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Radiation Exposure for Uranium Industry Workers

(work in progress - last updated 2 Sep 2010)

Contents:

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Workers: Standards

The applicable radiation dose standard for workers is 20 mSv/a (averaged over 5 years), and the fatal cancer risk is 0.04 per Sv, according to [ICRP60].

Exposure to 20 mSv/a over a work life of 40 years results in an excess lifetime fatal cancer risk of 3.2% (1 : 31).


Workers at Uranium Mine

Source Term

The radon emanation rate from the Jabiluka ore deposit in Australia was determined at 15 Bq/m2·s per %U3O8 (18 Bq/m2·s per %U) ore grade [Sonter2000]. For secular equilibrium of the uranium series nuclides, this corresponds to 0.142 Bq/m2·s per BqRa-226/g.

Exposure of Miners

Typical individual doses vary within the range of 3 - 20 mSv/a (avg. 4.45 mSv/a) for underground miners, and within the range of 1 - 5 mSv/a (avg. 1.56 mSv/a) for open pit miners, with an average of 4.4 mSv/a over all uranium miners.
The collective dose for all 260,000 underground uranium miners worldwide is estimated at 1140 man-Sv/a, and for all 2500 open pit uranium miners at 3.76 man-Sv/a. This corresponds to 25.9 man-Sv per 1000 t uranium mined underground, and to 0.258 man-Sv per 1000 t uranium mined in open pits, with an average of 20 man-Sv per 1000 t for all uranium mined. [UNSCEAR1993] for 1985-1989
The expected number of fatal cancers in all uranium miners is 44 per year, or 0.8 per 1000 t uranium mined.

(see also Health Impacts for Uranium Miners · Sample Calculations)


Workers at Uranium mill

Source Term

Exposure of mill workers

Typical individual doses for uranium mill workers vary within the range of 0.1 - 13 mSv/a (avg. 6.3 mSv/a).
The collective dose for all 18,000 uranium mill workers worldwide is estimated at 116 man-Sv/a; this corresponds to 2.01 man-Sv per 1000 t uranium extracted. [UNSCEAR1993] for 1985-1989
The expected number of fatal cancers in all uranium mill workers is 4.64 per year, or 0.08 per 1000 t uranium extracted.


Workers at Heavy Water Reactor Fuel Plant

For use in heavy water reactors (HWR), the uranium ore concentrate is refined (purified) and converted to UO2. Then it is formed into pellets and filled into fuel rods. The fuel rods are bundeled into fuel elements.

Source Term

Exposure of HWR fuel fabrication workers

The average individual dose for a heavy water reactor fuel fabrication worker is 1.67 mSv/a. The collective dose for all 1140 HWR fuel fabrication workers worldwide is estimated at 1.9 man-Sv/a; this corresponds to 1.21 man-Sv per 1000 t fuel fabricated. [UNSCEAR1993] for 1985-1989
The expected number of fatal cancers in all HWR fuel workers is 0.076 per year, or 0.048 per 1000 t fuel fabricated.


Workers at Magnox Reactor Fuel Plant

For use in Magnox reactors, the uranium ore concentrate is refined (purified) and converted to uranium metal. This is formed into fuel rods. The fuel rods are cladded and bundeled into fuel elements.

Source Term

Exposure of Magnox fuel fabrication workers

The average individual dose for a Magnox fuel fabrication worker is 3.12 mSv/a. The collective dose for all 1,110 Magnox fuel fabrication workers in the United Kingdom is estimated at 3.48 man-Sv/a; this corresponds to 4.29 man-Sv per 1000 t fuel fabricated. [UNSCEAR1993] for 1985-1989
The expected number of fatal cancers in all UK Magnox fuel workers is 0.14 per year, or 0.17 per 1000 t fuel fabricated.


Workers at Uranium Conversion and Enrichment Plant

For use in light water reactors, the uranium ore concentrate is refined (purified) and converted to uranium hexafluoride (UF6) in a conversion plant.
At the enrichment plant, the concentration of the fissile uranium isotope U-235 in the uranium hexafluoride is raised from its natural grade of 0.711% to the range of 3 - 5%.

Source Term

Additional hazards exist, if not only uranium of natural origin is processed, but also uranium recovered from reprocessing of spent nuclear fuel. The latter uranium is contaminated with radioactive transuranics and fission products.
The Paducah (Kentucky) uranium enrichment plant, for example, processed recycled uranium between 1953 and 1976. Paducah received approximately 90,000 metric tonnes of recycled uranium containing an estimated 3.6 ppb of plutonium-239, 0.2 ppm of neptunium-237 and 7.3 ppm of technetium-99. The majority of the plutonium and neptunium was separated out as waste during the initial chemical conversion to uranium hexafluoride. Because of this, only a fraction (0.03%) of the plutonium contamination was actually introduced to the gaseous diffusion cascade. (DOE Press Release Sep 29, 1999 external link)
Moreover, uranium recycled from spent fuel contains several artificial uranium isotopes, such as U-232, U-233, U-236, and U-237. Uranium-232 is of special concern, since some of its decay products are strong gamma emitters (in particular thallium-208).

