Study on Reactor Vessel Water Level Measurement Method for Emergency Decision-Making of Nuclear Power Plant

Abstract After a nuclear accident, the nuclear power plant will monitor and analyze the unit status, environmental characteristics and accident process, determine the emergency state classification under the nuclear accident conditions, and respond to the emergency state hierarchically, to reduce the impact of the accident and ensure the safety of personnel. For determining emergency state classification of nuclear power plant cold shutdown and refueling shutdown operation mode, reactor vessel water level is an important basis for judging. The Three Mile Island nuclear accident made the industry realize the necessity of monitoring the primary water load, especially the water level in the Reactor vessel. Reactor vessel water level provides an essential basis for monitoring the core cooling state after an accident, to ensure that the core cooling state can be diagnosed correctly in time, accurately and conveniently, thus providing a criterion for determining the emergency state level, and then selecting the appropriate accident operation strategy. Based on the demand analysis of emergency state classification based on reactor vessel water level, combined with the current situation of reactor vessel measurement in Reactor vessel and the setting of peripheral dose rate monitoring channels, this paper supplements the water level measurement method under potential water loss conditions, realizes the full-range measurement of Validity water level in Reactor vessel, evaluates Validity water level Validity in Validity, and then efficiently determines the emergency state classification, providing Validity basis for emergency response.