Modeling porosity migration in LWR and fast reactor MOX fuel using the finite element method

JOURNAL OF NUCLEAR MATERIALS

卷:508

Article

Novascone, Stephen¹  Medvedev, Pavel¹  Peterson, John W.²  Zhang, Yongfeng¹  Hales, Jason¹ 

[1] Idaho Natl Lab, Fuels Modeling & Simulat, Idaho Falls, ID 83415 USA

[2] Idaho Natl Lab, Modeling & Simulat, Idaho Falls, ID 83415 USA

关键词: Nuclear fuel;    Porosity;    Fast mixed oxide;    Finite element method;   

DOI  :  10.1016/j.jnucmat.2018.05.041

来源: Elsevier

【 摘 要 】

An engineering-scale finite element simulation of pore migration in oxide fuel is presented. The porosity field is governed by an advection-diffusion equation which is coupled to the fuel temperature and stress fields through the thermal conductivity and volumetric heat source term. The engineering-scale porosity equation models the microscopic process of vapor transport of fuel across pores, taking into account thermal and vapor pressure gradients within the fuel. In the simulations, the porosity is initialized to a constant value at every point in the domain, and as the temperature gradient is increased by application of a heat source, the pores move up the thermal gradient and accumulate at the center of the fuel in a time frame that is consistent with experimental observations. Results from representative simulations are provided to demonstrate the new capability, and we show that a sufficiently high power ramp rate limits restructuring and leads to a corresponding increase in fuel temperature. We also discuss the finite element mesh density required to compute pore migration and present multidimensional results. (C) 2018 Elsevier B.V. All rights reserved.

【 授权许可】

Free