Uranium isotope separation in the UK during World War II
This thesis investigates the practical, rather than theoretical, aspects of the uranium
isotope separation technology developed in the United Kingdom during the Second
World War. The overall scientific control of the bomb project was initially under G.P.
Thomson but later devolved to Chadwick. Simon, at the University of Oxford,
oversaw the practical aspects of isotope separation while Peierls, at Birmingham, was
largely responsible for the theory, although many other leading scientists were
involved in both the choice of a separation method and the associated measurement
techniques required for its application.
Frisch, the joint proposer of fission, was working on uranium isotope separation prior
to the end of 1939. Frisch and Peierls produced a memorandum, in March 1940,
which set the u.K. project in motion and eventually triggered the Americans into
action. The Frisch-Peierls Memorandum led to the formation of the M.A.U.D.
Committee which produced its report in July of 1941 that confirmed the scientific
feasibility of such a weapon. A new and larger organisation, Tube Alloys, was then
formed to complete the project.
Virtually all methods of isotope separation were investigated before the choice of gas
diffusion through a porous membrane was made. Most of the other methods became
viable in the post war period or were applied to elements other than uranium.
Two main problems had to be solved in the gas diffusion system: the design of a gas
compressor system capable of operating at low absolute pressure, and the manufacture
of a suitable diffusion membrane. A whole variety of membranes were investigated
and a number taken to pilot production stage by small commercial firms.
Experimental machines were designed and a pilot production plant constructed. The
separation properties of both membranes and the diffusion machine were
demonstrated. The transfer of core members of the team to America prevented
completion of this work during the wartime period.
The Americans, with their strong economy, wider range of scientific facilities, and
enormous manufacturing capability, gradually assumed a leading role in the atomic
work. The realisation that both the construction of both the separation plant and the
manufacture of a bomb was beyond the financial and production capability of the
U.K. led to the transfer of the leading members of the British team to America to
pursue the project.