IIunI=U-U10U

(Formerly NUREG-75/087)

PI> UAS NUCLEAR REGULATORY COMMISSION

'X t STANDARD REVIEW PLAN

OFFICE OF NUCLEAR REACTOR REGULATION

3.9.3 ASME CODE CLASS 1, 2, AND 3 COMPONENTS, COMPONENT SUPPORTS, AND CORE
SUPPORT STRUCTURES
REVIEW RESPONSIBILITIES

Primary - Mechanical Engineering Branch (MEB)

Secondary - None

I. AREAS OF REVIEW
The MEB reviews the information presented in the applicant's safety analysis
report (SAR) concerning the structural integrity of pressure-retaining components,
their supports, and core support structures which are designed in accordance with
the rules of the American Society of Mechanical Engineers (ASME) Boiler and Pres-
sure Vessel Code, Section III, Division 1 (hereinafter "the Code") (Reference 3)
and General Design Criteria 1, 2, 4, 14, and 15 (Reference 2).
The staff reviews covers the following specific areas:
1. Loading Combinations, System Operating Transients, and Stress Limits
The design and service loading combinations (e.g., design and service loads,
including system operating transients, in combination with loads calculated
to result from postulated seismic and other events) specified for Code
constructed items designated as Code Class 1, 2, 3 (including Class 1, 2
and 3 component support structures) and CS core support structures are
reviewed to determine that appropriate design and service -limits have been
designated for all loading combinations. This review ascertains that the
design and service stress limits and deformation criteria comply with the
applicable limits specified in the Code and Appendix A to this SRP section.
Service stress limits which allow inelastic deformation of Code Class 1, 2,
and 3 components, component supports, .and Class CS core support structures
are evaluated as are the justifications for the proposed design procedures.
Piping which is "field run" should be included. Internal parts of components,
such as valve discs and seats and pump shafting, subjected to dynamic loading
during operation of the component should be included.

Rev. 1 - July 1981

USNRC STANDARD REVIEW PLAN
Standard review plans are prepared for the guidance of the Qifice of Nuclear Reactor Regulation staff responsible for the review of
applications to construct and operate nuclear power plants. These documents are made available to the public as part of the
Commission's policy to Inform the nuclear Industry and the general public of regulatory procedures and policies. Standard review
plans are not substitutes for regulatory guides or the Commission's regulations and compliance with them Is not required. The
standard review plan sections are keyed to the Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants.
Not all sections of the Standard Format have a corresponding review plan.
Published standard review plans will be revised periodically. as appropriate, to accommodate comments and to reflect new Informa-
tion and experience.
comments and suggestions for Improvement will be considered and should be sent to the U.S. Nuclear Regulatory Commission,
Office of Nuclear Reactor Regulation. Washington. D.C. 2355
2. Design and Installation of. Pressure Relief Devices
The design and installation criteria applicable to the mounting of pressure
relief devices (safety valves and relief valves) for the overpressure protec-.
tion of Code Class 1, 2, and 3 components are reviewed. The review includes
evaluation of the applicable loading combinations and stress criteria.
The design review extends to consideration of the means provided to accommo-
date the rapidly applied reaction force when a safety valve or relief valve
opens, and the transient fluid-induced loads applied to the piping downstream
of a safety or relief valve in a closed discharge piping system. The dynamic
structural response due to BWR safety relief valve discharge into the suppres-
sion pool is also considered.
The design of safety and relief valve systems is reviewed with respect to
the load combinations imposed on the safety or relief valves, upstream
piping or header, downstream or vent piping, system supports, and BWR
suppression pool discharge devices such as ramsheads and quenchers.
The load combinations should identify the most severe combination of the
applicable loads due to internal fluid weight, momentum and pressure, dead
weight of valves and piping, thermal load under heatup, steady state and
transient valve operation, reaction forces when valves are discharging
(thrust, bending, and torsion), seismic forces, and dynamic forces due to
BWR safety relief valve discharge into the suppression pool as applicable.
The reaction loads due to discharge of loop seal water slugs and subcooled
or saturated liquid under transient or accident conditions shall also be
included as valve discharge loads.
The structural response of the piping and support system is reviewed with
particular attention to the dynamic or time-history analyses employed in
evaluating the appropriate support and restraint stiffness effects under
dynamic loadings when valves are discharging.
Where the use of hydraulic snubbers is proposed, the snubber performance
characteristics are reviewed to assure that their effects have been
considered in the analyses under steady state valve operation and repeti-
tive load applications caused by cyclic valve opening and closing during
the course of a pressure transient.
3. Component Supports
The review of information submitted by the applicant includes an evaluation
of Code Class 1, 2, and 3 components supports. The review includes an
assessment of design and structural integrity of the supports. The review
addresses three types of supports: plate and shell, linear, and component
standard types. All the component supports of these three types are
covered in this SRP section. Although classified as component standard
supports, snubbers require special consideration due to their unique
function. Snubbers provide no load path or force transmission during
normal plant operations but function as rigid supports when subjected to
dynamic transient loads. Component supports are those metal supports
which are designed to transmit loads from the pressure-retaining boundary
of the component to the building structure. The methods of analysis for
calculating the responses of the reactor coolant pressure boundary supports
resulting from the combination of LOCA and SSE events are reviewed in SRP
Sections 3.6.2 and 3.9.2.

