Uranium dioxide, uranium monocarbide, and uranium mononitride are potentially useful ceramic nuclear fuel materials. This paper reports the results of a determination of the melting points of these materials.

Plutonium Oxide Fuels. Mixtures of PWR grade UO2 containing 10, 20, 30, 40, 50, and 60 w/o PuO2 were sintered in hydrogen for 44 hours at 1600 C to get additional data on solubility in this system. Densities of all the pieces were low, approximately 80 percent of theoretical; however, solid solution formation was complete in every case. The low density material should not affect lattice parameter values, but it did slightly reduce the intensity of the reflections.

This report was written to describe the instrument and test results obtained. It is understandably imperative that such alarming devices be incorporated in various areas of the plant to provide an alarm or warning for increasing dose rate from gauss radiation fields.

Photographic observations of the behavior of uranium dioxide at high temperatures are of great value in designing and evaluating fuel elements. This paper reports the growth of uranium dioxide crystals by vapor deposition during out-of-reactor and in-reactor experiments.

The Atomic Energy Commission has recently developed an enlarged program for the study of graphite moderated, gas cooled power reactor systems. It has been recognized, however, that understanding of radiation damage and radiation induced chemical reactions of graphite at the proposed high moderator temperatures is inadequate and that improved understanding is essential if the design of such reactors is to be optimized. Accordingly, the Atomic Energy Commission requested Hanford to organize a modest research and development program directed toward the study of these graphite problems.

The temperature characteristics associated with the handling of self-boiling radioactive wastes from the separations extraction processes in the Chemical Processing Department have necessitated several heat transfer studies. Earlier studies 1,2,3 defined the feasibility of self-concentration in existing waste storage facilities by determining the rate of heat generation from the decay of stored fission products and by defining the rate of heat loss from existing storage tanks to the surrounding soil.

Recently proposals for justifiable additions to the Plutonium Recycle Test Reactor Complex were presented to the Atomic Energy Commission at their request. In addition to a critical reactivity measuring facility in the fuel element storage basin, the following in-reactor loops were proposed: 1. A high pressure, H2O cooled fuel test loop. 2. A rupture loop to investigate fuel element failures. 3. One or more materials testing loops.

Data has been previously presented to show that aluminum corrosion in high temperature water may proceed with either a parabolic or a linear dependence on time. The rate of the parabolic process is an Arrhenius function of temperature and essentially independent of alloy composition. More recently several aluminum melts have been tested which corrode by a logarithmic rate process.

Ceramic insulated, stainless steel sheathed thermocouples have been used to monitor temperatures of encapsulated uranium specimens, both in-reactor and out-of-reactor. No operational difficulties are encountered at low temperatures, but at a temperature of 700 C or greater, a eutectic is formed between uranium and iron. This reaction destroys protective sheath and results in thermocouple failure. A typical example of the phenomenon has been reported by J.W. Geffard of the Fuels Development Operation. Hanford Laboratories. Tantalum was suggested as a barrier between these metals and an evaluation of this system was made at 500 C.

Water treatment systems for preparing and maintaining high purity water in out-of-reactor or in-reactor test oops are becoming increasingly important. In out0of-reactor experiments the presence of ionic impurities in the water has a marked influence on film formation and corrosion rates. It is therefore , imperative that these impurities be maintained at the lower practical concentration.

A number of the questions which have been posed to us in the subject references are commented upon below. These have been reviewed by personanel of the Research and Engineering Operation and the Facilities Engineering Operation, Chemical Processing Department, and of the Chemical Research and Development Operation, Hanford Laboratories Operation. Particular acknowledment is given G. J Alkire, J. P. Duckworth, J. B. Fecht, R. G. Geier, E. R. Irish, H. M. Jones, G. C. Oberg, A. M. Platt, W. H. Reas, W. C. Schmidt, R. J. Sloat, W. H. Swift, M. T. Walling and L. L. Zahn of these organizations for assistance given assembling this information.

In HAPO solvent extraction processes there are two independent aspects of nitrous acid chemistry. One concern the decomposition of the solvent through nitration reactions and the attendant problems. These reactions are autocatalytic in the presence of nitric acid and have threshold values for both temperature and nitric acid concentration for a given solvent below which nitrous acid disappears and above which it is generated with continuous destruction of the solvent. These reactions are identical to those found in the prior study of the hexone system.

