Building materials, such as brick and concrete, are known indoor radon (²²²Rn) and thoron (²²⁰Rn) sources. Most radon and thoron exhalation studies are based on the laboratory testing of pieces and blocks of such materials. To discuss if laboratory findings can be applied to a real-world environment, we conducted intensive in situ exhalation tests on two solid concrete interior walls of an apartment in Japan for over a year. Exhalation rates of radon (J_Rn) and thoron (J_Tn) were measured using an accumulation chamber and dedicated monitors, alongside monitoring indoor air temperature (T) and absolute humidity (AH_in). There were weak correlations between J_Rn or J_Tn and T or AH_in at one tested wall, and moderate correlations of J_Rn and strong correlations of J_Tn with T or AH_in at the other wall, meaning more or less seasonal variations. The findings aligned with previous laboratory experiments on J_Rn but lacked corresponding data for J_Tn. Additionally, a moderate or strong correlation between J_Rn and J_Tn was observed for both tested walls. Comparison with theoretical calculations revealed a new issue regarding the impact of each process of emanation and migration within concrete pores on radon and thoron exhalation. Overall, this study provides insight into parameterizing radon and thoron source inputs in modeling the spatiotemporal dynamics of indoor radon and thoron.

Inevitably generated. In particular, the long-term safe disposal of high-level radioactive waste (HLW), which contains radionuclides with high radioactivity levels and long half-lives, has long been a concern in countries that use nuclear power. These countries plan to dispose of HLW deep underground (i.e., geological disposal) so that it would not affect human health and the environment in the distant future. However, they face difficulties in reaching a social consensus on the selection of burial disposal sites and the method of ensuring the safety of disposal facilities. It would take a long time before important to consider the issue from humanity and social science perspectives, in addition to explanations from a science and engineering perspective as has been done so far and have exchanged information and opinions at the "Special Study Group on Considerations from a Humanities and Social Science Perspective on the Management and Disposal of Radioactive Waste," which was established by the Japan Health Physics Society in 2022. This paper reports on the knowledge and ideas shared and agreed upon through these discussions over approximately two years.