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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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

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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