Development of safety assessment method for human intrusion scenario in Japan, 1; Drilling scenario database for safety assessment of geological disposal (Contract research)

Nagasawa, Hirokazu; Takeda, Seiji ; Kimura, Hideo; Sasaki, Toshihisa*

In deep geological disposal or intermediate depth disposal, human intrusion, i.e. accidental excavation or drilling into the disposal site, may make a direct or indirect effect on the disposal system. Assessment of the human intrusion would need the examination of institutional control to reduce the probability of the intrusion occurring, the estimation of its probability, and the development of method to estimate its associated exposure of persons, as well as some foreign countries. Assuming that drilling action into the disposal site especially leads to the human proximity to the radioactive waste or the damage to the barrier system (drilling scenario), we have collected both the data on borehole drilling implemented in Japan and information on actual situation of drilling activities. We have developed an assembly of the information mentioned above as database, including the model parameters used in the code to assess radiation dose for drilling scenario.