Plutonium Alloys Research Articles

X-ray method for measuring percentage of alpha in delta-stabilized plutonium alloys

A nondestructive, x-ray method for measuring the percentage of alpha plutonium in delta-stabilized plutonium alloys is described. The necessary theory for the method is developed, and the constant for the theoretical equation as applied to the Pu-Ga system is evaluated experimentally. The sources and magnitudes of errors in the measurement are discussed. The method is then proved by using standards based on micromixtures and mechanical micromixtures. Lastly, the limitation of the method and its extension to other systems are discussed.

X-Ray Fluorescence Spectrometric Determination of Rare Earths in Plutonium

Two methods were evaluated for determining rare earths in plutonium: (1) For the lighter rare earths ( Z≦66), or low concentrations of the heavier rare earths, an adjacent rare earth was added as a carrier and also as an internal standard, the rare earths were separated from plutonium by fluoride precipitation, and the measured intensity ratios for the sample and for solutions having known concentrations were compared. The Lβ1 x-rays were measured for the lighter rare earths and the Lα1 x rays for the remaining lanthanides. (2) For the heavier rare earths ( Z>66), the Lα1 x-ray intensities were measured from a nitric acid solution of the sample and compared to intensities obtained for solutions having known concentrations. The minimum concentrations that could be measured with a relative standard deviation no greater than 4% by the separation internal standard method varied from approximately 0.5% for lanthanum to 0.01% for lutetium. The direct measurement of x-ray intensity was much less sensitive. Applicability of the methods was shown by successful analyses of plutonium alloys containing dysprosium, thulium, or lutetium.

Injection Casting Aluminum-10 Wt% Plutonium Fuel Elements

Eight hundred fifty aluminum-10 wt% plutonium alloy fuel rods containing ∼55 kg of plutonium were fabricated by an injection casting process and encapsulated in Zircaloy-2 tubing. Casting was accomplished by inserting one end of a 0.610-in.-i.d. × 42-in.-long Pyrex glass mold into the molten alloy and then evacuating the mold. The diameter of the cast rods was 0.600 in. ± 0.001 in. with an average length of 38 in. Each element contained two or more of the fuel rods, totaling 47.75 in. in length. Unheated Pyrex molds produced higher quality castings than 1) unheated mild steel molds, 2) heated Pyrex molds, or 3) heated mild steel molds. Plutonium melt homogeneity was significantly improved by changing from intermittent melt stirring to continuous melt stirring prior to casting.

Fluid Flow of Liquid Plutonium Alloys in an Oscillating-Cup Viscosimeter

An oscillating-cup viscosimeter was utilized to measure the viscosity of three low-melting plutonium alloys. The derived relationship for the viscosity calculation was confirmed by measurements on standard viscosity oils and on liquid metals which covered wide ranges of viscosities. Abnormal behavior was detected for the three plutonium alloys. When the period of oscillation was greater than 11.0 sec for the three plutonium alloys, the logarithmic decrement passed through a maximum, then decreased as the temperature decreased; at the same time the period of oscillation increased greatly. When the period of oscillation was 2.7 sec, the plutonium alloys behaved normally but showed very large viscosities, which approached 25 cP. The cause of the anomalous behavior was not determined but indicated possible viscoelastic or non-Newtonian behavior.

Diffusion in stabilized delta plutonium, I. Gallium

Iterdiffusion coefficients were measured on fcc lowgallium (3.0 and 7.9 at %) plutonium alloy couples annealed between 350 and 517 °C. Concentration-penetration data obtained with an electron microprobe analyzer were fitted by a least-squares technique to give the following Arrhenius relationship D ̃ = 1.3exp [−37 350 cal/RT] cm 2/sec.

Characteristics of the Aerosol Produced from Burning Sodium and Plutonium

Safety analysis of sodium-cooled plutonium-fueled fast reactor plants must be concerned with the possibility of fires involving these materials. Design of an air cleaning system for such a facility requires basic data defining the aerosol characteristics of sodium and plutonium released during a fire. Size characteristics of the aersol produced during sodium and plutonium fires were determined for different atmospheres ranging from 20.8% oxygen, 79.2% nitrogen to 100% nitrogen. The aerosol produced by burning gram quantities of sodium was compared with that produced by a fire involving 600 lb of sodium. Sodium aerosol count median diameter ranged from 0.07 to 1.09 µ and was independent of oxygen concentration. Small and large scale fires produced an aerosol with comparable size characteristics. Plutonium aerosol count median diameter ranged from 0.02 to 0.09 µ and was also independent of oxygen concentration. When plutonium alloy was burned under reduced oxygen conditions, the fraction airborne ranged from 2. × 10-7 to 4. × 10-6. Fires involving plutonium alloy and sodium together produced airborne plutonium-sodium ratios ranging from 0.34 to 0.008%.

