Report issued by the Oak Ridge National Laboratory discussing the vibrational analysis of the molecular spectrum of polonium. Experimental procedures, results, and analysis are presented. This report includes tables, illustrations, and photographs.

Report documenting the design and testing progress of the Oak Ridge National Laboratory's Gas-Cooled Reactor Program.

Report containing a survey of the radiation from the nuclear ship Savannah in order to determine the dose rate for people aboard.

From Summary: "The major objective of the run was the investigation of fuel stability. The reactor operated for long periods at the design power of 5 Mw with none of the usual indications of instability while the system pressure was kept at 1250 psig. Run 21 ended on January 22, so that the reason for an abrupt change in the mixing rate of fuel between the core and blanket could be investigated and a reactor steam-system valve could be repaired."

From introduction: "Cytological examinations of the irradiated and some unirradiated populations in the radioactive sediments of White Oak Creek and the Clinch River were made."

From abstract: "The probability for a fission neutron to escape fast leakage from bare, hydrogen moderated reactors is calculated by a method utilizing only the microscopic cross section of the materials. These results can be employed to determine the effectiveness of other substances in preventing fast neutron leakage. These calculations are carried out for aluminum and iron."

From introduction: "This report covers work performed in the Solid State Division for the quarter ending May 10, 1952." Topics covered include radiation metallurgy, engineering properties, solid state reactions, crystal physics, and special projects.

An inconel loop circulating fluoride fuel (62 1/2 make [unintelligible] NaF, 12 1/2 make [unintelligible] ZrF4, 25 make [unintelligible] UF4, 92 [unintelligible] enriched) was operated at 1485°F with a temperature difference of about 35°F in the Low Intensity Test Reactor for 645 hr. For 475 hr of this time the reactor was at full power, and fission power generation in the loop was 2.7 kw, with a max length power density of 0.4 kw/cc. The total volume of fuel was 1290 cc (5.o kg [unintelligible] and the the flow through the irradiated section was 8.6 fps (Reynolds number 5500). The loop has been disassembled and has been examined by chemical and metallographic analyses. Ne acceleration of corrosion of decomposition of fuel by irradiation was noted, although deposition of fission-product ruthenium was absorbed. Ne mass transfer of Inconel was formed, and the corrosive [unintelligible] was general and relatively light. The average corrosive generation, in the usual form of subsurface yields, was 0.5 [unintelligible], the maximum penetration was 2 to 3 miles.

The feasibility of determining particle sizes in the submicron range by employing an activation analysis - centrifugation method has been demonstrated. It is believed that this method is now applicable to the analysis of thorium oxide for submicron particles. The same techniques are, in most instance, usable in determining particle sized in other sample materials.

Catalysts for use in recombining the gases produced by the radiolytic decomposition of water in thorium oxide slurries under neutron irradiation were investigated in out-of-pile tests using stoichiometric mixtures of hydrogen and oxygen. Most favorable results were obtained with a molybdenum oxide catalyst. Satisfactory rate also were attained with palladium and silver oxides. Copper, nickel, vanadium and chromium compounds were less effective.

A promising nonaqueous process for the recovery of uranium from spent fuel elements is under development at Oak Ridge National Laboratory. This process consists of dissolution of the fuel element in a fluoride melt by hydrofluorination at 600 to 700°C, direct fluorination with fluorine for the production and volatilization of UF6, with further decontamination of the product UF6 from fission product activity being secured in a NaF absorption-desorption step. Good decontamination is obtained in the fluorination step due to the low volatility of most of the fission product fluorides. An over-all decontamination factor greater than 106 with adequate uranium recovery has been demonstrated in laboratory scale tests using a double bed procedure for the NaF step. A pilot plant has been constructed for testing the process with various heterogeneous fuel elements. The engineering and operational features of the pilot plant are described

Thorium and thorium-uranium oxide slurries were irradiation in the Low Intensity Test Reactor (LITR) at temperatures up to 300C in small stirred autoclaves. Stirring was accomplished by means of an electromagnetically operated lunger. Stirrer operations was monitored suing an oscilloscope. Relative slurry viscosities were determined both in and out-of-pile using calibration curves of apparent viscosity versus stirrer rise time. Post-irradiation examination of selected slurries indicated no gross changes occurred in the particulate properties.

A promising scheme for the chemical processing of a thorium breeder reactor of the two-region aqueous homogeneous type consists of the following operations: concentration of insoluble fission and corrosion products from the core system into a small volume of fuel solution, combining this slurry with irradiated thorium oxide slurry taken from the blanket, recovery of D2O by evaporation, dissolution of the thorium and uranium in HNO3, and, after a suitable cooling period, recovery of the uranium and thorium by solvent extraction for return to the reactor. The use of a hydroclone and underflow container arrangement for concentrating insoluble fission and corrosion products under simulated reactor conditions has been successfully demonstrated on dynamic loops. Solids concentration factors greater than 103 were demonstrated, and equilibrium solids concentration in the circulating solution less than 1 ppm was attained in these tests. Present data indicate that proper design and operation will minimize solids deposition in the reactor system and that the insoluble impurities can be effectively removed by the hydroclone. An alternate method of processing the slurry removed from the core system by the hydroclone consists of removing the room temperature insolubles by centrifugation, recovering the uranium from the supernatant by peroxide precipitation, thermal …

