Applicability study on the design method for the buffer material of a HLW repository

高レベル放射性廃棄物処分における緩衝材設計手法の適用性に関する検討

棚井 憲治 ; 内藤 守正 

Tanai, Kenji; Naito, Morimasa

The basic design flow for the Japanese reference Engineered Barrier System (EBS) and the associated disposal facility for high-level radioactive waste (HLW) was presented in the H12 report. This approach was appropriate to the boundary conditions at that time - defining a repository system that would allow feasibility of post-closure safety to be demonstrated for generic Japanese sites. Over the last decade such boundary conditions have changed dramatically as siting has now been initiated by an open call for volunteer communities to host this facility. The design process must now develop realistic and practical repository systems that can be tailored to specific locations and are described in sufficient detail that they can aid in the site selection process. Although it is clear that post-closure safety is a pre-requisite, for a real project this needs to be considered alongside other top level requirements - in particular the need to assure safety during construction and operation, to minimize environmental impact and to encourage public acceptance. Such concerns may lead to significant modifications of the repository appearance but, to the extent possible, emphasis should be placed on the well-established and demonstrably robust EBS components from H12. The most important of these is the buffer, which is considered in some detail in this paper.