3.9.3-2 Rev. 1 - July 1981

In addition, the MEB will coordinate other branches evaluations that interface
with the overall review of this SRP section as follows: The Equipment Qualifica-
tion Branch (EQB) evaluates the operability of pumps and valves and judges the
design criteria for pressure-relieving devices which may have an active function
during and after a faulted plant condition against the requirements of the
component operability assurance program as part of its primary review respon-
sibility for SRP Section 3.10. The Auxiliary Systems Branch (ASB) verifies
that the number and size of valves specified for the steam and feedwater systems
have adequate pressure-relieving capacity as part of its primary review responsi-
bility for SRP Section 10.3. The Reactor Systems Branch (RSB) verifies that
the number and size of valves specified for the reactor coolant pressure boundary
have adequate pressure-relieving capacity as part of its primary review responsi-
bility for SRP Section 5.2.2. The Containment Systems Branch (CSB) reviews
the applicant's analyses of subcompartment differential pressures resulting
from postulated pipe breaks as part of its primary review responsibility for
SRP Section 6.2.1.2.
For those areas of review identified above as being reviewed as part of the
primary review responsibility of other branches, the acceptance criteria
necessary for the review and their methods of application are contained in the
referenced SRP section of the corresponding primary branch.
II. ACCEPTANCE CRITERIA
?4EB acceptance criteria are based on meeting the relevant requirements of the
following regulations:
A. 10 CFR Part 50, §50.55a and General Design Criterion 1 as it relates to
structures and components being designed, fabricated, erected, constructed,
tested, and inspected to quality standards commensurate with the importance
of the safety function to 6e performed.

B. General Design Criterion 2 as it relates to structures and components

important to safety being designed to withstand the effects of earthquakes
combined with the effects of normal or accident conditions.
C. General Design Criterion 4 as it relates to structures and components
important to safety being designed to accommodate the effects of and to
be compatible with the environmental conditions of normal and accident
conditions.
D. General Design Criterion 14 as it relates to the reactor coolant pressure
boundary being designed, fabricated, erected, and tested to have an extremely
low probability of abnormal leakage, of rapidly propagating failure, and
of gross rupture.

E. General Design Criterion 15 as it relates to the reactor coolant system

being designed with sufficient margin to assure that the design conditions
are not exceeded.
Specific criteria necessary to meet the relevant requirements of §50.55a and
General Design Criteria 1, 2, 4, 14, and 15 by which the areas of review defined
in subsection I of this SRP section judged to be acceptable are as follows:

'3.
9.3-3 Rev. 1 - July 1981
1. Loading Combinations, System Operating Transients, and Stress Limits
The design and service loading combinations, including system operating
transients, and the associated design and service stress limits considered
for each component and its supports should be sufficiently defined to
provide the basis for design of Code Class 1, 2, and 3 components, component
supports and Class CS core support structures for all conditions.
The acceptability of the combination of design and service loadings (includ-
ing system operating transients), applicable to the design of Class 1, 2,
and 3 components, component supports, and Class CS core support structures,
and of the designation of the appropriate design or service stress limit
for each loading combination, is judged by comparison with positions stated
in Appendix A, and with appropriate standards acceptable to the staff
developed by professional societies and standards organizations.
The design criteria for internal parts of components such as valve discs,
seats, and pump shafting should comply with applicable ASME Code or Code
Case criteria. In those instances where no ASME criteria exist, the design
criteria are acceptable if they assure the structural integrity of the
part such that no safety-related functions are impaired.
2. Design and Installation of Pressure Relief Devices
The applicant should use design criteria for pressure relief stations
specified in Appendix 0, ASME Code, Section III, Division 1, "Rules for
the Design of Safety Valve installations" (Reference 6). Additionally,
the following criteria are applicable:
(1) Where more than one valve is installed on the same run pipe, the
sequence of valve openings to be assumed in analyzing for the stress
at any piping location should be that sequence which is estimated to
induce the maximum instantaneous value of stress at that location.
(2) Stresses should be evaluated, and applicable stress limits should be
satisfied for all components of the run pipe and connecting systems
and the pressure relief valve station including supports and all
connecting welds between these components.
(3) In meeting the stress limit requirements, the contribution from the
reaction force and the moments resulting from that force should include
the effects of the Dynamic Load Factor or should use the maximum
instantaneous values of forces and moments for that location as deter-
mined by the dynamic hydraulic/structural system analysis. This
requirement should be satisfied in demonstrating satisfaction of all
design limits at all locations of the run pipe and the pressure relief
valve for Class 1, 2, and 3 piping. A Dynamic Load Factor (DLF) of
2.0 may be used. in lieu of a dynamic analysis to determine the DLF.
The SAR must also include a description of the calculational procedures,
computer programs, and other methods to be used in the analysis. The
analysis must include the time history or equivalent effects of changes
of momentum due to fluid flow changes of direction. The fluid states
considered must include postulated water slugs where water seals are used
and subcooled or saturated liquid if such fluid can be discharged under
postulated transient or accident conditions. Plants utilizing suppression

3.9.3-4 Rev. 1 - July 1981

 pools shall also consider the applicable pool dynamic loads on the safety
relief valve system. Stress computations and stress limits must be in
1
accord with applicable rules of the Code.

