Techniques are described for determining U-235 abundance by measurement of the intensity of 0.18 Mev gamma radiation. One method involves measurement of the ratio of the intensity of 0.18-Mev radiation to that of 0.1 Mev radiation. The preferred technique consists of chemical separation of uranium followed by direct counting of 0.18-Mev photons. Application has been made in analysis of uranium samples of abundances in the range of 0.05% to 93%. Accuracy appears to be better than 3% if the abundance is between 0.7% and 100%. Findings in the self-absorption of 0.18 Mev radiation in uranium oxide are presented.

This technical report is the second of a series which concerns the separation of ions by solvent extraction with trialkyl phosphine oxides (TOPO). This investigation has consisted in the extraction of various ions from acidic solutions with extractants that are representative of these ore specific phosphine oxides - triphenylphosphine oxide (THPO) and tris-2-ethylhexylphosihine oxides (TEHPO). In general it is observed that: (a) the order of increasing capacity of extraction is THPO > TOPO >TEHPO. (b) No ion is extracted by THPO or TEHPO that is not extracted by TOPO under certain conditions. (c) The effect of hydrogen ion concentration is greater in TEHPO systems than it is in the other two, which indicated greater selectivity of extraction with TEHPO.

Twenty-five hundred psi ring-type flanges, ring gaskets, bolts, and special connectors were tested for adaptability to the aqueous homogenous reactor. High pressure line closures were studied to obtain empirical data pertinent to the selection or design of a connector capable of withstanding sustained thermal cycling and high pressures encountered in the aqueous homogenous reactor. Specialized stress-strain measurement techniques yielded information concerning flange deformation, ring type gaskets, bolts, and special connectors. The results indicated that no totally acceptable connector is currently available. Most promising of the combination of components tested during this period was a 2500 psi ring type flange with an accurately machined octagonal gasket and Grade B-7 bolts.

Resistance of carbon steel to corrosion in oxygenated high-temperature (250C) water was unexpectedly good at high oxygen concentration. Pertinent literature, critically examined, and toroid experiments indicted that at low oxygen concentration attack did increase with concentration, but as oxygen concentration was sufficiently increased, more protective films were formed on the metal. Some corrosion factors in the application of carbon steel to nuclear reactors systems are discussed.

The HRT refrigeration system was designed to use Freon-11 (CCI3F) as the refrigerant material in the secondary loop. A Van de Graaff irradiation of this material indicated that serious corrosion problems were probable if Freon were used in the proposed metal system. A survey was made of candidate refrigerants, and Amsco 125-82 and triethyl phosphate were selected for irradiation and physical-property determinations.

In order to evaluate the behavior of an APPR type absorber rod, an irradiation test program has been established. Approximately 21 more samples are planned for testing under this request. The request proposes testing a full size APPR-1 type control rod in the MTR. The objective of the test is to better evaluate the neutron absorbing material proposed for the APPR-1 control rod.

A method was developed for calculating shield induced gamma radiation escaping through openings in a biological shield. The method was applied to the HRT and the results indicated that the contribution to the dose from induced activity in the HRT shield was around 0.1 r/hr and was insignificant in comparison to to other mechanisms contributing to the escape of gamma rays through shield openings.

A new type of continuous density meter, applicable for use with ThO2 slurry in high temperature-pressure systems, was tested successfully in a low temperature slurry loop.

The results of an examination of "O" ring gaskets remove from the HRT following a discovery that the water in the leak detector system contained 1000 ppm chloride are presented.

A six-inch diameter "O" ring from the HRT Mockup was examined metallographically after 2452 hours exposure to uranyl sulfate solution at 300C. surface defects, except for cold work defects were found only in areas exposed to uranyl sulfates. Defects found were pits, transgranular cracks, surface cracks, and grain attacks.

It is the purpose of this memo to clarify and revise burnup calculations for the APPR irradiation program and to present a proposed irradiation schedule. the report will also be in the nature of a review of the program.

Loop L-4-12 was the seventh corrosion test loop operated in HB-4 beam hole at the LITR. The loop was inserted on January 24, 1956, and removed on April 17, 1956. This loop had a titanium core which was attached to the 347 stainless steel loop with special titanium to stainless steel couplings.