Effect of Oxygen and Nitrogen in Tantalum on its Resistance to Corrosion by Liquid Plutonium Alloys

The effect of oxygen and nitrogen content of tantalum on its resistance to corrosion by molten plutonium-cerium-cobalt alloys was investigated. The impurity content of the tantalum ranged from 100-...

The kinetics of the α /ah β transformations in some dilute plutonium alloys

An investigation has been made of the kinetics of the α /ah β transformations in unalloyed plutonium, and dilute plutonium alloys containing either neptunium or titanium. The solutes were chosen because titanium is known to stabilize the beta phase whereas neptunium raises the α /ah β transition temperature and thus may be considered to stabilize the alpha phase. The results show that relative to unalloyed plutonium, titanium retards the β → α transformation but accelerates the α → β transition. In contrast neptunium has exactly the opposite effect. It appears therefore that the greater the driving force for the transformation the faster the rate of reaction.

Direct-Contact Core Systems

This study considers a fast-reactor concept in which the recirculating molten plutonium alloy fuel is externally cooled by direct contact with an immiscible coolant fluid. An example of one such design is given using sodium as the coolant and Pu/Co/Ce ternary as the fuel. Operational characteristics are discussed showing the self-regulating features of the system. Some fission-product-removal mechanisms are considered together with their effect on core life and system safety. The principal problem areas are fuel pumping, phase separation, and containment-materials compatability.

The effect of self-irradiation on the lattice constants of alloys of plutonium in alpha-uranium

The effect of self-irradiation on the lattice constants of alloys of plutonium in alpha-uranium

The mechanical properties of plutonium-aluminium and plutonium-cerium alloys

An investigation has been made of the mechanical properties of Pu-Al and Pu-Ce alloys in the range 0 at % solute to the upper limit of the delta stabilised field. The compositional dependence of the UTS, flow stress, elongation, reduction in area, Young's Modulus, density and hardness was determined for each series of alloys. From a consideration of the above data new positions for the (α + δ)/δ phase boundary have been proposed for the two alloy systems. The main factors influencing the solution hardening of deltastabilised plutonium alloys are also discussed in relation to the results obtained in this investigation.

Room temperature lattice constants of alloys of plutonium in alpha-uranium

Lattice constants of solid solutions of plutonium in alpha-uranium have been measured at room temperature, 25° ± 2° C, by the Debye-Scherrer method, from samples prepared by furnace cooling from 400° C. The, lattice constants a 0 and c 0 were found to increase and b 0 to decrease with increased plutonium content, until a concentration of about 15 wt % Pu was reached. The lattice constants of the 15 wt %, Pu alloy were: a 0 = 2.8625 A ̊ , b 0 = 5.8562 A ̊ , c 0 = 4.9631 A ̊ .

Atmospheric corrosion tests of several delta phase alloys of plutonium

A study of the oxidation of delta-phase, binary plutonium alloys containing small additions of aluminum, cerium, hafnium, zinc and zirconium has been conducted. The oxidation rates at 75° C in moist air are all lower than the oxidation rate of unalloyed plutonium under the same conditions. The results do not appear to be in accord with the simple theory of the influence of solute additions on the oxidation rate as proposed by Wagner and Hauffe. A size rule was suggested for deciding a priori whether a solid-solution miscibility gap between oxide phases might occur. This rule was only partially successful in predicting which oxide phases would be observed to form separate layers. It is interesting that the zirconium and hafnium alloys were found to form ZrO 2 and HfO 2 as separate phases in the oxide layer. These separate oxide phases are to be expected on the basis of the size-factor rule discussed above. There is no evidence, however, that Al 2O 3 or ZnO, in which smaller metal-oxygen distances occur, were present as separate phases in the oxidation products. For thermodynamic reasons, ZnO should not appear in the products. The special reasons that Ce 2O 3 and Al 2O 3 might not be detected have been discussed. The analyses of Wagner concerned with the formation of single or duplex oxide films have been discussed and it is shown that the formation of HfO 2 and ZrO 2 as well as Al 2O 3 and Ce 2O 3 should occur. The apparent reduction in rates can be rationally interpreted on this basis.

