Abstract
The objective of this study is to find out the impact of instrumentation and control (I&C) components on the availability of I&C systems in terms of sensitivity analysis using Bayesian network. The analysis has been performed on I&C architecture of reactor protection system. The analysis results would be applied to develop I&C architecture which will meet the desire reliability features and save cost. RPS architecture unavailabilityP(x=0)and availabilityP(x=1)were estimated to6.1276E-05and9.9994E-01for failure (0) and perfect (1) states, respectively. The impact of I&C components on overall system risk has been studied in terms of risk achievement worth (RAW) and risk reduction worth (RRW). It is found that circuit breaker failure (TCB), bi-stable processor (BP), sensor transmitter (TR), and pressure transmitter (PT) have high impact on risk. The study concludes and recommends that circuit breaker bi-stable processor should be given more consideration while designing I&C architecture.
Highlights
The last two decades are the witnesses of rapid development of digital technology in the nuclear industry
instrumentation and control (I&C) architecture for reactor protection system (RPS), consisting of 4 channels, has been proposed for research reactor and its Bayesian network model has been constructed for reliability analysis
The unavailability of reactor trip (X) (P(x = 0)) is of an interest parameter and will be used for importance analysis; it will be denoted by QRPS(λ)
Summary
The last two decades are the witnesses of rapid development of digital technology in the nuclear industry. Though instrumentation and control (I&C) architecture of nuclear power plants has been established to a certain level, yet it is design dependent and not standardized for all the industry. Holbert and Lin highlighted the need of improved methods for monitoring, control, and diagnostics due to economic constraints and applied fuzzy logic to enhance plant availability by assessing equipment condition [1]. It is essential to find which architecture will perform better among digital, analog, or hybrid designs. Digital I&C still has to win confidence because advent of digital I&C systems in nuclear power plants has created new challenges for safety analysis and it is necessary to quantify the risk impact of digital systems specially related to software, processing unit (CPU), and common cause failures [2].
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