3. Component Supports
a. The component support designs should provide adequate margins of
safety under all combinations of loadings. The combination of load- I
ings (including system operating transients) considered for each
component support within a system, including the designation of the
appropriate service stress limit for each loading combination should
meet the criteria in Appendix A and Regulatory Guides 1.124 and 1.130
(References 7 and 8).
Component supports of active pumps and valves should be considered
in context with the other features of the operability assurance pro-
gram as presented in SRP Section 3.10. If the component support
affects the operability requirements of the supported component, then
deformation limits should also be specified. Such deformation limits
should be compatible with the operability requirements of the components
supported and incorporated into the operability assurance program.
In establishing allowable deformations, the possible movements of
the support base structures must be taken into account.
b. Where snubbers are utilized as supports for safety-related systems
and components, acceptable criteria for snubber operability assurance
should contain the following elements:
(1) Structural Analysis and Systems Evaluation.

Systems and components which utilize snubbers as shock and vibra-

tion arrestors must be analyzed to ascertain the interaction of
such devices with the systems and components to which they are
attached. Snubbers may be used as shock and vibration arrestors
and in some instances as dual purpose snubbers. When used as a
vibration arrestor or dual purpose snubbers, fatigue strength
must be considered. Important factors in the fatigue evaluation
include: (i) unsupported system component movement or amplitude,
(ii) force imparted to snubber and corresponding reaction on
system or component due to restricting motion (damped amplitude),
(iii) vibration frequency or number of load cycles, and (iv)
verification of system or component and snubber fatigue strength.
Snubbers used as shock arrestors do not require fatigue evaluation
if it can be demonstrated that (i) the number of load cycles
which the snubber will experience during normal plant operating
conditions is small (<2500) or (ii) motion during normal plant
operating conditions does not exceed snubber dead band.
Snubbers utilized in systems or components which may experience
high thermal growth rates either during normal operating condi-
tions or as a result of anticipated transients should be checked
to assure that such thermal growth rates do not exceed the snubber
lock-up velocity.

3.9.3-5 Rev. 1 - July 1981

(2) Characterization of Mechanical Properties.
A most important aspect of the structural analysis is realistic
characterization of snubber mechanical properties (i.e. spring
rates) in the analytical model. Since the "effective" stiffness
of a snubber is generally greater than that for the snubber
support assembly (i.e., the snubber plus clamp, transition tube
extension, back-up support structure, etc.) the snubber response
characteristics may be "washed out" by the added flexibility in
the support structure. The combined effective stiffness of the
snubber and support assembly must therefore be considered in
evaluating the structural response of the system or component.
Snubber spring rate should be determined independent of clearance/
lost motion, activation level, or release rate. The stiffness
should be based on structural and hydraulic compliance only,
and should consider the effects of temperature.
The snubber end fitting clearance and lost motion must be mini-
mnized and should be considered when calculating snubber reaction
loads and stress which are based on a linear analysis of the
system or component. This is especially important in multiple
snubber applications where mismatch of end fitting clearance
has a greater effect on the load sharing of these snubbers than
does the mismatch of activation level or release rate. Equal
load sharing of multiple snubber supports should not be assumed
if mismatch in end fitting clearance exists.

(3) Design Specifications

The required structural and mechanical performance of snubbers
is determined from the user's system analysis described in (1)
and (2). The snubber Design Specification is the instrument
provided by the purchaser to the supplier to assure that the
requirements are met. The Design Specification should contain
(i) the general functional requirements, (ii) operating environ-
ment, (iii) applicable codes and standards, (iv)materials of
construction and standards for hydraulic fluids and lubricants,
(v) environmental, structural, and performance design verification
tests, (vi) production unit functional verification tests and
certification, (vii) packaging, shipping, handling, and storage
requirements, and (viii) description of provisions for attachments
and installation.
In addition, the snubber manufacturer should be requested to
submit his quality assurance and assembly quality control
procedures for review and acceptance by the purchaser.

(4) Installation and Operability Verification

Assurance that all snubbers and properly installed prior to
preoperational piping vibration and plant start-up tests should
be provided. Visual observation of piping systems and measure-
ment of thermal movements during plant start-up tests could
verify that snubbers are operable (not locked up). Provisions
for such examinations and measurements should be discussed in

3.9.3-6 Rev. 1 - July 1981

 the piping preoperational vibration and plant start-up test
programs as described in SRP Section 3.9.2.
(5) Use of Additional Snubbers
Snubbers could in some instances be installed during or after
plant construction which may not have been included in the design
analysis. This could occur as a result of unanticipated piping
vibration as discussed in SRP Section 3.9.2 or interference
problems during construction. The effects of such installation
should be fully evaluated and documented to demonstrate that
normal plant operations and safety are not diminished.

(6) Inspection and Testing

Inservice inspection and testing are critical elements of oper-
ability assurance programs for mechanical components. The appli-
cant should provide a discussion of accessibility provisions
for maintenance, inservice inspection and testing, and possible
repair or replacement of snubbers consistent with the requirements
of the NRC Standard Technical Specifications.
(7) Classification and Identification

All safety-related components which utilize snubbers in their

support systems should be identified and tabulated in the FSAR.
The tabulation should include the following Information: (I)
identification of the systems and components in those systems
which utilize snubbers, (ii)the number of snubbers utilized in
each system and on components in that system, (iii) the type(s)
of snubber (hydraulic or mechanical) and the corresponding
supplier identified, (iv) specify whether the snubber was
constructed to the rules of ASME Code Section III, Subsection
NF, (v) state whether the snubber is used as a shock, vibration,
or dual purpose snubber, and (vi) for snubbers identified as
either dual purpose or vibration arrestor type, indicate if both
snubber and component were evaluated for fatigue strength.
III. REVIEW PROCEDURES

The reviewer will select and emphasize material from the procedures described
below,.as may be appropriate for a particular case.
For each area of review, the following review procedures apply:
1. Loading Combinations, System Operating Transient, and Stress Limits
The objectives in reviewing the loading combinations and stress limits
employed by the applicant in the design of Code Class 1, 2, and 3 compo-
nents, component supports, ahd Class CS core support structures are to
confirm that the appropriate postulated events have been included, that
the loading combinations (including system operating transients) and the
designation of design and service stress limits are appropriate. The
review conducted during the CP stage determines that the objectives have
been addressed and are being implemented in the design by obtaining a
commitment from the applicant that specific design criteria will be utilized.

