Monthly ⁷Be depositions were examined at four sites in Hokuriku, Japan, from 1992 to 2021. The amounts of ⁷Be depositions in Hokuriku from October to March differed locally: Depositions at Kanazawa were high (4,400 Bq/m²), a site along the foot of the mountains. ⁷Be depositions in the plain of Fukui city, along Wakasa Bay and along the coast of the Noto Peninsula (3,300, 2,800 and 2,500 Bq/m², respectively) were equivalent to those of other areas along the coast of the Sea of Japan. The local variation in ⁷Be depositions in Hokuriku is predominantly ascribed to precipitation, topographic feature and ⁷Be concentrations.

In this study, by using an online survey, we obtained responses regarding basic knowledge of radiation and anxiety associated with radiation exposure from 500 general construction workers, who are likely to be engaged in decontamination work after a nuclear disaster or radiation accident, and 200 radiological technologists, who have expertise in the biological effects and clinical applications of radiation. A chi-square test showed significant differences in the groups’ basic knowledge of radiation; the degree of anxiety about radiation exposure was significantly greater among general construction workers than among radiological technologists. In addition, a logistic regression analysis revealed a significant correlation between knowledge of “the difference between natural and artificial radiation” and “the difference between internal and external exposure” and anxiety associated with radiation exposure. Taken together, our findings suggest that appropriate radiation education may contribute to reducing anxiety associated with radiation exposure.

A concept figure of radiation protection criteria for Naturally Occurring Radioactive Materials (NORM) is proposed based on a continuous scale without explicit boundaries. The criteria map tries to visually classify various exposures to NORM by the following two axes: category and situation of exposure. Its free division concept by several zones proposed in this study shows us where the target exposure to NORM is positioned in a map for the determination of radiation protection strategy. For example, a target dose within the range of 5 to 10 mSv/y (up to 20 mSv/y) could be considered as one of occupational exposure activities if the frequency is high, even if that might be generally categorized into the existing exposure situation for the public. From an international view, as in Canada, Australia, etc., the concept of controlled area has already been applied in their NORM industries. A NORM worker in these countries is categorized as a kind of radiation worker. Related radiation protection strategies would be determined by the regulatory policy and should be based on the culture of each country. The criteria map proposed by the authors helps to make a rational communication to discuss adequate options for radiation protection on large varieties of NORM exposures.

During the glovebox dismantling activities, workers in air-fed suits would have been exposed to radioactive materials. In view of the potential exposure risk, a series of radiological control measures have been put in place. Prior to the commencement of glovebox dismantlement activities, a comprehensive radiological survey was conducted to ascertain the dose rates within the designated operational area. Based on these results, the external exposure doses to the workers were estimated throughout the course of the work. These estimates were incorporated into the work plan, wherein a management reference value for external exposure was defined. The external exposure dose to which the worker is subjected is limited by the continuous monitoring of the air dose rate in the operational area and the monitoring of the worker’s dosimeters. To prevent internal exposure for workers, the surface density of radioactive materials and the concentration of radioactive materials in the air are measured. Subsequently, respiratory and body protective equipment with an appropriate protection coefficient is selected, and a management reference value for internal exposure is defined. The inhalational hazard faced by the worker is managed by continuously monitoring measurement values that fall within the aforementioned management reference value. In this report, the radiological management activities are elucidated in detail, with concrete procedures and data from the dismantling of the liquid waste treatment gloveboxes previously performed.