Objective
The main objective of this project is to address the question of whether colloids have critical impact upon the transport and retention of radionuclides in the geosphere and if they do, how the radionuclides associated with mobile colloids should be treated in safety assessment calculations. The aims are:
* to identify mobile phases which could be associated with radionuclides in the far field of a radioactive waste repository and to establish the conditions under which the colloidal transport is likely to be of importance. This is not limited to ambient colloidal distributions but also considers the near field as a potential source of colloids;
* to characterise colloid transport and radionuclide association with the mobil colloid phase using a number of established coupled processes models both on laboratory and field scales, and to assessi how robustly these models can represent the physico-chemical processes involved;
* to develop effective guidelines for recognizing and accounting for the signif cance of colloids in radionuclide transport;
* to assess the implications of colloid-borne transport of radionuclides upon performance assessment calculations.
In working towards these objectives, we propose a staged programme of concept development, experimental (laboratory and field-based) work and process model evaluation. In all natural and engineered media, the principal uncertainties lie in the spatial variability (that is, the geometric flow path structure and the distribution of physical and chemicali properties), and the extent to which this is incorporated into various types of model. In the proposed work, we shall work through various spatial scales, and at each stage ask whether the concepts and descriptions at the smaller scales are relevant, can be upscaled, or else should be represented by macroscopic, averaged, terms. Our emphasis will be on discussing those impacts of colloids which can provide critical perturbations to assessment calculations. The proposed modelling work supported by closely coordinated laboratory and field programmes will lead, to a consistent theoretical framework for colloidal systems involving radionuclides in the far field, covering simultaneously aqueous speciation, hydrodynamic phenomena and colloid stability. Such an integrated programme will thus address definitely the question of how colloid-assisted transport of radionuclides in the geosphere could affect the performance assessment calculations.
Project deliverables are:
* Development of effective guidelines for recognition of significance of colloi in radionuclide transport through the geosphere
* Characterization of colloid transport based on a self-consistent theoretical basis at both laboratory and field scales
* Assessment of implications of colloid-borne transport of radionuclides upon performance assessment calculations.
Duration of the proposed project is 4 years (in 2 two-year long phases).
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
CSC - Cost-sharing contractsCoordinator
OX11 0RA Didcot
United Kingdom