PROGRESS RELATING TO CIVILIAN APPLICATIONS DURING APRIL 1959

5 8 5 of 15% cold-worked Zircaloy-2 as material for process tubes for the NPR has indicated the need for study of the creep properties at elevated temperatures. Single crystals of high-purity Mo are being tify factors affecting irradiation-induced volume changes in graphite by means of sink-float density measurements was continued. The simulation of conditions after lossof- coolant incident in the PRTR by means of a digital computer was continued. The study of the radiometric analysis of Mg was resumed. The program on radiationinduced graft polymerization ss continuing with emphasis on the investigation of factors influencing the formation of free-radical and peroxy grafting sites. A study of the effect of gamma radiation on nitration reactions in the HNO/sub 3/ -cyclohexane system is reported. The manner in which U metal solidifies in cylindrical graphite molds is being studied. A study to determine the feasibility of coating Ni and Ni alloys with Ca by the arcspraying method is presented. A project to investigate the effects of Y/sub 2/O/sub 3/, La/sub 2/O/ sub 3/, and CaO additions to UO/sub 2/ with regard to stabilizing the UO/sub 2/ fluorite structure under both oxidizing and reducing conditions is presented. An evaluation is being made of the changes in the mechanical properties of AISI Type 347 stainless steel after exposure to a fast-neutron flux at ~ 120 and 600 F. Several Nb-base alloys are being evaluated for applications as alternate cladding materials in future EBR cores. Alloys selected for study include Nb-Cr, Nb-Zr, Nb-Ta-Cr, Nb-Ti-Cr, Nb-Ti-Al, unalloyed Nb, and a comparison alloy of V-Ti-Nb. A program of research designed to secure a basic understanding of the parameters involved in the friction and wear behavior of rubbing surfaces lubricated by high- temperature Na is in progress. Corrosion data are presented for U-Nb alloys in air, water, and steam. Development of Th-Ubase alloys with improved irradiation- damage resistance and corrosion life is being sought by means of ternary and quaternary alloying and process control. A study is presented of gas release from sintered UO/sub 2/ bodies during postirradiation heattng and during actual exposure to neutron flux in the BRR. Techniques are being developed for the fabrication of high-density cermet elements consisting of 60 to 90 vol.% of UO/ sub 2/, UN, or UC combined with stainless steel or Nb. Ceramic fuels and Nb- and Mo-base cermet materials are being clad with Mo and Nb by use of the gas-pressure- bonding process. Techniques for the productton of UC of 95% of theoretical density or better by powder metallurgy is being investigated. Fatigue studies of Inconel and INOR-8 were continued. A fundamental study is being made of the kinetics and mechanisms of the reaction of N/sub 2/ with Nb. The constitution of U-Nb alloys is being investigated by means of diffusion couples to establish the composition limits of the gamma-phase immiscibility gap in the system. Evaluation of UC/sub 2/-graphite spheres by measurement of postirradiation fission gas release at elevated temperatures was continued. Ni-o-nel specimens were exposed to boiling Sulfex-Thorex process solutions containing dissolved type 304 stainless steel. Titanium is being evaluated as a material of construction for the Darex-Thorex dissolution process. A series of Ta-alloy strsp specimens containing additions of either C, Re, or Y was tested for Pu-alloy compatibility. The effect of irradiation on Ta 0s being investigated. The studies concerned with the developmeni of a platetype oxide fuel element for the PWR were continued. Techniques are being developed for coating of UO/sub 2/ cores with graphite, carbon, and chromoium to prevent reaction between the UO/sub 2/ cores and Zircaloy cladding. Fuel element cores of UO/sub 2/ particles dispersed in a densel