ADS 次临界堆液态金属铅铋流动与强化传热机理研究

Accelerator driven subcritical system (ADS) has been listed as the energy strategy to deal with the long-lived nuclear waste for China's large-scale development of nuclear power. As liquid lead-bismuth alloy (LBE) has good neutron and thermal overload performance, it is preferred as the windowless target material and coolant. Its flow and heat transfer characteristics in the special conditions of high temperature, high-energy proton beam bombardment and high power density of nuclear heat, which is the key scientific issues of the coupling of the accelerator and target, the coupling of the target and blanket, and the advanced second-loop technology, has become an international hot spot. The self-developed series of liquid metal experimental loop, high-temperature non-contact ultrasonic velocimetry, the method of combining experiments and numerical simulation, are used to study the turbulence models for heavy metals’ flow and heat transfer. The high temperature LBE target free surface formation mechanism and stability of evolution are explored. The correlation of flow pressure drop and flow rate, the flow rate and fuel rods wall friction coefficient, heat transfer correlation and heat transfer coefficient, for the blanket LBE under the special conditions of complex clearance flow, the dramatic changes of nuclear thermal power density along the axial direction and so on, are discussed. The field temperature of the complex flow within the heat exchanger of high temperature LBE and high-pressure helium gas, flow rate and flow resistance, and the empirical correlation of enhanced heat transfer performance are studied. The results can lay the foundation for the design and construction of ADS reactor and the development of key technologies.

加速器驱动次临界堆(ADS)已列为我国大规模发展核电处理长寿命核废料的能源战略。液态铅铋合金(LBE)由于具有良好的中子与载热性能，首选作为无窗靶材料和冷却剂，其在高温、高能质子束流轰击、高功率密度核热等特殊条件下的流动与传热特性是加速器与靶、靶与包层耦合及先进二回路技术领域的关键科学问题，已成为国际研究热点。本项目运用自主研发的系列液态金属实验回路、高温非接触超声波测速技术，采用实验验证与数值模拟相结合的方法，研究适合液态重金属流动与传热的湍流模型，探索高温LBE靶区自由表面形成演变规律与稳定机理，获取复杂间隙流道、核热功率密度沿轴向剧烈变化等特殊条件下包层内LBE流动压降与流速关联式、流速与燃料棒壁面磨擦系数关系、换热关联式和换热系数，探究换热器复杂流道内高温LBE与高压氦气双流场温度、流速与流动阻力、强化换热性能的经验关联式，为ADS堆设计建造与关键技术的发展奠定基础。

本培育项目相关研究成果发表SCI收录论文10篇(其中JCR-I区2篇，II区1篇)，核心期刊论文6篇，获得国家发明专利4项，培养研究生3名。搭建了超汽化强化换热回路(HVL-I)、压力水强化换热回路(PWHL-II)和高温液态铅铋(LBE)流动与换热模拟实验回路等实验系统三套。在国际上最先进的大型铅铋回路上首次开展了ADS次临界堆堆芯模拟燃料组件(1:1)的高温液态金属铅铋流动与传热特性实验与数值模拟验证，获得不同热功率和流量下的温度场数据、子通道局部对流换热系数和模拟燃料组件整体对流换热特性，给出了复杂间隙流道、核热功率密度沿轴向剧烈变化等特殊条件下包层内LBE流动压降与流速关联式、流速与燃料棒壁面磨擦系数关系、换热关联式和换热系数。实验结果表明Borishanski传热模型更适于ADS次临界堆堆芯燃料组件的传热设计与分析，研究结果已应用于第四代先进核裂变能系统－铅及铅合金冷却反应堆的热工设计、传热分析与方案评估；发展了用于超汽化强化换热实验研究的激光诱导荧光、粒子图像跟踪、高速摄影与微距摄影相结合的定量观察与测量技术，创新性地开展了反应堆堆内部件高热流条件下的超汽化强化换热实验与数值模拟研究，该成果相关技术和实验结果已应用于研制国际热聚变实验反应堆ITER的水冷屏蔽包层第一壁的超汽化强化换热部件；在国际上首次探索性地开展了极高热流条件下水基纳米流体超汽化强化换热与临界热流实时监测实验，研究结果表明采用该技术可使反应堆高热流部件的临界热流平均提高180%，最大提高230%，该冷却技术被核能界评价为“是ITER和第四代核裂变堆堆内高热流部件最有可能发展的先进候选冷却方案”。结合实验研究中相关关键技术问题的解决，申请并获得了“一种基于声波传感器的反应堆堆内部件临界热流实时监测方法”、“一种驱动高温液态金属循环流动冷却堆内部件的方法”、“高温强磁场下液态金属边界层速度分布的测量方法”、“一种用于液态重金属冷却堆的换料机夹具装置”等4项国家发明专利。