An Efficient High-to-Low Iterative Method for Light Water Reactor Analysis Based on NEAMS Tools
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Nuclear Science & Technology↗
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The NEAMS Integrated Computational Environment (NiCE)
Many new, high-performance nuclear energy modeling and simulation tools are under development in the United States and many more existing projects are moving to high-performance computing. This shift to state-of-the-art modeling and simulation will not only result in an unprecedented use of computing resources but it will generate extremely large amounts of data in extraordinary detail. Domain scientists will find themselves simultaneously in two positions: managing the complexity of their own problem domain and managing the complexity of a nightmarish scenario of high-performance computational tools. We believe that the computational science community should develop integrated tools for coupling, working with and analyzing data from simulation codes instead of leaving domains scientists and students to fend for themselves and come up with a working solution. While many projects offer some set of tools to work with their codes, to launch jobs remotely or to setup input files, most of these tools are rarely integrated in a holistic way to provide an easy, common and high-productivity environment for users. For that matter, most remote jobs are launched on the machine in the other room, but that certainly will not work for larger problems that require Leadership Class computing resources found only at U.S. National Laboratories or similar facilities. Overcoming the challenges of launching on these machines and even on public or private clouds are left as a challenge to the user.
Source record↗
NEAMS Update. Quarterly Report for April - June 2012
Quarterly Highlights: The interface of AMP was changed to prepare it for integration with Sharp; Bison was enhanced with improved models for cladding and coolant channels; FRAPCON and OECD-NEA databases are being used to evaluate Bison; The validation of Bison is being implemented with the recently developed discovery, accumulation, and assessment process; A study of microstructure and fission gas bubbles in UO2 f fuels showed how these characteristics affect fuel thermal conductivity; The thermal conductivity studies were informed by additional work on the kinetics of gas bubble evolution and cladding alloy properties, providing methods to express subcontinuum properties in continuum models; The new insights into the evolution of thermal conductivity in UO 2 fuels were used to drive mesoscale simulations with atomic-scale properties; The rapid development of Relap-7 continued, and initial modeling of a pressurized water reactor was successfully completed; Extension of Relap-7 to novel reactor concepts provided opportunities to refine the code; Risk grading of Relap-7 was completed; Simulations of the Advanced Test Reactor show that Proteus is ready to use; Simulations of an important pipe flow benchmark show that Nek5000 is also ready to use; Mesh generation for Sharp has advanced to unprecedented complexity, with the capability to create a mesh with up to 1,500,000 elements in an intricate configuration; A model for hydride reorientation in used fuel was demonstrated and implemented; Work continued on the use of molecular dynamics to simulate the crystalline properties of structural materials.
Bradley, Keith S..↗
NEAMS: The Nuclear Energy Advanced Modeling and Simulation Program [Poster]
Abstract not provided.
Bradley, K.↗
Technical Spotlight: NEAMS Structural Mechanics with Diablo
The Diablo code being developed at Lawrence Livermore National Laboratory (LLNL) uses implicit, Lagrangian finite element methods for the simulation of solid mechanics and multi-physics events over moderate to long time frames. A recent effort examined technologies needed to extend Diablo for use in seismic response incorporating soil-structure interaction (SSI). Our SSI study was intended to illustrate how advanced time-domain simulation approaches compare with and complement the standard frequency-domain approach for SSI.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NEAMS Software V&V Plan for the MARMOT Software
In order to ensure the accuracy and quality of the microstructure based materials models being developed in conjunction with MARMOT simulations, MARMOT must undergo exhaustive verification and validation. Only after this process can we confidently rely on the MARMOT code to predict the microstructure evolution within the fuel. Therefore, in this report we lay out a V&V plan for the MARMOT code, highlighting where existing data could be used and where new data is required.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NEAMS FPL M2 Milestone Report: Development of a UO₂ Grain Size Model using Multicale Modeling and Simulation
This report summarizes development work funded by the Nuclear Energy Advanced Modeling Simulation program's Fuels Product Line (FPL) to develop a mechanistic model for the average grain size in UO₂ fuel. The model is developed using a multiscale modeling and simulation approach involving atomistic simulations, as well as mesoscale simulations using INL's MARMOT code.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NEAMS Update. Quarterly Report for January - March 2014
This quarterly report covers the following points: A fully three-dimensional smeared cracking model has been implemented and tested in BISON; DAKOTA-BISON was used to study the parameters that govern heat transfer across the fuel-cladding; Calculations of grain boundary mobility in UO 2 have been extended to high temperatures; Mesh adaptivity is being employed in MARMOT simulations to increase computational efficiency; Molecular dynamics simulations have shown correlation between atomic displacements and the anisotropic thermal conductivity in UO 2 ; The SHARP team continues to address the application of the toolkit to assembly deformations driven by reactivity feedback; The Nek5000 team has extended the low-Machnumber capability to mixtures with multiple species; The generalized cross section library has been tested for various fuel assemblies and reactor types; and The subgroup cross-section interface was successfully implemented in PROTEUS-SN (page 6).
