STP1170: Evaluation of the Recovery Annealing of the Reactor Pressure Vessel of NPP Nord (Greifswald) Units 1 and 2 by Means of Subsize Impact Specimens

    Ahlstrand, R
    Office manager, Imatra Power Company (IVO), Vantaa,

    Klausnitzer, EN
    Deputy director and department manager, Siemens AG, Power Generation Group, KWU, Erlangen,

    Lange, D
    Deputy department manager and main department manager, Energiewerke Nord AG, Greifswald,

    Leitz, C
    Deputy director and department manager, Siemens AG, Power Generation Group, KWU, Erlangen,

    Pastor, D
    Deputy department manager and main department manager, Energiewerke Nord AG, Greifswald,

    Valo, M
    Senior research scientist, Technical Research Centre (VTT), Espoo,

    Pages: 23    Published: Jan 1993


    Abstract

    In 1988 and 1990, the reactor pressure vessels of Units 1 and 2, respectively, of the Greifswald nuclear power station were subjected to heat treatment at 475°C for annealing of irradiation effects. To demonstrate the effect of annealing and to evaluate a new postannealing transition temperature of vessel base metal and weld metal, boat samples were removed by means of electric discharge machining (EDM) from the (unclad) inner surface of the vessel. From these samples, micronotched bar impact test specimens were fabricated and tested at different temperatures. Transition curves were evaluated from the results. By means of correlation tests, the transition temperatures evaluated from the micro-specimen tests are converted to standard Charpy-V transition temperatures. Results are available for the weld metal of Unit 1 after annealing. The transition temperature TK is lower than the value calculated by the designer of the plant. Specimens removed from Unit 2 before and after annealing are in preparation.

    Keywords:

    WWER 440, reactor pressure vessel, irradiation effects, annealing, notched bar impact test, subsize specimens


    Paper ID: STP24785S

    Committee/Subcommittee: E10.07

    DOI: 10.1520/STP24785S


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