The first atomic bomb

The first atomic bomb was successfully tested by the U.S. near Alamogordo, N.Mex., on July 16, 1945 (The MANHATTAN PROJECT). In the final stages of WORLD WAR II the U.S. dropped atomic bombs on Hiroshima on Aug. 6, 1945, and on Nagasaki three days later. Atomic bombs were then developed by the USSR in 1949, Great Britain in 1952, France in 1960, China in 1964, and India in 1974, and a numerous of other nations. The USSR's nuclear arsenal has been divided since 1991 among Russia, Ukraine, Kazakhstan, Belarus and more. Practical fissionable nuclei for atomic bombs are the isotopes URANIUM-235 and PLUTONIUM-239, which are capable of undergoing chain reaction. If the mass of the fissionable material exceeds the critical mass, the chain reaction multiplies rapidly into an uncontrollable release of energy. An atomic bomb is detonated
by bringing together very rapidly two sub critical masses of fissionable material. The ensuing explosion produces great amounts of heat, a shock wave, and intense neutron and gamma radiation. The region of the explosion becomes radioactively contaminated, and wind-borne radioactive products are deposited elsewhere as fallout.


After one detonation, unusually heavy fallout was noted as far from Nevada as the Troy-Albany area in New York.  Following a heavy rain in that area on the second day after the detonation, the concentration of radioactivity was from 100 to 200 curies per square mile.  It is estimated that this level of radioactivity would result in about 0.1 roentgen exposure for the first 13 weeks following the fallout.

Low-level radiation from Hiroshima to Three Mile Island.
    RA569.S69 1981    616.9'897  80-22390
    ISBN O-07-061242-0

Nuclear Future, Present, Past.
 

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