3.9.3-7 Rev. 1 - July 1981

 By checking selected Code required Design Documents such as Design Reports,
Load Capacity Data Sheets, and related material, the OL stage review verifies
that the design criteria have been utilized and that components have been
designed to meet the objectives. To assure that these objectives are met,
the review is performed as follows:
a. The applicant's proposed design and service loadings, and combina-
tions thereof, are reviewed for completeness and for. appropriate
designation of corresponding design and service stress limits.
b. The combination of design and service loadings, including procedures
for combination, proposed by the applicant for each Code-constructed
item are reviewed to determine if they are adequate. This aspect of
the review is made by comparison with the loading combinations and
procedures for combination set forth in Appendix A. Deviations from
the position are evaluated on a case-by-case basis by questions
addressed to the applicant to determine the rationale and justifica-
tion for exceptions. Final determination is based on engineering
judgment and past experience with prior applications.
c. The design and service stress limits selected by the applicant for
each set of design and service loading combinations as established
in (a) are reviewed to determine if they meet those specified in
Appendix A. The provisions for piping component functional capability
are reviewed to determine their adequacy in meeting the objectives
set forth in Appendix A. Deviations from the position may be permitted
provided Justification is presented by the applicant. The acceptability
determination is based on considerations of adequate margins of safety.
2. Design and Installation of Pressure Relief Devices
The objective of the review of the design and installation of pressure
relief devices is to assure the adequacy of the design and installation
so that there is assurance of the integrity of the pressure relieving
devices and associated piping during the functioning of one or more of
the relief devices. In the CP review, it is determined whether there is
reasonable assurance that the final design will meet these objectives.
At the OL stage, the final design is reviewed to determine that the objec-
tives have been met.
The review is performed as follows:
a. The design of the pressure retaining boundary of the device is
reviewed by comparison with the Code. Since explicit rules are not
yet available within the Code for the design of safety and pressure
relief valves, the design is reviewed on the basis of reference to
sections of the Code on vessels, piping, and line valves, and ASME
Code Case N-100 (Reference 6).
Allowable stress limits are compared with those in the Code for the
appropriate class of construction. Deviations are identified and
the applicant is requested to provide justification. Stress limits
and loading combinations are covered under the areas entitled "Loading
Combinations, System Operating Transients, and Stress Limits" in this
SRP section.

3.9.3-8 Rev. 1 - July 1981

 b. The design of the installation is reviewed for structural adequacy
to withstand the dynamic effects of relief valve operation. The
applicant should include and discuss: reaction force, valve opening
sequence, valve opening time, method of analysis, and magnitude of a
dynamic load factor (if used). In reaching an acceptance determination,
the reviewer compares the submission with the requirements in subsec-
tion II.2 of this SRP section.

Where deviations occur, they are identified and the justification is

evaluated. Valve opening sequence effects must consider the worst
combination possible and forcing functions must be justified with
valve opening time data. The review is based in part on comparisons
with prior acceptable designs tested in operating plants.
3. Component Supports
The objective in the review of component supports is to determine that
adequate attention has been given the various aspects of design and analysis,
so that there is assurance as to structural integrity of supports and as
to operability of active components that interact with component supports.
The reviewer should be assured that the applicant's PSAR contains discussions
and commitments to develop and utilize a snubber operability assurance
program containing the elements specified in paragraphs (1) through (6)
of subsection II.3.b of this SRP section. A commitment to provide in the
FSAR the information specified in paragraph (7) of subsection II.3.b of
this SRP section is sufficient for the CP review stage. During the OL
review the FSAR should contain summaries in sufficient detail to verify
the PSAR commitments.

The structural integrity of the three types of component supports described

in subsection I.3 of this SRP section are reviewed against the criteria
and guidelines of subsection II.3 of this SRP section.
IV. EVALUATION FINDINGS

The reviewer verifies that sufficient information has been provided in accordance
with the requirements of this SRP section, and that his evaluation supports
conclusions of the following type, to be included in the staff's safety evaluation
report:
The staff concludes that the specified design and service combinations of load-
ings as applied to ASME Code Class 1, 2, and 3 pressure retaining components
are acceptable and meet the requirements of 10 CFR Part 50, §50.55a and General
Design Criteria 1, 2, 4, 14, and 15. This conclusion is based on the following:
1. The applicant met the requirements of 10 CFR Part 50, §50.55a and General
Design Criteria 1, 2, and 4 with respect to the design and service load
combinations and associated stress and deformation limits specified for
ASME Code Class 1, 2, and 3 components by insuring that systems and
components important to safety are designed to quality standards commen-
surate with their importance to safety and that these systems can accom-
modate the effects of normal operation as well as postulated events such
as loss-of-coolant accidents and the dynamic effects resulting from earth-
quakes. The specified design and service combinations of loadings as
applied to ASME Code Class 1, 2, and 3 pressure retaining components in

