Study of the screening survey using an ambient dose equivalent rate survey meter in criticality accidentsy

星 勝也; 辻村 憲雄; 吉田 忠義; 栗原 治*; Kim, E.*; 矢島 千秋*

Progress in Nuclear Science and Technology (Internet), 6, p.152 - 155, 2019/01

https://doi.org/10.15669/pnst.6.152

When a criticality accident occurs, a screening survey to triage high-dose radiation exposed persons is performed. We have established a rapid method for the screening survey by measuring the dose rate mainly from Na on the victims' body surface with a conventional NaI(Tl) scintillation survey meter. In this study, a water-filled slab phantom containing NaCl was irradiated with neutrons from a Cf neutron source. The radioactivity concentration of Na produced in the phantom was determined by means of both -ray spectrometry and simulations using the Monte Carlo N-Particle Transport Code. The ambient dose equivalent rates at the phantom's outer surface were simulated by the MCNP, and also were directly measured with a NaI(Tl) scintillation survey meter. From the experiments and calculations, we obtained the results that 1 Gy (neutron absorbed dose) corresponded to 18-76 Sv h (ambient dose equivalent rate) at the surface of the victim's body, which can be easily distinguished from normal background levels. Therefore, this method allows us to rapidly screen high-dose radiation exposed victims.