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Title: Advanced Multiphysics Thermal-Hydraulics Models for the High Flux Isotope Reactor

Engineering design studies to determine the feasibility of converting the High Flux Isotope Reactor (HFIR) from using highly enriched uranium (HEU) to low-enriched uranium (LEU) fuel are ongoing at Oak Ridge National Laboratory (ORNL). This work is part of an effort sponsored by the US Department of Energy (DOE) Reactor Conversion Program. HFIR is a very high flux pressurized light-water-cooled and moderated flux-trap type research reactor. HFIR s current missions are to support neutron scattering experiments, isotope production, and materials irradiation, including neutron activation analysis. Advanced three-dimensional multiphysics models of HFIR fuel were developed in COMSOL software for safety basis (worst case) operating conditions. Several types of physics including multilayer heat conduction, conjugate heat transfer, turbulent flows (RANS model) and structural mechanics were combined and solved for HFIR s inner and outer fuel elements. Alternate design features of the new LEU fuel were evaluated using these multiphysics models. This work led to a new, preliminary reference LEU design that combines a permanent absorber in the lower unfueled region of all of the fuel plates, a burnable absorber in the inner element side plates, and a relocated and reshaped (but still radially contoured) fuel zone. Preliminary results of estimated thermal safetymore » margins are presented. Fuel design studies and model enhancement continue.« less
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  1. ORNL
Publication Date:
OSTI Identifier:
DOE Contract Number:
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Resource Relation:
Conference: The 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16), Chicago, IL, USA, 20150830, 20150904
Research Org:
Oak Ridge National Laboratory (ORNL); High Flux Isotope Reactor (HFIR)
Sponsoring Org:
NNSA USDOE - National Nuclear Security Administration (NNSA)
Country of Publication:
United States
HFIR; LEU; Conversion; COMSOL; Multi-Physics; Heat Transfer; Turbulent Flow