Analysis of small-sample reactivity worths in the Fast Test Reactor Engineering Mockup Critical

Small-sample reactivity worths were computed and compared with measurements at core center and along a radial traverse of the Fast Test Reactor Engineering Mockup Critical (FTR-EMC). The computed worths were obtained with first order perturbation theory using real and adjoint neutron fluxes from 42-group X-Y diffusion theory calculations. The perturbation denominator (importance-weighted neutron production rate) was obtained from three-dimensional X-Y-Z calculations. For most of the calculated worths, cross sections were from the FTR Set 300S library (essentially ENDF/B version III data); however, ENDF/B version IV delayed neutron parameters were used to generate the necessary conversion factor to allow comparison of measured and calculated worths. At core center the C/E values were 1.14 to 1.33 for plutonium samples, 1.11 for a depleted uranium sample, 0.97 to 1.05 for boron, 0.89 to 1.08 for europia, 1.4 for stainless steel and 2.6 for iron oxide