Selection and Experimental Research of the Passive Start-Up Neutron Detector in Nuclear Power Plant

In order to monitor the reactor core during the first cycle charging, shutdown and start-up of nuclear power plants, domestic and foreign nuclear power plants generally introduce two primary neutron source components in the core, but the primary neutron sources are imported from the United States, which has the problem of import limitations. In order to solve this problem, it is studied to cancel the primary neutron source component in the first cycle and use the neutrons produced by the spontaneous fission of the fuel assembly as the starting neutron source. The neutron intensity produced by spontaneous fission of fuel assembly is much lower than that of primary neutron source. In view of the above situation, it is necessary to use a higher sensitivity detector to monitor the neutron fluence rate outside the reactor. Based on the analysis of the basic principles of various high-sensitivity detectors, this paper gives suggestions on the selection of high-sensitivity neutron detectors, and verifies their performance by experiments. The experiment results show that even when the γ dose rate is greater than 0.1 Gy/h, the ³He proportional counter tube can be set with an appropriate discriminating voltage, and can effectively discriminate γ noise. The maximum γ dose rate verified by the experiment is 1.0 Gy/h.