核电站乏燃料水池冷却系统虹吸破坏管性能安全分析

摘要

国外核电站的运行经验表明，核电站乏燃料水池冷却（PTR）系统的虹吸破坏管性能存在安全隐患，在某些工况下不能有效阻断虹吸流。本文采用RELAP5软件对国内某典型核电站的虹吸破坏管性能进行安全分析。结果表明，在现有的设计条件下，虹吸破坏管无法及时、有效阻断管道断裂后产生的虹吸流动，乏燃料水池冷却水持续从断裂处泄漏，并导致冷却水管道入口露出水面，从而引起乏燃料水池冷却能力丧失，为核电站安全带来极大风险。进一步分析表明，虹吸流引起的乏燃料水池水位下降幅度受断裂点处距水面的高度差、管道流动阻力和 PT R系统的管道结构3个因素的共同影响；管道流动阻力可有效缓解和降低由管道断裂引发的虹吸流动的危害性。%The feedback from foreign countries shows that the performance of siphon-breaker pipe in some nuclear power plants is insufficient and potential safety risk .In the present study ,numerical simulation was carried out with RELAP5 code to verify the performance of siphon-breaker pipe of PTR system for a typical nuclear power plant . The results show that under the present design siphon-breaker pipe can’ t break the siphon flow in time ,as the results ,the coolant in the spent fuel storage pool will be continuously drained out and can yield the exposure of the coolant pipe inlet ,and the cooling function of the used fuel storage pool is lost ,so that huge safety risk of nuclear power plant is created .The coolant level decreased in spent fuel pool is affected by the height difference between rupture location and free level in pool ,flow resistance and pipe configuration of PTR system .The flow resistance of PTR pipe can alleviate the consequence of siphon flow by pipe rupture .