.8.3 Conclusions for Action 3 43
4.9 ASSESSMENT OF RESPONSE TO ACTION 4 ........................................................... 44
4.9.1 Introduction 44
4.9.2 Assessment 44
4.9.3 Conclusions for Action 4 44
5 INTERFACE OF GI-UKEPR-CE-02 WITH KEY DOCUMENTS............................................. 46
5.1 REVIEW OF THE PCSR............................................................................................... 46
5.2 INTERFACE WITH OTHER GDA ISSUES ................................................................... 47
6 ASSESSMENT FINDINGS .................................................................................................... 48
6.1 ADDITIONAL ASSESSMENT FINDINGS..................................................................... 48
6.2 IMPACTED STEP 4 ASSESSMENT FINDINGS .......................................................... 49
7 ASSESSMENT CONCLUSIONS ........................................................................................... 50
8 REFERENCES ....................................................................................................................... 51

Tables
Table 1: Relevant SAPs Considered for Close-out of GI-UKEPR-CE-02 ....................................... 59
Table 2: Resolution Plan Deliverables for GI-UKEPR-CE-02……………..…………………………… 9
Table 3: Interface of GI-UKEPR-CE-02 with other GDA Issues…..……………………………...…....11

Annexes
Annex 1: GDA Assessment Findings Arising from GDA Close-out for GI-UKEPR- …………..61
CE-02 Rev 1

Annex 2: GDA Issue, Use of ETC-C for the Design and Construction of the UK …………..63
EPR™, GI-UKEPR-CE-02 Rev 1

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1 INTRODUCTION

1.1 BACKGROUND
1 This report presents the close-out of the Office for Nuclear Regulation’s (an agency of the
HSE) Generic Design Assessment (GDA) within the area of Civil Engineering and
External Hazards. The report specifically addresses the GDA Issue GI-UKEPR-CE-02
Rev 1 and its associated four actions (Ref. 1) generated as a result of the GDA Step 4
Civil Engineering and External Hazards Assessment of the UK EPR™ (Ref. 2). The
assessment has focused on the deliverables identified within the EDF and AREVA
Resolution Plan (Ref. 3) published in response to the GDA Issue and on further
assessment undertaken of those deliverables.
2 GDA followed a step-wise-approach in a claims-argument-evidence hierarchy. In Step 2
the claims made by EDF and AREVA were examined and in Step 3 the arguments that
underpin those claims were examined. The Step 4 assessment reviewed the safety
aspects of the UK EPR™ reactor in greater detail, by examining the evidence, supporting
the claims and arguments made in the safety documentation.
3 The Step 4 Civil Engineering and External Hazards (CEEH) Assessment identified six
GDA Issues and 68 Assessment Findings as part of the assessment of the evidence
associated with the UK EPR™ reactor design. GDA Issues are unresolved issues
considered by regulators to be significant, but resolvable, and which require resolution
before nuclear island safety related construction of such a reactor could be considered.
Assessment findings are findings that are identified during the regulators’ GDA
assessment that are important to safety, but not considered critical to the decision to start
nuclear island safety related construction of such a reactor.
4 The Step 4 Assessment concluded that the UK EPR™ reactor was suitable for
construction in the UK subject to resolution of the 31 GDA Issues resulting from all
assessment technical topics. The purpose of this report is to provide the assessment
which underpins the judgement made in closing GDA Issue GI-UKEPR-CE-02 arising
from the CEEH assessment.
5 The EPR™ Technical Code for Civils works (ETC-C) was developed by EDF and AREVA
for the design of the new fleet of EPR™ nuclear power plants. The current version of this
code, AFCEN ETC-C 2010 (Ref. 4), has a UK Companion Document (UKCD, Ref. 5) to
be used alongside it which specifies any changes to the technical clauses required for
application in the UK. In addition, there is a range of supporting references to the UK CD
which provide detailed supplementary guidance. During its assessment, ONR raised a
series of technical comments, the responses to which were received towards the end of
the Step 4 process and so were not reviewed in detail at that time. Therefore, GI-
UKEPR-CE-02 was raised to allow ONR to complete its assessment.
6 The EDF and AREVA safety case for the UK EPR™ design is contained within the Pre-
construction Safety Report (PCSR) with the technical detail presented in the supporting
documentation. The PCSR was originally submitted for GDA assessment in June 2008.
EDF and AREVA revised and resubmitted the consolidated PCSR in March 2011 (Ref. 6)
in response to the findings of the ONR assessment and this forms the safety case for
GDA Step 4. Sub-chapters 3.3 and 3.8 of the March 2011 PCSR describe the design of
safety classified civil structures and the codes and standards used in the EPR™ design
respectively. EDF and AREVA has proposed in its resolution plan that these may require
further revision following the resolution of GI-UKEPR-CE-02.

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1.2 SCOPE
7 This report presents only the assessment undertaken as part of the resolution of this
GDA Issue. This report should be read in conjunction with the Step 4 CEEH Assessment
Report (Ref. 2) and the close-out reports for the other CEEH GDA Issues (Ref. 7 to 10) in
order to appreciate the totality of the assessment of the evidence undertaken as part of
the GDA process.
8 This assessment report is not intended to revisit aspects of assessment already
undertaken and confirmed as being adequate during previous stages of the GDA.
However, should evidence from the assessment of EDF and AREVA’s responses to GDA
Issues highlight shortfalls not previously identified during Step 4, there will be a need for
these aspects of the assessment to be highlighted and addressed as part of the close-out
phase or be identified as assessment findings to be taken forward to site specific phase.
9 The possibility of further assessment findings being generated as a result of this
assessment is not precluded given that resolution of the GDA Issues may leave aspects
of the assessment requiring further detailed evidence when the information becomes
available at a later stage.

1.3 METHODOLOGY
10 The methodology applied to this assessment is identical to the approach taken during
Step 4 which followed the ONR business management system HOW2 document PI/FWD
“Permissioning - Purpose and Scope of Permissioning”, Issue 3 (Ref. 11), in relation to
mechanics of assessment within ONR.
11 This assessment has been focused primarily on the submissions relating to resolution of
the GDA Issue as well as any further requests for information or justification derived from
assessment of those specific deliverables.
12 The assessment allows ONR to judge whether the submissions provided in response to
the GDA Issue are sufficient to allow it to be closed. Where requirements for more
detailed evidence have been identified that are appropriate to be provided at the design,
construction or commissioning phases of the project these can be carried forward as
assessment findings.
13 The scope of this assessment is not to undertake further assessment of the PCSR nor is
it intended to extend this assessment beyond the expectations stated within the GDA
Issue Actions, however, should information be identified that has an affect on the claims
made for other aspects of civil engineering structures such that the existing case is
undermined, these have been addressed.

1.4 STRUCTURE OF THIS REPORT

14 This assessment report structure differs slightly from the structure adopted for the
previous reports produced within GDA, most notably the Step 4 CEEH assessment (Ref.
2). This report has been structured to reflect the assessment of the individual GDA Issue
rather than a report detailing close-out of all GDA Issues associated with this technical
area.
15 The reasoning behind adopting this report structure is to allow closure of GDA Issues as
the work is completed rather than having to wait for the completion of all the GDA work in
this technical area.

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2 ONR’S ASSESSMENT STRATEGY FOR GDA CLOSE-OUT

2.1 CLOSE-OUT PLAN

16 The intended assessment strategy for GDA Close-out for the Civil Engineering and
External Hazards topic area was set out in an assessment plan (Ref. 12) that identified
the intended scope of the assessment and the standards and criteria that would be
applied.
17 The assessment plan was based on:
 the EDF and AREVA resolutions plans for all six Civil Engineering GDA Issues;
 the project programmes contained in the resolution plans;
 the work scope for technical support contractors (TSC) commissioned by ONR to
support the assessment; and
 internal ONR resources and interaction with other topic Inspectors.
18 The scope of work contained within the assessment plan comprised assessment of the
following:
 technical submissions made to ONR in accordance with the resolution plans;
 whether an update was required to the March 2011 Pre-construction Safety Report
(PCSR) (Ref. 6) which had been reviewed during the GDA; and
 updates to the various documents supporting the PCSR.

2.2 THE APPROACH TO ASSESSMENT FOR GDA ISSUE CLOSE-OUT

19 The approach to the closure of GDA Issues for the UK EPR™ Project has involved the
assessment of the submissions made by EDF and AREVA in response to the GDA Issue
identified through the GDA process. These submissions are detailed within the EDF and
AREVA Resolution Plan for the GDA Issue.
20 The majority of deliverables for close-out had been submitted towards the end of Step 4
in response to the queries raised by ONR, but these had not been assessed in detail at
that time to confirm if the queries had been addressed. EDF and AREVA adopted the
use of a single document to track each of the individual ONR comments by using the
ETC-C Tracking Spreadsheet, document ENGSGC110269 (Ref. 13). This allowed a
staged response to be made, recorded by this tracking sheet, and comprising updated
UK CD clauses in an accompanying modification file, Appendix 1 to ENGSGC110269
(Ref. 14). ONR then provided comments in response to the staged changes. This
process was iterated until convergence was reached on the relevant technical point.
Both documents were agreed as closed in September 2012 and are ENGSGC110269
Rev E (Ref. 13) and Appendix 1 to ENGSGC110269 Rev E (Ref. 14).
21 During the GDA close-out phase, regular Level 4 technical meetings and workshops have
been held to allow discussion and clarification with EDF and AREVA on its submission
documents. New or updated documents were submitted in order to justify the technical
basis for the revised UK CD clauses. Documents submitted therefore may have been
revised two or three times until they met regulatory expectations.

2.3 STANDARDS AND CRITERIA

22 The relevant standards and criteria adopted within this assessment are principally the
Safety Assessment Principles (SAP), internal ONR Technical Assessment Guides (TAG),
relevant national and international standards and relevant good practice informed from

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existing practices adopted on UK nuclear licensed sites. The key SAPs and relevant
TAGs have been detailed within this section. National and international standards and
guidance have been referenced where appropriate within the assessment report.
Relevant good practice, where applicable, has also been cited within the body of the
assessment.

2.3.1 Safety Assessment Principles

23 The key SAPs applied within the assessment of GDA Issue GI-UKEPR-CE-02 are
included within Table 1 of this report. These are taken from Safety Assessment
Principles for Nuclear Facilities. 2006 Edition Rev 1 (Ref. 15).

2.3.2 Technical Assessment Guides

24 The following Technical Assessment Guides have been used as the major underpinning
guides for this assessment (Ref. 16):
 T/AST/013 External Hazards
 T/AST/017 Structural Integrity: civil engineering aspects
25 Other TAGs have been consulted as appropriate. These include:
 T/AST/005 ONR guidance on the demonstration of ALARP (as low as
reasonably practicable)
 T/AST/004 Fundamental Principles

2.3.3 National and International Standards and Guidance

26 The following international standards and guidance have been used as part of this
assessment:
 International Atomic Energy Agency (IAEA) Safety Standard Series (Ref. 17)
 Western European Nuclear Regulators’ Association (WENRA) Reactor Reference
Safety Levels (Ref. 18)
 BS EN 1990, Eurocode 0, Basis of Structural Design (Ref. 19)
 BS EN 1991, Eurocode 1, Actions on Structures (Ref. 20)
 BS EN 1992, Eurocode 2, Design of Concrete Structures (Ref. 21) and its UK
National Annex.
 BS EN 1993, Eurocode 3, Design of Steel Structures (Ref. 22) and its UK National
Annex.
 BS EN 1998, Eurocode 8, Design of Structures for Earthquake Resistance (Ref. 23)
and its UK National Annex.
 ACI 349-06, Code Requirements for Nuclear Safety-Related Concrete Structures
and Commentary, American Concrete Institute. 2006 (Ref. 24).
 ACI 318-11, Building Code Requirements for Structural Concrete and Commentary,
American Concrete Institute, 2011 (Ref. 25)
 ASME Boiler and Pressure Vessel Code. Code for Concrete Containments – Rules
for Construction of Nuclear Facility Components . ACI 359M-07 Section III, Division
2 (Ref. 26)

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 Fastenings to Concrete and Masonry Structures, CEB Bulletin No 216, 1994 (Ref.
27)
 Early-age thermal crack control in concrete, CIRIA Guide C660, 2007 (Ref. 28).

2.4 USE OF TECHNICAL SUPPORT CONTRACTORS

27 Technical support to ONR on the assessment of the AFCEN ETC-C 2010 and its
accompanying UK CD to confirm the design and construction requirements for the UK
EPR™ has been provided by Ove Arup and Partners Ltd (Arup).
28 The ONR assessment of the dropped load methodology was supported by ABS
Consulting Ltd (ABSC) who carried out a technical review against the SAPs and against
current good practice in the UK nuclear industry.

2.5 OUT-OF-SCOPE ITEMS

29 There are no out of scope items. The entirety of GDA Issue GI-UKEPR-CE-02 Rev 1 has
been addressed. In addition, there are no changes to the scope of the GDA assessment
detailed in the Step 4 report (Ref. 2).

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3 GDA ISSUE

3.1 BACKGROUND TO THE ETC-C

30 The “EPR Technical Code for Civil Works” (ETC-C) for nuclear safety related structures
was the subject of extensive discussions between ONR and EDF and AREVA during
Step 4 of GDA. The civil structures in the reference design, Flamanville 3 in France,
were designed using the ETC-C Rev B 2006 (Ref. 30). The current version of this code,
AFCEN ETC-C 2010 (Ref. 4), will be used for the UK EPR™, with an accompanying UK
Companion Document (Ref. 5) which has been specifically written to specify any changes
to the ETC-C that are required for the UK EPR™. This is an important document, as its
use will be mandatory and will govern over the ETC-C in a similar way that the UK
National Annexes govern Eurocodes.
31 The ETC-C is a bespoke code, developed by EDF and AREVA for the design of the new
fleet of EPR™ nuclear power plants, including Flamanville 3 (FA3). The ETC-C is
intended for Class 1 safety classified structures only and is based upon Eurocodes,
European Standards, French standards and other recognised guidance, but specifies
additional criteria to be used for the EPR™. This reflects that some Eurocode rules
should be amended and / or extended to apply to the specific demands placed on nuclear
structures. These additional criteria have been developed within the French nuclear
industry over the past decades.
32 The ETC-C has now come under the auspices of AFCEN (French society for design,
construction and in-service inspection rules for nuclear island components). AFCEN is a
body set up in France to develop design and construction codes for nuclear power
stations in light of current good practice and developments in research and development
(R&D). It was founded by the French Alternative Energies and Atomic Energy
Commission (CEA) and experts from the French nuclear industry. Therefore, the AFCEN
2010 version of the ETC-C is a stand alone document, and EDF and AREVA use the UK
Companion Document to adapt it for the UK EPR™.
33 The contents of the ETC-C are as follows.
 Part 0: General. This defines the structure and the scope of the ETC-C.
 Part 1: Design. This defines the rules or criteria needed to design the C1-classified
structures. This includes the actions and combinations of actions to be taken into
account in the design of civil works. However, numerical values (intensity of loads)
associated to these actions are provided by specific documents for each EPR™
Project.
 Part 2: Construction. This provides construction rules (concrete, reinforcement,
prestressing system, leaktightness of metal parts, etc).
 Part 3: Leak and Resistance Test and Containment Monitoring. This provides the
main principles for containment testing, covering the initial acceptance test and
subsequent periodic tests.
34 The UK CD contains amended clauses to all the above parts of the ETC-C and also
corrects errata in the AFCEN 2010 version. These are listed in Appendices 1 and 2 of
the UK CD (Ref. 5).

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3.2 GDA STEP 4 REVIEW

35 This section provides a brief overview of the GDA assessment of the ETC-C and its
supporting documents and the outcomes of that assessment which resulted in GDA Issue
GI-UKEPR-CE-02.
36 The GDA Step 4 review comprised assessment firstly of the ETC-C Rev B 2006 (Ref. 30)
and then of the AFCEN ETC-C 2010 (Ref. 4) which was received in December 2010,
towards the end of Step 4.
37 During the ONR review of ETC-C Rev B, a number of Technical Queries (TQs) were
raised requesting clarification of many aspects of the ETC-C. In order to supplement the
ETC-C and especially to collate the clarifications of the many issues raised in the course
of the review, EDF developed an ETC-C User Guide which was later to become the UK
Companion Document (UK CD).
38 Section 4.3.3 of the ONR Step 4 assessment report (Ref. 2) describes the assessment of
the ETC-C and the UK CD. It notes that while the ETC-C Rev B was included in the
assessment process, it is the later AFCEN ETC-C which is the GDA design code, along
with its UK CD. The first issue of the UK CD, Rev A (Ref. 31) was submitted in February
2011 and was assessed as part of Step 4.
39 The Step 4 review of the AFCEN ETC-C 2010, the UK CD Rev A and the supporting
reference documents (refer to Table 2) identified a number of areas where further
justification was required. These are outlined in Section 4.3.3.6.2 of the Step 4
assessment report (Ref. 2). The detailed comments from ONR were issued to EDF and
AREVA in early 2011 via Letters EPR70291R (Ref. 32), EPR70304R (Ref. 33) and
EPR70367R (Ref. 34). The comments in these letters were complied into the ETC-C
tracking spreadsheet (Ref. 13) described in Section 2.2.

3.3 GDA ISSUE ACTIONS

40 There are four actions attached to GI-UKEPR-CE-02 Rev 1 as follows.
41 Action 1 - Support assessment within the following areas by providing adequate
responses to any questions arising from assessment by ONR of documents submitted
during GDA Step 4 but not reviewed in detail at that time:
1)  cc coefficient for concrete compressive strength
2) Load Combination Factors ψi for variable actions
3) Biaxial Stress Limits
4) Shear
5) Fastenings – partial safety factors
6) Pre-stressing Participation
7) Shrinkage
8) Crack width control
9) Pre-stressing partial safety factor,

42 Provide additional supporting documents on the following areas

 Detailing provisions
 Pool Liner Design
 Drop Load Analysis

43 Action 2 - Provide a revision of the UK companion document which addresses the

observations raised on ETC-C Part 0: General, as a result of the Step 4 assessment.

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44 Action 3 - Provide a revision of the UK companion document which addresses the

observations raised on ETC-C Part 1: Design, as a result of the Step 4 assessment.
45 Action 4 - Provide a revision of the UK companion document which addresses the
observations raised on ETC-C Part 2: Construction, as a result of the Step 4 assessment.

3.4 EDF AND AREVA RESOLUTION PLAN DELIVERABLES

46 The information provided by EDF and AREVA in response to this GDA Issue, as detailed
within its Resolution Plan (Ref. 3), was broken down into the four GDA Issue Actions and
then further broken down into specific deliverables for detailed assessment. The
documents listed in Table 2 are mainly updates to documents already received and
assessed during Step 4, as shown. However, new deliverables were also identified as
being required. Those marked * were identified as planned in the Resolution Plan, but an
actual document number was not given; this became available later when the documents
were submitted but is given for clarity. These versions of the documents underwent
several revisions during my assessment until regulatory expectations were satisfied (as
described in later sections of this report as noted in Table 2).
47 It is important to note that the information shown in Table 2 is supplementary to the
information provided within the March 2011 PCSR (Ref. 6) which has already been
subject to assessment during earlier stages of GDA. In addition, it is important to note
that the deliverables are not intended to provide the complete safety case for the Civil
Engineering and External Hazards topic area. Rather they form further detailed
arguments and evidence to supplement those already provided during earlier Steps
within the GDA Process.

