Abstracts and Available Papers Presented at the
1997 International RERTR Meeting

A NEUTRONIC FEASIBILITY STUDY FOR LEU CONVERSION OF THE 
HIGH FLUX ISOTOPE REACTOR (HFIR)

S. C. Mo and J. E. Matos
Argonne National Laboratory
Argonne, Illinois 60439-4841 USA

ABSTRACT

A neutronic feasibility study was performed to determine the uranium densities that would be required to convert the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) from HEU (93%) to LEU (<20%) fuel. The LEU core that was studied is the same as the current HEU core with changes that include only fuel enrichment (19.75%), fuel type (U₃Si₂), burnable poison and fuel meat distribution (graded and uniform fuel plates). If the ratio of the inner fuel element to outer fuel element uranium density is preserved, the conversion of HFIR from HEU fuel to LEU fuel requires a uranium density of 6 to 7 gU/cm³ in the inner fuel element and 9 to 10 gU/cm³ in the outer fuel element to match the cycle length of the HEU core. Modifications in fuel grading and burnable poison distribution are needed to produce an acceptable power distribution.

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