HIGH BURNUP CHANGES IN UO<sub>2</sub>FUELS IRRADIATED UP TO 83 GWD/T IN M5<sup>(R)</sup>CLADDINGS

Noirot, J.; Aubrun, I.; Desgranges, Lionel; Hanifi, K.; Lamontagne, J.; Pasquet, B.; Valot, C.; Blanpain, P.; Cognon, H.

doi:10.5516/net.2009.41.2.155

Cited by 33 publications

(13 citation statements)

References 5 publications

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“…When the concentration of gas in the pores is deduced from the difference in the concentrations of retained Xe measured by LA-ICP-MS and EPMA the gas pressure in the pores is found to vary between 57 and 127 MPa (see Table 5). These values, however, could be too low based on current understanding that little fission gas release occurs from the HBS during normal reactor operation (see e.g., results from more recent investigations using SIMS [36,37] and an NFIR (Nuclear Fuel Industry Research) irradiation [38]). This Table 5 Average pressure of fission gas in the pores of the high burn-up structure at several radial positions in the outer region of the fuel in sample 12G2-GC.…”

Section: Gas Pressure In the Pores Of The High Burn-up Structurementioning

confidence: 95%

On the condition of UO2 nuclear fuel irradiated in a PWR to a burn-up in excess of 110 MWd/kgHM

Restani

Horvath

Goll

et al. 2016

Journal of Nuclear Materials

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Section: Gas Pressure In the Pores Of The High Burn-up Structurementioning

confidence: 95%

On the condition of UO2 nuclear fuel irradiated in a PWR to a burn-up in excess of 110 MWd/kgHM

Restani

Horvath

Goll

et al. 2016

Journal of Nuclear Materials

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“…Other parameters have been shown to have an influence on the HBS initiation threshold, such as the irradiation density rate, the fuel composition with an effect of the Pu presence, but also of the Gd concentration in poisoned fuels, some of the studied additives, like Cr, and, maybe some of the impurities. However, not all the differences in the UO 2 HBS rim extent measured by different teams on various fuels have been explained [2][3]. The effect of impurities may be the main reason for these differences, but it has not been documented enough yet.…”

Section: Fig 1: Sharp Limit Between Hbs and Non-hbs Areas In A 55 Gwmentioning

confidence: 97%

“…An increase of the fission gas release and an increase in the fuel swelling rate are measured [3]. It was shown by indirect and direct approaches that HBS formation was not the main contributor to the increase of fission gas release at high burn-up [1,[5][6].…”

Section: Fig 1: Sharp Limit Between Hbs and Non-hbs Areas In A 55 Gwmentioning

confidence: 99%

High Burn-up Structure in Nuclear Fuel: Impact on Fuel Behavior

Noirot

Pontillon

Lamontagne

et al. 2016

EPJ Web of Conferences

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When UO 2 and (U,Pu)O 2 fuels locally reach high burn-up, a major change in the microstructure takes place. The initial grains are replaced by thousands of much smaller grains, fission gases form micrometric bubbles and metallic fission products form precipitates. This occurs typically at the rim of the pellets and in heterogeneous MOX fuel Pu rich agglomerates. The high burn-up at the rim of the pellets is due to a high capture of epithermal neutrons by 238 U leading locally to a higher concentration of fissile Pu than in the rest of the pellet. In the heterogeneous MOX fuels, this rim effect is also active, but most of the high burn-up structure (HBS) formation is linked to the high local concentration of fissile Pu in the Pu agglomerates. This Pu distribution leads to sharp borders between HBS and non-HBS areas ( Fig.1). Fig. 1: Sharp limit between HBS and non-HBS areas in a 55 GWd/t HM MOX MIMAS fuel (from [1]).In these MOX fuels, the HBS forming at various radial positions, and not only at the rim, it was shown that the size of the new grains, of the bubbles and of the precipitates increase with the irradiation local temperatures. Other parameters have been shown to have an influence on the HBS initiation threshold, such as the irradiation density rate, the fuel composition with an effect of the Pu presence, but also of the Gd concentration in poisoned fuels, some of the studied additives, like Cr, and, maybe some of the impurities. However, not all the differences in the UO 2 HBS rim extent measured by different teams on various fuels have been explained [2][3]. The effect of impurities may be the main reason for these differences, but it has not been documented enough yet. It has been shown recently, with examinations of a UO 2 fuel in which 235 U was heterogeneously distributed, that a high Pu concentration is not mandatory for HBS formation [4].Several changes in the fuel behavior occur concomitantly with the HBS formation. An increase of the fission gas release and an increase in the fuel swelling rate are measured [3]. It was shown by indirect and direct approaches that HBS formation was not the main contributor to the increase of fission gas release at high burn-up [1,[5][6]. Indeed, studying the Kr/Xe ratio or some isotopic ratio in the gases collected during rod puncturing and using the differences in the gas productions as a function of the radial position, it was shown that the HBS areas were not the main source of the released gases. SIMS measurements of the local retention confirmed this trend. Nonetheless, the formation of a strong bonding between the fuel pellet periphery and the inner surface of the cladding, with the formation of the inner zirconia layer induces tensile stresses in the fuel during power

