Investigation in Verification of Limiting Power Shape in HPR1000

The core power distribution which is composed of radial power distribution and axial power distribution is of greater importance for departure from nucleate boiling (DNB) analysis. The power shapes differ from one another during normal operation and accident condition. In order to simplify analysis of each accident condition, the limiting power shape is used to bound the core power distribution according to the change of core power distribution due to accident condition and the characteristics of protection system of nuclear power plant. Based on the protection system of HPR1000 and core power capability analysis methodology, the investigation in verification of limiting power shape in HPR1000 was introduced. The results show that the design power shape bounds the core power distributions in category I and the reference power shape bounds the core power distributions in accident conditions protected by the overtemperature ΔT protection system. The results not only assist engineers to understand the verification method of limiting power shape, but also are helpful for properly use of limiting power shape in accident analysis.