Examples of LEU Conversion Analyses in the RERTR Program

CONVERSION FEASIBILITY STUDIES FOR THE
GRENOBLE HIGH FLUX REACTOR

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

ABSTRACT

Feasibility studies for conversion of the High Flux Reactor (RHF) at Grenoble France have been performed at the Argonne National Laboratory in cooperation with the Institut Laue-Langevin (ILL). The uranium densities required for conversion of the RHF to reduced enrichment fuels were computed to be 7.9 g/cm3 with 20% enrichment, 4.8 g/cm3 with 29% enrichment, and 2.8 g/cm3 with 45% enrichment. Thermal flux reductions at the peak in the heavy water reflector were computed to be 3% with 45% enriched fuel and 7% with 20% enriched fuel. In each case, the reactor's 44 day cycle length was preserved and no changes were made in the fuel element geometry. If the cladding thickness could be reduced from 0.38 mm to 0.30 mm, the required uranium density with 20% enrichment would be about 6.0 g/cm3 and the thermal flux reduction at the peak in the heavy water reflector would be about 7%.

Significantly higher uranium densities are required in the RHF than in heavy water reactors with more conventional designs because the neutron spectrum is much harder in the RHF. Reduced enrichment fuels with the uranium densities required for use in the RHF are either not available or are not licensable at the present time.

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