Fuel failure and fission gas release in high burnup PWR fuels under RIA conditions

Fuketa, Toyoshi; Sasajima, Hideo; Mori, Yukihide; Ishijima, Kiyomi

doi:10.1016/s0022-3115(97)00173-6

Cited by 64 publications

(28 citation statements)

References 2 publications

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“…The blister formation mecanism in PWR irradiated cladding tubes is the formation of cold spots due to oxide spallation, that trigger hydrogen thermo-diffusion [13]. The blister geometry observed in Zircaloy-4 cladding tubes after reactor exposure is typically 1 mm to 5 mm in diameter and about half the thickness of the cladding tube ( Figure 1 in addition to the analysis of the blisters reported in [12,13,14,15,16,17,18,19]). The formation of blisters on unirradiated Cold-Worked-Stress-Relieved (CWSR) Zircaloy-4 specimens was experimentally achieved in the laboratory by applying a nickel coating on a given area of the sample surface to accelerate locally the hydrogen uptake during gaseous charging [14,20,21,22].…”

Section: Matmentioning

confidence: 96%

“…Remark 3: some blisters were also grown in Zircaloy-2 in Singh et al [10] but their characterization was not reported. In the case of PWRs, the effect of blisters on the cladding mechanical 3 resistance was observed in the 90's in studies dealing with Reactivity Initiated Accidents (RIA) performed in research reactors such as CABRI [11] or NSRR [12]. It was also observed after burst and tensile tests on irradiated cladding tubes [13].…”

Section: Matmentioning

confidence: 99%

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Formation and characterization of hydride blisters in Zircaloy-4 cladding tubes

Ménibus

Auzoux

Dieye

et al. 2014

Journal of Nuclear Materials

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This article is focused on the formation of hydride blisters in zirconium alloys an experimental and theoritical standpoint, and their characterization in terms of morphology, hydrides crystallographic phases, hardness and hydrogen concentration. An experimental setup was developed to grow hydride blisters on pre-hydrided Zircaloy-4 cladding tubes by thermo-diffusion. The thermal conditions were optimized based on thermo-diffusion calculations, that take into account the hysteresis in the hydrogen solubility limit, to obtain a high blister growth rate. Micro X-Ray Diffraction (XRD), nano-hardness and Elastic Recoil Detection Analysis (ERDA) showed that the blisters contain a hydrogen gradient, with pure δ-hydride phase close to the external surface over one third of the blister depth. thermo-diffusion * Tel.: +33 1 69 08 39 43; e-mail: arthur.hellouin-de-menibus@cea.fr 1 calculations showed these half thickness blisters should grow in only a few days in PWR conditions. Eventually, the Diffusion Equilibrium Threshold (DET) was defined as a criterion that limits the blister growth, and emphasizes that the hysteresis in the hydrogen solubility limit in zirconium must be taken into account to model hydrogen thermo-diffusion in zirconium alloys.

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Section: Matmentioning

confidence: 96%

Section: Matmentioning

confidence: 99%

Formation and characterization of hydride blisters in Zircaloy-4 cladding tubes

Ménibus

Auzoux

Dieye

et al. 2014

Journal of Nuclear Materials

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“…The behavior of high burnup fuel during a Reactivity Initiated Accident (RIA) has been studied experimentally in the NSRR [1,2] and CABRI reactors [3,4]. It is now well established that the accumulation of hydrides beneath the thick outer zirconia layer that can form in Zircaloy-4 claddings during base irradiation is a key factor with respect to fuel rod failure during the Pellet Cladding Mechanical Interaction (PCMI) phase of a RIA [5].…”

Section: Introductionmentioning

confidence: 99%

“…In the extreme case of a through-wall hydride blister, the failure can be brittle with no residual strains [6]. During simulated RIA transients on Zircaloy claddings, it has been reported that the rod failure proceeds in a mixed mode with a brittle fracture of the heavily hydrided periphery of the cladding and a ductile propagation in the remaining clad ligament [1][2][3][4]. Ductility is here associated to the change of direction of the throughwall crack, radially orientated in the hydride rim or blister and then bifurcating at ∼45°until the clad inner wall.…”

Section: Introductionmentioning

confidence: 99%

2D simulation of hydride blister cracking during a RIA transient with the fuel code ALCYONE

Sercombe

Helfer

Federici

et al. 2016

EPJ Nuclear Sci. Technol.

