Development progress is reported on fast reactors, liquid metal cooled reactors, ZPR-III No. 22 and 44, Z PR-VI No. 1, ZPR-IX, Borax-V, Faret, EBR-I, EBR-II, treat, Fermi Fast Breeder Reactor, critical assemblies, Argonne Advanced Research Reactor, EBWR, magnetohydrodynamic cells, thermionic cells, fuel cells, and boiling water reactors. Reactor technology is reported on fuel development, physics, heat and fluid engineering, materials development and properties, chemical separations, nuclear safety, and corrosion testing. (N.W.R.)