Abstract In the current design, the blanket plays an important role of transporting heat and breeding Tritium. It is very necessary to analyze the accident of the blanket. In this study, the RELAP5 model of the Water Cooled Ceramic Breeder blanket (WCCB) was established. The numerical simulation of the in-vessel loss of coolant accident (LOCA) on the first wall (FW) were conducted. The instability phenomenon was detected and analyzed for the first time. In 1-channel-break LOCA, the instability phenomenon occurs because of the subcooled boiling. The pressure amplitude of the break downstream is almost 2MPa. The mass flow rate amplitude is around 0.5kg/s. This large oscillation amplitude may damage the FW and cause more serious consequences. In 15-channel-break case, as the pressure is reduced to very lower level, the saturation temperature decreases, and the nucleate boiling instead of the subcooled boiling occurs. The instability phenomenon doesn’t occur. The results show that the current design of WCCB cannot remain safe in the large break LOCA. In order to avoid further damage, relevant safety facilities need to be studied.

中文翻译：

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水冷毯失水事故中的流动失稳现象

摘要 在目前的设计中，毯子起着输送热量和繁殖氚的重要作用。对毛毯事故进行分析是非常有必要的。在本研究中，建立了水冷陶瓷育种毯（WCCB）的 RELAP5 模型。对第一壁（FW）的船内冷却剂损失事故（LOCA）进行了数值模拟。首次检测并分析了不稳定现象。在1通道断裂LOCA中，由于过冷沸腾而出现不稳定现象。破裂下游压力幅值接近2MPa。质量流量幅度约为0.5kg/s。这种较大的振荡幅度可能会损坏FW并造成更严重的后果。在15通道断裂情况下，随着压力降低到非常低的水平，饱和温度降低，并且发生核态沸腾而不是过冷沸腾。不会出现不稳定现象。结果表明，当前的WCCB设计在大断口LOCA中无法保持安全。为了避免进一步的损害，需要研究相关的安全设施。