Dissolved Concentration Limits of Radioactive Elements

Technical Report · Fri Jun 20 00:00:00 EDT 2003

DOI:https://doi.org/10.2172/836527· OSTI ID:836527

Chen, Y.; Thomas, E. R.; Pearson, F. J.; Cloke, P. L.; Steinborn, T. L.; Brady, P. V.

The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, and measurements made in laboratory experiments and field work. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 radioactive elements (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium), which are important to calculated dose. Model outputs are mainly in the form of look-up tables plus one or more uncertainty terms. The rest are either in the form of distributions or single values. The results of this analysis are fundamental inputs for total system performance assessment to constrain the release of these elements from waste packages and the engineered barrier system. Solubilities of plutonium, neptunium, uranium, americium, actinium, thorium, protactinium, lead, and radium have been re-evaluated using the newly updated thermodynamic database (Data0.ymp.R2). For all of the actinides, identical modeling approaches and consistent environmental conditions were used to develop solubility models in this revision. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, activity coefficients, and selection of solubility controlling phase have been quantified or otherwise addressed. Moreover, a new blended plutonium solubility model has been developed in this revision, which gives a mean solubility that is three orders of magnitude lower than the plutonium solubility model used for the Total System Performance Assessment for the Site Recommendation. Two alternative neptunium solubility models have also been developed in this revision. The base-case models have been validated to the level of confidence required by their relative importance to the potential performance of the repository system. The plutonium and neptunium solubility models have been validated to a higher level of confidence than the rest.

• Research Organization: Yucca Mountain Project, Las Vegas, NV (United States)
• Sponsoring Organization: US Department of Energy (US)
• OSTI ID: 836527
• Report Number(s): ANL-WIS-MD-000010, Rev. 02; DOC.20030624.0003, DC No. 34715; TRN: US0500673
• Resource Relation: Other Information: PBD: 20 Jun 2003
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ACTINIUM
AMERICIUM
CESIUM
IODINE
NEPTUNIUM
PLUTONIUM
PROTACTINIUM
RADIUM
REACTION KINETICS
SOLUBILITY
STRONTIUM
TECHNETIUM
THERMODYNAMICS
THORIUM
URANIUM
GEOCHEMISTRY
LIMITING VALUES
CONCENTRATION RATIO
RADIOACTIVE WASTE DISPOSAL
CARBON
RADIONUCLIDE MIGRATION
CONTAINMENT SYSTEMS