99 GENERAL AND MISCELLANEOUS↗
NEAMS-ATF M3 Milestone Report: Literature Review of Modeling of Radiation-Induced Swelling in Fe-Cr-Al Steels
Fe-Cr-Al steels are proposed as accident-tolerant-fuel (ATF) cladding materials in light water reactors due to their excellent oxidation resistance at high temperatures. Currently, the understanding of their performance in reactor environment is still limited. In this review, firstly we reviewed the experimental studies of Fe-Cr-Al based alloys with particular focus on the radiation effects in these alloys. Although limited data are available in literature, several previous and recent experimental studies have shown that Fe-Cr-Al based alloys have very good void swelling resistance at low and moderate irradiation doses but the growth of dislocation loops is very active. Overall, the behavior of radiation damage evolution is similar to that in Fe-Cr ferritic/martensitic alloys. Secondly, we reviewed the rate theory-based modeling methods for modeling the coevolution of voids and dislocation loops in materials under irradiation such as Frenkel pair three-dimensional diffusion model (FP3DM) and cluster dynamics. Finally, we summarized and discussed our review and proposed our future plans for modeling radiation damage in Fe-Cr-Al based alloys.
36 MATERIALS SCIENCE↗
NEAMS-IPL MOOSE Framework Activities
The Multiapp Picard iteration Milestone’s purpose was to support a framework level “tight-coupling” method within the hierarchical Multiapp’s execution scheme. This new solution scheme gives developers new choices for running multiphysics applications, particularly those with very strong nonlinear effects or those requiring coupling across disparate time or spatial scales. Figure 1 shows a typical Multiapp setup in MOOSE. Each node represents a separate simulation containing a separate equation system. MOOSE solves the equation system on each node in turn, in a user-controlled manner. Information can be aggregated or split and transferred from parent to child or child to parent as needed between solves. Performing a tightly coupled execution scheme using this method wasn’t possible in the original implementation. This is was due to the inability to back up to a previous state once a converged solution was accepted at a particular Multiapp level.
97 MATHEMATICS AND COMPUTING↗
NEAMS-IPL MOOSE Midyear Framework Activities
The MOOSE Framework is a modular pluggable framework for building complex simulations. The ability to add new objects with custom syntax is a core capability that makes MOOSE a powerful platform for coupling multiple applications together within a single environment. The creation of a new, more standardized JSON syntax output improves the external interfaces for generating graphical components or for validating input file syntax. The design of this interface and the requirements it satisfies are covered in this short report.
97 MATHEMATICS AND COMPUTING↗
NEAMS-IPL MOOSE Framework Activities 2017
The MOOSE Framework is a modular pluggable framework for building complex simulations. The ability to add new objects with custom syntax is a core capability that makes MOOSE a powerful platform for coupling multiple applications together within a single environment. The creation of a new, more standardized JSON syntax output improves the external interfaces for generating graphical components or for validating input file syntax automatically without the need for explicit developer interaction. The design of this interface and the requirements it satisfies are covered in this short report.
97 MATHEMATICS AND COMPUTING↗
NEAMS-IPL MOOSE Midyear Framework Activities
Multiphysics Object Oriented Simulation Environement (MOOSE) is a modular, pluggable framework for building complex simulations. The ability to add new objects with custom syntax is a core capability that makes MOOSE a powerful platform for coupling multiple applications together within a single environment. Documentation is not only a required component for a complete software quality assurance plan, but is critical to the overall success and wide-spread adoption of the platform by other researchers and institutions. Therefore, the notion of a modular, pluggable framework has been extended to the creation of documentation content. This report details the methodology for defining the NQA-1 compliant requirements in a manner that allows for the automatic generation of the Software Requirement Specification (SRS), Software Design Description (SDD), and Requirement Traceabiltity Matrix (RTM) from any repository revision.
