skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A CFD M&S PROCESS FOR FAST REACTOR FUEL ASSEMBLIES

Abstract

A CFD modeling and simulation process for large-scale problems using an arbitrary fast reactor fuel assembly design was evaluated. Three dimensional flow distributions of sodium for several fast reactor fuel assembly pin spacing configurations were simulated on high performance computers using commercial CFD software. This research focused on 19-pin fuel assembly “benchmark” geometry, similar in design to the Advanced Burner Test Reactor, where each pin is separated by helical wire-wrap spacers. Several two-equation turbulence models including the k-e and SST (Menter) k-? were evaluated. Considerable effort was taken to resolve the momentum boundary layer, so as to eliminate the need for wall functions and reduce computational uncertainty. High performance computers were required to generate the hybrid meshes needed to predict secondary flows created by the wire-wrap spacers; computational meshes ranging from 65 to 85 million elements were common. A general validation methodology was followed, including mesh refinement and comparison of numerical results with empirical correlations. Predictions for velocity, temperature, and pressure distribution are shown. The uncertainty of numerical models, importance of high fidelity experimental data, and the challenges associated with simulating and validating large production-type problems are presented.

Authors:
;
Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
USDOE
OSTI Identifier:
941746
Report Number(s):
INL/CON-08-14131
TRN: US0807497
DOE Contract Number:
DE-AC07-99ID-13727
Resource Type:
Conference
Resource Relation:
Conference: XCFD4NRS (Experiments and CFD Code Applications to Nuclear Reactor Safety - OECD/NEA Workshop),Grenoble, France,09/10/2008,09/12/2008
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; BOUNDARY LAYERS; BURNERS; COMPUTERS; FAST REACTORS; FUEL ASSEMBLIES; GEOMETRY; REACTORS; SAFETY; SIMULATION; SODIUM; SPACERS; TEST REACTORS; TURBULENCE; VALIDATION; VELOCITY; Advanced Burner Test Reactor; CFD; Empirical Correlation; helical wire-wrap spacers; High Performance Computing; Large Scale Simulation; Production Code; Sensitivity Analysis; Sodium Cooled; three dimensional; turbulence models; Verification and Validation

