Basic recognition on safety of nuclear electric power generation

The safety of nuclear electric power generation is not to inflict radiation damage on public. Natural radiation is about 1 mSv every year. As far as the core melting on large scale does not occur, there is not the possibility of exerting serious radiation effect to public. The way of thinking on ensuring the safety is defense in depth. The first protection is the prevention of abnormality, the second protection is the prevention of accidents, and the third protection is the relaxation of effect. As design base accidents, the loss of coolant accident due to the breakdown of inlet pipings of reactors and the breaking of fine tubes in steam generators are included. The suitability of location is evaluated. As the large scale accidents of nuclear power stations in the past, Chernobyl accident and Three Mile Island accident are explained. The features of the countermeasures to the accident in Mihama No. 2 plant are described. The countermeasures to severe accidents, namely accident management and general preventive maintenance are explained. The background of the nonconfidence feeling to nuclear electric power generation and the importance of opening information to public are shown. (K.I.)