Study of tearing behaviour of a PWR reactor pressure vessel lower head under severe accident loadings

Koundy, V.; Caroli, C.; Nicolas, L.; Matheron, P.; Gentzbittel, J.M.; Coret, Michel

doi:10.1016/j.nucengdes.2008.03.005

Cited by 19 publications

(4 citation statements)

References 14 publications

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“…Some simplified numerical analysis were made in order to simulate these tests [7][8][9][10]. From this established fact, a lot of tests were carried out in order to characterize the French material behaviour (16MND5) according to its steel grades [11].…”

Section: Pvp2009-77258mentioning

confidence: 99%

Unstable Crack Propagation Under Severe Accident Scenario Conditions in a Pressurized Water Reactor

Tardif

Coret

Combesure

2009

Volume 5: High Pressure Technology; Nondestructive Evaluation Division; Student Paper Competition

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In the case of a severe accident scenario of a pressurized water reactor which includes cracking of the vessel bottom head, it is crucial to predict the leak rate and hence the crack size for the ex-vessel accident management. We present an experimental framework to analyze the crack propagation under such severe conditions for different 16MND5 French nuclear steel grades. An original experimental setup has been designed in order to perform bi-axial tests (tensile load independent of internal pressure) at high temperatures (1180K – 1280K) on tubular test specimens. The temperature loading and the mechanical loading can be set to reproduce the stress distribution of the hemispherical vessel bottom head submitted to an internal pressure. Moreover, the test was designed to be easily transposable to the real structure in terms of crack propagation and depressurization thanks to an energy based scaling methodology. We observed the crack initiation and propagation with two high speed digital cameras. Force, internal pressure, displacement and temperature fields were also measured and synchronized with the optical measurements. The different creep stages are observed and characterized. The crack propagation and opening history have been measured. During crack initiation and propagation stages, the depressurization can be correlated with the crack geometry. Finally, the setup has been designed in order to validate future numerical analysis.

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Section: Pvp2009-77258mentioning

confidence: 99%

Unstable Crack Propagation Under Severe Accident Scenario Conditions in a Pressurized Water Reactor

Tardif

Coret

Combesure

2009

Volume 5: High Pressure Technology; Nondestructive Evaluation Division; Student Paper Competition

Self Cite

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“…Previous structural experiments of RPV under the artificial melting-core accident conditions, such as Lower Head Failure (LHF) 4 and Failure of Reactor Vessel Retention (FOREVER), 5 have shown the creep failure as one of the predominant failure mechanisms endangering the structural integrity of RPVs. 6 Therefore, a thorough understanding of creep mechanisms and behaviors of RPV materials at extremely high temperatures is essential for successful implementation of IVR. Particularly, for structural integrity analysis under IVR conditions (high temperature, high pressure, and steep temperature gradient), it requires an accurate constitutive model to faithfully describe the deformation and failure/life of the RPV material altogether.…”

Section: Introductionmentioning

confidence: 99%

“…Such high‐temperature gradient coupled with the remaining pressure will pose a serious threat to the structural integrity of RPVs. Previous structural experiments of RPV under the artificial melting‐core accident conditions, such as Lower Head Failure (LHF) 4 and Failure of Reactor Vessel Retention (FOREVER), 5 have shown the creep failure as one of the predominant failure mechanisms endangering the structural integrity of RPVs 6 . Therefore, a thorough understanding of creep mechanisms and behaviors of RPV materials at extremely high temperatures is essential for successful implementation of IVR.…”

Section: Introductionmentioning

confidence: 99%

Creep behavior and life prediction of a reactor pressure vessel steel above phase‐transformation temperature via a deformation mechanism‐based creep model

Wang

Zheng

et al. 2023

Fatigue Fract Eng Mat Struct

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For nuclear power generation as a carbon‐neutral energy source, in‐vessel retention (IVR) must be implemented to maintain the structural integrity of nuclear reactor pressure vessel (RPV) for more than 72 h under severe accidental conditions. This technology requires accurate prediction of creep deformation and life of RPV material being operated under pressure and extremely high‐temperature gradient. The current work develops a simplified deformation‐mechanism‐based true‐stress (DMTS) model for creep behavior/life‐prediction of SA508 Gr.3 steel, a typical RPV material, above the phase transformation temperatures (800–1000°C). This model is used to evaluate the time to specific creep strain (t3% and t5%) and rupture (tr), in comparison with popular empirical methods such as Orr–Sherby–Dorn (OSD) and Larson–Miller (LM). The simplified DMTS model achieves an excellent agreement with the experimental observations. The controlling deformation mechanisms are also discussed by metallurgical examinations, which provide the physical premise for the model development and application.

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“…In this paper, our objective is to study more particularly the initiation and quasi-static (or stable) Mode I crack propagation in pressure vessel steel (16MND5) at 1173 K [4]. In the course of this work, cracking tests were carried out on sidegrooved CT specimens.…”

Section: Introductionmentioning

confidence: 99%

Stable crack propagation in steel at 1173K: Experimental investigation and simulation using 3D cohesive elements in large-displacements

Tardif

Combescure

Coret

et al. 2010

Engineering Fracture Mechanics

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International audienceThis paper deals with the numerical simulation of a stable crack propagation experiment at 1173K in a 16MND5 steel. At this temperature, the material is viscoplastic. A cohesive zone model is formulated in order to simulate the rupture of a CT specimen. A large displacement 3D cohesive element with eight nodes is implemented in the finite element code ABAQUS. The associated traction–separation law is of Tvergaard and Hutchinson type, in which an hardening slope has been added. This hardening simulates the material strengthening associated to the increasing strain rate in front of the crack tip when crack tip starts to propagate.We show that in this case the form of the cohesive law has great impact on the simulated propagation velocity

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Study of tearing behaviour of a PWR reactor pressure vessel lower head under severe accident loadings

Cited by 19 publications

References 14 publications

Unstable Crack Propagation Under Severe Accident Scenario Conditions in a Pressurized Water Reactor

Unstable Crack Propagation Under Severe Accident Scenario Conditions in a Pressurized Water Reactor

Creep behavior and life prediction of a reactor pressure vessel steel above phase‐transformation temperature via a deformation mechanism‐based creep model

Stable crack propagation in steel at 1173K: Experimental investigation and simulation using 3D cohesive elements in large-displacements

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