3.9.3-9 Rev. 1 - July 1981

 systems designed to meet seismic Category I standards are such as to
provide assurance that in the event of an earthquake affecting the site
or other service loadings due to postulated events or system operating
transients, the resulting combined stresses imposed on system components
will not exceed allowable stress and strain limits for the materials of
construction. Limiting the stresses under such loading combinations
provides a conservative basis for the design of system components to
withstand the most adverse combination of loading events without loss of
structural integrity.
2. The applicant has met the requirements of 10 CFR Part 50, §50.55a and
General Design Criteria 1, 2, and 4 with respect to the criteria used for
design and installation of ASME Code Class 1, 2, and 3 overpressure
relief devices by insuring that safety and relief valves and their
installations are designed to standards which are commensurate with their
safety functions, and that they can accommodate the effects of discharge
due to normal operation as well as postulated events such as loss-of-
coolant accidents and the dynamic effects resulting from the safe
shutdown earthquake. The relevant requirements of General Design
Criteria 14 and 15 are also met with respect to assuring that the reactor
coolant pressure boundary design limits for normal operation including
anticipated operational occurrences are not exceeded. The criteria used
by the applicant in the design and installation of ASME Class 1, 2, and 3
safety and relief valves provide adequate assurance that, under discharging
conditions, the resulting stresses will not exceed allowable stress and
strain limits for the materials of construction. Limiting the stresses
under the loading combinations associated with the actuation of these
pressure relief devices provides a conservative basis for the design and
installation of the devices to withstand these loads without loss of
structural integrity or impairment of the overpressure protection
function.
3. The applicant has met the requirements of 10 CFR Part 50, §50.55a and
General Design Criteria 1, 2, and 4 with respect to the design and
service load combinations and associated stress and deformation limits
specified for ASME Code Class 1, 2, and 3 component supports by insuring
that component supports important to safety are designed to quality
standards commensurate with their importance to safety, and that these
supports can accommodate the effects of normal operation as well as
postulated events such as loss-of-coolant accidents and the dynamic
effects resulting from the safe shutdown earthquake. The combination of
loadings (including system operating transients) considered for each
component support within a system, including the designation of the
appropriate service stress limit for each loading combination, has met
the positions and criteria of Regulatory Guides 1.124 and 1.130 and are
in accordance with NUREG-0484.and NUREG-0609. The specified design and
service loading combinations used for the design of ASME Code Class 1, 2,
and 3 component supports in systems classified as seismic Category I
provide assurance that in the event of an earthquake or other service
loadings due to postulated events or system operating transients, the
resulting combined stresses imposed on system components will not exceed
allowable stress and strain limits for the materials of construction.
Limiting the stresses under such loading combinations provides a
conservative basis for the design of support components to withstand the
most adverse combination of loading events without loss of structural
integrity.

3.9.3-10 Rev. 1 - July 1981

Class CS component evaluation findings are covered in SRP Section 3.9.5 in I
connection with reactor internals.
V. IMPLEMENTATION
The following is intended to provide guidance to applicants and licensees
regarding the NRC staff's plans for using this SRP section.
Except in those cases in which the applicant proposes an acceptable alternative
method for complying with specified portions of the Commission's regulations,
the method described herein will be used by the staff in its evaluation of
conformance with Commission regulations.
Implementation schedules for conformance to parts of the method discussed
herein are contained in the referenced regulatory guides and NUREGs.
VI. REFERENCES

1. 10 CFR Part 50, §50.55a, "Codes and Standards."

2. 10 CFR Part 50, Appendix A, "General Design Criteria for Nuclear Power
Plants," (a) General Design Criterion 1, "Quality Standards and Records,"
(b) General Design Criterion 2, "Design Bases for Protection Against
Natural Phenomena," (c) General Design Criterion 4, "Environmental and
Missile Design Bases," Cd) General Design Criterion 14, "Reactor Coolant
Pressure Boundary," and (e) General Design Criterion 15, "Reactor Coolant
System Design."
3. ASME Boiler and Pressure Vessel Code, Section III, Division 1, "Nuclear
Power Plant Components," American Society of Mechanical Engineers.
4. Standard Review Plan Section 3.10, "Seismic and Dynamic Qualification of
Mechanical and Electrical Equipment Important to Safety."
5. Appendix A to SRP Section 3.9.3, "Stress Limits for ASME Class 1, 2, and
3 Components and Component Supports of Safety-Related Systems and Class
CS Core Support Structures Under Specified Service Loading Combinations."
6. ASME Code Case N-100, "Pressure Relief Valve Design Rules, Section III,
Division 1, Class 1, 2 and 3."
7. Regulatory Guide 1.124, "Design Limits and Loading Combinations for
Class 1 Linear-Type Component Supports."
8. Regulatory Guide 1.130, "Design Limits and Loading Combinations for
Class 1 Plate- and Shell-Type Component Supports."
9. NUREG-0484, "Methodology for Combining Dynamic Loads."
10. NUREG-0609, "Asymmetric Blowdown Loads on PWR Primary Systems."

