Reactor-follows-station loads

In the reactor-following-turbine mode of operation, the turbine generator load is set by the operator the steam generator pressure control program requests variations be made to reactor power in order to maintain a constant steam generator pressure. This control mode is termed reactor-follows-turbine or reactor-follows-station loads. 

The accident resulted from a routine safety test of some electrical control equipment at the start of a normal reactor shutdown for routine maintenance. The test was to determine the ability to continue to draw electrical power from a turbine generator during the first minute of coast-down following a station blackout. In a blackout, the reactor automatically scrams and diesel generators start to assume load (about 1 minute required). 

For 9 months during 1986, the three commissioned reactors in the Bruce B station in Canada performed extensive load following. The frequency, duration, and nature of maneuvers varied considerably typically, the frequency varied from zero to three per week, with the duration of reduced power being approximately 8 h. The station was operated with deep load following (power reduction about 40%) of up to 19 cycles, plus up to 65 comparatively shallower cycles (between 0% and 40% reduction in power) and 11 trips. If fhe trips are counted, the above maneuvers add up to a total of 95 cycles. 

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