It is examined how and to what extent cost-benefit analysis can be used in the decision-making concerning the regulation of foodstuffs contaminated with radioactive substances released from the accident of the Fukushima Daiichi Nuclear Power Plants. Cost per life-year saved is calculated for the ban of the distribution of the vegetables harvested in March and April 2012 just after the accident. It is estimated at 20 million yen. Cost per life-year saved is also estimated for the stop of the distribution of the rice harvested in autumn in some parts of the three municipalities at 1.0 billion yen. The former is smaller and the latter is larger than the values for the cost per life-year saved for the past regulation of toxic chemicals. The former is as large as the value of a life-year based on willingness to pay for risk-reduction, but the latter is much larger than that. Limit values for foodstuffs are proposed which would make the cost of regulation never exceed its benefit. The limitations of cost-benefit analysis are discussed, and what is necessary for the future regulation is suggested.
We developed a Ge semiconductor detector system that allows real-time mapping of radionuclides using a vehicle. We used this system to conduct a background survey in the Chugoku Region of Japan. 214Bi (U-series) concentration was high in the east and west of Hiroshima Prefecture; 208Tl (Th-series) concentration was high in Oki-island in Shimane Prefecture and in the western part of Hiroshima Prefecture, and 40K was high in the entire area of Hiroshima Prefecture, while the concentrations of all types of radionuclides were low in the plains in the eastern part of Shimane Prefecture. The artificial radionuclide 137Cs was detected in Tottori, Shimane and Yamaguchi Prefectures as well as in the Chugoku Mountains. The results of the survey did not indicate that Shimane Prefecture had been affected by the accident at the Fukushima Daiichi Nuclear Power Plant.
It is essential to wear an air-purifying respirator in the radiation works in a contaminated atmosphere. A breath-responsive-powered air-purifying respirator (BR-PAPR) has been recently developed. However, no research has yet been conducted to determine the protection factor (PF) of the BR-PAPR in actual workplaces. In this study, the PFs of the BR-PAPR were measured by a man-test apparatus and compared with those of a non-powered full face mask. The PFs were measured under three different situations; normal wearing condition, clogging the filter and leaving a gap between the face and the mask. Under these situations, it was found that the PFs of the BR-PAPR are higher than those of the non-powered full face mask. PFs greater than 4,000 were obtained for 95% of the subjects who wear the BR-PAPR, and PFs over 6,667, the upper limit of the man-test apparatus, were obtained for 49% of them. The questionnaire survey was conducted for workers. The results showed that the workers feel a reduced burden when they wear the BR-PAPR. The results of this study showed high protection performance and operation efficiency of the BR-PAPR.
A computer simulation program has been developed to train the practitioners examining the surface contamination of objects to be carried out from the controlled area. The efficiency of the examination depends significantly on the proficiency in radiation measurement and proper perception of contamination. It has been demonstrated through the usage of the program that it helps practitioners very much suggest their weakness and promote their skill in examination. The program runs on the commonly used personal computers and users can easily experience the virtual examination by sweeping and cricking the mouse. The program is useful to radiation protection practitioners not only beginners but also experts.