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Thermal Stabilization FY 1999 blend plan

Description: This Blend Plan documents the alternate feed material items for the thermal stabilization process that will be used in place of the metal items that were originally planned to be processed. Problems with resolution of the safety basis for the metal items resulted in the decision to run material that already had an established safety basis. Various in process and scrap recovery items stored in gloveboxes, plutonium oxide and plutonium oxide mixed with uranium oxide stored in 2736-Z vaults will be processed through the stabilization furnaces until the safety basis for the metal items has been resolved. The purpose of thermal stabilization is to heat the material to 1000 degrees Celsius to drive off all volatile materials and leave the plutonium and/or uranium as oxides. The stabilized material will be sampled to determine the Loss On Ignition (LOI). The stabilized material must meet LOI of less than 0.5% to be acceptable for storage under DOE-STD-3013-94 specifications. Out of specification material will be recycled through the furnaces until the LOI limits are met.
Date: February 23, 1999
Creator: RISENMAY, H.R.

THREE-DIMENSIONAL STROCHASTIC ROCK-PROPERTY AND UNCERTAINTY MODELS FOR YUCCA MOUNTAIN, NEVADA

Description: Licensing of Yucca Mountain as a geologic disposal site for high-level nuclear waste will require quantitative predictions of the waste-isolation performance of the rocks that form Yucca Mountain and of the engineered barrier system for an extended period of time into the future. These predictions will require the use of numerical modeling in an attempt to capture the essence of highly complex physical processes, such as ground-water flow and the transport of potential radionuclide contaminants under both unsaturated and saturated conditions. Additional numerical modeling will be required to demonstrate that a mined geologic repository can be constructed safely within the rocks of Yucca Mountain, and that the underground openings will remain stable in the longer term when affected by the thermal pulse of the emplaced waste forms. A fundamental principle involved in the numerical representation of real-world physical processes is that the properties of the modeled domain that are important to that representation must be known ''exhaustively''. Standard procedure in virtually all numerical physical-process modeling is to discretize the model volume into a (large) number of individual elements or grid nodes, assign the necessary attributes to each element or node, and then apply one or more sets of mathematical expressions that are believed to represent the operation of the physical processes under investigation, given some set of external boundary and initial conditions. Because each element or node within the model domain must be assigned a set of properties to represent the variables within the numerical approximation of the process, those properties must be known at each relevant point in space. characterization of a geologic site, such as at Yucca Mountain. Because descriptive characterization is limited both by access (particularly to the subsurface) and by the availability of resources, that description is necessarily incomplete. Therefore, the exhaustive description of a site ...
Date: February 23, 1998
Creator: MCKENNA, CHRISTOPHER A. RAUTMAN AND SEAN A.