Technology of the Sodium Graphite Reactor. Reactivity calculations were made to study the application of steadystate plutonium feedback techniques to the use of diffusion plant tails for reactor fuel feed material. The performance and design of a twin core SGR power plant are given. Thermal neutron flux distribution measurements are reported for a six-rod fuel cluster and for a hollow uranium rod. A power cost calculation was made for a 1000-Mw SGR Th-U/sup 233/ breeder reactor which starts up on Th--U/sup 235/ alloy. Calculations were made on neutron leakage through the SRE shield. Research on reactor fuel elements and reactor materials are described. Corrosion and irradiation damage data at 5 x 10/sup 7/ r dose (150 deg F) on toluene as the SRE shield coolant indicate that the radioinduced corrosion of Fe, Al, and Cu in the SRE shield should be negligible. Preliminary results are summarized for l-Mev electron ir radiation studies of terphenyls at 400 to 450 deg C. Sodium Reactor Experiment. Progress is reported for various portions of the SRE project: reactor design and evaluation, fuel elements, moderator, reflector, structure, reactor cooling and heat transfer, instrumentation and control, shielding, and reactor services. (D.L.C.)

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This report summarizes results of measurements of density, viscosity, and surface tension of light and heavy water solutions of uranyl sulfate at elevated temperatures, which measurements were made at Mound Laboratory for the Homogeneous Reactor Project at Oak Ridge National Laboratory.

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An isothermal loop for testing a full-scale sodium pump for SRE and associated instruments has been operated for ~ 600 hrs. A summary of data obtained, together with recommendations, is given. (auth)

It was demonstrated by differential thermal analysis (DTA) that: 1. Catastrophic amounts of energy can be stored in diamond. 2. Even at low irradiations, the release takes place over several hundred degrees, indicating a spectrum of activation energies. 3. At higher irradiations, the stored energy release is considerably less than the increased energy content and seems not to have been completely released even at the highest temperatures reached. 4. There is some indication of an increased heat capacity below the temperature of stored energy release. It was shown by DTA that large amounts of energy can be stored in silicon carbide on irradiation. The release was found to be spread out over a greater range of temperatures than in diamond and indicated a larger and higher group of activation energies. Catastrophic release was not achieved. The amount of stored energy released over the range of temperatures used was 140 cal/g in a sample irradiated in a water-cooled testhole at HEW for an exposure of 265 Mwd/aT. (auth)

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Reactivity calculations have been performed for the steady-state Pu feedback technique outlined in the previous progress report. A full-scale power plant study was initiated, based on sodium-graprite technology. A twin-core power plant is now considered to be the most promising configuration. Several design drawings are given of such a reactor, using slightly enriched U to produce Pu amd electrical power. The thermal neutron flux distribution in a cluster of 6 U rods was measured, and the results are compared with previous measurements for 7 rod cluster. The average thermal cycling of hollow U slug elements was begun. Results are given for 500 cycles between 100 and 500 deg C. A series of powder- compacted U alloys were thermal cycled between 200 and 700 deg C. Data on the transfur of radioactivity from Zr by Na has been obtained from a capsule of the first series of three miniharps. Fe, Al, and Cu were immersed in toluene end irradiated at 150 deg F in the MTR-Gamma canal. Toluene is being considered as a shield coolant for the SRE. The effect of 1-Mev electron irradlation on terphenyls was also studied. A venting tube arrangement has been designed for the Zr-canned graphite moderator. …

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