Thorium processing

A more constrained opportunity for nitrate bioremediation arose at the US-DoE Weldon Spring Site near St. Louis, Missouri. This site had been a uranium and thorium processing faciUty, and treatment of the metal had involved nitric acid. The wastestream, known as raffinate, was discharged to surface inpoundments and neutralized with lime to precipitate the metals. Two pits had nitrate levels that requited treatment before discharge, but heavy rains in 1993 threatened to cause the pits to overflow. Bioremediation by the addition of calcium acetate as a carbon source successfully treated more than 19 million liters of water at a reasonable cost (75). 

United States Companies with Thorium Processing and Fabricating Capacity s... 

Two epidemiology studies have examined mortality among thorium workers neither found significant excess mortality. The standard mortality ratio (SMR) for all causes of death in a cohort of 3039 male workers in a thorium processing plant was 1.05 in comparison to United States white males (Polednak et al. 1983). The estimated radiation levels to the workers for inhalation intake ranged from 0.003-0.192 nCi/m (0.001-0.007 Bq/m ) for a period of 1-33 years. No evidence of overt industrial disease was found in a cohort of 84 workers at a thorium refinery exposed to <0.045-450 nCi/m (<0.002-0.02 Bq/m ) for <1-20 years (Albert et al. 1955). In both studies, the workers were exposed to other toxic compounds (uranium dust) as well as other radioactive materials (thoron, uranium daughters, thorium daughters, cerium). 

Davis MW. 1985. Radiological significance of thorium processing in manufacturing. Report. INFO-0150. 

Jensen L, Regan G, Goranson S, et al. 1984. Ambient monitoring of airborne radioactivity near a former thorium processing plant. Health Phys 46 1021-1033. 

Kotrappa P, Bhanti DP, Menon VB, et al. 1976. Assessment of airborne hazards in the thorium processing industry. Am Ind Hyg Assoc J 37 613-616. 

PolednakAP, StehneyAF, Lucas HF. 1983. Mortality among male workers at a thorium-processing plant. Health Phys44(Suppl 1) 239-251. 

Management and disposal of most uranium or thorium mill tailings are governed by the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA, 1978). This Act is concerned with the control and stabilization of mill tailings for protection of public health and the environment. It addresses (1) remedial actions at inactive uranium or thorium processing sites or on properties in the vicinity of... 

Design fuel bumup is between 60,000 and 100,000 MWd/MT, instead of a few hundred in the irradiated thorium processed at Savannah River and Hanford. This causes uranium and fission-product concentrations and fission-product radiation levels to be much higher than in the inadiated thorium processed at Savannah River and Hanford. 

Thus, for Thorex, the variable processing charge is considered to be 3.00/kg of thorium processed, plus 0.50/g total uranium processed (U highly enriched in -f plus 0.33/liter of D2O recovered. 

---