The concept was also used in some other works of fiction at well. Strangelove, the Soviet Union had established a secret nuclear deterrent comprising 50 buried cobalt bombs. In the 1957 novel On the Beach by Nevil Shute (and the films based on it), the death of all humanity is brought about by the detonation of cobalt bombs in the Northern Hemisphere. Dick ends with the newspaper headline "RUSSIA REVEALS COBALT BOMB TOTAL WORLD DESTRUCTION AHEAD". The 1954 science fiction short story " Exhibit Piece" by Philip K. The concept of cobalt bombs has been used in a number of works of apocalyptic fiction. As a result, the rate of cancer incidence in the survivor population would likely increase.Īfter 27 half-lives (about 142 years), the dose rate from Cobalt-60 would have decayed to less than 1 mSv/year and could be considered negligible. However, this yearly dose rate is on the order of 30 times greater than the peacetime exposure rate of 2.5 mSv/year. At this stage, humans could remain unsheltered full-time since their yearly radiation dose would be about 80 mSv. At this point, a healthy person could spend 1 to 4 days exposed to the fallout with no immediate effects.Īfter 20 half-lives (about 105 years), the dose rate would have decayed to around 10 μSv/hour. At this dose rate, a person exposed to the radiation would receive a lethal dose in 1 hour.Īfter 10 half-lives (about 53 years), the dose rate would have decayed to around 10 mSv/hour. People in well-built shelters would be safe due to radiation shielding.Īfter one half-life of 5.27 years, only half of the Cobalt-60 will have decayed, and the dose rate in the affected area would be 5 Sv/hour. At this dose rate, any unsheltered person exposed to the fallout would receive a lethal dose in about 30 minutes (assuming a median lethal dose of 5 Sv). These changes would reduce the explosive power ( yield) of the weapon somewhat.Īssume a cobalt bomb deposits intense fallout causing a dose rate of 10 sieverts (Sv) per hour. In a fusion bomb the radiation case around the weapon, normally made of 238U, could be made of cobalt. In a fission bomb, it has been suggested, the weapon's tamper could be made of cobalt. 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. The 5.27 year half life of the 60Co is long enough to allow it to settle out before significant decay has occurred, and for it to be impractical to wait in shelters for it to decay, yet short enough that intense radiation is produced. Nickel-60 is a stable isotope and undergoes no further decays after emitting the gamma rays. 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: The deposited Cobalt-60 would have a half-life of 5.27 years, decaying into 60Ni. The cobalt would then condense and fall back to Earth with the dust and debris from the explosion, contaminating the ground. 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. A cobalt bomb could be made by placing a quantity of ordinary cobalt metal ( 59Co) inside a nuclear bomb.
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