The Atomic Technology of War:

The Atomic Technology of War:

The spread of atomic weapons.

Scientists in several countries performed experiments in connection with nuclear reactors and fission weapons during World War II, but no country other than the United States carried its projects as far as separating uranium-235 or manufacturing plutonium-239.

The Axis powers

By the time the war began on Sept. 1, 1939, Germany had a special office for the military application of nuclear fission; chain-reaction experiments with uranium and carbon were being planned, and ways of separating the uranium isotopes were under study. Some measurements on carbon, later shown to be in error, led the physicist Werner Heisenberg to recommend that heavy water be used, instead, for the moderator. This dependence on scarce heavy water was a major reason the German experiments never reached a successful conclusion. The isotope separation studies were oriented toward low enrichments (about 1 percent uranium-235) for the chain reaction experiments; they never got past the laboratory apparatus stage, and several times these prototypes were destroyed in bombing attacks. As for the fission weapon itself, it was a rather distant goal, and practically nothing but "back-of-the-envelope" studies were done on it.

Like their counterparts elsewhere, Japanese scientists initiated research on an atomic bomb. In December 1940, Japan's leading scientist, Nishina Yoshio, undertook a small-scale research effort supported by the armed forces. It did not progress beyond the laboratory owing to lack of government support, resources, and uranium.

Great Britain.

The British weapon project started informally, as in the United States,among university physicists. In April 1940 a short paper by Otto Frisch and Rudolf Peierls, expanding on the idea of critical mass, estimated that a superweapon could be built using several pounds of pure uranium-235 and that this amount of material might be obtainable from a chain of diffusion tubes. This three-page memorandum was the first report to foretell with scientific conviction the practical possibility of making a bomb and the horrors it would bring. A group of scientists known as the MAUD committee was set up in the Ministry of Aircraft Production in April 1940 to decide if a uranium bomb could be made. The committee approved a report on July 15, 1941, concluding that the scheme for ...

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...l U.S. or Soviet tests, the first Chinese detonation--on Oct. 16, 1964--used uranium-235 in an implosion-type configuration. Plutonium was not used until the eighth explosion, on Dec. 27, 1968.

Other countries

On May 18, 1974, India detonated a nuclear device in the Rajasthan desert near Pokaran with a reported yield of 15 kilotons. India characterized the test as being for peaceful purposes and apparently did not stockpile weapons. Pakistan declared its nuclear program to be solely for peaceful purposes, but it acquired the necessary infrastructure of facilities to produce weapons and was generally believed to possess them.

Several other countries were believed to have built nuclear weapons or to have acquired the capability of assembling them on short notice. Israel was believed to have built anrsenal of more than 200 weapons, including thermonuclear bombs. In August 1988 the South African foreign ministersaid that South Africa had "the capability to [produce a nuclear bomb] should we want to." Argentina, Brazil, South Korea, and Taiwan also had the scientific and industrial base to develop and produce nuclear weapons, but they did not seem to have active programs.