A prototype sampler for obtaining samples of high radioactive UO2SO4 solution for use in the HRT is presented. It was successfully operated in conjunction with a low pressure water system and a high pressure, high temperature UO2SO4 system.

The criteria for selection of an HRT secondary refrigerant system refrigerant to replace Freon-11 are given. The properties of Amsco which make it desirable are tabulated and it is compared with triethyl phosphate (the second choice) and Freon-11.

In order to test the operation of a freeze jacket in air with the process fluid closely following the conditions found in the high pressure circulation loop of a homogeneous reactor, or, 2000 psi and 300C, a test loop was built and used in conjunction with existing refrigeration equipment. The freeze jacket was made of 5/16-in. type 346 stainless steel tubing wrapped around and welded to a 1/2-in. stainless steel process line. It was concluded that for these reactor operating conditions, only a small leak rate, 11 cc/min, could be frozen off. It is recommended that, at the beginning of the the freezing operation, the temperature of the secondary refrigerant entering the freeze jacket be at least -40C and that the freeze jacket be made as long as practical.

The operation and design of a high pressure recombination loop for the recombination of H2, D2, and O2 produced by the radiolytic decomposition of water which is used a solvent for fuel in the homogeneous reactors are presented.

Few data exist for the thermal conductivity and viscosity of gases at very high pressure. The possibility of using gases for heat transfer media at pressures up to 100 atmospheres and above raised the problem of estimating variations in the conductivity and viscosity at high pressure. Generalized plots are presented which are based on the work of Enskog, Eucken, and Hirschfelder et al. Some pertinent data from Hirschfelder et al and from Hilsenrath et al are presented.

The heat transfer and fluid friction characteristics have been determined for a liquid flowing parallel to the tube bundle of a heat exchanger consisting of one hundred and two 1/16-inch O.D. tubes arranged in a delta or triangular array. These results may be expressed by empirical equations.

Some refined calculations have been made, relative to a proposed delay prior to a dump, to determine the expected D2 concentration in the vent stream from the pressurizer gas bleeds during a dump of the Homogeneous Reactor Test (HRT). These calculations indicate that for vent valves have a Cv of 0.07 (venting time from 2000 psia to D2O saturation pressure of approximately 12 minutes), a delay period is not required since the D2 concentration is well below lower explosive limit. For vent valves having a Cv of 0.3 (venting time approximately 2.4 minutes), the calculation indicate that a delay before venting of approximately two minutes will be required. This is due entirely to the possibility of mass ebullition the D2. Since the pressure drops so quickly, the reactor solution becomes saturated with D2 before appreciable recombination can occur.

At the request of the Alloy Preparation Group, the Nondestructive Test Development Group investigated the feasibility of determining the clad thickness on Mark X MTR Fuel Plates. As the use of induced eddy-currents was considered to be the most promising approach, a prototype instrument and probe coil utilizing this principle was developed to measure clad thickness. The results of the investigation conducted with this instrument indicate that the clad thickness of this type of fuel plats can be measured to withing +- 0.001 in.

Calculations indicate that the proposed shielding arrangement will give a dose rate at the surface of the water tank of about 100 mrem per hr., practically all gammas. This is adequate for transportation and handling, but if the radiation actually proves to be this high, a storage location isolated from normal working areas must be provided. The isolation area need not be large, however, since the calculated dose rate at 10 feet from the shielded sources is only 3.5 mrem pr hr. For the short time required to transfer the source from the water tank into the reactor the Pb carrier alone will provide sufficient shielding. At one meter from the source shielded by the Pb carrier, the dose rate is estimated to be 170 mrem per hr., with neutrons contributing he major part. With reasonable care, the operations should be carried out without excessive exposures. The results of the calculations are summarized.

After several failures had occurred in the HRT leak detector system, several lengths of this tubing were removed for metallurgical examination. The tubing was of type 304 stainless steel and was 1/4" in diameter with a 0.065 wall. The tubing had been purchased as three different lots, the first in 45 ft. lengths and the other two as standards lengths. Tubing from the first lot was used primarily for the shield penetration and, therefore, sections of it are present in all lines of the system. It appears that chloride contamination entered the system in a portion of the first lot of tubing used for the shield penetration. The exact source of the chloride cannot be determined, but after considering the results and visiting the manufacturer's plant, it appears most likely the contamination was during the manufacturing process.

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.