Metoda za procjenu parametara modela kvarova sa zajedničkim uzorkom u vjerojatnosnim sigurnosnim analizama

doctoral thesis

• Title (english): Method of Common Cause Failure Model Parameters Estimation for Probabilistic Safety Analyses
• Author: Igor Vuković
• Mentor: Vladimir Mikuličić (mentor)
• Committee member: Nenad Debrecin (predsjednik povjerenstva)
• Committee member: Vladimir Mikuličić (član povjerenstva)
• Committee member: Srete Nikolovski (član povjerenstva)
• Committee member: Neven Elezović (član povjerenstva)
• Committee member: Dubravko Pevec (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; (Department of Energy and Power Systems); Zagreb
• Defense date and country: 2009-01-16, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering
• Universal decimal classification (UDC): 621.3 - Electrical engineering

Abstract

Sigurnost tehničkih sustava u današnje je vrijeme važan predmet razmatranja zbog sve izraženije uloge tehnoloških postupaka u modernom društvu, zbog sve većih posljedica kvarova postrojenja i njihove sve veće složenosti. Posljednjih su tridesetak godina u tehničkoj inženjerskoj praksi sve prisutnije u primjeni vjerojatnosne sigurnosne analize. Stablom kvara sustava matematički se modeliraju različite vrste kvara analiziranog sustava. Statistička neovisnost osnovnih događaja, od kojih je izgrađeno stablo kvara, nije prihvatljiva za vrstu događaja zvanih kvarovi sa zajedničkim uzrokom. To su kvarovi koji istovremeno pogađaju dvije ili više istovrsnih redundantnih komponenti, a imaju isti ishodišni uzrok. Radi se o uzrocima koji predstavljaju ostatnu, ponekad teško uhvatljivu, ovisnost među komponentama, čiji mehanizmi nisu eksplicitno ugrađeni u logičke modele postrojenja. Disertacija razmatra ovisne kvarove i njihove mehanizme, izlaže se fenomenologija kvarova sa zajedničkim uzrokom i predstavljaju njihovi matematički modeli. Govori se, nadalje, o pogonskoj povijesti kvarova sa zajedničkim uzrokom, opisuju se strategije za provedbu periodičkih provjera ispravnosti opreme, uvodi se koncept tzv. vektora događaja, opisuje postupak za njihovu izgradnju na temelju podataka izvornog tehničkog sustava i njihovo naknadno preslikavanje na analizirani sustav. U disertaciji se uvodi i razrađuje metoda za proračun procjenitelja parametra kvarova sa zajedničkim uzrokom, za dva u praksi najčešće rabljena matematička modela, model grčkog alfabeta i model alfa-faktora, u obliku točkastih vrijednosti i razdioba vjerojatnosti za slijednu i naizmjeničnu strategiju ispitivanja opreme. Razdiobe vjerojatnosti određuju se primjenom Bayesovog teorema uvažavanjem pogonskog iskustva. Metoda je provedena na demonstracijskom primjeru, jednu vrstu opreme u nuklearnoj elektrani koji je normalno u pripravnosti, te su dodatno prikazani rezultati primjene metode na razini cijelog VSA-modela nuklearne elektrane. U načelu predloženi je analitički postupak primjenjiv za bilo koji tehnički sustav. Disertacija se zaključuje najvažnijim opažanjima i razmatranjima proizišlim iz istraživanja, razrade metode i njezine primjene u stvarnom VSA-modelu te ukazuje na neka područja u kojima bi se mogao usmjeriti nastavak istraživanja.

Abstract (english)

Nowadays technical system’s safety is a significant issue due to widespread usage of technological processes in modern society, increasing consequences of facilities' failures and their increased importance. Over the last thirty years the probabilistic safety analyses have been increasingly applied in technical engineering practice. Various failure modes of system of concern are mathematically and explicitly modelled by means of fault tree structure. Statistical independence of basic events, from which the fault tree is built, is not acceptable for an event category referred to as common cause failures. These are the failures which simultaneously affect two or more redundant components of the same type, and have the same underlying root cause. These are the causes that represent the residual, sometimes difficult to catch, dependence among the components, whose mechanisms are not explicitly built into the facilities' logical models. The doctoral thesis deals with dependent failures and their mechanisms, displays common cause failure phenomenology and presents their mathematical models. Furthermore, the thesis describes operational history of common cause failures and the strategies for implementation of periodical testing for standby components. The concept of so called event impact vector was introduced and the procedure for their development, based on operating experience from the source system, was defined. Per that procedure, each source impact vector is specialised, modified to reflect the likelihood of occurrence of the event in the plant of interest. The doctoral thesis proposes and elaborates a method for common cause failure model parameters estimation, for two in practice most often used mathematical models, multiple Greek letter model and alpha-factor model, in the form of both point estimates and probability distributions, for staggered and non-staggered testing scheme. Uncertainty distributions are estimated by Bayesian approach based on operating history. The method has been applied in demonstration example, on selected piece of standby equipment in nuclear power plant for a specific failure mode. In addition, the method has been implemented on the level of whole nuclear power plant PSA model and selected results were presented. In principle, analytical approach proposed in this thesis is applicable to any technical system. The doctoral thesis ends up with the most important observations and considerations as an outcome of the research, method development, and its implementation in concrete PSA model, and points to some areas in which the further research activities can be focused.

• Keywords: vjerojatnosna sigurnosna analiza; kvarovi sa zajedničkim uzrokom; model grčkog alfabeta; model alfa-faktora; procjenitelji parametara; neodređenost parametara; Bayesova analiza; sigurnost; tehnički sustav
• Keywords (english): probabilistic safety analysis; common cause failure; multiple Greek letter model; alpha-factor model; parameter estimators; parameter uncertainty; Bayesian analysis; safety; technical system
• Language: croatian
• URN:NBN: urn:nbn:hr:168:573704
• Project: Number: 036-0361590-1589; Title: Nuklearne elektrane za održivu proizvodnju električne energije; Leader: Danilo Feretić; Jurisdiction: Croatia; Funder: MZOS; Funding stream: ZP
• Study programme: Title: Doctoral study programme "Electrical Engineering and Computing"; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, po-dručje tehničkih znanosti (doktor/doktorica znanosti, po-dručje tehničkih znanosti)
• Catalog URL: http://lib.fer.hr/cgi-bin/koha/opac-detail.pl?biblionumber=33438
• Type of resource: Text
• Extent: 186 str.
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2020-03-25 12:27:14