The feasibility of small size specimens for testing of environmentally assisted cracking of irradiated materials and of materials under irradiation in reactor core

Aki Toivonen, Pekka Moilanen, Mika Pyykkönen, Seppo Tähtinen, Rauno Rintamaa, Timo Saario

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

    Abstract

    Environmentally assisted cracking (EAC) of core materials has become an increasingly important issue of downtime and maintenance costs in nuclear power plants. Small size specimens are necessary in stress corrosion testing of irradiated materials because of difficulties in handling high dose rate materials and because of restricted availability of the materials. The drawback of using small size specimens is that in some cases they do not fulfil the requirements of the relevant testing standards. Recently VTT has developed J-R testing with irradiated and non-irradiated sub size 3 PB specimens, both in inert and in LWR environments. Also, a new materials testing system which will enable simultaneous multiple specimen testing both in laboratory conditions and in operating reactor core is under development. The new testing system will utilize Charpy and sub size 3 PB specimens. The feasibility study of the system has been carried out using different materials. Fracture resistance curves of a Cu-Zr-Cr alloy are shown to be independent of the specimen geometry and size, to some extent. Results gained from tests in simulated boiling water reactor (BWR) water are presented for sensitized SIS 2333 stainless steel. The experimental results indicate that the size of the plastic zone or stress triaxiality must be further studied although no significant effect on the environmentally assisted crack growth rate was observed. (
    Original languageEnglish
    Title of host publication23. MPA seminar
    Subtitle of host publicationSafety and reliability of plant technology with special emphasis on nuclear technology
    Place of PublicationStuttgart
    PublisherMaterials Testing Institute University of Stuttgart MPA
    Number of pages9
    Volume1
    Publication statusPublished - 1997
    MoE publication typeB3 Non-refereed article in conference proceedings
    Event23. MPA-Seminar - Stuttgart, Germany
    Duration: 1 Oct 19972 Oct 1997

    Conference

    Conference23. MPA-Seminar
    CountryGermany
    CityStuttgart
    Period1/10/972/10/97

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