STP909

    Surveillance Programs and Irradiation Embrittlement Research of the Loviisa Nuclear Power Plant

    Published: Jan 1986


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    Abstract

    The surveillance programs of Loviisa 1 and 2 nuclear power plants consist of irradiations of Charpy V-notch, Charpy-size three-point bend, and tensile specimens. The specimens are located outside the core barrel. The program consists of six sets of irradiation capsules that are taken out according to a special schedule.

    The results from the first surveillance tests from Loviisa 1 showed that the shift in transition temperature (both Charpy-V and crack-opening displacement) was higher than expected. These results introduced a modification to the original withdrawal schedule of the surveillance capsules. The subsequent test results confirmed the shift in transition temperature.

    In addition to the normal surveillance program, new surveillance capsules have been placed into both reactors before and after the core modification including round compact tension (CT) specimens. Parallel programs to validate the reliable use of small specimens for fracture toughness measurements and a special instrumented impact tester have been conducted.

    The accuracy of the fluence measurements has been improved by the implementation of some novel procedures.

    To study the amelioration of radiation embrittlement, an annealing study was carried out using the broken halves of the Charpy bars from surveillance testing.

    Keywords:

    radiation embrittlement, surveillance program, fracture toughness, neutron dosimetry, pressure vessels, nuclear reactor materials, chemical composition, heat treatment, radiation effects, pressure vessel steels


    Author Information:

    Ahlstrand, R
    Head of Materials Engineering Office, Imatran Voima Power Company, Helsinki,

    Törrönen, K
    Head of Materials Technology Section, Technical Research Centre of Finland, Metals Laboratory, Espoo,

    Valo, M
    Senior research officers, Technical Research Centre of Finland, Reactor Laboratory, Espoo,

    Bärs, B
    Senior research officers, Technical Research Centre of Finland, Reactor Laboratory, Espoo,


    Paper ID: STP23028S

    Committee/Subcommittee: E10.08

    DOI: 10.1520/STP23028S


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