Uranium hydride bomb

The uranium hydride bomb was a variant of the atomic bomb, first suggested by Robert Oppenheimer in 1939 and advocated and tested by Edward Teller. It would use deuterium (an isotope of hydrogen) in a U235-deuterium compound. However, the process failed to have the necessary explosive power in practice.

Theory

The hydrogen in uranium hydride (UH3) moderates the neutrons, such that the fission cross section of the uranium is greater than that of pure U235. This would mean a lower critical mass. However, the slower neutrons mean the reaction takes too long for an efficient weapon. The nuclear fission chain reaction would then be slow neutron fission (thermal energy). Bomb efficiency is very adversely affected by the slowing down of the neutrons since it gives the bomb core more time to blow apart. The predicted energy yield would be 1000 tons TNT equivalent. [ [http://nuclearweaponarchive.org/Usa/Tests/Upshotk.html Operation Upshot-Knothole] (Nuclear Weapon Archive)]

1953 tests

After World War II, Los Alamos physicists were skeptical of uranium hydride in weapons. Edward Teller remained interested, however, and he and Ernest Lawrence experimented with the devices in the early 1950s at UCRL (later Lawrence Livermore National Laboratory).

RUTH, which used ordinary hydrogen-1, was the first device entirely designed at Livermore; it was fired on March 31, 1953 at 05:00 local time (13:00 GMT) at Mercury, Nevada. The explosive device, Hydride I, weighed 7400lb and was 56 inches in diameter and 66 inches long. The predicted yield was 1.5 to 3.0 kilotons, but the actual yield was only 200 tons. Wally Decker, a young Laboratory engineer, characterised the sound the shot made as "pop." The 200 feet of the 300-foot-tall testing tower remained intact, although the upper third was destroyed.

A second device, RAY, used deuterium. It was fired on a 100-foot tower on April 11, 1953. Although RAY managed to level the tower, the yield was similarly disappointing: again 200 tons, as opposed to the predicted 0.5-1 kT. [ [http://www.globalsecurity.org/wmd/systems/w48.htm Weapons of Mass Destruction: W48] (GlobalSecurity.org)]

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