LOCA后安全壳碎片对压水堆燃料组件的压降影响试验研究

Experimental Study on Effect of Containment Debris on Pressure Drops of PWR Fuel Assembly after LOCA

为研究压水堆核电厂失水事故(LOCA)后杂质在堆芯燃料组件内的沉积现象及压头损失,本试验搭建相应台架,分析了极限工况下碎片在组件中的分布和堵塞情况,定量化评估LOCA后安全壳内碎片对燃料组件压降的影响。结果表明,碎片几乎都堆积在组件下半段尤其是下管座;碎片量相同时,碎片同时添加方案比依次添加方案造成的压降更大;化学沉淀物对碎片床有压实效应,可造成更显著的压头损失;即使极限工况仍有足够的冷却剂进入堆芯排出余热。

To study the impurity accumulation phenomenon and corresponding impact on head loss through fuel assembly after loss of coolant accident in Pressurized Water Reactors(PWRs), the test platform is established and the distribution and blockage of debris in the assembly in the worst condition were analyzed, and the effect of the debris in the containment after LOCA on the pressure drops across a fuel assembly is quantatively evaluated. All test results indicated that almost all debris were captured on the lower half of the fuel assembly, especially on bottom nozzle. The head loss resulted from debris added with concurrent addition method was higher than that with sequential addition method with the same debris amount;The chemical precipitate could compact the debris bed, resulting in a great effect on head loss;Enough coolant could be provided into the core for cooling even in worst condition.