Plutonium dioxide

Plutonium has a much shorter half-life than uranium (24.000 years for Pu-239 6,500 years for Pu-240). Plutonium is most toxic if it is inhaled. The radioactive decay that plutonium undergoes (alpha decay) is of little external consequence, since the alpha particles are blocked by human skin and travel only a few inches. If inhaled, however, the soft tissue of the lungs will suffer an internal dose of radiation. Particles may also enter the blood stream and irradiate other parts of the body. The safest way to handle plutonium is in its plutonium dioxide (PuOj) form because PuOj is virtually insoluble inside the human body, gi eatly reducing the risk of internal contamination. 

Figure 2. Partial pressures of vapor species versus composition of the substoichiometric plutonium dioxide phase at 1970 K.

Vapor Pressures and Vapor Compositions in Equilibrium with Hypostoichiometric Plutonium Dioxide at High Temperatures... 

Vapor pressures and vapor compositions in equilibrium with a hypostoichiometric plutonium dioxide condensed phase have been calculated for the temperature range 1500 I H 4000 K. Thermodynamic functions for the condensed phase and for each of the gaseous species were combined with an oxygen-potential model, which we extended from the solid into the liquid region to obtain the partial pressures of O2, 0, Pu, PuO and Pu02 as functions of temperature and of condensed phase composition. The calculated oxygen pressures increase rapidly as stoichiometry is approached. At least part of this increase is a consequence of the exclusion of Pu +... 

Thermodynamic Functions of the Condensed Phases. Tabulated thermodynamic functions for the condensed phases of plutonium dioxide and a detailed description of their calculation are given elsewhere (21). The AG (Pu02 c) is represented by the equation given in Table I. The AGf values were calculated using standard thermodynamic relations and the data given below. 

Table II. Important Transition Temperatures for the Plutonium Dioxide Condensed Phase...

Table III. Ionization Potentials (IP) of the Molecules and Atoms In Equilibrium with a Plutonium Dioxide Condensed Phase (1 eV molecule- - - 23.06 kcal mol- =...

Measurement of the 0/Pu ratio of the vapor in equilibrium with plutonium dioxide liquid. 

Green, D. W. Fink, J. K. Leibowitz, L. "Vapor Pressures- and Vapor Compositions in Equilibrium with Hypostoichiometric Uranium-Plutonium Dioxide at High Temperatures," presented at the 8th European Conference on Thermophysical Properties, Baden-Baden, September 27 - October 1, 1982 to be published in High Temperatures-High Pressures. 

Salt Processing of Impure Plutonium Dioxide to High-Purity Metal, U.S. DOE Report LA-9154-MS, Los Alamos National... 

Fluorination and Reduction. Until recently, plutonium dioxide from the calcination of plutonium peroxide was contacted with HF in a rotary hydrofluorinator. The reaction converted Pu02 to PuFt, according to the following equation ... 

Complete dissolution of plutonium residues, especially high temperature calcined plutonium dioxide contained in residues such as incinerator ash, continues to cause problems, despite continued research since the Manhattan Project (9). Methods to improve the Rocky Flats system include the use of additives (e.g., cerium) and electrochemistry, other solvents (HCl-SnCl2) as well as high-temperature fusion methods (10). High pressure dissolution, HF preleaching, fluorination, and other methods are being investigated. 

Felt, R.E. "A Pyrochemical Process for the Reduction of Plutonium Dioxide to Metal", Atlantic Richfield Hanford Co. Report ARH-1198, July 1969. 

Mullins, L.J. Christensen, D.C. Babcock, B.R. "Fused Salt Processing of Impure Plutonium Dioxide to High Purity Metal", Los Alamos Nat. Lab. Report LA-9154-MS also Symposium on Actinide Recovery from Waste and Low Grade Sources, ACS, New York City August 23-28, 1981 (in press). 

Knighton, J. B. Steunenberg, R. K., "Preparation of Metals By Magnesium Zinc Reduction, Part II, Reduction of Plutonium Dioxide," ANL-7059, Argonne National Laboratory, Argonne Illinois, June 1965. 

Another example of the use of carbon tetrachloride for chlorination is the conversion of plutonium dioxide to plutonium trichloride according to the reactions... 

The conversion of plutonium dioxide to plutonium trichloride has often been carried out by using phosgene (COCl2) instead of carbon tetrachloride or carbon and chlorine ... 

Plutonium tetrafluoride is prepared from plutonium dioxide by the following reaction at temperatures between 400 and 600 °C ... 

Plutonium compounds, 19 687-691 protection against, 19 702 Plutonium dioxide, 19 688—689 Plutonium fuel fabrication facilities, 17 547 Plutonium-gallium alloys, 19 683-684 Plutonium halides, 19 689-690 Plutonium hexafluoride, 19 689 Plutonium hydrides, 19 690 Plutonium ions... 

Plutonium (IV) oxide Pu + 20 —> PuO. Also known as plutonium dioxide. 

Plutonium combines with oxygen at high temperatures to form plutonium dioxide, Pu02, and other oxides. The dioxide also is formed in the presence of water vapor. Ignition of the metal in air at 1,000°C yields Pu02. 

The most studied non-stoichiometric system in actinide CaF2-structured compounds is the An-0 system all actinide dioxides (with the exception of Th02) present large departures from stoichiometry. Since uranium and plutonium dioxides (and their solid solutions) are employed as fuels in nuclear reactors, a very large effort has been dedicated to the study of their physical and physico-chemical properties. All these properties are affected by the oxygen composition of the compound. 

Matyunin, Yu. I., Alexeev, O. A. Ananina, T. N. 2001. Immobilization of plutonium dioxide into borobasalt, pyroxene and andradite compositions. In GLOBAL 2001 International Conference on Back End of the Fuel Cycle From Research to Solutions , Paris, CD-ROM. 

Haschke, J. M., Allen T. H. Morales, L. A. 2000. Reaction of plutonium dioxide with water Formation and properties of Pu02+x. Science, 237, 285-287. 

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