Modeling the influence of interaction layer formation on thermal conductivity of U–Mo dispersion fuel

Abstract

The Global Threat Reduction Initiative Program continues to develop existing and new test reactor fuels to achieve the maximum attainable uranium loadings to support the conversion of a number of the world's remaining high-enriched uranium fueled reactors to low-enriched uranium fuel. Currently, the program is focused on assisting with the development and qualification of a fuel design that consists of a uranium-molybdenum (U-Mo) alloy dispersed in an aluminum matrix. Thermal conductivity is an important consideration in determining the operational temperature of the fuel and can be influenced by interaction layer formation between the dispersed phase and matrix, porosity that forms during fabrication of the fuel plates or rods, and upon the concentration of the dispersed phase within the matrix. This paper develops and validates a simple model to study the influence of interaction layer formation, dispersed particle size, and volume fraction of dispersed phase in the matrix on the effective conductivity of the composite. The model shows excellent agreement with results previously presented in the literature. In particular, the thermal conductivity of the interaction layer does not appear to be as important in determining the effective conductivity of the composite, while formation of the interaction layer and subsequent consumption of the matrix reveals a rather significant effect. The effective thermal conductivity of the composite can be influenced by the dispersed particle distribution by minimizing interaction layer formation and preserving the higher thermal conductivity matrix.

Effects of porous fuel structure on the irradiation-induced thermo-mechanical coupling behavior in monolithic fuel plates

“…. 因此, 研究试验堆燃料低浓化计划(The Reduced Enrichment for Research and Test Reactors, RERTR)提 出将高富集度铀燃料替换为低富集度铀燃料(LEU) [1][2][3] 的要求. 为了保证研究试验堆的高中子注量率, 需要提 高燃料的铀密度 [3] .…”

A model to predict thermal conductivity of irradiated U–Mo dispersion fuel

“…The interaction layer must consume the fuel, the matrix, or a mixture of both. Initial validation of the model using unirradiated U-Mo dispersion fuel (i.e., as-fabricated) measurements revealed that the best results were obtained when it was assumed that the interaction layer consumed only the matrix [8]. Based on those results, the same assumption was applied in the current model.…”

“…As a result, the thermal conductivity of the IL is often assigned a value lower than that of the dispersed fuel particle itself, with assumptions as low as 5.5 Wm -1 K -1 [7] being used. Previously, the authors developed a simple model to predict the thermal conductivity of dispersion type fuel and investigated the sensitivity of this property to parameters such as volume fraction (loading), particle size, and IL thickness [8]. The model was compared to measurements performed on unirradiated U-Mo dispersion fuel samples.…”

Atomistic simulations of the small xenon bubble behavior in U–Mo alloy

“…Until to now, lots of different uranium alloys have been tested and the U-Mo alloy has been identified as a high performance fuel due to the high uranium density and the low neutron capture cross-section of Mo [2][3][4][5][6].…”

“…The presence of Xe bubbles in U-Mo alloy fuel can drastically change its mechanical properties and thermophysical properties, especially lead to an important swelling, which can have dramatic consequences for the safety of nuclear devices. This is the reason why lots of theoretical and experimental studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] have been undertaken to understand the behavior of this U-Mo alloy fuel under irradiation, especially the effect of fission gas bubbles on the fuel properties. However, the behavior of small Xe bubbles, especially the basic processes governing its migration, coalescence and the release of Xe atoms from the U-Mo alloy fuel, has not been understood clearly.…”