RESUMO
In the criticality accident which occurred on 30 September 1999 at a uranium conversion facility in Tokai-mura, Japan, three workers were severely exposed to neutron and gamma-ray irradiation. Preliminary estimations of doses from blood properties and 24Na concentration in blood were 16-20, 6-10 and 1-4 gamma-ray gray-equivalent (gammaGyEq) respectively for the three workers. For apparent dose estimation, neutron-induced radionuclides in biological materials such as blood, hair and urine were measured. Accordingly, we detected 32p in urine samples. The concentration ratios of 32P in the urine for the three workers showed a similar tendency to those of 24Na in blood. This result indicated that the radioactivity of 32P in urine could be used to estimate the neutron exposure level.
