Present state and countermeasures on radiation exposed accident accompanied with radiation applications

Nuclear power generation is, at present, carried out at total 425 power nuclear reactors in 31 nations and areas of the world, and is now planned on their construction in the other nations. On the other hand, signatories of the International Atomic Energy Agency (IAEA) are 130 nations (on the end of 1999), almost all of which carry out applications of radioisotope (RI) and radiation at various fields of medical treatments, industrial measurements, radiation applications, and so on. For such wide and versatile radiation applications, ionizing radiation formed by sealed RI sources, electron accelerators, and so on is used, and on accompanied with it, a number of radiation exposed accidents occur. Here were described on main past radiation exposed accidents, gamma ray radiation facilities, radiation sources for medical treatment and industrial radiography (non-destructive inspection), medical treatment accidents, mixing of lost sources, necessity of sealed RI source management and countermeasures on accident protection. (G.K.)