Chapter 2

GERMAN NUCLEAR PROGRAM

© M. Ragheb
6/23/2024

2.1 INTRODUCTION
In December of 1938, the German radio-chemist Otto Hahn, born in Frankfurt am
Main, Germany in 1879, and Fritz Strassman, an inorganic chemist born in Boppard,
Germany in 1902, were the first to discover the nuclear fission process and the splitting of
the nucleus of uranium. They were both awarded the Nobel Prize in Chemistry for it in
1944.

Figure 1. Otto Hahn, with Fritz Strassman discovered the process of nuclear fission in
December of 1938.

The views of historians and authors about the German Nuclear Program during
World War II differ substantially.
Some German scientists claimed that they did not want to hand the German Nazi
regime a horrible weapon, based on moral considerations. Another view was that
accidental fires with powdered uranium used in the first subcritical assemblies that they
built discouraged them. Inaccurate calculations about the lattice parameters in a heavy
water-moderated thermal subcritical assembly misled them. The inability to secure
sufficient heavy water (D2O, HDO) from Norway due to bombings and commando raids
and sabotage, or to manufacture it in Germany, blocked their progress. Some of them used
the nuclear research as a pretext to protect themselves and their coworkers from being sent
to the killing fields at the battle fronts. Others did not want to make unachievable claims
about projects they were not confident could be carried out to a successful end, and be
punished if they failed.
Nonetheless, the German nuclear program did in fact build a thermal heavy water
moderated natural uranium subcritical assembly that did not achieve criticality for lack of
sufficient heavy water moderator and natural uranium fuel. This is in contrast to the
graphite moderated critical reactors built on a large industrial scale, and the fast-neutrons
assemblies leading to the construction of nuclear devices in the USA.
The brain drain of a large number of German scientists to the UK and the USA,
caused by the then prevalent religious fanaticism and racism, and unfair treatment, as well
as some German scientists’ overconfidence bordering on arrogance, thinking that they
knew better than their American and British counterparts, doomed them to failure.
Another display of overconfidence was what the German Army set up on June 27,
1940, during World War II, a two-way radio communication system employing a
sophisticated coding machine called “Enigma” to transmit information. The German
military considered its coding system as unbreakable. However, the allies were able to
capture a German submarine and seize its coding machine. The allied cryptographers were
able to break the code and were able to routinely intercept the supposedly secret messages
sent through the system. The Allies were able to locate and sink most of the German
submarine fleet, all while keeping the capture of the submarine secret.
The end result was that the remaining nuclear scientists in Germany never realized
that criticality can be achieved in a miniature fast-neutrons assembly and limited their effort
to a massive thermal neutron heavy water-moderated subcritical experiment that never
achieved criticality up to the end of the war.

2.2 THE BRITISH “MAUD” COMMITTEE

Lise Meitner, a theoretical physicist, born in Vienna, Austria in 1878, who had
worked and corresponded with Otto Hahn, learned through correspondence with him about
the fission process after leaving Germany to England. She communicated the news to Niels
Bohr in Denmark and with her nephew Otto Robert Frisch, a theoretical physicist born in
Vienna, Austria in 1904, developed a theoretical description and the naming of the process
of nuclear fission.
In the UK, Rudolph Peierls, a theoretical physicist, and Otto Frisch wrote a
“Memorandum on the Properties of a Radioactive Super Bomb” using nuclear fission. Otto
Frisch at the University of Birmingham under Mark Oliphant, had worked on the process
of gaseous diffusion, and Rudolph Peierls on the calculation of critical masses.
Mark Oliphant submitted the memorandum to the British Government which
formed the Military Applications of Uranium Disintegration (MAUD) committee to study
the military applications of nuclear fission.
A team of German scientists, led by the theoretical physicist Werner Heisenberg,
born in Wurzburg, Germany in 1901, collected and stockpiled uranium and heavy water
and built subcritical assemblies but did not achieve a self-sustained critical chain reaction.
Werner Heisenberg had pioneered the field of Quantum Mechanics for which he
won the Nobel Prize in Physics in 1932. He met with Niels Bohr in a failed attempt to
reassure him that the efforts of his team were not directed toward the development of a
weapon.
 Carl Friedrichs von Weizäcker came the closest to conceptualizing a weapon by
discussing the production of Neptunium239 from U238, but not the more potent Np237, and
not even Pu239 in a heavy water subcritical assembly which never achieved criticality until
the end of the war.
Harteck and Groth built a laboratory experiment for using an ultracentrifuge for
separating U235 from natural uranium that also did not reach an industrial stage.

Figure 2. Carl Friedrichs von Weizäcker.

