Natural decay series radionuclide studies at the Needle's Eye natural analogue site
Characterisation of the mechanisms and rates of the transport and retardation processes which affect radionuclides in the geosphere is of fundamental importance in safety assessments for proposed radioactive waste repositories. Application of speciation and transport codes to well-defined natural geochemical processes is the only way of validating models used in such safety assessments, under the complex environmental conditions operating over timescales appropriate to the requirements of radioactive waste disposal. Natural decay series radionuclides are applied to the investigation of dissolution, transport and retardation processes affecting radionuclides in the environment around a uranium mineralisation site in south-west Scotland. A general geochemical description of the site is presented, in which the radionuclide source term is characterised and the release rate of uranium from the vein is estimated. Dispersion of uranium for distances of up to 50 m is observed in post-glacial silts, while the virtual insolubility and immobility of thorium under the same ambient conditions is confirmed. Three distinct retardation processes affecting uranium during groundwater transport are identified and characterised. Similarly, two retardation mechanisms are identified for radium.
Bibliographic Reference: EUR 13126 EN (1991) 61 pp., FS, ECU 6.25
ISBN: ISBN 92-826-2347-5
Record Number: 199110355 / Last updated on: 1994-12-02
Original language: en
Available languages: en