MIGRATION OF RADIONUCLIDES THROUGH THE GEOSPHERE - AN INTEGRAL MIGRATION EXPERIMENT
An integral migration experiment has been designed and is now under construction. It consists of a number of modules each containing several columns arranged in parallel. Its purpose is to reproduce in the laboratory the near field of a repository so that migration rates of nuclides of a special interest can be measured. Groundwater flows over the waste form and then through the columns which contain materials to represent the corroded canister, backfill, and geological medium. A method for on-line control of Eh has been developed. A single module pilot scale experiment based on 5 columns of Cornish granite has been operated to gain experience. A leachate arising from simulated HLW doped with radionuclides (equivalent age = 1000 years) was used. This leachate contained unusually high proportions of particulate activity, possibly due to the agitated conditions used during leaching. The retardation of activity by the columns was favoured by (a) a low flow rate (high residence time), and (b) a high surface area per unit void volume (low mean channel diameter). The retardation of different elements decreased in the order Np > Pu > Am > Tc > Cs. From these results it is estimated that a longer experiment (400 days duration) using columns of 1 mm granite particles would yield optimum information if designed with a residence time of about 32 days.
Bibliographic Reference: EUROPEAN APPLIED RESEARCH REPORTS - NUCLEAR SCIENCE AND TECHNOLOGY SECTION, VOL. 5 (1983), NO. 2, PP. 253-266 (EUR 8659 E).
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Record Number: 1989122010400 / Last updated on: 1987-01-01
Available languages: en