SAFETY DESIGN PHILOSOPHY OF MITSUBISHI PWRS

The basic safety design philosophy of Mitsubishi pressurized water rea ctors (PWRs) is discussed and compared with the British PWR. PWR plant s are designed in accordance with the Japanese regulatory guidelines w hich are similar to American and International Atomic Energy Agency (I AEA) safety criteria and are based on defence-in-depth principles. The high reliability of nuclear power plants is especially emphasized in Mitsubishi PWRs, and this has been demonstrated by the good operating experience of PWR plants in Japan. The safety system designs of six ke y items, which were discussed in the recent review of overseas designs by British utilities, are addressed to show the difference in the des ign philosophy between the United Kingdom and Japan.