The radiological impact of the 2000 Hanford Fire (24-Command Fire)

Abstract

The range fire at the Hanford facility in late June 2000 coupled with the fire at Los Alamos during the same year have raised a number of questions about the potential migration and/or transport of radioactive materials off U.S. nuclear sites into more populated areas. This paper examines the radiological impact of the 24-Command Fire, which occurred on the Hanford Site in late June 2000. Several different approaches are compared against each other to determine the validity of the results. The approaches include physical calculations from collected data as well as estimates from current transport and diffusion software. The analysis begins with the estimation of release. There are sufficient data on the concentrations of radionuclides in the most contaminated areas of the Hanford Site, but very little on the land in between. Once soil concentrations were determined, resuspension factors were applied to estimate releases of material from these areas. A Hanford-specific diffusion and dispersion program, a dose assessment program, and a calculation by hand were used to determine the estimated transport of material to areas populated by the general public. These results are compared against each other as well as the air monitoring results obtained and reported by the United States Environmental Protection Agency and the Washington State Department of Health. Air concentrations from all three methods were used to calculate the associated doses and risks to individuals in these areas. From the analyses, the radiological impact of the fire was determined to be minimal. The ensuing wind events, resuspending particulate matter from the contaminated areas burned during the fire, resulted in a committed effective dose of approximately 10 []Sv (0.01 mrem) from the inhalation of contaminated air. This dose is insignificant when compared to the 360 mrem per year average dose of a member of the general public from indoor and outdoor sources of background radiation. The ingestion pathway was analyzed but found to contribute less than 2 Bq yr⁻¹ for the most important foodstuffs: vegetables and fruits.