Abstract Over the years, significant validation work for the neutronics code MPACT has been performed against zero-power critical benchmarks and measured data from operating nuclear power plants. Among all of these efforts, however, validation of the pin-resolved capability in MPACT has been limited by the public availability of experimental data and to a lesser degree availability of measurement techniques and facilities that provide such detailed data. Recently, new measurement results to experimentally determine the reaction rate along the pellet radius from the IPEN/MB-01 research reactor facility (IPEN) have been published as a benchmark in the International Reactor Physics Experiment Project handbook. In this paper, we examine MPACT simulation results for several IPEN benchmark experiments with emphasis on the intrapin reaction rate measurements. The IPEN critical experiments with variations in system temperature and gadolinium loadings are modeled first with the latest MPACT cross-section library and linear source (LS) method of characteristics (MOC) capability. The MPACT results of two-dimensional (2-D) models with axial buckling are within 160 pcm from the experimental eigenvalues using the flat source MOC. Using the LS MOC, the errors are no more than 70 pcm, and the temperature trend of various cases is smaller. The MPACT three-dimensional models with LS show slightly worse comparisons than the 2-D models, which may be due to the isotropic transverse leakage and homogenized cross-section approximations of the 2-D/one-dimensional solver. For the reaction rate validation, MPACT produces intrapin reaction rate results within 2σ of the experiment and shows excellent agreement with the Monte Carlo solution. The observed discrepancies between the simulated results and experiment for the fission rate measurements are discussed. The kinetics parameters measured in another IPEN experiment are also compared with MPACT simulations using different kinetics data sources. According to the validation results, JENDL-4.0 and Santamarina et al.’s data are recommended for MPACT transient calculations.

中文翻译：

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MPACT 中引脚分辨反应速率、动力学参数和线性源 MOC 的验证

摘要 多年来，针对零功率临界基准和运行核电厂的测量数据对中子学代码 MPACT 进行了重要的验证工作。然而，在所有这些努力中，MPACT 中引脚解析能力的验证受到实验数据的公开可用性以及提供此类详细数据的测量技术和设施的较小程度的可用性的限制。最近，国际反应堆物理实验项目手册中公布了新的测量结果，用于通过实验确定 IPEN/MB-01 研究堆设施 (IPEN) 沿芯块半径的反应速率，作为基准。在本文中，我们检查了几个 IPEN 基准实验的 MPACT 模拟结果，重点是内销反应速率的测量。系统温度和钆负载变化的 IPEN 关键实验首先使用最新的 MPACT 横截面库和线性源 (LS) 特性方法 (MOC) 功能建模。具有轴向屈曲的二维 (2-D) 模型的 MPACT 结果与使用平面源 MOC 的实验特征值相差在 160 pcm 以内。使用LS MOC，误差不超过70 pcm，各种情况下的温度趋势更小。具有 LS 的 MPACT 三维模型显示出比二维模型稍差的比较，这可能是由于二维/一维求解器的各向同性横向泄漏和均匀横截面近似。对于反应速率验证，MPACT 在实验的 2σ 范围内产生内销反应速率结果，并与蒙特卡罗解决方案显示出极好的一致性。讨论了模拟结果与裂变速率测量实验之间观察到的差异。在另一个 IPEN 实验中测量的动力学参数也与使用不同动力学数据源的 MPACT 模拟进行了比较。根据验证结果，推荐JENDL-4.0和Santamarina等人的数据进行MPACT瞬态计算。在另一个 IPEN 实验中测量的动力学参数也与使用不同动力学数据源的 MPACT 模拟进行了比较。根据验证结果，推荐JENDL-4.0和Santamarina等人的数据进行MPACT瞬态计算。在另一个 IPEN 实验中测量的动力学参数也与使用不同动力学数据源的 MPACT 模拟进行了比较。根据验证结果，推荐JENDL-4.0和Santamarina等人的数据进行MPACT瞬态计算。