An updated cost study for enhanced sludge washing of radioactive waste

Abstract

INTRODUCTIONThere exists approximately 100 million gallons of radioactive waste in underground storage tanks (USTs) at Department of Energy (DOE) sites across the United States. Approximately 54 million gallons are stored at the Hanford Site. The DOE is responsible for immobilization and permanent disposal of this tank waste. The Hanford tank waste is currently classified as high-level waste (HLW). While low-level waste (LLW) can generally be disposed of subsurface on-site, HLW must be disposed of in an underground repository such as that planned for Yucca Mountain. Since LLW disposal is obviously much less expensive than HLW, the plan for remediation at Hanford is to separate the UST waste into a small volume of HLW and a large volume of LLW.Of the 54 million gallons of UST waste at Hanford, approximately 20 volume-percent is solids-based, consisting primarily of sludge, and

An Updated Cost Study for Enhanced Sludge Washing of Radioactive Waste

“…It demonstrates an extremely favorable rate of return on investment as estimated in an earlier study (DeMuth & Shieh, 1999). …”

“…Process parameters evaluated and/or optimized include time, temperature, caustic (NaOH) concentration, and additives targeting dissolution of specific species such as chromium.The time and temperature affect both the capital and operating costs. Excess caustic concentrations can produce excessive radionuclide dissolution, which can contaminate the separated aluminum, sodium, phosphorus, and chromium.Therefore, ESW development has been focused on determining the optimum time, temperature, and caustic concentration for multiple waste types.The author has conducted three past ESW cost studies for the Hanford Site.The first study (DeMuth, 1997) was based upon the original Westinghouse tank waste remediation system (TWRS) flow sheet, which included the ESW separation factors of 1995 (Orme et al, 1995).The second study (DeMuth & Williams, 1997) was a revised version of the first based upon the initial Westinghouse Privatization flow sheet, which included the ESW separation factors of 1996 (Orme et al, 1996).The third study (DeMuth & Shieh, 1999) was a revised version of the second based upon the initial Tank Waste Remediation System Operation and Utilization Plan, which included Colton's 1997 ESW separation factors (Kirkbride et al, 1997).The first study determined the poten- …”

Partitioning of U(VI) and Eu(III) between Acidic Aqueous Al(NO3)3and Tributyl Phosphate in n‐Dodecane

“…Solutions of HNO 3 were prepared by mass using Fisher Scientific concentrated (15.8 M) HNO 3 solution. Solutions of K 2 CrO 4 , Al(NO 3 ) 3 and NaNO 3 were prepared by mass using analytical grade J.T. Baker solids.…”

“…This study was designed to encompass a wide variety of aqueous phase conditions that could be encountered during HNO 3 …”

“…Two of the most problematic non-radioactive elements that plague the tank sludge remediation efforts are Al and Cr. Removing Al and Cr solids from the sludge for separate disposal as low-level waste would greatly reduce the volume, and consequently the overall cost for the HLW sludge disposal operations (3). The investigation of various Al and Cr removal processes has been the subject of research for the past decade.…”