3-9.3-11 Rev. 1 - July 1981

 APPENDIX A
STANDARD REVIEW PLAN SECTION 3.9.3
STRESS LIMITS FOR ASME CLASS 1, 2, AND 3 COMPONENTS AND COMPONENT
SUPPORTS OF SAFETY-RELATED SYSTEMS AND CLASS CS CORE SUPPORT STRUCTURES
UNDER SPECIFIED SERVICE LOADING COMBINATIONS

A. INTRODUCTION
Nuclear power plant components and supports are subjected to combinations of
loadings derived from plant and system operating conditions, natural phenomena,
postulated plant events, and site-related hazards. Section III, Division 1 of
the ASME Code (hereafter referred to as the Code) provides specific sets of
design and service stress limits that apply to the pressure retaining or
structural integrity of components and supports when subjected to these
loadings. The design and service stress limits specified by the Code do not
assure, in themselves, the operability of components, including their supports,
to perform the mechanical motion required to fulfill the component's safety
function. Certain of the service stress limits specified by the Code (i.e.,
level C and D) may not assure the functional capability of components,
including their supports, to deliver rated flow and retain dimensional
stability. Since the combination of loadings, the selection of the applicable
design and service stress limits appropriate to each load combination and the
proper consideration of operability is beyond the scope of the Code; and the
treatment of functional capability, including collapse and deflection limits,
is not adequately treated by the Code for all situations, such factors must be
evaluated by designers and appropriate information developed for inclusion in
the Design Specification or other referenced documents.
Applicants require guidance with regard to the selection of acceptable design
and service stress limits associated with various loadings and combinations
thereof, resulting from plant and system operating conditions and design basis
events, natural phenomena, and site-related hazards. The relationship and
application of the terms "design conditions," "plant operating conditions,"
"system operating conditions," and the formerly used term "component operating
conditions," now characterized by four levels of service stress limits, have
not been clearly understood by applicants and their subcontractors.
For example, under the "faulted plant or system condition" (e.g., due to LOCA
within the reactor coolant.pressure boundary), the emergency core cooling
system (ECCS) should be designed to operate and deliver rated flow for an
extended period of time to assure the safe shutdown of the plant. Although the
"plant condition" is termed "faulted," components in the functional ECCS must
perform the safety function under a specified set of service loadings which
includes those resulting from the specified plant postulated events. The
selection of level "D" (related to the "faulted" condition) service stress
limits for this system, based solely on the supposition that all components may
use this limit for a postulated event resulting in the faulted plant condition
cannot be justified, unless system operability is also demonstrated.

This appendix is necessary to improve consistency and understanding of the

basic approach in the selection of load combinations applicable to safety-
related systems and to establish acceptable relationships between plant
postulated events, plant and system operating conditions, component and

3.9.3-12 Rev. 1 - April 1984

component support design, and service stress limits, functional capability, and
operability.
B. DISCUSSION
Current reviews of both standardized plants and custom plants have indicated
the need for additional guidance to reach acceptable design conclusions in the
following areas:
(1) Relationship between certain plant postulated events, plant and system
operating conditions, resulting loads and combinations thereof, and
appropriate design and service stress limits for ASME Class 1, 2 and 3
components and component supports and Class CS core support structures.

(2) Relationship of component operability assurance, functional capability,

and allowable design and service stress limits for ASME Class 1, 2, and 3
components and component supports.

The Code provides five categories of limits applicable to design and service
-loadings (design, level A, level B, level C, and level D). The Code rules
provide for structural integrity of the pressure retaining boundary of a
component and its supports, but specifically exclude the subject of component
operability and do not directly address functional capability. The types of
loadings to be taken into account in designing a component are specified in the
Code, but rules specifying how the loadings, which result from postulated
events and plant and system operating conditions, are to be combined and what
stress level is appropriate for use with loading combinations are not specified
in the Code. It is the responsibility of the designer to include all this
information in the Code required Design Specification of each component and
support.
C. POSITION
Effective with the 1977 Edition, the Code provides design stress limits and
four sets of service stress limits for all classes of components, component
supports, and core support structures. The availability of such design and
service stress limits within the Code requires that the MEB review and deter-
mine maximum acceptable design and service stress limits which may be used with
specified loads, or combinations thereof, for components and component supports
of safety-related systems (refer to definition in Table III) and core support
structures.
This appendix provides guidance for dealing with the components and component
supports of safety-related systems and core support structures in the following
areas:
(1) Consideration of design loadings and limits.
(2) Consideration of service loading combinations resulting from postulated
events and the designation of acceptable service limits.

3.9.3-13 Rev. 1 - April 1984

(3) Consideration of piping functional capability and operability of active
pumps and valves under service loading combinations resulting from
postulated events.

(4) Applicability of the appendix to components, component support structures,

and core support structures and procedures for compliance.

1.0 ASME CLASS 1, 2, AND 3 COMPONENTS AND COMPONENT SUPPORTS OF SAFETY-RELATED

SYSTEMS AND CLASS CS CORE SUPPORT STRUCTURES

1.1 Design Considerations and Design Loadings

ASME Code Class 1, 2, and 3 components, component supports, and class CS

core support structures shall be designed to satisfy the appropriate sub-
sections of the Code in all respects, including limitations on pressure,
and the requirements of this appendix. Component supports that are
intended to restrain either force and displacement or anchor movement
shall be designed to maintain deformations within appropriate limits as
specified in the component support Design Specifications.

Design loadings shall be established in the Design Specification. The

design limits of the appropriate subsection of the Code shall not be
exceeded for the design loadings specified.

1.2 Service Loading Combinations

The identification of individual loads and the appropriate combination of

these loads (i.e., sustained loads, loads due to system operating
transients SOT, OBE, SSE, LOCA, DBPB, MS/FWPB and their dynamic effects)
shall be in accordance with Section 1.3. The appropriate method of
combination of these loads shall be in accordance with NUREG-0484,
"Methodology for Combining Dynamic Loads" (Reference 9).

