Illustration of barrier performance using a relevant yardstick to compare radionuclide fluxes from the HLW repository in a generic PA model

Miyahara, Kaname  ; Kato, Tomoko 

The effectiveness of barrier performance of a disposal system can be estimated by fluxes of disposal facility-derived radionuclides as a complementary safety indicator, if appropriate yardsticks for comparison are used. Natural radionuclide fluxes due to geological processes such as erosion and river flow have potential for use as yardsticks. However, since those geological processes are variable in different locations and time, it is possible to define a range of environmental fluxes which provide alternative yardsticks. H12 conceptual model is chosen for estimating radionuclide fluxes. At discharge point from major water-conducting fault to aquifer, these fluxes are compared with fluxes of natural radionuclides in corresponding groundwater flow by conservatively assuming that a groundwater flow rate at the depth of repository is prevail in shallower depth up to the aquifer. This paper discusses the relevance of this yardstick to illustrate the effectiveness of barrier performance.