Human dose assessment for the radionuclides {sup 90}Sr and {sup 90}Y at TA-35 SWMU 35-003 (r) and Ten Site Canyon

This report gives an estimate of the radiological dose to an individual living on or working at a site contaminated with strontium-90 ({sup 90}Sr) and yttrium-90 ({sup 90}Y). The site consists of a small receiving canyon that drains into Ten-Site Canyon at the eastern end of Los Alamos National Laboratory`s technical area 35 (TA-35). Between 1951 and 1963 a wastewater treatment facility located at TA-35 discharged water containing {sup 90}Sr and {sup 90}Y to this receiving canyon. The authors used the RESRAD computer code to calculate the dose to an on-site individual, based on two exposure scenarios: (1) a person working at the site for eight hours a day, five days a week, for twenty-five years and (2) a farmer living at the site twenty four hours a day, seven days a week, for thirty years. The exposure pathways considered were direct exposure to external radiation; inhalation of contaminated dusts; and ingestion of plants, water, and soil. The authors found that the maximum estimated dose rates were 1 and 21 mrem y{sup {minus}1} for the worker and farmer scenarios respectively. The authors have concluded that the value for the worker scenario is well below the DOE dose limit of 100 mrem y{sup {minus}1} but the farmer is overexposed