For Co60 source at 15 meters, the air-scattered gamma dose rate predicted by theory is excerpted from ORNL-1575, pp. 167-203. This is compared with experimental measurements for the same source and comparable geometry reported by Convair in CVAC-170T. After applying an appropriate correction for ground scattering as estimated in Mart-55-16T (Convair), the two results are found to be in substantial agreement.

The Aircraft Reactor Experiment (ARE)was successfully concluded in November of 1954, and a detailed report of the operation was published the following year. At that time it was thought that an extensive examination of the reactor and system components after disassembly was warranted. It was realized, of course, that the level of radioactivity of the components would necessitate extensive delays in the examinations. Since examination of a few critical ARE samples showed nothing unexpected, much of the planned hot-cell inspection was postponed and complete examination of all but a few specimens was indefinitely suspended. The few examinations that were completed are described in this report, along with a description of the disassembly of the ARE system. Diagrams of the fuel system, sodium system, and off-gas system are presented in Figs. 1, 2, and 3 for reference use in visualizing the disassembly process.

Progress report of the Oak Ridge National Laboratory Biology Division providing updates on various projects, experiments, and other work. This report includes a summary of scholarly output from the division and departmental activities in cytology and genetics, mammalian genetics and development, microbial protection and recovery, mammalian recovery, pathology and physiology, general physiology, biochemistry, enzymology and photosynthesis, microbiology, plant biochemistry, and biophysics.

Two revised Excer process flowsheets are presented for the production of UF4 from urnayl nitrate solution. In both, the uranium is sorbed on a cation-exchange resin and eluted with aqueous HF. In one, the resulting UO2F2 in dilute HF is mixed with dilute sulfuric or hydrochloric acid and electrolytically reduced in a cation-exchange-membrane cell, and the precipitated UF4·0.75H2O is dried and dehydrated to anhydrous UF4. A cost of 20¢ per pound of reduced uranium is estimated. In the other, ammonium fluoride is also added to the uranyl fluoride solution before the electrolytic reduction step, and the precipitate is UF4·04NH4F. A flowsheet for preparing UF4 from raw ore is also shown. The uranium is sorbed on an anion-exchange resin from a sulfuric acid leach liquor and eluted with dilute HCl. Ammonium fluoride and HF are added to the UO2Cl2-HCl solution before the uranyl ion is electrolytically reduced to precipitate UF4·0.4NH4F. Decontamination factors as high as 45 and 9 for gross beta and gamma activities and of 10 to 5000 for light metal impurities were obtained in the electrolytic reduction step.

Gram amounts of americium were separated quantitatively from kilogram quantities of lanthanum to yield an americium product approaching 90% purity. The remaining impurity was chiefly yttrium. Elution of americium from 25% loaded Dowex 50 resin column with 0.15 M citric acid— 0.10 M diammonium citrate — 0.3 M ammonium nitrate, pH 3.3 gave a product containing 99% of the americium with a La/Am ratio of 1/100 or less in one fourth of a column volume, in this case about 1 100-fold volume reduction. Approximately 9 g of americium was purified by this method. Elution with 12.8 M hydrochloric acid from a 20 to 30% loaded column gave 90% of the americium in two column volumes of product with a La/Am ratio of about 1/4. About 1 g of americium was purified by this method.

Much of the shielding work carried out with the Bulk Shielding Reactor (BSR) has yielded data of particular interest for the design of swimming pool type reactors, However, it is often difficult for a reactor designer to locate such data since it may be recorded in a report primarily concerned with shielding problems. Therefore, this memorandum presents a bibliography of reports from the Bulk Shielding Facility arranged according to the application of data to the various aspects of reactor design.

Semiannual Progress report of the Oak Ridge National Laboratory Chemistry Division providing updates on various projects, experiments, and other work in inorganic and physical chemistry, nuclear chemistry, organic chemistry, chemical physics, chemistry of separation processes, radiation chemistry, and reactor chemistry.

The reactor equipment cell is expected to be completed by February 15. While filled with water, the tank was inspected for leaks, and the few leaks found will have been repaired by February 15. All orders for construction materials placed prior to this quarter have been received. New requisitions issued during the quarter total $16,000. Work orders were issued, and fabrication of all low-pressure-system components was begun in the ORNL shops. The thermal shield around the reactor vessel was specified as a 2-ft-thick cylindrical concrete wall. With this shield, the fast-neutron flux in the equipment area will be reduced to 7 x 109 neutrons/cm2/sec, the slow flux to 4 x 107 neutrons/cm2/sec, and the gamma intensity to less than 105 r/hr. The possible blast effects from a rupture of the pressure vessel were studied and are judged to be sufficient to justify the inclusion of a 1.5. to 2-in.-thick blast shield around the pressure vessel. The blast shield eliminates the danger of damaging the leak tight equipment-cell liner. Pressures in the reactor equipment cell, as a result of vessel failure, were calculated in order to arrive at a safe design pressure for the reactor equipment cell. For the case of …