Requirement of decontamination factor for near-surface disposal of PEACER wastes

A pyrochemical process has been introduced and utilized so that the transmutation of spent PWR fuel in PEACER can produce mainly low- and intermediate-level waste for near-surface disposal. Major radioactive nuclides from PEACER pyroprocessing are composed of transuranic element (TRU) and long-lived fission product (LLFP). In this study, the requirement for the final waste from PEACER is evaluated based on the methodology for establishment of waste acceptance criteria. Also, sensitivity analysis for several input parameters is conducted in order to determine acceptable decontamination factor (DF) and LLFP removal efficiency and to find out input parameter that extremely has an effect on DF. As a result of the study, LLFP removal efficiency, especially Sr-90 and Tc-99, is proved to be a major nuclide which contributes to annual dose by human intrusion scenario rather than TRU DF. To satisfy the acceptance criteria, DF for TRU and removal efficiency for LLFP have to be achieved more than 104 and 96%, respectively. Besides, because of the relative short half-life of Sr-90, the increasing of the institutional control period is recommended for the most important input parameter to determine DF.