Modifications and improvements at LOVIISA nuclear power plant

Modifications are described made on the reactors at the Loviisa nuclear power plant in Finland as against the original Soviet design. The changes in operating regime concern the rate of power changes during reactor start-up and shutdown, the temperature difference between the pressurizer and the primary circuit, as well as the operation of the main circulating pumpe during transients. A brief description is presented of the repairs made so far, namely of the steam generators, the main closing valves and the high-pressure superheaters. (Z.M.)