Chloride-induced stress-corrosion cracking has been encountered in the Homogeneous Reactor Test during the preliminary testing. The rector is constructed of austenitic stainless steels. It is unique in that it will operate at 250 to 300 C with an aqueous uranyl sulfate solution fuel containing 200 to 500 ppm of dissolved oxygen. The cracking has occurred in a secondary system used for detecting leaks in the flanged joints of the primary systems and in the grooves of flanges in the primary systems. Tubing used in the leak-detection system was found to be contaminated with chloride introduced during manufacture.

A second test of the mockup of the Zircaloy - stainless steel transition joint as used in the HRT reactor vessel has been completed. The joint and bellows have now received 104 thermal cycles and 148 mechanical deflections. The joint and bellows have functioned properly; corrosion damage has been negligible, except for a small area on the bellows which has undergone pitting attack. Long-term runs with uranyl sulfate solutions of the concentration proposed or use in the HRT have shown the solution to be stable at 300 C. Substituting heavy water for normal water caused no difference in either corrosion or solution stability. Experiments in which chromic acid was used to pretreat stainless steel have shown that, under certain conditions, the pretreated film can exist in uranyl sulfate solutions at flow rates in excess of the critical velocity for relatively long periods of time. The practicability of using titanium inserts in high turbulent areas of stainless steel loops to minimize corrosion has been demonstrated. The corrosiveness of beryllium sulfate solutions containing dissolved uranium trioxide has been determined at 250 and 280 C. Laboratory studies with regard to stress-corrosion cracking have shown that high stressed type 347 stainless steel will crack …

A system for concentrating uranyl nitrate solutions was designed and installed in the Thorex Pilot Plant. A total of 16,060 g of uranium was concentrated in the system in 68 batch runs. A total of 14,400 g total uranium (14.180 g U/sup 233/) was recovered as product suitable for shipment. Uranium loss to the evaporator condensate was 0.03% of the total uranium processed. The material balance across the system was 98.4%. The average concentration of uranium in the evaporator feed solution was 29 g/liter; the average concentration in the evaporated solution was 298 g U/liter and in the product solution was 199 g/liter. Radiation readings of bottles containing product solutions were taken with a hard-shell cutie pie immediately after each run, and these readings ranged from 35 to 1100 mr/hr. The radiation levels of the bottles of product solution shipped averaged 78 mr/hr. Bottles of product solution reading in excess of 300 mr/hr, maximum allowable for shipment. were reprocessed in the second-cycle solvent extraction system (Thorex) and reconcentrated. The products from seven runs had radiation levels in excess of 300 mr/hr at the time of concentration, or the activities had grown to that level by the time of shipment. The …

The following temperature measurement tabulation consists of two parts. Part I lists all HRT thermocouples, their location, the junction box thru which the leads pass, and their termination, if on an instrument. Part II lists all temperature read out instruments and their location. A total of 577 thermocouples are listed in this tabulation. The roughly 77,000 ft of wire used in connecting them up cost $6,799. Temperatures are read on 24 instruments. Cost of these was approximately $15,688. Accessories such as patch panels, conduit, disconnects, etc., used in installing the thermocouples cost about $8,069. Total cost for material and instruments for temperature measure comes to approximately $30,556.

An estimate has been made of the gamma radiation levels at access holes in the HRT Shielding when the plugs have been removed to service or maintain the reactor. In every case the radiation level at the holes was greater than the maximum permissible exposure rate of 0.3 roentgens per week. The radiation through the holes can be attenuated to some extent by flooding the reactor cell up to the flange to be disconnected. However, shielding would still be required and it is more practical to provide a small additional shield thickness to compensate for the moderate attenuation that could be gained from flooding.

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.

The horizontal and vertical power distribution for a 5 x 7 fuel element loading of the TSR is presented. (auth)

Short reports to the members of the Nuclear Cross Section Advisory Group from three groups: (1) High voltage group; (2) Fast chopper time-of flight spectrometer; and (3) Electronuclear research division.

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.

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.

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.

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.