Plutonium oxide

A variant of the HWR is the Eugen reactor developed by Japan. This reactor is heavy water-moderated but lightwater-cooled. It is fueled by mixed uranium—plutonium oxides. 

The corrosion behavior of plutonium metal has been summarized (60,61). a-Plutonium oxidizes very slowly in dry air, typically <10 mm/yr. The rate is accelerated by water vapor. Thus, a bright metal surface tarnishes rapidly in normal environments and a powdery surface soon forms. Eventually green PUO2 [12059-95-9] covers the surface. Plutonium is similar to uranium with respect to corrosion characteristics. The stabilization of 5-Pu confers substantial corrosion resistance to Pu in the same way that stabilization of y-U yields a more corrosion-resistant metal. The reaction of Pu metal with Hquid water produces both oxides and oxide-hydrides (62). The reaction with water vapor above 100°C also produces oxides and hydride (63). 

Only slightly less accurate ( 0.3—0.5%) and more versatile in scale are other titration techniques. Plutonium maybe oxidized in aqueous solution to PuO " 2 using AgO, and then reduced to Pu" " by a known excess of Fe", which is back-titrated with Ce" ". Pu" " may be titrated complexometricaHy with EDTA and a colorimetric indicator such as Arsenazo(I), even in the presence of a large excess of UO " 2- Solution spectrophotometry (Figs. 4 and 5) can be utilized if the plutonium oxidation state is known or controlled. The spectrophotometric method is very sensitive if a colored complex such as Arsenazo(III) is used. Analytically usehil absorption maxima and molar absorption coefficients ( s) are given in Table 10. Laser photoacoustic spectroscopy has been developed for both elemental analysis and speciation (oxidation state) at concentrations of lO " — 10 M (118). Chemical extraction can also be used to enhance this technique. 

Plutonium oxidation state Wavelength maximum, nm Molar ah sorptivities, L/(molcm) ... 

There are numerous complex (ternary and quaternary) plutonium oxides. Their properties have been reviewed (30). Plutonium oxidizes readily to Pu(VI) from binary oxides to complex oxides such as Ba PuO. The best way to oxidize Pu to Pu(VII) is to prepare complex oxides such as Li PuO from Li20 and PUO2 iu flowing oxygen (85). 

Ce02, Cm203, Tm203, Pu02. The radiation hazard and the costs involved eliminated all candidates but a 20% concn of Pu-238 or plutonium oxide... 

Figure 4. Plutonium oxide (2.77 micrograms) weighed on September 10, 1942. It is shown on a platinum weighing boat magnified approximately 40-fold. The Pu oxide appears as a crusty deposit (indicated by the arrow) near the end of the platinum weighing boat, which is held with forceps that grip a small handle.

Equations for the Standard Free Energy of Formation and Partial Molar Free Energies of Atomic Oxygen for Plutonium Oxides (1600-2150 K), cal/mol... 

Thermodynamic Functions of the Gases. To apply Eqs. (1-10), the free energies of formation, Ag , for all gaseous species as a function of temperature are required. Tabulated data were fit by a least-squares procedure to derive an analytical equation for AG° of each vapor species. For the plutonium oxide vapor species, the data calculated from spectroscopic data (3 ) were used for 0(g) and 02(g), the JANAF data (.5) were used and for Pu(g), data from the compilation of Oetting et al. (6) were used. The coefficients of the equations for AG° of the gaseous species are included in Table I. 

The uncertainties in the condensed-phase thermodynamic functions arise from (1) the possible existence of a solid-solid phase transition in the temperature range 2160 to 2370 K and (2) the uncertainty in the estimated value of the liquid heat capacity which is on the order of 40%. While these uncertainties affect the partial pressures of plutonium oxides by a factor of 10 at 4000 K, they are not limiting because, at that temperature, the total pressure is due essentially entirely to O2 and 0. 

A second source of plutonium, dispersed more locally, is liquid effluent from fuel reprocessing facilities. One such is the fuel reprocessing plant at Windscale, Cumbria in the United Kingdom where liquid waste is released to the Irish Sea(6). Chemical analysis of this effluent shows that about one percent or less of the plutonium is in an oxidized form before it contacts the marine water(7). Approximately 95 percent of the plutonium rapidly adsorbs to particulate matter after discharge and deposits on the seabed while 5 percent is removed from the area as a soluble component ). Because this source provided concentrations that were readily detected, pioneering field research into plutonium oxidation states in the marine environment was conducted at this location. 

