On Reliability Analysis Of Digital Control System For Level Of Steam Generator

It is necessary to account for couplings between digital I&C systemand controlled objects; couplings between the basic components, tasks anddata communication of digital I&C system and time dependencies tocompletely analyze and assess the reliability of digital instrument andcontrol (I&C) system. However, the traditional event tree/fault tree methodcan only describe the static relationship of the system. So it is necessary tostudy dynamic modeling methodologies. On the other hand, there lackuniversally accepted modeling methods and benchmark system to evaluatesoftware failure modes and their system level effects for digital I&Csystem. Taking steam generator which is one of the important equipmentof the nuclear power plant as the research object, this paper establishes thebenchmark system of digital control and protection system for level ofsteam generator and researches the corresponding reliability modeling andanalysis mthodologies which is of referent significance for the reliabilityanalysis of digital control and protection system for level of steamgenerator.Details are as follows:1. Analyze the process operating characteristics of steam generatorand the control laws of digital control and protection system of level forsteam generator.2. Research the failure modes of the key components of the digitalcontrol and protection system of level for steam generator and their systemlevel effects.3. Use dynamic flowgraph methodology to model the reliabilitymodel of the digital control and protection system of level for steam generator based on related control laws.4. Take low-low level and high-high level of steam generator as topevents and use deductive method to analyze the constructed model. Thenprime implications of two top events of this system are respectivelyobtained. The failure rates of top events are acquired by using the faultempirical data. The above analysis shows that the constructed model bydynamic flowgraph methodology can be uesd for several top events.