Radiological Safety Assessment for Deep Geological Disposal of High-Level Radioactive Waste

초록

The radiological safety assessment of high-level radioactive waste (HLW) deep geological disposal facilities is essential for ensuring responsible and sustainable nuclear waste management. This study aims to develop a radionuclide transport model using the GoldSim code to simulate radionuclide release from spent nuclear fuel, facilitating the safety assessment of HLW deep geological disposal. Two types of reference South Korea's pressurized water reactor spent nuclear fuels (PWR SNFs), namely PLUS7 and ACE7, were utilized to calculate the radioactive inventory. Due to the absence of a high-level waste disposal site in Korea, conservative input parameter values were adopted from the relevant literature for the conceptual modeling component. The radiological safety assessment indicated that the reference Korea's PWR SNFs did not exceed 1 mSv/year, even lower than South Korea's natural background rate (2.4 mSv/year). Both C-14 and I-129 were identified as the primary contributors to the total exposure dose compared to other radionuclides, and a sensitivity analysis was conducted for these radionuclides. The investigation into the influence of distribution coefficients (Kd) of C-14 and I-129 in the buffer and the host rock revealed that the radiological peak dose rate is more affected by the buffer than the host rock. Buffer sorption in the near field was found to significantly reduce the equivalent exposure dose. Overall, this study's findings can inform the establishment of conditions for deep geological disposal and provide quantitative analysis methods using GoldSim for the crucial long-term safety evaluation of a high-level waste repository.

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