Use of multiscale zirconium alloy deformation models in nuclear fuel behavior analysis

Abstract

Accurate prediction of cladding mechanical behavior is a key aspect of modeling nuclear fuel behavior, especially for conditions of pellet-cladding interaction (PCI), reactivity-initiated accidents (RIA), and loss of coolant accidents (LOCA). Current approaches to fuel performance modeling rely on empirical constitutive models for cladding creep, growth and plastic deformation, which are limited to the materials and conditions for which the models were developed. To improve upon this approach, a microstructurally-based zirconium alloy mechanical deformation analysis capability is being developed within the United States Department of Energy Consortium for Advanced Simulation of Light Water Reactors (CASL). Specifically, the viscoplastic self-consistent (VPSC) polycrystal plasticity modeling approach, developed by Lebensohn and Tomé [1], has been coupled with the BISON engineering scale fuel performance code to represent the mechanistic material processes controlling the deformation behavior of light water reactor (LWR) cladding. A critical component of VPSC is the representation of the crystallographic nature (defect and dislocation movement) and orientation of the grains within the matrix material and the ability to account for the role of texture on deformation. A future goal is for VPSC to obtain information on reaction rate kinetics from atomistic calculations to inform the defect and dislocation behavior models described in VPSC. The multiscale modeling of cladding deformation mechanisms allowed by VPSC far exceed the functionality of typical semi-empirical constitutive models employed in nuclear fuel behavior codes to model irradiation growth and creep, thermal creep, or plasticity. This paper describes the implementation of an interface between VPSC and BISON and provides initial results utilizing the coupled functionality.

Polycrystalline Simulations of In-Reactor Deformation of Zircaloy-4 Cladding Tubes during Nominal Operating Conditions

“…Following a similar approach as the one developed by Montgomery et al 15 and Patra and Tomé 16 , the polycrystalline model has been coupled to the pipe module of the MTest solver delivered with the opensource software MFront. This module allows the simulation of a 1D finite element calculation on pipes using the axisymmetrical generalized plain strain hypothesis classically used in mono-dimensional fuel performance codes 44 .…”

“…During the past several years, a renewed interest in the modelling of in-reactor deformation of zirconium alloys has arisen with the development of multiscale approaches from the single crystal to the structure component that couples a viscoplastic self-consistent model with a finite element code 15,16 . Recently, full-field simulations, based on the Fast Fourier Transform method, have also been applied to the in-reactor behavior of recrystallized Zircaloy-4 guide tubes 17 .…”

Modeling and simulation challenges pursued by the Consortium for Advanced Simulation of Light Water Reactors (CASL)

“…molecular dynamics) and mesoscale models (e.g. viscoplastic self-consistent model [15]). For core-wide analysis using VERA-CS coupled to BISON-CASL, referred to as TIAMAT [16], a two-dimensional (r,z) fuel performance model is employed to reduce computational burden.…”

Polycrystalline simulations of in-reactor deformation of recrystallized Zircaloy-4 tubes: Fast Fourier Transform computations and mean-field self-consistent model

“…Because of their industrial relevance and their significant plastic anisotropy, zirconium alloys have been an important topic of interest since the seminal work of Woo (Woo, 1985). This early paper was then followed by a large body of articles treating of deformation under irradiation of zirconium alloys, and especially irradiation creep and growth (Causey et al, 1988;Lebensohn and Tomé, 1993;Turner and Tomé, 1993;Tomé et al, 1993;Turner et al, 1994;Tomé et al, 1996;Turner et al, 1999;Tomé and Christodoulou, 2000;Patra et al, 2017;Montgomery et al, 2017).…”

“…These numerical approaches are based on solving rate theory equations (Barashev et al, 2015) or cluster dynamics modeling (Christien and Barbu, 2009). Recently, several authors (Montgomery et al, 2017;Patra et al, 2017) have introduced these rate theory equations into a self-consistent model to deduce the growth strain at the polycrystalline scale and not only at the grain scale.The macroscopic strain, averaged over the polycrystal, along the Z-axis is thus given by Eq. B-5, since the volume fraction of crystallographic phases is normalized to one.…”