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Table 2: Resolution Plan Deliverables for GI-UKEPR-CE-02

Revision Resolution Final Discussed in

Document Number Document Title Assessed in Plan GI Close-Out Section # of this
Step 4 Deliverable Submission Report
ACTION 1 - NINE TECHNICAL AREAS FROM STEP 4
1) ENGSGC100384 Determination of the α cc coefficient used in the formula for the A B B Section 4.3.2.1
design value of the compressive strength in Eurocode 2. (Ref. 35)
2) ENGSGC100394 Presentation and justification of ψi factors of ETC-C for variable A B C Section 4.3.2.2
actions in accidental and non-accidental situations (Ref. 36) (Ref. 53)
3) ENGSGC100415 Justification of the Concrete Maximum Compressive Stress Under A B B Section 4.3.2.3
Bi-axial / Tri-axial Behaviour (Ref. 37)
4) ENGSGC100410 EPR™ UK – Shear Design Proposal A C D Section 4.3.2.4
(Ref. 38) (Ref. 54)
5) ENGSGC100395 Steel and Concrete Partial Safety Factors for EPR™ Fastening A B B Section 4.3.2.5
Systems (Ref. 39)
6) ENGSGC100416 Prestressing Tendons Participation in Reinforced Concrete A B C Section 4.3.2.6
Calculations for the Inner Containment (Ref. 40) (Ref. 55)
7) ENGSGC100426 Methodology for Consideration of Shrinkage for EPR™ Concrete A B B Section 4.3.2.7
Structures (Ref. 41)
8) ENGSGC100428 Verification of Crack Width for EPR™ - Concrete Structures A B B Section 4.3.2.7
(Ref. 42)
7) & 8) Global approach about methodology for consideration of shrinkage n/a A A Section 4.3.2.7
ENGSGC110025 and crack limitation (Ref. 43)
9) ENGSGC100402 Justification of the Partial Factor for Prestressing Actions γ P A n/a A Section 4.3.2.8
(Ref. 44)

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Table 2: Resolution Plan Deliverables for GI-UKEPR-CE-02

Revision Resolution Final Discussed in

Document Number Document Title Assessed in Plan GI Close-Out Section # of this
Step 4 Deliverable Submission Report
ADDITIONAL SUPPORTING DOCUMENTS

ENGSGC110157* Good Practice Detailing Rules for Reinforced Concrete and Steel n/a A B Section 4.4
Structures. (Ref. 45) (Ref. 56)
ENGSGC110243* Methodology Report for Pool Liners n/a A B Section 4.5
(Ref. 46) (Ref. 57)
ENGSGC100483 Methods with regard to the risk of dropped loads n/a A B Section 4.6
(Ref. 47) (Ref. 58)
ACTIONS 2, 3 AND 4

ENGSGC110015 UK Companion Document to AFCEN ETC-C A B E

(Ref. 31) (Ref. 48) (Ref. 5)
ENGSGC110033 Assessment File of the UK Companion Document to AFCEN ETC-C n/a B C
(Ref. 49) (Ref. 59)
ECEIG 111110* EPR Nuclear Island Civil Engineering Design Process Note (see n/a A C Section 4.7
GDA Issue GI-UKEPR-CE01) (Ref. 50) (Ref. 60) Section 4.8
and Section 4.9
ETDOIG110305 ETC-C Part 2.10 – Mapping of Changes from ETC-C Rev B to n/a A A
AFCEN ETC-C 2010 (Ref. 51)
EDTGC110381 ETC-C Part 2: Construction Update – Mapping of Changes from n/a A A
ETC-C Rev B to AFCEN 2010 ETC-C (Sections 2.2 to 2.5, 2.11, (Ref. 52)
and 2.12)

* document which was listed in the Resolution Plan but no document number assigned

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3.5 INTERFACE WITH THE PCSR

48 The Resolution Plan for GI-UKEPR-CE-02 (Ref. 3) states that updates to the March 2011
PCSR will be required on the following sub-chapters.
 “Sub-chapter 3.3 – Design of safety Classified Civil Structure”.
 “Sub-chapter 3.8 – Codes and Standards used in the EPR™ design”.

3.6 INTERFACE WITH OTHER GDA ISSUES

49 This GDA Issue has interfaces with deliverables for other GDA Issue resolution plans, as
given in Table 3 below. This means that some of the commitments made by EDF and
AREVA in order to resolve this GDA Issue are included in documents produced as
deliverables for other GDA Issues. Where this is the case, details of the commitment are
given in the appropriate section of this report.

Table 3: Interface of GI-UKEPR-CE-02 with other GDA Issues

GDA Issue Topic Document Deliverables

GI-UKEPR-CE-01 (Ref. 64) Hypothesis and EPR Nuclear Island Civil

Methodology Notes Engineering Design Process Note
Rev C (Ref. 60)
GI-UKEPR-CE-03 (Ref. 65) Beyond design basis N/A
behaviour of containment
GI-UKEPR-CE-04 (Ref. 66) Containment analysis FE UK Companion Document to the
modelling ETC-C
(Ref. 5)
GI-UKEPR-CE-05 (Ref. 67) Reliability of the ETC-C N/A
GI-UKEPR-CE-06 (Ref. 68) Seismic Analysis ENGSDS100268 Rev B Seismic
Methodology Analysis of Foundation Raft (Ref. 62)
ENGSDS100269 Rev B
Methodology for Seismic Analysis of
NI Buildings, (Ref. 63)
GI-UKEPR-IH-01 (Ref. 69) Dropped Loads Methods with regard to the risk of
dropped loads for EPR™ UK for civil
works structures, ENGSGC100483
Rev B (Ref. 58)
GI-UKEPR-IH-04 (Ref. 70) Internal Missiles Methods with regard to the risk of
dropped loads for EPR™ UK for civil
works structures, ENGSGC100483
Rev B (Ref. 58)
GI-UKEPR-CC-01 (Ref. 71) Classification of civil NEPS-F DC 557 Rev D
structures Classification of Structures Systems
and Components (Ref. 72)

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4 ONR ASSESSMENT

4.1 SCOPE OF ASSESSMENT UNDERTAKEN

50 The scope of the assessment has been to consider the expectations detailed down within
the GDA Issue, GI-UKEPR-CE-02 (Ref. 1), and its four actions. The issue is presented in
Annex 2 of this report.
51 Further to the assessment work undertaken during Step 4 (Ref. 2), this assessment
focuses on the “EPR™ Technical Code for Civil Structures” AFCEN ETC-C 2010 (Ref. 4)
and its application for the UK EPR™ which is specified by the UK Companion Document
(UK CD) (Ref. 5). Identified deliverables intended to provide the requisite evidence were
provided within the responses contained within the Resolution Plan (Ref. 3) provided by
EDF and AREVA at the end of Step 4 of GDA.
52 This assessment has been carried out in accordance with the ONR business
management system HOW2 document PI/FWD “Permissioning - Purpose and Scope of
Permissioning”, Issue 3 (Ref. 11).
53 In summary, the purpose of the assessment was to judge whether the deliverables
submitted in response to GI-UKEPR-CE-02 provided sufficient justification of the AFCEN
ETC-C 2010 as amended by the UK CD for use as the design code for the UK EPR™
Class 1 civil structures.

4.2 PROGRESS OF THE ASSESSMENT

54 EDF and AREVA submitted individual technical documents to justify its approach for the
nine specific points under Action A1 (refer to paragraph 41). The Step 4 GDA review of
Parts 0, 1 and 2 of the ETC-C had remnant queries which were summarised in Actions
A2, A3 and A4, and detailed in three ONR letters (Ref. 32, 33 and 34).
55 A workshop was held with EDF and AREVA in July 2011 to discuss how the comments
were to be progressed. EDF and AREVA had compiled the comments into a single
tracking spreadsheet (Ref. 13), which contained five comments on Part 0, 75 comments
on Part 1 and 64 comments on Part 2. It proposed a staged response where individual
comments would be cleared by either providing justification for the approach used in the
ETC-C or how the UK CD amended that particular clause. A new document referred to
as a modification file (Ref. 14) would be used to record the revised UK CD clauses as
they were progressed.
56 The ONR assessment comprised review of the individual revised UK CD clauses and
was supported by Arup. This staged approach required much iteration and the tracking
sheet and the modification file were updated at each stage. This process was repeated
until a preliminary version of the complete UK CD Rev D was submitted in March 2012
(Ref. 73). I then commissioned Arup to carry out a consolidated review of the complete
document to check its coherency. This generated a final round of comments which were
resolved in Rev E of the UK CD (Ref. 5) submitted in September 2012.
57 EDF and AREVA also produced documents called assessment files to accompany the
various revisions of the UK CD submitted. The assessment file records the reasons
behind each changed clause and the supporting justification. It also records the
justification provided for clauses that were scrutinised by ONR, but then subsequently
proven to have sufficient justification. Three assessment files were produced for the UK
CD during GDA Issue close-out (Refs. 59, 75 and 76).

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4.3 ASSESSMENT OF RESPONSE TO ACTION 1

4.3.1 Introduction
58 Action 1 of GI-UKEPR-CE-02 comprised the assessment of updates to the supporting
documents for nine specific technical areas of the UK CD (Refs. 35 to 44 as shown in
Table 2). Action 1 also requested additional justification with respect to detailing
provisions, pool liners and dropped loads.
59 Earlier versions of the nine technical reports had been assessed during GDA Step 4 by
ONR, supported by Arup. Eight reports were found to fall short of regulatory expectations
in that insufficient technical justification was made for the approach adopted. The
“Justification of the Partial Factor for Prestressing Actions γ P ” (Ref. 44) submitted in Step
4 was satisfactory and so this document did not need to be revised, although it is
included in Table 2 for information only. The revised technical documents were reviewed
again during GDA Issue Close-out and this is presented in Section 4.3.2.
60 New documents were submitted for the three additional topics in GI-UKEPR-CE-02.A1.
These are:
 “EPR™ Safety Category 1 (C1) Structures – Good Practice Detailing Rules for
Reinforced Concrete and Steel Structures”. ENGSGC110157 Rev A (Ref. 45),
 “Pool Liner Design Requirements and Methodology” ENGSGC110243 Rev A (Ref.
46), and
 “Methods with regard to the risk of dropped loads for EPR™ UK for concrete
structures” ENGSGC100483 Rev A (Ref. 47).
61 The assessments of these three topics are presented in Sections 4.4 to 4.6 respectively.

4.3.2 Revised Supporting Technical Documents

62 This section comprises the assessment of the technical reports listed in GI-UKEPR-CE-
02.A1. I requested that Arup carry out a technical review of the new revisions of these
reports against the versions it had reviewed during Step 4 GDA. The results are
presented in Arup report 209364-10-01 (Ref. 77).
4.3.2.1 Concrete Strength Coefficient α cc - ENGSGC100384 Rev B
63 EDF and AREVA submitted the technical document “Determination of the α cc coefficient
used in the formula for the design value of the compressive strength in Eurocode 2“
ENGSGC100384 Rev B (Ref. 35) in part response to GI-UKEPR-CE-02.A1.
64 The design code Eurocode 2, BS EN 1992 (Ref. 21) is for the design of concrete
structures. Part 1-1 introduces a term, α cc , to modify the design strength of concrete.
This is specified in Clause 3.1.6 of Eurocode 2, Part 1-1 as follows:
 “The value of the design compressive strength is defined as f cd = α cc f ck / γ C (Eqn
3.15) Where γ C is the partial safety factor for concrete, see 2.4.2.4, and
 α cc is the coefficient taking account of long term effects on the compressive strength
and of unfavourable effects resulting from the way the load is applied.”
65 The term α cc has a recommended value of 1.0 in Part 1 (general) of Eurocode 2, and a
recommended value of 0.85 in Part 2 (bridges). The UK National Annex (Ref. 21) adopts
a value of 0.85, for bending and axial load, for both parts of Eurocode 2, whilst the ETC-C
takes a value of 1.0. This was questioned by ONR during GDA Step 4 and the
justification given at that time (ENGSGC100384 Rev A) stated that 0.85 is generally used

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but a value of 1.0 is proposed for certain accidental actions. However, the justification
given for this did not meet regulatory expectation.
66 EDF and AREVA submitted ENGSGC100384 Rev B (Ref. 35) in response to GI-UKEPR-
CE-02.A1 with a revised approach that α cc should be 1.0 for accidental loads less than 2
hours duration and for loads which are principally strain induced. This is because the
effects on concrete compressive strength, that α cc accounts for, will not develop under
such short term loading
67 I am satisfied that the design approach in the AFCEN ETC-C 2010 for α cc is robust and
addresses the ONR comments raised under GDA Step 4. The use of the higher
coefficient for very short term loading has been adequately justified by ENGSGC100384
Rev B (Ref. 35). The use of α cc as 0.85 for all other types and durations of loads is in
accordance with the UK National Annex to BS EN 1992-1.
4.3.2.2 Load Combination Factors ψ i - ENGSGC100394 Rev C
68 EDF and AREVA’s submission for this specific query from GI-UKEPR-CE-02.A1 is the
technical document “GDA – Presentation and justification of ψi factors of ETC-C for
variable actions in accidental and non-accidental situations“, ENGSGC100394 Rev C
(Ref. 53).
69 The Eurocode approach for variable loads uses different combination factors (ψ i ) for
different situations depending on the nature of the variable load and what other variable
loads are combined with it. These ψ i factors are defined in Eurocode 0 BS EN 1990
“Basis of Structural Design” (Ref. 19) as follows.
 ψ0 = factor for combination value of a variable action (basic value = 0.7)
 ψ1 = factor for frequent value of a variable action (basic value = 0.5)
 ψ2 = factor for quasi-permanent value of a variable action (basic value = 0.3)
70 In the general accidental load case, the combination factor to be used is a Nationally
Determined Parameter and with a choice of ψ 1 or ψ 2 and no recommended value is
given. The UK National Annex however recommends ψ 1 is used, whereas ψ 2 is used in
France; therefore the UK approach is more conservative.
71 The Step 4 review of ENGSGC100394 Rev A concluded that the AFCEN ETC-C 2010
(Ref. 4) presents a load combinations table that has the factors of safety and the
combination factors combined which was not consistent with the Eurocode approach and
so lacked transparency. The use of Eurocode 0 combination factors for the UK EPR™
also required further justification, including the use of the French ψ 2 . The document did
not cover non-accidental load cases and in particular the design of walls for non-
accidental ultimate limit state loads.
72 ENGSGC100394 was revised twice; Rev B (Ref. 36) was provided as an interim position,
and Rev C (Ref. 53) issued in August 2011 as a final position on this subject. I requested
Arup carry out a comparison of Rev C with the Step 4 submission, Rev A. Arup’s review
is presented in its report (Ref. 77).
73 ENGSGC100394 Rev C is a significant revision since Rev A and includes justification of
all ψ i factors used rather than just ψ 2 . The document now shows the factors of safety
and the combination factors separately. The ψ i factors in Table A1.1 of Eurocode 0 are
grouped into different categories (A to H) according to building type. EDF and AREVA
has adopted Category G for heavily trafficked areas as being the closest to the
operational variable loads for structures like the UK EPR™. It is further argued that
Category G is a conservative comparison, as the EPR™ only experiences significant

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variable imposed loads at the end of construction and during exceptional maintenance.
Justification is given that the factors applied in the AFCEN ETC-C 2010 are either equal
to, or more conservative than, would be derived using a strict interpretation of Eurocode
0. The use of ψ 2 (French approach) for the main variable load in the accidental non-
seismic case is justified on the basis that frequency of load in the EPR™ is much lower
than load Category G and so using ψ 1 (UK approach) is too onerous.
74 I am satisfied that Ref. 53 now provides the transparency required by GI-UKEPR-CE-
02.A1. The factors of safety and the combination factors are identified separately and so
this is consistent with the Eurocode approach. I also regard the use of ψ 2 , for Category G
loading, acceptable for low frequency loading which is more applicable for nuclear plants
than loading due to heavily trafficked areas.
75 ENGSGC100394 Rev C (Ref. 53) has provided a suitable response to the original
queries from GDA Step 4. It contains adequate justification for the ψ i factors adopted
and that they are based on the Eurocode approach, with additional consideration for
special structures such as nuclear power plants.
4.3.2.3 Biaxial/Triaxial Stress Limits - ENGSGC100415 Rev B
76 EDF and AREVA’s submission for this specific query from GI-UKEPR-CE-02.A1 is the
technical document “Justification of the concrete maximum compressive stress under bi
axial/triaxial behaviour (accidental thermal conditions for the inner containment)”
ENGSGC100415 Rev B (Ref. 37).
77 The compressive strength of concrete in one direction can be enhanced when there is
another compressive force in an orthogonal direction. This orthogonal force is known as
the confining force. This principle for concrete under biaxial or triaxial stress states is
specified in the major internationally recognised design codes for concrete structures,
including Eurocode 2, BS EN 1992-2 Design of Concrete Structures (Ref. 21).
78 The ETC-C specifies a rule in Clause 1.4.5.2.1 that
Under accidental situations (accidental thermal stresses only), the maximum
compressive strength may be taken as 1.2 f ck / C instead of f ck / C when the section
is subjected to biaxial compression (case of a variable thermal effect for instance).
A more accurate calculation may be made by using EN 1992-2, Appendix LL.
79 During Step 4, Rev A of ENGSGC100415 was submitted as justification for increasing the
compressive stress limit by 20% (i.e. to 1.2f ck /c) for concrete under bi-axial or tri-axial
stress states. The ONR Step 4 assessment concluded that the method presented was
valid, however the document did not specify the minimum stresses in the other two
directions to justify a maximum stress of 1.2f ck /c in the third direction. ONR concluded
that these limitations should be specified in the relevant ETC-C clause.
80 ONR also commented that the maximum concrete stresses calculated should be based
on the actual concrete properties for the inner containment. The issue is that for UK
aggregates, the thermal expansion coefficient for concrete could be higher than that
assumed in the design. Therefore, further justification was requested that the design
values were adequate.
81 ENGSGC100415 Rev B (Ref. 37) was submitted for GDA Close-out. I found the revised
document to be acceptable since it adequately detailed the limitations to the application
of enhanced strength, and provided justification for the approach adopted based on
Eurocode 2 data and on some full scale testing results. However, since the UK
Companion Document is the key design specification to the civil works designer, I wanted

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to check that the relevant technical clauses were also adequate. Arup supported me in
this check under the consolidated review of the UK CD Rev D (Ref. 85).
82 Clause 1.4.5.2.1 bis of the UK CD states that the characteristic compressive strength of
concrete (f ck ) can be increased by 20% provided the transverse compression in one
direction is at least 0.12f ck and there is no tension in the other transverse direction. This
is mathematically correct for a concrete with an f ck of 60MPa, which is the case for the
inner containment concrete. However, it is not universally correct for all strengths of
concrete because the equations in BS EN 1992-2 Annex LL, are based on the mean, and
not the characteristic, strengths (i.e. f cm rather than f ck ). I therefore queried what EDF
and AREVA’s design rules would be for other strengths of concrete.
83 EDF and AREVA confirmed in the “Assessment File of Revision E of UK Companion
Document to the AFCEN ETC-C 2010” ENGSGC120228 Rev A (Ref. 75) that for the UK
EPR™, the inner containment wall structure is the only structure subject to such high
compressive loads that the strength enhancement must be invoked. Furthermore, the
enhancement is only required in the areas where the lateral stress is in the order of
0.66f ck . Therefore, EDF and AREVA proposed to change the minimum confining stress
required to 0.36f ck as an additional margin and since Clause 1.4.5.2.1 is within Section
1.4.5 “Specific Design Criteria for the Containment with Steel Liner” it can only be applied
to the inner containment concrete.
84 I am satisfied with the final version of Clause 1.4.5.2.1 bis in the UK CD Rev E (Ref. 5)
and concur that a minimum confining stress of 0.36 f ck is a conservative requirement.
85 In respect to my comment about using the actual properties of the inner containment
concrete for calculations, EDF and AREVA have confirmed that no further justification
can be provided until site specific phase when the properties will be known. Therefore, I
have raised the following assessment finding.
AF-UKEPR-CE-76: The licensee shall confirm that the enhanced concrete
compressive strength used for the design of the inner containment structure
accounts for the final concrete mix design specified, and in particular the
thermal expansion coefficient for the type(s) of aggregates to be used
Required Timescale: Nuclear Island Safety-Related Concrete.
86 It should be noted that the existing Step 4 Assessment Finding AF-UKEPR-CE-68 also
applies to the concrete properties of the finished structure.
4.3.2.4 Shear Reinforcement - ENGSGC100410 Rev D
87 EDF and AREVA’s submission for this specific query from GI-UKEPR-CE-02.A1 is the
technical document “EPR™ UK – Shear design proposal” ENGSGC100410 Rev D (Ref.
54).
88 The ETC-C design of shear reinforcement is based on the Eurocode 2 Part 1-1 (Ref. 21)
approach and the French National Annex to Eurocode 2. However, since this approach
is different to that of the UK National Annex further justification was required. Rev A of
document ENGSGC100410 was submitted during Step 4 to set out the basis for a
proposed revision to the ETC-C for the calculation of shear resistance and shear
reinforcement requirements. The principal comments raised on Rev A of this document
are summarised as follows:
 The shear link design method had not been justified sufficiently and since it was less
conservative than that in the UK National Annex to Eurocode 2, was found to be
unacceptable.

