エボナイトを用いた臨界事故時における中性子被ばく線量の評価

抄録

The authors studied the feasibility of utilizing ebonite as a personal neutron dosemeter in criticality accidents. A disc-shaped ebonite, a hard rubber containing 30wt% sulfur, can be used as a highly effective criticality neutron dosemeter because of a simplicity of measurements of beta activity arising from ³²S(n, p)³²P reactions. The counting efficiency of beta particles with an end-window GM counter for an ebonite disc in 50mm diameter and 3mm thick was determined by ²⁵²Cf neutron irradiation. The neutron spectrum dependency of ³²P activity per neutron dose was computed using Monte-Carlo calculations of various neutron spectra that could be encountered in criticality accidents, and the results were tabulated as a set of spectrum correction factors. Performance tests using the SILENE reactor indicated that neutron doses could be evaluated within ±15% with the application of suitable correction factors.