Vapor pressures and vapor compositions in equilibrium with hypostoichiometric plutonium dioxide at high temperatures

Journal Article · Sat Jan 01 04:00:00 EST 1983 · ACS Symp. Ser.; (United States)

DOI:https://doi.org/10.1021/bk-1983-0216.ch009· OSTI ID:6011086

Green, D W; Fink, J K; Leibowitz, L

Vapor pressures and vapor compositions in equilibrium with a hypostoichiometric plutonium dioxide condensed phase have been calculated for the temperature range 1500 less than or equal to T less than or equal to 4000 K. Thermodynamic functions for the condensed phase and for each of the gaseous species were combined with an oxygen-potential model, which has been extended from the solid into the liquid region to obtain the partial pressures of O/sub 2/, and O, Pu, PuO and PuO/sub 2/ 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/sup 6 +/ from the oxygen-potential model. No reliable method was found to estimate the importance of this ion, whose existence has not been established in the oxide system and whose effects might be expected to increase greatly with temperature, similar to the effects due to U/sup 6 +/ in the uranium/oxygen system. As a result of large oxygen potentials at high temperatures, extremely high total pressures that produced unreasonably high vapor densities were calculated. Results were limited to temperatures below 4000 K and oxygen-to-metal ratios of 1.994 to 1.70. These calculations show that the vapor in equilibrium with hypostoichiometric plutonium dioxide is poorly approximated as PuO/sub 2/ for most of the temperature and composition range of interest. The limitations of this approach and the implications of these calculations for the technologically important (U,Pu)O/sub 2-x/ system are also discussed. 43 references, 4 figures, 5 tables.

• Research Organization: Argonne National Lab., IL
• OSTI ID: 6011086
• Journal Information: ACS Symp. Ser.; (United States), Journal Name: ACS Symp. Ser.; (United States) Vol. 216; ISSN ACSMC
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPOUNDS
CHALCOGENIDES
CHEMICAL COMPOSITION
DATA
EXPERIMENTAL DATA
FLUIDS
GASES
INFORMATION
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PLUTONIUM COMPOUNDS
PLUTONIUM DIOXIDE
PLUTONIUM OXIDES
TEMPERATURE EFFECTS
THERMODYNAMIC PROPERTIES
TRANSURANIUM COMPOUNDS
VAPOR PRESSURE
VAPORS
VERY HIGH TEMPERATURE