RECONSTRUCTION OF RADIONUCLIDE RELEASES FROM THE HANFORD SITE, 1944-1972

Historic releases of key radionuclides were estimated as a first step in determining the radiation doses that resulted from Hanford Site ope rations. The Hanford Site was built in southcentral Washington State d uring World War II to provide plutonium for the U.S. nuclear weapons p rogram. As part of the Hanford Environmental Dose Reconstruction (HEDR ) Project, releases to the Columbia River of Na-24, P-32, Sc-46, Cr-51 , Mn-56, Zn-65, Ga-72, As-76, Y-90, I-131, Np-239, and nonvolatile gro ss beta activity from operation of eight Hanford single-pass productio n reactors were estimated. Releases of Sr-90, Ru-103, Ru-106, I-131, C e-144, and Pu-239 to the atmosphere from operation of chemical separat ion facilities were also estimated. These radionuclides and the atmosp heric and Columbia River pathways were selected for study because scop ing studies showed them to be the largest contributors to dose from Ha nford operations. The highest doses resulted from releases to the atmo sphere of I-131 from chemical separations plants in the pre-1950 perio d. Prior to 1950, the technology for limiting iodine releases had not been developed. Hence, a very detailed reconstruction of the hourly I- 131 release history was achieved for 1944-1949 using Monte Carlo metho ds. Atmospheric releases of the other radionuclides were estimated on a monthly basis for 1944-1972 using deterministic calculations. Monthl y releases to the Columbia River for 1944-1971 were based on Monte Car lo methods.