Determination of the time to failure curve as a function of stress for a highly irradiated AISI 304 stainless steel after constant load tests in simulated PWR water environment

C. Pokor, J.-P. Massoud, M. Wintergerst, Aki Toivonen, Ulla Ehrnstén, Wade Karlsen

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    Abstract

    The structures of Reactor Pressure Vessel Internals are subjected to an intense neutron flux. Under these operating conditions, the microstructure and the mechanical properties of the austenitic stainless steel components change. In addition, these components are subjected to stress of either manufacturing origin or generated under operation. Cases of baffle bolts cracking have occurred in CP0 Nuclear Power Plant units. The mechanism of degradation of these bolts is Irradiation-Assisted Stress Corrosion Cracking. In order to obtain a better understanding of this mechanism and its principal parameters of influence, a set of stress corrosion tests (mainly constant load tests) were launched within the framework of the EDF project "Lower Core Internals," using materials from a CHOOZ A baffle corner (SA 304). These tests aim to quantify the influence on IASCC of the applied stress, temperature and environment (primary water, higher lithium concentration, inert environment) for an irradiation dose close to 30 dpa. A curve showing time to failure as a function of the stress was determined. The shape of this curve is consistent with the few data that are available in the literature. A stress threshold of about 50 % of the yield strength value at the test temperature has been determined, below which cracking in that environment seems unlikely. After irradiation this material is sensitive to intergranular fracture in a primary environment, but also in an inert environment (argon) at 340°C. The tests also showed a negative effect of increased lithium concentration on the time to failure and on the stress threshold.
    Original languageEnglish
    Title of host publicationFontevraud 7
    Subtitle of host publicationContribution of Materials Investigation to Improve the Safety and Performance of LWRs, Avignon, France, 26-30.9.2010
    Number of pages18
    Publication statusPublished - 2010
    MoE publication typeNot Eligible

    Fingerprint

    Stainless steel
    Water
    Irradiation
    Bolts
    Lithium
    Neutron flux
    Stress corrosion cracking
    Austenitic stainless steel
    Pressure vessels
    Nuclear power plants
    Dosimetry
    Yield stress
    Argon
    Loads (forces)
    Corrosion
    Degradation
    Mechanical properties
    Temperature
    Microstructure

    Keywords

    • corrosion
    • PWR
    • irradiation
    • stainless steel

    Cite this

    Pokor, C., Massoud, J-P., Wintergerst, M., Toivonen, A., Ehrnstén, U., & Karlsen, W. (2010). Determination of the time to failure curve as a function of stress for a highly irradiated AISI 304 stainless steel after constant load tests in simulated PWR water environment. In Fontevraud 7: Contribution of Materials Investigation to Improve the Safety and Performance of LWRs, Avignon, France, 26-30.9.2010
    Pokor, C. ; Massoud, J.-P. ; Wintergerst, M. ; Toivonen, Aki ; Ehrnstén, Ulla ; Karlsen, Wade. / Determination of the time to failure curve as a function of stress for a highly irradiated AISI 304 stainless steel after constant load tests in simulated PWR water environment. Fontevraud 7: Contribution of Materials Investigation to Improve the Safety and Performance of LWRs, Avignon, France, 26-30.9.2010. 2010.
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    title = "Determination of the time to failure curve as a function of stress for a highly irradiated AISI 304 stainless steel after constant load tests in simulated PWR water environment",
    abstract = "The structures of Reactor Pressure Vessel Internals are subjected to an intense neutron flux. Under these operating conditions, the microstructure and the mechanical properties of the austenitic stainless steel components change. In addition, these components are subjected to stress of either manufacturing origin or generated under operation. Cases of baffle bolts cracking have occurred in CP0 Nuclear Power Plant units. The mechanism of degradation of these bolts is Irradiation-Assisted Stress Corrosion Cracking. In order to obtain a better understanding of this mechanism and its principal parameters of influence, a set of stress corrosion tests (mainly constant load tests) were launched within the framework of the EDF project {"}Lower Core Internals,{"} using materials from a CHOOZ A baffle corner (SA 304). These tests aim to quantify the influence on IASCC of the applied stress, temperature and environment (primary water, higher lithium concentration, inert environment) for an irradiation dose close to 30 dpa. A curve showing time to failure as a function of the stress was determined. The shape of this curve is consistent with the few data that are available in the literature. A stress threshold of about 50 {\%} of the yield strength value at the test temperature has been determined, below which cracking in that environment seems unlikely. After irradiation this material is sensitive to intergranular fracture in a primary environment, but also in an inert environment (argon) at 340°C. The tests also showed a negative effect of increased lithium concentration on the time to failure and on the stress threshold.",
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    Pokor, C, Massoud, J-P, Wintergerst, M, Toivonen, A, Ehrnstén, U & Karlsen, W 2010, Determination of the time to failure curve as a function of stress for a highly irradiated AISI 304 stainless steel after constant load tests in simulated PWR water environment. in Fontevraud 7: Contribution of Materials Investigation to Improve the Safety and Performance of LWRs, Avignon, France, 26-30.9.2010.

