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.

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 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.

The Homogeneous Reactor Test (HRT) is the experimental reactor facility (Frontispiece) being designed and constructed at ORNL as the next step in homogeneous reactor development between the 1-Mv HRE and a "full-scale" power station. The HRT will provide an integrated test at 5 to 10 Mv for the flowsheet and equipment designs on which the full-scale effort will be based. Furthermore, its design is such that several homogeneous systems which require essentially the same operating equipment may be tested with comparatively minor modifications of the original reactor installation. The reactor will be assembled in the building which housed the HRE, located in the experimental reactor exclusion area approximately one mile south of the oak ridge laboratory. (See figure 1) / It is the purpose of this report to provide information with which the hazardous aspects of this reactor may be evaluated. Briefly, it will be shown after a statement of purpose and a general description of the reactor that: 1. The design characteristics and equipment requirements are such that escape of highly reactive material from the reactor piping is unlikely. 2. Should the entire core and blanket contents suddenly escape from the reactor system, a seal-welded steel tank surrounding the …

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

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.

The absorption in lead of Bremsstrahlung X radiation from a Sr^90 TiO3 pellet in the proximity of Hastelloy "C" was measured. The tenth value layer of the more energetic components of the X-ray continuum was determined to be 1.60 inches.

In a gas-cooled reactor operating at very high power density the thickness of the reflector may be determine by the requirement that the steel pressure vessel be protected from an excessive dose of fast neutrons, rather than by the usual requirements of neutron economy and power distribution. It is important the the reflector not be made thicker than necessary, since an increase in pressure vessel diameter can result in a marked increase in cost, as well as a decrease in the permitted gas pressure level.

The equilibrium and maximum override values for xenon and samarium poisoning have been computed using the recently issued effective cross sections of C. H. Westcott. Values are given as a function of specific power, neutron temperature, and epithermal flux content.

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

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.

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.

The successful completion of a program of experiments, including the Aircraft Reactor Experiment (ARE), has demonstrated the high probability of producing militarily useful aircraft nuclear power plants employing reflector-moderated circulating-fuel reactors. Consequently, and accelerated program culminating in operation of the Aircraft Reactor Test (ART) is under way. In order to adhere to the compressed schedule of the accelerated program, it is essential that the Atomic Energy Commission approve the 7500 Area in Oak Ridge as the test site by February15, 1955. This report summarizes the hazards associated with operating the contained 60-Mv reactor of the ART at the proposed Oak Ridge test site.

"An analysis is presented of the accidental release of activity following the operation of the NS "Savannah" at the New York Shipbuilding Corporation docks in Camden, New Jersey. Although a number of accidents are considered, the report is primarily concerned with the environmental activity levels and subsequent exposures which would result from the "maximum credible accident" (p. v).

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.

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 …

A review of helium sources, availability, consumption, and future production capacity indicates that the helium consumed in the operation of 100 helium-cooled reactors for 300-Mwe power plants over a 20-year period will run no more than a few per cent of the helium consumed in the U. S. in the next 25 years and less than 1% of the helium that is to be stored during that period under the helium conservation act of 1960 (Public Law 86-777).

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.

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.

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 …

Simulated reactor fuel solutions were circulated at temperatures as high as 365°C in a small titanium pump loop. A hydroclone separator separated heavy phases formed at high temperatures. As the temperature of the solution was increased beyond the two-liquid-phase temperature (327°C), the salt concentration of the light phase decreased and the acid concentration increased. The mole ratios of uranium to sulfate, uranium to copper, and uranium to nickel in the light phase decreased in the same proportion in the temperature range of 330 to 365°C. Corrosion of titanium and Zircaloy-2 specimens was insignificant during the relatively short exposure periods.

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.

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.

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.