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Comparison of Two Disposal Concepts for CANDU Spent Nuclear Fuels in Korea
- 언어ENG
- URLhttps://db.koreascholar.com/Article/Detail/429919
p.166
It is expected that around 576,000 bundles of CANDU spent nuclear fuels (SNF) will be generated from the four CANDU reactors located at the Wolsong site, according to the 2nd National Plan for the management of High-Level radioactive Waste (HLW). The CANDU SNFs are currently stored at the dry storage facilities at the Wolsong site. The authors proposed KRS+ geological disposal system consisting of two different concepts, Swedish KBS-3V type and Canadian NWMO type, for the final management of CANDU SNF. Both the concepts were designed based on the geological data obtained from the KURT (KAERI Underground Research Tunnel). The NWMO type is an in-room horizontal placement method. In this study, we try to determine the reference concept among the two proposed concepts at 500 meters below the ground surface. Assuming 10,000 tU of CANDU SNF and the KURT site, we design two engineered barrier systems, that is disposal canisters and buffers. The copper disposal canister is designed with a copper thickness of 10 mm based on a cold spray coating technique for both the disposal concepts. The domestic Ca-bentonite is used for the compact bentonite buffer with dry density of 1.6 g/cm3. Two concepts are compared in terms of safety, economics of the engineered barriers, and environment-friendliness. Because the same amounts of CANDU SNF are disposed of at the same depth, the differences in the disposal area are neglected. For the comparison in terms of safety, the corrosion lifetimes of the disposal canisters of two disposal systems are quantitatively calculated, and the capacities for retarding radionuclide releases of the compacted bentonite buffers are assessed. A computer tool developed by the authors is used in order to assess the lifetime of a disposal canister. In this study, the case that corrosion of a copper canister by sulfide from groundwater through intact buffer is analyzed. The sulfide concentration in groundwater is assumed to be 3 ppm. The most important safety function of buffer is to retard the radionuclide release. Twelve long-lived radionuclides are selected to compare the capacities for retarding the radionuclide transport through the buffer using an analytical solution. The retention time by an engineered barrier consisting of a disposal canister and a buffer is compared with twenty times the half-life of each radionuclide for both the disposal systems. The selected reference concept will be compared with the alternative geological concepts through a further study.