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“…It is known, for example, that UO 2 fuel undergoes a significant restructuring during reactor operation. [31][32][33][34] The main feature of this process is the formation of various texture zones in the fuel, as well as a complex distribution of bubble sizes and densities. The variation in texture and bubble type and density occurs mainly along the radial direction of the fuel pellet.…”

Section: Thermal Transport: Microstructure Scalementioning

confidence: 99%

Thermal conductivity of UO2 fuel: Predicting fuel performance from simulation

Phillpot

El–Azab²,

Chernatynskiy

et al. 2011

JOM

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How would you……describe the overall significance of this paper? Atomistic level simulations have not traditionally contributed to nuclear fuel performance simulations. However, recent advances in methodologies and computer power are now enabling atomic level simulations to provide mechanistic insights and parameters that can help in the development of performance codes.…describe this work to a materials science and engineering professional with no experience in your technical specialty? Predicting the thermal and mechanical properties of nuclear fuel is a difficult task due to the many length and time scales involved. In this paper we discuss how the results obtained at the atomistic scale contribute to the continuum models of the standard nuclear fuel performance codes.…describe this work to a layperson? Nuclear reactor performance depends crucially on the ability of the nuclear fuel to transport energy generated by the nuclear reaction to the electricity generating station. This ability is influenced greatly by the structure of the fuel at the very fine scale: down to the position of the individual atoms. In this paper we discuss how computer simulations are able to penetrate to this scale and help to predict energy transport characteristics of the nuclear fuel.Recent progress in understanding the thermal-transport properties of UO 2 for fission reactors is reviewed from the perspective of computer simulations. A path to incorporating more accurate materials models into fuel performance codes is outlined. In particular, it is argued that a judiciously integrated program of atomic-level simulations and mesoscale simulations offers the possibility of both better predicting the thermal-transport properties of UO 2 in light-water reactors and enabling the assessment of the thermal performances of novel fuel systems for which extensive experimental databases are not available.

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HIGH BURNUP CHANGES IN UO₂FUELS IRRADIATED UP TO 83 GWD/T IN M5^(R)CLADDINGS

Cited by 33 publications

References 5 publications

On the condition of UO2 nuclear fuel irradiated in a PWR to a burn-up in excess of 110 MWd/kgHM

On the condition of UO2 nuclear fuel irradiated in a PWR to a burn-up in excess of 110 MWd/kgHM

High Burn-up Structure in Nuclear Fuel: Impact on Fuel Behavior

Thermal conductivity of UO2 fuel: Predicting fuel performance from simulation

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HIGH BURNUP CHANGES IN UO2FUELS IRRADIATED UP TO 83 GWD/T IN M5(R)CLADDINGS

Cited by 33 publications

References 5 publications

On the condition of UO2 nuclear fuel irradiated in a PWR to a burn-up in excess of 110 MWd/kgHM

On the condition of UO2 nuclear fuel irradiated in a PWR to a burn-up in excess of 110 MWd/kgHM

High Burn-up Structure in Nuclear Fuel: Impact on Fuel Behavior

Thermal conductivity of UO2 fuel: Predicting fuel performance from simulation

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HIGH BURNUP CHANGES IN UO₂FUELS IRRADIATED UP TO 83 GWD/T IN M5^(R)CLADDINGS