The strategy for the treatment of the Hanford Site tank wastes involves water and caustic washing of the tank waste sludge to reduce sludge mass and the corresponding maSs of high-level waste (HLW) glass that will be generated by the Waste Treatment and Immobilization Plant (WTP). During fiscal year (FY) 2003, CH2M HILL Hanford Group, Inc. (CH2M HILL) developed revised water wash and caustic leach factors for chromium (RPP-10222) and aluminum (RPP-11079) to estimate the waste treatment behavior of the tank waste compositions. Subsequently, the US. Department of Energy, Office of River Protection (OW) requested that CH2M HILL evaluate the potential impacts to the HLW glass mass due to these revised water wash and caustic leach factors. The ORP plans to use the results of this study in conjunction with separate information regarding the process impacts of implementing oxidative leaching at the WTP to determine whether oxidative leaching is adequate to mitigate potential increases in HLW glass production or whether additional strategies are required. The purpose of this sensitivity study of immobilized HLW glass mass to chromium and aluminum partitioning assumptions was to: identify the impacts of the revised water wash and caustic leach factors for chromium and aluminum on the mass of HLW glass; understand the effect of oxidative leaching on the mass of HLW glass; identify the major influences for HLW glass mass and waste blending; characterize the degree of pretreatment (water washing, caustic leaching, and oxidative leaching) assumed for different source tanks; and identify candidate tanks for opportunistic sampling and testing to confirm the inventory and better understand the behavior of chromium during retrieval, staging, and subsequent processing.
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