METHODOLOGY FOR DETERMINATION OF RADIOASSAY PROPERTIES FOR RH-TRU WASTE

decommissioning activities will generate approximately 25 cubic meters of remote-handled transuranic (RH-TRU) wastes, which are planned for ultimate disposal at the Waste Isolation Pilot Plant (WIPP). For WIPP disposal, the isotopic inventory of the waste must be characterized to demonstrate compliance with applicable limits. The BCLDP has developed a methodology that combines limited assay, knowledge of the processes generating the waste, and a dose/weight-to-curie evaluation to determine the isotopic characterization of the waste. The BCLDP methodology determines the isotopic content for an identified TRU waste stream by a combination of (1) representative waste stream sample analyses, (2) application of Oak Ridge Isotope Generation and Depletion (ORIGEN2) code values for isotopes expected in spent nuclear fuel but not represented by the sample analyses, and (3) assessment of cesium (Cs)-137 content of a payload container based on external radiation field measurements and calculation of TRU isotopic content using a ratio of radionuclides based on known Cs-137 content. The measured isotopic distribution (gamma emitters) of a waste stream is combined with values determined through the conservative application of the ORIGEN2 to account for all isotopes. External dose rates for 1 millicurie of an isotopic mix are modeled for different packaging configurations