一体化压水堆板状燃料元件流道堵塞事故特性分析

Analysis of channel blockage accident of plate-type fuel element in integrated pressurized water reactor

板状燃料元件的冷却剂流道相对狭窄,当出现流道堵塞事故时,可能威胁反应堆的运行安全。针对某采用板状燃料元件的小型船用一体化压水堆,以RELAP5/MOD3.0程序为基础,建立其堆芯热工水力模型,并基于简化的理论分析对模型进行验证;模拟分析单个流道入口处不同的流道堵塞程度,以及组件尺度多个流道同时堵塞的热工水力响应特性。结果表明:在未完全堵塞的情况下,单流道与组件堵塞不会带来严重后果,只是导致安全裕量降低;但单流道入口完全堵塞则有导致堆芯安全参数超限的风险,燃料板最高温大约将比设计报告规定的鼓泡温度限值高80 K左右。

The coolant channel of the plate-type fuel element is relatively narrow.When the channel blockage accident occurs,the operational safety of the reactor may be threatened because the coolant flow reduces and heat transfer deteriorates.For a particular small integrated pressurized water reactor using plate-type fuel element,the thermal-hydraulic model of the core which could be used to simulate blockage accident was improved.Then the transient thermal-hydraulic model of the nuclear power plant was established based on RELAP5/MOD3.0 program.Then the model was verified based on simplified theoretical analysis.Additionally,the authors analyzed the thermal-hydraulic response characteristics of the single channel inlet blockage in different degrees.The results show that even a complete blockage of the single channel inlet will not cause the safety parameters of core to exceed the limit.However,it will lead to a reduction in the safety margin.