Bioassay for Neutron-Dose Estimations of Three Patients in the JCO Criticality Accident in Tokai-mura by Measuring β-ray Emitters

Abstract

The measurement of β-emitters in biological samples (hair, urine and bone) from three patients in the JCO criticality accident was performed to assess the neutron dose to individuals. The result of the measurements of ³²P in hair and urine collected immediately after the accident showed that sufficient ³²P activities had been induced in the hair by fast neutrons and in the urine by thermal neutrons to know the severity of the exposure to the individuals and to the position. From the measurement of ³²P and ⁴⁵Ca in bone from various anatomical parts of two patients who died 82 and 210 days after the accident, it was suggested that the distribution of the induced β-emitters activities could prove the position and posture of the patients at the moment of exposure.