Spectroscopic investigation of the formation of PuO{sub 2}Cl{sup +} and PuO{sub 2}Cl{sub 2} in NaCl solutions and application for natural brine solutions

Journal Article · Fri Oct 01 04:00:00 EDT 1999 · Geochimica et Cosmochimica Acta

DOI:https://doi.org/10.1016/S0016-7037(99)00275-6· OSTI ID:20003988

Runde, W; Reilly, S D; Neu, M P

The chloride complexation of the PuO{sub 2}{sup 2+} ion has been studied in acidic NaCl solutions with electrolyte concentrations as high as 5 mol kg{sup {minus}1} at 23 C by using conventional absorption spectrophotometry. Plutonyl and its complexes have ionic strength-dependent molar absorptivities that were determined in NaClO{sub 4}, the first essential step in the quantitative analysis of chloride complexation. The distributions of species for the Pu complexes, PuO{sub 2}{sup 2+}, PuO{sub 2}Cl{sup +}, and PuO{sub 2}Cl{sub 2}{degree}, formed under the conditions investigated, were determined by peak-fitting of optical absorption spectra. The apparent stability constants of the Pu(VI) chloro complexes were calculated at each NaCl concentration. Specific ion-interaction theory parameters were determined for the plutonyl chloro complexes and the electrolyte constituents, then compared with the literature data. The calculated values for log {beta}{degree} were determined to be 0.23 {+-} 0.03 and {minus}1.7 {+-} 0.2 for the mono and bis chloro complexes, respectively. Spectra of Pu(VI) in brines representative of waters at the Waste Isolation Pilot Plant, the licensed nuclear waste repository in a salt formation at Carlsbad, NM, USA, were measured and modeled by using the thermodynamic data and ion interaction parameters were determined. In these brines, less than 10% of the total Pu(VI) concentration exists as the Pu(VI) aquo ion, whereas about 90% is present as Pu(VI) chloro complexes.

• Research Organization: Los Alamos National Lab., NM (US)
• Sponsoring Organization: US Department of Energy
• OSTI ID: 20003988
• Journal Information: Geochimica et Cosmochimica Acta, Journal Name: Geochimica et Cosmochimica Acta Journal Issue: 19-20 Vol. 63; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
54 ENVIRONMENTAL SCIENCES
BRINES
OXYCHLORIDES
PLUTONIUM COMPOUNDS
RADIONUCLIDE MIGRATION
STABILITY
WIPP