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Nazi nuclear research: Why didn’t Hitler get the Bomb? Jim Thomson

www.safetyinengineering.com 1 Nazi nuclear research

1. The German project and a brief comparison with the Manhattan and V-weapons projects 2. German project technical achievements and failures 3. Political and organisational factors 4. Motives, ethics, competence and honesty 5. Postscript: The lunatic fringes

2 Jim Thomson www.safetyinengineering.com 1. The German project and a brief comparison with the Manhattan and V-weapons projects 3 Jim Thomson www.safetyinengineering.com Arnold Kramish 1985 The Griffin 1947: April 1943: “Los ALSOS – Samuel Mark Walker 1989 German National Socialism and the Quest Dec 1942: for 1939–1949 Alamos Primer” Goudsmit Chicago pile UK Government 1992 Farm Hall transcripts declassified lecture notes give (republished 1996) critical complete overview of David Cassidy 1992 : The Life and of bomb project Frisch-Peierls 1944/1945: ALSOS 1956: Thomas Powers 1993 Heisenberg’s War memorandum mission to capture Brighter Than a Mark Walker 1995 Nazi Science: Myth, Truth, and the German March 1940 German researchers , Thousand Suns – Atomic Bomb July/Aug 1945: Einstein letter equipment and data Paul Lawrence 1998 Heisenberg and the Nazi Atomic Bomb to Roosevelt , and Rose Project: A Study in German Culture . The Smyth 1968: 2000 ‘The German Project’, Article in August 1939 Today Report outlines the The Virus House - 2001 Hitler's Uranium Club: The Secret David Irving and David Cassidy Recordings at Farm Hall 1930s 1940s 1950s 1960s 1970s 1980s 1990s 2000s

March 1945: Discovery B-VIII pile at of fission fails to go critical FirstGermany German government 1938/39 1943: 1947: interest April plant Heisenberg 1939 publishes his First sub- May/:destroyed L-IV pile shows account in critical pile, Ongoing efforts multiplication, Autumn at enrichment 1940 then destroyed in February 1942: Presentationhydrogen explosion to senior GovernmentMay-Dec 1945:officials. Ten Despite suggesting “bombs the size of pineapples”, the nuclearmembers project is ofjudged team not to help war effort on the necessary timescale and is thereforeinterned downgraded at Farm in importance. Responsibility moved from Army OrdnanceHall, Cambridgeto Reich Research Council 4 Jim Thomson www.safetyinengineering.com Why were the Allies so worried about the ? For example: • Heisenberg: 1932 for quantum and the ‘’. Refused offer to move to USA in summer 1939 (when he visited Goudsmit in USA). • von Weizsäcker: with extremely good political connections; pupil of Heisenberg. • Hahn: Discoverer of fission 1938. Worked with Fritz Haber on poison gas during WW1. Discovered Protoactinium 1921. • Clusius: First person (1939) to separate the two naturally- occurring of chlorine Cl-35 and Cl-36.

5 Jim Thomson www.safetyinengineering.com Einstein’s letter to President Roosevelt, 2 August 1939 (drafted by ) “I understand that has actually stopped the sale of uranium from the Czechoslovakian mines which she has taken over. That she should have taken such early action might perhaps be understood on the ground that the son of the German Under-Secretary of State, von Weizsacker, is attached to the Kaiser Wilhelm Institute in , where some of the American work on uranium is now being repeated.”

6 Jim Thomson www.safetyinengineering.com Extracts from the Frisch-Peierls memorandum, UK, March 1940 (written before anyone really knew the scale of the effort needed) “...... it is quite conceivable that Germany is, in fact, developing this weapon. Whether this is the case is difficult to find out, since the plant for the separation of isotopes need not be of such a size as to attract attention. Information that could be helpful in this respect would be data about the exploitation of the uranium mines under German control (mainly in ) and about any recent German purchases of uranium abroad. It is likely that the plant would be controlled by Dr. K. Clusius (Professor of Physical in University), the inventor of the best method for separating isotopes, and therefore information as to his whereabouts and status might also give an important clue...... “Since the separation of the necessary amount of uranium is, in the most favourable circumstances, a matter of several months, it would obviously be too late to start production when such a bomb is known to be in the hands of Germany, and the matter seems, therefore, very urgent...... “For the separation of the uranium 235, the method of thermal diffusion, developed by Clusius and others, seems to be the only one which can cope with the large amounts required.” 7 Jim Thomson www.safetyinengineering.com The view from Soviet in 1940 Georgi Flerov (Soviet physicist who worked on the Soviet weapons programme and who also discovered in 1940 the of uranium):

“It seemed to us that if someone could make a nuclear bomb, it would be neither the Americans, English or French but Germans. The Germans had brilliant chemistry; they had technology for the production of metallic uranium; they were involved in experiments on the centrifugal separation of uranium isotopes. And, finally, the Germans possessed heavy water and reserves of uranium. Our first impression was that Germans were capable of making the thing. It was obvious what the consequences would be if they succeeded.”

8 Jim Thomson www.safetyinengineering.com Some key German scientists

Werner Walter Bothe Heisenberg 1879-1968 1902-1985 1889-1979 1891-1957 1901-1976

Carl-Friedrich Carl Wirtz von Weizsäcker 1910-1994 1905-1964 1912-1996 1903-1963 1912-2007

9 Jim Thomson www.safetyinengineering.com Erich Bagge Developed a uranium enrichment device in 1944. Nazi Party member. 1912-1996 Prisoner at Farm Hall 1945. Theoretical physicist. Nobel Prize 1954 for study of wave-particle duality. An important member of the German nuclear project, his 1891-1957 measurements led to the conclusion that graphite was not a suitable moderator, probably due to boron contamination. Klaus Clusius In 1939 he achieved the separation of the natural chlorine isotopes. During WW2, he worked on separation and heavy water 1903-1963 production. University 1947 to 1963. Kurt Diebner Overall manager of the German nuclear project. After WW2, worked with Bagge on marine applications of nuclear power. Nazi Party member. 1905-1964 Prisoner at Farm Hall 1945. Developed Geiger counter. Geiger-Marsden experiment (1909) discovered . Enigmatic, he expressed no views about . 1882-1945 Walter Gerlach In 1921 he discovered quantisation in a magnetic (the Stern-Gerlach effect). Head of Physics in the Reichforshungsrat (Reich Research 1889-1979 Council) 1944-1945. University of Munich 1948-1957. Prisoner at Farm Hall 1945. Otto Hahn With , discovered Protoactinium 1921. Director of the Kaiser Wilhelm Institute for Chemistry 1928 to 1946. With his student Fritz 1879-1968 Strassman, and also Lise Meitner and Otto Frisch, he discovered fission in 1938. An opponent of Jewish persecution in , he did not contribute to the wartime nuclear research programme. Nobel Prize 1944. Prisoner at Farm Hall 1945. Paul Harteck Alerted the Herreswaffenamt (Army Weapons Office) in April 1939 about the possible military applications of nuclear research. Did work on 1902-1985 uranium and heavy water production. Developed a prototype centrifuge for isotope separation. Rensselaer Polytechnic Institute, , 1955 to 1968. Prisoner at Farm Hall 1945. Werner Heisenberg Key founder of . Nobel Prize 1932. Technical leader of the German wartime nuclear research programmes. After WW2, he 1901-1976 was involved in the first German at Karlruhe. Director of the Kaiser Wilhelm Institute for Physics (KWIP) (later re-named the Institute for Physics). Prisoner at Farm Hall 1945. Theoretical physicist, one of the founders of quantum mechanics. Nazi Party member. 1902-1980 A colleague of , he worked on isotope separation during WW2. Prisoner at Farm Hall 1945. 1912-1998

Max von Laue Discovered of X-rays by crystals. Nobel Prize 1914. A strong anti-Nazi, he took no part in the wartime nuclear research programme. www.safetyinengineering.com Thomson Jim 1879-1960 A prisoner at Farm Hall 1945, this may have been to stop the Soviets capturing him. Karl Wirtz Scientist at KWIP who worked on reactor design. University of Gottingen 1948 to 1957. Technische Hochschule 1957 to 1979. 1910-1994 Prisoner at Farm Hall 1945. Carl Friedrich von His father was a State Secretary at German Foreign Office from 1938 to 1943. His brother Richard later became President of Germany 1984 to Weizsacker 1994. His grandfather had been Prime Minister of Wurttemburg. He studied under Heisenberg and . He was involved throughout 1912-2007 WW2 in the German nuclear programme. In 1941 he filed a patent for nuclear bombs. Max Planck Institute for Physics, Gottingen, 1946 to 1957. University of 1957 to 1969. Became a Christian pacifist. Prisoner at Farm Hall 1945. Manfred Ardenne Early television pioneer. Worked on and nuclear research during WW2. Worked on Soviet A-bomb programme after WW2. Worked with 1907-1997 Fritz Houtermans (1903-1966).

Robert Dopel Experimental nuclear physicist, worked for Heisenberg on design of spherical sub-critical assemblies at . Worked on Soviet A-bomb Some notable German nuclear scientists whostayed in Germany 1895-1992 programme after WW2. 10 Siegfried Flugge Theoretical physicist. Worked with Weizsacker. Post-war, he edited the 54 volume Encyclopaedia of Physics. 1912-1997 Some notable exiles from Nazi mainland Europe

Hans Bethe Half Jewish German physicist, moved to UK 1933 then USA 1935. Stellar 1906-2005 theory (C-O-N cycle). Head of Theoretical Division in Los Alamos. Bethe-Tait analysis for fast reactor accidents. Nobel prize 1967. Niels Bohr Standard model of . ‘ interpretation’ of quantum 1885-1962 mechanics. Half-Jewish. Escaped from Copenhagen in 1943. Nobel prize 1922 Joint founder of quantum mechanics. Moved to Britain 1939. Nobel prize 1882-1970 1954. Italian theoretical physicist (wife Jewish), moved to USA 1938. Led team that 1901-1954 built Chicago pile, 1942. Nobel Prize 1938. Moved to USA 1933. Nobel prize 1921. 1879-1955 Otto Frisch Co-discoverer of fission. Frisch-Peierls memo, March 1940. Nephew of Lise 1904-1979 Meitner. Non-Jewish Communist party member who fled to UK after Reichstag fire. 1911-1988 Los Alamos – design of Fat Man 1944-1945. Harwell head of . Russian spy, convicted 1950 – gave Soviets details of bomb design. Lise Meitner Co-discoverer of fission, emigrated to where she stayed throughout 1878-1968 WW2. Amazing all-round genius. Game theory, computers, Monte Carlo method. 1903-1957 Jewish paternal grandparents. Pauli exclusion principle. Moved to US 1940. 1900-1958 Nobel prize 1945 Frisch-Peierls memo, March 1940.Manhattan project. Major role in UK 1907-1995 nuclear programme. Emilio Segre Jewish Italian physicist, moved to USA 1937. Discovered technetium, astatine 1905-1989 and the antiproton. Head of Radioactivity Group, Los Alamos. Nobel prize 1959. Leo Szilard Drafted the letter to Roosevelt for Einstein. Another amazing all-round 1898-1964 genius. Knew how to make boron-free graphite. Technical lead on H-bomb development, alleged basis for ‘Dr Strangelove’. 1908-2003 Hungarian Jew who emigrated to USA 1935. Co-inventer with von Neumann of the Monte Carlo method. Helped Teller 1909-1984 with the design of the H-bomb.

11 Jim Thomson www.safetyinengineering.com V-1/V-2 vs Manhattan – project comparison Source: Wikipedia • Beginning in September 1944, 3,225 V-2s were launched, mostly at London and later and Liège. The attacks resulted in the deaths of an estimated 9,000 civilians and military personnel, while 12,000 forced labourers and concentration camp prisoners were killed producing the weapons – i.e. the V2 killed more in its production than its deployment.

• The German V-weapons (V-1 and V-2) cost $3 billion (wartime dollars) and were more costly than the Manhattan Project that produced the atomic bomb ($1.9 billion). 6,048 V-2s were built, at a cost of approximately 100,000 Reichmarks (GB£2,370,000 (2011)) each.

• SS General Hans Kammler, who as an engineer had constructed several concentration camps including Auschwitz, had a reputation for brutality and had originated the idea of using concentration camp prisoners as slave labourers in the rocket program. (Kammler is believed to have been killed in May 1945, but this is disputed.)

• CONCLUSION: A Manhattan-scale project would have been possible in Nazi Germany, if the political will had been behind it. 12 Jim Thomson www.safetyinengineering.com Scale of German atomic project vs Manhattan project

• Manhattan project: cost ~ $2 billion (1945) – Staffing levels ~ 120000 maximum

• German project: cost ~ $2 million(1945) – Staffing levels ~70 scientists

13 Jim Thomson www.safetyinengineering.com Manhattan project vs German project - overview Process Manhattan project achievements during German project WW2 1 Electromagnetic Oak Ridge, Tennessee, Y-12 No separation ‘’ up to 84% U-235

2 Gas diffusion Oak Ridge K-25 No separation Used to take enrichment from 2% to 23%

3 Thermal diffusion Oak Ridge S-50 Experimental only, Used to enrich up to 2% unsuccessful 4 Gas centrifuges – Experimental only Experimental only, 1-2% U- separation of U-235 235 achieved early 1945 5 Heavy water Trail, British Columbia (from 1943) Vemork, , from mid- production 1930s 6 Uranium-graphite Hanford, Washington 250 MWth piles for No reactors production (also the CP-1 pile in Chicago and the X-10 pile at Oak Ridge) 7 Uranium-heavy water CP-3, Argonne, Chicago B-VIII, Haigerloch, March reactors (critical 15th May 1944) 1945 (but subcritical) 8 Plutonium separation Hanford ‘canyons’ No

9 Weapon design and Los Alamos, New Mexico No assembly

14 Jim Thomson www.safetyinengineering.com 2. German project technical achievements and failures

15 Jim Thomson www.safetyinengineering.com Organisation (approximate)

Goering/Speer

Schumann (until 1942), Herreswaffenamt HWA Esau (1942-1944), RFR Gerlach (1944-1945), Reichsforschungsrat

Heisenberg Harteck Bothe KWIP Berlin Hamburg KWIM Berlin Theoretical physics Isotope separation Nuclear properties Subcritical assemblies

Hahn Diebner Clusius KWIC Berlin Gottow Munich Nuclear chemistry Theoretical physics Isotope separation Subcritical assemblies

16 Jim Thomson www.safetyinengineering.com The L-IV pile, Leipzig, 1942

The photo probably shows the similar-looking B-III pile which had horizontal layers of uranium metal and paraffin wax.

The L-IV pile gave the first evidence of neutron multiplication in May 1942. It was destroyed in a explosion in June 1942. 17 Jim Thomson www.safetyinengineering.com The B-VIII pile, Haigerloch, 1945

• Criticality was attempted 24th March 1945. • Neutron multiplication, “Die maschine geht!”, but no criticality • No control rods! 18 Jim Thomson www.safetyinengineering.com 1500 kg heavy water B-VIII pile, Haigerloch >1500 kg U metal cubes 10000 kg graphite 500 mg radium-beryllium

19 Jim Thomson www.safetyinengineering.com B-VIII museum model

20 Jim Thomson www.safetyinengineering.com B-VIII neutronics analysis, 2009

“...... the B-VIII reactor was not too far from being a good working critical reactor.”

Keff = 0.89 approx

21 Jim Thomson www.safetyinengineering.com ALSOS team recovering uranium metal cubes buried by the Germans, Haigerloch 1945

The followed the Allied forces into Europe to try to find out whether the German Bomb project was a real threat. By Dec 1944, they knew there was no real threat.

22 Jim Thomson www.safetyinengineering.com Uranium cubes from Haigerloch

23 Jim Thomson www.safetyinengineering.com Key mistakes and decisions- 1 • “Graphite is unsuitable as a moderator”, (Walther Bothe, 1940) probably due to boron contamination at the ppm level. • (In the Manhattan project, Leo Szilard knew that the normal route for manufacturing graphite involved boron carbide electrodes. Hence he got the manufacturers to change the electrode material.) • Hence the Germans were tied to using heavy water, but shortages meant this could only be done at the Vemork hydro plant in Norway. • The Vemork plant was attacked twice in 1943 by Commandos and then by Norwegian partisans, which put it out of action for the rest of the war (as in the film ‘The Heroes of Telemark’) • RESULT: The Germans never produced enough heavy water to make an operating reactor (but see Postscript??) 24 Jim Thomson www.safetyinengineering.com The Vemork plant and its destruction

Vemork Hydroelectric Plant at , Norway in 1935. In the front building, the hydrogen production plant, a Norwegian Special Operations Executive (SOE) team (Operation Gunnerside) blew up heavy water production cells on 27 February 1943.This operation effectively ended heavy water production within the Greater Reich.

The Germans acquired about 2655kg from Vemork in total.

Part of the electrolysis plant, now in the Resistance Museum in Oslo

25 Jim Thomson www.safetyinengineering.com The importance of the destruction of the heavy water plant • “...... the elimination of German heavy water production in Norway was the main factor in our failure to achieve a self- sustaining atomic reactor before the war ended.” Kurt Diebner

26 Key mistakes and decisions - 2

• No serious effort at large-scale enrichment was made. • This was because i. The size of the plant would have been prohibitive (huge power consumption, it would have been a target for bombing, huge effort would have been needed) ii. Heisenberg over-estimated the necessary amount of U-235 for a bomb

27 Jim Thomson www.safetyinengineering.com Enrichment: lab-scale efforts

The Clusius-Dickel tube had worked for chlorine isotope separation, but it could not be made to work effectively with uranium hexafluoride.

28 Jim Thomson www.safetyinengineering.com Enrichment: Experimental centrifuge

Early 1945: Centrifuges were finally in operation at Celle, 2.5 hours by train from Hamburg.

By late Spring 1945, they were producing 50 gms per day of uranium with “15 percent more U235 than normal”.

29 Jim Thomson www.safetyinengineering.com Enrichment - outcome

“In comparing the progress with the centrifugal method of separation made by the Germans and by ourselves it is clear that at the end of the war they were far behind where we were in this country at the end of 1943…………” From US report, 1946

30 Jim Thomson www.safetyinengineering.com Key mistakes and decisions - 3 • There was a belief that the nuclear project could not yield any benefit to the war effort before the war was over. • This was correct in hindsight – even the Manhattan project did not deliver until after the European war was over. • In 1941, when the Germans might have begun a major effort on nuclear weapons, the war seemed already won. • By 1943/44, the Allied bombing made any major effort very difficult.

31 Jim Thomson www.safetyinengineering.com Allied bombing

• In 1943/44, the laboratories in Hamburg, Leipzig and Berlin all suffered severe disruption because of bombing. • Developments slowed. In 1944, the nearly- completed B-VII reactor was disassembled and moved to Haigerloch (where it became B-VIII).

32 Jim Thomson www.safetyinengineering.com 3. Political and organisational factors

33 Jim Thomson www.safetyinengineering.com vs Jűdische Physik • Phillipp Lenard and were old Nobel- winning classical who had been left behind by relativity and quantum physics. • They were both early Nazi party members. • In the 1930s, they used their positions to criticise as ‘Jewish’ and ‘non-Aryan’. • Heisenberg was described (1934) as a ‘white Jew’. • Heisenberg appealed to Himmler who eventually (1937) supported him. This issue was then put to rest – but there were possibly lingering doubts.

34 Jim Thomson www.safetyinengineering.com The ‘Coming-out Party’, Feb 1942 (and further meeting with Speer/Milch in June 1942)

A seminar to present the results of basic research to political and military leaders

Geheim = Secret

1. as a weapon 2. The fission of uranium nuclei 3. The theoretical basis for energy production from uranium fission 4. Results of experimental arrangements so far on energy production 5. The need for further basic research 6. Enrichment of uranium 7. Production of heavy water 8. The expansion of the nuclear physics project

Heisenberg, “A bomb the size of a pineapple could destroy a city...... ”

35 Jim Thomson www.safetyinengineering.com Loss of focus • Heisenberg published a book about cosmic rays in 1943. Others were doing non-project-related work also. • Heisenberg and others spent a lot of time in 1943/44 acting as ‘cultural ambassadors’, giving lectures within Europe. • Heisenberg visited Holland, Switzerland, Czechoslovakia, and . • Heisenberg visited Poland at the invitation of Hans Frank, Governor General, who was an old school friend. • (Frank was executed at Nuremberg. ‘‘What we recognize in Poland to be the elite must be liquidated.’’ Poland, he said, was to ‘‘become a society of peasants and workers’’ with no ‘‘cultured class.’’ As far as Poles were concerned, higher education as well as Polish theatre and literature was to cease. The language itself was to be obliterated. Heisenberg in Poland, J Bernstein, Am J Phys, 72 (3) 2004)

36 Jim Thomson www.safetyinengineering.com The ‘Railway Switchyard’

37 Jim Thomson www.safetyinengineering.com 4. Motives, ethics, competence and honesty

38 Jim Thomson www.safetyinengineering.com Why did the project fail? - 1

The Jungk/von Weizsäcker/ Heisenberg/Powers version: I. “We only wanted to make a uranmaschine.” II. We procrastinated to ensure Hitler didn’t get the bomb (German scientists as heroes) III. But....we could have made a bomb if we had wanted to (i.e. We didn’t screw up) IV. And.... we lacked the moral courage to recommend a project requiring 120000 people. 39 Jim Thomson www.safetyinengineering.com The Jungk/von Weizsäcker/ Heisenberg/Powers version Robert Jungk, Brighter than a Thousand Suns, (Heller als Tausend Sonnen), 1956: “It seems paradoxical that German nuclear physicists, living under a sabre-rattling dictatorship, obeyed the voice of conscience and attempted to prevent the construction of atomic bombs, while their professional colleagues in the democracies, who had no fear, with very few exceptions concentrated their whole energies on the production of the new weapon.”

Arnold Kramish, The Griffin, 1986: “Jungk’s book was an early example of the shameful fiction that has now been taken as gospel.”

40 Jim Thomson www.safetyinengineering.com Jungk recants (1990)

“That I have contributed to the spreading of the myth of passive resistance by the most important Nazi physicists is due above all to my esteem for these impressive personalities, which I have since realised to be out of place.”

41 Jim Thomson www.safetyinengineering.com Heisenberg’s visit to Bohr in Copenhagen, September 1941 (’s play ‘Copenhagen’) • Bohr’s version: Heisenberg told him that (a) Germany had won, (b) Germany was developing nuclear weapons, (c) Did Bohr want to help?

• Heisenberg’s version: (a) He feared the Allies were developing nuclear weapons, (b) He wanted to spare Germany the consequences, (c) He wanted Bohr to get a message to the Allies to say that Germany was nowhere near producing nuclear weapons.

• We will never really know what passed between them. • They knew each other very well. Each spoke the other’s language well. • Either (i) one of them lied, or (ii) they just misunderstood each other. • Did Bohr have any motive to tell a lie? 42 Jim Thomson www.safetyinengineering.com Letter from Lise Meitner to , June 1945

“One should force a man like Heisenberg and many millions like him to go to these camps and see the martyred victims. His visit to in 1941 is unforgivable.”

(quoted in Kramish)

43 Jim Thomson www.safetyinengineering.com Copenhagen – Recent developments • Unsent draft letters from Bohr to Heisenberg dated 1958 were published in 2002, which showed that Bohr remained extremely annoyed with Heisenberg for allowing Jungk (“Brighter than a Thousand Suns”) to repeat Heisenberg’s version of the Copenhagen meeting and to re-state the ‘Heisenberg version’ of German innocence. “I carefully fixed in my mind every word that was uttered. It had to make a very strong impression on me that at the very outset you stated that you felt certain that the war, if it lasted sufficiently long, would be decided by atomic weapons. At that time I had no knowledge at all of the preparations under way in England and America, and when I did not reply and perhaps looked doubtful, you told me that I had to understand that in recent years you had occupied yourself almost exclusively with this question and were certain that it could be done. On the other hand, there was no hint on your part that efforts were being made by German physicists to prevent such an application of atomic science...... my alarm was not lessened by hearing from the others at the Institute that Weizsacker had stated how fortunate it would be for the position of science in Germany after the victory that you could help significantly towards this end.” 44 Jim Thomson www.safetyinengineering.com Von Weizsacker bomb patent

• A draft patent by Carl-Friedrich von Weizsacker for a plutonium bomb, dated 1941, has recently been found in Russian archives. • This further undermines the Jungk/Heisenberg/von Weizsacker/Powers idea that the German team were never interested in developing weapons.

45 Jim Thomson www.safetyinengineering.com Why did the project fail? - 2

The Goudsmit/Rose version: I. They were incompetent. II. They didn’t know how to make a bomb. III. They couldn’t even calculate the of a bomb. IV. They thought they could build a reactor without control rods. V. They were a bunch of amateurs: it was a one-man band where they were all in awe of Heisenberg, who was a prima donna. 46 Jim Thomson www.safetyinengineering.com How competent were the German team? Did they really understand: • The difference between a reactor and a bomb? • Delayed ? • The need for control rods? • An accurate value for the critical mass for a bomb?

47 Jim Thomson www.safetyinengineering.com , ALSOS, 1947

“The plain fact of the matter is that the Germans were nowhere near getting the secret of the atom bomb. Indeed, at the rate they were going and the direction they were taking, it is anybody’s guess if they would have arrived at it at all in any practicable period of time.”

48 Jim Thomson www.safetyinengineering.com Why did the project fail? - 3

The Hans Bethe version (1990): “The explanation is that the Germans rejected the separation of uranium isotopes as too difficult. They saw the fissionability of plutonium as the key to the entire project. Once you had a you could make plutonium, and once you had plutonium, you could make a bomb. However, if they had achieved the reactor, they would have found that the road from there to a bomb was still full of obstacles.”

However, the plutonium route was stymied by lack of heavy water...... 49 Jim Thomson www.safetyinengineering.com The truth: The Farm Hall transcripts, not published until 1992

• Ten of the German physicists were interned in Cambridgeshire from May 1945. • They didn’t known anything at all of the Manhattan project. • They still thought they were world leaders in nuclear research, and that they could do a deal with the Allies. • The bombing was announced on the BBC news at 9pm on 6th August. • They didn’t realise the building and its grounds were bugged:-

50 Jim Thomson www.safetyinengineering.com Some key German scientists at Farm Hall (8 of the 10)

Werner Otto Hahn Paul Harteck Walter Gerlach Heisenberg 1879-1968 1902-1985 1889-1979 1901-1976

Carl-Friedrich Carl Wirtz Kurt Diebner Erich Bagge von Weizsäcker 1910-1994 1905-1964 1912-1996 1912-2007

51 Jim Thomson www.safetyinengineering.com Farm Hall, 6th August 1945, dinner conversation, 9pm till late: HAHN: “If the Americans have a uranium bomb then you’re all second raters. Poor old Heisenberg.”.... HEISENBERG: “All I can suggest is that some dilettante in America who knows very little about it has bluffed them...... I don’t believe a word of the whole thing.”.... von WEIZSACKER: “I don’t think it has anything to do with uranium.”..... GERLACH: “They’ve got (plutonium) and have been separating it for two years.”.... HEISENBERG: “I consider it perfectly possible that they have about ten tonnes of , but not that they can have ten tonnes of pure U-235.” (!!!??? Heisenberg doesn’t know the critical mass!!!!)..... HAHN: “But tell me why you used to tell me that one needed 50kg of 235...... now you say you need two tonnes?”..... HARTECK: “You could do it with 100,000 mass spectrographs”..... von WEISZACKER: “I believe the reason we didn’t do it was because all the physicists didn’t want to do it, on principle. If we had all wanted Germany to win the war we could have succeeded.” HAHN: “I don’t believe that.” von WEIZSACKER (after Hahn has left room): “If we had started this business soon enough we could have got somewhere.”...... WIRTZ: “It is characteristic that the Germans made the discovery and didn’t use it, whereas the Americans have used it.”...... GERLACH: “When we get back to Germany we will have a dreadful time. We will be looked on as the ones who have sabotaged everything. We won’t remain alive long there...... Isn’t it a pity that the others have done it? HAHN: “I am delighted.” 52 Jim Thomson www.safetyinengineering.com Farm Hall, 6th August 1945, later that evening:

• Heisenberg to Hahn: “One neutron always makes two others in pure 235. That is to say, in order to make 1024 neutrons I need 80 reactions, one after the other. Therefore I need 80 collisions and the mean free path is about 6 cm. In order to make 80 collisions, I must have a lump of a radius of about 54 centimetres and that would be about a tonne.”

• WRONG!!

53 Jim Thomson www.safetyinengineering.com Extract from the Frisch-Peierls memorandum, Birmingham, UK, March 1940

Extract from “The ” lecture notes, , April 1943

U-235 bomb

Pu-239 bomb

54 Jim Thomson www.safetyinengineering.com Conclusions from Farm Hall • There are parts of this story – particularly about motives and ethics – that will never be fully understood. • It seems that von Weizsäcker and Heisenberg didn’t want to go down in history as either scientific failures, or as closet Nazis. Instead, they tried to write their own history as saints. • This was a lie, and they were eventually found out.

55 Jim Thomson www.safetyinengineering.com So why didn’t Hitler get the Bomb? There is no single answer......

1. Until mid-1942, the German team was (arguably) in the lead. However, until 1942, the Germans thought the war would be over too soon for nuclear research to have any effect. After 1942, the bombing of Germany would have made any major new project very difficult. 2. If their priority had been the Bomb instead of the V weapons, things might have been different...... 3. The failure to use graphite as a moderator, and the destruction of the Vemork plant, were undoubtedly significant. 4. The German scientists seemed reluctant to push for a big project because they were uncertain of delivery. Arguably, no big project would have been sanctioned anyway until an operating reactor had first been demonstrated. 5. They didn’t pursue , or gas diffusion, for uranium enrichment. 6. Any claims that German scientists deliberately delayed developments, as part of passive resistance to the Nazi regime, now seem discredited.

56 Jim Thomson www.safetyinengineering.com Conclusion? Heisenberg, Harteck and Diebner might have been able to make an atomic bomb for Hitler in the time available. However: – The ‘time available’ was much longer than was realised in 1940. – They will have been concerned about the possibility, and the consequences, of failure if they talked up the Bomb. – There was no panic about ‘the other side getting there first’, because they thought they were first. Also, they were in a protected project which meant they were not likely to be conscripted.

“With the beginning of the war there arose of course for every German physicist the dreadful dilemma that each of his actions meant either a victory for Hitler or a defeat of Germany, and of course both alternatives presented themselves to us as appalling. Actually, I suppose that a similar dilemma must have existed for the physicists active on the allies' side as well, for once they were signed on during the war, they also were signed on for Stalin's victory and Russia's foray into Europe. Overall, the German physicists acted in this dilemma as conservators of sort of that which was worthy and in need of conserving, and to wait out the end of the catastrophe if one was lucky enough to still be around.”

Heisenberg letter to Robert Jungk, 1956 from http://werner-heisenberg.unh.edu/ 57 Jim Thomson www.safetyinengineering.com Recommended reading Downloads: 1. The Frisch-Peierls memorandum from March 1940: An unbelievably brilliant piece of work by two German Jewish exiles working alone in blacked-out Birmingham in the first winter of the war. This report started the and the ‘’ work in the UK. They were working for , who in 1941 went to the USA and persuaded the Americans to get serious about the Bomb. 2. “The Los Alamos Primer”, Robert Serber’s lecture notes from April 1943 for people who were new to the Manhattan project: This lays out the full scope of the project more than two years before it reached fruition. Books: 1. Jeremy Bernstein: Hitler’s Uranium Club: the Secret Recordings at Farm Hall (2nd Ed, 2001) gives the actual words spoken as they heard about the Manhattan project. 2. Mark Walker: German National Socialism and the Quest for Nuclear Power 1939-1949 (1989) is a detailed history. (It was actually Walker’s PhD thesis at Princeton). 3. Samuel Goudsmit, ALSOS (1947, republished 1996) is a good read, and it captures the raw emotions and paranoia of 1945. (Goudsmit’s parents had died at Auschwitz and some of his judgment seems clouded as a result.) 4. David Cassidy: Uncertainty, The Life and Science of Werner Heisenberg (1992) 5. David Irving: The Virus House (1968, out of print) gives a very good technical account. 6. Paul Lawrence Rose: Heisenberg and the Nazi Atomic Bomb Project (1998) is an outspoken critique of Heisenberg and Powers. 7. Arnold Kramish: The Griffin (1986) gives a fascinating account of the life of Paul Rosbaud, editor of the journal Naturwissenschaften, and a British spy. 8. Thomas Powers: Heisenberg’s War (1993) which continues the Heisenberg myth. 9. Rainer Karlsch: La Bombe de Hitler (2005, tr. into French 2007), a slightly hysterical and unlikely ‘history’ focussing on Diebner’s alleged activities in Gottow in 1944/45. 58 Jim Thomson www.safetyinengineering.com Recommended viewing

1. Copenhagen, stage play by Michael Frayn (1998) (available as BBC play on YouTube, with ) VERY GOOD – but too sympathetic to Heisenberg? 2. The Heroes of Telemark, directed by Antony Mann, starring Kirk Douglas and (1965) AWFUL - action thriller, low on context 3. BBC Horizon Hitler’s Bomb (1992) – contains fascinating interviews with von Weizsacker and Bagge, which make the programme too biased and sympathetic to the ‘Heisenberg version’ http://www.youtube.com/watch?v=eV-ElwRwdlM

Also: A play "" by Alan Brody, largely based on the Farm Hall transcripts, opened on March 7, 2013 in , Massachusetts. A staged reading of the play "Farm Hall" by David C. Cassidy, was presented on February 15, 2013 in the Science & the Arts program at The Graduate Center of the City University of New York. A second reading was performed on March 20, 2013 at the annual March meeting of The American Physical Society in Baltimore, Maryland.

59 Jim Thomson www.safetyinengineering.com Postscript: The lunatic fringes

60 Jim Thomson www.safetyinengineering.com Rainer Karlsch “Hitlers Bombe”

Rainer Karlsch, “Hitlers Bombe” (2005) (also “La Bombe de Hitler”, 2007):- “The G-IV reactor went critical in Gottow in late1944”. He says that radiation measurements have proved this, while others say it is just traces of fall-out from Cold War weapons tests or Chernobyl. My view: He is on the lunatic fringe...... BUT he did get Mark Walker to be his co-author in a paper summarising his ‘findings’ in Physics World, June 2005, “New light on Hitler’s Bomb”

Gottow c 2010. It was evacuated on 26th April 1945. The Red Army dismantled the site and some personnel continued work in the USSR. 61 Jim Thomson www.safetyinengineering.com See also: • Erster Atomreaktor der Welt oder die Uranmaschine http://www.youtube.com/ watch?v=0DKD99zMp4A Diebner seems to have done a good job of destroying paperwork at the end of the war. Hence activities at Gottow remain less clear than elsewhere. There are no known photos or diagrams of the G-IV pile.

Photos show the G-III pile in Gottow in 1943

http://www.deutsches-museum.de/archiv/archiv- online/geheimdokumente/forschungszentren/gottow/diebner-gottower-versuch-g- iii/dokument-4/

62 Jim Thomson www.safetyinengineering.com Rainer Karlsch - 2

• Rainer Karlsch also claims that two ‘weapon’ tests were carried out in Ruegen (in the Baltic) in October 1944 and Ohrdruf (Thuringia) in March 1945, under Kurt Diebner’s control. • Karlsch claims that the tests involved attempted fusion devices, using conventional explosives and . His evidence for this is flimsy to say the least. • He goes on to claim that one of the tests killed 500 prisoners of war, which sounds highly unlikely. • However, Irving (1968) also said that crude efforts at fusion were attempted. • Also, in 1957 Diebner took out a patent for a ‘fusion device’ using implosion with conventional explosives and electric arcing. • So-called ‘fourth generation’ or pure fusion bombs (using chemical explosives to trigger fusion) have apparently never been produced to date.....

63 Jim Thomson www.safetyinengineering.com Rainer Karlsch - 3

• Rainer Karlsch also found a German drawing of a bomb, dated c 1945/1946 of unknown source. • It is definitely post-war – so it proves nothing..... • Also, it shows a gun- style plutonium bomb – which wouldn’t work......

64 Jim Thomson www.safetyinengineering.com The Daily Mail......

Daily Mail, 13th July 2011 Nazi nuclear waste from Hitler's secret A-bomb programme found in mine “126000 barrels of waste found 2000 feet down in old salt mine near Hamburg.”

This sounds extremely unlikely! Mark Walker is quoted as saying 'Because we still don’t know about these projects, which remain cloaked in WW2 secrecy, it isn’t safe to say the Nazis fell short of enriching enough uranium for a bomb. Some documents remain top secret to this day. Claims that a was tested at Ruegen in October 1944 and again at Ohrdruf in March 1945 leave open a question, did they or didn’t they?'

65 Jim Thomson www.safetyinengineering.com “Soviets got U from Berlin”

• “The Soviets got 300 tonnes of natural uranium from the Auer factory in Berlin at the end of the war.” It is claimed this helped to kick-start their bomb programme.

• This seems plausible to me.

66 Jim Thomson www.safetyinengineering.com Atucha 2 PHWR, Argentina: A unique design with U-nat fuel , pressure vessel design, on-load refuelling.

SS Otto Hahn – nuclear powered cargo ship, operated 1968-1979.

Post-war legacy 67 Jim Thomson www.safetyinengineering.com Thank you!

68 Jim Thomson www.safetyinengineering.com Extra material

69 70 Pre-WW2 history of heavy water, and other trivia

Heavy water was first isolated in 1931. (E. W. Washburn and H. C. Urey, Proc. Nat. Acad. Sci. 18 (1932) 496) won the Nobel Prize in 1934. (Urey worked on uranium enrichment using gaseous diffusion during WW2 although Little Boy (Hiroshima) used U-235 produced using electromagnetic separation (‘Calutrons’)).

It is necessary to electrolyse 2700 litres of natural water to obtain one litre of water enriched in deuterium by 10%; this requires 320 MW-hours of electrical energy. By repeating the process of electrolysis, pure heavy water can be produced; this is a conceptually simple method but it is very expensive.

Small amounts (grams) for scientific use were available in the United States by 1933.

Yes, you can drink it.

Jomar Brun, the Head of Hydrogen Research at Norsk Hydro, and , a physicist from Trondheim, realized that the conditions for large-scale production (kg) of heavy water existed at Norsk Hydro’s plant in Rjukan, where large amounts of water were already being electrolyzed as part of the Haber-Bosch process for producing ammonia for nitrogen fertilizer.

They drew up a plan, with some involvement from Karl-Friedrich Bonhoffer, a German physical chemist at Leipzig (and brother of Dietrich, the anti-Nazi theologian who was hanged by the Nazis in April 1945), for the industrial production of heavy water. It was an impressive venture as a large amount of equipment had to be built – hundreds of combined electrolysis, combustion and condensation cells - and the market must have been uncertain. However, Norsk Hydro went ahead, and built a plant by the generator building at Vemork. First production of 99% pure D2O was in January 1935.

In 1937, Hans von Halban and Otto Frisch (again!!), working at Bohr’s Copenhagen laboratory, noticed that heavy water had very low neutron absorption compared to light water. 71 Jim Thomson www.safetyinengineering.com The practicality of fourth generation (pure fusion) bombs from The Question of Pure Fusion Explosions Under the CBTB, SL Jones and FN von Hippel, Science and Global Security, 1998, 7, pp 129-150 “The advent of the CTBT has probably also renewed interest at the weapons labs in attempting to ignite DT fusion directly using high-explosive implosion systems, if only because this will be one of the remaining experimental challenges that the designers of nuclear weapon implosion systems can use to hone their skills. Although US progress in this area is classified, in early1992 the Russian weapon laboratories reported neutron yields of 1013 -1014 neutrons, corresponding to the fusion of 10-10 to 10-9 grams of DT gas. The production of 1014 neutrons would be accompanied by the release of an amount of fusion energy equivalent to roughly 60 mg of TNT. The associated radiation dose at one meter would be about 0.2 Gy (20 rads) - significant but not great enough to cause death in the short term.

“Hans Bethe, who headed of the Los Alamos Theory Division during World War II, has expressed skepticism that such activities might lead to pure fusion weapons. However, he wrote a letter to President Clinton in April 1997 stating that "the time has come for our Nation to declare that it is not working, in any way, to develop further weapons of mass destruction of any kind. In particular, this means not financing work looking toward the possibility of new designs for nuclear weapons such as pure fusion weapons." If such a policy were announced, there would need to be more specific guidance with regard to permissible activities. The purpose of this paper is to begin laying a technical basis for such guidance.”

72 Jim Thomson www.safetyinengineering.com Gottow

• Experimental Station Gottow the Research Department of the Army Weapons Office (HWA). This division is divided into five sections, which are in turn subdivided into units, were, as the Unit I nuclear physics, physics and unit Ib explosive shaped charges, etc. experiment was mainly due to new weapons developments such as rocket motors, grenade launchers, rifles remain in the field of electronics, sound and acoustics, and various chemicals. The most famous experiments and developments test site were first developed under high involvement Wolfram Eschenbach N-material, an aggressive inorganic fluorine compound, which self-fire resistant materials are burned and built for a short time later a separate large underground plant Falkenhagen was. Secondly, the experiments Kurt thief agent in the development of a "uranium machine" to name in 3 trials (the trials GI to G III), he tried his team to a running nuclear reactor using a neutron source and cubes of natural uranium build. On 20/04/1945, the Army Research Office was Kummersdorf Gottow including the test site to evacuate. The test site Gottow by the Red Army, all existing facilities and equipment dismantled and confiscated. Some employees were asked for their scientific work in the to continue. In 1955/56, the area was transformed into an arms depot and expanded.

73 Enrichment – differences between German and UK/US approaches

• No attempt was made at large-scale electromagnetic separation (c.f. The Y-12 plant at Oak Ridge, which used ‘Calutrons’ – large cyclotrons – and produced the U235 for Little Boy). • No attempt was made at developing gas diffusion technology (c.f. The K-25 plant at Oak Ridge, and also Capenhurst in Cheshire for the UK nuclear programme after WW2.)

74 Jim Thomson www.safetyinengineering.com