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Abstract. This paper presents 2D generalized plain strain simulations of the thermo-mechanical response of a pellet fragment and overlying cladding during a RIA transient. A fictitious hydride blister of increasing depth (25 to 90% of the clad thickness) is introduced at the beginning of the calculation. When a pre-determined hoop stress is exceeded at the clad outer surface, radial cracking of the blister is taken into account in the simulation by a modification of the mechanical boundary conditions. The hoop stress criterion is based on Finite Element simulations of laboratory hoop tensile tests performed on highly irradiated samples with a through-wall hydride blister. The response of the remaining clad ligament (beneath the cracked blister) to the pellet thermal expansion is then studied. The simulations show that plastic strains localize in a band orientated at ∼45°to the radial direction, starting from the blister crack tip and ending at the clad inner wall. This result is in good agreement with the ductile shear failures of the clad ligaments observed post-RIA transients. Based on a local plastic strain failure criterion in the shear band, ALCYONE simulations are then used to define the enthalpy at failure in function of the blister depth.

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“…Hydride blisters are local high hydrogen areas that could grow on Zircaloy-4 cladding external surface by a thermodiffusion mechanism. They induced a reduction in the cladding tube fracture resistance, in particular in the RIA PCMI phase (Fuketa et al [23]). …”

Section: Introductionmentioning

confidence: 99%

Fracture of Zircaloy-4 cladding tubes with or without hydride blisters in uniaxial to plane strain conditions with standard and optimized expansion due to compression tests

Ménibus¹,

Auzoux²,

Mongabure³

et al. 2014

Materials Science and Engineering: A

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test, which induces a near uniaxial loading, were proposed and developed to reach higher biaxiality ratios (ratio between mechanical quantities in axial and in circumferential direction). The first optimization, named HB-EDC for High-Biaxiality EDC, allowed to reach transverse plane strain conditions. The second optimization, named VHB-EDC for Very High Biaxiality EDC, was designed to reach higher loading biaxiality ratios. These optimized EDC tests were performed * Tel.: +33 1 69 08 39 43; e-mail: arthur.hellouin-de-menibus@cea.fr 1 at 25 • C, 350 • C and 480 • C on unirradiated hydrided Cold Worked Stress Relieved (CWSR) Zircaloy-4 samples. First, samples unhydrided or uniformly hydrided up to 1130 wppm were tested. Secondly, samples hydrided at 310 wppm with a hydride blister were tested. A large ductility reduction is induced by the increase in biaxiality level in absence of a hydride blister or with small blisters (<50 µm deep). The fracture strain decreases quickly with the blister depth at 25 • C, but more progressively at higher temperature. An equation that quantifies the fracture strain reduction with the blister depth is proposed. Eventually, one of the tests developed in the present study, the HB-EDC test, was proven to be a good compromise between the test complexity and the stress state reached. It is a good candidate to characterize the mechanical behaviour of irradiated cladding.

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Fuel failure and fission gas release in high burnup PWR fuels under RIA conditions

Cited by 64 publications

References 2 publications

Formation and characterization of hydride blisters in Zircaloy-4 cladding tubes

Formation and characterization of hydride blisters in Zircaloy-4 cladding tubes

2D simulation of hydride blister cracking during a RIA transient with the fuel code ALCYONE

Fracture of Zircaloy-4 cladding tubes with or without hydride blisters in uniaxial to plane strain conditions with standard and optimized expansion due to compression tests

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