Nuclear reactor safety (NRS) and the branch accident analysis (AA) constitute proven technologies: these are based on, among the other things, long lasting research and operational experience in the area of water cooled nuclear reactors (WCNR). Large break loss of coolant accident (LBLOCA) has been, so far, the orienting scenario within AA and a basis for the design of reactors. An incomplete vision for those technologies during the last few years is as follows: Progress in fundamentals was stagnant, namely in those countries where the WCNR were designed. Weaknesses became evident, noticeably in relation to nuclear fuel under high burn-up. Best estimate plus uncertainty (BEPU) techniques were perfected and available for application. Electronic and informatics systems were in extensive use and their impact in case of accident becomes more and more un-checked (however, quite irrelevant in case of LBLOCA). The time delay between technological discoveries and applications was becoming longer. The present paper deals with the LBLOCA that is inserted into the above context. Key conclusion is that regulations need suitable modification, rather than lowering the importance and the role of LBLOCA. Moreover, strengths of emergency core cooling system (ECCS) and containment need a tight link.

核反应堆安全（NRS）和分支事故分析（AA）构成了行之有效的技术：这些技术除其他外，是基于在水冷核反应堆（WCNR）领域的长期研究和运行经验。迄今为止，冷却剂事故的大量破坏损失（LBLOCA）一直是机管局的定向方案，也是反应堆设计的基础。过去几年中对这些技术的不完整愿景如下：基本原理的进展停滞不前，即在那些设计了WCNR的国家。弱点变得明显，特别是在高度燃尽的情况下，与核燃料有关。最佳估计加不确定度（BEPU）技术已完善并可供应用。电子和信息系统已得到广泛使用，并且它们在事故情况下的影响变得越来越难以控制（但是，对于LBLOCA而言，这是无关紧要的）。技术发现与应用之间的时间延迟越来越长。本文讨论了插入到上述上下文中的LBLOCA。关键结论是，法规需要进行适当的修改，而不是降低LBLOCA的重要性和作用。此外，应急堆芯冷却系统（ECCS）和安全壳的优势需要紧密的联系。而不是降低LBLOCA的重要性和作用。此外，应急堆芯冷却系统（ECCS）和安全壳的优势需要紧密的联系。而不是降低LBLOCA的重要性和作用。此外，应急堆芯冷却系统（ECCS）和安全壳的优势需要紧密的联系。