Development, Verification, and Application of a Multiphysics Coupled Deterministic Analysis Program for the Reactor Core

[Background]: Traditional core calculation programs often employ simplified models or loosely coupled methods to enhance computational efficiency. However, with the continuous improvement of computer performance and the increasing demand for higher accuracy in calculations, traditional approaches are no longer sufficient to meet the current requirements for computational performance. [Purpose]: This study aims to develop a core calculation code that employs more accurate theoretical models and a more intensive multi-physics coupling approach. [Methods]: The three-dimensional multiphysics core analysis program developed in this paper achieved coupled calculations of neutronics, thermal-hydraulics, and fuel performance through internal program coupling. To further enhance computational accuracy, the program employed more precise calculation models. Specifically, the neutronics calculations utilized the semi-analytical nodal method, the depletion calculations adopted the microscopic depletion method, and the thermal-hydraulics calculations were based on the subchannel thermal-hydraulic model. Additionally, to improve computational efficiency, the traditional two-step method of assembly-to-core was utilized. [Results]: To verify the computational performance of the program, it was validated against actual measurement data of the domestic M310 type plant. The validation results show that: the calculation deviation of the integral worth of the control rod group in the physical startup test of the core is within the range of -2.9% to 2.8%, which is far lower than the design criterion of ±10%; the calculation deviations of the core cycle length and the radial power distribution of the core are also very small, far lower than the design criteria. [Conclusions]: The validation results show that the core calculation code possesses high computational accuracy and fast computational efficiency, meeting the practical needs of engineering applications. The subcritical control rod worth measurement system and core operation support system developed based on this code further validate the computational performance and reliability of the code.