Abstract
The Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR) is an 85 MWt flux trap-type research reactor that supports key research missions, including isotope production, materials irradiation, and neutron scattering. The core consists of an inner and an outer fuel element containing 171 and 369 involute-shaped plates, respectively. The thin fuel plates consist of a U3O8-Al dispersion fuel (highly enriched), an aluminum-based filler, and aluminum cladding. The fuel meat thickness is varied across the width of the involute plate to reduce thermal flux peaks at the radial edges of the fuel elements. Some deviation from the designed fuel meat shaping is allowed during manufacturing. A homogeneity scan of each fuel plate checks for potential anomalies in the fuel distribution by scanning the surface of the plate and comparing the attenuation of the beam to calibration standards. While typical HFIR simulations use homogenized fuel regions, explicit models of the plates were developed under the Low-Enriched Uranium Conversion Program. These explicit models typically include one inner and one outer fuel plate with nominal fuel distributions, and then the plates are duplicated to fill the space of the corresponding fuel element. Therefore, data extracted from these simulations are limited to azimuthally averaged quantities. To determine the reactivity and physics impacts of an as-built outer fuel element and generate azimuthally dependent data in the element, 369 unique fuel plate models were generated and positioned. This model generates the three-dimensional (i.e., radial–axial–azimuthal) plate power profile, where the azimuthal profile is impacted by features within the adjacent control element region and beryllium reflector. For an as-built model of the outer fuel element, plate-specific homogeneity data, 235U loading, enrichment, and channel thickness measurements were translated into the model, yielding a much more varied azimuthal power profile encompassed by uncertainty factors in analyses. These models were run with the ORNL-TN and Shift Monte Carlo tools, and they contained upwards of 500,000 cells and 100,000 unique tallies.
Highlights
The Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR) is a very high power density research reactor supporting several scientific missions, including neutron scattering, isotope production, and materials irradiation
Eng. 2021, 2, FOR PEER RpEVoIwEWersTwheercehnaneagrelyinbtohuenrdeaecdtivbiytythwoasseroelfatthiveelays-sdmeaiglln(e5d00mpocmde)la(nFdig, uasreex5p).ecLteodc,adliuzeedto6 impthaectusnodfeirnlcooardpinogra(trienlgattihvee taos-absu-diletsdigantaedsh) oofwfeudelrpeldautecsedtopweaarkdrtehleatriavdeiaploawnedradxeianlseitdiegses (Figouf rteh5e),palgaateins. dRueeptloictahtienugntdheerlaosa-ddiensgigantetdhefuraedl ipallaetdesgetshorof uthgehocourte.the outer fuel element (OFE) yielded a smooth, well-behaved plate power distribution that was impacted by the features in the control element and reflector regions (Figure 5): the plate power recovered in azimuthal locations adjacent to the four gaps between the absorbers within the control elements
The programmatic generation of the explicit fuel plate models developed under the LEU Conversion Program streamlined the generation of these models and incorporation
Summary
The Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR) is a very high power density research reactor supporting several scientific missions, including neutron scattering, isotope production, and materials irradiation. The water-cooled reactor consists of several concentric cylindrical regions (Figure 1), including a central flux trap, core, control elements, and beryllium reflectors. The core consists of a 171-plate inner fuel. The core consists of a 171-plate inner fuel elecmoenntrto(lIFeEle)maenndtsa, a3n69d-pbleartyelloiuumterrefufleelcteolersm. Of particular interest is the fission density and relative fission density distributions within the IFE and OFE fuel plates, which are typically azimuthally integrated quantities due to the transport model. This model explicitly defines one IFE and one OFE fuel plate and duplicates this plate throughout the IFE and OFE regions. The relative fission density Fd takes the fission density distribution and effectively renormalizes it over an overlaid mesh to account for the volumetric distribution of the fuel,
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
