Increased Occupational Radiation Doses

Abstract

The increased occupational doses resulting from the Chernobyl nuclear reactor accident that occurred in Ukraine in April 1986, the reactor accident of Fukushima that took place in Japan in March 2011, and the early operations of the Mayak Production Association in Russia in the 1940s and 1950s are presented and discussed. For comparison purposes, the occupational doses due to the other two major reactor accidents (Windscale in the United Kingdom in 1957 and Three Mile Island in the United States in 1979) and to the main plutonium-producing facility in the United States (Hanford Works) are also covered but in less detail. Both for the Chernobyl nuclear reactor accident and the routine operations at Mayak, the considerable efforts made to reconstruct individual doses from external irradiation to a large number of workers revealed that the recorded doses had been overestimated by a factor of about two.Introduction of Increased Occupational Exposures: Nuclear Industry Workers. (Video 1:32, http://links.lww.com/HP/A21).

Typical doses and dose rates in studies pertinent to radiation risk inference at low doses and low dose rates

“…The mean cumulative internal liver dose, largely from alpha-particle exposure, is 0.31 Gy, with a maximum of 36 Gy [ 35 ]. This compares with average annual effective doses of up to 1000 mGy recorded in the late 1940s, as reported by [ 38 ]. During 1948–1953, when doses to Mayak workers were the highest, the unshielded dosimeters had significant variability in photon energy dependence and angular response, and bias by high-energy beta exposures provided overestimates of doses for workers in some settings.…”

“…During 1948–1953, when doses to Mayak workers were the highest, the unshielded dosimeters had significant variability in photon energy dependence and angular response, and bias by high-energy beta exposures provided overestimates of doses for workers in some settings. Efforts were made to correct for those estimation biases, but such corrections likely had substantial uncertainties [ 33 , 38 ]. In addition, before 1957 unmeasured intermediate and fast neutrons were thought to have contributed 10–15% of the total dose [ 36 ].…”

“…Mean accumulated doses correspond to 161 mGy, 81 mGy and 35 mGy, respectively. However, doses to certain small groups of workers in certain specific periods were much higher, in excess of 500 mGy [ 38 ]. Based on these doses, it was estimated that daily average doses of those individuals correspond to 7.6 mGy/day (320 μGy/h), 4.7 mGy/day (200 μGy/h) and 2.6 mGy/day (110 μGy/h), respectively, if one assumes continuous exposure over the whole day [ 39 ].…”

Dosimetry Support of the Ukrainian-American Case-control Study of Leukemia and Related Disorders Among Chornobyl Cleanup Workers

“…The reliability and validity of the official doses depend on the time period considered and the type of work performed (Ilyin 1995; Chumak 2007; Bouville and Kryuchkov 2014). Reviews of official doses have revealed their possible bias and low accuracy, to degrees strongly correlated with the affiliation of the cleanup worker and, therefore, the type of dosimetric monitoring received at the time of cleanup (Chumak 2007).…”

Analysis of mortality in a pooled cohort of Canadian and German uranium processing workers with no mining experience

“…Uranium processing workers also come in contact with other types of radiation (e.g., gamma-ray, long-lived radionuclides from uranium ore dust) and non-radioactive (e.g., fine or silica dust) exposures from the ore dust, but less to RDP exposures, typical for uranium underground miners. Average annual effective radiation doses in this group have been reported at 10 millisievert (mSv) compared to <5 mSv for other workers of the fuel cycle (Bouville and Kryuchkov 2014 ). Several studies reported substantially higher cumulative lifetime occupational gamma-ray exposures for uranium processing workers (Kreuzer et al 2015 ; Zablotska et al 2013 ) compared to external radiation exposures of nuclear reactor workers (Cardis et al 2007 ; Muirhead et al 2009 ).…”