97 MATHEMATICS AND COMPUTING↗
Nuclear Energy Advanced Modeling and Simulation (NEAMS) Accident Tolerant Fuels High Impact Problem: Engineering Scale Models and Analysis
As part of the Department of Energy's Nuclear Energy Advanced Modeling and Simulation program, an Accident Tolerant Fuel High Impact Problem was initiated at the beginning of fiscal year 2015 to investigate the behavior of \usi\ fuel and iron-chromium-aluminum (FeCrAl) cladding under normal operating and accident reactor conditions. The High Impact Problem was created in response to the United States Department of Energy's renewed interest in accident tolerant materials after the events that occurred at the Fukushima Daiichi Nuclear Power Plant in 2011. The High Impact Problem is a multinational laboratory and university collaborative research effort between Idaho National Laboratory, Los Alamos National Laboratory, Argonne National Laboratory, and the University of Tennessee, Knoxville. This report summarizes the latest recommended material models to be used for engineering scale simulations based upon lower length scale analyses described elsewhere. Comparative analyses between traditional fuel rods (U 3 Si 2 /Zircaloy-4) and the proposed accident tolerant fuel rods (UO 2 /FeCrAl and U 3 Si 2 /Zircaloy-4) under normal operation, loss of coolant, and reactivity insertion conditions have been revisited using the latest state-of-the-art models implemented into the Bison fuel performance code. Sensitivity analyses have also been redone to take into account the latest knowledge on uncertain parameters.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Bison Documentation Update, NEAMS Fuels Product Line Review Meeting
A brief overview of the status of the Bison documentation system is given. The Bison documentation system, which is built using the MOOSEDocs capability, has undergone significant development in the last two years to create a flexible, unified, and comprehensive documentation source for the Bison code. This documentation system, which is both hosted online (INL/MIS-18-50577) and can be built locally, integrates the older separate Bison user and theory manuals into a single format. The development of the documentation system, which is still ongoing, has three main objectives: improved step-by-step tutorial and workshop instructions for new users, implementation of detailed theory and input file information on a single page for each class, and increased accessibility of the documentation information. The progress and future work on these three objectives is reviewed.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Experimental and Computational Analysis of NEAMS Pebble Bed Reactors
The Advanced High-Temperature Pebble Bed Reactor concept leverages a particle-based fuel format consisting of discrete spherical graphite pebbles arrayed in a packed bed architecture. Thermal regulation achieved via flow of gas (e.g., helium) or liquid (e.g., molten salt) coolants through the void spaces between pebbles in the bed (characteristic pebble diameters: ~ 6 cm, gas cooled; ~ 3 cm, liquid cooled). This design is of interest owing to inherent advantages including passive safety features and highly efficient heat transfer characteristics that enable high power densities to be achieved. Fully leveraging these advantages requires a fundamental understanding of the complex coolant flow structure within the pebble-shaped fuel bed. Unfortunately, complexities associated with non-invasively probing the micro-scale flow phenomena within the complex network of void spaces between pebbles have hindered efforts to characterize the underlying transport phenomena. Without this fundamental foundation, it becomes challenging to rationally construct macroscopic transport models based upon volume averages of micro-scale parameters that accurately capture the observed flow behavior. Consequently, this lack of fundamental knowledge has limited previous work to coarse comparisons between theory and extremely limited experimental data. Moreover, these comparisons have been made only in terms of integral or macroscopic results. Therefore, multipoint measurements with a high level of spatial and temporal resolution are critically needed to fully map the complex flow patterns and to provide data at high spatial density to permit accurate volume averaging in the pebble bed. For this project, we performed a coordinated experimental and computational effort to quantitatively map the full-field velocity and temperature fields in the interstitial spaces within the pebble bed. The major accomplishments of this project included the important knowledge acquired for the flow mixing and heat transfer in the interstitial pore scales, the effects of flow mixing in the near-wall and far-wall regions, and the by-pass flows of pebble bed systems. The produced high-resolution experimental data (not broadly available in existing literature) were then used for the numerical studies enabling the refinement and validation of standard simulation tools (Nek5000).
42 ENGINEERING↗
Summary of Bison documentation and UX milestones - NEAMS FY20 Report
This summary report contains an overview of work performed under the work package entitled “MS- 20IN020107 - BISON advanced numerical model development and usability improvements - INL”, which is focused on the development and support of the fuel performance code BISON [1]. The second chapter lists FY20 milestones titles, completion schedule, and milestone level. Subsequent chapters summarize and demonstrate completion of milestones and activities. The last chapter outlines FY21 proposed future work.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NEAMS Workbench MOOSE Integration Update
Explore the source record for details and available documents.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