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Cobalt-60, 60 Co. Cobalt-60 (60 Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2714 years. [3][4]: 39 It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activation of bulk samples of the monoisotopic and mononuclidic cobalt isotope 59. . [5]
The first operational nuclear reactor outside the United States - the NRX - was located at Chalk River, and it provided a source of activated cobalt-60 for Johns's experiments. Two groups - Johns's at the University of Saskatchewan, and another one in London, Ontario - designed and constructed external beam radiotherapy instruments using ...
Neutron activation is the only common way that a stable material can be induced into becoming intrinsically radioactive. All naturally occurring materials, including air, water, and soil, can be induced (activated) by neutron capture into some amount of radioactivity in varying degrees, as a result of the production of neutron-rich radioisotopes.
The deposited cobalt-60 would have a half-life of 5.27 years, decaying into 60 Ni and emitting two gamma rays with energies of 1.17 and 1.33 MeV, hence the overall nuclear equation of the reaction is: 59 27 Co + n → 60 27 Co → 60 28 Ni + e − + gamma rays. Nickel-60 is a stable isotope and undergoes no further decays after the ...
Fission products are as deadly as neutron-activated cobalt. Initially, gamma radiation from the fission products of an equivalent size fission-fusion-fission bomb are much more intense than Cobalt-60 (60 Co): 15,000 times more intense at 1 hour; 35 times more intense at 1 week; 5 times more intense at 1 month; and about equal at 6 months.
Cobalt therapy is the medical use of gamma rays from the radioisotope cobalt-60 to treat conditions such as cancer. Beginning in the 1950s, cobalt-60 was widely used in external beam radiotherapy (teletherapy) machines, which produced a beam of gamma rays which was directed into the patient's body to kill tumor tissue.
There the cobalt would be activated by the neutron flux in the reactor and become cobalt-60, a radioisotope with a five-year half life that releases very energetic gamma rays. This phenomenon is more problematic in boiling water reactor (BWR) plants, since the steam is in direct contact with both the reactor and the steam turbine.
A radiation accident occurred in Samut Prakan Province, Thailand in January–February 2000. The accident happened when an insecurely stored unlicensed cobalt-60 radiation source was recovered by scrap metal collectors who, together with a scrapyard worker, subsequently dismantled the container, unknowingly exposing themselves and others nearby to ionizing radiation.