The MAUD committee recommendations were communicated to the USA’s

President Franklin D. Roosevelt in 1941. Although World War II had not yet started, the
discovery of nuclear fission ultimately led to the formation of the Manhattan District
Project, or the “Manhattan Project” in short, which became the USA government's secret
project to build a nuclear device.

2.3 ALSOS TEAM MISSIONS

In the last days before the end of World War II, undercover Allied special agents
engaged in a frantic race across Europe, sometimes competing against each other, to
capture the best and brightest of Germany's scientific community. With the German army
in retreat, American, British, and Russian forces set their sights on the architects of the so
called advanced Vengeance Weapons. These included high technology jet and rocket
airplanes, rockets, laboratory experiments, stockpiles of uranium in different forms and a
subcritical heavy water moderated assembly.
 Figure 3. The Leipzig subcritical assembly including a neutron source at its center with
heavy water (D2O, HDO) as a neutron moderator and natural uranium powder as a fuel.

Figure 4. Graphite blocks reflector surrounding an unfinished reactor core.

The reasoning behind the mission was that whoever captures the scientists, the
archives and the technology, was expected to gain a major scientific and technological
advantage in the looming Cold War. Another goal of the mission on the American side
was to deny this perceived advantage to the Russians as well as the French. This
assessment proved correct for the USA in the enticement of Werner von Braun and most
of his team in the establishment of its space and Intercontinental Ballistic Missile (ICBM)
Program.
The USA military launched the “Alsos” mission to search Germany not just for its
scientists like von Braun and Heisenberg and their teams, but also their experiments,
equipment and laboratories and any stockpiled strategic materials such as gold, silver,
copper and uranium. One such experiment was a subcritical assembly of natural uranium
powder and heavy water designated as the Leipzig experiment.
The mission consisted of undercover special agents and was led by Lieutenant
Colonel Boris T. Pash, and as scientific leader Sam Goudsmit. It was code-named “Alsos,”
the Greek word for “grove,” as in “tree grove” in honor of General Leslie R. Groves, the
head of the Manhattan Project. The mission followed immediately in the wake of, and
sometimes ahead of the allied armies invading Europe.
When the German scientists first discovered fission, the USA and the UK worried
that Germany could develop a nuclear device, and this was the main incentive for the
initiation of the MAUD committee in the UK and the Manhattan Project in the USA. Those
paranoid fears, based on overzealous and faulty intelligence, were totally dispelled just
weeks before the end of the war. The special agents of the American Alsos team discovered
a German subcritical assembly under construction in a cave beneath a castle at Haigerloch,
Germany, but no functional reactor. Intentionally, or unintentionally uninformed about the
residual radiation hazard, they promptly dismantled by hand the assembly which consisted
of wire-suspended natural uranium cubes in a heavy water moderator contained in a steel
vessel.

Figure 5. The Alsos team dismantling by hand the heavy water (D2O, HDO) subcritical
assembly at the village of Haigerloch, Germany.
 Figure 6. Retrieved buried uranium cubes by the Alsos team.

Figure 7. Diagram of the heavy water (D2O, HDO) natural uranium Berlin B8 and B1
subcritical assemblies.
Figure 8. Lid with wire-suspended natural uranium cubes pulled out from the heavy water
(D2O, HDO) moderator vessel of the Haigerloch, Germany subcritical assembly.

Figure 9. Museum at the Haigerloch site.

 Figure 10. Replica of German heavy water reactor at the Haigerloch Museum.

It was realized that he German nuclear scientists in 1945 were no farther along in
their nuclear program than the Americans had been back three years earlier in 1942.
With interrogation and enticements of the scientists, a few days later, buried in a
nearby field, the Alsos agents uncovered a cache of about two metric tonnes of natural
uranium. The mission also tracked down and secured amounts of uranium in different
chemical forms in France, Belgium, and Germany. This uranium was shipped to the
Manhattan Project for use in the American nuclear device effort.
A first mission code named “Alsos I” headed to Italy in December 1943, but gained
little information of interest, due in part to the slow progress of the Allies’ forces advance
towards Rome. A second mission designated as “Alsos II” followed the Allies’ forces
advance from France to Germany in 1944 and 1945. It consisted of seven military officers
and 22 scientists.
Interrogation of the French and German scientists combined with the searching of
laboratories, confirmed that the German program was never close to producing an atomic
device, let alone even achieving a self sustained critical chain reaction.

2.4 HEISENBERG’S LEADERSHIP OF THE GERMAN NUCLEAR

PROGRAM
Werner Heisenberg (1901–1976) is considered to have led the German nuclear
program during World War II. He is known for his formulation of the uncertainty principle
in quantum mechanics and its physical interpretation in 1927. He introduced the theoretical
insight that quantum mechanical variables do not commute.
 Figure 11. Werner Heisenberg, (1901-1976).

