Abstract The Fukushima Daiichi NPP (Nuclear Power Plant) accident pointed out the hydrogen explosion issue as one of the main problems that can affect the NPP containment integrity. During a severe accident scenario, the hydrogen combustion can occur and lead to containment integrity failure, since it generates local and global pressure and heat spikes. Such topic was analysed in several research programs addressed all around the world. An important series of test campaigns was done in OECD/NEA WGAMA (Organisation for Economic Co-operation and Development/Nuclear Energy Agency Working Group on Analysis and Management of Accidents) program called THAI (Thermal-hydraulics, Hydrogen, Aerosol and Iodine). The THAI goal is to simulate several phenomena related on hydrogen and Fission Product behaviour in the containment to obtain data relevant for the code benchmarking and validation. Therefore, theoretical analyses are needed, in order to obtain a reliable prediction of the accidental scenario. The facility allows to investigate safety relevant effects under thermal-hydraulics conditions of severe accidents. The experiments performed cover from hydrogen deflagration to iodine and aerosol behaviour under different thermal-hydraulics conditions. Three representative experiments were chosen from the THAI campaign to be modeled and simulated using the MELCOR code with versions 2.1 and 2.2 and compare the results with the experimental ones. This work aims to assess the MELCOR code capability pointing out on the limitation in simulating the hydrogen deflagration and underling possible method to reduce their effect on the simulate results. The benchmarks were addressed with old version of MELCOR however the new version presented slightly different results due to the modification in the parametric model and the default sensitivity coefficients.

中文翻译：

---

使用 MELCOR 代码版本 2.1 和 2.2 分析 THAI 1 氢爆燃

摘要 福岛第一核电站事故指出氢爆炸问题是影响核电站安全壳完整性的主要问题之一。在严重事故情况下，氢气燃烧可能发生并导致安全壳完整性故障，因为它会产生局部和全局压力和热尖峰。世界各地的几个研究项目都分析了这个话题。在 OECD/NEA WGAMA（经济合作与发展组织/核能机构事故分析和管理工作组）计划中进行了一系列重要的测试活动，称为 THAI（热液压、氢、气溶胶和碘）。THAI 的目标是模拟与安全壳中氢和裂变产物行为相关的几种现象，以获得与代码基准测试和验证相关的数据。因此，需要进行理论分析，以获得对事故情景的可靠预测。该设施允许调查严重事故的热工水力条件下的安全相关影响。实验涵盖了从氢爆燃到碘和不同热工水力条件下的气溶胶行为。从 THAI 活动中选择了三个具有代表性的实验，使用版本 2.1 和 2.2 的 MELCOR 代码进行建模和模拟，并将结果与​​实验结果进行比较。这项工作旨在评估 MELCOR 代码能力，指出模拟氢爆燃的局限性，并提出可能的方法以减少它们对模拟结果的影响。使用旧版本的 MELCOR 解决了基准测试，但是由于参数模型和默认灵敏度系数的修改，新版本的结果略有不同。