1.3 Service Conditions

1.3.1 Service Limit A

Class 1, 2, and 3 components, component supports, and Class CS core

support structures shall meet a service limit not greater than Level A
when subjected to sustained loads resulting from normal plant/system
operation.

1.3.2 Service Limit B

Class 1, 2, and 3 components, component supports, and Class CS core

support structures shall meet a service limit not greater than Level B
when subjected to the appropriate combination of loadings resulting from
(1) sustained loads, (2) specified plant/system operating transients
(SOT), and (3) the OBE.

1.3.3 Service Limit C

(a) Class 1, 2, and 3 components, component supports, and Class CS core

support structures shall meet a service limit not greater than Level

3.9.3-14 Rev. 1 - April 1984

 C when subjected to the appropriate combination of loadings resulting
from (1) sustained loads, and (2) the DBPB.
(b) The DBPB includes loads from the postulated pipe break, itself, and
also any associated system transients or dynamic effects resulting
from the postulated pipe break.

1.3.4 Service Limit 0

(a) Class 1, 2, and 3 components, component supports, and Class CS core
support structures shall meet a service stress limit not greater than
Level D when subjected to the appropriate combination of loadings
resulting from (1) sustained loads, (2) either the DBPB, MS/FWPB, or
LOCA, and (3) and SSE.

(b) The DBPB, MS/FWPB, and LOCA include loads from the postulated pipe
breaks, themselves, and also any associated system transients or
dynamic effects resulting from the postulated pipe breaks. Asymme-
tric blowdown loads on PWR primary systems shall be incorporated per
NUREG-0609 (Reference 10).
2.0 OPERABILITY AND FUNCTIONAL CAPABILITY

2.1 Active Pumps and Valves

SRP Section 3.10 (Reference 4) shall demonstrate that the pump or valve,
as supported, can adequately sustain the designated combined service
loadings at a stress level at least equal to the specified service limit,
and can perform its safety function without impairment. Loads produced by
the restraint of free end displacement and anchor point motions shall be
included.

2.2 Snubbers

The operability requirements specified for mechanical and hydraulic

snubbers installed on safety-related systems is subject to review by the
staff. When snubbers are used, their need shall be clearly established
and their design criteria presented.
2.3 Functional Capability

The design of Class 1, 2, and 3 piping components shall include a

functional capability assurance program. This program shall demonstrate
that the piping components, as supported, can retain sufficient dimen-
sional stability at service conditions so as not to impair the system's
functional capability. The program may be based on tests, analysis, or a
combination of tests and analysis.

3.0 TABLES

3.1 Table I summarizes the requirements of this appendix for use with ASME
Class 1, 2, and 3 components, component supports, and Class CS core
support structures. The table illustrates plant events, system operating

3.9.3-15 Rev. 1 - April 1984

 conditions, service loading combinations, and service stress limits and
should always be used in conjunction with the text of this appendix.
3.2 Table II defines all the terms used in this appendix.
4.0 PROCEDURES FOR COMPLIANCE
4.1 Design Specification and Safety Analysis Report
(a) The design options provided by the Code and related design criteria
specified in the Code required Design Specification for ASME Class 1,
2, and 3 components, component supports, and Class CS core support
structures should be summarized in sufficient detail in the Safety
Analysis Report of the application to permit comparison with this
Appendix.

(b) The presentation in the PSAR should specify and account for all
design and service loadings, method of combination, the designation
of the appropriate design and service stress limits (including
primary and secondary stresses, fatigue consideration, and special
limits on pressure when appropriate) for each loading combination
presented, and the provisions for functional capability.

(c) The presentation in the FSAR should indicate how the criteria in
Sections 1 and 2 of this appendix have been implemented.
(d) The staff may request the submission of the Code required Design
Documents such as Design Specifications, Design Reports, Load
Capacity Data Sheets, or other related material or portions thereof
to establish that the design criteria, the analytical methods, and
functional capability satisfy the guidance provided by this appendix.
This may include information provided to, and received from,
component and support manufacturers. As an alternative to the
applicant submitting these documents, the staff may require them to
be made available for review at the applicant's or vendor's office.
4.2 Use with Regulatory Guides
The information and requirements contained in this appendix supersede
those in the October 1973 version of Regulatory Guide 1.67 and the
May 1973 version of Regulatory Guide 1.48. Regulatory Guides 1.124 and
1.130 on Class 1 linear and Class 1 plate and shell component support
structures are to be supplemented by this appendix.

3.9.3-16 Rev. 1 - April 1984

 TABLE I
Allowable Service Stress Limits for Specified Service Loading Combinations for
ASME Class 1 Components and Class CS Support Structures
System Service Service Stress
Plant Event2 Operating Conditions Loading Combination1 ,4 Limit

1. Normal Operation Normal Sustained Loads A

2. Plant/System Operating Upset Sustained Loads + SOT + OBE B3

Transients (SOT) + OBE
3. DBPB Emergency Sustained Loads + DBPB C3

4. MS/FWPB Faulted Sustained Loads + MS/FWPB D3

u0
5. DBPB or MS/FWPB + SSE Faulted Sustained Loads + DBPB or D3
MS/FWPB + SSE
6. LOCA Faulted Sustained Loads + LOCA D3

to 7. LOCA + SSE Faulted Sustained Loads + LOCA + SSE D3

CAi
NOTE: 1 The appropriate method of combination is subject to review and evaluation. Refer to Section 1.2.
I
2 Refer to Table II for definition of terms.

