Emergency preparedness research

Research on technical standards on equipment for nuclear emergency preparedness and responses

  In a nuclear emergency, it is expected that the screening tests will be conducted on a large number of vehicles and residents. The NRA’s manual shows that workers should use a Geiger-Mueller (GM) survey meter and so on. However, in order to conduct the screening tests more efficiently, it is expected that vehicle monitors will be utilized.
 In this study, we conducted a performance test of vehicle monitors owned by some local governments to simulate the screening test*.

  Sealed radiation sources were substituted for the contamination of Operational Intervention Level 4 (OIL4), the evaluation criteria to conduct simple decontamination in the contamination inspection. The radiation source was attached practically to a tire and around wipers of a vehicle, and the counting rate of γ-rays from the radiation sources was measured using the “Gamma Pole”, the portable radiation portal monitor for vehicles manufactured by the Chiyoda Technol Corporation.
  As a result, it was estimated that in the case of contamination deposited on a tire, when the vehicle passes through the portal monitor at 10km/h or less, it would be detected with a probability of 99 % or more. Similarly, it was estimated that in case of the contamination deposited on around wipers, it would be detected with a probability of 84 % or more at 5km/h or less. Consequently, it was shown that it was difficult to evaluate the both contamination on the tire and around wipers at same time, because of the contamination around the wipers was more difficult to detect than one on the tire.
  We will continue to research measurement and operation methods using the Gamma Pole, such as a method for simultaneous measurement and evaluation of both the two contamination, and then develop an effective utilization of radiation portal monitors in contamination inspection of vehicles in nuclear emergency.