Abstract
In case of a nuclear facility accident, inhabitants living around a nuclear facility generally evacuate the area to prevent radiation exposure. However, people who are unable to immediately move from such areas are supposed to evacuate to local shelter facilities. Therefore, such facilities need to have sufficient radiation protection capabilities to shield occupants from radiation via strong construction and positive pressure ventilation equipment with filters to remove radioactive material to decrease internal exposure. In Japan, local shelter facilities are mostly built using steel and reinforced concrete structure, and have different characteristics, e.g., floor areas, window areas, airtightness, and positive ventilation performances. To prepare the appropriate facilities for use as shelters, an evaluation method for the radiation protection capability of each facility is necessary. In our study, we focused on air ventilation and developed an evaluation method for the radiation protection capability against internal exposure to radiation via inhalation in facilities with positive pressure ventilation equipment. Then, we evaluated the radiation protection capabilities of facilities with different characteristics under various climate conditions. To simulate the inflow of radioactive materials, we constructed a compartment model and performed a computational fluid dynamics analysis. Our evaluation results clear relationships between the outdoor wind velocity and the required differential pressure to maintain positive pressure and between the internal exposure dose and the airtightness.
