Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
早野 明; 青柳 和平; 村上 裕晃; 木村 駿
Proceedings of 2025 International High Level Radioactive Waste Management Conference (IHLRWM 2025) (Internet), p.8 - 11, 2025/11
An empirical approach is being implemented at the Horonobe Underground Research Laboratory in Neogene sedimentary rocks to integrate technologies for optimizing the layout of disposal tunnels and pits. Key evaluation items include tunnel and pit mechanical stability and spacing, both influenced by the excavation damaged zone. Water inflow is also evaluated to ensure the constructability of excavation and buffer placement. Prediction methods for geological and hydrogeological conditions have been developed, and in situ investigations are underway in the 500 m Niches Nos. 8 and 9. Sealing measures such as tunnel backfilling and hydraulic plug installation are essential for closure and should be transferable to other rock types. Accordingly, an in situ construction test is being prepared in the 350 m Niche No. 6, supported by site investigations and laboratory and feasibility tests of construction methods and materials. A full scale construction experiment is scheduled for the second half of 2026.
木村 駿; 早野 明; 小野 誠*
Proceedings of 2025 International High Level Radioactive Waste Management Conference (IHLRWM 2025) (Internet), p.12 - 15, 2025/11
Excavation damaged zone (EDZ), resulting from tunneling and stress redistribution, has the potential to increase hydraulic conductivity by creating new fractures and opening existing ones, and to act as a short-circuit flow path between the repository and ground surface. In the closure phase of the repository for geological disposal in Japan, the backfilling of tunnels and the installation of hydraulic plugs are considered in order to provide the safety function of reducing radionuclide migration by avoiding flow short-circuits through and around the tunnels. Japan Atomic Energy Agency initiated a full-scale construction experiment at Horonobe URL. The objective of this experiment is to develop and demonstrate the design and construction technology of the hydraulic plug for sedimentary rock. The experiment is concerned with the characterization of EDZ in relation to its mechanical and hydraulic properties, the material design of the tunnel backfill and hydraulic plug, and the development of the construction technology. This report represents the consideration of the hydraulic plug shape employing three-dimensional analysis of the excavation of the tunnel and notch.
山本 章夫*; 遠藤 知弘*; 渡邉 友章
Transactions of the American Nuclear Society, 133(1), p.698 - 701, 2025/11
A sensitivity analysis was conducted to evaluate the impact of nuclide-wise self-shielding and scattering matrix treatments in a detailed burnup calculation involving more than 4,000 nuclides. The analysis was performed using a newly developed neutronics analysis code, GenesisRPC, based on the neutron transport code GENESIS for two- and three-dimensional geometries. The results, obtained for UO
and MOX fuel systems, indicate that for nuclides with number densities below 10
[1/barn/cm], the effects of self-shielding factors and the P0 (isotropic) scattering matrix are negligible. Additionally, the impact of the Pn (anisotropic) scattering matrix was found to be insignificant for nuclides with number densities below 10
[1/barn/cm] in the present calculation conditions, suggesting that only nuclides with high initial concentrations need to be considered.
岡本 孝司
no journal, ,
福島第一原子力発電所事故に対するCLADSの研究開発について、廃炉に資する取り組みを中心に報告する。