Exposure of conversion and enrichment workers

The average individual dose for an uranium enrichment worker is 0.08 mSv/a. The collective dose for the 5,000 enrichment workers for whom data is reported is estimated at 0.43 man-Sv/a. [UNSCEAR1993] for 1985-1989
The average individual dose for cylinder yard workers at three U.S. enrichment plants ranged between 0.16 - 1.96 mSv/a during the years 1990-1995 [DOE1999] p.3-15/32/51.


Workers at Light Water Reactor Fuel Fabrication Facilities

In the fabrication plant for light water reactor fuel, the enriched uranium hexafluoride is converted to UO2. Then it is formed into pellets and filled into fuel rods. The fuel rods are bundeled into fuel elements.

Source Term

Exposure of LWR fuel fabrication workers

The average individual dose for a light water reactor (LWR) fuel fabrication worker is 0.45 mSv/a. The collective dose for all 24,000 LWR fuel fabrication workers worldwide is estimated at 11 man-Sv/a; this corresponds to 1.6 man-Sv per 1000 t fuel fabricated. [UNSCEAR1993] for 1985-1989
The expected number of fatal cancers in all LWR fuel workers is 0.44 per year, or 0.064 per 1000 t fuel fabricated.


Workers: Summary

Workers' Dose Summary
no. of workersavg. individual dose
[mSv/a]
collective dose
[man-Sv/a]
all uranium miners260,0004.41,100
uranium mill workers18,0006.3116
HWR fuel facility workers1,1401.671.9
Magnox fuel facility workers1,1103.123.48
enrichment workers5,0000.080.43
LWR fuel facility workers24,0000.4511
AGR fuel facility workers1,8502.975.51
TOTAL311,1003.981,238
[UNSCEAR1993] for 1985-1989 (minor inconsistencies in ref.)

Workers' Risk Summary
no. of workersexcess lifetime cancer risk*collective risk
[fatalities per year]
all uranium miners260,0000.7%1 : 14244
uranium mill workers18,0001.01%1 : 994.64
HWR fuel facility workers1,1400.27%1 : 3740.076
Magnox fuel facility workers1,1100.5%1 : 2000.14
enrichment workers5,0000.013%1 : 78120.017
LWR fuel facility workers24,0000.072%1 : 13890.44
AGR fuel facility workers1,8500.48%1 : 2100.22
TOTAL311,1000.64%1 : 15649.5
* based on 40 working years
based on [UNSCEAR1993] for 1985-1989, using risk factor of 0.04 per Sv


References

[Bailey1975] Uranium handling at the Oak Ridge gaseous diffusion plant, by J. C. Bailey, K-L-6346, 1975

[DOE1999] Final Programmatic Environmental Impact Statement for Alternative Strategies for the Long-Term Management and Use of Depleted Uranium Hexafluoride, DOE-EIS-0269, U.S. DOE, Germantown MD, April 1999
> Download PEIS from ANL external link or DOE EH external link

[IAEA1994] Interim Guidance for the Safe Transport of Reprocessed Uranium external link, IAEA-TECDOC-750, IAEA, Vienna, June 1994, 68 pages (3.2M PDF)

[ICRP60] 1990 Recommendations of the International Commission on Radiological Protection, ICRP external link Publication 60, Oxford 1991

[Neghabian1991] Verwendung von wiederaufgearbeitetem Uran und von abgereichertem Uran, von A.R. Neghabian, H.J. Becker, A. Baran, H.-W. Binzel, Der Bundesminister für Umwelt, Naturschutz und Reaktorsicherheit external link (Hg.), Schriftenreihe Reaktorsicherheit und Strahlenschutz, BMU-1992-332, November 1991, 186 S.

[NUREG-0713] Occupational Radiation Exposure at Commercial Nuclear Power Reactors and Other Facilities external link, Annual Reports, NUREG-0713, U.S. Nuclear Regulatory Commission

[NUREG/CR-4884] Interpretation of Bioassay Measurements external link, NUREG/CR-4884, July 1987 (38.6MB PDF)

[Sonter2000] Underground Radiation Studies and Observations in the Jabiluka Ore Access Drive, by Mark J Sonter, Australian Radiation Protection Society, ARPS25 Abstracts external link, 2000

[UNSCEAR1993] Sources and Effects of Ionizing Radiation, United Nations Scientific Committee on the Effects of Atomic Radiation, UNSCEAR 1993 Report to the General Assembly, with Scientific Annexes, United Nations external link, New York, 1993, 922 p.

[Urenco2002] Urananreicherungsanlage Gronau. Kurzbeschreibung des Endausbaus und der voraussichtlichen Auswirkungen auf die Umgebung. Stand: Dezember 2002, Urenco Deutschland

see also:
U.S. DOE: DOE Standard - Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities, August 2000 / October 2000 external link (1.2M PDF)

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