At 20 years of age, and well before the introduction of the concept of electron spin,
Werner Heisenberg made the proposal to allow half-integral quantum numbers in the
context of the Zeeman Effect. He was awarded the 1932 Nobel Prize “For the creation of
quantum mechanics, the application of which has led, among other things, to the discovery
of the allotropic forms of hydrogen.”
He provided the quantum-mechanical explanation of the occurrence of para-helium
and ortho-helium and provided an explanation for ferromagnetism. His most important
contribution is the foundation of the quantum field theory with Pauli. He became one of
the founders of theoretical nuclear physics with a description of the interactions between
protons and neutrons in a nucleus.
He went out of his way and used his influence to help his own students and
collaborators, both in peacetime and during the war, sometimes at risk to himself. Some
of them avoided death at the European and Russian fronts by being enlisted by Werner
Heisenberg in his nuclear research program. At one point he had to face treason
accusations by his political opponents as a “White Jew.” He was investigated and cleared
of the charges. From a totally opposite perspective, he was also accused of reaching a
Faustian pact with the devil for his refraining from emigration like many other German
scientists, and for participating in the German nuclear program.
He tried his best during the war in preventing the German forces from destroying
physics laboratories such as at the University of Leiden and of Bohr’s institute in
Copenhagen, Denmark. He implied that he steered the German nuclear program toward
nuclear energy and scientific applications and away from weaponization.

2.5 THE URANIUM CLUB, “URANVEREIN”

In September 1939, Werner Heisenberg was recruited into the German nuclear
research team known as “Uranverein” or “Uranium Club” by an order from the German
military. This team was assembled by Kurt Diebner, a competitor to Werner Heisenberg
on behalf of the Heereswaffenamt (HWA) or Army Ordnance Office.
 The formation of the Uranium Club followed suggestions by the physical chemist
and explosives expert Paul Harteck (1902–1985) and others that Germany should
investigate the possible relevance of nuclear energy to the war effort. Paul Harteck built a
single-stage ultra centrifuge experiment for the enrichment of uranium of scientific but of
no industrial relevance.

Figure 12. Paul Harteck built an experimental centrifuge.

Kurt Diebner (1905–1964) was an experimental physicist who played a central role
in the German nuclear project. During the war he was the principal scientific administrator
of the project, simultaneously holding the positions of military adviser to the HWA on
nuclear physics, director of the Nuclear Research Council or Kernforschungsrat, and
managing director of the Kaiser Wilhelm Institute for Physics. He ran his own subcritical
experiments, in direct competition with Werner Heisenberg. Kurt Diebner was a Nazi party
member, and was held in contempt by Werner Heisenberg, supposedly because he was an
experimentalist with ideas on experimental designs that were more successful than Werner
Heisenberg’s.
Werner Heisenberg obeyed an order from the German leadership and generated a
report on “The possibility of technical energy production from Uranium fission,” which
laid the theoretical foundations for the subsequent research in Germany on that topic. The
report correctly foresaw that a nuclear reactor could be built in two qualitatively different
ways, each posing its own challenges.
In the first approach one could use either use enriched uranium and an easily
obtained moderator such as ordinary water (H2O), or one could adopt natural uranium in
association with heavy water (D2O, HDO) or a highly pure graphite as a moderator.
Admittedly, Werner Heizenberg did in fact emphasize nuclear power production and not
weapons production.
The use of graphite as a moderator, which met with success in the USA program,
was not pursued in Germany due to a miscalculation in estimating its absorption cross
section to neutrons, and the German team had only two options left. Various isotopic
separation projects such as centrifuge enrichment, as well as a number of methods to
produce heavy water, were pursued, principally by Paul Harteck, just on a laboratory scale.

2.6 INTERNMENT AT FARM HALL, SOPHISTICATED BRITISH

INTERROGATION
The German nuclear research project was interrupted by heavy Allied bombings
and sabotage of Germany’s supply of heavy water from Norway. A subcritical moderated
assembly never achieved criticality all the way to the last days of the war.
Ten of the German nuclear physicists, including Werner Heisenberg were taken as
prisoners by the Allied Forces between May and December 1945. To sanitize their
detention, they were designated as “interns,” not as “detainees,” and kept during the last
six months of the war at a country estate, Farm Hall, near Cambridge in England.

