Optimization of disposal method and scenario to Reduce High Level Waste Volume and Repository Footprint for HTGR

• Published in: Annals of nuclear energy 2018-06, Vol.116, p.224-234
• Main Authors: Fukaya, Yuji, Goto, Minoru, Ohashi, Hirofumi, Nishihara, Tetsuo, Tsubata, Yasuhiro, Matsumura, Tatsuro
• Format: Article
• Language: English
• Subjects: Footprint; Four-group partitioning; GTHTR300; High burn-up; HLW; HTGR
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/j.anucene.2018.02.031

•Canister numbers and its footprint of disposal processes were evaluated in an HTGR.•Waste reduction was optimized by horizontal emplacement and proper disposal scenario.•Footprint was reduced by 50% in direct disposal and 80% in disposal with reprocessing.•Four-group partitioning technology reduced the footprint by 90% from reference. To reduce volume of High Level Waste (HLW) and the footprint in the geological repository of a High Temperature Gas-cooled Reactor (HTGR), this study optimizes the disposal method and scenario of the HLW. By virtue of high burn-up, high thermal efficiency and pin-in-block type fuel, the HTGR more effectively reduces the HLW volume and its footprint than those of Light Water Reactor (LWR) in our previous study. In this study, the disposal method and scenario are optimized. To optimize the disposal method, the geological repository layout is the horizontal emplacement based on the KBS-3H concept, rather than the vertical emplacement based on the KBS-3V concept adopted in our previous study. In comparison with the earlier study, the horizontal emplacement reduced the repository footprint in direct disposal by 20% in the same scenario. By extending the cooling time by 40 years before disposal, the footprint was reduced by 50%. In disposal with reprocessing, extending cooling time by 1.5 years between discharge and reprocessing reduced the number of canister generated by 20%. Extending the cooling time by 40 years pre-disposal reduced the footprint per unit of electricity generation by 80%. Moreover, by employing four-group partitioning technology without transmutation, the footprint can be reduced by 90% with a cooling time of 150 years.