Water activity is an important parameter needed to predict the solubility of hydrated salts in Hanford nuclear waste supernatants. A number of models available in the scientific literature predict water activity from electrolyte solution composition. The Cisternas-Lam model is one of those models and has several advantages for nuclear waste application. One advantage is that it has a single electrolyte specific parameter that is temperature independent. Thus, this parameter can be determined from very limited data and extrapolated widely. The Cisternas-Lam model has five coefficients that are used for all aqueous electrolytes. The present study aims to determine if there is a substantial improvement in making all six coefficients electrolyte specific. The Cisternas-Lam model was fit to data for six major electrolytes in Hanford nuclear waste supernatants. The model was first fit to all data to determine the five global coefficients, when they were held constant for all electrolytes it yielded a substantially better fit. Subsequently, the model was fit to each electrolyte dataset separately, where all six coefficients were allowed to be electrolyte specific. Treating all six coefficients as electrolyte specific did not make sufficient difference, given the complexity of applying the electrolyte specific parameters to multi-solute systems. Revisedmore » water specific parameters, optimized to the electrolytes relevant to Hanford waste, are also reported.« less
The Used Fuel Disposition (UFD) Campaign within DOE-NE is evaluating storage and disposal options for a range of waste forms and a range of geologic environments. For each waste form and geologic environment combination, there are multiple options for repository conceptual design. The Disposal Systems Evaluation Framework (DSEF) is being developed to formalize the development and documentation of options for each waste form and environment combination. The DSEF is being implemented in two parts. One part is an Excel workbook with multiple sheets. This workbook is designed to be user friendly, such that anyone within the UFD Campaign can use it as a guide to develop and document repository conceptual designs that respect thermal, geometric, and other constraints. The other part is an Access relational database file that will be centrally maintained to document the ensemble of conceptual designs developed with individual implementations of the Excel workbook. The DSEF Excel workbook includes sheets for waste form, environment, geometric constraints, engineered barrier system (EBS) design, thermal, performance assessment (PA), materials, cost, and fuel cycle system impacts. Each of these sheets guides the user through the process of developing internally consistent design options, and documenting the thought process. The sheets interact with each other to transfer information and identify inconsistencies to the user. In some cases, the sheets are stand-alone, and in other cases (such as PA), the sheets refer the user to another tool, with the user being responsible to transfer summary results into the DSEF sheet. Finally, the DSEF includes three top-level sheets: inputs & results, interface parameters, and knowledge management (references). These sheets enable users and reviewers to see the overall picture on only a few summary sheets, while developing the design option systematically using the detailed sheets. The DSEF Access relational database file collects the key inputs, results, and interface parameters from each Excel workbook implementation. The power of a relational database is available to sort and organize groups of designs, and to answer queries about what evaluations have been done in the UFD Campaign.
The US is developing a strategy for the disposition of surplus weapons-usable uranium-233 ({sup 233}U). The strategy (1) identifies the requirements for the disposition of surplus {sup 233}U; (2) identifies potential disposition options, including key issues to be resolved with each option; and (3) defines a road map that identifies future key decisions and actions. The disposition of weapons-usable fissile materials is part of a US international arms-control program for reduction of the number of nuclear weapons and the quantities of nuclear-weapons-usable materials worldwide. The disposition options ultimately lead to waste forms requiring some type of geological disposal. Major options are described herein.
ESF is a planned underground laboratory to conduct subsurface explortion and testing in support of site suitability determination and license application for a potential high-level nuclear waste repository at Yucca Mountain. ESF design includes a 7.6 m dia, 7.8 km long tunnel loop of two main access ramps from the surface down to a main drift along the conceptual repository horizon in a fractured, welded tuff (Topopah Spring member of Paintbrush Tuff). The use of water during excavation of the ESF is expected to have negligible effects on radionuclide release from waste packages, provided the volume of water lost to the geologic environment is limited to 7.4 m{sup 3}/m of linear excavation.
Samples of tuff aseptically collected from 10 locations in the Exploratory Shaft Facility at the site of the proposed high-level nuclear waste repository at Yucca Mountain, Nevada Test Site were analyzed for microbiological populations, activities, and factors limiting microbial activity. Radiotracer assays (C-14-labeled organic substrate mineralization), direct microscopic counts, and plate counts were used. Radiolabeled substrates were glucose, acetate, and glutamate. Radiotracer experiments were carried out with and without moisture and inorganic nutrient amendments to determine factors limiting to microbial activities. Nearly all samples showed the presence of microorganisms with the potential to mineralize organic substrates. Addition of inorganic nutrients stimulated activities in a small number of samples. The presence of viable microbial communities within the tuff has implications for transport of contaminants.
This paper delineates the major provisions and implications of Executive Order 12898, Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations. It also presents a brief background of environmental justice concerns in relation to Department of Energy (DOE) activities, and describes selected elements of the U.S. Department of Energy`s impletation of the order. It further describes accomplishments thus far achieved toward implementation, provides examples of approaches which may be taken in the field, and discusses future expectations.
Various mathematical formulations have been proposed for the treatment of model uncertainty. These formulations can be categorized as model-focused or prediction focused, according to whether the attention is directed towards the plausibility of the model hypotheses or to the accuracy of its predictions. In this paper we embrace the model-focused approach and propose a new tool for the quantitative analysis of the alternate models hypotheses, and for the evaluation of the probabilities representing the degree of belief on the validity of these hypotheses.
The purpose of this paper is to describe the initial reaction of the Electric Power Research Institute (EPRI) to the report produced by the National Academy of Sciences !NAS) Committee on the Technical Bases for Yucca Mountain Standards (the Committee)(1).
Before the Waste Isolation Pilot Plant (WIPP) is licensed for final disposal of transuranic (TRU) and transuranic mixed waste, the Department of Energy (DOE) must demonstrate compliance with a wide range of regulatory, environmental, safety, and design requirements. The DOE must submit an application for operation of the disposal facility, along with the supporting scientific, engineering, and environmental data. The principle tool for assuring that the applicable requirements are met, and that the application is approved by the regulator, is a comprehensive quality assurance program developed and implemented by the Carls-bad Area Office (CAO) of the DOE.
The uncertainty is a very important measure which can contribute to proper decision making. Another very important role of the uncertainty is that uncertainty is the measurable value which can be used as quality describing factor. Thus the uncertainty is very important for quality assurance of research process.
