REVISED GUIDELINES FOR USING CELLULOSE DEGRADATION PRODUCT-IMPACTED KD VALUES FOR PERFORMANCE ASSESSMENTS AND COMPOSITE ANALYSES

Kaplan, D.

关键词: AR FACILITIES;    ANIONS;    CARBON;    CATIONS;    CELLULOSE;    IODINE;    PERFORMANCE;    RADIOACTIVE WASTES;    RADIOISOTOPES;    RECOMMENDATIONS;    SAVANNAH RIVER PLANT;    SEDIMENTS;    SORPTION;    TECHNETIUM;    WASTES;    WOOD;   

DOI  :  10.2172/1039993
RP-ID  :  SRNL-STI-2012-00138
PID  :  OSTI ID: 1039993
Others  :  TRN: US1202522

美国|英语

来源: SciTech Connect

【 摘 要 】

Cellulosic materials include wood, paper, rags, and cardboard products. These materials are co-disposed with radiological waste at the Savannah River Site's (SRS) E-Area Low-Level Waste Facility (ELLWF). Cellulosic materials readily degrade in the environment to form cellulose degradation products (CDP) that will partition to the sediment or remain mobile in the groundwater. Savannah River National Lab (SRNL) has conducted studies to estimate the impact of CDP on radionuclide sorption to SRS sediments (Kd values). It was found that CDP impact on radionuclide sorption varies with radionuclide and CDP concentration. Furthermore, it was found that the amount of carbon (C) in the system could increase or decrease Kd values with respect to the base case of when no CDP was added. Throughout the expected pH range of the ELLWF, a low concentration of CDP in the system would increase Kd values (because C would sorb to the sediment and provide more exchange sites for radionuclides to sorb), whereas greater concentrations of CDP ({ge}20 mg/L C) would decrease Kd values (because C would remain in solution and complex the radionuclide and not permit the radionuclide to sorb to the sediment). A review of >230 dissolved organic carbon (DOC) groundwater concentrations in the Old Radioactive Waste Burial Ground (ORWBG) at the SRS indicated that the average DOC concentration, a gross measure of CDP, was 5 mg/L C. At approximately this DOC concentration, the laboratory studies demonstrated that no anions (Tc, I, or Se) or cations (Ni, Sr, Ce, Eu, Zr, or Th) have decreased sorption in the presence of carbon (an analogue for CDP).