中子时空动力学计算程序CORCA-K的进展

主要介绍了自主化中子时空动力学程序CORCA-K的相关研发进展。CORCA-K程序是中核集团自主研发的NESTOR软件包中的三维瞬态中子学计算软件。其核心功能是采用数值计算方法，求解三维瞬态中子扩散方程。其空间离散采用第二类边界条件节块格林函数方法，与三维稳态扩散计算程序CORCA-3D保持自洽性；时间离散采用对角线隐式龙格库塔格式，可在向后欧拉格式的基础上叠加实现，且具备时步自适应功能。以三维LMW基准问题、三维LRA基准问题和秦山核电厂3号机组第5循环为计算对象，开展了瞬态计算验证。结果表明，CORCA-K计算结果与参考程序符合较好，且在保证计算精度的条件下，具有更高的计算效率。

Progress of the CORCA-K space-time neutronics simulation code

Space-time neutronics simulation code has been widely applied to accidents analysis of pressurized water reactor power plant and technical service projects such as dynamic rod worth measurement. This paper gives a brief introduction to the progress of the self-dependent developed code CORCA-K. The CORCA-K space-time neutronics simulation code is a part of the code package NESTOR developed by CNPE. The main task of this code is to solve the three dimensional transient neutron diffusion equations with numerical methods. The spatial discretization is done by the Nodal Greens Function method with Neumann boundary condition, to keep consistency with the three dimensional static code CORCA-3D. The temporal discretization is done by the Diagonally Implicit Runge-Kutta method, which can be easily achieved on the basis of backward Euler method, and provides the code the function of automatic time step optimization. The code is verified by the three dimensional LMW/LRA benchmarks and dynamic calculation of unit 3 cycle 5 of Qinshan NPP. The verification shows that the results calculated by CORCA-K agree well with those calculated by referential codes. In addition, the code is more efficient while achieving the same accuracy level.