Light water reactor fuel performance modeling and multi-dimensional simulation

Abstract

How would you……describe the overall significance of this paper? This paper describes the analytical modeling and simulation of light water reactor fuel behavior. This technology emphasizes highly detailed large-scale threedimensional computation and introduces to the traditional engineering-scale simulation the higher-order meso-scale and atomistic-scale modeling and simulation.…describe this work to a materials science and engineering professional with no experience in your technical specialty? The modeling of nuclear fuel systems involves complex physical phenomena that operate over time and geometric scales that vary by many orders of magnitude. These phenomena involve temporally and spatially dependent interactions between several material constituents that include ceramic UO 2 fuel, metallic cladding and two-phase water coolant, and take place under continuously changing irradiation and temperature conditions. The behavior of this system is simulated in multi-dimensional computer codes that constitute analytical analogs for the nuclear reactor core as a whole.…describe this work to a layperson? This paper describes the complex behavior of a nuclear reactor fuel system, which is composed of thousands of fuel rods, assembled in precise patterns and immersed in water in a pressure vessel. A typical fuel rod is a thin-walled metal tube, that contains several hundred uranium oxide pellets which generate heat through the nuclear fission process that takes place in a precisely controlled manner. The heat is transferred to the surrounding water in the vessel and is subsequently converted to mechanical energy and ultimately to electricity generation.Light water reactor fuel is a multicomponent system required to produce thermal energy through the fission process, efficiently transfer the thermal energy to the coolant system, and provide a barrier to fission product release by maintaining structural integrity. The operating conditions within a reactor induce complex multi-physics phenomena that occur over time scales ranging from less than a microsecond to years and act over distances ranging from inter-atomic spacing to meters. These conditions impose challenging and unique modeling, simulation, and verification data requirements in order to accurately determine the state of the fuel during its lifetime in the reactor. The capabilities and limitations of the current engineering-scale one-dimensional and two-dimensional fuel performance codes is discussed and the challenges of employing higher level fidelity atomistic modeling techniques such as molecular dynamics and phase-field simulations is presented.

Mechanistic materials modeling for nuclear fuel performance

“…The FALCON code, which has been available for nearly two decades, uses a finite element method (FEM) approach and is applicable to either 2D axisymmetric or planar geometries [6]. More recently, BISON, another FEM based fuel performance code, has been developed which employs parallel computation and can be applied to large, complex prob- Taken from Rashid et al [16] and adapted from Beyer et al [17] and Lassmann [8].…”

Investigation of thermal transport in composites and ion beam irradiated materials for nuclear energy applications

“…This applies to conditions where the exact temperature distribution is critical or where one is tasked with development and validation of model with predictive capability. 8,17,18 The latter typically involves the ability to predict thermal conductivity as a function of radiation induced microstructure. 19 Another limitation of both techniques is their lack of sensitivity to a thin damage layer resulting from ion beam irradiations, which is an alternative method used to simulate displacement damage caused by energetic neutrons and fission products.…”

“…17 Unlike current fuel performance codes which are essentially empirical models that are based on a limited set of experimental data, first principles based codes are expected to have predictive capability. This predictive capability of fuel performance codes is very important for understanding the fuel behavior under conditions beyond normal operation.…”

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

“…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. Having identified the PCI susceptible fuel rods from the core-wide analysis, axial segments of the susceptible fuel rods are subsequently analyzed utilizing a three-dimensional (r,z, BISON-CASL model, differing from current industry practice [17] in both incorporating a fuel performance model in the core-wide analysis and utilizing a threedimensional fuel performance model in the detailed analysis.…”