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 Limitations on concrete strength used in shear design due to the properties of UK

aggregates were not considered.
 Minimum link requirements did not include the rules for spacing of links, just the
minimum area.
89 Rev B of the document was submitted at the end of Step 4 and was not reviewed at that
time. Rev C (Ref. 38) was submitted under the EDF and AREVA Resolution Plan and
this was the version initially assessed for GDA Close-out (Ref. 77). Rev C had been
substantially revised which had introduced editorial errors. Technically, it was still found
to be lacking in a number of areas. The main areas of concern were over the use of
spacing rules for shear reinforcement which were outside the requirements of the UK
National Annex to Eurocode 2 and UK standard practice.
90 There was also a lack of clarity over the treatment and definition of primary and
secondary slabs and the treatment of load redistribution. The document aligns secondary
slabs with “members of minor importance” as defined in Eurocode 2. ONR disagreed
with this definition since the Eurocode defines “members of minor importance (e.g. lintels
with span < 2 m) which do not contribute significantly to the overall resistance and
stability of the structure”. The document also allows redistribution of loads based only on
slab geometry. The load arrangement must also be considered; for example, a slab with
uniform load over most of its area has nowhere to redistribute to.
91 EDF and AREVA proposed an approach outlined in Letter EPR01031N (Ref. 87) in
December 2011 and this was discussed with EDF and AREVA at the Level 4 Civil
Engineering technical meeting in January 2012. The approach adopted is a considerable
improvement on that previously presented. The spacing of shear reinforcement is now
fully compliant with Eurocode 2 and the UK National Annex. In addition, the definition of
primary and secondary slabs is improved. However, ONR provided a small number of
comments to EDF and AREVA (Ref. 88) which mainly discussed improvements to the
guidance to be provided in the UK CD. EDF and AREVA submitted a further document
ENGSGC110375 Rev B “Out of Plane Shear Reinforcement” (Ref. 89). ONR commented
(Ref. 90) that the definitions of the secondary slab and redistribution criteria could still be
made clearer.
92 Rev D of document ENGSGC100410 (Ref. 54) was submitted in February 2012 and
incorporated the new proposal. This was further reviewed by Arup (Ref. 84). Overall, the
proposed method has been revised so as to give a design at least as conservative as that
using the recommended values from Eurocode 2. The spacing of minimum shear
reinforcement in accordance with the UK National Annex has also now been included.
This method is therefore now acceptable.
93 One remnant comment was that justification of shear strength needs to relate to UK
aggregates in accordance with the UK National Annex to Eurocode 2 Part 1-1 Subclause
3.2.3 (2)P. EDF and AREVA confirmed this could not be finalised until the actual type of
aggregate is chosen by the licensee. Therefore I have raised the following assessment
finding.
AF-UKEPR-CE-77: The licensee shall confirm that design shear strength
used for reinforced concrete structures accounts for the final type(s) of
aggregates used in the concrete mix design in accordance with the UK
National Annex to Eurocode 2 BS EN 1992-1-1.
Required Timescale: First Structural Concrete.

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94 There also still remained the question of whether all the requirements for shear
reinforcement design had been included in the UK Companion Document. This was
assessed under the comprehensive review of the complete UK CD. The detail of this
review is reported in Arup report 209364-10-10 (Ref. 85). The main clause, 1.4.4.2.2 bis
states that Eurocode 2 requirements are replaced by Appendix 1.H bis. Although, 1.H bis
correctly states the UK CD approach is in addition to the Eurocode 2 checks, it could be
misinterpreted as replacing them. Therefore, text from 1.H bis which specifies exactly
how the checks are to be carried out has been inserted in Clause 1.4.4.2.2 bis in the UK
CD Rev E (Ref. 5).
95 I am satisfied that the final submission of the UK CD Rev E under GDA (Ref. 5) provides
adequate specification to the designer for provision of shear reinforcement. The
justification provided in ENGSGC100410 Rev D is sufficient to satisfy regulatory
expectations.
4.3.2.5 Steel Partial Safety Factors for Fastenings - ENGSGC 100395 Rev B
96 EDF and AREVA’s submission for this specific query from GI-UKEPR-CE-02.A1 is the
technical document “Steel and concrete partial safety factors for EPR™ fastening
systems” ENGSGC100395 Rev B (Ref. 39).
97 The Step 4 review of ETC-C 2006 noted that the factors of safety given for fastenings
were lower than those used in industry codes and good practice documents. Document
ENGSGC100395 Rev A was submitted as justification at that time for revised values of
the partial safety factors for the steel components of the fastenings. The concrete
material factors were consistent with those from the “Design of fastenings for use in
concrete”, Part 4 to Eurocode 2 (in development) (Ref. 29) and so were deemed
satisfactory.
98 The new steel material factors of safety proposed in AFCEN ETC-C 2010 were increased
from 1.15 to 1.4 for the normal Ultimate Limit State (ULS) and from 1.0 to 1.25 for the
accidental ULS cases. This is a significant increase but it was noted that the new factors
are still lower than those derived from Eurocode 2 Part 4 when the likely steel properties
are considered. The factors of safety are however higher than those recommended in
the CEB international good practice guide “Fastenings to Concrete and Masonry
Structures” (Ref. 27), and on this basis were deemed to be acceptable by the Step 4
review.
99 The outstanding comment from Step 4 was that the new factors are only applied to the
headed anchors and not normal bar reinforcement, which is treated as reinforcement in
accordance with Eurocode 2 Part 4 and as such would have lower factors of safety.
Reinforcement bars welded to the back of a cast-in plate will be subject to combined
tension and shear, unlike normal reinforcement. They form part of the overall safety of
the bracket and, as such, further justification was required for using lower material factors
than proposed for headed anchors.
100 ENGSGC100395 Rev B (Ref. 39) was submitted for close-out and was reviewed against
the outstanding comment (Ref. 77). The principal revision made is to state that the
proposed factors of safety apply to both headed and non-headed anchors. Since the
same factor of safety is to be applied to all anchors there are no further concerns with this
document and I consider it to be acceptable.
4.3.2.6 Prestressing Tendons Participation - ENGSGC100416 Rev C
101 EDF and AREVA’s submission for this specific query from GI-UKEPR-CE-02.A1 is the
technical document “Prestressing tendons participation in reinforced concrete
calculations for the inner containment” ENGSGC100416 Rev C (Ref. 55).

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102 The UK EPR™ inner containment structure uses bonded prestressing steel tendons. The
tendons are smooth and so have an inferior bond with the concrete than that of normal
reinforcement i.e. deformed bars. When a prestressed concrete element cracks, stresses
are induced in reinforcement and any bonded tendons, but stresses in the tendons are
less due to the inferior bond. To allow for this, the effective area of prestressing strand is
reduced by a factor in Eurocode 2, Part 1-1, known as the prestressing participation
factor. The factors in the ETC-C are higher than in Eurocode 2, and therefore the ETC-C
considers the prestressing steel to be more effective and subsequently calculates lower
reinforcement stresses.
103 The justification for the 2006 ETC-C participation factors was submitted during GDA Step
4 via ENGSGC100416 Rev A. This was satisfactory as the basis for determining the
contribution of the horizontal tendons, which are in corrugated ducts. It demonstrated
that the ETC-C was more conservative than Eurocode 2 for group 2 and group 3 load
combinations, and any discrepancies for group 1 combinations were not significant.
However, there was no discussion on the approach for vertical tendons, the approach
when tendons are in smooth ducts, or the approach close to singularities (such as major
penetrations) when stabilised cracking may not develop. Given the number of tendons in
smooth ducts and the tendency for these to be adjacent to major penetrations, which are
considered singular zones, the lack of specific rules in this area was questioned by ONR
(Ref. 32).
104 ENGSGC100416 Rev B (Ref. 40) was submitted in February 2011 but did not address
the comments, and a further revision of the document was requested. Rev C (Ref. 55)
was submitted in September 2011 and was reviewed against the previous comments
(Ref. 77). Ref. 55 presents a theoretical derivation of the participation of the prestressing
steel in smooth ducts, but the numerical examples given did not include the full
supporting calculation. However, the document also presents considerable new material
on the feedback from the construction and testing of the 900MWe series of power plants
in France. Testing was carried out on the tendons in the as-built structures of the power
plants. Experimental testing was also carried out on a ½ scale mock-up of a containment
structure at test facilities on the Civaux site, France. This mock-up is known as the
MAEVA mock-up (MAquette Enceinte en Vapeur et en Air or Steam and Air Containment
Model).
105 The research work undertaken compared the theoretical predictions of the behaviour
(e.g. cracking) of the containment structure from the FE models, with the experimental
results from the MAEVA mock-up. This provides valuable benchmarking of the predicted
behaviours.
106 The review of ENGSGC100416 Rev C found that the practical feedback and test results
presented demonstrate that the reinforcement/tendons provided result in acceptable
crack widths in the actual structures. In addition, the theoretical crack widths calculated
are relatively insensitive to the design assumptions made in terms of participation factors,
and thus use of a slightly higher factor did not affect the crack widths significantly. Given
these two points I am satisfied that the design approach used in the generic design
results in a robust structure and ENGSGC100416 Rev C is acceptable.
4.3.2.7 Shrinkage and Cracking of Concrete Structures - ENGSGC100426 Rev B,
ENGSGC100428 Rev B and ENGSGC110025 Rev A
107 EDF and AREVA submitted two updated documents in response to GI-UKEPR-CE-02,
namely “Methodology for Consideration of Shrinkage for EPR™ Concrete Structures”
ENGSGC100426 Rev B (Ref. 41) and “Verification of Crack Width for EPR™ Concrete
Structures” ENGSGC100428 Rev B (Ref. 42) and a new document “Global approach

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about methodology for consideration of shrinkage and crack limitation” ENGSGC110025

Rev A (Ref. 43).
108 Shrinkage of concrete occurs, due to various chemical and physical effects, both in the
early stages and the longer term. Where early shrinkage is constrained, for example
where a wall is cast onto a raft, the wall will want to shrink more than the raft which has
already undergone its first stage of shrinkage. The wall is therefore restrained by the raft
and internal tensile forces develop which eventually will cause cracking in the wall.
109 Crack widths are required to be controlled for various reasons including durability, water
resistance, compatibility with waterproofing membranes and aesthetics. Accepted design
codes specify the maximum allowable crack width that the structure can accommodate
depending upon its performance requirements. For the EPR™ strain compatibility of the
concrete movement with steel liners used for the assorted pools and containment is a
further consideration. The extent of shrinkage cracking in concrete is normally controlled
by a combination of concrete mix, pour sequence, curing of the pour, operating
temperatures and by the amount of reinforcement provided in the structure. Shrinkage
cracking may be considerable in high strength concrete mixes with a low ratio of water to
cement or with silica fume added, as is the case for the inner containment concrete
proposed.
110 The GDA Step 4 assessment (Ref. 2) noted that the reference design, FA3, had
exceptionally high rates of reinforcement and that this was determined by the
serviceability limit state including shrinkage, which required significantly more
reinforcement than the design earthquake. EDF and AREVA submitted two documents
during Step 4 to justify its approach to the control of cracking, ENGSGC100426 Rev A
and ENGSGC100428 Rev A. These were assessed but found to fall short of ONR
expectations. EDF and AREVA therefore submitted updates ENGSGC100426 Rev B
(Ref. 41) and ENGSGC100428 Rev B (Ref. 42) in response to GI-UKEPR-CE-02 and a
new document “Global approach about methodology for consideration of shrinkage and
crack limitation” ENGSGC110025 Rev A (Ref. 43). These three documents do not
include justification of how the liner design is affected by the control of cracking in the
concrete wall; this is justified separately and is assessed in Section 4.5.3 of this report.
111 ENGSGC100426 Rev B (Ref. 41) sets out to present the two different methods proposed
for the control of shrinkage for the UK EPR™ and justify the parameters used. The first
method, called the equivalent force or load combination method, applies shrinkage as a
thermal load; the second method calculates a specific crack width by calculating the
strains in the concrete. Rev B has stated more clearly that the strain method (second
method) will be used for all elements with additional checks using the force method (first
method). The Step 4 assessment found the strain method to be acceptable, however the
differential shrinkage should be calculated taking into account the other forms of
shrinkage including early thermal and autogenous shrinkage effects.
112 The report confirms the argument that “it is not necessary to add early age [thermal] and
autogenous shrinkage to the drying shrinkage for the calculations”. The reasoning for
this is that “the reinforcement designed for other loads can resist the imposed tension
stresses” from early thermal shrinkage and the thermal gradient will be controlled. This is
a relevant argument, but no justification is given that the reinforcement provided is
sufficient.
113 The method used for calculating crack widths due to drying shrinkage is based on
Eurocode 2 Part 2 for concrete bridges. The UK National Annex to Part 2 specifies that
the Part 1 (building structures) method should be used in preference. To justify its use of
the Part 2 method, EDF and AREVA presents results in Ref. 41 that show the Part 2

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method is more conservative than the Part 1 method for thin elements, has similar results
for the containment wall, but predicts lower shrinkage in the raft. The raft will typically be
the restraining element since it is cast first and would have already undergone its early
shrinkage. Therefore predicting lower shrinkage in the raft is conservative when
calculating the shrinkage in elements to be cast against it.
114 Overall, I am satisfied that the Part 2 strain method for calculating crack widths due to
drying shrinkage has been justified. However the omission of calculating crack widths
due to early thermal and autogenous shrinkage does not meet UK current good practice.
This is discussed further in paragraph 117 below.
115 ENGSGC100428 Rev B (Ref. 42) sets out to present the need to control cracking and
how this is achieved for the UK EPR™. Ref. 42 is now specifically for durability
requirements only and refers to ENSGC100426 Rev B for leaktightness requirements,
however there is considerable overlap between the two documents. Inconsistencies in
crack width criteria and the use of additional unconservative methods of crack control
which were present in Rev A have also been removed.
116 EDF and AREVA proposed that the outstanding comments on Ref. 41 and Ref. 42 would
be resolved by ENGSGC110025 Rev A.
117 Report ENGSGC110025 Rev A (Ref. 43) was produced to try and bring together the
requirements in Ref. 41 and Ref. 42 in a coordinated manner. I commissioned a detailed
review of this document (Ref. 79) based on the ONR comments made during GDA Step
4. In order to resolve the outstanding queries the review included independent studies on
crack width prediction using actual reinforcement ratios and section sizes from the FA3
project and compared these to acceptable crack width values. In addition, EDF and
AREVA agreed to provide some feedback from the FA3 project on measured crack
widths to provide confidence in the approach from a practical perspective.
118 The independent calculations have been undertaken by Arup on behalf of ONR and the
results are presented in Arup report 209364-10-03 (Ref. 79). Typical wall, beam and slab
sections have been examined. The independent approach has been to use the guidance
in “Early-age Thermal Crack Control in Concrete” CIRIA Guide C660 (Ref. 28), which is
relevant good practice in the UK and is referred to by the UK supporting document to
Eurocode 2, document PD6687-1:2010 (Ref. 91). This provides UK non-contradictory,
complementary information for controlling crack widths due to restrained imposed
deformations.
119 The results of this assessment have shown that, for the assumptions made, cracking is
controlled to reasonable levels by the minimum reinforcement provided. The only
exception to this is the crack control in a 500mm thick element when subjected to end
restraint. End restraint does not govern for the cases considered in the independent
review, but it is not possible to say categorically that it will not govern elsewhere in the
EPR™. Long walls subject to significant axial restraint at their end are likely to be most
at risk. It is therefore suggested that the licensee shall confirm that there are no
situations where end restraint is a governing behaviour for walls or slabs and I raise the
following assessment finding.
AF-UKEPR-CE-78: The licensee shall provide a list of the safety critical
reinforced concrete structural elements whose behaviour under shrinkage is
dominated by end restraint. The licensee shall provide justification of the
shrinkage control methods and reinforcement provided for such elements.
Required Timescale: Nuclear Island Safety-Related Concrete.

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4.3.2.8 Partial Factor for Prestressing Actions,  p - ENGSGC100402 Rev A

120 The “Justification of the Partial Factor for Prestressing Actions γ P ” ENGSGC100402 Rev
A (Ref. 44) submitted in Step 4 was judged to be satisfactory and so no further
assessment is required for closure of GI-UKEPR-CE-02.

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4.4 DETAILING PROVISIONS

4.4.1 Introduction
121 The ONR review during GDA Step 4 found that the rules given in the AFCEN ETC-C
2010 for detailing of C1 civil structures, particularly seismic requirements, were not as
specific as would normally be expected for NPP structures. EDF and AREVA proposed
in its resolution plan to produce a new document which would provide additional rules.
ENGSGC110157 Rev A, “EPR™ Safety Category 1 (C1) Structures - Good Practice
Detailing Rules for Reinforced Concrete and Steel Structures” (Ref. 45) was submitted in
July 2011. The assessment of this report is presented in Section 4.4.2 of this report.
122 The GDA Step 4 review also requested further justification of the construction joint
method specified by AFCEN ETC-C 2010. EDF and AREVA submitted a new document
“Justification of the AFCEN ETC-C Construction Joint Design Method” ENGSGC110222
Rev A (Ref. 92) in September 2011. The assessment of this is presented in Section 4.4.3
of this report since it affects how construction joints in concrete structures are detailed.
123 The use of projecting bars (bent down bars) in openings was queried by the Step 4
assessment (Ref. 2) since this is not usually permitted in the UK for nuclear structures.
This was included in GI-UKEPR-CE-01, but is assessed in this report since it is directly
specified by the ETC-C. This is presented in Section 4.4.4.

4.4.2 Detailing Rules for Reinforced Concrete and Steel Structures ENGSGC110157
124 EDF and AREVA’s final submission for this specific query from GI-UKEPR-CE-02.A1 is
the technical document “EPR™ Safety Category 1 (C1) Structures - Good Practice
Detailing Rules for Reinforced Concrete and Steel Structures” ENGSGC110157 Rev B
(Ref. 56). This updated the previous version, Rev A (Ref. 45).
125 The Step 4 assessment found that neither ETC-C 2006 nor AFCEN ETC-C 2010 referred
to Eurocode 8 (BS EN 1998) “Design of Structures for Earthquake Resistance” (Ref. 23)
for the ductile detailing of structures. Therefore, the ETC-C must provide the necessary
rules to achieve the required performance of the structure. This comment had been
previously raised in technical queries, TQ-EPR-241 and 283 (Ref. 93) and the responses
noted that “the design rules prescribed by ETC-C, and additional good practice rules
applied in the design of FA3 buildings…result in principles which comply approximately
with those for ductility class “M” as described in Eurocode 8.”
126 Eurocode 8 allows two approaches; non-dissipative structures (low ductility class) and
dissipative structures (medium or high ductility class) For the latter, the structures are
allowed to enter the plastic domain by becoming ductile, and so provided ductile detailing
is used the design loads from the elastic FE analysis model can be reduced by a factor,
q. For the former, the behaviour remains approximately elastic and no ductile detailing is
required (i.e. standard Eurocode 2 or 3 rules apply) provided the full elastic loads are
used (i.e. q =1.0).
127 EDF and AREVA’s philosophy is that since the seismic design of C1 structures of the
EPR™ is based on an elastic response (q=1) then theoretically no ductility needs to be
provided in the structural detailing. However, the responses to the TQs did not clarify
exactly what level of ductility was included to avoid brittle failure modes in beyond design
conditions and what detailing rules would be used to ensure it was achieved. Therefore
further justification was requested via GI-UKEPR-CE-02 and EDF and AREVA submitted
ENGSGC110157 Rev A (Ref. 45) in response.

