Research on Environment Monitoring of Radiation Emergency

Ito, Yoshifumi*; Endo, Nobuyuki*; Otani, Nobuo*

In a case of nuclear accident at nuclear facililties, strong radiations such as g-rays and neutrons might radiate at a bust in the initial stage. For the establishment of dose estimation system for such accidents, the experiments were done using the 200 MeV proton beam accelerated by synchrotron in the W-MAST. DC current mode neutron detection sysstem was tested for hegh dose neutron irradiation, where ther system was composed by NE213 scintillate, photomultiplier and pre-amp. The following results were obtained: (1) When one fast neutron was injected into NE213, the shape of pre-amp output signal wa Gaussian type with the full width of half maximum of -40ns. (2) Linear relation between the radiation intensity of neutron and the proton current was obtained in the detection system. The neutron more than 25 Mcps can be detected using this detection system with the DC current mode. In order to establish the method of the dose of radioactivity measuring using the electron spin resonance (ESR) technique, stable free-radicals generated in the tooth enamel by gamma-ray irradiation as basis research was measured with ESR equipment, precise signal analysis was performed, and the dose evaluation characteristic of having purpose at higher sensitivity was investigated. Moreover, the relationship between the dose of radioactivity and ESR signal intensity of free-radical species which were generated by X-ray irradiation, and damping behavior of the signal were evaluated about seven kinds of analogous inorganic compound to tooth enamel.