Efficiency of Application of Variable Frequency Drives of Main Circulation Pumps in NPPs with WWER

Decompaction of electric load graphs under the condition of insufficiency of maneuverable capacities (especially in the power systems of the European part of the Russian Federation, with the increasing share of nuclear generation) determines the need to involve nuclear power units in maneuvering modes according to the dispatch schedule. In the long term, nuclear power plants should be ready for long-term operation with a certain (optimal) power reserve in the regime of readiness for a rapid increase of the load for emergency control of the frequency in the event of its fall and a rapid decrease of the load with an overabundance of generation in an unacceptable frequency increase situation. In the most severe situations with a long drop in frequency, the acceleration performance of a nuclear power plant with a WWER can be increased by introducing an additional regulation parameter - the coolant flow rate when installing the variable-frequency drive of the main circulating pump, which has long existed with reactors with fast neutrons, and also with some BWRs in USA. The article shows the additional advantages of the installation of variable frequency drive of the main circulation pump. Firstly, this makes it possible to amplify the impulses of the load change, much more quickly realizing them through a change in the coolant flow rate. Secondly, by increasing the number of revolutions of the main circulation pump, it is possible to increase the permissible value of the heat exchange crisis (DNBR), which will expand (in conjunction with other modernizations) the range of power increase.