Radiation dose reduction in Swiss nuclear power plants

Nuclear power has been used reliably to produce electrical energy in Switzerland for about 48 years. In this time, the annual collective dose and the maximum annual individual dose have been reduced significantly. Supervised by the regulator, the licensees adopted different measures and methods to achieve this reduction. Radiation protection engineering has been improved by the deployment of shielding, barriers, cameras and electronic dosimeters. A further aspect is the steady development of staff and organization through education, preparatory work, dose optimization and mockup training. Dose reduction was part of the overall optimization and modernization of the Swiss NPPs. Dedicated attention has been put on the reduction of cobalt in the primary system, the fuel performance and the exchange of steam generators. The handling of water chemistry in the past ten years with zinc feeding or online noble chemical addition played an important role as well. (author)