Online Core Monitoring Method in WH type PWR

Measurement of 3D power distribution in Westing-house type PWRs is performed every 31 EFPD to verify the validity of the nuclear design. Nuclear safety parameters are confirmed through the measured 3D power distribution per the Technical Specifications. This surveillance warrants the next one month operation with only axial flux deviation monitoring using ex-core detector. The aggressive core operation, for example long cycle length and power up-rate, makes the reduction of safety margin. So, online core monitoring is necessary for safe operation and advanced nuclear fuel vendors have their unique system. In the case of WH type PWRs, the plants have thermocouples and ex-core detectors which are online monitored and the signals are stored at plant main server and web server. Real time 3D core power distribution can be generated using thermocouple and ex-core detector signal and the 3D power distribution is calibrated by monthly flux measurement. Therefore nodal calibration method using monthly measured power distribution, radial power shape calibration method with thermocouple signal and axial power shape calibration method with ex-core detector are studied and the online core monitoring program is developed on this paper