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受冷却剂丧失事故(LOCA)喷放流体冲击产生的保温纤维碎片是安全壳地坑滤网堵塞的潜在碎片源。本文以空气为介质模拟大破口失水事故(LBLOCA)下介质喷放压力场及物理过程,通过高速摄影视频回放及碎片统计,分析双壁盒式保温结构受高能流体冲击时的破坏规律。实验结果表明,内壁为双壁盒式保温模块最薄弱部分;高能流体冲击下,模块连接机构失效使得模块与管道分离,内壁暴露于高速气流中被撕裂引起保温碎片释放。基于保温结构破坏机理分析,提出采用不锈钢捆扎带可有效减小碎片量,并通过实验对改进方案进行了验证。
Fibrous pieces of insulating fibers resulting from a LOCA bleed fluid impact are a potential source of debris for clogging of containment pit screens. In this paper, the pressure field and the physical process of medium ejection under LBLOCA were simulated by using air as medium, and the damage rules of double-walled box-type thermal insulation structure subjected to high-energy fluid impact were analyzed by high-speed video playback and debris statistics. The experimental results show that the inner wall is the weakest part of the double-walled thermal insulation module. Under the impact of high-energy fluid, the failure of the module connection mechanism makes the module separate from the pipeline, and the inner wall is exposed to high-speed airflow and is torn to release the thermal insulation debris. Based on the analysis of the failure mechanism of thermal insulation structure, it is proposed that the use of stainless steel strapping can effectively reduce the amount of debris, and the improvement program has been verified through experiments.