RPV侧边破口条件下堆外蒸汽爆炸计算分析

针对实际过程中更有可能发生的压力容器（RPV）侧边破口条件开展蒸汽爆炸计算分析。根据经济合作与发展组织（OECD）发布的现象识别与重要度排序表（PIRT），选取堆外蒸汽爆炸敏感性分析参数，使用MC3D软件建立三维局部破口和二维环状破口几何模型，对影响计算结果的重要参数（破口尺寸、堆坑水位、破口位置、触发条件、液柱碎化和液滴碎化模型）开展RPV侧边破口条件下敏感性分析，获得最恶劣计算工况条件。敏感性分析结果表明，在大破口失水事故（LBLOCA）工况下，当堆坑处于满水位、RPV发生二维侧边环状破口、接触堆坑侧壁面时触发蒸汽爆炸、采用CONST模型和Classical模型时，堆坑侧壁面的压力载荷计算结果最为保守，对堆坑和安全壳完整性威胁最大。 

Analysis of Ex-Vessel Steam Explosion under RPV Side Break Cases

The calculation and analysis of steam explosion were carried out for the pressure vessel (RPV) side breach conditions that are more likely to occur in the actual process. According to the Phenomena Identification and Ranking Table (PIRT) issued by Organization for Economic Cooperation and Development (OECD), the sensitivity analysis parameters for ex-vessel steam explosion are selected. By establishing 3D local break and 2D circular break geometric models with MC3D, the sensitivity analysis under RPV side break conditions is carried out for the important parameters affecting the calculation results (break size, pit water level, break position, trigger conditions, liquid column fragmentation and droplet fragmentation model), and the worst calculation conditions are obtained. The sensitivity analysis results show that under the condition of large break loss of coolant accident (LBLOCA), when the reactor pit is at full water level, 2D side circular break occurs in RPV, steam explosion is triggered when contacting the reactor pit side wall, and CONST model and Classical model are adopted, the calculation results of pressure load on the reactor pit side wall are the most conservative and pose the greatest threat to the integrity of the reactor pit and containment.