Nuclear Secrets Revealed on 75th Anniversary of Neutron Discovery

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Instructions on how to make plutonium and build a nuclear reactor have been revealed in sealed, World War II research papers which were opened at the Royal Society on Thursday 31 May 2007 to coincide with the 75th anniversary of the neutron discovery.

Between 1940 and 1941 James Chadwick sent five sealed envelopes to the Royal Society for safe keeping as he felt their contents detailing experiments on nuclear fission were too sensitive to publish. The sealed envelopes contained the work of two French scientists, Hans Von Halban and Lew Kowarski who worked at the Cavendish laboratory in Cambridge.

Chadwick's discovery of the neutron confirmed in his 1932 paper The Existence of a Neutron' published in Proceedings of the Royal Society A kickstarted the field of nuclear physics.

Keith Moore, Head of Library and Archives at the Royal Society, said "The papers have only recently been discovered, as part of our on-going programme to catalogue the Society's archives. The documents have been sealed for so long it only seemed right to wait for an occasion to open them. The anniversary of Chadwick's discovery which made the research outlined in these papers possible seemed fitting."

Dr Brian Cox, particle physicist and Royal Society research fellow working at CERN, said: "These papers describe what was cutting edge science at the time. The sheer amount of knowledge that these papers contain amazes me only eight years after Chadwick discovered that a neutron even existed, these scientists are already looking at how to use neutrons to bring about nuclear fission and energy.

"I can see why these papers were locked away during the war they contain details that could be used to build a nuclear reactor."

The research papers demonstrate the rapid progress being made in the field at the time, and the huge potential of nuclear fission for power generation. However the knowledge that the huge energy releases from nuclear fission could also be used irresponsibly, prompted Chadwick to emphasise in his letters which accompanied the sealed documents that it was "inadvisable to publish at the present time".

Keith Moore added: "Research to understand nuclear fission was an international endeavour. These papers would, under normal circumstances, have been published in a scientific journal to share new knowledge. However, the outbreak of war marked the end of nuclear science being a collective investigation and new developments rapidly became sensitive information."

One paper, "Technological aspects of nuclear chain reactions used as a source of power" dated October 1941, describes the various components required to make a nuclear reactor or boiler' as it is referred to in the typewritten text. The paper describes the process of making plutonium from uranium as a means to generate "new nuclei" which are required to initiate and maintain nuclear fission. The paper also documents various experiments using iron, aluminium, sulphur, graphite and heavy water as a means to stabilise nuclear chain reactions to generate constant energy rather than mass explosions.

In their papers, Halbarn and Kowarski also hypothesize that "the future nuclear industry may rely on uranium" a theory that has since been proved correct with uranium being used in the majority of today's commercial nuclear power stations.

Brain Cox added: "These papers are a truly significant part of nuclear history. They provide a fascinating insight into the inquisitive nature of scientists working in a field moving so rapidly it was almost outpacing them. It is fascinating to read their views on what might come of their research and how accurate some of their predictions have been."

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