Japan Atomic Energy Agency has been conducting in situ stress measurements using overcoring method, within the context of establishing a firm scientific basis for safe geological disposal of high-level radioactive waste. Core disking has been observed during rock stress measurements performed using the Compact Conical-ended Borehole Overcoring Technique in borehole with inflow excavated at 200m depth at the Mizunami Underground Research Laboratory. In this report, applicability of measurement tool against inflow and failure initiation of core disking is discussed.
