Dilts, Gary A. | Engineering Papers

DOE OSTI2015

A parallel multi-domain solution methodology applied to nonlinear thermal transport problems in nuclear fuel pins

This paper describes an efficient and nonlinearly consistent parallel solution methodology for solving coupled nonlinear thermal transport problems that occur in nuclear reactor applications over hundreds of individual 3D physical subdomains. Efficiency is obtained by leveraging knowledge of the physical domains, the physics on individual domains, and the couplings between them for preconditioning within a Jacobian Free Newton Krylov method. Details of the computational infrastructure that enabled this work, namely the open source Advanced Multi-Physics (AMP) package developed by the authors is described. Details of verification and validation experiments, and parallel performance analysis in weak and strong scaling studies demonstrating the achieved efficiency of the algorithm are presented. Furthermore, numerical experiments demonstrate that the preconditioner developed is independent of the number of fuel subdomains in a fuel rod, which is particularly important when simulating different types of fuel rods. Finally, we demonstrate the power of the coupling methodology by considering problems with couplings between surface and volume physics and coupling of nonlinear thermal transport in fuel rods to an external radiation transport code.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2014

A Parallel Multi-Domain Solution Methodology Applied to Nonlinear Thermal Transport Problems in Nuclear Fuel Pins

This paper describes an efficient and nonlinearly consistent parallel solution methodology for solving coupled nonlinear thermal transport problems that occur in nuclear reactor applications over hundreds of individual 3D physical subdomains. Efficiency is obtained by leveraging knowledge of the physical domains, the physics on individual domains, and the couplings between them for preconditioning within a Jacobian Free Newton Krylov method. Details of the computational infrastructure that enabled this work, namely the open source Advanced Multi-Physics (AMP) package developed by the authors is described. Details of verification and validation experiments, and parallel performance analysis in weak and strong scaling studies demonstrating the achieved efficiency of the algorithm are presented. Furthermore, numerical experiments demonstrate that the preconditioner developed is independent of the number of fuel subdomains in a fuel rod, which is particularly important when simulating different types of fuel rods. Finally, we demonstrate the power of the coupling methodology by considering problems with couplings between surface and volume physics and coupling of nonlinear thermal transport in fuel rods to an external radiation transport code.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2012

Multispecies Diffusion Capability For The AMP Nuclear Fuel Performance Code (LANL Milestone M31MS060301 Final Report)

This work addresses only diffusion. The contact solver in AMP was not sufficiently developed this year to attempt treatment of species contact. A cylindrical tensor diffusion coefficient model was added to the AMP code, with the KHHS model [1] implemented into the AMP material library as a specific example. A cylindrical tensor diffusion operator manufactured solution verification example was coded. Before meeting the full text of the milestone task, it remains to: (1) code and run a cylindrical tensor diffusion solver manufactured solution (2) code and run the validation example of [1] (3) document results. These are dependent on developing new capabilities for the AMP code requiring close collaboration with the AMP team at ORNL. The model implemented provides a good intermediate first step toward a general multi-species solver. The multi-species capability of the AMP nuclear fuel code [2] is intended to allow the modeling of radiation-driven redistribution of various elements through solid metal nuclear reactor fuels. The initial model AMP provides for U-Pu-Zr fuels is based on the analysis of the Integral Fast Reactor (IFR) fuel development program experiment X419 post-irradiation data described in [1], referred to here as the KHHS model. This model may be specific to that experiment, but it was thought to provide a good start for the AMP code, because it (1) is formulated at the engineering scale, (2) decouples the species from each other, (3) predetermines the phase boundaries so that reference to a phase diagram is not needed, and (4) one of the authors (Hayes) was the NEAMS Fuels IPSC manager for FY11. The KHHS model is formulated for radial fluxes as little axial redistribution is seen experimentally. As U-Pu-Zr fuel is irradiated, the constituents migrate to form three annular regions. The center region is Zr-enriched and U-depleted, the middle region is Zr-depleted and U-enriched, and the outer region is Zr-enriched and U-depleted. The Pu concentration stays roughly constant throughout with slight enrichment in the center and depletion near the surface. Pu acts as a solvent for the mixture. The experiment was only run to 1.9% burnup, so the model is not at this time applicable to the high-burnup scenarios that the AMP code is intended to eventually model.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2011

Fiscal Year 2011 Infrastructure Refactorizations in AMP

In Fiscal Year 2011 (FY11), the AMP (Advanced MultiPhysics) Nuclear Fuel Performance code went through a thorough review and refactorization based on the lessons-learned from the previous year, in which the version 0.9 of the software was released as a prototype. This report describes the refactorization work that has occurred or is in progress during FY11.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2011

Vision Document for the AMP Nuclear Fuel Performance Code

The Advanced Modeling and Simulation Office (AMSO) with the United States (U.S.) Department of Energy (DOE) Office of Nuclear Energy (DOE/NE) oversees the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program and the Consortium for Advanced LWR Simulation (CASL), an Energy Innovation Hub. NEAMS is a program to develop advanced modeling and simulation capabilities for state-of-the-art and next generation nuclear energy applications and is composed of four Integrated Performance and Safety Code (IPSC) elements and four Cross-Cutting elements. The vision for the Fuels IPSC is to deliver an assessed (verified and validated) simulation capability to the fuel design and research community that is capable of predicting the behavior of nuclear fuel, cladding, and structural materials during nominal operation and anticipated operational transients that are beyond the well validated empirical basis that has historically required many integral experiments and operational experience for even moderate changes to fuel designs. Within the Fuels IPSC, the AMP(Advanced MultiPhysics) Nuclear Fuel Performance code (AMP) is targeted for the design and evaluation of Integral Effects Experiments, prediction and evaluation of in-reactor operation, and sensitivity/uncertainty evaluations that will be used to guide the development of lower-length-scale (LLS) research. There is also substantial work in progress to understand the lower-length-scale physics (grain-scale and below) of nuclear fuel, cladding, and structural materials within the Fuels IPSC, as well as the Fundamental Methods and Models (FMM) Cross-Cutting program element.

Clarno, Kevin T.↗