Uranium-238 Resonance Self-Indication Capture Measurements

Neutron self-indication measurements simulating ²³⁸U capture in reactors have been carried out over the energy range from 3 eV to 3 keV using shielding samples at 77, 293, and 873 K. The data have been reduced to open and self-shielded capture yields provided on magnetic tape as benchmark data for comparison with nuclear design calculations. The important energy range below 100 eV has been analyzed in detail both to obtain improved resonance parameters for the levels at 6.67, 20.9, 36.8, 66.1, and 80.7 eV and to examine the accuracy with which cross sections are calculated from resonance formalisms. The improved resonance parameters, when used with an accurate but practical multilevel formalism, reduce by about one-half the long-standing discrepancy between calculated and measured ²³⁸U resonance capture integrals.