The effects of irradiation on solids

A short survey is given of the reports on the effects of radiation on solids that were given at the Second International Conference on the Peaceful Use of Atomic Energy (Geneva, 1958). Consideration is given to the experimental work devoted to quantitative estimates of radiation damage, and also to questions of the action of neutron radiation on fissionable materials (uranium, plutonium, and certain alloys of these metals). New data are presented on the effect of very high burnups (up to 2 atom per cent) on the size and shape of units made of uranium and its alloys, and also on the increase of volume (swelling) of uranium units under the action of radiation. Detailed attention is also given to data on studies of uranium alloy with 9 per cent of molybdenum by weight, and also of pure uranium, which give evidence of high mobility of the atoms in uranium and its alloys under irradiation. Data are presented on the effects of temperature and of radiation dosage, and also on a number of other factors, on the mechanical properties of steels and other construction materials. Results are presented from studies of the effects of irradiation on nonmetallic materials: BeO, UO2-BeO and UO2ThO2 mixtures, graphite, and so on.

The determination of americium in Plutonium Alloy fuels for fast reactors

Summary For the determination of americium in fast-reactor plutonium fuels, a method is required which is quantitative and which gives a product free of either alpha or gamma contaminants, since either alpha or gamma counting may be used for the detection of Am241. In the present method, americium, plutonium, and the rare-earth fission products are precipitated as hydroxides from an HCl solution of the fuel sample, after the addition of lanthanum as a carrier. Ceric sulfate is added to the acidified hydroxide precipitate to oxidize plutonium to the hexavalent state. The hexavalent plutonium remains in solution when americium and the rare-earth fluorides are precipitated. After the fluoride precipitate is dissolved in HNO3 and H3BO3, a second hydroxide precipitation is performed to remove fluoride. This precipitate is dissolved in a small quantity of HNO3 and transferred to an ion-exchange column packed with Dowex 50-X4, 200- to 400-mesh resin. Americium and the rare-earth elements are eluted with 5 % NH4NO3 saturated with ethylenediaminetetra-acetic acid at a pH of 2.3. The americium is eluted after the yttrium and just prior to the elution of the europium fractions. In fresh samples (less than 2 days old), the americium may be contaminated with Eu156, but it is free of all other rare-earth elements, permitting alpha counting in a sample with low beta activity. Recovery of americium is better than 98 %, with less than 2 % plutonium alpha activity and with a gamma decontamination factor of 2 × 104. If the sample has aged sufficiently to allow the short-half-lived rare-earth elements to disappear, the americium may be determined by counting the gamma activity.

The chemical analysis of ternary alloys of plutonium with Molybdenum and Uranium

It is shown that the absorptiometric determination of molybdenum as thiocyanate may be used in the presence of plutonium. Molybdenum interferes with previously published methods for determining uranium and plutonium but conditions have been established for its complete removal by solvent extraction of the compound with a-benzoin oxime. The previous methods for uranium and plutonium are satisfactory when applied to the residual aqueous phase following this solvent extraction.

X-Ray Spectrographic Determination of Uranium and Plutonium in Aluminum and Other Reactor Fuel Materials

AbstractSeveral instrument modifications are described including a shop-built turret mount which provides four water-cooled sample compartments, each accommodating samples up to 1.75 inches in diameter by 1.75 inches long.Sensitivity for detection of the elements throughout the Periodic Chart is discussed for several counters.Uranium and plutonium have been determined up to 20 w/o in metallic samples of aluminum alloys with a precision of ± one per cent in less than three minutes counting time. The determination of uranium dioxide in cryolite involved powder samples and the use of an internal standard. Uranium dioxide dispersions in bismuth metal were very heterogeneous; they were dissolved and precipitated to provide homogeneous, powders which were analyzed by measuring the intensity ratio of uranium and bismuth fluorescence.X-ray fluorescence has been used to measure aluminum cladding thickness over plutonium alloy cores. Precision is discussed in terms of cladding thickness, aperture size, and counting time. Thickness of 11 w/o and 14 w/o plutonium-aluminum and enriched uranium-aluminum cores in reactor fuel plates has been measured by X-ray absorption in the range 0.010 to 0.030 inch with a sensitivity of ± 0.00025 inch.

Alloys of plutonium with rare earth metals

Alloys of plutonium with rare earth metals

Alloys of plutonium and americium with beryllium

Alloys of plutonium and americium with beryllium