After-accident pressurizer water level measurement system and method

The invention relates to a nuclear power technology, and specifically discloses an after-accident pressurizer water level measurement system and a method. The measurement system comprises an upper portion pressure taking joint, a lower portion pressure taking joint and a condensation vessel, wherein the condensation vessel is connected with a water level measurement differential pressure transmitter through a reference pipe, the lower portion pressure taking joint is connected with the water level measurement differential pressure transmitter and a pressure measurement transmitter, and a temperature transmitter is connected with a surface mounted platinum resistor thermometer through a temperature measurement electric cable. The method comprises: determining the height difference between the upper portion pressure taking joint and the lower portion pressure taking joint and the height difference between the horizontal plane of the condensation vessel and the lower portion pressure taking joint at the cold sta