Figure 13. Totally unworkable diagram of a gun barrel design for a plutonium device of
alleged German origin. The design is unachievable since plutonium requires an
implosion process to attain super-criticality. The diagram was possibly drawn by some
unknown individual after the war. Source: Nova.
 Figure 14. Die Glocke, the Bell, an alleged attempt at “torsional fields” to achieve
nuclear fusion was surrounded by secrecy.

Using a sophisticated, smart and effective way of harvesting information, the

British did not use the crude ineffective methods of torture, dogs, water-boarding, nor
sexual degradation and humiliation or coercion à la Abu Ghraib, Bagram Base and
Guantanamo Bay styles against them. In a sophisticated and smart interrogation fashion,
they treated them with the utmost respect and called them interns, instead of prisoners or
detainees. They nicely housed and generously dined and wined them.
However, their conversations were cleverly and secretly monitored and recorded
and were made public in 1992. At Farm Hall, the internees produced a carefully drafted
statement in their own defense whose main point was that: “It was the view of the
researchers that the resources for the production of a bomb were not available in the context
of the technical possibilities prevailing in Germany.” They seemed to be doubly hedging
their bets; so as not to be considered as traitors who effectively sabotaged the war effort by
the defeated Germans, and not as war criminals by the victorious Allies.
From the Farm Hall transcripts, Werner Heisenberg and his German colleagues
believed that their knowledge about nuclear technology and its possible military uses was
superior to that of the allied’s scientists. Their belief was shattered by the British
Broadcasting Corporation (BBC) News at 9 pm on August 6, 1945, announcing the nuclear
bombing of Hiroshima.
Werner Heisenberg suggested on various occasions in an ambiguous manner that
he had actually actively withheld the bomb from the German leaders. This line was
defended more vigorously by von Weizsäcker. Werner Heisenberg’s published writings on
the German nuclear project emphasized that its goal had been the: “Technical utilization
of atomic energy.” He stated that: “The project could not have succeeded under German
war conditions. To obtain the necessary support, the experts would have been obliged to
promise early results, knowing that these promises could not be kept. Faced with this
situation, the experts did not attempt to advocate with the supreme command a great
industrial effort for the production of atomic bombs.”
At Farm Hall, Werner Heisenberg said: “We would not have had the moral courage
to recommend to the government in the spring of 1942 that they should employ 120,000
men just to build that thing up.” He also admitted: “Well, how have they actually done it?
I find it is a disgrace if we, the professors who have worked on it, cannot at least work out
how they did it.”

2.7 EARLIER HYBRID FISSION-FUSION RESEARCH

Figure 15. Deuterium gas filled Crookes glow discharge tube with uranium metal foils
experiments in the 1920s.

In 1929, Walter Hernann Nernst (1864-1941), Nobel Laureate in Chemistry in

1920, remarked on experiments on hydrogen gas interaction with uranium metal in the
Zeitschrift magazine: “Hydrogen will dissolve into certain metals as if the metal was acting
like a dry sponge absorbing water.”
Glow-discharge experiments were conducted using Crookes tubes filled with
deuterium gas and uranium foils. These were precursors to the Farnsworth Fussier
experiments attempting the electrostatic fusion of deuterium in the 1960s. Niels Bohr
suggested that this approach could lead to the production of small nuclear devices instead
of the critical mass approach, which would be more suitable for large devices.
If deuterium is dissolved in heavy elements such as uranium or palladium metal
beyond a critical threshold concentration, an interaction between the deuterium and the
heavy metal was expected. It can be suggested that if it is a form of deuteron disintegration,
it becomes an avenue of energy release from the heavy metals without the need to reach a
critical mass of the fissile elements.

