The presence of large amounts of plutonium in high exposure uranium will give rise to a large, positive, graphite reactivity, temperature coefficient. This will create control problems in normal operation and also in the event of loss of cooling. Some general suggestions are given for the solution of these problems. The magnitude of the coefficient is probably known within ± 25% at present and a program is planned to reduce this uncertainty. The uncertainty is of minor importance in the operating control problem but of considerable significance in the disaster control problem.

Abstract. While the concept of a biological system as a balanced network of chemical transformations is not a new one, experimental definition of specific systems has been lacking. This paper defines theoretically and experimentally a number of such networks and their behavior and response to some limited environmental changes.

This quarterly progress report of the Aircraft Nuclear Propulsion Project at ORNL records the technical progress of the research on circulating-fuel reactors and ether ANP research at the Laboratory under its Contract W-7405-eng-26. The report is divided into three major parts: I. Reactor Theory, Component Development, and Construction, II. Materials Research, and III. Shielding Research.

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In the past year, exploratory data have been taken to determine the relative solubilities of hydrogen and deuterium in various solvents in the vicinity of room temperature and atmospheric pressure. This investigation is one phase of a program to determine the feasibility of separating deuterium from hydrogen by means of rectified absorption.

In the decladding of stainless steel clad fuel elements with sulfuric acid (the Sulfex process), the loss of core material to the decladding solution is determined by the rate of reaction of the core material with the solution and the time of exposure if the core to the solution. Since very little was known about the effects of irradiation history on the rates at which core materials dissolve in sulfuric acid, the present study was undertaken in an effort to determine the magnitude of such effects. This report summarizes the results obtained to date. Further work is planned when materials of higher burn-up are available.

The tests described in this report were static tests devised to afford a basis for a quick evaluation of the resistance of uranium to attack by lithium. The work was done at the same time as the tests of beryllium, thorium, and various engineering metals in lithium (described in ANL-4990); but the results with uranium are given in the present classified report so that the results of the other tests can be published as an unclassified document. The procedure for carrying out the tests is described in ANL-4990.

Knowledge of the effects of interaction between vessels or units containing fissionable material is important for the safe handling, storage, and shipping of these containers. Expressions for the effect of neutron interaction on criticality have been derived for the cases of bare and tamped spheres as well as tamped, infinitely tall cylinders containing fissionable material. The method considered did not apply to the interaction between bae cylinders. In practice, the interaction between vessels in a separations plant or between storage units in an array more nearly approaches the bare condition than it does the tamped condition. The formulation of a method that is applicable to bare or water-tamped and to tall or short vessels will be presented at this time.

This twenty-sixth quarterly report of the research and development activities of the Radiological Sciences Department, Hanford Atomic Products Operation, as before, includes some items charged to control but included for general interest. Such are identified as "not charged to research". The previous report of this series was numbered HW-41026 January 11, 1956.

The use of process-solution-lubricated sleeve bearings in rotating equipment is quite extensive at H.A.P.O. The difficulty or impossibility of providing contact maintenance, the poor lubricating qualities and corrosive natures of most of the process solutions, in addition to radioactivity, impose stringent restrictions on the selection of materials of construction of these bearings. Prototypical evaluation of materials indicating suitable characteristics in preliminary testing, both in the Corrosion Laboratory and in the bearing test machines, is necessary to establish behavior and compatibility under actual or simulated process conditions. These preliminary tests showed that gold and gold alloys might be used as satisfactory materials for pump bearings under certain conditions. This report presents the test results obtained while testing bearings in pumps prototypical or identical with process plant equipment.

This technical report reports progress in the following areas: (1) Effect of scaling time; (2) Influence of specimen shape; (3) Effect of pretreatment; (4) Possible mechanism of growth; and (5) Future work.

"Magnetic measurements were performance at excitation levels ranging from 4000 to 7600 gauss, to study the dynamic behavior of the magnetic and gradient lengths of the CEA magnet sectors. The influence of the proposed metal vacuum chamber on field and gradient was experimentally determined. Results of measurements made with a 26 in. long grad coil and with small circular grad coils are compared. The reliability of the 26 in. long grad coil is demonstrated."

Paths of trip points of Mach reflections produced by 0.5-oz pentolite detonations have been observed for various burst heights. The slopes, Y, at points on the curved path are found to vary from values of Y predicted from plane shock wave data. This discrepancy is attributed to the shock strength conditions at the early inception of the Mach reflection, which later influence the triple point equilibrium, and in lesser degree to radius of curvature effects.

"The degree of cleanliness is defined, and the methods and materials to be used are outlined for carbon and low alloy steels, 300 and 400 series ferritic and austenitic stainless steels, special Ni-Cr base heat-resistant hard-facing and high-temperature brazing alloys, and some non-ferrous materials."

"A study was made of the effects of temperature, impurities in the hydrogen chloride, flow rates, and niobium content on both the reaction rates and insoluble uranium losses in the Zircex Process is presented."

Thorium nitrate, recovered from irradiated thorium metal processed in the ORNL Thorex Pilot Plant, was converted to thorium oxide and then to the fluoride in one pilot-plant-scale and two laboratory-scale runs. Activity distributions, decontamination factors, and safety of the process are treated. (D.L.C.)

For various reasons it is not possible to leave the uranium or other nuclear fuel in a power reactor until all of it has been "burned up" by fission. In the case of liquid fuel (homogeneous) reactors a small part is continuously bled out, purified and returned. In the case of solid fuel reactors, fuel elements are periodically removed, reprocessed and the "unburned" fuel put back into service. In both cases the purification produces wastes which contain radioactive fission products and transuranic elements, and it is with the disposal of these wastes that we are concerned. For technical reasons, we will limit our consideration to the wastes from the processing of solid fuel elements, and from the processing of the very similar solid "blanket" elements in which fissionable fuel is made from non-fissionable isotopes of uranium and thorium by interaction with neutrons in the outer regions of the nuclear reactor.

Loop L-2-10 was the eighth completed in-pile loop experiment and the first in the HB-2 beam hole at the LITR. The loop was inserted on July 2, 1956 and removed on September 3, 1956. The installation, operation, removal, and general performance of the HRP in-pile solution corrosion loop in the HB-2 beam hole at the LITR are described.

This technical report summarizes some preliminary calculations of fuel exposures attainable in heterogeneous reactors, fueled with a mixture of thorium and U233, moderated with D2O and operated with no net loss in fissionable fuel.

A slurry addition system, a venturi in the circulation loop, and two types of sampling systems were tested with 500 and 800 g Th/kg H2O slurries in the 200 gpm loop at 250 C and 1000 psig. The addition system worked satisfactorily while the venturi gave erratic readings during part of the run. Both the capillary and in-line sampling systems proved satisfactory with the capillary sampler being much easier and more convenient to operate. The addition of uranium to the slurry had no appreciable effect on the handling characteristics, the attack rate on 347 SS, the particle size and crystallite size of the thorium oxide. The attack rate was found to be 1 mpy during the first 100 hours of circulation and decreased to 0.4 mpy at the end of the run.