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Title: Fundamental Thermodynamics of Actinide-Bearing Mineral Waste Forms

Abstract

The recent arms reduction treaties between the U.S. and Russia have resulted in inventories of plutonium in excess of current defense needs. Storage of this material poses significant, and unnecessary, risks of diversion, especially for Russia whose infrastructure for protecting these materials has been weakened since the collapse of the Soviet Union. Moreover, maintaining and protecting these materials in their current form is costly. The United States has about sixty metric tons of excess plutonium, half of which is high-purity weapon material. This high purity material will be converted into mixed oxide (MOX) fuel for use in nuclear reactors. The less pure excess plutonium does not meet the specifications for MOX fuel and will not be purified to meet the fuel specifications. Instead, it will be immobilized directly in a ceramic. The ceramic will be encased in a high level waste (HLW) glass monolith (i.e., the can-in-canister option) thus making a form that simulates the intrinsic security of spent nuclear fuel. The immobilized product will be placed in a HLW repository. To meet the repository requirements, the product must be shown to be durable for the intended storage time, the host matrix must be stable in the radiation environment, themore » solubility and leaching characteristics of the plutonium in the host material must be established, and optimum processing parameters must be determined for the entire compositional envelope of feed materials. In order to provide technically sound solutions to these issues, thermodynamic data are essential in developing an understanding of the chemistry and phase equilibria of the actinide-bearing mineral waste forms proposed as immobilization matrices. However, the relevant thermodynamic data (e.g., enthalpy, entropy, and heat capacity) for the ceramic forms are severely lacking and this information gap directly affects the Energy Department's ability to license the disposal matrices and methods. High-temperature solution calorimetry is one of the most powerful techniques, sometimes the only technique, for providing the fundamental thermodynamic data needed to establish optimum material fabrication parameters, and more importantly, understand and predict the behavior of the mineral materials in the environment. The purpose of this project is to experimentally determine the enthalpy of formation of actinide orthosilicates, the enthalpies of formation of actinide substituted zircon, zirconolite and pyrochlore, and develop an understanding of the bonding characteristics and stabilities of these materials.« less

Authors:
; ;
Publication Date:
Research Org.:
Los Alamos National Lab., Los Alamos, NM; Lawrence Livermore National Lab., Livermore, CA; University of California at Davis, Davis, California (US)
Sponsoring Org.:
USDOE Office of Environmental Management (EM) (US)
OSTI Identifier:
828524
Report Number(s):
EMSP-60118-1999
R&D Project: EMSP 60118; TRN: US0404011
DOE Contract Number:  
FG07-97ER45673
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1 Jun 1999
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 54 ENVIRONMENTAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACTINIDES; CERAMICS; ENTHALPY; FORMATION HEAT; MINERAL WASTES; NUCLEAR FUELS; PLUTONIUM; PYROCHLORE; RADIATIONS; REACTORS; SPECIFIC HEAT; THERMODYNAMICS; WASTES; WEAPONS; ZIRCON; ZIRCONOLITE

Citation Formats

Williamson, Mark A, Ebbinghaus, Bartley B, and Navrotsky, Alexandria. Fundamental Thermodynamics of Actinide-Bearing Mineral Waste Forms. United States: N. p., 1999. Web. doi:10.2172/828524.
Williamson, Mark A, Ebbinghaus, Bartley B, & Navrotsky, Alexandria. Fundamental Thermodynamics of Actinide-Bearing Mineral Waste Forms. United States. doi:10.2172/828524.
Williamson, Mark A, Ebbinghaus, Bartley B, and Navrotsky, Alexandria. Tue . "Fundamental Thermodynamics of Actinide-Bearing Mineral Waste Forms". United States. doi:10.2172/828524. https://www.osti.gov/servlets/purl/828524.
@article{osti_828524,
title = {Fundamental Thermodynamics of Actinide-Bearing Mineral Waste Forms},
author = {Williamson, Mark A and Ebbinghaus, Bartley B and Navrotsky, Alexandria},
abstractNote = {The recent arms reduction treaties between the U.S. and Russia have resulted in inventories of plutonium in excess of current defense needs. Storage of this material poses significant, and unnecessary, risks of diversion, especially for Russia whose infrastructure for protecting these materials has been weakened since the collapse of the Soviet Union. Moreover, maintaining and protecting these materials in their current form is costly. The United States has about sixty metric tons of excess plutonium, half of which is high-purity weapon material. This high purity material will be converted into mixed oxide (MOX) fuel for use in nuclear reactors. The less pure excess plutonium does not meet the specifications for MOX fuel and will not be purified to meet the fuel specifications. Instead, it will be immobilized directly in a ceramic. The ceramic will be encased in a high level waste (HLW) glass monolith (i.e., the can-in-canister option) thus making a form that simulates the intrinsic security of spent nuclear fuel. The immobilized product will be placed in a HLW repository. To meet the repository requirements, the product must be shown to be durable for the intended storage time, the host matrix must be stable in the radiation environment, the solubility and leaching characteristics of the plutonium in the host material must be established, and optimum processing parameters must be determined for the entire compositional envelope of feed materials. In order to provide technically sound solutions to these issues, thermodynamic data are essential in developing an understanding of the chemistry and phase equilibria of the actinide-bearing mineral waste forms proposed as immobilization matrices. However, the relevant thermodynamic data (e.g., enthalpy, entropy, and heat capacity) for the ceramic forms are severely lacking and this information gap directly affects the Energy Department's ability to license the disposal matrices and methods. High-temperature solution calorimetry is one of the most powerful techniques, sometimes the only technique, for providing the fundamental thermodynamic data needed to establish optimum material fabrication parameters, and more importantly, understand and predict the behavior of the mineral materials in the environment. The purpose of this project is to experimentally determine the enthalpy of formation of actinide orthosilicates, the enthalpies of formation of actinide substituted zircon, zirconolite and pyrochlore, and develop an understanding of the bonding characteristics and stabilities of these materials.},
doi = {10.2172/828524},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1999},
month = {6}
}

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