2.8 SAM GOUDSCHMIT AND WERNER HEISENBERG RIVALRY

Sam Goudschmit (1902-1978), was an emigrant scientist from Brookhaven
National Laboratory (BNL) in the USA who was assigned as a scientific head to the Alsos
project which was the scientific intelligence mission that followed the Allied troops in the
wake of their invasion of Europe. Its initial goal was to ‘”Learn as soon as we could what
the Germans might be able to do if they exerted every possible effort to produce an atomic
weapon.”
After it had become clear that nothing of substance was to be feared, its goal
evolved into keeping whatever scientists and scientific equipment that would be of any
military value out of the hands of the Russians and the French. Reporting directly to
General Leslie Groves in the USA, its military commander in Europe was Boris Pash, and
its scientific head was Sam Goudschmit.
A plea was made by Sam Goudschmit to Werner Heisenberg in 1943 for help in
saving his Jewish parents from deportation and almost certain death in a concentration
camp. Short of approaching Himmler this time or any German authority in Germany or
Holland, Werner Heisenberg merely sent a letter of support to Sam Goudschmit’s
colleague, Coster. As pointed out by Sam Goudschmit himself, it is doubtful that any
action by Werner Heisenberg would have been effective in his parents’ sad tragedy.
The internment of Werner Heisenberg and other German nuclear physicists at Farm
Hall in 1945 was part of the Alsos effort. A purpose of Farm Hall was to prepare the
German scientists for reintegration into the zones of Germany that, after the war, were
occupied by the UK and by the USA.
Sam Goudschmit wrote three popular articles and a book about the Alsos mission,
which served as a point of reference for later assessments of the German wartime nuclear
program. His conclusions were that the German nuclear project had not achieved even the
basics of understanding nuclear weapons, and that it had failed because of the totalitarian
climate in Germany, complacency, the interference of politicians in the affairs of science,
particularly of “utterly incompetent” key men in administrative positions, the deterioration
of interest in pure science and its lack of prestige, the anti-semitism doctrine of the Nazis
that led to the exile and migration of notable scientists, the lack of vision of the German
scientists, and, finally, because of the role of hero worship.
This specifically refers to Werner Heisenberg, who is portrayed by Sam Goudsmit
as holding competent research groups, such as those lead by Ardenne and Diebner, in
contempt. At the same time, Werner Heisenberg’s own erroneous judgments and
decisions, of which there were many according to Sam Goudschmit, were hardly openly
questioned by the other German researchers. Werner Heisenberg is portrayed as a man of
ideals, and as a fierce nationalist who had put his support for any German cause ahead of
his dislike of the Nazi Regime.
Werner Heisenberg seemed far more worried about accusations that he had not
understood bomb physics than about criticism of his general behavior during the Nazi era.
It appears that Werner Heisenberg did not understand how his courageous behavior during
the Nazi era, which he contrasted with the treason of emigration, could possibly be the
subject of controversy.

2.9 WERNER HEISENBERG AND NIELS BOHR MEETING

Werner Heisenberg met Niels Bohr in September of 1941. The accounts about that
meeting have been contradictory. Niels Bohr stated about the meeting that he remembers
quite clearly that Werner Heisenberg was confident that Germany would win the war, and
that Werner Heisenberg had made it clear to him that he was leading a German program to
develop atomic weapons, with whose details he claimed to be completely familiar. Niels
Bohr communicated this opinion to the UK and the USA, and this contributed to the
decision to initiate the Manhattan project.
From a contradictory perspective, von Weizsäcker responded about this statement
with: ‘‘Bohr’s memory is deeply mistaken.” He asserted that himself, Werner Heisenberg,
and other German scientists had already stopped their work on an atomic weapon in
September 1941, and that Werner Heisenberg had tried to persuade Niels Bohr that the
USA and the UK should not build atomic weapons either, an option Niels Bohr allegedly
refused to consider.
Niels Bohr agreed with Werner Heisenberg that no technical discussions took place,
and that Werner Heisenberg refrained from pumping Niels Bohr for information.

2.10 ERICH BAGGE AND DIEBNER ACCOUNT

Erich Bagge (1912) was a theoretical physicist who had written his thesis with
Werner Heisenberg, but who later became closely associated with Diebner, politically as
well as scientifically. He was a member of both the Nazi party and the Dozentenbund.
During his internment at Farm Hall, he kept a diary which was later turned into a book.
Erich Bagge and Diebner state their views on the German nuclear project claiming
that the crucial error was the Heereswaffenamt (HWA) or Army Ordnance Office,
requirement in December 1941 that something of immediate military use should emerge
from the nuclear research project within 9 months. Following the physicists’ clarification
that this would be impossible, the consequent transfer of authority from the HWA to the
Reichsforschungsrat (RFR) or National Research Council, and the appointment of the
technical physicist Abraham Esau as the man in charge, sealed the fate of a possible
German nuclear device, despite the fact that almost simultaneously the RFR was placed
under Goring’s supervision.
Esau was followed later by Speer as head of the RFR but had nothing to do with
these decisions since he became involved with the project only in the spring of 1942. There
is no mention by Erich Bagge and Diebner of Werner Heisenberg’s encounter with Speer
in June 1942, which according to Werner Heisenberg had been the pivotal meeting leading
to Speer’s, and not the HWA’s, decision to assign a relatively low profile to the German
nuclear project. This corresponds to Werner Heisenberg’s perception that he was the main
figure in the project and he possessed the power to influence the cardinal decision to step
up the project to industrial proportions.
Erich Bagge and Diebner maintained that Sam Goudsmit was incorrect in his
statements that the Germans had failed to recognize that a bomb could be made from
plutonium, a point that had earlier been made by Werner Heisenberg in correspondence
with Sam Goudsmit.
In their failed attempts to at least build a critical assembly, Erich Bagge and Diebner
blamed the repeated Allied attacks on the Norske Hydro factory at Rjukan, the main source
of heavy water (D2O, HDO) for the German project, for their failure. Rivalry and
disagreements about the subcritical assembly design between Werner Heisenberg’s group
and Diebner’s also led to failure.

