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Dose reconstruction for plutonium-239 intakes at the Rocky Flats Plant

by Caleigh E Samuels, Richard W Leggett
Publication Type
Journal Name
International Journal of Radiation Biology
Publication Date
Page Numbers
1841 to 1852

The Rocky Flats (RF) Plant was a weapons manufacturing facility located near Denver, Colorado which operated from the early 1950s to 1989. Its primary missions were production of plutonium (Pu) pits (cores) for thermonuclear weapons and processing of retired weapons and residues for Pu recovery. RF workers were potentially exposed to a variety of radionuclides, the most important internal emitter being 239Pu, the dominant Pu isotope contained in the pits. This paper describes the methods and summarizes results of 239Pu dose reconstructions for 4499 RF workers. RF was a unique site in that time-dependent measurements of 239Pu in lungs were coupled with urinary 239Pu measurements for many of the workers. This provided higher confidence in reconstructed 239Pu doses than can be gained from urinary data alone. Urinary excretion and lung retention data for most 239Pu intakes could be fit reasonably well by some mixture of Pu dioxide and a moderately soluble material. For some workers, however, better fits were obtained by application of other ICRP absorption types for plutonium including Type S, 239Pu nitrate, pure 239Pu dioxide, and occasionally Type F material, or by assuming intake via a wound. Largest doses were to the lungs. Fifty-year committed equivalent lung dose was in the range of 0.5-1 Sv for 275 workers, 1-5 Sv for 115 workers and greater than 5 Sv for 12 workers.