There has been increasing demand for uncertainty quantification (UQ) in the nuclear engineering community. Thus far, most uncertainty analyses have focused on light water reactor (LWR). As an innovative reactor, the pebble-bed high-temperature gas-cooled reactor (PB-HTGR) features a continuous-fuel-cycling operation strategy and a movable core, which means the uncertainty analysis methods used for LWRs cannot be directly applied to the PB-HTGR. In this work, we summarize recent progress in the uncertainty analysis of the PB-HTGR at the Institute of Nuclear and New Energy Technology, Tsinghua University. We propose a framework for uncertainty analysis based on the well-developed, practical design of the PB-HTGR program system. In this framework, the uncertainty sources are divided into different components and steps, and the maximum fuel temperature in a depressurized loss of forced cooling accident is chosen as the final uncertainty output parameter. However, not all the issues are resolved as this system involves a complex combination of many physical and thermal factors.

To date, within this framework, several milestones have been achieved in the PB-HTR uncertainty analysis. (1) We have developed the uncertainty analysis tool VSOP-UAM (very superior old program–uncertainty analysis in modeling), which uses a statistical sampling method. Using VSOP-UAM, we have achieved the uncertainty analysis of the equilibrium state, which is the typical state of the PB-HTGR, for the first time. (2) Using the VSOP-UAM analysis tool, we have determined the uncertainty propagation of the nuclear cross-section data, fission product yields, and key structural parameters. (3) To determine the UQ of the fission product yields, we developed an advanced sampling method that prevents the sampling of non-physical negative samples. (4) To facilitate a benchmark definition and UQ for the PB-HTGR, studies have also been conducted under the auspices of the Coordinated Research Project on High-Temperature Gas-Cooled Reactor Uncertainty Analysis in Modeling, launched by the International Atomic Energy Agency.

核工程界对不确定性量化 (UQ) 的需求不断增加。迄今为止，大多数不确定性分析都集中在轻水反应堆 (LWR) 上。作为一种创新型反应堆，球床高温气冷堆（PB-HTGR）具有燃料连续循环运行策略和可移动堆芯，这意味着用于轻水堆的不确定性分析方法不能直接应用于PB-HTGR。在这项工作中，我们总结了清华大学核与新能源技术研究所在PB-HTGR不确定性分析方面的最新进展。我们提出了一个基于 PB-HTGR 程序系统完善的实用设计的不确定性分析框架。在这个框架中，不确定性来源分为不同的组成部分和步骤，并选择在强制冷却失压事故中的最高燃料温度作为最终不确定性输出参数。然而，并非所有问题都得到解决，因为该系统涉及许多物理和热因素的复杂组合。

迄今为止，在这个框架内，PB-HTR 不确定性分析已经取得了几个里程碑。(1) 我们开发了不确定性分析工具 VSOP-UAM（建模中非常优秀的旧程序-不确定性分析），它使用统计抽样方法。使用VSOP-UAM，我们首次实现了PB-HTGR典型状态的平衡状态的不确定性分析。(2) 使用VSOP-UAM分析工具，我们确定了核截面数据、裂变产物产量和关键结构参数的不确定性传播。(3) 为了确定裂变产物产量的 UQ，我们开发了一种先进的采样方法，可以防止对非物理负样本进行采样。(4) 为便于 PB-HTGR 的基准定义和 UQ，