    Determination of the time to failure curve as a function of stress for a highly irradiated AISI 304 stainless steel after constant load tests in simulated PWR water environment. / Pokor, C.; Massoud, J.-P.; Wintergerst, M.; Toivonen, Aki; Ehrnstén, Ulla; Karlsen, Wade.

    Fontevraud 7: Contribution of Materials Investigation to Improve the Safety and Performance of LWRs, Avignon, France, 26-30.9.2010. 2010.

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    TY - GEN

    T1 - Determination of the time to failure curve as a function of stress for a highly irradiated AISI 304 stainless steel after constant load tests in simulated PWR water environment

    AU - Pokor, C.

    AU - Massoud, J.-P.

    AU - Wintergerst, M.

    AU - Toivonen, Aki

    AU - Ehrnstén, Ulla

    AU - Karlsen, Wade

    N1 - Project code: 36811 Proc. on a CD-ROM, ISBN N/A

    PY - 2010

    Y1 - 2010

    N2 - The structures of Reactor Pressure Vessel Internals are subjected to an intense neutron flux. Under these operating conditions, the microstructure and the mechanical properties of the austenitic stainless steel components change. In addition, these components are subjected to stress of either manufacturing origin or generated under operation. Cases of baffle bolts cracking have occurred in CP0 Nuclear Power Plant units. The mechanism of degradation of these bolts is Irradiation-Assisted Stress Corrosion Cracking. In order to obtain a better understanding of this mechanism and its principal parameters of influence, a set of stress corrosion tests (mainly constant load tests) were launched within the framework of the EDF project "Lower Core Internals," using materials from a CHOOZ A baffle corner (SA 304). These tests aim to quantify the influence on IASCC of the applied stress, temperature and environment (primary water, higher lithium concentration, inert environment) for an irradiation dose close to 30 dpa. A curve showing time to failure as a function of the stress was determined. The shape of this curve is consistent with the few data that are available in the literature. A stress threshold of about 50 % of the yield strength value at the test temperature has been determined, below which cracking in that environment seems unlikely. After irradiation this material is sensitive to intergranular fracture in a primary environment, but also in an inert environment (argon) at 340°C. The tests also showed a negative effect of increased lithium concentration on the time to failure and on the stress threshold.

    AB - The structures of Reactor Pressure Vessel Internals are subjected to an intense neutron flux. Under these operating conditions, the microstructure and the mechanical properties of the austenitic stainless steel components change. In addition, these components are subjected to stress of either manufacturing origin or generated under operation. Cases of baffle bolts cracking have occurred in CP0 Nuclear Power Plant units. The mechanism of degradation of these bolts is Irradiation-Assisted Stress Corrosion Cracking. In order to obtain a better understanding of this mechanism and its principal parameters of influence, a set of stress corrosion tests (mainly constant load tests) were launched within the framework of the EDF project "Lower Core Internals," using materials from a CHOOZ A baffle corner (SA 304). These tests aim to quantify the influence on IASCC of the applied stress, temperature and environment (primary water, higher lithium concentration, inert environment) for an irradiation dose close to 30 dpa. A curve showing time to failure as a function of the stress was determined. The shape of this curve is consistent with the few data that are available in the literature. A stress threshold of about 50 % of the yield strength value at the test temperature has been determined, below which cracking in that environment seems unlikely. After irradiation this material is sensitive to intergranular fracture in a primary environment, but also in an inert environment (argon) at 340°C. The tests also showed a negative effect of increased lithium concentration on the time to failure and on the stress threshold.

    KW - corrosion

    KW - PWR

    KW - irradiation

    KW - stainless steel

    M3 - Conference article in proceedings

    BT - Fontevraud 7

    ER -

    Pokor C, Massoud J-P, Wintergerst M, Toivonen A, Ehrnstén U, Karlsen W. Determination of the time to failure curve as a function of stress for a highly irradiated AISI 304 stainless steel after constant load tests in simulated PWR water environment. In Fontevraud 7: Contribution of Materials Investigation to Improve the Safety and Performance of LWRs, Avignon, France, 26-30.9.2010. 2010