Fission products and nuclear fuel behaviour under severe accident conditions part 3: Speciation of fission products in the VERDON-1 sample

Gall, Claire Le; Geiger, E.; Gallais-During, A.; Pontillon, Yves; Lamontagne, J.; Hanus, E.; Ducros, G.

doi:10.1016/j.jnucmat.2017.08.001

Cited by 13 publications

(5 citation statements)

References 18 publications

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“…The most reasonable hypothesis would be that molybdenum get oxidized in MoO 3 inside grains and is released from grain boundaries and interconnected pores. This kind of mechanism was postulated by Kleykamp and Le Gall from sole-release data. The fact that we did not detect any Mo oxides in grain boundaries by Raman spectroscopy and found MoO 2 homogeneously distributed inside grains would corroborate this mechanism.…”

Section: Discussionmentioning

confidence: 99%

“…Many integral and semianalytical research programs, like PHEBUS, HEVA, VERCORS, or VERDON, − were conducted in order to quantify the effect of temperature and atmosphere on FP release from irradiated nuclear fuel in accidental conditions. Most of these tests consist of submitting an irradiated fuel from PWR to high temperatures in different atmospheres (oxidizing/reducing) and measuring the FP release fraction from the fuel.…”

Section: Introductionmentioning

confidence: 94%

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Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x

Sarrasin¹,

Gaillard²,

Panetier³

et al. 2019

Inorg. Chem.

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Molybdenum is an abundant element produced by fission in the nuclear fuel UO2 in a pressurized water reactor. Although its radiotoxicity is low, this element has a key role on the fuel oxidation and other fission products migration, in particular in the case of an accidental scenario. This study aims to characterize the behavior of molybdenum in uranium dioxide as a function of environmental conditions (oxygen partial pressure, high temperature, UO2 oxidation) typical of an accidental scenario. To do so, molybdenum was introduced in UO2 or UO2+x pellets by ion implantation, a technique that allows us to mimic the production of Mo in the nuclear fuel by fission. Then, thermal treatments at high temperature and different oxygen partial pressures were carried out. The mobility of Mo in UOX samples was followed by secondary ion mass spectrometry (SIMS), while the Mo chemical speciation was investigated by spectroscopic techniques (XANES, Raman). In parallel, ab initio calculations were performed showing the effect of interstitial oxygen atoms on the Mo incorporation sites in UO2. We show that the Mo mobility is directly connected to its chemical state, which in turn, is linked to the redox conditions. Indeed, under reducing atmosphere, Mo is present in UO2 or UO2+x samples under a metallic state Mo(0). Its mobility, being quite low, is driven by a diffusion mechanism. An increase of pO2 entails the UO2 and Mo oxidation and, as a consequence, a strong release of this element. We show an increase of the Mo release rate with the increase of the UO2+x hyper-stoichiometry x. After thermal treatment, Mo remaining in the samples is located in the grains under the MoO2 form. Our experimental results are assessed by ab initio calculations showing that in the presence of oxygen Mo atoms adopt in UO2 a local structure close to the octahedral local geometry of Mo oxides.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x

Sarrasin¹,

Gaillard²,

Panetier³

et al. 2019

Inorg. Chem.

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“…This phenomenon could explain the main burst release observed for Xe and Kr during the oxidation plateau. Indeed, as the pores interconnected, paths were created in the whole sample for gaseous FP to diffuse more rapidly in the sample and release from the fuel [13].…”

Section: Discussion On U-zr Interactionmentioning

confidence: 99%

“…Further characterizations of the VERDON-1 sample are presented in the third part of this article [13]. These analyses are focused on the evolution of FP inside the fuel during the VERDON-1 test.…”

Section: Indifferent Pointmentioning

confidence: 99%

Fission products and nuclear fuel behaviour under severe accident conditions part 2: Fuel behaviour in the VERDON-1 sample

Geiger

Gall

Gallais-During

et al. 2017

Journal of Nuclear Materials

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Within the frame of the International Source Term Program, VERDON program aims at quantifying the source term of radioactive materials in case of a hypothetical severe accident in a Light Water Reactor (LWR). Tests were performed in a new experimental laboratory (VERDON) built in the LECA-STAR facility (CEA Cadarache). The VERDON-1 test was devoted to the study of a high burn-up UO 2 fuel and FP release at very high temperature (≈ 2600°C) under reducing atmosphere. Post-test qualitative and quantitative characterizations of the VERDON-1 sample led to the proposal of a scenario explaining what might have occurred during the experimental sequence. Hence the fuel and the cladding might have interacted leading to the melt of UO 2-ZrO 2 system. Besides no relocation was observed during the test, it might have been imminent.

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“…Experimental programs have been launched worldwide to study and quantify FP release during SAs. Among them, separate-effect tests were performed at the CEA in 2 different programs: VERCORS [1][2][3] [4] and VERDON [5][6] [7]. These tests were launched to study the impact of several parameters on FP release: burnup of the fuel, geometry of the fuel fragments, oxidizing/reducing atmosphere, etc...…”

Section: Introductionmentioning

confidence: 99%

Modeling of fission product release during severe accidents with the fuel performance code ALCYONE

Germain

Sercombe

Riglet-Martial

et al. 2022

Nuclear Engineering and Design

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Fission products and nuclear fuel behaviour under severe accident conditions part 3: Speciation of fission products in the VERDON-1 sample

Cited by 13 publications

References 18 publications

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x

Fission products and nuclear fuel behaviour under severe accident conditions part 2: Fuel behaviour in the VERDON-1 sample

Modeling of fission product release during severe accidents with the fuel performance code ALCYONE

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Fission products and nuclear fuel behaviour under severe accident conditions part 3: Speciation of fission products in the VERDON-1 sample

Cited by 13 publications

References 18 publications

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO2 and UO2+x

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO2 and UO2+x

Fission products and nuclear fuel behaviour under severe accident conditions part 2: Fuel behaviour in the VERDON-1 sample

Modeling of fission product release during severe accidents with the fuel performance code ALCYONE

Contact Info

Product

Resources

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Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x