**2. Related work**

Zeller et al. [5] proposed a combined approach of Markov chain and component fault tree to analyze the complex software-controlled system in the automotive domain. The authors have addressed safety and reliability in modular form. However, authors have missed to validate the result and failed to express reliability accuracy in percentage.

Nidhin et al. [6] presented a survey for understanding radiation effects in SRAM-based FPGAs for implementing I&C of NPP. Authors have found that for implementing NPP with I&C in SRAM-based FPGAs, the effect of radiation issue is a major concern. To reduce radiation-related issues some components, which have SRAM-based FPGAs, must keep outside of reactor containment building (RCB). However, the authors have failed to discuss the case study.

Jia et al. [7] proposed an approach for the identification of vulnerabilities present in elements that affect the reliability of digital instrumentation and control system (DI&C) software life cycle using Bayesian network. A reliability demonstration of safety-critical software (RDSS) integrates the claim-argument-evidence (CAE) and sensitivity to estimate the reliability of the system. However, there is a limitation with BN that has no time constraints and dynamic property. Authors have missed addressing the reliability with validation from the real-time dataset.

Rejzek and Hilbes [8] proposed system-theoretic process analysis (STPA) for design verification and risk analysis of digital I&C of NPP. This method is considered as a prominent approach for analysis of the I&C system theoretically as the authors claim. However, the authors are not very much sure, that method correct result.

Torkey et al. [9] proposed a reliability improvement framework of the digital reactor protection system by transforming reliability block diagram to Bayesian belief network (BBN). The proposed method gives the highest availability as a result and found some modules are riskier than others of I&C. However, authors claim that it gives the highest availability but missed to validate the result with real-time data.

Kumar et al. [3] proposed a framework for predicting the reliability of the safety-critical and control system using the Bayesian update methodology. The authors have validated the result with real-time data of 12 safety-critical control systems of NPP. However, the result obtained is purely based on the failure data, if failure data is unavailable then it is difficult to predict the reliability.

Mamdikar et al. [10] devise a framework for reliability analysis, performance analysis that maps unified modified language (UML) to Petri net. The proposed framework is validated with 32 safety-critical systems of NPP. However, Petri net has a state space explosion problem as a system grows gradually, so it is not a generalized approach.

### *Reliability Analysis of Instrumentation and Control System: A Case Study of Nuclear Power… DOI: http://dx.doi.org/10.5772/intechopen.101099*

Nayak et al. [11] proposed a methodology called assessment of passive system reliability (APSRA) is used to estimate the reliability of the passive isolation condenser system of the Indian advanced heavy water reactor (AHWR). In this methodology, reliability is estimated through PSA treatment using generic data of the component. A classical fault tree analysis is used to find the root cause of the critical parameter, which leads to failure. However, the authors have failed to validate the result.

Kumar et al. [12] proposed a safety analysis framework that maps UML into the state-space model as Petri net of the safety-critical system of NPP. In this methodology, the result is validated on 29 different safety-critical systems of NPP. However, the authors have used Petri net that has a state space explosion problem.

Tripathi et al. [13] proposed a noble methodology dynamic reliability analysis of the passive decay heat removal system of NPP using Petri net. The authors have validated the estimated reliability based on the data available using fault tree analysis. Most of the system does not have such type data, and then it is difficult to validate the result with missing failure data. Therefore, this methodology may not applicable for every safety-critical system of NPP.

Buzhinsky and Pakonen [14] proposed an automated symmetry breaking approach for checking failure tolerance of I&C system. With this method a fewer failure combination has to be checked. The complex structure paired with various specifications has to be checked under failure assumptions, which is the limitation of this work.

Singh et al. [15] proposed a system modeling strategy for design verification of I&C of nuclear power plant using Petri net and converting PN into Markov chain. In this approach, verification is validated on real-time data. However, Petri net has a state-space explosion problem, in such circumstances, it is difficult to handle complex systems, which is the limitation of the work.

Xi et al. [16] proposed a test strategy based on the random selection of logic path by which provides reliability estimation and is used for control system testing in digital control software systems in the NPP. However, the authors have not been addressed and validated the reliability evaluation.

Bao et al. [17] proposed hazard analysis for identifying common cause failure of digital I&C using redundancy guided system in NPP. To conduct using redundancy guided systems, theoretic hazard analysis a modularized approach was applied. This method is helpful to remove casual effects of potential single points of failure that exist in I&C. However, authors have missed addressing the reliability analysis using this methodology in NPP.

Gupta et al. [1] proposed a method for stability analysis and steady-state analysis of the safety system of NPP using Petri net. The stability and steady-state were estimated and validated, however, authors have missed estimating reliability. The authors have to correlate stability with reliability. Further, this methodology is applicable only for discrete-time systems.