Citation Formats

Kurt D. Hamman, and Ray A. Berry. A CFD M&S PROCESS FOR FAST REACTOR FUEL ASSEMBLIES. United States: N. p., 2008. Web.
Kurt D. Hamman, & Ray A. Berry. A CFD M&S PROCESS FOR FAST REACTOR FUEL ASSEMBLIES. United States.
Kurt D. Hamman, and Ray A. Berry. Mon . "A CFD M&S PROCESS FOR FAST REACTOR FUEL ASSEMBLIES". United States. doi:. https://www.osti.gov/servlets/purl/941746.
@article{osti_941746,
title = {A CFD M&S PROCESS FOR FAST REACTOR FUEL ASSEMBLIES},
author = {Kurt D. Hamman and Ray A. Berry},
abstractNote = {A CFD modeling and simulation process for large-scale problems using an arbitrary fast reactor fuel assembly design was evaluated. Three dimensional flow distributions of sodium for several fast reactor fuel assembly pin spacing configurations were simulated on high performance computers using commercial CFD software. This research focused on 19-pin fuel assembly “benchmark” geometry, similar in design to the Advanced Burner Test Reactor, where each pin is separated by helical wire-wrap spacers. Several two-equation turbulence models including the k-e and SST (Menter) k-? were evaluated. Considerable effort was taken to resolve the momentum boundary layer, so as to eliminate the need for wall functions and reduce computational uncertainty. High performance computers were required to generate the hybrid meshes needed to predict secondary flows created by the wire-wrap spacers; computational meshes ranging from 65 to 85 million elements were common. A general validation methodology was followed, including mesh refinement and comparison of numerical results with empirical correlations. Predictions for velocity, temperature, and pressure distribution are shown. The uncertainty of numerical models, importance of high fidelity experimental data, and the challenges associated with simulating and validating large production-type problems are presented.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2008},
month = {Mon Sep 01 00:00:00 EDT 2008}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • No abstract prepared.
  • A CFD modeling and simulation process for large-scale problems using an arbitrary fast reactor fuel assembly design was evaluated. Three-dimensional flow distributions of sodium for several fast reactor fuel assembly pin spacing configurations were simulated on high performance computers using commercial CFD software. This research focused on 19-pin fuel assembly “benchmark” geometry, similar in design to the Advanced Burner Test Reactor, where each pin is separated by helical wire-wrap spacers. Several two-equation turbulence models including the k–e and SST (Menter) k–? were evaluated. Considerable effort was taken to resolve the momentum boundary layer, so as to eliminate the need formore » wall functions and reduce computational uncertainty. High performance computers were required to generate the hybrid meshes needed to predict secondary flows created by the wire-wrap spacers; computational meshes ranging from 65 to 85 million elements were common. A general validation methodology was followed, including mesh refinement and comparison of numerical results with empirical correlations. Predictions for velocity, temperature, and pressure distribution are shown. The uncertainty of numerical models, importance of high fidelity experimental data, and the challenges associated with simulating and validating large production-type problems are presented.« less
  • Within the framework of Sodium Fast Reactor development, innovative fuel assembly cleaning operations are investigated to meet the GEN IV goals of safety and of process development. One of the challenges is to mitigate the Sodium Water Reaction currently used in these processes. The potential applications of aqueous solutions of mineral salts (including the possibility of using redox chemical reactions) to mitigate the Sodium Water Reaction are considered in a first part and a new experimental bench, dedicated to this study, is described. Anhydrous alternative options based on Na/CO{sub 2} interaction are also presented. Then, in a second part, amore » functional study conducted on the cleaning pit is proposed. Based on experimental feedback, some calculations are carried out to estimate the sodium inventory on the fuel elements, and physical methods like hot inert gas sweeping to reduce this inventory are also presented. Finally, the implementation of these innovative solutions in cleaning pits is studied in regard to the expected performances. (authors)« less
  • From the aspect of planning the power upgrading of nuclear reactors - including the VVER-440 type reactor - it is essential to get to know the flow field in the fuel assembly. For this purpose we have developed models of the fuel assembly of the VVER-440 reactor using the ANSYS CFX 10.0 CFD code. At first a 240 mm long part of a 60 degrees segment of the fuel pin bundle was modelled. Implementing this model a sensitivity study on the appropriate meshing was performed. Based on the development of the above described model, further models were developed: a 960more » mm long part of a 60-degree-segment and a full length part (2420 mm) of the fuel pin bundle segment. The calculations were run using constant coolant properties and several turbulence models. The impacts of choosing different turbulence models were investigated. The results of the above-mentioned investigations are presented in this paper. (authors)« less
  • A numerical investigation was performed to study the variation in axial velocity profiles occurring downstream of the inlet nozzle region of Nuclear PWR fuel assemblies. Computational Fluid Dynamic (CFD) models were prepared for the inlet nozzle region of a section of fuel assembly, simulating the lower support plate located under the fuel assembly, the inlet nozzle of the fuel and the downstream fuel region. Two different nozzle designs were modeled to study how each nozzle impacts the dissipation of the jet velocity profiles occurring downstream of the nozzle. The two different nozzle designs included a standard round chamfered hole flowmore » plate and a chamfered slotted flow plate. The evaluation of the axial velocity profiles occurring downstream of the nozzle flow plate is critical in understanding the fuel rod vibration and rod fretting in the first grid span. Excessive rod vibration in this region can occur due to high axial jet velocities and steep axial velocity gradients generated from the holes in the lower support plate. The excessive rod vibration can lead to fuel rod wear and fuel failure. Axial velocity profiles were predicted for the different nozzle designs using the CFX code. These velocity profiles were compared to air test velocity measurements for the same nozzle designs. Velocity measurements were made in a 3.763/1 over-scale air test section simulating a 6 x 6 rod array of the inlet nozzle region and downstream fuel region. Reasonable agreement was observed between the velocity measurements and CFD model predictions. The results also indicate that nozzle flow plate geometry can have a significant affect on the dissipation of the jet axial velocity profiles and the steepness of the axial velocity gradients downstream on the inlet nozzle. The application of CFD tools can be used to optimize the inlet nozzle geometry to better dissipate jets and reduce axial velocity gradients downstream of the nozzle at a minimal increase in pressure drop. This will help reduce fuel rod vibration and rod fretting. (authors)« less