Espelkamp
World War II researchers Dirk Finkemeier & former British Army officer Keith Sanders claim that Sanders's father, an NCO with RAOC engineers, discovered an underground nuclear facility at Espelkamp, in North Rhine–Westphalia on or about 4th April 1945.
Inside was claimed to be uranium centrifuge cascades and what was described to me only as a working Krupp nuclear reactor.
Because the Germans were also known to have built underground Uranium centrifuge facilities at other locations such as Kandern and also because the Anschultz Co. in Hamburg was contracted to mass produce centrifuges in 1944 their claim about Espelkamp seems quite plausible.
More so actually because after WW2 numerous Nazi nuclear scientists earlier held at Farm Hall were moved to Alswede, a little Hamlet right next to Espelkamp where they continued to work for the British on Britain’s Nuclear weapons program until 1948.
Given that Alswede had no nuclear facility, this appears to back up the claim that the British kept Espelkamp in operation well after WW2 and kept it a fiercely guarded secret from the Soviets.
After the British abandoned the underground complex they sealed the tunnels and bulldozed over the entrances. The area was turned into a shelter for 2,500 former German POWs returning home from Soviet POW camps. Eventually a school was built over the entrance and then some years ago the school had to be closed when unusually high numbers of children became ill with radiation sickness.
There has been a deliberate campaign of disinformation since WW2 about the Nazi nuclear program focused on the failure of Dr Werner Heisenberg to attain a nuclear chain reaction. Heisenberg headed Uranverin 2, which was a civilian research group of University scholars.
The earlier group Uranverin 1 was disbanded and reformed into a top secret military group which recruited chosen members of Uranverin 2 to join them. The military group worked in parallel and also performed experiments with nuclear reactors which by 1944 were more successful than Heisenberg’s team.
Diebner / Harteck Group
Specifically the Diebner team succeeded in producing neutron fluxes with Gottow II, Gottow III and Gottow IV.
Diebner’s team built their 2nd pile in April 1943 employing 232kg of uranium metal cubes latticed with 210kg of frozen deuterium. Despite the modest size they said it yielded the best neutron production coefficient of any pile.
Gottow III in July 1943 used 106 uranium cubes totaling 254kg, lacquered with new polystyrol emulsion, suspended in chains of 8 and 9, arranged so that each cube was 14.5cm from its 12 nearest neighbours, and moderated by 610kg of deuterium
Prof. H. Pose and Prof. E. Rexer – conducted small uranium and paraffin pile experiments, systematically varying the geometrical arrangements, proving in October 1943 that cubes were superior to rods, and rods were superior to plates. Heisenberg experimented with plates of Uranium. It is not recorded that these first three Gottow reactors obtained a chain reaction, however it is known there was a fourth reactor experiment about which there is little information.
The largest pile Gottow IV used 240 uranium cubes totaling 564kg, with 592kg / 165 Litres Heavy Water (Deuterium oxide), the larger resulted in a 6% increase in neutrons. It may be that the so called Krupp reactor at Espelkamp was Gottow IV or an improvement on that.
Different Research teams
The Military Group formed around Diebner & Harteck and used the euphamistic term “new energy sources as R-Drive” to suggest in official papers that they were a special team investigating rocket fuels. This team conducted research at underground complexes in Thuringia (Dreidecks region).
Manfred von Ardenne also had a separate private unit working in Dresden on developing Particle accelerators which today we would call Tokamaks to convert depleted Uranium from centrifuges into Plutonium 239. The largest of these was captured by ALSOS at Bissingen in April 1945, then dismantled in secrecy and shipped back to the United States.