反应堆屏蔽计算是评估核电站安全性能的基础，是指导电站设计、运行的重要手段之一。JSNT程序是中物院高性能数值模拟软件中心研制的大规模并行离散纵标输运程序，具有较高的计算精度和计算效率。利用JSNT程序对某压水堆进行了建模计算，给出了中子通量密度的分布结果，并与实验测量值进行了对比。对比结果显示: 无论是采用S8计算还是S16计算，计算结果都能满足工程要求; 相比S8而言，采用S16计算可以显著提高计算精度，能够将某些测点处的相对误差降至1%以内。

Reactor shielding calculations is the foundation for assessing nuclear plant safety performance. It is also an important method to provide guidelines for constructions and operations of nuclear plant. JSNT is a massively parallel discrete ordinates transport code developed by CAEP software center for high performance numerical simulation, with high simulation precision and efficiency. In this paper, a commercial PWR has been modeled and simulated using JSNT code. Flux distributions are obtained and compared with experimental measuring results. Comparisons show that results obtained by both S8 and S16 calculations could satisfy engineering demand. Moreover, in comparison to S8 calculation, S16 could improve the calculation precision significantly and decrease relative errors of some detectors under 1%.