反应堆堆芯先进中子学模拟软件SCAP-N研发

堆芯中子学计算是反应堆设计分析的基础，为提高堆芯中子学计算的模拟分辨率与计算精度，开发了反应堆堆芯先进中子学模拟软件（SCAP-N）。该程序首先根据轴向特征对堆芯进行分层，并逐层进行二维堆芯非均匀输运计算，再采用超级均匀化方法（SPH）获得栅元等效均匀化截面，最后进行三维堆芯逐棒（pin-by-pin）输运计算，获得堆芯有效增殖因子与精细棒功率分布。为提高程序计算效率，采用分布式/共享式（MPI/OPENMP）混合并行方式对程序进行了并行化开发。利用虚拟反应堆（VERA）系列基准例题及美国先进非能动压水堆（AP1000）启动物理试验实测数据对程序进行了测试验证。结果表明，相比于商用核设计程序系统，SCAP-N程序采用的逐棒输运技术能够提高堆芯中子学的计算精度。与同类型高精度中子学程序相比，SCAP-N具有更高的计算效率，可进一步提高核电厂的经济性及运行灵活性。 

Development of Advanced Neutronics Code SCAP-N for Reactor Core High Fidelity Simulation

Reactor core neutronics calculation is important for the reactor design and analysis. In order to improve the resolution and accuracy of the reactor core neutron transport simulation, the advanced neutronics code SCAP-N was developed. In this code, firstly, the core was divided into layers according to the axial characteristics. Secondly, the two dimensional neutron transport calculation was carried out for each layer. Then the homogenized cross sections of all cells were obtained using the super homogenization method. Finally, the three dimensional pin-by-pin transport calculation was carried out to obtain the core effective multiplication factor and the pin power distribution. In order to improve the calculation efficiency, the MPI/OPENMP hybrid parallel method was adopted. The VERA benchmark problems and the AP1000 reactor start-up physical testing problem were used to verify the code. Numerical tests show that the pin-by-pin transport technology adopted by SCAP-N can improve the accuracy of core neutronics calculation compared with the commercial nuclear design system, and SCAP-N has higher computational efficiency compared with other high fidelity neutronics codes, which can further improve the economy and operation flexibility of nuclear power plants..