数字化安全级DCS紧急停堆系统共因失效分析

以2oo3架构数字化安全级分布式控制系统（DCS）紧急停堆系统为研究对象,采用Markov方法对其建立可靠性模型,分别计算并对比了考虑共因失效和不考虑共因失效2种情况下紧急停堆系统的拒动概率,同时对系统拒动概率相对于共因失效因子变化的敏感性进行了重点分析。结果表明,拒动概率随着共因失效因子的增加而变大,因此,在系统设计中需采取有效措施对冗余系统的共因失效进行控制,降低共因失效因子,从而提高紧急停堆系统的可靠性。 

Common Cause Failure of Digital Safety Level DCS Emergency Shutdown System

This paper takes the digital safety level DCS emergency shutdown system which used 2-out-of-3 architecture as the research object, and establishes the reliability model of the system by the method of Markov. The average probability of failure on demand, as so called the PFD_avg, under two cases of common cause failure and non common cause failure consideration are calculated and compared. In addition, it turns out that the PFDavg changes to be bigger with the increasing of the factor of common cause failure. Thus, in order to decrease the factor of common cause failure, it is necessary to control the common cause failure by some effective measures when designing the system to improve the reliability of RTS.