Cobalt bomb
A cobalt bomb is a theoretical type of "salted bomb": a nuclear weapon designed to produce enhanced amounts of radioactive fallout, intended to contaminate a large area with radioactive material. The concept of a cobalt bomb was originally described in a radio program by physicist Leó Szilárd on February 26, 1950.[1] He suggested that an arsenal of cobalt bombs would be capable of destroying all human life on Earth (though his conclusions are disputed).[2][3]
As far as is publicly known, no cobalt bombs have ever been built. The Operation Antler/Round 1 test by the British at the Tadje site in the Maralinga range in Australia on September 14, 1957 tested a bomb using cobalt pellets as a radiochemical tracer for estimating yield. This was considered a failure and the experiment was not repeated.[4]
Mechanism
A cobalt bomb could be made by placing a quantity of ordinary cobalt metal (59Co) inside a nuclear bomb. When the bomb explodes, the neutrons produced by the explosion would transmute the cobalt to the radioactive isotope cobalt-60 (60Co), which would be vaporized by the explosion. The cobalt would then condense and fall back toeEarth with the dust and debris from the explosion, contaminating the ground.
The deposited Cobalt-60 would have a half-life of 5.27 years, decaying into 60Ni. The nickel nucleus is activated, and emits two gamma rays with energies of 1.17 and 1.33 MeV, hence the overall nuclear equation of the reaction is:
59
27Co
+ n → 60
27Co
→ 60
28Ni
+ e− + gamma rays.
Nickel-60 is a stable isotope and undergoes no further decays after emitting the gamma rays.
The 5.27 year half life of the 60Co is long enough to allow it to settle out before significant decay has occurred. The half-life is long enough for it to be impractical to wait in shelters for it to decay, yet short enough that intense radiation is produced.[4] Many isotopes are more radioactive (gold-198, tantalum-182, zinc-65, sodium-24, and many more), but they would decay faster, possibly allowing some population to survive in shelters.
In a fission bomb, it has been suggested, the weapon's tamper could be made of cobalt. In a fusion bomb the radiation case around the weapon, normally made of uranium 238, could be made of cobalt. These changes would reduce the explosive power (yield) of the weapon somewhat.
References
- ^ Brian Clegg. Armageddon Science: The Science of Mass Destruction. St. Martins Griffin. p. 77. ISBN 978-1-250-01649-2.
- ^ Samuel Glasstone; Philip J. Dolan, eds. (1977). The Effects of Nuclear Weapons (PDF) (Report) (3rd ed.). Washington, D.C.: United States Department of Defense and Department of Energy.
- ^ Martin (1982). "The global health effects of nuclear war". Current Affairs Bulletin. 59 (7): 14–26.
{{cite journal}}:|first=missing|last=(help); Unknown parameter|month=ignored (help) - ^ a b "1.6 Cobalt Bombs and other Salted Bombs". Nuclearweaponarchive.org. Retrieved 10 February 2011.