STP1502: Using Subsize Impact Bend Specimens for Estimation of Irradiation and Re-Irradiation Embrittlement of VVER RPV Steels

    Nikolaev, Yu. A.
    Lab Head and Senior Research Scientist, Russian Research Center “Kurchatov Institute,” IRMT, Moscow,

    Nikolaeva, A. V.
    Lab Head and Senior Research Scientist, Russian Research Center “Kurchatov Institute,” IRMT, Moscow,

    Pages: 17    Published: Jan 2009


    Abstract

    Results of impact bend tests of subsize Charpy V-notch-type (CVN) specimens are used in Russia for monitoring both re-irradiation embrittlement of the first generation of VVER-440 (including VVER-440∕179 and VVER-440∕230, i.e., projects B-179 and B-230) reactor pressure vessel (RPV) steels and irradiation embrittlement of VVER-440∕213 RPV steels. For the first generation of VVER-440 RPVs, no surveillance program was foreseen and only subsize specimens (5 by 5 by 27.5 mm and 3 by 4 by 27 mm) can be manufactured from samples taken from the inner surface of the RPV for radiation embrittlement monitoring. For VVER-440∕213 RPVs, 80 % of the surveillance specimens are irradiated with a lead factor greater than 20. Only four specimens of base metal and four specimen halves of weld seam material are irradiated with a lead factor less than 3. Taking into account that full-size (10 by 10 by 55 mm) CVN specimens were used in surveillance programs, using subsize specimens enables to solve the flux effect problem for VVER-440∕213 RPV beltline materials and ensure representativity of surveillance programs. Application of subsize specimens for the estimation of radiation embrittlement requires developing a correlation between transition temperature values evaluated using test results of standard (full-size) and subsize CVN specimens. Such a correlation is discussed.

    Keywords:

    reactor pressure vessel, radiation embrittlement, ductile-to-brittle transition temperature, subsize impact bend specimens, specimen reconstitution


    Paper ID: STP48722S

    Committee/Subcommittee: E10.01

    DOI: 10.1520/STP48722S


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