When it was discovered that two HRT flange bolts of a lot of 16 spares contained serious cracks, a program was launched to (1) determine the cause for the cracking, and (2) find methods for non-destructive testing the remainder of the 672 bolts shipment, a large portion of which had been installed in the HRT. Concurrently, inspection of 8 ferrules removed from an HRT flange revealed hairline cracking in 4 of them. Magnaglo, a magnetic particle inspection method using a fluorescent dye, proved to be the only definitive method for inspecting the bolts. The evidence gathered on the bolts pointed to quench cracking as the cause for the defects. Nothing abnormal was disclosed in regard to the bolt material. The alloy and heat treatment at present prescribed for the HRT bolts and ferrules are considered suitable. However, recommendations are made for plating with zinc, instead of formerly prescribed cadmium, to a thickness of 0.0002 inch, followed by a hydrogen relief treatment and a final bichromate chemical dip.

A preliminary study of molten salt power reactors was made. The most promising fuel carrier salts were the fluorides and chlorides of the alkali metals, zirconium, and beryllium. The chlorides were found to have lower melting points but were less stable and more corrosive than the fluorides. A Li/sup 7/ F- - BeF/sub 2/ mixture with ThF/sub 4/ and UF/sub 4/appeared to perform best. Of the numerous alloys tested as container material, Inconel and a nickel-- molybdenum alloy INOR-8 appeared to be the most resistant to corrosion. To study the performance, safety, economics, and construction costs of a typical molten salt reactor, a reactor of specific type and size was chosen for study. The reference design reactor was a two-region homogeneous converter with a core salt of 70 mole% Li/sup 7/F and 30% BeF/sub 2. ThF/sub 4/ and enough VF/sub 4/ for criticality were added. Study indicated that a molten salt reactor would produce economical power, but the problem of developing a salt core and a container metal which would last for many years of operation needed further study. (M.C.G.)

Run SM-2 was run to determine whether a sulfated ThO2 slurry could be handled in a hydrodynamic system similar to the HRT test blanket. It was found that the ThO2 concentration circulating in the pipes was consistently 50% or less of the expected concentration based on the quantity of the oxide changed. The run lasted 1730 hours. It was terminated because of a slurry leak a few days before a shutdown had been scheduled. Severe erosion was found in the pump impeller and flow nozzle . Chloride concentration high enough to cause concern over possible stress corrosion cracking occurred on several occasions in the pressurizer.

It is concluded that an excess of O2 must be added to the HRT fuel circulating stream in amounts sufficient to recombine the D2 in dead-end lines and serve as corrosion protection.

The leak detector system consists of one gas pressurized reservoir containing heavy water, a tubing manifold connecting the pressurizer to six separate lines each connected to one of the flanges, tubing lines leading from the second hole on each of three flange pairs (dome and heat exchanger flanges) back into the instrument room, plus required valves and fittings. A schematic diagram of the system in included.

Either system appears to be fairly satisfactory from a containment standpoint. Current results indicate probable over-all rates of about 0.2mils/mo for titanium vs. 1.5-3.0 mils/mo for Ni-o-nel. Tests are not 100% comparable due to changes made in flowsheet conditions, but have been of sufficient variation and length as to allow good predictions to be made. Both metals show some tendency toward local attack in Thorex solutions. These tendencies are increased by poor welding techniques.

Equilibrium loading of uranium on Dowex 21K has been studied in a sulfate system for uranium concentrations from 0.0005 M to 0.0005 M, total sulfate concentrations of 0.45 M to 0.6M, and sulfuric acid concentration of 0.020 M. Loading data have been fitted to Langmuir adsorption isotherms and Langmuir constants have been evaluated. Resin was equilibrated with uranium feed solutions by flowing the feed through a shallow fixed bed of resin.

In the preliminary stages of getting up a time-of-flight system for measuring neutron spectra from proton reactions, a study of the time dependence of the beam in the 86Inch Cyclotron was made. This study revealed the expected bunching of the protons to produce a short burst of beam on each cycle of the 13.4 Mc/s accelerating voltage. In addition to the 13.4 Mc/s structure, however, there was a 360 c/sec modulation of the beam pulses and a complicated pattern built upon that.

A chemical flowsheet is proposed for recovery of strontium and rare earths from Purex wastes. The iron in the waste is first complexed with tartrate and the pH is adjusted with caustic. Strontium and rare earths are extracted by a solvent comprised of di(2-ethylhexyl)phosphoric--sodium di (2-ethylhexyl) phosphate--tributyl phosphate -- Amsco 125-82. and are stripped with nitric acid. Processing the strip product through additional solvent extraction cycles yields isolated, concentrated strontium and rare earth fractions.

After shutdown heating rates have been calculated for the target, control plates, and the beryllium reflector of the HFIR. Hilvety previously calculated the after shutdown heating rates in the element and his results are reported in ORNL CP-60-4-110. Decay times of 1.0 10, 10^2, 10^3, 10^4, and 10^5 seconds have been considered, and heat fluxes have been computed for all of the mentioned components. The greatest heat fluxes were found to be at the surfaces of the control plates and the permanent beryllium reflector.