3In addition to meeting the specified service stress limits for given load combinations, operability and
functional capability must also be demonstrated as discussed in Subsection 2.0 of this appendix and in
za SRP Section 3.10.
~1
4 Theseevents must be considered in the pipe stress analysis and pipe support design process when
-A
specified in the ASME Code-required Design Specification. The Design Specification shall define the
load and specify the applicable Code Service Stress Limit. For clarification, it should be noted
-AD that the potential for water hammer and water (steam) hammer occurrence should also be given proper
consideration in the development of Design Specifications.
 TABLE II

DEFINITION OF TERMS

Active Pumps and Valves - A pump or valve which must perform a mechanical
motion in order to shut down the plant or mitigate the consequences of a
postulated event. Safety and relief valves are specifically included.

Component and Support Functional Capability - Ability of a component,

including its supports, to deliver rated flow and retain dimensional stability
when the design and service loads, and their resulting stresses and strains,
are at prescribed levels.

Component and Support Operability - Ability of an active component, including

its support, to perform the mechanical motion required to fulfill its
designated safety function when the design and service loads, and their
resulting stresses and strains, are at prescribed levels.

DBPB - Design Basis Pipe Breaks - Those postulated pipe breaks other than a
LOCA or MS/FWPB. This includes postulated pipe breaks in Class 1 branch lines
that result in the loss of reactor coolant at a rate less than or equal to the
capability of the reactor coolant makeup system.

This condition includes loads from the postulated pipe breaks, itself, and
also any associated system transients or dynamic effects resulting from the
postulated pipe break.

Design Limits - The limits for the design loadings provided in the appropriate
subsection of Section III, Division 1, of the ASME Code.

Design Loads - Those pressures, temperatures, and mechanical loads selected as

the basis for the design of a component.

Functional System - That configuration of components which, irrespective of

ASME Code Class designation or combination of ASME Code Class designations,
performs a particular function (i.e., each emergency core cooling system
performs a single particular function and yet each may be comprised of some
components which are ASME Class 1 and other components which are ASME Code
Class 2).

LOCA - Loss-of-Coolant Accidents - Defined in Appendix A of 10 CFR Part 50 as

"those postulated accidents that result from the loss of reactor coolant, at a
rate in excess of the capability of the reactor coolant makeup system, from
breaks in the reactor coolant pressure boundary, up to and including a break
equivalent in size to the double-ended rupture of the largest pipe of the
reactor coolant system."

3.9.3-18 Rev. 1 - April 1984

This condition includes the loads from the postulated pipe break, itself, and
also any associated system transients or dynamic effects resulting from the
postulated pipe break.
MS/FWPB - Main Steam and Feedwater Pipe Breaks - Postulated breaks in the main
steam and feedwater lines. For a BWR plant this may be considered as a LOCA
event depending on the break location.
This condition includes the loads from the postulated pipe break, itself, and
also any associated system transients or dynamic effects resulting from the
postulated pipe break.
OBE - Operating Basis Earthquake - Defined in Section III (d) of Appendix A of
10 CFR Part 100 as "that earthquake which, considering the regional and local
geology and seismology and specific characteristics of local subsurface
material, could reasonably be expected to affect the plant site during the
operating life of the plant. It is that earthquake which produces the
vibratory ground motion for which those features of the nuclear power plant,
necessary for continued operation without undue risk to the health and safety
of the public, are designed to remain functional."
This condition includes the loads from the postulated seismic event, itself,
and also any associated system transients or dynamic effects resulting from
the postulated seismic event.

Piping Components - These items of a piping system such as tees, elbows,

bends, pipe and tubing, and branch connections constructed in accordance with
the rules of Section III of the ASME Code.
Postulated Events - Those postulated natural phenomena (i.e., OBE, SSE),
postulated site hazards (i.e., nearby explosion), or postulated plant events
(i.e., DBPB, LOCA, MS/FWPB) for which the plant is designed to survive without
undue risk to the health and safety of the public. Such postulated events may
also be referred to as design basis events.
SSE - Safe Shutdown Earthquake - Defined in Section III(c) of Appendix A of
10 CFR Part 100 as "that earthquake which is based upon an evaluation of the
maximum earthquake potential considering the regional and local geology and
seismology and specific characteristics of local subsurface material. It is
the earthquake which produces the maximum vibratory ground motion for which
certain structures, systems, and components are designed to remain functional.
These structures, systems, and components are those necessary to assure:
(1) The integrity of the reactor coolant pressure boundary.
(2) The capability to shut down the reactor and maintain it in a safe
shutdown condition, or
(3) The capability to prevent or mitigate the consequences of accidents which
could result in potential offsite exposures comparable to the guideline."

3.9.3- 19 Rev. 1 - April 1984

This condition includes the loads from the postulated seismic event, itself,
and also any associated system transients or dynamic effects resulting from
the postulated seismic event.

Service Limits - The four limits for the service loading as provided in the
appropriate subsection of Section III, Division 1, of the ASME Code.

Service Loads - Those pressure, temperature, and mechanical loads provided in

the Design Specification.

SOT - System Operating Transients - The transients and their resulting

mechanical responses due to dynamic occurrences caused by plant or system
operation.

3.9.3-20 Rev. 1 - April 1984