Crack initiation testing of thimble tube material under PWR conditions to determine a stress threshold for IASCC

Rik-Wouter Bosch, Marc Vankeerberghen, Robert Gérard, Frédéric Someville, Serguei Gavrilov

    Research outputpeer-review


    IASCC (Irradiation Assisted Stress Corrosion Cracking) crack initiation tests have been carried out on thimble tube material retrieved from a Belgian PWR. The crack initiation tests were carried out by constant load testing of thimble tube specimens at different stress levels. The time-to-failure was determined as a function of the applied stress to find a stress threshold under which no stress corrosion cracking will take place. Over a period of four years, more than 40 specimens have been tested with doses ranging from 45 to 80 dpa at stress levels between 40% and 70% of the irradiated yield stress. Fracture occurred at all stress levels (but not all specimens) although the time-to-failure increased with decreasing stress. The results show that intergranular cracking was the main fracture mode in all failed O-rings. Three of six 80 dpa O-rings subjected to 40 and 45 % of the yield stress didn't fail after six months of testing. Based on these results and a comparison with literature data, an apparent stress limit for IASCC could be estimated at 40% of the irradiated yield stress.
    Original languageEnglish
    Pages (from-to)112-121
    JournalJournal of Nuclear Materials
    Issue number06
    StatePublished - Mar 2015

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