Study on seismic qualification and seismic margin assessment of the electromotor of nuclear power plant

According to the nuclear safety regulations, the cooling electromotor of nuclear power plant is nuclear safety 2E, which must be safety to withstand the several OBE and SSE earthquake excitation. In this paper, a class 1E cooling electromotor was studied by using the white noise scanning method and several artificial excitation waves though a shaking table tests. In the test, the dynamic characteristics of the motor are obtained, and the running condition of the motor is monitored. The results show that the class 1E motor was still in good condition after earthquake shock. The seismic margin of the equipment is quantified by the high confidence low probability failure (HCLPF). The conservative conclusion failure margin (CDFM) analysis method in EPRI NP-6041-SL report is easy to implement, and by it the the response spectrum clipping factor, inhibiting factor and other main parameters were selection and calculating the seismic margin factor, to get the seismic margin of the motor. (authors)