Research of the disturbances to reactor vessel water level measurement due to physical phenomena in CPR1000 nuclear power plants

The reactor vessel water level (L VSL) measurement in CPR1000 nuclear power plants is carried out by the core cooling and monitoring system (CCMS). The L VSL is obtained by measuring the pressure difference between the upper and lower extremities of the reactor vessel which may be disturbed by varied post-accident physical phenomena. These phenomena, which may disturb the measuring sensors, or upset the dynamic or static head loss in the reactor vessel, and the phenomena specific to the vessel dome, are reviewed in this paper. It can be observed that the L VSL measurement, although affected by a certain number of uncertainties, together with the subcooling margin (ΔTSAT), provides a sufficient understanding of the core cooling state and can be benefit to the post-accidental state oriented procedure (SOP) operation.