North American Member News May 2021


Member News


15 June 2021


Eileen Supko

Transportation Packages for High-Assay Low-Enriched Uranium

ORNL Report
In February, the U.S. Nuclear Regulatory Commission released a report by its contractor, Oak Ridge National Laboratory (ORNL), on an assessment of existing transportation packages for use with high-assay low-enriched uranium (HALEU).

The truck transporting the UF6 was involved in a crash with another vehicle. The ORNL report, Assessment of Existing Transportation Packages for Use with HALEU, assesses the potential to use currently licensed transportation packages for the transportation of increased enrichment unirradiated uranium fuel forms. The assessment uses selected package designs that represent the five categories of fuel form and focuses on demonstrating subcriticality and identifying benchmark critical experiments for use in criticality code validation. The five fuel form categories include:

  • boiling water reactor (BWR) fuel rods and assemblies,
  • pressurized water reactor (BWR) rods and assemblies,
  • Uranium hexafluoride (UF6)
  • Uranium metal
  • Tri-structural isotropic (TRISO) particles
  • Uranium dioxide (UO2) pellets or powder

For each fuel form category, a representative package was evaluated. Results provided for each package evaluation include enrichment and packaging limits (e.g., maximum transportation array size as a function of enrichment) and benchmark critical experiment similarity coefficients. Results indicate that there are viable means for increasing enrichments into the HALEU range across the spectrum of fuel forms with differing increase amounts available for different packages. Sources of subcriticality margin to offset increased enrichment reactivity include reduced transportation array size, reduced fissile mass, burnable absorber credit, and safety analysis margin harvesting. For all packages except the DN-30, numerous critical benchmark experiment candidates for validation were identified.

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