As part of the RERTR Program whole-core demonstration in the Ford Nuclear Reactor (FNR) at the University of Michigan, data have been obtained which will allow more extensive validation of neutronics methods for whole-core calculations of an equilibrium high-enriched-uranium (HEU) core and a fresh low-enriched-uranium (LEU) core. A series of experiments designed to provide the data needed for these validations has been performed in the Pool Critical Assembly (PCA) at the Oak Ridge National laboratory (ORNL). This paper reports the results of the measurements and of the subsequent validation calculations performed at ANL. Measurements were made on approximately 20 different critical configurations in the PCA during the period June 15 to 26, 1981. The normal PCA fuel elements contained high-enriched uranium (HEU, 93 wt% 235U) while the reduced-enrichment fuel elements, obtained for irradiation testing in the Oak Ridge Research Reactor (ORR) under the fuel demonstration activity of the RERTR Program, contained either medium-enriched uranium (MEU, 45 wt% 235U) or low-enriched uranium (LEU, 19.8 wt% 235U).