Study on the Operation Characteristics of the Primary Main Circulating Pump of Sodium-cooled Fast Reactor under the Switching Condition of Off-site Main and Auxiliary Power Supplies

In order to avoid reactor protection shutdown or motor auxiliary winding startup due to the operation of primary main circulating pump (hereinafter referred to as main pump) during the off-site main and auxiliary power supplies switching, the idling characteristics and speed control of main pump are analyzed, the fast speed tracking and frequency search speed tracking modes of the main pump under fast and slow switching conditions are studied respectively, and the prediction model of the minimum speed of the main pump under different modes is given. It is analyzed that the minimum speed of main pump is 708.3 r/min under fast switching condition (power off for 1.5 s) and 341.2 r/min under slow switching condition (power off for 10 s). On the main pump water bench, 1.5 s and 10 s power off tests are used to simulate the fast switching and slow switching conditions of the off-site main and auxiliary power supplies. The test results show that the minimum speed of main pump is 689 r/min under fast switching condition; The minimum speed of main pump under slow switching condition is 346.7 r/min. The predicted minimum speed is in good agreement with the test value, and the deviation is less than 3%.The test verifies the operation characteristics of the main pump under the switching condition of the main and auxiliary power supplies, which can realize that the fast switching does not lead to the reactor protection shutdown and the slow switching does not lead to the startup of the auxiliary winding, which is of guiding significance for the safe operation of the reactor.