The large advanced pressurized water reactor core undercooling monitoring system is a subsystem of the large advanced pressurized water reactor nuclear safety system, which measures the liquid level of the reactor pressure vessel and is used to monitor the occurrence of insufficient core cooling.
This system adopts the principle of differential pressure method to measure the static pressure difference at the top and bottom of the reactor pressure vessel, as well as the dynamic pressure difference during the operation of the cooling pump. Two differential pressure signals are collected by the data processing system and combined with temperature characteristic data. After pressure and temperature compensation, the liquid level inside the reactor pressure vessel is calculated and the occurrence of monitoring cavities or bubbles is monitored. Among them, static pressure difference is an important safety parameter after a reactor loss of coolant accident. The system is generally referred to as a reactor pressure vessel liquid level measurement system. In the nuclear power plants designed and constructed in our country, the measuring instruments of this system are all selected from foreign products.