Abstract This paper presents the three new pin-resolved transient solvers of PROTEUS-MOC developed in a consistent way to the latest steady-state solver. A new transient fixed source problem (TFSP) solver was developed without relying on the isotropic approximation of the angular flux time derivative. A moving axial mesh scheme was also implemented to model the control rod movement accurately with coarse axial meshes. In addition, in order to reduce the computational time further, an improved quasi-static method (IQM) solver and a predictor-corrector quasi-static method (PCQM) solver were developed in a consistent way to the TFSP solver. Initial verification tests were performed using the C5G7-TD benchmark problems. The results of the direct TFSP solver agreed very well with the MPACT and NECP-X solutions within ~2.5%. Additional analyses suggested that the observed differences are mainly due to the coarse time steps used in the MAPCT and NECP-X calculations. These results indicate that the direct TFSP solver of PROTEUS-MOC was correctly implemented and the moving axial mesh scheme is working properly. Numerical tests of IQM and PCQM against the direct TFSP solver showed that the IQM and PCQM solvers can reduce the computational time about 10 to 100 times without any significant loss of accuracy by allowing larger time steps. The PCQM calculation with the quadratic interpolation of kinetics parameters (KPs) showed the best performance among the four combinations of the IQM and PCQM solvers and the linear and quadratic interpolation schemes of KPs. This study also showed that the different delayed neutron precursor models of six and eight families can cause larger power differences than the different high-fidelity transient codes and that the adjoint scalar flux weighting can cause significant errors in KPs and subsequently in power evolution. In addition, the transient analyses of a modified C5G7 benchmark problem containing a void channel similar to the hodoscope channel of the Transient Reactor Test (TREAT) facility showed that the isotropic approximation of the angular flux time derivative can cause nonnegligible errors in the time-dependent power distribution. This study also demonstrated that PROTEUS-MOC can be used for transient analyses of reactors with internal void regions.

中文翻译：

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高保真传输码 PROTEUS-MOC 的一致传输瞬态求解器

摘要 本文介绍了以与最新稳态求解器一致的方式开发的 PROTEUS-MOC 的三个新的引脚解析瞬态求解器。开发了一种新的瞬态固定源问题 (TFSP) 求解器，该求解器不依赖于角通量时间导数的各向同性近似。还实施了移动轴向网格方案，以使用粗轴向网格准确模拟控制杆的运动。此外，为了进一步减少计算时间，以与 TFSP 求解器一致的方式开发了改进的准静态方法 (IQM) 求解器和预测校正准静态方法 (PCQM) 求解器。使用 C5G7-TD 基准问题执行初始验证测试。直接 TFSP 求解器的结果与 MPACT 和 NECP-X 解法的结果非常吻合，误差在 2.5% 以内。其他分析表明，观察到的差异主要是由于 MAPCT 和 NECP-X 计算中使用的粗略时间步长。这些结果表明 PROTEUS-MOC 的直接 TFSP 求解器已正确实现，并且移动轴向网格方案工作正常。IQM 和 PCQM 与直接 TFSP 求解器的数值测试表明，IQM 和 PCQM 求解器可以通过允许更大的时间步长将计算时间减少约 10 到 100 倍，而不会显着降低精度。使用动力学参数 (KP) 二次插值的 PCQM 计算表明，在 IQM 和 PCQM 求解器的四种组合以及 KP 的线性和二次插值方案中，性能最佳。该研究还表明，与不同的高保真瞬态代码相比，六族和八族的不同延迟中子前驱模型会导致更大的功率差异，并且伴随的标量通量加权会导致 KP 和随后的功率演化出现重大误差。此外，包含类似于瞬态反应堆测试 (TREAT) 设施的 hodoscope 通道的空通道的修改后的 C5G7 基准问题的瞬态分析表明，角通量时间导数的各向同性近似会导致随时间变化的不可忽略的误差。电力调配。该研究还表明，PROTEUS-MOC 可用于具有内部空隙区域的反应堆的瞬态分析。