Development and Application of Integrated Accident Analysis System for PWR Based on Neutronic/Thermal-hydraulics Coupling

With the development of the rod control mode of reactor core, the increasing value of control rod makes the margin of traditional accident analysis method of rod ejection decrease. In this paper, a three-dimensional PWR integrated accident analysis system based on neutronic-thermal code is developed. The system couples the reactor core nuclear design code COCO and the sub-channel analysis code LINDEN, developed by China General Nuclear Power Group, and develops accident nuclear transient and thermal transient simulation functions based on an advanced accident analysis method. Through an integrated coupling modeling with the new rod ejection accident analysis method, the system can be used for transient process simulation in rod ejection accidents, Departure from Nucleate Boiling (DNB) consequence assessment with pin-by-pin model, and fuel integrity analysis. By comparing with the traditional rod ejection analysis method in large PWRs, the rod ejection analysis results based on the integrated accident analysis system can release the safety margin, ensure the safety of reactor core and subsequently be used for rod ejection accident analysis of rod control reactor.