模块式小型压水堆ATWS典型初因事件研究

未能紧急停堆的预期瞬态(ATWS)典型初因事件的选取在大型压水堆核电厂已形成一套完整的方法。由于模块式小型压水堆的结构和设计特点与大型压水堆核电厂差异较大，其ATWS典型事故选取也有所差异，需结合模块式小型压水堆的特点对其ATWS的典型初因事件进行筛选研究。本文从压水堆标准规范出发，结合核电厂ATWS事故的一般要求，采用RELAP5/MOD3.2程序为分析工具，对模块式小型压水堆Ⅱ类瞬态进行了典型ATWS事故的分析，限制准则为，维持反应堆冷却剂系统压力边界的完整性。结果表明，模块式小型压水堆后果最为严重的ATWS初因事件为失电和控制棒失控抽出两个事故，从而最终确定了此类堆ATWS的典型初因事件，为安全分析报告的编制提供了支持。

Study on Typical Initiating Event of ATWS for Small Modular PWR

The method for anticipated transient without scram (ATWS) analysis was completely developed for large scale pressurized water reactor （PWR） plants, especially for the selecting of typical initiating events. For the analysis of ATWS, it is obvious that large scale PWR is quite different from small modular PWR because of different structures and design characteristics, and it is necessary to study the typical initiating events for the safety analyses of these reactors. Based on the standard of PWR and the general requirements for ATWS analysis, the consequences of typical class Ⅱ anticipated transient without scram for small modular PWR were calculated using RELAP5/MOD3.2 code, while the integrity of reactor coolant system was selected as design limit criterion. The results show that for the small modular PWR, the initiating events of ATWS yielding the most severe consequences are the loss of offsite power and control rod withdraw accidents, thereby the typical initiating events were obtained, and it will support to prepare the safety analysis report for small modular PWR.