压水堆燃料棒污垢沉积层内的多物理场耦合  

Multi-physics Coupling within Chalk River Unidentified Deposit on Pressurized Water Reactor Fuel Rod

作　　者：高全燚 丛腾龙 田洪康 刘茂龙 顾汉洋[1] GAO Quanyi;CONG Tenglong;TIAN Hongkang;LIU Maolong;GU Hanyang(School of Nuclear Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Institute of Modern Physics,Fudan University,Shanghai 200433,China)

机构地区：[1]上海交通大学核科学与工程学院,上海200240 [2]复旦大学现代物理研究所,上海200433

出　　处：《原子能科学技术》2025年第2期372-382,共11页Atomic Energy Science and Technology

基　　金：国家自然科学基金(12375171,12135008);上海市自然科学基金(23ZR1428300)。

摘　　要：燃料棒表面污垢沉积(CRUD)层的形成一直是压水堆运行中的难题。硼物质在CRUD内的浓缩导致冷却剂饱和温度升高,进而影响热质传输过程,同时增加了堆芯功率偏移(CIPS)的风险。为深入理解CRUD内的传热传质特性,基于灯芯沸腾结构开发了一个二维污垢化学模型。该模型包括沸腾传热、毛细作用流动、组分输运、化学反应和辐照分解等多物理过程,能够合理预测CRUD内的温度、速度和浓度分布。研究结果表明:考虑硼酸挥发过程的情况下,燃料包壳表面温度的预测值更接近WALT实验数据;饱和温度与硼浓缩量密切相关,随着可溶硼在燃料包壳表面浓缩,饱和温度达到峰值619.32 K;CRUD中硼以可溶硼、沉淀硼和吸附硼3种不同形态存在,其中可溶硼占主导,为98.5275%;CRUD底部的pH值显著增加,在一定温度下LiBO_(2)的析出量由pH值决定。本文还分析了厚度、孔隙率、烟囱密度和烟囱半径等污垢几何参数对硼浓缩量和沸腾传热过程的影响,结果可为燃料棒表面污垢多物理场耦合提供一种计算框架,为堆芯轴向功率偏移的预测提供技术支持。The formation of Chalk River unidentified deposit(CRUD)on the surfaces of fuel rods within pressurized water reactor(PWR)causes significant operational challenges.This study focuses on the characteristics of heat and mass transfer processes within CRUD,which is crucial for improving reactor safety and efficiency.The accumulation of boron in CRUD influences coolant saturation temperature,affecting thermal properties and increasing the risk of CRUD-induced power shift(CIPS),which can lead to substantial economic losses.To address these issues,a two-dimensional CRUD chemistry model(CCM)based on a wick boiling structure was developed.This model integrated multiple physical processes,including boiling heat transfer,capillary flow,mass transport,chemical reactions,and radiolytic decomposition,to accurately predict temperature,flow velocity,and concentration distributions within CRUD.The heat transfer model used wick boiling model to calculate temperature distributions within CRUD,incorporating evaporative heat transfer on the surfaces of steam chimney.The heat transfer model obtained saturation temperature from the solute transport model and provided evaporative water flux to the fluid model.Using Darcy’s law,the fluid model calculated pressure distributions and velocity profiles within CRUD,which facilitated convective mass transfer to the solute transport model.The transport model simulated the transport of species by using diffusion and convection.The sources and sinks of mass within this model were governed by the chemical reaction model and radiolysis model.Research reveals that considering volatilization of boric acid results in predictions of cladding surface temperature that is closer to those observed in WALT experiment.The saturation temperature within CRUD correlates with boron concentration,peaking at 619.32 K as soluble boron accumulates on the cladding surface.Boron in CRUD exists in three forms:soluble boron,precipitated boron and adsorbed boron,with soluble boron predominating at 98.5275%.Additionally

关 键 词：污垢沉积 硼浓缩 多物理场耦合 堆芯功率偏移 化学反应 

分 类 号：TL331[核科学技术—核技术及应用]