HPR1000非能动堆腔注水冷却系统事故缓解能力评估

华龙一号（HPR1000）设计了堆腔注水冷却系统（CIS）以实现严重事故期间熔融物的堆内滞留（IVR），该系统分为能动与非能动两列子系统，其中非能动CIS应对的是全厂断电（SBO）始发的严重事故工况。本文对非能动CIS的事故缓解能力进行评估。首先开发了下封头熔池换热计算程序并予以验证，使用MAAP程序对SBO严重事故序列及SBO叠加不同尺寸一回路破口始发的严重事故序列进行计算，并结合熔池换热计算程序得到不同事故序列下的压力容器外壁面最大热流密度，进而评估不同事故序列下非能动CIS的有效性。评估结果表明，非能动CIS可有效应对SBO始发的严重事故序列以及SBO叠加一回路破口尺寸小于60 mm始发的严重事故序列，实现IVR策略。评估结果可应用于HPR1000的严重事故管理。

Assessment on Accident Mitigation Capability of HPR1000 Passive Cavity Injection System

HPR1000 is designed with cavity injection system (CIS) which can realize in-vessel retention during severe accidents. CIS includes active and passive serials, among which passive CIS is designed to mitigate severe accident induced by station black-out (SBO). The accident mitigation capability of passive CIS was evaluated in this paper. A calculation code for molten pool heat transfer in lower head was developed and validated. Severe accidents initiated by SBO and SBO plus primary loop break with different break sizes were calculated by MAAP code, the maximum heat flux of pressure vessel outer surface under different severe accident sequences was calculated together with the validated code, and then the validity of passive CIS was evaluated for the above accident sequences. The results indicate that passive CIS can mitigate severe accidents initiated by SBO or SBO plus primary loop break with equivalent break size smaller than 60 mm and achieve the IVR strategy. The results can be used in severe accident management for HPR1000.