Summary of operating experience in Swiss nuclear power plants 1994

In 1994 the Swiss nuclear power plants produced their highest-ever combined annual output. Their contribution to total electricity generation in the country was 36%. At Muehleberg the power uprate, undertaken in 1993, was effective for the first time for an entire year. The larger capacity of the new steam generators installed in 1993 in unit 1 of the Beznau NPP allows for an electric output of 103% of nominal power. The plant efficiency of the Goesgen and Leibstadt units was increased by replacing the low pressure turbines by the new ones with a modern design. The application for a power uprate of the Leibstadt reactor is still pending. For the first time in Switzerland, one of the reactor units, Beznau 2, operated on an extended cycle of one and a half years, with no refuelling outage in 1994. In spite of the replacements of two of its three low pressure turbines, Goesgen had the shortest refuelling shutdown since the start of commercial operation. The average number of reactor scrams at the Swiss plants remained stable, at less than one scram per reactor year. Re-inspection of crack indications detected in 1990 in the core shroud of the Muehleberg reactor revealed no significant changes. A crack indication was found in one of the other welds inspected. The Swiss government issued a limited operating licence for Beznau 2 for the next ten years, i.e. until the end of 2004. The only other unit with a limited operating licence (until 2003) is Muehleberg. The remaining three reactor units, have no time limits on their operating licences, in accordance with the Atomic Law. Goesgen is the first Swiss nuclear power plant having now produced more than 100 billion kWh. As from January 1, 1995, the nominal net power of the largest Swiss reactor unit, Leibstadt, has been fixed at 1030 MW; that of the Goesgen NPP has been increased by 25 MW to 965 MW. (author) figs., tabs