铅冷快堆燃料棒包壳管表面多功能微纳结构仿生优化设计

The cladding tube of fuel rod in lead-based cooled fast reactor，the first barrier to prevent the fission product from escaping, is a thin shell structure working under high temperature, high pressure, and nuclear radiation. It needs not only a high strength and stiffness, but also a good integrated function of heat conduction, surface heat transfer, surface drag friction reduction, anti-thermo-mechanical coupling fatigue, resistance to radiation, and etc. In order to realize optimization of the integrated function of miniaturization, lightweight, high power density, and high reliability, it needs a series of novel designs. Aiming at the strategic need of China in development of Lead-Based Cooled Fast Mini-reactor, this project takes the cladding tube of fuel rod as the studying object. Inspired from biomaterial surface micro/nano-structure, combining with bionic design, numerical simulation and experimental study, surface micro/nano-structure of the cladding tube of fuel rod will studied and designed. The multi-objective collaborative optimization of surface heat transfer enhancement, flow drag reduction and anti-thermo-mechanical coupling fatigue will be realized by the bionic design of the surface micro/nano-structure, so that the integrated function in heat transfer, flow drag reduction, and anti-thermo-mechanical coupling fatigue can be greatly enhanced. Once successful, in both theory and practice this project will give an original breakthrough. It is also an important inspiration for the multifunctional design of other heat transfer interface at high temperature.

铅冷快堆燃料棒包壳管属于薄壁壳结构，是防止核裂变产物逸出的第一道屏障。它工作在高温、高压、核辐射等恶劣环境下，不但要求良好的强度和刚度，而且要求良好的导热、界面传热、流动减阻、抗热机耦合疲劳、耐辐射等综合功能。为了实现铅冷快堆小型化、轻量化、高功率密度、高可靠性等综合性能最优，包壳管必须进行一系列创新设计。本项目针对我国微小型铅冷快堆发展的战略需求，以燃料棒包壳管为研究对象，基于生物材料表面微纳结构多功能性启发，以仿生设计、数值模拟和实验研究为主要手段，研究燃料棒包壳管表面微纳结构，通过表面微纳结构仿生设计，实现界面强化传热、流动减阻、抗热机耦合疲劳三个重要功能的多目标协同优化，大幅度提高包壳管与液态铅铋合金的界面传热、流动减阻、抗热机耦合疲劳等综合性能。本项目一旦取得成功，在先进燃料棒包壳管设计方面，无论在理念上还是实践上都是原创性突破。对于其它高温换热界面多功能化设计也是有益启发。

铅冷快堆燃料棒包壳管属于薄壁壳结构，是防止裂变产物逸出的第一道屏障。它工作在高温、高压、核辐射等恶劣环境下，不但要求良好的强度和刚度，而且要求良好的导热、界面传热、流动减阻、抗热机耦合疲劳、耐辐射等综合功能。为了实现铅冷快堆小型化、轻量化、高功率密度、高可靠性等综合性能最优，本项目对铅冷快堆包壳管以及燃料棒组件进行了一系列研究，取得主要成果如下：（1）在温度载荷的作用下，发现铅冷快堆燃料芯块发生了类似“竹节”状的变形，包壳管内侧和外侧均向外膨胀；（2）燃料芯块沿轴向分块后，块与块之间接触区域的温度比整体芯块的温度略低；（3）燃料芯块分块数越大，芯块的最大径向变形越大，但是当燃料芯块的块数在5~40之间时，芯块的最大径向变形基本不再发生改变，芯块的轴向总伸长量随分块数的增加而线性增大；（4）包壳管厚度对燃料芯块区域的温度影响较大，厚度越大包壳管内表面的温度越高，包壳管内外表面的最大径向变形和最大应力也随厚度的增加而增加。（5）气体间隙越大，燃料芯块的温度越高、总变形量越大。气体间隙减小时，芯块-包壳管变形后径向最近距离减小；（6）随着产热功率的升高燃料芯块沿着径向的开裂块数增多，理论分析与实验观察一致。.本项目在执行期间，共完成和发表学术论文30篇，其中国际杂志SCI收录学术论文25篇，参加国际学术会并宣读论文5人次，其中2次会议特邀报告。授权国家发明专利19项，申请并公示国家发明专利9项。各项研究成果远超过预期。2020年获得辽宁省科技进步奖二等奖1项，项目负责人吴成伟2020年获得国际仿生学会杰出会员奖。