铅冷快堆SGTR工况下蒸汽泡在堆内的迁移行为及其对堆芯物理特性影响的研究

Lead-cooled fast reactor (LFR) is one of the most promising generation-IV reactors. After steam generator tube rupture(SGTR) accident occurred, supercritical water will inject into primary coolant. Steam produced by the interaction of supercritical water with high temperature lead will cause void effect when reaching reactor core with flow of primary coolant. Though the net void coefficient is negative, the local void coefficient can still be positive due to the 3-D characteristic of migration, shape and distribution. After considering surface tension, wall adhesion and compressibility, steam bubble migration model was developed based on Lagrange coordinates. Momentum and energy transfer between two phase fluids is accomplished through the projection and coupling between the Lagrange particle and Euler mesh, which help to accomplish the dispersed steam bubble migration simulation in traditional system analysis code for the first time. After validation with experimental data, steam bubble migration behavior in reactor core for SVBR75/100 fast reactor after SGTR was investigated with nuclear thermal coupled code SAC-LFR/HNHEXK. Transient response of effective multiplication factor Keff and void reactivity coefficient were obtained, and the effect on core neutron kinetic characteristic of steam bubble migration would be investigated based on the computational results. Research on the migration model of steam bubble and its effect on neutron kinetic characteristic has certain academic significance, which can also provide certain reference in accident analysis of LFR.

铅冷快堆是非常有发展前景的第四代堆堆型之一。铅冷快堆发生蒸汽发生器传热管破裂事故后，二回路水喷射进入一回路与冷却剂相互作用产生蒸汽，蒸汽随冷却剂的流动进入堆芯会造成空泡效应。虽然铅堆总空泡系数为负，但由于气泡的迁移速率、形态、分布等具有典型的三维特征，因此局部空泡系数仍可能为正。本课题考虑蒸汽泡的表面张力、粘性力、可压缩性，开发出基于拉格朗日坐标系的蒸汽泡迁移模型，通过与欧拉网格映射耦合进行两相流体间的动量及能量传递，首次实现了在系统程序中对离散蒸汽泡迁移行为的模拟。利用实验数据验证之后，应用铅堆核热耦合程序SAC-LFR/HNHEXK开展SVBR75/100快堆SGTR工况下蒸汽泡在堆内迁移行为瞬态计算，获得有效增殖系数、空泡反应性系数的瞬态分布，评价蒸汽泡迁移对堆芯物理特性的瞬态影响。本课题中对蒸汽泡迁移模型的研究具有一定的学术意义，课题研究成果对铅堆的事故分析也具有一定的参考价值。

铅冷快堆是非常有发展前景的第四代核能系统堆型。铅冷快堆发生蒸汽发生器传热管破裂事故后，二回路水喷射进入一回路与冷却剂相互作用产生蒸汽，蒸汽随冷却剂的流动进入堆芯会造成空泡效应，影响堆芯物理特性与安全特性。本课题研究铅冷快堆SGTR工况下水蒸汽随一回路冷却剂的流动进入堆芯后蒸汽泡的迁移行为，计算堆芯空泡反应性系数的三维分布特性，评价蒸汽泡的迁移对堆芯物理特性、安全特性的影响。在本项目的资助下，发表了SCI论文4篇，EI论文1篇，会议论文1篇。培养已毕业博士生1名，硕士生1名，在读博士生1名，在读硕士生2名。获得北京市科技进步奖1项，协会科技进步奖2项。本项目的研究成果对于提高铅堆的设计及安全分析能力有重要意义。