General research and development on water-cooled and sodium-cooled reactors are reported along with specific developments on EBWR, BORAK-V, EBR-I, and EBR-H. Thermal and fast reactor safety studies are summarized in terms of fuel-coolant chemical reactions, kinetics of oxidation and ignition of reactor materials, core meltdown studies, and a sodium vapor pressure furnace. Evaluations were made of improved fast reactors for central station power and of a 50-Mwe Prototype Organic Power Reactor (POPR). Developments in instruments, reactcr fuels and materials, reactor components, heat engineering, separations processes, and advanced reactcrs are discussed. (M.C.G.)

Design, development, and testing efforts were continued on BORAX-V, EBR- I, EBR-II, EBWR, JUGGERNAUT ZPRIII, ZPR-VI, and ZPR-W. An evaluation program is outlined for Pebble Bed Reactor designs. Fast and thermal reactor safety studies were conducted. Experimental and theoretical studies in applied nuclear and reactor physics are dsscribed. Developments made in reactor components, fuels, and materials are discussed. Heat engineering studies were conducted on steam separation, and velocity and void distributions in two-phase systems. Fluidization and fluoride volatility separation, and chemical-metallurgical separation processes were studied. Advanced reactor concepts that were discusssd includsed. Basic Radiation Effects Beactor, Biogeonuclear Reactor, Fast Reactor Test Facility, compact high-power density fast reactors, AHFR hydraulic test loop, Packed Bed Reactor, and direct conversion. (For preceding period see ANL- 6328.) (B.O.G.)

Modifications of EBWR are described, and data from analysis of control- rod operational crud deposit are tabulated. Development and construction progress on Borax V are summarized. Research for ZPR III is reported on a series of uranium oxide critical cores. Comparative data on composition, critical masses, and central fission ratios are tabulated for these assemblies. Developmental work on ZPR-VI, ZPR-IX, and Juggernaut is summarized, followed by a summary of EBR-I operation and development of EBR-II. Studies of reactor steam superheating concepts are reported from which conclusions are listed. In reactor safety studies, data were obtained on the extent of water reaction with various metal combinations for use in cores as function of energy input. In other work in-pile melt down studies were conducted. Operation and development of TREAT are described. Nuclear technological developments are summarized in sections on physics, fuel development, reactor components and materials, separations development, and advanced reactor development. (For preceding period see ANL- 6295.) (J.R.D.)