Data on the properties, constitution, compatibility, radiation behavior, fabrication, preparation, storage, and handling of uranium, thorium, and plutonium carbides are reviewed. 187 references. (C.J.G.)

This document details activities of the Fuels Preparation Department during the month of April 1960. (FI)

In the Hanford production reactors, failure of fuel element cladding is known as subcooled burnout since the bulk coolant temperature is below the saturation temperature at time of failure or burnout of the fuel cladding. The heat generation rate at which subcooled burnout occurs, establishes a limit to allowable reactor power level. This document compares present and potential power level limits at the Hanford production reactors with power level limits established by subcooled burnout.

A neutron-sensitive semiconductor counter was constructed by depositing a thin layer of Li/sup 6/F between two silicon surface-barrier counters. Neutrons are detected by observing the alpha + T pair resulting from the Li/sup 6/(n, alpha )T reaction; pulses from the two counters are added, and the sum pulse is amplified and recorded on a multichannel analyzer. Since the sandwich geometry permits simultaneous detection of both reaction products, the magnitude of the resulting sum pulse is proportional to the energy of the incoming neutron. Pulse-height spectra from slow neutrons and monoenergetic fast neutrons. in the energy region 0.6 to 3.5 Mev, were recorded from two counters of this type; in both counters the sensitive area was about 0.7 cm/sup 2/, with a Li/sup 6/F layer of order 150 mu g/cm thick. In all cases. a well defined neutron peak was observed in the pulse-height spectrum. In a typical case the full width at half maximum of the fast-neutron peak was about 300 kev. Counters of this type are relatively insensitive to background effects, notably gamma rays, and thus may prove to be useful in the detection and spectroscopy of fast neutrons. (auth)

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The effect of the many parameters which may influence the failure behavior of coextruded fuel material are being evaluated by Reactor & Fuels Research & Development Operation. This knowledge will be helpful in the design, fabrication, and operation of fuel elements so that the hazards and time involved at failure may be minimized. Many of the various tests performed on unirradiated coextruded fuel material have been in isothermal systems. The tests reported here were performed on power generating coextruded fuel rods. One of the purposes of these tests was to assess the effect of simulated in-reactor power generation and associated thermal gradients and thermal stresses on the defect-test behavior. Another purpose of these tests was to determine the degree of damage that might result to fuel components as a result of interaction (e.g., touching produced by warping or distortion of a failing rod) while at operating powers.

The distortion behavior of graphite as a function of irradiation temperature is reviewed. The behavior of needlecoke and CSF graphite was examined over moderate exposures in the GETR. Results showed needle-coke to be less contracting than CSF. Details of contraction show a minimum contraction rate per 10/sup 21/ nvt at 600 to 800 deg C for both types. Limitations to be placed on the data presented are listed. (P. C.H.)

The gamma heat generations in selected positions of the ETR were measured for Cycles 27, 33, and 34. The measurements for Cycle 27 include data for the clean core and depleted core. Maximum gamma heat generation maps are presented for each cycle along with vertical traverses for all positions monitored. The measurements were made using a graphite- C0/sub 2/ ionization chamber. (auth)

The development of apparatus and laboratory techniques for the study of materials compatibility with 1500 to 2200 deg F potassium was attempted. Techniques for corrosion tab preparation, dry box capsule filling and sampling, and vacuum filling and sampling are described. Apparatus for rotating capsule testing to 2000 F, rotating capsule testing to 2400 deg F, and anisothermal see-saw'' capsule testing is also described. (auth)

The Reactor Nuclear Data Tape Programs were designed to compile and/or modify a nuclear data library tape from basic nuclear cross-section input. It is intended that this cross-section library tape will be utilized to provide up-to- date nuclear data for various reactor codes. Program RNDP was designed to compile an initial tape from certain minimal input data, or to add or delete complete blocks of data from an existing tape. Program RNDM was designed to compile and add to an existing tape macroscopic cross section data consisting of mixtures of microscopic cross sections available on the tape. Program RNOC was designed to modify and copy an existing tape, or to compile a new tape from sets of binary cards punched by Program RNDP. These programs were written using the FORTrAN-II system of automatic coding for the IBM7090. (auth)

Results of studies of the known parameters for direct calcination of plutonium nitrate in an agitated bed and conversion of PuO/sub 2/ to PuCl/sub 3/ by fluid bed processes are presented. A description of the processes and the demonstration equipment is included. The study of variables is discussed along with the parameters and plans for demonstration runs. (J.R.D.)

Experimental results are summarized for investigations on the condenser fluid mechanics of mercury under zerogravity, two-phase conditions. Conditions required for interfacial stability in tubes were determined as a function of tube diameters. Correlated two-phase pressure drop data are presented as functions of tube inlet Reynolds number and vapor specific volume. Flow regime stability was studied under zero-gravity and 2.55-gravity conditions and at various Reynolds numbers. the effect of noncondensable gas on flow performance in mercury forced convection condensers was evaluated. (D.L.C.)

Included are summaries of studies of: DCX-1 operation and performance; DCX-2 design and engineering; plasma physics; vacuunn arcs; ion production; acceleration and injection; plasma theory and computations; instrumentation; magnetics; cross-section measurements; vacuum systems and techniques; bell- lightning; and design and engineering. Separate abstracts were prepared for the 11 sections. (B.O.G.)

A number of metals, carbides, nitrides, oxides, borides, and uranium gulfides are briefly evaluated concerning their possible applications as advanced nuclear rocket materials. (R.J.S.)

Information of interest to analytical chemists is presented in a report containing both positive and negative results obtained in a total of 58,467 determinations. The data and information are presented in sections concernlng the work of the shift laboratory, special analysis laboratory, spectral analytical group, analytical development group, quality control and standards laboratory, and analytical service for EOCR. Details of methods added to the ICPP analytical manual, and to the ICPP analytical radiochemlcal manual are included. (J.R.D.)

S>A program will be required for controlling the wall temperature of a pot calciner during calcination in order to prevent an excessive temperature rise from internal heat generation while assuring complete calcination of the cake at 1650 deg F. A linear approximation to a pot wall temperature program indicates that this can be accomplished by holding the wall temperature at 1650 deg for 0.8 to 1.0 hrs and then cooling the wall at rates dependent upon the cake internal heat generation rate and average thermal conductivity. A similar study indicates that if it is necessary to reheat the cake for complete calcination, the wall heating time must be limited to prevent excessive temperature rise in the cake. Reheating times are also dependent upon the cake internal heat generation and thermal conductivity. (auth)

A survey was made of methods potentially useful for the determination of the oxygen to metal ratio in mixed oxides of uranium and plutonium. A gravimetric method was selected as being the most promising for adaptation in a short period of time. Development of the technique resulted in a reliable method which meets the requirements for unirradiated mixed oxide fuel samples. The method, based upon an equilibrium weight at 700 deg C in dry hydrogen, was shown to be capable of measurement of O/(Pu + U) ratios in 20% PuO/sub 2/--80% UO/sub 2/ pellets with a standard deviation of plus or minus 0.001. (auth)

Progress is reported on research directed toward. the development of adhesives, which are compatible with explosives; the measurement of nuclear properties of polonium isotopes; residue adsorption; separation and purification of isotopes; thermal diffusion theory analyses; emission strength analyses for neutron sources; and krypton-85 counting methods development. (B.O.G.)

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This report details activities of the N-Reactor Research and Engineering Operation Department for the month of May 1965.

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