A critical studies program for the Enrico Fermi Atomic Power Plant was run with the ZPR-III fast critical facility. The objectives of this program included determination of the U enrichment required for criticality, the effect of minor variations in core and blanket composition, reactivity coefficients, control and safety rod characteristics, power distribution, spectral indices, and the reactivity worth and wave shape of the oscillator rod. The experimental program was separated into two phases. The first phase involved investigatlona of a clean assembly, which was a simplified and homogenized core and blanket geometry constructed for ease of experimental manipulation and analysis. The second phase involved experiments on the engineered, or as-designed, core. This assembly included such engineering details as control and safety rod channels, core end gaps, and a precise reconstruction of the core outline. This provided detailed information on worths of control rods and fuel subassemblies, power distribution, and the effect of variations in core and end-gap dimensions. The application of critical experiment data to the determination of the Enrico Fermi reactor characteristics has established the U/sup 235/ enrichment for the fuel alloy, worths of fuel subassemblies, and the B/sup 10/ enrichment for the control and safety rods. In addition, material-substitution experiments and fuel-worth measurements have provided the parametric data for the determination of the net temperature coefficient of the Enrico Fermi reactor. (auth)
