Long-term environmental assessment of waste from PyroGreen system

We have conducted a long-term environmental assessment of a geological repository for Intermediate Level Wastes (ILW) arising from PyroGreen processes that has been developed to decontaminate all HLW from the pyrochemical partitioning of spent nuclear fuels (SNF). PyroGreen process has been designed so that final ILW can meet conservative acceptance criteria such as one established for the Waste Isolation Pilot Plant (WIPP) in U.S.A. The nuclide inventory of final vitrified PyroGreen waste is calculated using ORIGEN 2.1 based on the design decontamination factor of PyroGreen processes applied to 18,171 metric tons of PWR SNF with 45 GWD/MTU burnup. Using GoldSim model, the environmental impact of ILW upon geological disposal at an intermediate depth. Among radioactive nuclides, Ra²²⁶, Rn²²² and Sn¹²⁶ are identified as key contributors to radiological dose for general public. The environmental impact of PyroGreen wastes satisfies the Korean dose limit of 0.1 mSv/year with sufficiently high margin. Sensitivity studies have shown that the predicted dose can vary significantly by distribution coefficient of Ra²²⁶ and Rn²²², solubility limit of Se⁷⁹. (authors)