Waste Preparation and Transport Chemistry: Results of the FY 2001 Studies

Hunt, R.D.

Oak Ridge National Laboratory

关键词: Evaporators;    Aluminium;    12 Management Of Radioactive Wastes, And Non-Radioactive Wastes From Nuclear Facilities;    Dissolution;    Wastes;   

DOI  :  10.2172/814305
RP-ID  :  ORNL/TM-2001/289
RP-ID  :  AC05-00OR22725
RP-ID  :  814305

美国|英语

来源: UNT Digital Library

【 摘 要 】

During FY 2001, tank farm operations at Hanford and the Savannah River Site (SRS) continued to be negatively impacted by the unintended formation of solids. At Hanford, the primary solids formation problem involves a series of plugged pipes and pumps during the saltwell pumping activities of the interim stabilization program. For example, transfers of tank S-102 waste were suspended due to a plugged pipeline or a mechanical problem with the transfer pump. The replacement pump then failed within 2 weeks. In contrast, since full-scale waste remediation activities such as vitrification were initiated, the SRS has encountered a wider range of problems due to unwanted solids. The 2H evaporator system was shut down because of the formation of aluminosilicate deposits with enriched uranium in the evaporator pot. While high concentrations of aluminum are expected in the tank waste due to previous canyon operations, the primary source of silicon is the recycle stream from the vitrifier. While solids formation can be expected when waste streams are combined, the formation of the aluminosilicate deposits required an elevated temperature within the evaporator. The shutdown of the 2H evaporator led to a severe shortage of tank space. Therefore, the SRS tank farm was forced to transfer highly concentrated waste, which led to a plugged transfer pump in tank 32. For each of the proposed cesium removal technologies for the SRS, unwanted solids formation occurred during the large laboratory-scale tests prior to the final selection of the solvent extraction process. It can be expected that further problems will be encountered as more unit operations of the remediation effort are deployed and as more waste streams are combined. Since these problems have already led to costly schedule delays, the tank farm operators at both sites have identified the prevention of solids formation as a high-priority need. In response to this need, the Tank Focus Area has assembled a team of researchers of researchers from AEA Technology, Florida International University (FIU), Fluor Hanford, Mississippi State University (MSU), Oak Ridge National Laboratory (ORNL), and Savannah River Technology Center (SRTC) to evaluate various aspects of the waste preparation and transport chemistry. The majority of this effort was focused on saltcake dissolution and saltwell pumping. The results of the AEA Technology, FIU, and MSU studies of saltcake dissolution and slurry transfers for Hanford are discussed in detail in a companion report prepared by T. D. Welch in 2001 (ORNIJTM-2001097). Staff members at Fluor Hanford have continued to conduct saltcake dissolution tests on actual tank waste (documented in reports prepared by D. L. Herting in 2000 and 2001). It should be noted that full-scale saltcake dissolution at Hanford is scheduled to begin in FY 2002. While the Hanford effort is focused on the transfer of waste from one tank to another, the objective of the SRTC study is the formation of aluminosilicates at elevated temperatures, which are present in the waste evaporator.