Radioactive aerosols and vapors are dispersed into the work space through dismantling activities, and are then released or leaked to the atmosphere through filters and buildings, or released to the ocean through filters in the disposal system. The public exposure dose is evaluated considering various pathways, for example, the internal dose by inhalation of radionuclides in the air, the external dose from radionuclides on the ground surface, and the internal dose from the ingestion of food.