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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.
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
According to the 1985 CNSNS report, about four thousand people were exposed to cobalt-60 radiation as a result of the incident. [3] It is estimated that almost 80 percent of people received a dose less than 500 mrem (equivalent to 5 m Sv ); 18 percent, between 0.5 and 25 rems (5–25 mSv); and only two percent (about 80 people) received doses ...
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.
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 ...
Cobalt-60 Teletherapy Capsule. The radiotherapy accident in Costa Rica occurred within the Alcyon II radiotherapy unit at San Juan de Dios Hospital in San José, Costa Rica. It was related to a cobalt-60 source that was being used for radiotherapy in 1996. An accidental overexposure of radiotherapy patients treated during August and September ...
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 ...
Cobalt-60 Production: The least complex of current uses of the Advanced Test Reactor is the production of the 60 Co radioisotope for medical uses. Disks of cobalt-59 1 mm -diameter by 1 mm thick are inserted into the reactor (Static Capsule Experiment), which bombards the sample with neutrons, producing cobalt-60.