The Los Alamos MPL can accept either plutonium nitrate solution or plutonium oxide as feed. If the feed is the nitrate solution, then the process steps are precipitation of... 

Impure plutonium oxide residues are dissolved in 12M HN03-0.1M HF under refluxing conditions, and then the plutonium is recovered and purified by anion exchange. Plutonium is leached from other residues, such as metal and glass, and is also purified by anion exchange. The purified plutonium eluate from the anion exchange process is precipitated with hydrogen peroxide. The plutonium peroxide is calcined to the oxide, and the plutonium oxide is fluorinated. The plutonium tetrafluoride is finally reduced to the metal with calcium. 

Plutonium Oxide Dissolution. All four sites dissolve impure PuO, residues in concentrated HND3 (10 to 14M) containing HF (<0.3M). Whereas material calcined at temperatures of... 

Colvin, C. A. Quantitative Determination of Plutonium Oxidation States in Variable Nitric Acid Solutions for Control Laboratories—Spectrophotometric, U.S. AEC Report RL-SA-33, General Electric Co., Richland, WA, 1965. 

Direct Oxide Reduction. Implementation of the DOR process into production Ts currently underway. Plutonium oxide from foundry operations, hydriding, and other sources is calcined in... 

Standifer, R. L. "Conversion of Plutonium Oxide to Plutonium Tetrafluoride with Fluorine in a Fluid Bed Reactor -Part I, Development Studies," U.S. AEC Rept. RFP-1889, Dow Chemical Company, Golden, Colorado, August 23, 1972. 

The following pages will describe several examples of pyrochemical processing as applied to the recycle of plutonium, and will briefly review the fundamental chemistry of these processes. We shall review the conversion of plutonium oxide to plutonium metal by the direct oxide reduction process (DOR),the removal of americium from metallic plutonium by molten salt extraction (MSE), and the purification of metallic... 

We can control the plutonium oxidation rate by reacting molten ZnCl2 salt with solid plutonium metal. 

Plutonium in solution is a function of six variables. The first two of these variables may be selected almost at pleasure. If plutonium oxidation number N and acidity are selected, the... 

Work has also been conducted that involved the investigation, via infrared spectroscopy, of matrix-isolated, plutonium oxides (40), with the appropriate precautions being taken because of the toxicity of plutonium and its compounds. A sputtering technique was used to vaporize the metal. The IR spectra of PuO and PUO2 in both Ar and Kr matrices were identified, with the observed frequencies for the latter (794.25 and 786.80 cm", respectively) assigned to the stretchingmode of Pu 02. Normal-coordinate analysis of the PUO2 isotopomers, Pu 02, Pu 02, and Pu 0 0 in Ar showed that the molecule is linear. The PuO molecule was observed in multiple sites in Ar matrices, but not in Kr, with Pu 0 at 822.28 cm" in the most stable, Ar site, and at 817.27 cm" in Kr. No evidence for PuOa was observed. 

Breuer F, Clemente GF, Strambi E, et al. 1980. A case of internal contamination with plutonium oxide. 

Stanley JA, Edison AF, Mewhinney JA. 1982. Distribution, retention and dosimetry of plutonium and americium in the rat, dog and monkey after inhalation of an industrial-mixed uranium and plutonium oxide aerosol. Health Phys 43(4) 521-530. 

Binary plutonium halides, 79 689 Binary plutonium oxide, 79 688 Binary polymer blends, 20 330-334, 343. See also Binary heterogeneous polymer blends... 

Plutonium nitride, 19 691 Plutonium oxalates, 19 691 Plutonium(IV) oxide, 19 669 Plutonium oxides, 19 688-689 Plutonium oxyhalides, 19 689-690 Plutonium pnictides, 19 691 Plutonium-producing reactors, storage of radioactive waste from, 25 855 Plutonium radioisotopes, 21 319 Plutonium refractory compounds, 19 687 Plutonium reprocessing plants, 19 686 Plutonium silicides, 19 690-691 Plutonium solutions, self-radiolysis of, 19 694... 

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