Survey on current status of laboratory test method and experimental consideration for establishing standardized procedure of material containing bentonite; Report of Collaboration Research between JAEA and CRIEPI (Joint research)

Tanai, Kenji ; Kikuchi, Hirohito; Nakamura, Kunihiko*; Tanaka, Yukihisa*; Hironaga, Michihiko*

Bentonite-based material is used as one of the components of the LLW, TRU and HLW disposal facilities. Required characteristics of bentonite-based material are low permeability, swelling property, etc. Those are evaluated in many cases by laboratory test results. However the uncertainty exists in the evaluation of those characteristics in construction. Because even if the index of the dry density etc is the same, laboratory test results have variability. In addition, the uncertainty in construction has the possibility to increase the uncertainty of long-term evaluation of characteristics. On the other hand, several of laboratory test methods of bentonite are not standardized. So, this is a possibility that is one of the uncertain causes of the evaluation of characteristics of the bentonite. Therefore, it is hoped that the laboratory tests of bentonite are standardized. Therefore, this study analysis the uncertainty on the physical properties by laboratory tests and put together the problem and ponts of concern in the tests.