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摘要
高保真、高分辨率模拟让堆芯挖掘裕量成为可能。高功率密度压水堆在传统压水堆基础上提高堆芯功率密度，堆芯内可能出现泡状流甚至弹状流。功率分布、热工参数分布的不均匀性增加，给堆芯寿期设计带来挑战。本文基于RMC、Fluent开发了一套核-热-燃耗耦合工具，对功率映射方法进行改进，最终用于不同功率水平下组件的多场耦合特性分析。结果表明本文提出的功率映射算法能兼容板、帮的计算需求，具有较好的网格兼容性和几何兼容性。核-热-燃耗耦合程序通过单棒的验证，得到235U、241Pu的相对偏差小于1%。Fluent 两相流模型也通过Martin实验的验证。从不同功率水平组件的耦合结果来看，keff、功率峰因子、235U等重要核素浓度、燃料温度、冷却剂温度等参数变化趋势一致，但两相流的引入导致功率峰因子显著增大、寿期燃料最高温度变化幅度增大，同时会导致计算时间增加约1.7倍。
Abstract
High-fidelity, high-resolution simulation enables nuclear reactor margin exploration. High-Power-Density Pressurized Water Reactors (PWRs) increase power density compared to conventional PWRs, potentially leading to bubbly or even slug flow in the core. The increased non-uniformity of power and thermal-hydraulic parameter distributions poses challenges to core lifetime design. In this paper, a neutronics-thermal-hydraulic-burnup coupling tool is developed based on RMC and Fluent, with an improved power mapping method, and is subsequently applied to the multi-field coupling analysis of fuel assemblies under various power levels. Results show that the proposed power mapping algorithm can accommodate both rod-type and plate-type computational requirements, exhibiting good mesh and geometric compatibility. The coupled neutronics/thermal-hydraulic/burnup code is validated against a single-pin cell, yielding relative deviations for ²³⁵U and ²⁴¹Pu density of less than 1%. The Fluent two-phase flow model is also validated against the Martin experiment. From the coupling results for assemblies at different power levels, the trends of key parameters such as keff, power peaking factor, concentrations of important nuclides (e.g., ²³⁵U), fuel temperature, and coolant temperature are consistent. However, the introduction of two-phase flow leads to a significant increase in the power peaking factor and a larger variation in the maximum fuel temperature over the fuel lifetime, while also increasing the computational time by approximately 1.7 times.
| 关键词 | 蒙卡；CFD；高参数堆；核-热-燃耗耦合 |
|---|---|
| Keywords | Monte Carlo; CFD; High power density PWR; neutronics/thermal-hydraulics/burnup coupling |
