Alpha waste, retrievable

Approximately 300 kg of dried metal hydroxide solids would be produced per month from decontamination of 120 m3 of PRF salt waste. These solids could be drummed and stored at Hanford as a retrievable alpha waste. Techniques for incorporating the metal hydroxide solids in an immobile borosilicate glass have been developed also. (12)... 

TRU are those containing isotopes, like 241Am and 243Am, that follow uranium in the periodic table and whose half-lives are >20 years. If their level of activity was more than 100 nanocuries of alpha-emitters per gram of waste material (up from 10 nanocuries/g in 1982), the waste could be disposed of by shallow burial. Otherwise, the waste had to be placed in retrievable storage for eventual transfer to a permanent repository. TRUs generally have low levels of radioactivity, generate very little heat, and can be handled by ordinary means without remote control (Eisenbud 1987 Murray 1994). 

In normal operation, the PRF generates about 120 m3 of salt waste solution per month. Currently, this waste solution is made alkaline and routed to underground storage tanks where it mixes with other Hanford defense waste liquors. An alternative waste treatment scheme is desirable to avoid converting large volumes of non-actinide waste to retrievable actinide waste (>10 nCi alpha activity/g) and also to help make the PRF independent of future tank farm management operations. 

Also resulting from reprocessing are the lower-activity wastes that are contaminated with transuranic elements (TRU waste). These wastes are defined as containing 100 nanocuries of alpha-emitting transuranic isotopes (with half-lives >20 years) per gram of waste. Over 60,000 m are stored retrievably at DOE sites and are destined for disposal at the Waste Isolation Pilot Plant in New Mexico (Aheame 1997). The estimated cost of remediation and restoration programs in the DOE complex during the next few decades is on the order of 200 billion dollars (Crowley 1997). 

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