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128 A review of Ref. 45 was commissioned by ONR and is presented in Arup report 209364-
10-05 (Ref. 81). The main review conclusion was that the claim of equivalence with the
ductility class “medium” (DCM) of Eurocode 8 had not been proven. The review
examined the detailing rules in Ref. 45 and found that together with AFCEN ETC-C 2010
they did not include the requirements of Eurocode 8 for a medium ductility class structure
and hence cannot be said to ensure adequate ductility. The main omission was an
identification of the system used to provide ductility but there were also particular
omissions in detailing rules.
129 ONR issued its comments on ENGSGC110157 Rev A to EDF and AREVA via letter
EPR70370R (Ref. 94) summarising the above and overall that ductility was claimed to be
provided in C1 structures but the detailing rules to be used to provide ductility had not
been proven. In response EDF and AREVA submitted a preliminary version of
ENGSGC110157 Rev B Prel (Ref. 96) and a justification report from recognised French
experts in this field on the aseismic design of reinforced concrete (Ref. 97).
130 The justification given in Ref. 97 for the EPR™ detailing rules is that NPPs are not
completely covered by the Eurocodes, which are dedicated to normal buildings and
where structural elements are much more slender than in an NPP. EDF and AREVA
have therefore provided additional requirements based on operational and construction
experience over many years. The EPR™ is designed to remain globally elastic in
accidental load cases and no specific measures for ductility are required. A second
argument given was that plastic hinge points in normal buildings can be engineered at
certain locations in the long, thin structural elements. NPPs mainly consist of
intersecting, thick and highly reinforced shear walls and so they would not yield at a
particular hinge point as envisaged by Eurocode 8 rules for medium or high ductility
classes.
131 Detailing rules for structural steelwork had not been included in Ref. 96 or Ref. 97.
Therefore, EDF and AREVA provided a subsequent response via letter EPR01108N (Ref.
98), which enclosed a justification report (Ref. 99) from the French CTICM (Centre
Technique Industriel de la Construction Metallique i.e. Steel Construction Institute). This
expert report, again argues that if fully elastic design is adopted, then ductile detailing for
steelwork is not required. It states that:
 The higher the safety requirements used to design a building under seismic loading,
the less it becomes possible to resort to plastic dissipation and therefore the
principle of dissipative behaviour.
 The requirements of Eurocode 8 for standard buildings allow for the use of ductility
classes DCM or DCH, leading to the optimisation of the design with the risk of
irreversible damage to the structure under seismic loading.
 Special buildings such as nuclear power plants, need to remain operable after an
earthquake (therefore excluding all damage) and shall be designed with a ductility
class of DCL, or even with q=1 regardless of their location.
132 Ref. 99 confirms that the same philosophy is used for C1 steelwork structures of the UK
EPR™ as for the concrete structures. Therefore, the additional detailing rules for
steelwork structures are based on Eurocode 3 and EPR™ feedback experience.
133 EDF and AREVA submitted the revised report ENGSGC110157 Rev B (Ref. 56) in May
2012. This update clarified that the design of C1 structures is based on non-dissipative
behaviour and that the analogy with medium ductility structures is no longer claimed. It
also makes clearer that detailing rules are not based on Eurocode 8, but on Eurocodes 2
and 3, with enhancements required for special structures such as NPPs. This document

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is to be used in conjunction with the detailing rules given in the UK Companion

Document. The final submitted version of the UK CD Rev E (Ref. 5) has included the
above detailing rules in Clause 1.4.11.1 bis Reinforcement and 1.7.2.2 bis Seismic
Detailing.
134 I am satisfied that designing the UK EPR™ C1 civil structures for the full elastic loads at
design basis is appropriate such that the structures remain operable after an earthquake.
The question is how the structures behave if subject to a beyond design basis
earthquake, i.e. at what margin do plastic hinges form and is there a possibility of brittle
(sudden) failure. EDF and AREVA has provided seismic margin assessments for the
containment and massive concrete structures and demonstrated there is sufficient margin
for the generic design (Ref. 2, Section 4.3.10.3). The beyond design basis behaviour of
the inner containment has also been assessed by ONR under GI-UKEPR-CE-03 (Ref. 8).
Therefore, I am satisfied that the design approach in ENGSGC110157 Rev B (Ref. 56) is
adequate for such massive concrete structures, which form the majority of the Nuclear
Island.
135 I accept the argument that ductile hinges do not tend to form in discrete locations in
massive concrete sections and so ductile detailing is not necessarily relevant. However,
for smaller structural elements, such as small section concrete columns or steelwork
supports the possibility of ductile hinges forming needs to be appraised by the designer. I
accept that at the design basis earthquake the sections remain elastic; but as the loads
increase beyond this level it should be proven that at the target margin any plasticity in
these sections does not cause sudden failure. No evidence has been submitted to justify
this beyond design basis behaviour. Since ductile detailing rules have not been adopted
for these types of sections the substantiation required at detailed design phase will be
more onerous. The Step 4 report (Ref. 2) raised Assessment Finding AF-UKEPR-CE-66
requiring the licensee to demonstrate that adequate margins beyond the design basis
exist for all Class 1 civil structures. I raise the following assessment finding to
supplement this requirement, specifically with respect to ductile behaviour in a beyond
design basis event.
AF-UKEPR-CE-79: The licensee shall confirm that there is adequate
margin beyond design basis for safety critical non-massive structural
elements e.g. concrete columns or steel frames, such that if plasticity occurs
in any part of those elements for the event considered, this will not lead to
sudden failure.
Required Timescale: Nuclear Island Safety-Related Concrete.

4.4.3 Construction Joint Design Method - ENGSGC110222 Rev A

136 During the GDA Step 4 review ONR requested further justification of the construction joint
method specified by AFCEN ETC-C 2010. This request was agreed at the technical
workshop in July 2011, and included as part of GI-UKEPR-CE-02. EDF and AREVA
submitted a new document “Justification of the AFCEN ETC-C Construction Joint Design
Method” ENGSGC110222 Rev A (Ref. 92) in September 2011.
137 I commissioned Arup to carry out a review and the findings are presented in report
209364-10-02 (Ref. 78). ENGSGC110222 Rev A sets out to justify the method of shear
joint design in the AFCEN ETC-C 2010. It proposes to do this by reference to the
American Concrete Institute (ACI) concrete design codes ACI-349, “Code Requirements
for Nuclear Safety Related Concrete Structures” (Ref. 24) and ACI-318, “Building Code
Requirements for Structural Concrete” (Ref. 25) and with reference to test data.

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138 The key findings from the review (Ref. 78) are:
 The shear joint equation in the AFCEN ETC-C 2010 code is not consistent with the
level of joint preparation proposed
 The document contains improved definitions of the key variables in the shear joint
equation.
 The comparison with the ACI approach shows that the ETC-C approach is generally
less conservative, with margins up to 25% (typically 15%). The document reviewed
does not attempt to justify or discuss this. Furthermore, no comparison of the
loading to be applied is considered. It would appear that the loading to ACI 318
would be higher, additionally reducing the relative safety of the AFCEN ETC-C
2010, and this should be further investigated.
 Data from 10 tests are presented that demonstrate the AFCEN ETC-C 2010
designed sections have a substantial margin between actual capacity to calculated
capacity. However, the relevance of these tests to the wide range of situations that
are covered by the shear joint equation is not considered.
 The joint in the dome roof of the containment is a special case, since it is within its
thickness, and this situation is not explicitly covered.

139 In conclusion, ENGSGC110222 Rev A did not justify that the method given in the AFCEN
ETC-C 2010 was equivalent to, or better than, the method in Eurocode 2. ONR also
stated that should a construction joint fail to meet the requirements of Eurocode 2, then
the position of that joint should be reconsidered.
140 The technical aspects were discussed with EDF and AREVA at the technical meeting
November 2011. EDF and AREVA proposed new design rules for construction joints
from one of the following options.
1) Provide further justification of the method proposed in AFCEN ETC-C 2010,
2) Provide case by case justification for situations where Eurocode 2 rules are not
satisfied, or
3) Transfer the justification for a comprehensive methodology to site specific phase.
141 In January 2012, EDF and AREVA proposed a revised approach using option (2) above
via letter EPR01060N (Ref. 100). Clause 1.4.4.2.2 bis - Shear of the UK CD Rev E (Ref.
5) has been revised to the following:
142 “The design of construction joints shall be verified against the criteria set out in EN 1992-
1-1 clause 6.2.5, conservatively using the parameters given for rough surfaces. Where
these criteria are not met, justification of the construction joint design shall be made on a
case by case basis, submitted to the licensee’s Design Authority approval.”
143 I am satisfied that this change in approach will result in adequate design of construction
joint details. Eurocode 2 Part 1.1 (BS EN 1992-1-1) is accepted good practice and any
deviation from this will be justified on a case by case basis during site specific design. A
specific joint sampled during Step 4 GDA was that in the domed roof to the inner
containment. The clarification that this will comply with Eurocode 2 rules has answered
the design queries raised. However, during the phased construction this joint needs to be
kept partially complete and so its protection and preparation for the next concrete pour is
a workmanship issue which is outside the scope of GDA. I have therefore raised the
following assessment finding.

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AF-UKEPR-CE-80: The licensee shall provide the final construction

specification and details for the joints within the concrete dome roof to the
inner containment, and justify that the finished structure will fulfil the nuclear
safety requirements.
Required Timescale: Install Polar Crane.

4.4.4 Bent Down Bars

144 When an opening is formed in a concrete structure, one technique is to bend the
reinforcing bars to avoid having to form holes for them in the formwork. This is not
generally permitted in the UK for nuclear structures, and only for small diameter bars in
normal structures. This is to avoid the possibility of the bars being overstressed when
they are bent back after casting.
145 ONR raised this as a comment in letter EPR70367R (Ref. 34) under Section 2.4
“Reinforcement for Reinforced Concrete”, and it is listed as comment 2-16 in the ETC-C
Tracking Spreadsheet (Ref. 13). The use of bent down bars was permitted in the
Flamanville 3 “Hypothesis Note on Reactor Building Containment Internals” and so this
was queried under GI-UKEPR-CE-01 (Ref. 7, Section 4.2.3.16).
146 EDF and AREVA has confirmed that Clause 2.4.5.3.3 of the AFCEN ETC-C 2010 (Ref. 4)
controls the site bending of bars as follows:
“The re-straightening, even in part, of a bent reinforcement is not permitted except
for reinforcements which have a certificate of conformity for re-straightening after
bending, supplied by an approved and notified certification body.”
147 I consider this as a satisfactory response to this comment and so consider it closed.

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4.5 POOL LINER DESIGN

4.5.1 Introduction
148 The concrete in both the inner containment and the pools is faced with a steel liner. The
purpose of these liners is to ensure leaktightness; they do not contribute to the structural
strength. The liners are attached to the concrete by various means, including studs and
welded angles, such that forces are transferred between the two.
149 The Step 4 review of the AFCEN ETC-C 2010 concluded that this code itself did not
provide sufficient guidance in Clause 1.6 for the design of steel lined pools and tanks of
the EPR™. Therefore, the production of a methodology document(s) was required which
properly explains the detailed design and construction process for these structures.
150 The EDF and AREVA Resolution Plan for GI-UKEPR-CE-02 listed the “Methodology
Report for Pool Liners” as a deliverable, but the document number was not known at that
time. The resulting documents submitted were:
 “Pool Liner Design Requirements and Methodology” ENGSGC110243 Rev A (Ref.
46), and
 " UK EPR™ – GDA – Presentation and Justification of the Consequences of
Concrete Cracking on Liner Leak-tightness" ENGS110046 Rev A (Ref. 101).
151 Ref 46 was submitted as the primary methodology document for the design process for
liners of pools and tanks of the UK EPR™. This is assessed in Section 4.5.2 below. Ref.
101 was submitted as additional justification for the treatment of liner strains due to
concrete cracking. This affects the inner containment as well as pool liners; therefore I
have included the assessment here since the technical issues are the same. Ref. 101 is
assessed in Section 4.5.3 of this report.

4.5.2 Methodology for Pool Liner Design - ENGSGC110243

152 The initial deliverable ENGSGC110243 Rev A (Ref. 46) was submitted at the start of
GDA Issue Close-out in August 2011. ONR commissioned Arup to carry out an
assessment of this report for GI-UKEPR-CE-02 and the conclusions are presented in
Arup report 209364-10-11 (Ref. 86). ONR comments were issued to EDF and AREVA
via letter EPR70366R (Ref. 102) in October 2011.
153 The main comment was that the document did not greatly extend the specification for the
methods to be used for the design and construction of steel lined concrete pools and
tanks. There was also insufficient guidance on the design of the leak collection system
and the design of sluice gates. The context of the document within the generic design
was also unclear. Finally, the roles and responsibilities of the generic designers and the
site specific design contractors needed to be made clearer.
154 EDF and AREVA provided a preliminary Rev B to ENGSGC110243 (Ref. 103) in
response to the comments in the ONR letter. This was intended to provide an overall
methodology to support Section 1.6 of the AFCEN ETC-C, and hypothesis notes for each
specific structure would be created during the site specific phase in line with this
methodology.
155 ONR commented (Ref. 104) that the proposed Rev B of the document was a significant
improvement on the previous version in that it included more detail on the design
process. Two further technical comments were also made: firstly that Section 5.1
included a statement that there is "no specific leak tightness requirement associated with
the concrete structures" and secondly that Section 6.5 needed clarification on the non-

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linear FE models used. For the former, Assessment Finding AF-UKEPR-CE-28 had
already been raised in the ONR GDA Step 4 report (Ref. 2) which said "The licensee
shall confirm that the concrete portion of all steel lined concrete pools which have a
permanent and potentially contaminated fluid shall be confirmed as adequate against the
requirements of BS EN 1992 Part 3 (Tightness class 1)". This means that the concrete
will be designed to limit cracking such that it provides an additional line of defence
against leakage.
156 ENGSGC110243 Rev B (Ref. 57) was submitted in March 2012 and an explanation given
in letter EPR01114N (Ref. 105) of how the ONR comments had been addressed. The
responses to the points raised are detailed below.
157 Further details have been added to Ref. 57 to provide liner plate thicknesses and
anchoring design guidelines with reference to Section 1.8 of AFCEN ETC-C 2010 for the
interface requirements between anchors and concrete. The method for treatment of
discontinuities and the requirements for leak detection systems and sluice gates have
also been expanded. The minimum reinforcement requirements for crack control in the
concrete are referred to in Section 5.1. Guidance for the FE models has also been added
at several points in Section 6 “Design Codes and Methodology”.
158 The additional technical details that have been added to Ref. 57 are sufficient to answer
the ONR comments raised on the first version of the document. However, it should be
noted that the specific detailed design criteria and requirements will be developed further
at site specific phase. There is already a Step 4 regulatory requirement for justification of
this design hypothesis at that time which is captured by Assessment Finding AF-UKEPR-
CE-17 (Ref. 2). Likewise, justification of the testing of pools and leak detection systems
to prove their adequacy is required under AF-UKEPR-CE-18.
159 The methodology document (Ref. 57) states that it “marks the end of the GDA phase and
site specific hypothesis shall be created in line with this report.” The description of the
design process, in terms of responsibilities is given in the “EPR Nuclear Island Civil
Engineering Design Process Note” (Ref. 60) which has clarified that the detailed design
will be based on the hypothesis notes produced by the civil works designers. I am
satisfied that this approach ensures they take ownership of the design, under the
supervision of the licensee’s Design Authority, but also that their specialist knowledge
can contribute to the final detailed design specification.
160 The detailing and construction specifications will be finalised during the site specific
phase. This aspect was an exclusion from Step 4 (Ref. 2) and so is not included in the
generic pool liner methodology. This is satisfactory and will allow assessment of the
specifications at the appropriate time as required.
161 The resulting document submitted ENGSGC110243 Rev B (Ref. 57) is acceptable as a
response to GI-UKEPR-CE-02 in terms of providing a generic methodology which will be
used to produce the site specific design hypothesis documents. It has addressed the
technical ONR comments raised or, where these cannot be answered until detailed
design is in progress, has provided an approach by which it will be achieved. This has
been captured in the Step 4 report by Assessment Finding AF-UKEPR-CE-17 by
requiring the licensee to produce a hypothesis note for the pool liner design at site
specific stage.

4.5.3 Liner Performance subject to Concrete Cracking - ENGS110046

162 EDF and AREVA submitted a new document, in September 2011 in response to
GI-UKEPR-CE-02, titled " UK EPR™– GDA – Presentation and Justification of the

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Consequences of Concrete Cracking on Liner Leak-tightness" ENGS110046 Rev A (Ref.

101). This document aims to justify the anchor spacing adopted for both the inner
containment and pool liners, with reference to results of experimental testing carried out
on scale models of containment structures.
163 When cracks form in the concrete wall supporting the liner, all the movement at the crack
needs to also be accommodated in the liner, and so high strains could be generated in
the liner. During GDA Step 4, ONR sought evidence that the design of liners and
anchors into the concrete ensured that the liners would remain leaktight for the design
basis and with sufficient margin. However, it was concluded that the treatment of
concrete cracking in the calculation of liner strains needed further justification.
4.5.3.1 Pool Liner Strains
164 The review of ENGS110046 Rev A (Ref. 101) was carried out by Arup on behalf of ONR.
The conclusions are reported in Arup report 209364-10-04 (Ref. 80). Ref. 101 states it
has been written in order to describe and justify how concrete cracking is taken into
account in the design of liners and their anchorage systems. It discusses this effect and
notes that both local and global testing has been carried out to investigate the issue.
165 Ref. 101 states that for the pool liners, concrete cracking is accounted for by limiting the
distance between anchors such that the liner is not over stressed and so leak tight
behaviour is maintained. Section 7 describes the analysis and design of pool liners
carried out using the ETC-C. The calculation of the localised strain in the liner was
related to the concrete crack width limit, but the exact basis of the calculation was
unclear.
166 EDF and AREVA submitted an updated version of ENGS110046 Rev B (Ref. 106) under
cover of letter EPR01114N (Ref. 105). This has an additional section 7.2 on the
“Concrete Leak Tightness via Crack Width Limitation” which details how the crack width
and crack spacing is limited by the reinforcement provided in the concrete. Eurocode 2
Part 3 is used for this calculation, but with additional specific measures as specified by
ETC-C and its UK CD. This results in the liner anchor spacing being approximately 20%
of the crack spacing in order for the strain in the liner to be below 4.5% which is the
requirement for austenitic stainless steel.
167 On this basis, I am satisfied that the strain in the pool liner will be controlled by the anchor
spacing combined with the reinforcement provided in the concrete to control cracking.

4.5.3.2 Inner Containment Liner

168 ENGS110046 Rev B (Ref. 106) also presents evidence on how experimental testing is
used to benchmark the design of the containment liner carried out to ETC-C. Since this
is also used to justify the arguments for pool liners, it is discussed below.
169 The experimental tests for the containment liner presented in the first issue of
ENGS110046 Rev A (Ref. 101) were undertaken by Sandia National Laboratory in the
US on behalf of the US Nuclear Regulatory Commission (NRC). Two specially built scale
models were tested. These models were
 Sandia I - a 1:6 scale model of a reinforced concrete containment building, and
 Sandia II - a 1:4 scale model of a prestressed concrete containment building.
170 EDF and AREVA drew the following conclusions in Ref. 101 from these tests.

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 “Code criteria have a large margin for both structural capacity and liner leak
tightness”.
 “The failure mode is a leak before break due to liner tearing”.
 “The liner tearing is due to a localisation effect”.
171 ONR issued comments to EDF and AREVA (Ref. 107). These were that overall the
design approach was adequate and had been benchmarked by the tests. The
interpretation of the scale test data was queried, since statements made on the differing
responses of reinforced concrete versus prestressed concrete needed further discussion.
The liner strain limits in the AFCEN ETC-C 2010 had been changed from the 2006 ETC-
C to be the same as those in the ASME III Div 2 Code for concrete containments (Ref.
26). The equivalence of these strain limits was queried and how the average strain is
calculated.
172 The updated version of ENGS110046 Rev B (Ref. 106) confirmed that “a major difference
between reinforced and pre-stressed concrete is that tension (and consequently cracking)
occurs earlier in the case of passive reinforcement, which is important for determining the
design pressure level. Comparing test results helps illustrate the differences between the
concepts:
 For Sandia I (reinforced only): rebar and liner yielding occurred at 0.86 MPa, i.e. a
little before the leak, which occurred at 0.875 MPa.
 For Sandia II (pre-stressed): rebar yielding occurred a little before the leak, which
occurred at 0.97 MPa.
in both cases leakage occurred far beyond the design pressure (2.69 Pd and 2.5 Pd).”
173 The above test results demonstrate that the pre-stressed containment could resist a
higher pressure before it cracked than did the reinforced containment, due to the fact its
reinforcement is not “passive” and has applied a pre-compression in the concrete before
testing. The response has given adequate additional information on the nature of the
failure observed in the Sandia tests, and confirmed that both failures occurred at
significant margins beyond the design pressure. Ref. 106 also gave a comparison
between the ASME code and the ETC-C for liner design, and how the Sandia test
structures differed from the UK EPR™ design in terms of loading and fabrication. This
has confirmed that the liner design margin, based on the Sandia results in a beyond
design pressure scenario, remain applicable to the EPR™.
174 The justification for adopting the ASME III strain limits in the AFCEN ETC-C 2010 was
that the former is an internationally recognised standard and these strains limits had been
approved by the US Nuclear Regulatory Commission (US NRC) in its assessment of the
Sandia tests. The updated AFCEN ETC-C 2010 document had therefore included the
ASME III strain limits as relevant to the EPR™ design.
175 I consider the above as adequate justification that the liner design gives sufficient margin
above the design basis pressures for the inner containment.

