Author: Judith B. MoodyPublisher:
ISBN:
Category : Radioactive waste disposal in rivers, lakes, etc
Languages : en
Pages : 80
Book Description
Radionuclide Migration/retardation
Author: Judith B. MoodyPublisher:
ISBN:
Category : Radioactive waste disposal in rivers, lakes, etc
Languages : en
Pages : 80
Book Description
I-129 Supplemental Information, Document Numbers 351-357
Author: Dana J. IsherwoodRadionuclide Migration/retardation
Author: Preliminary Report on Retardation Factors and Radionuclide Migration
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Available data on distribution coefficients for the biologically important radionuclides present in high-level waste were used to estimate retardation factors (K/sub f/) for a mass transport hydrologic model. The radionuclides were divided into 3 groups: fission products with no sorption (K/sub f/ = 1), fission products with sorption (K/sub f/ = 102), and the actinides and their daughter products (K/sub f/ = 104). Minimum and maximum values were assigned the latter two groups. Uncertainties as a function of time were estimated at +- an order of magnitude. 39 references, 5 tables.
Methods for Determining Radionuclide Retardation Factors
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
This report identifies a number of mechanisms that retard radionuclide migration, and describes the static and dynamic methods that are used to study such retardation phenomena. Both static and dynamic methods are needed for reliable safety assessments of underground nuclear-waste repositories. This report also evaluates the extent to which the two methods may be used to diagnose radionuclide migration through various types of geologic media, among them unconsolidated, crushed, intact, and fractured rocks. Adsorption is one mechanism that can control radionuclide concentrations in solution and therefore impede radionuclide migration. Other mechanisms that control a solution's radionuclide concentration and radionuclide migration are precipitation of hydroxides and oxides, oxidation-reduction reactions, and the formation of minerals that might include the radionuclide as a structural element. The retardation mechanisms mentioned above are controlled by such factors as surface area, cation exchange capacity, solution pH, chemical composition of the rock and of the solution, oxidation-reduction potential, and radionuclide concentration. Rocks and ground waters used in determining retardation factors should represent the expected equilibrium conditions in the geologic system under investigation. Static test methods can be used to rapidly screen the effects of the factors mentioned above. Dynamic (or column) testing, is needed to assess the effects of hydrodynamics and the interaction of hydrodynamics with the other important parameters. This paper proposes both a standard method for conducting batch Kd determinations, and a standard format for organizing and reporting data. Dynamic testing methods are not presently developed to the point that a standard methodology can be proposed. Normal procedures are outlined for column experimentation and the data that are needed to analyze a column experiment are identified.
Solutions to Radionuclide Migration with Nonlinear Retardation Mechanisms in Backfill Material
Author: Harold M. AndersonPublisher:
ISBN:
Category : Bentonite
Languages : en
Pages : 70
Book Description
Radionuclide Migration Experiment - Overview 1990-1996
Author: Simulation of Radionuclide Retardation at Yucca Mountain Using a Stochastic Mineralogical
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 19
Book Description
This paper presents preliminary transport calculations for radionuclide movement at Yucca Mountain. Several different realizations of spatially distributed sorption coefficients are used to study the sensitivity of radionuclide migration. These sorption coefficients are assumed to be functions of the mineralogic assemblages of the underlying rock. The simulations were run with TRACRN1, a finite-difference porous flow and radionuclide transport code developed for the Yucca Mountain Project. Approximately 30,000 nodes are used to represent the unsaturated and saturated zones underlying the repository in three dimensions. Transport calculations for a representative radionuclide cation, 135Cs, and anion, 99Tc, are presented. Calculations such as these will be used to study the effectiveness of the site's geochemical barriers at a mechanistic level and to help guide the geochemical site characterization program. The preliminary calculations should be viewed as a demonstration of the modeling methodology rather than as a study of the effectiveness of the geochemical barriers. The model provides a method for examining the integration of flow scenarios with transport and retardation processes as currently understood for the site. The effects on transport of many of the processes thought to be active at Yucca Mountain may be examined using this approach. 11 refs., 14 figs., 1 tab.
Author: P. A. Smith
Author: