The Atomkeller-Museum at Haigerloch
N 48° 22.036 E 008° 48.245
32U E 485489 N 5357140
In the last days of WWII, German scientific experiments into nuclear fission were carried out in this underground room dug into the side of a cliff. As the allies invaded Germany, the American forces were focused on capturing this sensitive location.
Waymark Code: WM1CTW
Location: Baden-Württemberg, Germany
Date Posted: 04/07/2007
Views: 393
Parking is available very near to the museum. An interpretive book in English is available for €3.00 and is strongly recommended as the museum exhibits are otherwise only in German.
Nuclear fission was discovered in Germany in 1938-1939 through the work of Otto Hahn, Fritz Strassmen, Lise Meitner, and Otto Robert Frisch (following up on work done by Enrico Fermi). By the beginning of World War II the scientific community was well aware of the early German lead in this area of nuclear physics.
The threat of a Nazi atomic bomb was one of the primary driving forces behind the creation of the British Tube Alloys project which would eventually lead to the Allied nuclear weapons effort: the Manhattan Project. Several European exiles from Germany, Italy, Hungary and other nations eventually would make significant contributions to the Allied nuclear effort. The German government never did finance a full crash program to develop weapons, as they estimated it could not be completed in time for use in the war, thus the German program was much more limited in capacity and ability when compared to the eventual size and priority of the Manhattan Project.
In 1945, a U.S. investigation called Project Alsos determined that German scientists under Heisenberg were close, but still short, of the point that Allied scientists had reached in 1942, the creation of a sustained nuclear chain reaction, a crucial step for creating a nuclear reactor (which in turn could be used for either peaceful purposes, or for creating plutonium, needed for nuclear weapons).
In 1939, it was soon recognized in Germany that it might be possible to bring about a neutron chain reaction of such splitting with a subsequent release of a vast amount of energy. As early as the summer of 1939, Siegfried Flügge had published a newspaper article openly discussing these possibilities.
When World War II began, the experiments were declared secret. They were turned over to the Army Weapons Office in Berlin and were looked after by Kurt Diebner, who got the Kaiser Wilhelm Institute for Physics involved in these experiments. Early on, Werner Heisenberg directed their work.
The total German research work during the War was concentrated on the construction of a nuclear reactor. However, v. Weizsäcker recognized early that a bomb could be realized with the Plutonium, that would be produced in the reactor and that could be extracted easily.
At a meeting at the Heereswaffenamt in February 1942, Heisenberg replied to the question, if there could be built a war-decisive weapon within nine months, with a clearcut "No". Thereupon, the Nazis lost their interest in the project. The responsibility for the entire enterprise was withdrawn from the Heereswaffenamt and transferred to the Reichsforschungsrat (National Research Council). The control of this project was taken over by Walter Gerlach in 1944.
By 1943, the air raids on Berlin were becoming so intense that work became impossible there. An area was sought which was still relatively safe from air attacks. South-West-Germany had largely been spared from such attacks so far. It was also foreseen that in the event of occupation, hardly any Soviet troops would penetrate into this area. The scientists by no means wanted to fall prey to the Soviet Union as an occupational power.
Walter Gerlach, who studied physics in Tübingen and had been professor there, probably recalled the area around Hechingen and Haigerloch. He proposed building a laboratory within a bunker in the narrow limestone valley of the Eyach-River, since it was considered safer from air raids. During their visit to Haigerloch, it was pure coincidence that caused the scientists to find the rockhewn beer cellar of the "Schwanen Inn" and they could rent it for their work.
In an adventuresome trip by truck from Berlin to Haigerloch, the uranium and the heavy water was relocated from Berlin to Haigerloch, where the famous "B8"-experiment was able to be carried out at the end of March and the beginning of April.
The reactor was located in a concrete cylinder. Between the outer concrete shell and the inner aluminium shell normal water was filled in for cooling purposes. The aluminium container had a diameter of 210 cm and a height of 210 cm, and contained another vessel made of magnesium. The space between the two vessels was filled with a 40 cm layer of graphitic carbon bricks. These bricks provided an external shield which prevented the escape of neutrons generated during the fission. The 664 uranium cubes (edge lenght of 5 cm) attached to the lid were then lowered into the inner magnesium vessel. It was a spatial grid, and the distance between the closest was 14 cm. Subsequently, the lid was bolted onto the reactor.
A neutron source was inserted into the center of the installation through the so-called chimney. There were openings in the top for the insertion of the so-called neutron probes to determine an exact measurement of the distribution of neutrons inside the apparatus, in the surrounding graphite bricks, and in the light water in the tank. Lastly, the heavy water was poured in slowly and carefully and the proliferation of the neutrons measured during the filling-up operation. If the reactor had become critical, the experiment would have been terminated.
The ratio of measurement with to the measurement without uranium and the heavy water is called the multiplication factor. It came to about seven. By this, the reactor didn't become critical. Further calculations showed that a functioning nuclear reactor would have had to be about 1.5 times the size of this reactor. However, expanding the reactor was no longer possible in April 1945 due to the lack of both heavy water and additional quantities of uranium blocks.
Shortly after conducting the last experiment, Haigerloch, located within the French zone of occupation, was occupied by a special American Task Force. This was the so-called "ALSOS-Mission".
Colonel Pash, the commander of this unit, took the scientists prisoner in their offices and private homes at Hechingen. Shortly before this, Heisenberg had fled by bike to his family in Bavaria, but was taken prisoner some time later.The Americans found the Uranium metal and the Heavy Water, which was hidden shortly before by the German scientists and was dug up.
They also dismantled the facilites in the cellar and took them to the US.
The American Forces had been ordered to blow up the cellar. The then parish priest took Colonel Pash into the baroque Schloßkirche (caslte church) directly above the cellar, and explained that the destruction of the cellar would also mean the destruction of the church. Knowing this, the Americans confined themselves to limited demolition operations in the cellar.
The scientists were interned in the "Farmhall" country house near Cambridge by the Allied Powers and kept prisoners there until January 1946 ("as guests of His Majesty").
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Admission Fee: €1.50
Opening Days/Times:
1 May to 30 September: daily from 10.00-12.00 h and from 14.00-17.00 h
1 October to 30 November and from 1 March to 30 April: Saturdays, Sundays and Public Holidays from 10.00-12.00 h and from 14.00-17.00 h
Closed from 1 December to 28 February
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Visit Instructions:
Posting a picture(s) of the location would be nice although not required.