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4.6 DROP LOAD ANALYSIS

4.6.1 Introduction
176 The Step 4 GDA assessment found a shortfall in the methodology for assessing impact
damage on civil structures from dropped loads and internal missiles. Therefore, GI-
UKEPR-CE-02 also includes a requirement for an adequate dropped load methodology
document to be produced and justified.
177 Section 1.4.7 of AFCEN ETC-C 2010 (Ref. 4) details the requirements for design of
concrete structures for impacts from internal projectiles and dropped loads. This simply
states that “in the case of internal projectiles and dropped loads, calculations may be
made with a special study. The methods defined in APPENDIX 1.C and APPENDIX 1.D
are acceptable to check the design resistance of reinforced concrete structures against
perforation by hard projectiles and against punching shear.”
178 The methods in Appendices 1.C and 1.D are very simplistic and no justification was given
that they are applicable to all dropped load or missile scenarios. The Step 4 civil
engineering assessment of the ETC-C commented via letter EPR70304N (Ref. 33) that “It
is not clear what the role of these appendices is in the design process. It is understood
that they are used as initial scoping calculations and not for the final design.”
179 The Step 4 Internal Hazards assessment report (Ref. 108) also concluded that the
treatment of dropped loads and internal missiles within the design were not adequate.
For dropped loads this primarily concerned the identification of dropped load scenarios
and production of a dropped load schedule for the design of structures. The assessment
also queried EDF and AREVA’s claim that RCC-M classified vessels, pumps, tanks and
valves would not generate internal missiles since they were designed for ‘no-break’. As
a result, GDA Issues GI-UKEPR-IH-01 (Ref. 69) and GI-UKEPR-IH-04 (Ref. 70) were
raised in the internal hazards topic area, with specific actions which interrelate with Civil
Engineering
180 GI-UKEPR-IH-01.A2 Substantiation and analysis of the consequences of dropped
loads and impact from lifting equipment included within the
EPR™ design. Provide a description of the approach taken to
treat dropped loads on civil structures.
181 GI-UKEPR-IH-04.A1 Consequences of missile generation arising from failure of
RCC-M Components. Provide substantiation of the claims
made within the PCSR associated with the preclusion of missile
generation from failure of RCC-M components which are not
designated as High Integrity Components (HIC) as defined in
the consolidated PCSR. In particular justify the analysis of the
consequences of failure.
182 This section presents the civil engineering assessment of the dropped load methodology
(Section 4.6.2) and my assessment of how that methodology has been applied to civil
structures for certain internal missile scenarios (Section 4.6.3).

4.6.2 Dropped Load Methodology – ENGSGC100483

183 The final submission of the document “Methods with regard to the risk of dropped loads
for EPR™ UK for civil works structures”, ENGSGC100483 Rev B (Ref. 58) was submitted
in March 2012.

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4.6.2.1 Progress of the Assessment

184 The initial response from EDF and AREVA, specific to the dropped load methodology for
civil structures, was report “Methods with regard to the risk of dropped loads for EPR™
UK for concrete structures” ENGSGC100483 Rev A (Ref. 47). This was submitted in
June 2011 and was a resolution plan deliverable under GI-UKEPR-CE-02.A1 and A2 and
also GI-UKEPR-IH-01.A2.
185 The ONR assessment was supported by ABS Consulting Ltd (ABSC) who carried out a
technical review of ENGSGC100483 Rev A. The ABSC review is summarised in report
2120812-R-07, “Review of GDA Issue on Dropped Loads EPR™ Report
ENGSGC100483 Rev A” (Ref. 109). The significant aspects of this review are discussed
below.
186 Comments on ENGSGC100483 Rev A were issued to EDF and AREVA in August 2011
(Ref. 110). These comments were discussed with EDF and AREVA at the civil
engineering technical meetings and convergence was progressed via staged responses
to these comments. EDF and AREVA provided a response to each of the ONR
comments via letter EPR01098N (Ref. 111) and an updated version of ENGSGC100483
at Rev B (Ref. 58) in March 2012.
4.6.2.2 Assessment
4.6.2.2.1 Scope of Methodology
187 Rev A of the methodology document (Ref. 47) was a 30 page report which comprised a
collection of a number of different methods to assess impact of dropped loads on
concrete structures. The abstract stated that “The current design report has been written
in order to verify that the civil engineering structures of the nuclear island are robust
enough to withstand "dropped loads".…..It provides the principles of methods to check
concrete structures for the UK EPR™.” It was therefore not applicable to any other type
of structure, e.g. steelwork and not applicable to assessment of damage to plant and
equipment from these dropped loads.
188 The title of the ENGSGC100483 Rev B (Ref. 58) has been changed to “Methods with
regard to the risk of dropped loads for EPR™ UK for civil works structures”. A section
had also been added to include dropped load assessment of steel civil structures.
Therefore, the methodology is now applicable to both concrete and steel civil structures
and I am satisfied with this scope.
189 Ref. 58 explicitly excludes any methods on how to assess the damage that may be
caused to the dropped item. For instance, if the dropped load is a package containing
nuclear material its integrity following the event would need to be adequate to satisfy the
safety case. EDF and AREVA’s response was that the safety significance of the dropped
item is considered in the safety assessment for each scenario and the design of the
package would be based on the safety functional criteria required. I agree that
assessment of damage to packages is outwith the scope of the civil engineering topic
area and so this has not been sampled further.
4.6.2.2.2 Methods
190 The methods presented in Ref. 47 to assess the damage to concrete structures were split
into three categories:
 Part 1: Punching Shear - three methods are included for punching shear, i.e.
whether the dropped load would punch through a concrete structure.
 Part 2: Bending verification - four methods are included for checking whether the
bending induced in the concrete structure by the impact could cause global failure.

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 Part 3: Punching and bending verification - two methods are included for the
combined effects. The second method is detailed finite element dynamic modelling
of the target and of the dropped load.
191 Section 7, Principles, of Ref. 47 indicates that the methods proposed vary in complexity
and the intention is that the first stage of analysis is to use a simple, conservative
method. If this proves to be too conservative, then a more exact method can be chosen
until a realistic conclusion is reached. I consider this graded approach to be a
reasonable, engineered solution. However, there was no guidance on which methods
are the simplistic ones and which are the more exact; although the FE dynamic modelling
in Part 3 is recognised as an exact approach. Ref. 47 also gave no guidance to the
designer on how to select the most suitable method.
192 EDF and AREVA’s response to this ONR comment (Ref. 111) clarifies that both the
punching and bending checks must be carried out for each dropped load scenario.
ENGSGC100483 Rev B (Ref. 58) also provides a revised Section 7 to offer further
guidance. However there is still a shortfall since the guidance does not stipulate whether
there are any restrictions on the combinations of the methods in Parts 1 and 2, i.e.
whether all three methods in Part 1 can be used in any combination with those in Part 2.
I therefore raise an assessment finding to capture this shortfall as follows:
AF-UKEPR-CE-81: Where separate methods are used to check the
punching shear and the bending stresses in concrete civil structures induced
by potential dropped loads or internal missiles, the licensee shall justify that
the methods are compatible with one another.
Required Timescale: Nuclear Island Safety-Related Concrete.
193 The ABSC review also compared the methods in Ref. 47 with the R3 Impact Assessment
procedure (Ref. 112). The R3 methodology is accepted as current good practice for
dropped loads within the UK nuclear industry. This was developed by Magnox Electric
plc and is currently used on UK nuclear power plants. R3 comprises a series of different
calculation methods, which are applicable in different situations. EDF and AREVA
presented comparative calculations between its methodology document and R3 and
demonstrated that both methods achieved similar results. Although this study does not
justify the UK EPR™ methodologies for the full range of dropped loads, it is a useful
benchmark for the particular cases considered.
194 EDF and AREVA’s response was to add the R3 methodology as another applicable
method to ENGSGC100483 Rev B (Ref. 58). This will allow civil works designers in the
UK to use this comprehensive methodology with which they are already familiar. I concur
with the decision to include the R3 methodology since this, along with detailed FE
analysis are sufficient to cover the range of dropped loads that are applicable to NPPs.
4.6.2.2.3 Range of Dropped Loads
195 Rev A of the methodology document does not specify the range of drop loads that are
included or whether the various methods are dependent on the type of missile. In
applying recognised techniques such as R3, some knowledge of the missile type and
target type must be known before the assessment can be undertaken. The description of
dropped loads would be expected to include the following:
 Minimum and maximum weight
 Drop height, or maximum impact velocity
 Material of drop load

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 Nature of drop load, e.g. stiff or soft, pointed or blunt impact point.
196 The dropped load methodologies given in Ref. 47 do not specify the limits of their
applicability with respect to the above. The examples presented therein are all for
smaller masses of dropped loads (<340kg). The examples given in responses to TQ-
UKEPR-500 and TQ-UKEPR-669 (Ref. 93) are for much heavier masses (>45te) which is
to be expected since these were for loads lifted by the polar crane.
197 In order to provide more evidence of the range of drop loads that can occur, and a
demonstration that the methodologies proposed are suitable for their assessment the
new Section 3 in Ref. 58 provides the scope of applicability, and Section 8 provides the
validity range of postulated dropped loads. Letter EPR01098N (Ref. 111) also clarified
that the methodology “will not include a specific listing of all postulated dropped loads.
Instead this report is intended to provide generic guidance on how postulated dropped
loads will be treated. Post-GDA, it is the responsibility of the licensee to provide a
complete listing of loads to be considered”.
198 Sub-chapter 13.2 of the March 2011 PCSR (Ref. 6) argued that no dropped loads could
occur from classified cranes such as the polar crane. The failure of Higher Requirements
(RS1) and Additional Requirements (RS2) lifting equipment was screened out by its low
frequency. This then meant that potential dropped loads would only be considered for
smaller loads from lifting equipment which is non-classified. This was challenged by the
Internal hazards Inspector during Step 4 GDA and lead to GI-UKEPR-IH-01.
199 EDF and AREVA have now revised Sub-chapter 13.2 to Issue 05 (Ref. 115) and this
includes consideration of bounding cases for dropped loads from RS1 and RS2 cranes.
This has been assessed under the close-out of Internal Hazards (Ref. 116) and found to
be a satisfactory response to GI-UKEPR-IH-01. This has meant that the dropped load
methodology document has had to include methods that are applicable to heavier loads,
and with the addition of R3 along with the use of FE models I am satisfied that
ENGSGC100483 Rev B has adequate methods included in order to assess damage from
these heavy loads. The remnant shortfall is that the methodology still does not specify
when the other methods can be used. I therefore raise an assessment finding as follows,
AF-UKEPR-CE-82: The licensee shall justify that the calculation methods
used to assess the damage to civil structures due to impact from potential
dropped loads or internal missiles, are applicable to the range of dropped
loads or missiles identified by the safety assessment for that structure.
Required Timescale: Nuclear Island Safety-Related Concrete.
4.6.2.2.4 Target Properties
200 The review of ENGSGC100483 Rev A sampled the concrete properties and partial safety
factors for the target structure used in the example calculations. These were found to be
taken from Eurocode 2 (Ref. 21) which is consistent with the design code AFCEN ETC-C
2010 (Ref. 4) which also uses Eurocode 2. I am satisfied that these properties are
applicable to dropped load scenarios, and although Eurocode 2 is not specifically written
for nuclear power plants, it is applicable in this case.
4.6.2.3 Assessment Conclusions
201 ENGSGC100483 Rev B has been included as a reference to the UK Companion
Document to the ETC-C, Rev E (Ref. 5) and to the new document “EPR Nuclear Island
Civil Engineering Design Process” (Ref. 60) which is a deliverable under GI-UKEPR-CE-
01 (Ref. 7) as well as GI-UKEPR-CE-02.A2 to A4. This document is known as the
Design Process Note and is an overarching document for the civil works design and sets

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out the hierarchy of the civil design specification documents, called hypothesis notes,
which are produced for each civil structure. The exact dropped load scenarios, loads and
assessment methods will be agreed between the licensee and civil works designer at the
start of design, and documented in the hypothesis notes.
202 The revised dropped load methodology document does provide additional detail guidance
to the designer and is now a major reference to the UK CD. The Design Process Note
provides the context within which the methodology will be used. There are, however, two
shortfalls in the techniques within the methodology and I have raised Assessment
Findings AF-UKEPR-CE-81 and AF-UKEPR-CE-82 to capture these.

4.6.3 Impacts on Civil Structures from Internal Missiles - ECEIG091634 Rev B1

203 EDF and AREVA submitted document ECEIG091634 Rev B1 (Ref. 117), “EPR™ –
Internal missiles – Risk assessment report on building structure and layout” to
demonstrate and justify its methods for assessing damage from internal missiles. This
was submitted in June 2011 as a deliverable under GI-UKEPR-IH-04. My assessment
work undertaken in support of the Internal Hazards Inspector was to review this
document and in particular the calculations included in the appendices. This document
details the potential internal missiles identified for the Nuclear Island on the Flamanville 3
(FA3) nuclear power plant, and is given as an example of the approach proposed for UK
EPR™ My assessment has sampled the methods for calculating perforation to concrete
structures from missiles generated by valves.
4.6.3.1 Overview
204 ECEIG091634 Rev B1 identifies two sources of missiles which are able to generate
internal missiles potentially threatening to plant safety. These are shown below with the
claims made in the document for each:
 Missiles coming from failure of rotating equipment

 Most ruled out due to design measures to the plant.

 Disintegration of reactor coolant pump flywheels – ruled out on material specs/
design, manufacture and inspection.
 Missiles projected by the turbine - ruled out on probabilistic basis.
 Missiles coming from failure of high energy components

 Ejection of control rods.

 High energy valves of quality Q1/Q2/Q3 with wall separation.
 High energy valves of quality Q1/Q2/Q3 not physically separated.
 High energy valves of quality <Q3 – calculation given in Appendix 1.
 Unclassified high energy tanks – none in C1 buildings.
 Potential missiles on the large debris baskets of the IRWST.
205 The methodology for calculating the perforation to civil concrete structures from internal
missiles is given in Appendix 1 of Ref. 117. The results of the calculations to check
perforation of missiles generated by valves are given in Appendix 2, and those generated
by tanks are given in Appendix 3.
4.6.3.2 Assessment of Methods
206 Appendix 1 uses first principles from physics to work out the impact velocity of the
missiles. This can be used for both missiles or dropped loads since it is based on initial

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velocity and acceleration, which would be zero and gravity in the case of a dropped load.
I am satisfied that the equations used are appropriate and have been correctly applied.
207 Appendix 1 then gives two methods for checking whether a concrete wall or slab would
be perforated by the missile.
 ETC-C 2006 (Ref. 30) Appendix 1.D, “Penetrations of Reinforced and Prestressed
Concrete Slabs by Hard Missiles”
 LI Criterion – based on a method from the International Journal of Impact
Engineering.
208 Both of the above methods are included in the dropped load methodology document
ENGSGC100483 Rev B (Ref. 58). Therefore, the impact damage to concrete walls
resulting from either dropped loads or internal missiles is treated in the same way. This is
appropriate since the methods rely on the velocity at impact and not the direction of
impact. However, the nature of the dropped load or missile i.e. pointed or blunt has not
been considered. This shortfall will need to be justified by the licensee as required
already by AF-UKEPR-CE-82.
209 ECEIG091634 Rev B1 states that there is a separate internal missile methodology but it
is not clear how this interfaces with the dropped load methodology. Technical query TQ-
EPR-1606 was raised to query this. The response from EDF and AREVA (Ref. 118)
stated that “ECEIG091634 B1 is a safety analysis associated with EPR™ FA3. A
dedicated safety analysis for the “missiles” hazard will be carried for the UK EPR™ at
detailed design stage. EDF and AREVA confirm that a review will be carried out to
ensure that this dedicated study is consistent with the methodology ENGSGC100483”.
The response also confirms that for FA3 a separate internal missile methodology
document (referred to in ECEIG091634 Rev B1) was produced which “sets the rules of
study for the “missiles” hazard for the EPR™ FA3, it recalls: safety objectives, establishes
the rules to identify aggressors and targets and refers to Appendix 1.D from ETC-C for
civil engineering calculations”. This internal missile methodology will be updated at
detailed design phase for UK EPR™.
210 Therefore, I am satisfied that the validity of the calculation methods within both
ECEIG091634 Rev B1 and ENGSGC100483 Rev B will be independently confirmed by
the separate internal missile methodology document. However, since the internal missile
methodology document will not be available until site specific phase I raise the following
assessment finding:
AF-UKEPR-CE-83: The licensee shall develop an internal missile
methodology document for the site specific design, and clarify how it
interfaces with the dropped load methodology document. The licensee shall
also, having indentified the range of potential missile impacts for a particular
civil structure, justify that the calculation methods used to assess the impact
on civil structures from internal missiles are applicable.
Required Timescale: Nuclear Island Safety-Related Concrete.
211 The ETC-C 2006 referred to is now superseded by AFCEN ETC-C 2010 (Ref. 4). The
equation given in Appendix 1 is the same as Equation 1.D-2 in Ref. 4 albeit rearranged.
The validity range in Appendix 1 is not the same as Ref. 4 in that it is missing two out of
the five validity criteria namely, compressive strength of concrete and symmetry of
reinforcement. TQ-EPR-1606 also queried these differences. The response from EDF
and AREVA (Ref. 118) was that ECEIG091634 Rev B1 is specific to FA3 and so used the

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ETC-C current at that time, however “we have checked that the formula presented in
report ECEIG091364 rev. B1 Appendix 1 §2.2 is the same as in version 2010 of ETC-C”.
212 The licensee will need to justify the calculations carried out at site specific phase are in
accordance with AFCEN ETC-C 2010. This is already captured by the Step 4
Assessment Finding AF-UKEPR-CE-07 (Ref. 2).
4.6.3.3 Assessment of Calculations
213 The calculations presented in Appendix 2 of ECEIG091634 Rev B1 were sampled in
terms of whether the methodologies had been applied correctly.
214 The selection of which of the two methods to use for the missile perforation calculations is
clearly laid out and is based on the validity parameters. Therefore, if the ETC-C equation
is not valid the LI Criterion is used. No examples are given where neither method is
applicable. The ETC-C method calculates the minimum thickness of concrete wall or
slab which will just be perforated. All examples given demonstrate the actual wall
thicknesses are much greater than the just perforated thickness. The LI Criterion
calculates the energy of the missile that is required to perforate a wall of a certain
thickness. Provided the missile kinetic energy is less than the energy of just perforation,
the wall is not breached by the missile. Again, the examples given have considerable
margin, i.e. the walls are much thicker than the depth of penetration.
215 I raised specific queries via TQ-EPR-1606 on how certain calculations had been carried
out. The parameters used to justify the validity of the methods in some cases were not
clearly defined. The response from EDF and AREVA (Ref. 118) satisfactorily clarified
these queries and confirmed that design criteria will be reviewed at detailed design stage
as discussed in Section 4.6.3.2.
4.6.3.4 Assessment Conclusions
216 I am satisfied that the calculations for impact damage from internal missiles sampled from
ECEIG091634 Rev B1 have been carried out correctly in accordance with Appendix 1.D
of the ETC-C. The selection of which of the two methods to use was also carried out
correctly for these examples.
217 ECEIG091634 Rev B1 refers to a separate internal missile methodology, which is
additional to the UK CD Rev E, Clause 1.4.7 bis “Internal Projectiles and Dropped
Loads”. This will be a site specific document and so I have raised AF-UKEPR-CE-83 to
require the licensee to submit and justify this in relation to the dropped load methodology
ENGSGC100483 Rev B.
218 My conclusions have been fed into the Internal Hazards assessment of GI-UKEPR-IH-04
(Ref. 119).

