Volume 2, Issue 3 (March 2005)

    Assessment of Neutron Irradiation-Induced Grain Boundary Embrittlement by Phosphorous Segregation in a Reactor Pressure Vessel Steel

    (Received 11 June 2004; accepted 26 October 2004)

    Published Online: 2005

    CODEN: JAIOAD

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    Abstract

    The materials used were two sorts of reactor pressure vessel steels (RPVSs), which contain different amounts of impurity phosphorous (P) and copper (Cu). The specimens for Charpy V-notch impact tests and Auger electron spectroscopy (AES) were irradiated in the Japan Materials Test Reactor (JMTR) at 290°C up to fluences of 6 × 1021 and 1 × 1024 n/m2 using a multi-division temperature control capsule which enables removal of a part of the sub-capsules during operation of the reactor.

    Neutron irradiation resulted in a significant shift in the ductile-brittle transition temperature (DBTT) accompanied by a large irradiation hardening in the high P and high Cu steel. The AES measurements following the irradiations revealed that almost no phosphorous segregation occurred at grain boundaries. The DBTT shifts by neutron irradiation were reasonably interpreted in terms of a so-called hardening mechanism. The SEM observations of the fractured surface indicated that a very small amount of grain boundary fracture was induced at the irradiation conditions, and resultantly no grain boundary embrittlement was observed.

    Based on the results of irradiation experiments as well as long-term thermal aging experiments beyond 16 000 h, neutron irradiation-induced grain boundary embrittlement is considered to rarely happen to the RPVS that contains 110 wppm of phosphorous.


    Author Information:

    Kimura, A
    Professor, Graduate Student, and Research Associate, Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto,

    Shibata, M
    Professor, Graduate Student, and Research Associate, Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto,

    Kasada, R
    Professor, Graduate Student, and Research Associate, Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto,

    Fujii, K
    Senior Researcher, Institute of Nuclear Safety System, Inc., Mikata, Fukui,

    Fukuya, K
    Senior Researcher, Institute of Nuclear Safety System, Inc., Mikata, Fukui,

    Nakata, H
    Senior Researcher, Institute of Nuclear Safety System, Inc., Mikata, Fukui,


    Stock #: JAI12398

    ISSN: 1546-962X

    DOI: 10.1520/JAI12398

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    Author
    Title Assessment of Neutron Irradiation-Induced Grain Boundary Embrittlement by Phosphorous Segregation in a Reactor Pressure Vessel Steel
    Symposium Effects of Radiation on Materials: 22nd International Symposium, 2004-06-10
    Committee E10