- Cobalt bomb
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For cancer radiation treatments delivered from a device with a cobalt-60 isotope source, see Cobalt therapy.
A cobalt bomb is a theoretical type of "salted bomb": a nuclear weapon intended to contaminate an area by radioactive material, with a relatively small blast.
The weapon's tamper would be composed of ordinary cobalt metal, which the nuclear explosion would then transmute to the radioactive isotope cobalt-60 (60Co), which would produce deadly nuclear fallout.
As far as is publicly known, no cobalt bombs were ever built. The Operation Antler/Round 1 test by the British at the Tadje site in the Maralinga range in Australia on 14 September 1957 tested a bomb using cobalt as a radiochemical tracer, but was considered a failure.[1]
Mechanism
The cobalt tamper would be transmuted into the isotope 60Co upon initiation and bombardment by neutron radiation. 60Co decays into an excited 60Ni by beta decay. The excited 60Ni then transitions to a ground state 60Ni, releasing gamma radiation.
The concept of a cobalt bomb was originally described by physicist Leó Szilárd, who suggested that an arsenal of cobalt bombs would be capable of destroying all human life on Earth (though his conclusions are disputed). Cobalt was chosen because of the fallout, that would have a half-life of 5.27 years and would be intensely radioactive at the same time. While there exist isotopes with a longer half-life than 60Co, they are also insufficiently radioactive.[1] 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.
To provide a point of reference: to equally distribute 1 gram of cobalt per square kilometer of Earths surface one would need 510 tonnes,[2] and fallout does not reach all areas in equal amounts.[2][3] While the sheer size and cost of such a weapon makes it unlikely to be built, it is technically possible because there is no maximum size limit for a thermonuclear bomb.
However, the effects of nuclear weapons, including blast, physical damage and fallout, do not scale up linearly with weapon size or yield; the magnitude of these effects increases more gradually than the energy released by the nuclear detonation. Stratospheric scientist and Australian peace activist Brian Martin has published analyses demonstrating this crucial weakness in the idea that the planetary nuclear arsenal is several times as large as that required to destroy all life on Earth; this analysis would have implications for the real versus the assumed lethality of the cobalt bomb to all life on Earth.[3]
References
- ^ a b "1.6 Cobalt Bombs and other Salted Bombs". Nuclearweaponarchive.org. http://nuclearweaponarchive.org/Nwfaq/Nfaq1.html#nfaq1.6. Retrieved 10 February 2011.
- ^ a b The Effects of Nuclear Weapons, Samuel Glasstone and Philip J. Dolan (editors), United States Department of Defense and Department of Energy, Washington, D.C., http://www.alternatewars.com/WW3/WW3_Documents/Weapon_Effects/Effects_1977_09.pdf
- ^ a b Brian Martin, "The global health effects of nuclear war," Current Affairs Bulletin, Vol. 59, No. 7, December 1982, pp. 14-26. http://web.archive.org/web/20090502091427/http://www.uow.edu.au/arts/sts/bmartin/pubs/82cab/
Categories:- Nuclear weapons
- Cobalt
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