Inactive UO/sub 2/ oxidizes at 180 deg C by tbe formation of a tetragonal oxide (U/sub 3/O/sub 7/), which is unsthble, on heating above 300 deg C. The U/sub 3/C/sub 7/ in compositions below UO/sub 2.25/ reacts with UO/sub 2/ to form UC/sub 2+x/ and U/sub 4/O/sub 9/. At compositions above UO/sub 2.25/, the tetragomal phase is stable to 600 deg C. In the homogenized condition, both U/ sub 3/O/sub 7/ and U/sub 4/O/sub 9/ are n-type conductors, while UO/sub 2+x/ is p- type. The solubility limit of O in UO/sub 2/, as determimed by x-ray diffraction data and electrical measurements, is UO/sub 2.08/ at 25 and 200 deg C, UO/sub 2.11/ at 400 deg C, UO/sub 2.17/at 600 deg C, and UO/sub 2.20/ above 700 deg C. The active UO/sub 2/ oxidation product retains the cubic symmetry of UO/sub 2/ up to the composition UO/sub 2.40/ and is stable to 600 deg C in vacuum. The structural behavior of the active oxide in this composition range is significantly different from that of the inactive oxide. (auth)

A Darex flowsheet is presented wherein dissolution of stainiess steel- type fuel elements in dilute aqua regia, stripping of chloride from spent dissolver solution, adjustment of stripper product composition and rectification of HNO/sub 3/ --H/sub 2/O vapors are accomplished in a completely continuous relatively simple loop process. Product from the loop needs only dilution with water to be made suitable as feed for a solvent extraction processing plant. The proposed scheme differs from earlier concepts. A continuous, pot dissolver (well- mixed liquid phase) is utilized rather than a trickle type dissolver. A strip vapor slightly lower in HNO/sub 3/ concentration than the azeotrope is used. A feed adjustment tank serves not only to recover HNO/sbu 3/ --H/sub 2/O vapor, but also to dehydrate any silica present and to adjust the product composition such that upon water addition the material is ready for feed to solvent extraction. In most previous concepts, separate, batchwise feed adjustment was contemplated. (auth)

The feasftbility of using gamma -ray attenuation techniques was demonstrated in determining the density and homogeneity of slurries circulating at 300 deg C. The method appears to have general utility in the engineering studies of slurry because the equipment is mounted externally and does not interfere with the system under investigation. Two types of detector systems were evaluated for routine service. The decimal counter-recorder system was found more adaptable for rugged operations, whereas the single channel analyzer was fouW to be more accurate and flexible. (auth)

Tests using a Westinghouse 400A canned motor circulating pump with various motor to impeller seal configurations are described. A configuration was found which allows very low flow rates and increases pump life. (T.R.H.)

Molten salts provide the basis of a new family of liquid fuel power reactors. The range of solubility of uranium and thorium compounds makes the system flexible, and allows the consideration of a variety of reactors. Suitable salt mixtures have meltirg points in the 85O to 95O deg F range and will probably prove to be sufficiently compatible with known alloys and to provide lorg-lived components, if the temperature is kept below 13OO deg F. Thus the salt systems naturally tend to operate in a temperature region suitable for modern steam plants and achieve these temperatures in unpressurized systems. Some economic and other considerations are made. (T.R.H.)

Examination of corrosion specimens from the 948 hour slurry blanket mock- up Run SM-3 lndicated generally low attack rates on type 347 stainless steel, titanium -75A, and Zircaloy-2. The upstream coupon of the array, of type 347 stainless steel, suffered moderate but more severe attack. Coupons of SA-212 grade B carbon steel were severely attacked. No stress corrosion cracking was noted on samples, placed in the pressurizer, of types 347 and AM 350 stainless steels, titanium aluminum--vanadium alloy, or Zircaloy-2. (auth)

A series of explosions, estimated at five, occurred over a period of ten seconds within the continuous dissolver pilot plant, of the Fluoride Volatility Project on May 15, 1957. The explosive reactions occurred in the dissolver vessels as a result of violent chemical reactions between uranium and an interhalogen mixture. Just what the conditions were which triggered the explosions, have not been definitely established. Nevertheless, based upon the evidence which has been collected, several possible explanations, listed according to probability, are presented. A number of recommendations are included to be followed before operation of the pilot plant is resumed. These recommendations relate to additional laboratory research, equipment design, facility design, and use of a review committee. Safety rules for handling BrF/ sub 3/, BrF/sub 5/, ClF/sub 3/, and Br/sub 2/ are appended. (C.H.)

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The most important variable in water quality on the uniform corrosion of Al was the pH. Solutions of distilled water containing phosphate ions and citrate ions were the only media which showed a definite specific ion effect. Phosphate inhibited the corrosion and citrate increased it. Oxalate ions appeared to increase corrosion, but the effect is not definitely demonstrated by the data. Corrosion was dependent only on pH in tap water, reactor process water, distilled water, and distilled water containing up to 100 ppm of chloride, nitrate, sulfate, bicarbonate, hydrogen peroxide, acetate, arsenate, silicate, dichromate, molybdate, and mixtures of these ions. Solutions of up to 10,000 ppm chloride in distilled water showed no specific ion effect upon uniform Al corrosion. The effects of 0 to 10 ppm of dichromate and phosphate ions were investigated over the range pH 4 to pH 7. Phosphate at 10 ppm inhibited corrosion in solutions containing up to 2 ppm of dichromate, but at 10 ppm dichromate the phosphate does not appear to inhibit corrosion. Also at 10 ppm dichromate, the effect of pH is diminished over the range pH 4 to pH 7. Corrosion rates varied with the flow rates of the test solutions at …

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