Modelling of Severe Accident and In-Vessel Melt Retention Possibilities in BWR Type Reactor
Modelling of Severe Accident and In-Vessel Melt Retention Possibilities in BWR Type Reactor
复制标题
BWR 型反应堆中严重事故和容器内熔体滞留可能性的建模
DOI：
10.1155/2018/7162387
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发表时间：
2018
影响因子：
1.1
通讯作者：
E. Ušpuras
中科院分区：
文献类型：
--
作者：
M. Valinčius;T. Kaliatka;A. Kaliatka;E. Ušpuras
核反应堆的严重事故管理策略之一是反应堆压力容器内熔化的真皮滞留。本文研究了容器内滞留(IVR)严重事故管理策略在沸腾堆中的应用。调查是在假设没有注入冷却水的大破口失水的情况下进行的。使用计算机程序RELAP/SCDAPSIM MOD 3.4对事故进行了数值模拟。利用整个反应堆的模型，给出了从大破口到堆芯暴露和升温以及真皮向下水头移动的完整事故序列。为了评价RELAP/SCDAPSIM程序预测热流密度和反应堆压力容器壁温的适用性，对容器外冷却进行了模拟。对不同换热模式的计算结果进行了比较，得出结论：在IVR分析中应采用RELAP/SCDAPSIM中耦合模块实现的换热关联式。为了研究熔池中碎屑分离为氧化层和金属层对下封头壁面换热的影响，进行了分析研究。研究结果表明，聚焦效应显着，在某些极端情况下，反应堆容器的局部热流密度可超过临界热流密度。建议更新现有的碎片中过程的RELAP/SCDAPSIM模型，以便考虑更复杂的现象，并至少考虑氧化物和金属相分离，从而能够评估热通量的局部分布。
One of the severe accident management strategies for nuclear reactors is the melted corium retention inside the reactor pressure vessel. The work presented in this article investigates the application of in-vessel retention (IVR) severe accident management strategy in a BWR reactor. The investigations were performed assuming a scenario with the large break LOCA without injection of cooling water. A computer code RELAP/SCDAPSIM MOD 3.4 was used for the numerical simulation of the accident. Using a model of the entire reactor, a full accident sequence from the large break to core uncover and heat-up as well as corium relocation to the lower head is presented. The ex-vessel cooling was modelled in order to evaluate the applicability of RELAP/SCDAPSIM code for predicting the heat fluxes and reactor pressure vessel wall temperatures. The results of different ex-vessel heat transfer modes were compared and it was concluded that the implemented heat transfer correlations of COUPLE module in RELAP/SCDAPSIM should be applied for IVR analysis. To investigate the influence of debris separation into oxidic and metallic layers in the molten pool on the heat transfer through the wall of the lower head the analytical study was conducted. The results of this study showed that the focusing effect is significant and under some extreme conditions local heat flux from reactor vessel could exceed the critical heat flux. It was recommended that the existing RELAP/SCDAPSIM models of the processes in the debris should be updated in order to consider more complex phenomena and at least oxide and metal phase separation, allowing evaluating local distribution of the heat fluxes.