Determination of prime implicants by differential evolution for the dynamic reliability analysis of non-coherent nuclear systems

Maio, Francesco Di; Baronchelli, Samuele; Vagnoli, Matteo; Zio, Enrico

doi:10.1016/j.anucene.2016.12.018

Cited by 9 publications

(7 citation statements)

References 27 publications

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“…The most evident difference between DETs and static ETs is that while ETs are constructed by expert analysts that draw their branches based on success/failure criteria set by the analysts, in DETs, these are spooned by a software that embeds the (deterministic) models simulating the plant dynamics and the (stochastic) models of components failure. Naturally, the DET generates a number of scenarios much larger than that of the classical static FT/ET approaches, so that the a posteriori retrieval of information can become quite burdensome and complex [125][126][127]. Another challenge is related to the relevant effort in terms of computational time required for generating a large number of time-dependent accident scenarios by means of Monte Carlo techniques that are typically employed to deeply and thoroughly explore the entire system state-space, and to cover in principle all the possible combinations of events over long periods of time.…”

Section: Integration Of Passive Systems Into Dynamic Psamentioning

confidence: 99%

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Reliability Assessment of Passive Safety Systems for Nuclear Energy Applications: State-of-the-Art and Open Issues

et al. 2021

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Passive systems are fundamental for the safe development of Nuclear Power Plant (NPP) technology. The accurate assessment of their reliability is crucial for their use in the nuclear industry. In this paper, we present a review of the approaches and procedures for the reliability assessment of passive systems. We complete the work by discussing the pending open issues, in particular with respect to the need of novel sensitivity analysis methods, the role of empirical modelling and the integration of passive safety systems assessment in the (static/dynamic) Probabilistic Safety Assessment (PSA) framework.

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Section: Integration Of Passive Systems Into Dynamic Psamentioning

confidence: 99%

“…Thus, the "a posteriori" retrieval of information can be quite burdensome and difficult. In this view, artificial intelligence techniques could be embraced to address the problem [125][126][127]; iii.…”

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confidence: 99%

Reliability Assessment of Passive Safety Systems for Nuclear Energy Applications: State-of-the-Art and Open Issues

et al. 2021

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“…A Multiple Value Logic (MVL) scheme presented in (Bellaera et al, 2018) has been adopted to describe the N = 100 accidental scenarios generated by random sampling the stochastic (discrete) time (t) of occurrence of component failures, their (discrete) magnitude (m). The random components failures of a generated scenario are represented in an MVL sequence vector that contains the discretized time and magnitudes values and the order (ord) of occurrence in the sequence: [mCP,tCP,ordCP,mCV1,tCV1,ordCV1,mCV2,tCV2,ordCV2,mBV,tBB,ordBV,mSV1,tSV1,ordSV1,mSV2,tSV2,ordSV2] (Di Maio et al, 2017), where, for all components CP, CV1, CV2; BV, SV1, SV2, the discretization of the time (t) and magnitude (m) are as follows:…”

Section: Accidental Scenarios Generationmentioning

confidence: 99%

Integrated deterministic and probabilistic safety assessment of a superconducting magnet cryogenic cooling circuit for nuclear fusion applications

Bellaera

Bonifetto

Maio

et al. 2020

Reliability Engineering & System Safety

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The most promising configuration of a nuclear energy fusion system is the tokamak, the largest of which, called ITER, is under construction in Cadarache, France, which uses a complex system of superconducting magnets to generate a field of several tesla (T), aimed at confining the plasma in the toroidal chamber where nuclear fusion reactions occur. For industrial development, the safety of nuclear fusion systems has to be proved and verified by a systematic analysis of operational transients and accidental conditions. Although the final aim of fusion reactors is to reach steady state operation, present-day tokamaks present complex dynamic features, as their operation is based on the transformer principle with a subset of the superconducting magnets operating in a pulsed mode, to inductively generate plasma currents of the order of several MA. We adopt the framework of Integrated Deterministic and Probabilistic Safety Assessment (IDPSA), for identifying the component failures that may cause a Loss-Of-Flow-Accident (LOFA) in the cooling circuit of a superconducting magnet for fusion applications. Post-processing of the simulated scenarios for the identification of the abnormal transients is performed in an unsupervised manner resorting to a spectral clustering approach embedding a Fuzzy-C Means (FCM) that is compared with an Extended Symbolic Aggregate approXimation (ESAX) from the literature that also resorts to the FCM for the classification.The proposed approach turns out to be more efficient than ESAX in the identification of clusters and "prototypical states" of abnormal system behavior. Results show that none of the identified scenarios (even those leading to a LOFA) are critical for the ITER central solenoid module integrity, in the mode of operation considered.

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“…In such circumstances, traditional methods, for example, based on minimal cut sets analysis, cannot be applied, whereas Figure 7: Example of dynamic system behavior at 80% . dynamic reliability methods need to be applied for the identification of the PIs [33,34].…”

Section: Prime Implicants Identificationmentioning

confidence: 99%

“…Among these 18 available features, we search for those that are optimal for clustering the 64381 scenarios in Near Misses and safe scenarios. We resort to a wrapper framework [37,38], whereby a modified binary differential evolution (MBDE) search engine [33,39] searches candidate groups of features sets that are fed to a -means clustering algorithm [40]; eventually, the wrapper evolves so that among these candidate groups, the group retained is that which makes the -means clustering algorithm perform best (most compact and separate clusters). The idea behind the wrapper approach is shown in Figure 12.…”

Section: Features Selection the Identification Of The Near Missesmentioning

confidence: 99%

Risk-Based Clustering for Near Misses Identification in Integrated Deterministic and Probabilistic Safety Analysis

Maio

Vagnoli

Zio

2015

Science and Technology of Nuclear Installations

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In integrated deterministic and probabilistic safety analysis (IDPSA), safe scenarios and prime implicants (PIs) are generated by simulation. In this paper, we propose a novel postprocessing method, which resorts to a risk-based clustering method for identifying Near Misses among the safe scenarios. This is important because the possibility of recovering these combinations of failures within a tolerable grace time allows avoiding deviations to accident and, thus, reducing the downtime (and the risk) of the system. The postprocessing risk-significant features for the clustering are extracted from the following: (i) the probability of a scenario to develop into an accidental scenario, (ii) the severity of the consequences that the developing scenario would cause to the system, and (iii) the combination of (i) and (ii) into the overall risk of the developing scenario. The optimal selection of the extracted features is done by a wrapper approach, whereby a modified binary differential evolution (MBDE) embeds aK-means clustering algorithm. The characteristics of the Near Misses scenarios are identified solving a multiobjective optimization problem, using the Hamming distance as a measure of similarity. The feasibility of the analysis is shown with respect to fault scenarios in a dynamic steam generator (SG) of a nuclear power plant (NPP).

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Determination of prime implicants by differential evolution for the dynamic reliability analysis of non-coherent nuclear systems

Cited by 9 publications

References 27 publications

Reliability Assessment of Passive Safety Systems for Nuclear Energy Applications: State-of-the-Art and Open Issues

Reliability Assessment of Passive Safety Systems for Nuclear Energy Applications: State-of-the-Art and Open Issues

Integrated deterministic and probabilistic safety assessment of a superconducting magnet cryogenic cooling circuit for nuclear fusion applications

Risk-Based Clustering for Near Misses Identification in Integrated Deterministic and Probabilistic Safety Analysis

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