Laboratory studies involving fluid flow through porous media require use of fluids having low dissolved gas content. Water is the major fluid used in various and box model and soil permeability studies carried out by the Geochemical and Geophysical Research group. Tap water supplied to the 222-U Bldg. contains a large amount of dissolved air. Under the reduced pressure encountered during model studies, the air is released from solution and gradually clogs the pores of the sand or other porous material. This, of course. leads to anomalous results and cannot be tolerated in precious studies. A system was required to effectively remove the air and make available a continuous supply of desired water for the model studies.

"The PRTR Pressured Gas-Cooled Loop Facility, or Gas Loop, is an experimental facility to be installed in the Plutonium Recycle Test Reactor for use in studies contributing to advancement of the technology of gas-cooled reactors. The facility will provide an in-reactor loop for studying phenomena occurring under conditions likely to exist in gas-cooled reactors.

Several hollow uranium cores of "C" size I & E diameters were fabricated by cold extrusion (550 to 750 F) at Hunter Douglas Aluminum Corporation. Results show diameter control and reproducibility are excellent. Preferred orientation induced by this process is completely removed by a single standard beta heat treatment.

Decontamination of stainless steel and carbon steel used in high temperature recirculation systems is currently being studied to obtain an effective and economical decontamination process for use in these systems. This report presents the preliminary investigation process which has demonstrated very effective decontamination and is low in cost.

In formulating this general diffusion theory expression which represents the neutron balance in a nuclear chain reactor the following assumptions were made : (1) the medium through which the neutrons are diffusing has a low neutron capture cross section, (2) the region in which the flux distribute is being described is two or three mean free paths from strong sources and sinks or from a boundary. Certainly, is going to the lattice cell of a receptor, both of the above conditions are violated; fuel elements have a large absorption cross section and most lattice cells are only two or three mean free paths to is over-all sites

Plutonium Fuels Development Basic studies. Experiments to determine the effect of plutonium dioxide additions on the sinterability of UO2 have continued. PuO2 has been added to ball milled PWR grade UO2 as a physical mixture, and in the form of the mixed crystal oxide.

The transfer or circulation of raw dissolver solutions containing gross particulate matter presents many problems not easily overcome by standard pumping equipment. In April of 1956 the HAPO concept of a modified Archimedes screw pump was developed. Two basic models, externally powered and driven through extended shafts, were constructed and tested. Operation of these preliminary models was so satisfactory that a third unit, integrally formed into drive motor, was built and placed in extended life test. This report describes construction and testing of the third and final model.

In considering the problems associated with the measurement of SSNM content of Non-Production Fuels, two distinct problems are apparent. The first is the technical problem of obtaining highly accurate measurements in a complicated chemical and physical system. The second is the administrative problem of choosing a measurement system which provides a basic of financial settlement acceptable to both the seller (reactor operator) and the buyer (Commission).

The methods for the separation of the elements from thorium to americium having wide use are those employing solvent extraction techniques (1) (2). During recent years the behavior of these elements on anion exchangers has been studied, resulting in the wide application of these resins to the separation of the actinides (3) (4) (5) (6) (7).

The instability of the steel tank bottom of 113SX waste storage tank was postulated to have been caused by a pressure underneath the steel liner which was in excess of the hydrostatic liquid load of the waste resting on the steel bottom.

In HW-56161(1), the preliminary background, bases, and advantages which could be visualized in the study and establishment of reactor concepts utilizing boiling mercury- 204 were presented. The attractive chemical and metallurgical properties of mercury which make it particularly suitable for use in special non-rigid fuel systems as well as its potential for heat transfer applications were considered to be of significant interest to the Plutonium Recycle Program also, since the issuance of the original document, continued study of the potentials for an economical isotope separations process for mercury has shown attractive possibilities for a method based on photochemical activation (HW-59329). (2) The prospectas(3) for this process appear so favorable that earlier opinions and expectations seem to have been conservative. Although the desired level of initial effort in related studies has not yet been realized, particularly in the area of chemical engineering, reactor engineering, and economics, it appears advisable to revise the earlier document to recognize the impact of the favorable outlook for economical mercury isotope production, to present other related information which has been developed, and to recommend the beginning of a research and development program.

The processing of spent fuels from nuclear power and propulsion reactors is planned by Hanford Atomic Products Operation as part of the Atomic Energy Commission's interim processing scheme. The spent nuclear fuels have cores of UO2, U, or alloys of U-Mb, U-Al, or U-Zr clad in either stainless steel, aluminum, or Zircaloy. This report discusses only the Zircaloy-clad fuels and the applications of the Zirflex Process for dissolution. Zirflex chemical flow sheets are presented as developed by pilot plant operations.