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4.7 ASSESSMENT OF RESPONSE TO ACTION 2

4.7.1 Introduction
219 Action 2 of GI-UKEPR-CE-02 required EDF and AREVA to update the UK Companion
Document to address the ONR comments made on AFCEN ETC-C 2010 Part 0: General.
These comments were given in ONR letter EPR70304N (Ref. 33) which had been in
respect of the UK CD Rev A (Ref. 31). The key points were:
 There is limited evidence of the independent review of the AFCEN ETC-C 2010
provided in Part 0.
 There are a large number of references to French standards, with translations not
provided.
 Loose references to “equivalent standards” and a lack of clarity of revision/version of
referenced codes and standards to be used.
 There are no references to national annexes to some standards such as EN13670.
This raises a question over the control of using French standards within the UK
construction industry.
220 The UK CD underwent four iterations until the final version submitted for GDA, Rev E
(Ref. 5) met Regulator expectations as a response to the above. The five detailed
comments made on Part 0 were consolidated in the “ETC-C Tracking Spreadsheet” the
final version of which is ENGSGC110269 Rev E (Ref. 13). This recorded EDF and
AREVA’s staged responses to each question, any further comments by ONR and
responses, thus iterating to a conclusion.
221 EDF and AREVA also produced an “Assessment File of the UK Companion Document to
AFCEN ETC-C” ENGSGC110033 Rev C (Ref. 59) which gives further background to the
justification for the revisions to each clause in the UK CD. This is because it is
inappropriate to put the full justification into a technical clause. This document was
named as a deliverable in the Resolution Plan. The mapping document requested in the
GI-UKEPR-CE-02.A2 is therefore provided by the Assessment File (Ref. 59) and by the
ETC-C Tracking Spreadsheet (Ref. 13).

4.7.2 Assessment
222 The development of the ETC-C is described in Section 3.1 of this report. The 2006
version was written by EDF. However the 2010 version has now come under the
auspices of AFCEN (French society for design, construction and in-service inspection
rules for nuclear island components). AFCEN is a body set up in France to develop
design and construction codes for nuclear power stations in light of current good practice
and developments in research and development (R&D). It was founded by the French
Alternative Energies and Atomic Energy Commission (CEA) and experts from the French
nuclear industry. AFCEN produces various design codes for use in the French nuclear
industry. AFCEN works in a similar way to international code committees for instance
technical experts sit on the AFCEN ETC-C subcommittee which may also have smaller
task groups for specific technical topics.
223 EDF and AREVA submitted the description of how the AFCEN ETC-C 2010 had been
written and independently reviewed to ensure its adequacy as a design code for nuclear
safety related, civil structures. This is given in the Assessment File (Ref. 59) as the
underlying justification to the UK CD new section “Background and Introduction”. This

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states that the ETC-C was updated from the 2006 version by taking into account the
following:
 “The assessment carried out by ASN and IRSN (French regulators) as part of the
Flamanville 3 licensing process….
 Improvements recommended by AFCEN experts….
 Operating experience feedback from the design studies and initial construction work
on Flamanville 3 and Olkiluoto 3 (Finland)….
 To conclude, another first level review of the ETC-C was performed by the experts
from EDF/AREVA taking into account an assessment carried out by the French
Safety Authorities.”
224 The UK CD describes the process of how the AFCEN ETC-C 2010 is adapted by the UK
CD and how any subsequent updates to the ETC-C are reviewed and incorporated in the
UK CD if required. Future updates to the ETC-C will be instigated by feedback from the
AFCEN experts, EPR™ design teams, constructors and operators and also any
assessments by Regulators. The AFCEN code committee for ETC-C also review
revisions of Eurocodes and international codes and standards as and when they occur.
These additional descriptions are satisfactory justification that the UK CD and the ETC-C
are independently reviewed in an equivalent manner to recognised standards.
225 The lists of codes and standards given in Tables 0.1.3-1 bis to 0.1.3-13 bis of the UK CD
Rev E has been revised to remove French standards and to include either UK or
Internationally recognised standards for use. The UK National Annexes to standards
have also been added. One comment from Step 4 was that the removal of the reference
to BS EN 1998-1 and lack of reference to good practice seismic detailing was considered
a serious shortfall. This comment has been resolved by the submission of the specific
detailing rules (see Section 4.4) and the seismic design methodology under GI-UKEPR-
CE-04 (Ref. 8). The previous omission of Eurocode 1, BS EN 1991 Part 1-7 (Ref. 20)
which deals with robustness has been corrected, and further description of how
robustness is considered has been included in the “EPR Nuclear Island Civil Engineering
Design Process Note” (Ref. 60).

4.7.3 Conclusions for Action 2

226 I consider that the responses described above satisfy Regulator expectations with
respect to GI-UKEPR-CE-02.A2. The mapping document requested in the action is
provided by the ETC-C Tracking Spreadsheet (Ref. 13) and the justification of revisions
to the UK CD are given in the Assessment File (Ref. 59), particularly where it would not
be appropriate to include the background justification in a technical clause. No
assessment findings have been raised for this action.
227 I am satisfied that GI-UKEPR-CE-02.A2 can be closed.

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4.8 ASSESSMENT OF RESPONSE TO ACTION 3

4.8.1 Introduction
228 Action 3 of GI-UKEPR-CE-02 required EDF and AREVA to update the UK Companion
Document to address the ONR comments made on AFCEN ETC-C 2010 Part 1: Design.
These comments were given in ONR letter EPR70304N (Ref. 33) which had been in
respect of the UK CD Rev A (Ref. 31). The key points were:
1) Errors in Formulas
2) Lack of Clarity/ ambiguity in text
3) Inconsistency with other sections of the code
4) Inconsistency with UK National Annex
5) Lack of guidance to designers on seismic design
6) Revisions of supporting documents unclear
7) Lack of guidance on choice of Eurocode value when no recommended value is
available
8) Justification lacking for some revised liner stress limits
229 There were a considerable number of comments made for Part 1 and its appendices.
The comments ranged from queries on fundamental technical philosophies to minor
editorial comments. As for Action A2, the detailed comments made on Part 1 were
consolidated in the “ETC-C Tracking Spreadsheet” ENGSGC110269 (Ref. 13) which
recorded EDF and AREVA’s responses to each question, any further comments by ONR
and responses, thus iterating to a conclusion.
230 Resolution of the various comments was carried out in a staged manner, following a
workshop in July 2011 and proceeded through to March 2012. Comments were
progressed separately and individual clauses of the UK CD updated on a case by case
basis as detailed in the ETC-C Tracking Spreadsheet (Ref. 13). Therefore, although
each clause was reviewed by ONR there was a need to carry out a review of the whole
document once completed in order to check that point 3 above “Inconsistency with other
sections of the code” had been resolved. This consolidated review was commissioned by
ONR with Arup and is documented in Arup report 209364-10-10 (Ref. 85)

4.8.2 Assessment
231 The final submission of the UK CD, Rev E (Ref. 5) has addressed points 1) to 8) listed in
Action A3 as detailed below.
232 For point 1), typographical errors in the AFCEN ETC-C 2010 have been corrected by the
UK CD. The corrections have been issued to the AFCEN code committee for them to
include in the next revision of the ETC-C.
233 For point 2), technical clauses which were unclear or ambiguous have been updated
satisfactorily. In addition, ONR has sought evidence that EDF and AREVA have suitable
arrangements to safeguard against misinterpretation by the designers. This has been
submitted via the “EPR Nuclear Island Civil Engineering Design Process Note” (Ref. 60)
under GI-UKEPR-CE-01 which sets out the process. Hypothesis notes are produced by
the licensee’s Design Authority for each structure and these are used as a specification to
the designer. The designer then produces a detailed design hypothesis note which
confirms the basis of design back to the Design Authority, both prior to start and upon

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completion of the detailed design. Assessment of this process is discussed in more detail
in my assessment report for GI-UKEPR-CE-01 (Ref. 7), however my conclusions are that
the arrangements proposed by EDF and AREVA for site specific design phase are
satisfactory.
234 For point 3), the comprehensive review of the complete UK CD (Ref. 85) sampled the
consistency in technical specification across the whole document. Where text did not
meet the expected standard that had already been agreed, ONR issued further
comments via the tracking sheet (Ref. 13). These comments were included in the final
Rev E of the UK CD. In addition to the assessment file ENGSGC110033 Rev C (Ref. 59)
EDF and AREVA also produced a further assessment file, ENGSGC120228 Rev A (Ref.
75) which recorded the additional revisions required from Rev D to Rev E of the UK CD.
235 For point 4) the technical adequacy of the proposed revised clauses in the UK CD were
assessed against current good practice and recognised standards such as Eurocodes
and their UK National Annexes. The assessment also reviewed the values chosen by
EDF and AREVA within the UK CD for technical parameters. The detailed review of each
comment is documented in the tracking sheet and the modification file (Refs. 13 and 14)
and so will not be repeated here. The most notable technical issues raised at the
workshop in July 2011 are shown below and the assessment of these has been already
described under Action 1 in Section 4.3 of this report.
 Justification for the load combinations in ETC-C which do not cover standard
combinations of static live + dead loads. Also the minimum imposed live load has
been removed from the AFCEN ETC-C 2010 version. (Refer to Section 4.3.2.2.)
 Justification of the concrete maximum compressive stress under bi-axial / tri-axial
behaviour accidental thermal conditions for the inner containment (Refer to Section
4.3.2.3).
 Design and provision of shear reinforcement in slabs and walls were not in
accordance with UK National Annex to Eurocode 2. (Refer to Section 4.3.2.4)
 Justification of the effective diameter of prestressing cables assumed for
reinforcement in ETC-C being different from the formulation in Eurocode 2 (refer to
Section 4.3.2.6)
 Crack control - ONR were concerned that autogenous shrinkage is ignored in
current ETC-C method for crack width assessment. Also the k2=0.5 value assumed
in the cracking assessment was considered non-conservative. (Refer to Section
4.3.2.7.)
 Justification of the consequences of concrete cracking on liner leak-tightness. (Refer
to Section 4.5.3)
 Construction Joints - ONR were concerned that design method for construction
joints proposed in AFCEN ETC-C 2010 Part 1 deviated from the Eurocode 2 method
used previously in ETC-C (2006). The new method was not seen as adequately
justified. (Refer to Section 4.4.3.)
236 For point 5), additional guidance has been submitted by EDF and AREVA for the seismic
design methodology in response to GI-UKEPR-CE-06. My assessment report for that
GDA Issue (Ref. 10) concluded that the technical documents submitted were satisfactory
for the generic phase. The UK CD Rev E now includes references to these methodology
documents and technical clauses have been updated where specification was required.

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237 For point 6) the reference list has been updated and it now includes the revisions of each
document.
238 For point 7) the final version of the UK CD now specifies values for parameters which are
required by Eurocodes. The AFCEN ETC-C 2010 is based on the French National
Annexes and so values were either not given or did not match the UK National Annexes.
The UK CD Rev E now includes parameters which agree with the UK National Annexes if
appropriate or with recognised international standard, UK standards or current good
practice.
239 For point 8) the revised liner stress limit refers to the justification of changing from the
ETC-C 2006 limits to those of ASME Section III, Division 2 (Ref. 26) in the updated
AFCEN ETC-C 2010. The assessment of this is detailed in Section 4.5.3 of this report
and my conclusion was that the ASME II limits had been justified to be appropriate for the
UK EPR™ design.

4.8.3 Conclusions for Action 3

240 I consider that the updated Part 1 of the UK CD Rev E, as supported by technical
documents submitted satisfies Regulator expectations with respect to GI-UKEPR-CE-
02.A3. The mapping document requested in the action is provided, as before, by the
ETC-C Tracking Spreadsheet (Ref. 13) and in the Assessment Files (Ref. 59 and Ref.
75). No assessment findings have been raised for this action.
241 I am satisfied that GI-UKEPR-CE-02.A3 can be closed.

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4.9 ASSESSMENT OF RESPONSE TO ACTION 4

4.9.1 Introduction
242 Action 4 of GI-UKEPR-CE-02 required EDF and AREVA to update the UK Companion
Document to address the ONR comments made on AFCEN ETC-C 2010 Part 2:
Construction. These comments were given in ONR letter EPR70767R (Ref. 34) which
had been in respect of the UK CD Rev A (Ref. 31). The key points were:
1) Insufficient information to be the basis of a clear construction specification
2) Links to French ministerial standards are of no relevance to the UK
3) Clarification of the intention to demonstrate the equivalence of French standards to
other national standards
4) Provide clarity over the approval of modifications or adaptations to the specification
5) Provide clarity over how demonstration of equivalence would be achieved
243 The ETC-C Tracking Spreadsheet ENGSGC110269 (Ref. 13) contains the comments
from Ref. 34. These comments varied from queries on the technical specification to
minor editorial comments. As before, the individual comments were resolved between
July 2011 and March 2012 on a case by case basis, the details of which are recorded in
ETC-C Tracking Spreadsheet (Ref. 13) and the Assessment Files (Refs. 59, 75 and 76).

4.9.2 Assessment
244 The final submission of the UK CD, Rev E (Ref. 5) has addressed the points within GI-
UKEPR-CE-02.A4 as described below.
245 For point 1), Part 2 of the ETC-C comprises the construction rules for the UK EPR™
required by the ETC-C detailed design. However, it forms part but not the complete
construction specification for C1 civil structures. EDF and AREVA has confirmed that the
construction specifications are site specific and will not be available until the site specific
phase and so cannot be assessed at GDA stage. This is in accordance with the agreed
scope of GDA as stated in Section 2.5 of the Step 4 Assessment Report (Ref. 2).
246 For points 2) and 3), the AFCEN ETC-C 2010 clauses that are amended by the UK CD
now reflect the codes and standards used in the UK or that are internationally recognised.
References to French standards have been removed and the equivalent standards used.
247 For point 4), the process for the approval of future modifications to the ETC-C and the UK
CD has been detailed in response to Action A2 and in the “EPR Nuclear Island Civil
Engineering Design Process Note”. Since this action, A4, is specifically for construction
clauses in the ETC-C and the construction specifications are outside the scope of GDA
any future modifications to these will be subject to Regulator scrutiny at site specific
stage.
248 For point 5), equivalence in terms of compliance to UK standards, good practice or
international standards has been provided by the updated codes and standards
referenced in the UK CD Rev E. Future construction specifications will need to justify the
quality of construction is in accordance with these standards.

4.9.3 Conclusions for Action 4

249 I am satisfied that sufficient justification has been provided for the resulting technical
clauses within Part 2 of the UK CD Rev E within the scope of GDA. The mapping of the

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revised technical clauses in the UK CD is provided by the Assessment Files (Refs. 59, 75
and 76).
250 I am therefore satisfied that GI-UKEPR-CE-02.A4 can be closed.

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5 INTERFACE OF GI-UKEPR-CE-02 WITH KEY DOCUMENTS

5.1 REVIEW OF THE PCSR

251 The EDF and AREVA resolution plan identified that resolution of GI-UKEPR-CE-02 may
require revisions to the following two sub-chapters of the March 2011 PCSR (Ref. 4).
 “Sub-chapter 3.3 – Design of Category 1 Civil Structures”.
 “Sub-chapter 3.8 – Codes and standards used in the EPR™ design”.
252 Sub-chapter 3.3 has been revised to Issue 05 (Ref. 113) and required only minimal
changes to reflect EDF and AREVA’s response to GI-UKEPR-CE-02. This is because
the detailed information is contained within the finalised supporting documents assessed
in this report. The revisions are as follows.
 The reference to the ETC-C 2006 has been replaced by the AFCEN ETC-C 2010.
 The “EPR Nuclear Island Civil Engineering Design Process Note” (Ref. 60) has
been added as a major reference.
 Update of references, particularly those which are referenced in Ref. 60 or the UK
CD which have been removed from the PCSR.
 Section 1.1 introduces the dedicated rules for C2 classified structures – this has
been assessed under GI-UKEPR-CC-01.A2 (Ref. 120).
 Minor editorial corrections.
253 Sub-chapter 3.8 has been revised to Issue 05 (Ref. 114) as follows as a result of the
resolution of GI-UKEPR-CE-02.
 The reference to the ETC-C 2006 has been replaced by the AFCEN ETC-C 2010.
 The reference to the UK CD has been updated to Rev E.
 Section 4.1 now has a clear statement that the UK CD governs the AFCEN ETC-C
2010.
 Section 4.2 now confirms the UKCD uses internationally accepted standards, UK
standards or current UK good practice rather than French standards.
 The description of the AFCEN organisation has been expanded to include the ETC-
C sub-committee.
 Minor editorial corrections.
254 Sub-chapter 13.2 Internal hazards has been revised to Issue 05 (Ref. 115) with respect to
impacts from dropped loads and internal missiles, as described in paragraph 198 of this
report. The only change required for GI-UKEPR-CE-02 was to update the reference to
the dropped load methodology to ENGSGC100483 Rev B.
255 I am satisfied that the updates made to the PCSR are sufficient to describe the safety
case for C1 civil structures which are to be designed and constructed in accordance with
the UK CD and the ETC-C. The PCSR also now includes the “EPR Nuclear Island Civil
Engineering Design Process Note” as a major underpinning document, and this signposts
the technical supporting documents.

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5.2 INTERFACE WITH OTHER GDA ISSUES

256 Resolution of this issue has required revisions to documents which are deliverables for
other GDA Issues, as follows.
 “EPR Nuclear Island Civil Engineering Design Process Note” (Ref. 60) submitted
under GI-UKEPR-CE-01.
 GI-UKEPR-CE-04 has required updates to the UK CD in respect of the technical
clauses for FE modeling of C1 structures. The relevant clauses are within Appendix
1.A Seismic Analysis and the required amendments are detailed within the
assessment files (Ref. 59 and Ref. 75).
 Seismic Analysis of Foundation Raft, ENGSDS100268 Rev B (Ref. 62) and
Methodology for Seismic Analysis of NI Buildings ENGSDS100269 Rev B (Ref. 63)
were submitted under GI-UKEPR-CE-06. These two documents are referenced
within Appendix 1.A Seismic Analysis of the UK CD. My assessment report for
closure of this issue (Ref. 10) describes the revisions required to the documents and
that both were accepted as part of the satisfactory response to the issue. Certain
clauses within the UK CD Appendix 1.A have needed updating in response to GI-
UKEPR-CE-06 and these are detailed within the assessment files (Ref. 59 and Ref.
75).
 The dropped load methodology has been assessed and found to be satisfactory
subject to three assessment findings. This has been fed into the Internal Hazards
assessment of GI-UKEPR-IH-01 (Ref. 116) and GI-UKEPR-IH-04 (Ref. 119).
 The dedicated rules for C2 structures, which are based on the ETC-C, have been
assessed under GI-UKEPR-CC-01.A2 (Ref. 120).
257 The specifics of my assessment of these deliverables with respect to each GDA issue are
given in the relevant ONR assessment report which should be read in conjunction with
this report.

