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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
A typical cobalt-60 capsule, comprising: (A) An international standard source holder (usually lead), (B) a retaining ring, and (C) a teletherapy "source" composed of (D) two nested stainless steel canisters welded to two (E) stainless steel lids surrounding an (F) internal shield (usually uranium metal or a tungsten alloy) that protects a (G) cylinder of radioactive source material.
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.
The truck, now contaminated by the cobalt-60, subsequently suffered a mechanical failure upon Sotelo's return from the junkyard and remained immobile near his home in Ciudad Juárez for 40 days. [4] Meanwhile, at the junkyard, the use of electromagnets for handling the scrap caused the cobalt-60 granules to spread throughout the yard.
In 1974, Axt calibrated a cobalt-60 teletherapy unit with an incorrect decay curve. The calculated decay rate was more rapid than the real source, leading to a dose rate underestimated by 10–45% and an overestimated treatment time. [2] [3] No other calibrations and checks were performed between May 1974 and January 1976. Axt later attributed ...
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After retrieval from the core, processing can extract the cobalt-60 for manufacture into a useful radiation source. The vast majority of the world's cobalt-60 supply - over 80% - has traditionally come from Canada's National Research Universal (NRU) reactor at Chalk River. In general, the supply situation for medical and industrial isotopes is ...
In Nevil Shute's novel On the Beach (1957), cobalt bombs are mentioned as the cause of the lethal radioactivity that is approaching Australia. The cobalt bomb was a symbol of man's hubris. [13] In City of Fear (1959), an escaped convict from San Quentin State Prison steals a canister of cobalt-60, thinking it contains drugs. He flees to Los ...