小型自然循环铅冷快堆无保护最热组件局部堵流瞬态分析

Transient Analysis on Unprotected Partial Flow Blockage of Hottest Fuel Assembly for A Small Natural Circulation Lead-Cooled Fast Reactor

铅冷快堆内液态重金属的腐蚀作用严重制约铅冷快堆技术发展。基于程序ATHLET建立100MW小型模块化自然循环铅冷快堆SNCLFR-100一回路主冷却系统模型,对无保护最热组件局部堵流事故开展瞬态热工安全分析。结果显示,当阻塞率β达到0.6时,最热组件内冷却剂流量将降为额定流量的50%左右,而最热棒包壳最高温度将达到650℃。当β达到0.9时,最热组件内冷却剂流量将降为额定流量的12.6%左右,包壳最高温度将超过包壳材料熔点1400℃,此时最热组件内将出现包壳熔化现象。

Corrosion of cladding and structural materials by liquid lead or LBE is one of the key issues restricting the development of lead-cold fast reactor. A primary cooling system analytical model of 100 MWth small modular natural circulation lead-cooled fast reactor named SNCLFR-100 is established with ATHLET code, and the unprotected transient of partial flow blockage of the hottest fuel assembly was analyzed. The results of analysis indicate that the mass flow rate of the hottest fuel assembly will drop to about 50% of the rated value when the blocking rate β reaches 0.6, while the maximum temperature of the hottest pin cladding will reach 650℃. When β reaches 0.9, the mass flow rate of the hottest fuel assembly will fall to about 12.6% of the rated value, and the maximum temperature of the hottest pin cladding will exceed the cladding material melting point 1400℃, and cladding melting will occur in the hottest fuel assembly.