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6 ASSESSMENT FINDINGS

6.1 ADDITIONAL ASSESSMENT FINDINGS

258 I conclude that the following assessment findings, also listed in Annex 1, should be taken
forwards during the site specific phase in addition to those identified in the Step 4 Civil
Engineering Assessment Report (Ref. 2).
AF-UKEPR-CE-76: The licensee shall confirm that the enhanced concrete
compressive strength used for the design of the inner containment structure
accounts for the final concrete mix design specified, and in particular the
thermal expansion coefficient for the type(s) of aggregates to be used.
Required timescale: Nuclear Island Safety-Related Concrete.
AF-UKEPR-CE-77: The licensee shall confirm that design shear strength
used for reinforced concrete structures accounts for the final type(s) of
aggregates used in the concrete mix design in accordance with the UK
National Annex to Eurocode 2, BS EN 1992-1-1.
Required timescale: First structural concrete.
AF-UKEPR-CE-78: The licensee shall provide a list of the safety critical
reinforced concrete structural elements whose behaviour under shrinkage is
dominated by end restraint. The licensee shall provide justification of the
shrinkage control methods and reinforcement provided for such elements.
Required timescale: Nuclear Island Safety-Related Concrete.
AF-UKEPR-CE-79: The licensee shall confirm that there is adequate
margin beyond design basis for safety critical non-massive structural
elements, e.g. concrete columns or steel frames, such that if plasticity
occurs in any part of those elements for the event considered, this will not
lead to sudden failure.
Required Timescale: Nuclear Island Safety-Related Concrete.
AF-UKEPR-CE-80: The licensee shall provide the final construction
specification and details for the joints within the concrete dome roof to the
inner containment, and justify that the finished structure will fulfil the nuclear
safety requirements.
Required Timescale: Install Polar Crane.
AF-UKEPR-CE-81: Where separate methods are used to check the
punching shear and the bending stresses in concrete civil structures induced
by potential dropped loads or internal missiles, the licensee shall justify that
the methods are compatible with one another.
Required timescale: Nuclear Island Safety-Related Concrete.
AF-UKEPR-CE-82: The licensee shall justify that the calculation methods
used to assess the damage to civil structures due to impact from potential
dropped loads or internal missiles, are applicable to the range of dropped
loads or missiles identified by the safety assessment for that structure.
Required timescale: Nuclear Island Safety-Related Concrete.
AF-UKEPR-CE-83: The licensee shall develop an internal missile
methodology document for the site specific design, and clarify how it

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interfaces with the dropped load methodology document. The licensee shall
also, having indentified the range of potential missile impacts for a particular
civil structure, justify that the calculation methods used to assess the impact
on civil structures from internal missiles are applicable
Required timescale: Nuclear Island Safety-Related Concrete.

6.2 IMPACTED STEP 4 ASSESSMENT FINDINGS

259 There are no impacted Step 4 assessment findings.

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7 ASSESSMENT CONCLUSIONS
260 I am satisfied that the latest version of the UK Companion Document, Rev E (Ref. 5) has
adequately addressed the ONR technical comments raised during GDA Step 4 on Parts
0, 1 and 2 of the AFCEN ETC-C 2010 design code which is to be used for the UK EPR™.
Sufficient justification has been given for the updated clauses in the UK CD and evidence
provided that they are in accordance with internationally recognised codes and standards
and UK current good practice. Omissions noted by ONR have also been corrected.
261 Section 4.3 presents my assessment of the supporting technical documents submitted as
responses to the nine technical areas listed in GI-UKEPR-CE-02.A1. Sections 4.4 to 4.6
present my assessment of the three methodologies also required by A1: detailing
provisions, pool liner design and dropped loads analysis. These documents have been
assessed and I consider that they satisfy Regulator expectations with respect to the
generic information required for GI-UKEPR-CE-02.A1. The documents also clarify what
design information is included in the generic submission and what will be developed
further during the site specific phase.
262 I am satisfied that GI-UKEPR-CE-02.A1 can be closed.
263 Sections 4.7, 4.8 and 4.9 present my assessment of the updated clauses within the UK
CD Rev E which have been modified in response to GI-UKEPR-CE-02.A2, A3 and A4.
The technical detail to these updates has been documented by EDF and AREVA in
documents called Assessment Files. These describe the rationale for any updates to
clauses within the UK CD, and also record additional justification of clauses which were
questioned by ONR but have subsequently been agreed as adequate. The relevant
Assessment Files are Refs. 59, 75 and 76.
264 I am satisfied that actions GI-UKEPR-CE-02.A2, A3 and A4 can be closed.
265 Resolution of GI-UKEPR-CE-02 has also benefitted from the introduction of the “EPR
Nuclear Island Civil Engineering Design Process Note” (Ref. 60) submitted under GI-
UKEPR-CE-01. This document is an overarching description of the civil engineering
design process and confirms the hierarchy of design documentation, including the UK CD
and the AFCEN ETC-C 2010. My assessment of Ref. 60 is given in ONR report ONR-
GDA-AR-12-006 (Ref. 7).
266 I have raised eight assessment findings (AF-UKEPR-CE-76 to AF-UKEPR-CE-83) to
help ensure compliance with the outcomes from GI-UKEPR-CE-02. I also note that the
assessment of the complete construction specifications for civil structures is outside of
the GDA scope and this will be subject to regulatory scrutiny at site specific stage.
267 Relevant sub-chapters 3.3 and 3.8 of the March 2011 PCSR have been revised such that
I am satisfied the safety case is based on the current submission.
268 I therefore conclude that GI-UKEPR-CE-02 can be closed.

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8 REFERENCES
Ref. Document
1 GDA Issue GI-UKEPR-CE-02 Revision 1. Use of ETC-C for the Design and Construction of
the UK EPR™. July 2011. TRIM Ref. 2011/385289 (TRIM folder 5.1.3.6348.)
2 Step 4 Civil Engineering and External Hazards Assessment of the EDF and AREVA UK
EPR™ Reactor. ONR Assessment Report ONR-GDA-AR-11-018 Rev 0, December 2011.
TRIM Ref. 2010/581513. (TRIM folder 4.4.1.1827.).
3 Resolution Plan for GI-UKEPR-CE-02. EDF and AREVA. Rev 0, 29/06/2011.
TRIM Ref. 2011/345898.
4 AFCEN ETC-C 2010 Edition: ETC-C EPR Technical Code for Civil Works. AFCEN.
23 December 2010. TRIM Ref. 2011/430452.
5 UK Companion Document to AFCEN ETC-C, ENGSGC110015 Rev E, EDF and AREVA,
Sept 2012. TRIM Ref. 2012/350151.
6 UK EPR™ GDA Step 4 Consolidated Pre-construction Safety Report – March 2011. EDF
and AREVA. Detailed in EDF and AREVA letter UN REG EPR00997N. 18 November 2011.
TRIM Ref. 2011/552663.
7 GDA Close-out for the EDF and AREVA UK EPR™ Reactor – GDA Issue GI-UKEPR-CE-
01 Revision 1 – Hypothesis and Methodology Notes for Class 1 Structures, ONR
Assessment Report ONR-GDA-AR-12-006 Rev. 0. January 2013. TRIM Ref. 2012/6.

8 GDA Close-out for the EDF and AREVA UK EPR™ Reactor – GDA Issue GI-UKEPR-CE-
03 Revision 1 - Beyond Design Basis Performance of the Inner Containment and GDA
Issue UKEPR-CE-04 Revision 1 - Analysis of the Containment. ONR assessment report
ONR-GDA-AR-12-003, Rev 0, January 2013. TRIM Ref: 2012/3.
9 GDA Close-out for the EDF and AREVA UK EPR™ Reactor – GDA Issue GI-UKEPR-CE-
05 Revision 1 – Reliability of the ETC-C, ONR Assessment Report ONR-GDA-AR-12-001
Rev. 1, May 2012. TRIM Ref. 2012/214232.
10 GDA Close-out for the EDF and AREVA UK EPR™ Reactor – GDA Issue GI-UKEPR-CE-
06 Revision 1 – Seismic Analysis Methodology for the Design of the UK EPR™, ONR
Assessment Report ONR-GDA-AR-12-002 Rev. 0, December 2012. TRIM Ref. 2012/2.
11 ONR HOW2 Business Management System. Document PI/FWD “Permissioning - Purpose
and Scope of Permissioning”, Issue 3.
12 Assessment Plan for Civil Engineering and External Hazards, Closure of GDA for the
EPR™, ONR Assessment Plan ONR-GDA-AP-11-001, Rev 0, Nov 2011. TRIM Ref.
2011/650014
13 ETC-C Tracking Sheet for resolution of GI-UKEPR-CE-02, ENGSGC110269.xls, EDF and
AREVA, Rev E ONR 107, 25 June 2012. TRIM Ref. 2012/257921.
14 Additional Modifications to ENGSGC110015.doc, ENGSGC110269.doc Appendix 1, EDF
and AREVA, Rev E, April 2012. TRIM Ref. 2012/455130.
15 Safety Assessment Principles for Nuclear Facilities. 2006 Edition Rev 1. HSE. January
2008. www.hse.gov.uk/nuclear/SAP/SAP2006.pdf.

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16 ONR Technical Assessment Guides
External Hazards. T/AST/013 Issue 4. July 2011.
Structural Integrity Civil Engineering Aspects. T/AST/017 Issue 2. HSE. March 2005
ONR guidance on the demonstration of ALARP (as low as reasonably practicable),
T/AST/005, Issue 4 Rev 1, Jan 2009.
Fundamental Principles, T/AST/004, Issue 3, March 2010
www.hse.gov.uk/nuclear/operational/tech_asst_guides/index.htm.
17 Safety of Nuclear Power Plants: Design. Safety Requirements. International Atomic Energy
Agency (IAEA). Safety Standards Series No. NS-R-1. IAEA. Vienna. 2000. www.iaea.org.
18 Western European Nuclear Regulators’ Association. Reactor Harmonization Group.
WENRA Reactor Reference Safety Levels. WENRA. January 2008. www.wenra.org.
19 BS EN 1990:2002. Basis of Structural Design. British Standards Institution, CEN Comite
European de Normalisation. July 2002,
Amendment 1:2005, 15 December 2004.
UK National Annex to BS EN 1990:2002
20 BS EN 1991 – Eurocode 1 – Actions on Structures, British Standards Institution, CEN
Comite European de Normalisation.
 BS EN 1991-1-1:2002. Part 1-1: General actions – Densities, self weight, imposed
loads for buildings. 2002 and AC:2009.
 BS EN 1991-1-7:2006. Part 1-7: General actions - Accidental actions. 2006 and AC
2010

UK National Annex to Eurocode 1: Actions on Structures. General Actions

 NA to BS EN 1991-1-1. – Densities, self weight, imposed loads for buildings. 2005.
 NA to BS EN 1991-1-7:2006 – Accidental Actions
21 BS EN 1992, Eurocode 2: Design of concrete structures. British Standards Institution, CEN
Comite European de Normalisation.
 BS EN 1992-1-1: 2004. Part 1-1: General rules and rules for buildings. 23/12/2004.
 BS EN 1992-1-2: 2004. Part 1.2: Structural fire design. 09/02/2005.
 BS EN 1992-2: 2005. Part 2: Concrete bridges. Design and detailing rules. 02/12/2005.
 BS EN 1992-3: 2006. Part 3: Liquid retaining and containing structures. 31/07/2006.

UK National Annexes to Eurocode 2: Design of concrete structures.

 NA to BS EN 1992-1-1:2004. Part 1-1: General rules and rules for buildings.
08/12/2005.
 NA to BS EN 1992-1-2: 2004. Part 1.2: Structural fire design 08/12/2005
 NA to BS EN 1992-2: 2005. Part 2: Concrete bridges. Design and detailing rules.
31/12/2007
 NA to BS EN 1992-3: 2006. Part 3: Liquid retaining and containing structures.
31/10/2007
22 BS EN 1993. Eurocode 3: Design of steel structures.
 BS EN 1993-1-1:2005. general rules and rules for buildings.
 BS EN 1993-2:2006, Design of Steel Structures. Steel bridges. 30/11/2006.
 BS EN 1993-4-2:2007 Design of Steel Structures. Tanks. 31/05/2007

UK National Annexes to Eurocode 3: Design of steel structures.

NA to BS EN 1993-1-1:2005. general rules and rules for buildings

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23 BS EN 1998, Eurocode 8, Design of Structures for Earthquake Resistance.
 BS EN 1998-1:2004. General Rules, seismic actions and rules for buildings.
08/04/2005.
 UK National Annexe to BS EN 1998-1:2004. General Rules, seismic actions and rules
for buildings. 29/08/2008
24 Code Requirements for Nuclear Safety Related Concrete Structures and Commentary.
ACI 349-06. American Concrete Institute. 1st September 2007.
25 Building Code Requirements for Structural Concrete and Commentary. ACI 318-11.
American Concrete Institute. 2011.
ISBN: 9780870317446.
26 Section III, Division 2, ASME Boiler and Pressure Vessel Code. Code for Concrete
Containments – Rules for Construction of Nuclear Facility Components. ACI 359M-07
ASME. 2007
27 Fastenings to Concrete and Masonry Structures, CEB Bulletin No 216, 1994. ISBN 978-0-
7277-1937-9
The International Federation for Structural Concrete (FIB - fédération internationale du
béton), www.fib-international.org. Formerly the Euro-International Concrete Committee
(CEB - Comité Euro-International du Béton).
28 Early-age thermal crack control in concrete, CIRIA Guide C660. Construction Industry
Research and Information Association, London. February 2007. ISBN: 978-0-86017-660-2
29 Design of fastenings for use in concrete. Eurocode 2 Part 4 Document in Development DD
CEN/TS 1992-4:2009, BSi, 30 June 2009, ISBN 978 0 580 62635 7
30 ETC-C EPR Technical Code for Civil Works. Rev B, 2006. EDF.
TRIM Ref. 1710/404165.

31 UK Companion Document to AFCEN ETC-C – Part 1. ENGSGC110015 Rev A. 11

February 2011. EDF. TRIM Ref. 2011/128959.
32 Various Submissions on ETC-C. Letter from ND to UK EPR™ Project Front Office. Unique
Number EPR70291R. 3 February 2011.
TRIM Ref. 2011/70303.
33 AFCEN ETC-C April 2010. Letter from ND to UK EPR™ Project Front Office with
comments on Part 0 and Part 1 and provisional comments on Part 2 and Part 3. Unique
Number EPR70304N. 19 April 2011. TRIM Ref. 2011/235790.
34 AFCEN ETC-C Part 2. Letter from ONR to UK EPR™ Project Front Office. Unique Number
EPR70367R. 07 October 2011. TRIM Ref. 2011/514252.
35 Determination of the α cc coefficient used in the formula for the design value of the
compressive strength in Eurocode 2. ENGSGC100384 Rev B. EDF.
TRIM Ref. 2011/306266.

36 GDA – Presentation and justification of ψi factors of ETC-C for variable actions in

accidental and non-accidental situations. ENGSGC100394 Rev B. EDF. 2 March 2011.
TRIM Ref. 2011/132210.
37 Justification of the concrete maximum compressive stress under bi axial/triaxial behaviour
(accidental thermal conditions for the inner containment). ENGSGC100415 Rev B. EDF. 17
March 2011. TRIM Ref. 2011/159534.

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38 EPR UK – Shear design proposal. ENGSGC100410 Rev C. EDF, March 2011, TRIM Ref.
2012/81186 (Issued under EPR00824N. 8 March 2011. TRIM Ref. 2011/139617.)
39 Steel and concrete partial safety factors for EPR™ fastening systems. ENGSGC100395
Rev B. EDF. 11 November 2010. TRIM Ref. 2011/237385.
40 UK EPR™ – GDA – Prestressing tendons participation in reinforced concrete calculations
for the inner containment. ENGSGC 100416 Rev B. EDF. 18 February 2011.
TRIM Ref. 2011/128599.
41 UK EPR™ – GDA – Methodology for consideration of shrinkage for EPR™ concrete
structures. ENGSGC100426 Rev B. EDF. 31 January 2011. TRIM Ref. 2011/128924.
42 UK EPR™ – GDA – Verification of crack width for EPR™ concrete structures for durability
requirement. ENGSGC100428 Rev B. EDF. 31 January 2011.
TRIM Ref. 2011/128922.
43 Global approach about methodology for consideration of shrinkage and crack limitation.
ENGSGC110025 Rev A, EDF, February 2011. TRIM Ref. 2011/128920.
44 Justification of the partial factor for prestressing actions γ P . ENGSGC100402 Rev A. EDF.
14 December 2010. TRIM Ref. 2011/85932.
45 EPR™ Safety Category 1 (C1) Structures – Good Practice Detailing Rules for Reinforced
Concrete and Steel Structures. ENGSGC110157 Rev A EDF, TRIM Ref 2011/376079

46 Pool Liner Design Requirements and Methodology, ENGSGC110243 Rev A. EDF August
2011. TRIM Ref 2011/415254

47 Methods with regard to the risk of dropped loads for EPR™ UK for concrete structures,
ENGSGC100483 Rev A, EDF and AREVA. April 2011. TRIM Ref. 2011/326141

48 UK Companion Document to AFCEN ETC-C – Part 1. ENGSGC110015 Rev B. April 2011.

EDF. TRIM Ref. 2011/227961.
49 Assessment File of the UK Companion Document to AFCEN ETC-C, ENGSGC110033,
Rev B, April 2011, EDF SEPTEN. TRIM Ref. 2011/227964.
50 EPR Nuclear Island Civil Engineering Design Process, ECEIG111110 Rev A, EDF and
AREVA, August 2011, TRIM Ref. 2011/425958
51 ETC-C Part 2.10 – Mapping of Changes from ETC-C Revision B to AFCEN ETC-C 2010 ,
ETDOIG110305, Rev A, EDF, June 2011. TRIM Ref. 2011/319054
52 ETC-C Part 2: Construction Update – Mapping of Changes from ETC-C Revision B to
AFCEN 2010 ETC-C (Sections 2.2 to 2.5, 2.11, and 2.12) EDTGC110381 Rev A, EDF,
June 2011, TRIM Ref. 2011/321789
53 GDA – Presentation and justification of ψi factors of ETC-C for variable actions in
accidental and non-accidental situations. ENGSGC100394 Rev C. EDF. Aug 2011.
TRIM Ref. 2011/450247.
54 EP™R UK – Shear design proposal. ENGSGC100410 Rev D. EDF, February 2012, TRIM
Ref. 2012/81186
55 EPR™ UK – GDA – Prestressing tendons participation in reinforced concrete calculations
for the inner containment. ENGSGC100416 Rev C. EDF. September 2011. TRIM Ref.
2011/493146

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56 EPR™ Safety Category 1 (C1) Structures – Good Practice Detailing Rules for Reinforced
Concrete and Steel Structures. ENGSGC110157 Rev B. EDF. TRIM Ref. 2011/620177
57 Pool Liner Design Requirements and Methodology. ENGSGC110243 Rev B. EDF.
TRIM Ref. 2012/112052
58 Methods with regard to the risk of dropped loads for EPR™ UK for civil works structures,
ENGSGC100483 Rev B, EDF and AREVA. March 2012. TRIM Ref. 2012/116384.
59 Assessment File of the UK Companion Document to AFCEN ETC-C, ENGSGC110033
Rev C, EDF, May 2012. TRIM Ref. 2012/227355.
60 EPR Nuclear Island Civil Engineering Design Process, ECEIG111110 Rev C, EDF and
AREVA, September 2012, TRIM Ref. 2012/422394.

61 Not Used.
62 UK EPR™ - Seismic Analysis of Foundation Raft. ENGSDS100268 Rev B. EDF and
AREVA. April 2012. TRIM Ref. 2012/154518.

63 UK EPR™ - Methodology for Seismic Analysis of NI Buildings. ENGSDS100269 Rev B.

EDF and AREVA. May 2012. TRIM Ref. 2012/184476.

64 GDA Issue GI-UKEPR-CE-01 Revision 1. Hypothesis and Methodology Notes for Class 1
Structures. July 2011. Office for Nuclear Regulation, TRIM Ref. 2011/385288
65 GDA Issue GI-UKEPR-CE-03 Revision 1. Beyond Design Basis Behaviour Of The
Containment. July 2011. Office for Nuclear Regulation TRIM Ref. 2011/385290
66 GDA Issue GI-UKEPR-CE-04 Revision 1. Containment Analysis, July 2011. Office for
Nuclear Regulation. TRIM Ref. 2011/385291
67 GDA Issue GI-UKEPR-CE-05 Revision 1. Reliability Of The ETC-C, July 2011. Office for
Nuclear Regulation, TRIM Ref. 2011/385292
68 GDA Issue GI-UKEPR-CE-06 Revision 1. Seismic Analysis Methodology. July 2011. Office
for Nuclear Regulation. TRIM Ref. 2011/385293
69 GDA Issue GI-UKEPR-IH-01 Revision 2. Substantiation And Analysis Of The
Consequences Of Dropped Loads And Impact From Lifting Equipment Included Within The
EPR™ Design ONR, July 2011. TRIM Ref. 2011/385308 (TRIM folder 5.1.3.6348.)
70 GDA Issue GI-UKEPR-IH-04 Revision 2. Consequences of Missile Generation Arising From
Failure of RCC-M Components, ONR July 2011. TRIM Ref. 2011/385311
71 GDA Issue GI-UKEPR-CC-01.A2, Classification of structures systems and components,
ONR July 2011. TRIM Ref. 2011/385286
72 Classification of Structures Systems and Components, NEPS-F DC 557 Rev D Fin_2,
AREVA, 10 October 2012. TRIM Ref. 2012/595982.
73 UK Companion Document to AFCEN ETC-C, ENGSGC110015 Rev D Preliminary, EDF
and AREVA, March 2012. TRIM Ref. 2012/103915.
74 UK Companion Document to AFCEN ETC-C, ENGSGC110015 Rev D, EDF and AREVA,
May 2012. TRIM Ref. 2012/184807.

