THERMAL ACTIVATION METHOD FOR /rho/$sub 2$$sub 8$ MEASUREMENTS IN SLIGHTLY ENRICHED URANIUM OXIDE LATTICES

Abstract

This report describes the thermal activation method for measuring P28 in heterogeneous slightly enriched U02 lattices and gives resulls for 12 water-moderated lattices. The technique has three primary advantages over conventional U238 cadmium-ratio measurements: (1) uranium activities are measured by chemically processing the irradiated fuel to avoid problems associated with the use of U238 foils, (2) cadmium-covered uranium measurements are eliminated to avoid cadmium perturbations, and (3) P28 is obtained directly, rather than by subtracting one from the cadmium ratio, to avoid large errors when the cadmium ratio approaches unity. The technique compares total absorptions in U238 to thermal absorptions in an intermediate material, usually dysprosium, having a

Argonne Advanced Research Reactor Critical Experiments

“…As described in Ref. 18, the following relationship was used: that of a material y which has a larger cadmium ratio in the same medium F.…”

High Conversion Critical Experiments

“…G(T), where T is the foil thickness in absorption lengths, was obtainedzo from (23) where E3 is the exponential integral. The oxide pellets were corrected for thermal self-shielding by an escape-probability method.…”