Statistiska metoder för härledning av indata till säkerhetsanalyser ...

AbstractStatistiska metoder för härledning av indata tillsäkerhetsanalyser inom kärnkraftsområdetStatistical methods for deriving input to nuclear powersafety assessmentsTeknisk- naturvetenskaplig fakultetUTH-enhetenBesöksadress:ÅngströmlaboratorietLägerhyddsvägen 1Hus 4, Plan 0Postadress:Box 536751 21 UppsalaTelefon:018 – 471 30 03Telefax:018 – 471 30 00Hemsida:http://www.teknat.uu.se/studentVidar Hedtjärn SwalingComponents in Swedish nuclear power plants are subject to elaborate testing andmaintenance, all in accordance with the rigorous safety requirements of the SwedishNuclear Power Inspectorate (SKI). Nevertheless, failures sometimes occur thathypothetically might lead to severe accidents. Information on such critical failures iscollected and statistical measures of the rate of occurrence are computed.Today, these computations are carried out using a two-stage Bayesian methoddeveloped by Kurt Pörn. Pörn's method is supposed to be particularly appropriatewhen data is extremely sparse. One objection is that it is conceptuallynon-transparent and therefore should be replaced by a simpler alternative, if there isone.On the basis of an overview given in this thesis, a method proposed by Jussi Vaurioseems to be the most interesting alternative. Its main advantages are fast calculations,transparent mathematical expressions and straightforward replication. Moreover, thenumerical results presented here are quite promising. Hence, though furthercomparisons are necessary, Vaurio's method is proposed as a simpler and in somerespects even better alternative to Pörn's method.Handledare: Anna GabrielssonÄmnesgranskare: Sven Erick AlmExaminator: Elísabet AndrésdóttirISSN: 1650-8319, UPTEC STS06 014