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75 Assessment File of Revision E of UK Companion Document to the AFCEN ETC-C 2010,
ENGSGC120228 Rev A. EDF, September 2012. TRIM Ref. 2012/350152.
76 Assessment File of the UK Companion Document to AFCEN ETC-C, (Section 2.2 to 2.5 of
ENGSGC110015 D), EDTGC120392 Rev A, EDF CEIDRE, May 2012. TRIM Ref.
2012/227353.
77 Post Step 4 Review of the GDA Issue on ETC-C for the UK EPR™ - Review of revised
supporting documents.
Report 209364-10-01 Issue, Nov 2011, Ove Arup & Partners. TRIM Ref. 2012/288747.
78 Review of Document ENGSGC110222 Rev A, “Justification of the AFCEN ETC-C
Construction Joint Design Method” Report 209364-10-02 Issue, Nov 2011, Ove Arup &
Partners. TRIM Ref. 2012/288756
79 Post Step 4 Review of the GDA Issue on ETC-C for the UK EPR™ - Control of cracking
due to Thermal and Shrinkage Effects, Report 209364-10-03 Issue, Nov 2011, Ove Arup &
Partners. TRIM Ref. 2012/288761
80 Review of EDF/AREVA Document ENGS110046 Rev A - Presentation and justification of
the consequences of concrete cracking on liner leaktightness. Report 209364-10-04 Issue,
Nov 2011, Ove Arup & Partners. TRIM Ref. 2012/288771
81 Post Step 4 Review of the GDA Issue on ETC-C for the UK EPR™ - Review of document
ENGSGC110157 Rev A, Report 209364-10-05, Issue, Nov 2011, Ove Arup & Partners.
TRIM Ref. 2012/288777
82 Review of Document ENGSGC110345 Rev A, “Justification of ETC-C Shrinkage rules”
Report 209364-10-06 Issue, April 2012, Ove Arup & Partners. TRIM Ref. 2012/288845
83 Review of Document EPR01031N, “GDA Issue GI-UKEPR-CE02: Revised proposal for out-
of-plane shear reinforcement in structures designed according to AFCEN ETC-C 2010 (UK
Companion Document)” Report 209364-10-07 Issue, April 2012, Ove Arup & Partners.
TRIM Ref. 2012/288849
84 Review of document ENGSGC100410 Rev D - EPR-UK shear design proposal
Report 209364-10-08 Issue, June 2012, Ove Arup & Partners. TRIM Ref. 2012/288853
85 Use of ETC–C in the design of nuclear structure. Review of ETC–C 2010 AFCEN and UK
Companion Document Rev D PREL, Report 209364-10-10 Issue, June 2012, Ove Arup &
Partners. TRIM Ref. 2012/288859
86 Review of ENGSGC110243 Rev A, “Pool Liner Design Requirements and Methodology”,
Report 209364-10-11 Issue, September 2011, Ove Arup & Partners.
TRIM Ref. 2011/415254.

87 GDA Issue GI-UKEPR-CE02: Revised proposal for out-of-plane shear reinforcement in

structures designed according to AFCEN ETC-C 2010. EDF and AREVA Letter
EPR01031N, December 2011, TRIM Ref 2011/635109.
88 Comments on EDF and AREVA Letter EPR01031N, “GDA Issue GI-UKEPR-CE02:
Revised proposal for out-of-plane shear reinforcement in structures designed according to
AFCEN ETC-C 2010. Email from ONR to EDF, TRIM Ref 2012/0059085.
89 New proposal for out of plane shear reinforcement, ENGSGC110375 Rev B, EDF, March
2012. TRIM Ref. 2012/59106.

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90 Comments on ENGSGC110375 B Out of Plane Shear Reinforcement, Email from ONR to
EDF. Jan 2012. TRIM Ref. 2012/0059104.
91 PD6687-1:2010. Background paper to the National Annexes to BS EN 1992-1 and BS EN
1992-3. BSi 13 December 2010. ISBN: 978 0 580 58685 9.
92 Justification of the AFCEN ETC-C Construction Joint Design Method. ENGSGC110222 Rev
A, EDF, September 2011. TRIM Ref. 2011/476860.
93 EDF and AREVA UK EPR™ - Schedule of Technical Queries Raised during GDA Step 1 to
Step 4. HSE-ND. TRIM Ref. 1710/600726.
94 GDA Issue CE-02- ETC-C, ONR Letter EPR70370N, dated 12/10/2011. TRIM Ref.
2011/524780 and 2011/524830
95 Justification of ETC-C Shrinkage rules, ENGSGC110345 Rev A. EDF January 2012.
Submitted under cover of letter EPR01056N. TRIM Ref 2012/9844.
96 Email from AREVA to ONR. ENGSGC110157 Rev B Prel Good Practice Guide for
Detailing Provisions November 2011 TRIM Ref 2012/0058842
97 Seismic rules for EPR™ Civil Works - Justification of ETC-C seismic design rules. Report
by Philipe Bisch in support of ENGSGC110157 Rev B Prel. Sent via Email from AREVA to
ONR, TRIM Ref 2012/0058854

98 Detailing Rules for C1 Steel Structures. Letter from UK EPR™ Project Front Office to ONR,
Unique Number EPR01108N. 8th March 2012. TRIM Ref. 2012/107410
99 Structural Steel Design – Expert Opinion. 8 March 2012, Authors Pierre-Olivier Martin and
Patrick Le Chaffotec, CTICM (Centre Technique Industriel de la Construction Metallique )
TRIM Ref. 2012/107430
100 GDA Issue GI-UKEPR-CE02 TATS Action #47.1: Constructions Joints (CJs). Letter from
UK EPR™ Project Front Office to ONR Unique Number EPR01060N, 19/01/12.
TRIM Ref. 2012/32989.
101 UK EPR™ – GDA – Presentation and Justification of the Consequences of Concrete
Cracking on Liner Leak-tightness, ENGSC110046 Rev A, EDF, September 2011. TRIM
Ref. 2011/497144.
102 ONR comments on ENGSGC110243 Rev A. Letter from ONR to UK EPR™ Project Front
Office. Unique Number EPR70366R. 5th October 2011.
TRIM Ref. 2011/510996 (letter) and 2011/511017 (comments)
103 GDA of EPR™ Pools and Liners methodology report, ENGSGC110243 Rev B Prel, EDF,
January 2012. Sent via email from AREVA to ONR. TRIM Ref 2012/057187.
104 GDA of EPR™ TA comments on ENGSGC 110243 Rev B Prel Pools and Tanks Liner
Design Requirements, Email from ONR to EDF, Feb 2012, TRIM Ref 2012/0057162

105 GDA Issue GI-UKEPR-CE02.A2: Methodology and Justification Reports for Design of Pool
and Containment Liners. Letter from UK EPR™ Project Front Office to ONR. Unique
Number EPR01114N. 12th March 2012. TRIM Ref. 2012/111987
106 UK EPR™ – GDA – Presentation and Justification of the Consequences of Concrete
Cracking on Liner Leak-tightness, ENGSC110046 Rev B, EDF, February 2012. TRIM Ref.
2012/112026

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107 ONR comments on ENGSGC110046 Rev A. Email from ONR to EDF, 18 November 2011
TRIM Ref 2012/350324.
108 Step 4 Internal Hazards Assessment of the EDF and AREVA UK EPR™ Reactor. ONR
Assessment Report ONR-GDA-AR-11-017 Rev 0, December 2011. TRIM Ref.
2010581514. (TRIM folder 4.4.1.1827.).
109 GDA - UK EPR™ Review of GDA Issue on Dropped Loads report ENGSGC100483 Rev A,
2120812-R-07 Issue 2, ABS Consulting Ltd, March 2012. TRIM 2012/301272.
110 ONR Comments on ENGSGC100483 Rev.A, ONR, 26 August 2011, TRIM Ref.
2011/0448467.
111 Letter EPR01098N, GDA Issue GI-UKEPR-IH-01.A2: Approach taken to treat Dropped
Loads on Civil Structures, EDF and AREVA, 13 March 2012, TRIM Ref. 2012/116374.
112 R3 Impact Assessment Procedure, Magnox Electric plc British Energy Generation Ltd 2003.
113 UK EPR™ PCSR Sub-chapter 3.3 – Design of Safety Classified Civil Structure. EDF and
AREVA, UKEPR-0002-035 Issue 05, October 2012. TRIM Ref. 2012/422397.
114 UK EPR™ PCSR Sub-chapter 3.8 - Codes and standards used in the EPR™ design. EDF
and AREVA. UKEPR-0002-038 Issue 05, September 2012. TRIM Ref. 2012/226767
115 UK EPR™ PCSR Sub-Chapter 13.2 – Internal Hazards Protection. EDF and AREVA.
UKEPR-0002-132 Issue 05, 31 October 2012. TRIM Ref. 2012/425734
116 GDA Close-out for the EDF and AREVA UK EPR™ Reactor, GDA Issue GI-UKEPR-IH-01
Rev 2 - Internal Hazards Assessment Report ONR-GDA-AR-12-016, Rev 0, December
2012, TRIM Ref. 2011/0016.

117 EPR™ – Internal missiles – Risk assessment report on building structure and layout,
ECEIG091634 Rev B1, EDF, April 2011. TRIM Ref. 2011/324014. Received via letter
EPR00875N 15 June 2011.
118 TQ-EPR-1606 Full Response, EDF and AREVA, 31 May 2012. TRIM Ref 2012/225343.
119 GDA Close-out for the EDF and AREVA UK EPR™ Reactor, GDA Issue GI-UKEPR-IH-04
Rev 2 - Internal Hazards Assessment Report ONR-GDA-AR-12-015, Rev 0, December
2012, TRIM Ref. 2011/0015.
120 ONR Assessment Note UKEPR™ - Civil Engineering Review of GI-UKEPR-CC-01.A2,
Classification of Civil Structures, ONR, to be published. TRIM Ref. 2012/455299

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Table 1: Relevant SAPs Considered for Close-out of GI-UKEPR-CE-02

SAP No. SAP Title Description

ECS.3 Engineering principles: Safety classification and standards Structures, systems and components that are important to
Standards safety should be designed, manufactured, constructed,
installed, commissioned, quality assured, maintained, tested
and inspected to the appropriate standards.

ECS.4 Engineering principles: Safety classification and standards For structures, systems and components that are important to
Codes and standards safety, for which there are no appropriate established codes or
standards, an approach derived from existing codes or
standards for similar equipment, in applications with similar
safety significance, may be applied.

ECS.5 Safety classification and standards In the absence of applicable or relevant codes and standards,
Use of experience, tests or analysis the results of experience, tests, analysis, or a combination
thereof, should be applied to demonstrate that the item will
perform its safety function(s) to a level commensurate with its
classification.

ECE.6 Engineering principles: civil engineering For safety-related structures, load development and a schedule
Design of load combinations within the design basis together with their
frequency should be used as the basis for the design against
Loadings
operating, testing and fault conditions.

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Table 1: Relevant SAPs Considered for Close-out of GI-UKEPR-CE-02

SAP No. SAP Title Description

EHA.14 Engineering principles: External and internal hazards Sources that could give rise to fire, explosion, missiles, toxic
Fire, explosion, missiles, toxic gases etc – sources of harm gas release, collapsing or falling loads, pipe failure effects, or
internal and external flooding should be identified, specified
quantitatively and their potential as a source of harm to the
nuclear facility assessed.

ECE.12 Engineering principles: civil engineering Structural analysis or model testing should be carried out to
support the design and should demonstrate that the structure
Structural analysis and model testing
can fulfil its safety functional requirements over the lifetime of
the facility.

ECE.13 Engineering principles: civil engineering The data used in any analysis should be such that the analysis
structural analysis and model testing is demonstrably conservative.
Use of data
ECE.14 Engineering principles: civil engineering Studies should be carried out to determine the sensitivity of
structural analysis and model testing analytical results to the assumptions made, the data used, and
Sensitivity studies the methods of calculation.

ECE.15 Engineering principles: civil engineering: Where analyses have been carried out on civil structures to
structural analysis and model testing derive static and dynamic structural loadings for the design, the
Validation of methods methods used should be adequately validated.

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Annex 1

GDA Assessment Findings Arising from GDA Close-out for GI-UKEPR-CE-02 Rev 1

MILESTONE
Finding No. Assessment Finding
(by which this item should be addressed)

AF-UKEPR-CE-76 The licensee shall confirm that the enhanced concrete compressive strength Nuclear Island Safety-Related Concrete
used for the design of the inner containment structure accounts for the final
concrete mix design specified, and in particular the thermal expansion
coefficient for the type(s) of aggregates to be used.
AF-UKEPR-CE-77 The licensee shall confirm that design shear strength used for reinforced First Structural Concrete
concrete structures accounts for the final type(s) of aggregates used in the
concrete mix design in accordance with the UK National Annex to Eurocode
2, BS EN 1992-1-1.

AF-UKEPR-CE-78 The licensee shall provide a list of the safety critical reinforced concrete Nuclear Island Safety-Related Concrete
structural elements whose behaviour under shrinkage is dominated by end
restraint. The licensee shall provide justification of the shrinkage control
methods and reinforcement provided for such elements.

AF-UKEPR-CE-79 The licensee shall confirm that there is adequate margin beyond design Nuclear Island Safety-Related Concrete
basis for safety critical non-massive structural elements, e.g. concrete
columns or steel frames, such that if plasticity occurs in any part of those
elements for the event considered, this will not lead to sudden failure.

AF-UKEPR-CE-80 The licensee shall provide the final construction specification and details for Install Polar Crane
the joints within the concrete dome roof to the inner containment, and justify
that the finished structure will fulfil the nuclear safety requirements.

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An agency of HSE

Annex 1

GDA Assessment Findings Arising from GDA Close-out for GI-UKEPR-CE-02 Rev 1

MILESTONE
Finding No. Assessment Finding
(by which this item should be addressed)

AF-UKEPR-CE-81 Where separate methods are used to check the punching shear and the Nuclear Island Safety-Related Concrete
bending stresses in concrete civil structures induced by potential dropped
loads or internal missiles, the licensee shall justify that the methods are
compatible with one another.

AF-UKEPR-CE-82 The licensee shall justify that the calculation methods used to assess the Nuclear Island Safety-Related Concrete
damage to civil structures due to impact from potential dropped loads or
internal missiles, are applicable to the range of dropped loads or missiles
identified by the safety assessment for that structure.

AF-UKEPR-CE-83 The licensee shall develop an internal missile methodology document for the Nuclear Island Safety-Related Concrete
site specific design, and clarify how it interfaces with the dropped load
methodology document. The licensee shall also, having indentified the
range of potential missile impacts for a particular civil structure, justify that
the calculation methods used to assess the impact on civil structures from
internal missiles are applicable.
…
Note: It is the responsibility of the licensees / operators to have adequate arrangements to address the assessment findings. Future licensees / operators can adopt alternative means to those indicated in
the findings which give an equivalent level of safety.
For assessment findings relevant to the operational phase of the reactor, the licensees / operators must adequately address the findings during the operational phase. For other assessment findings, it is the
regulators' expectation that the findings are adequately addressed no later than the milestones indicated above.

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Annex 2
GDA ISSUE
USE OF ETC-C FOR THE DESIGN AND CONSTRUCTION OF THE UK EPR™
GI-UKEPR-CE-02 REVISION 1

Technical Area CIVIL ENGINEERING

Related Technical Areas None

GDA Issue GI-UKEPR-CE-02 GDA Issue Action GI-UKEPR-CE-02.A1

Reference Reference

GDA Issue There is not yet sufficient justification of the AFCEN ETC-C 2010 version and UK
Companion Document to confirm these can be used for the design, construction and
testing of the UK EPR™ civil works structures.

GDA Issue Support assessment within the following areas by providing adequate responses to any
Action questions arising from assessment by ONR of documents submitted during GDA Step 4
but not reviewed in detail at that time:
 a cc Coefficient
 Load Combination Factors
 Biaxial Stress Limits
 Shear
 Fastenings
 Pre-stressing Participation
 Shrinkage
 Crack Width Control
 Pre-stressing Partial Factor

Provide additional supporting documents on the following areas

 Detailing provisions
 Pool Liner Design
 Drop Load Analysis

With agreement from the Regulator this action may be completed by alternative means.

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Annex 2
EDF AND AREVA UK EPR™ GENERIC DESIGN ASSESSMENT
GDA ISSUE
USE OF ETC-C FOR THE DESIGN AND CONSTRUCTION OF THE UK EPR™
GI-UKEPR-CE-02 REVISION 1

Technical Area CIVIL ENGINEERING

Related Technical Areas None

GDA Issue GI-UKEPR-CE-02 GDA Issue Action GI-UKEPR-CE-02.A2

Reference Reference

GDA Issue Provide a revision of the UK companion document which addresses the
Action observations raised on AFCEN ETC-C Part 0 as a result of our assessment, the
key points being:
 Lack of independent review of the code.
 References to French standards, with translations not provided
 Loose references to “equivalent standards”
 There are no references to national annexes to some standards such as
EN13670
In addition, please provide a mapping document (i.e. updated ETC-C assessment
file) which identifies how these points have been dealt with.

With agreement from the Regulator this action may be completed by alternative
means.

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An agency of HSE

Annex 2

GDA ISSUE
USE OF ETC-C FOR THE DESIGN AND CONSTRUCTION OF THE UK EPR™
GI-UKEPR-CE-02 REVISION 1

Technical Area CIVIL ENGINEERING

Related Technical Areas None

GDA Issue GI-UKEPR-CE-02 GDA Issue Action GI-UKEPR-CE-02.A3

Reference Reference

GDA Issue Provide a revision of the UK companion document which addresses the
Action observations raised on AFCEN ETC-C Part 1 as a result of our assessment, the
key points being:
 Errors in Formulas
 Lack of Clarity/ ambiguity in text
 Inconsistency with other sections of the code
 Inconsistency with UK National Annex
 Lack of guidance to designers on seismic design
 Revisions of supporting documents unclear
 Lack of guidance on choice of Eurocode value when no recommended
value is available
 Justification lacking for some revised liner stress limits
In addition, please provide a mapping document (i.e. updated ETC-C assessment
file) which identifies how these points have been dealt with.
With agreement from the Regulator this action may be completed by alternative
means.

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An agency of HSE

Annex 2

GDA ISSUE
USE OF ETC-C FOR THE DESIGN AND CONSTRUCTION OF THE UK EPR™
GI-UKEPR-CE-02 REV 1

Technical Area CIVIL ENGINEERING

Related Technical Areas None

GDA Issue GI-UKEPR-CE-02 GDA Issue Action GI-UKEPR-CE-02.A4

Reference Reference

GDA Issue Provide a revision of the UK companion document which addresses the
Action observations raised AFCEN ETC-C Part 2 as a result of our assessment, the key
points being:
 Insufficient information to be the basis of a clear construction specification
 Links to French ministerial standards are of no relevance to the UK
 Clarification of the intention to demonstrate the equivalence of French
standards to other national standards
 Provide clarity over the approval of modifications or adaptations to the
specification
 Provide clarity over how demonstration of equivalence would be achieved
In addition, please provide a mapping document (i.e. updated ETC-C assessment
file) which identifies how these points have been dealt with.

With agreement from the Regulator this action may be completed by alternative
means.

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