2.11 THE VIRUS HOUSE

 In the book: “Virus House,” David Irving, a controversial British citizen author
wrote about the German nuclear project. He got himself employed as a factory worker in
Germany to perfect his mastery of the German language. This gave him access to the
German documents, literature and publications about World War II seized by the USA. He
used that capability to translate the documents and was able to publish several books about
various aspects of the Third Reich, some of which became best sellers.
Even though an Anglo Saxon, his books reflect the German perspective about
World War II. His first book describes the fire-storm bombing of Dresden. Another book:
“The Virus House,” was the first full study of the German Uranium project. It is based on
thousands of documents, many of which were unearthed by Irving himself, as well as on
interviews and correspondence with the main players.
The bombings, raids and sabotage of the Norske Hydro plant producing heavy
water for the German nuclear project are described in detail. Paul Harteck is placed at the
center stage instead of Werner Heisenberg. David Irving is of the opinion that the German
nuclear scientists failure to “Fire Speer’s imagination with the possibilities of nuclear
fission” as their greatest shortcoming. David Irving suggests that the German scientists
“Given the funds, the men, and the materials, could certainly have produced an atomic
bomb for Germany.”
David Irving blames the slow pace of the project on the fact that the project was
directed by scientists and not by the military, as in the USA: “In short, the behavior of the
German scientific leaders demonstrated that during war, science cannot be safely left to
scientists.” He blames its failure on the emphasis on theory with direct reference to Werner
Heisenberg, whom he implies intentionally sabotaged the project by slowing it down and
directing it toward unpromising directions.

Figure 15. Ultra centrifuge laboratory experimental setup by Paul Harteck and Groth.

Werner Heisenberg’s commented: “Irving’s book is a very good book in the sense
that it gives all the facts or practically all the facts. But it has one deficiency. When he
tries to determine motives he does not do very well because he cannot think himself into
the atmosphere of a totalitarian country making war.”
 David Irving follows Werner Heisenberg’s version of the events, such as in his
emphasis on incorrect measurements by Bothe of the graphite nuclear properties. The
measurements were in impure graphite leading to a large absorption cross section for
neutrons, which precluded its use as a moderator instead of heavy water in the German
program, whilst it was used in the USA program. He describes the subsequent decision to
continue with heavy water as a moderator. He sides with Werner Heisenberg’s claims
against those of Sam Goudsmit, that he had fully understood the principles of the atomic
bomb.
David Irving discards the suggestion by many German scientists that they did not
pursue the bomb because they did not want it on moral principles. He wrote that: “There
is no indication that at any stage in the logical process of development the scientists’
scruples would have become powerful enough to overcome their natural curiosity to see
what came next.”

2.12 WERNER HEISENBERG’S PERSPECTIVE

In his autobiography: “Der Teil und das Ganze” or “Physics and Beyond,” Werner
Heisenberg relates conversations between himself and some of his friends on the principal
themes that occupied his mind. He states that he saw National Socialism as a catastrophe
right from the beginning, which could only lead to the destruction of Germany. He relates
a conversation in 1939 with Enrico Fermi, Sam Goudsmit, and other colleagues in the USA,
in which he expressed no doubt whatsoever that Germany would lose the upcoming war.
Werner Heisenberg maintains that the German physicists had fully understood
applied nuclear physics with regard to both reactors and weapons. Werner Heisenberg
denies the fact that the German scientists basically told their military all they knew, even
about fast neutrons. This implies that a German nuclear device was never built because
the German politicians and military officials, based on information provided by their
scientists, decided that it would not be possible before the end of the war, and allocated
their limited resources to what they perceived as more promising concepts such as military
airplanes and rockets.
Werner Heisenberg saw himself as the originator of the decision not to proceed in
the direction of building a weapon which he subsequently placed it in the hands of Speer.

2.13 WERNER VON HEISENBERG’S MISCALCULATION

In the book: “Heisenberg and the Nazi Atomic Bomb Project: A Study in German
Culture,” P. L. Rose advances a thesis about the German nuclear project that was repeated
a number of times.
He suggests that in 1940 Heisenberg incorrectly estimated or calculated the critical
mass of a pure U235 device, obtaining an answer in the order of tons or thousands of
kilograms, instead of the correct value of 15-56 kgs; depending on whether the assembly
was bare or had a reflector/tamper as shown in Table 1.
His mistake was based on the misconception that a nuclear explosive reaction
would only occur by creating a supercritical condition in a moderated assembly such as
what he built with heavy water and natural uranium, instead of a fast assembly consisting
of separated metallic U235 or Pu239.
 Table 1. Critical masses in kilograms of bare and reflected U235 and Pu239 cores.

U235 Pu239
Bare unreflected core 56 11
Core with an infinite U 15 5
Reflector / Tamper

This may have precluded him from recommending a serious effort on the atomic
weapons problem. Rose suggests that this was the true reason why Germany failed to
achieve the bomb, and it was a situation that the Werner Heisenberg version of events tried
to conceal.
Rose’s conclusion is that the explanation must be “Grounded in the peculiarities of
the German mentality,” in particular in the “German capacity for self-delusion, a trait
exemplified to an astonishing degree in Heisenberg himself.”
Rose confirms what Sam Goudsmit had said that as far as nuclear devices were
concerned, the German scientists never got beyond some very basic insights and had not
done any relevant experimentation. He concludes that the Germans knew that natural
uranium was not suitable for a weapon, that one had to use either almost pure U235 or some
higher transuranic element such as plutonium or neptunium, and that fission by fast
neutrons should cause the explosion as opposed to the case of thermal neutrons in a
moderated reactor.
However, they had not measured any of the relevant reaction cross-sections, had
not isolated neither U235 nor Pu239 and had not considered how subcritical lumps should be
brought together to initiate an explosion.
Rose exposes in detail an initial and erroneous Farm Hall argument made by
Werner Heisenberg that led to an estimation of a critical mass of a uranium device in the
order of tons instead of the kilograms level.
At Farm Hall, Werner Heisenberg arrived at a realistic value for the critical mass
only in his lecture on August 14, 1945. Rose projects Werner Heisenberg’s initial Farm
Hall calculation back to 1940, to conclude that the Germans thought throughout the war
that the critical mass of a U235 device was of the order of tons. Werner Heisenberg
presented his earlier incorrect Farm Hall calculation without much thought, whereas his
later correct argument was arrived at only after a week of intense thinking.
During the war, and certainly in 1942, the Germans did work with a perceived
critical mass of 10–100 kg in the 1942 HWA report: “Energiegewinnung aus Uran.”
Werner Heisenberg’s made a famous remark about the volume of an atomic weapon being
of the size of a “pineapple” in June 1942.
Rose suggests that the 10–100 kgs must refer to plutonium. The 10–100 kgs seems
a rough estimate, whose origin is unknown. Even if by chance the German scientists got
the value of the critical mass roughly right, they had not nearly arrived at the correct
reasoning leading to this value.
On the USA’s side, this reasoning started with the work of Frisch and Peierls in
England in March and April 1940. Even Enrico Fermi’s estimates of the critical mass were
initially wrong by orders of magnitude.
 Rose gives an interesting account of various ideas on “reactor bombs,” showing
that at a certain stage Werner Heisenberg saw a nuclear device as an extreme type of a
nuclear reactor, with highly enriched uranium and large quantities of moderator that went
supercritical. This idea was subsequently pursued by some of Werner Heisenberg’s
associates. Werner Heisenberg did in fact study in detail the self-stabilization by the
negative temperature coefficient of reactivity of ordinary nuclear reactors at high
temperature.
Rose maintains that Werner Heisenberg was basically incompetent in spite of his
established genius as a theoretical physicist. After all, weapons design is in essence an
engineering problem, and Werner Heisenberg was neither an experimental physicist nor an
engineer.

Figure 16. Norsk Hydro plant at Vemork, Norway was source of D2O for German
program.

Figure 17. Ferry carrying shipment of D2O barrels was sunk in February 1943 by UK
sabotage and Norwegian resistance group with Norwegian passengers.

2.14 CAUSES OF FAILURE AND SUCCESS

Werner Heisenberg was an excellent theoretical physicist, but not a skillful project
manager, an experimentalist nor an engineer. He was the wrong choice for leading the
German nuclear program. He did not know how to correctly compute the critical mass of
a nuclear device, and was not able to generate its outline. Werner Heisenberg’s lack of
leadership has been suggested as the main cause behind the failure of the German nuclear
program. The significant lead time that Germany initially possessed, by the discovery of
nuclear fission on its soil, was promptly lost.
The “hero worship” alluded to by Sam Goudsmit, worked against other members
of the Uranium Club correcting Werner Heisenberg’s faulty calculations and ideas. In
addition, Werner Heisenberg’s intensely competitive spirit and egocentrism led him to
control much of the uranium and heavy water that the Germans possessed for his own
experiments, even at times denying a fair share of them to Paul Harteck and Diebner; both
of whose experiments were generally more promising and superior to Werner Heisenberg’s
ones.
In comparison, one can surmise that the USA’s Manhattan Project successfully
reached its goal, albeit after the surrender of Germany, because of the following reasons:

1. There was a strong initial drive by a dedicated group of scientists and physicists to get
the project started. Key figures such as Albert Einstein lent their support with a letter to
the USA President.
2. There was unconditional support from the USA and UK governments and adoption by
the leadership and by the USA president.
3. The top management of the project was assigned to the military and engineers, and not
just the envious and competing scientists, in the person of Brigadier General Leslie Groves,
from the USA Corps of Engineers who had earlier built the Pentagon structure. These have
the resources and technical experience to carry an armament project to its ultimate success.
4. Unlimited industrial resources such as from the DuPont Company and manpower were
made available to the project in the USA.
5. There was an unprecedented concentration of brilliant and dedicated scientists working
on the project under the leadership of Robert Oppenheimer at the Los Alamos National
Laboratory, LANL.

In contrast, the German scientists did not trust, held in contempt, and in some cases
despised their government officials; and vice versa. From the Farm Hall transcripts it is
clear that some of the German scientists, including Werner Heisenberg, were afraid of
ending up in a concentration camp in case they would start a project and then fail in
achieving its stated goals.
Whether or not he was aware of the concept of a critical fast spectrum mass during
the war, Werner Heisenberg correctly foresaw the massive industrial scale at which
isotopic separation and heavy water production would have had to take place. In the early
years of the war, when Germany seemed to be on the winning side, such an industrial effort
might have been possible, but it was seen to be unnecessary to win the war. In later years
with the tide turning against Germany, the resources and human power were not available,
and the task became impossible to achieve.
Overconfidence and arrogance, racism and religious fanaticism led to the
emigration or expulsion of both non-Jewish and Jewish prominent scientists such as
Shrödinger, leaving Germany with a reduced limited scientific base.
 Werner Heisenberg and von Weizsäcker saw an open road to an atomic bomb based
on the extraction of plutonium from a heavy water nuclear reactor burning natural uranium,
but they were unaware of the monumental technological difficulties of actually extracting
and separating this plutonium.
It was mentioned that von Weizäcker was mistaken in considering neptunium239
rather than plutonium239 or neptunium237 as possible weapon materials. Even if they had
obtained them, they had no idea of the difficulties of bringing a plutonium bomb to super-
criticality by the implosion process.
Some historians contend that Werner Heisenberg and his colleagues in wartime
Germany had only a shallow understanding of the physics and technology of nuclear
devices. This agrees with the conclusion of Allied intelligence work during and after the
war. Werner Heisenberg and some of his colleagues were in no position to claim that
during the war they had known how to build a nuclear device, let alone that they had
refrained from doing so for moral reasons, as some of them conveniently claimed after the
war.

2.15 DISCUSSION
There has been an unsubstantiated rumor that during the last months of the war, a
small group of scientists working in secret under Diebner and with the support of the
physicist Walther Gerlach, who became head of the uranium project, tried to build and
tested a nuclear device. The allegation is that the German scientists run an unsuccessful
test using chemical high explosives configured in a hollow shell in an attempt at initiating
both nuclear fission and nuclear fusion reactions.
A great irony is that the German scientists, their politicians and their military
apparently never tried nor realized the practical and industrial possibility of building a
nuclear device, and concentrated their efforts on the pure scientific goal of achieving a self-
sustained chain reaction. Werner Heisenberg apparently never took the possibility of
building a nuclear device seriously and hardly tried. He was aware of the possibility of
achieving criticality in a thermal-neutron moderated assembly, but not in a fast-neutron
spectrum assembly. He expended a substantial effort to achieve criticality in a moderated
subcritical assembly to impress the Allies in future peace time, thereby hoping to secure
Germany’s physics and his own personal leading role in it. Through rivalry and
misconception he hindered the effort of other German scientists such as Diebner.
Another irony was that the atomic bomb developed by the USA and meant to be
used against Germany, could not be used against it any more after its surrender, and was
targeted instead against Japan. Yet another irony is that Germany’s dominance over Europe
repeatedly failed through military means, but subtly succeeded within the economic realm
of the European Union (EU). With a powerful manufacturing base and a vast export
capability, Germany follows the example of the British Empire in dominating its previous
colonies through economic and political means, rather than by military means. This is
achieved by holding and controlling the sovereign and private debt of the European GIIPS
quintet of economically depressed countries of Greece, Ireland, Italy, Portugal, and Spain;
as well as France.

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