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Transient Diffusion from the Near-Field, A 3-D Model

Published online by Cambridge University Press:  25 February 2011

A. Bengtsson ,
B. Grundfelt  and
H. Widén
A. Bengtsson
Affiliation:
Kemakta Konsult AB, Stockholm, Sweden
B. Grundfelt
Affiliation:
Kemakta Konsult AB, Stockholm, Sweden
H. Widén
Affiliation:
Kemakta Konsult AB, Stockholm, Sweden
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Abstract

A study of near-field radionuclide migration is presented. The study [1] has been performed in the context of the SKB91 study which is a comprehensive performance assessment of disposal of spent fuel. The objective of the present study has been to enable the assessment of which nuclides can be screened out because they decay to insignificant levels already in the near-field of the repository.

A numerical model has been used which describes the transient transport of radionuclides through a small hole in a spent fuel canister imbedded in bentonite clay into a fracture in the rock outside the bentonite. Calculations for more than twenty nuclides, nuclides with both high and low solubility, have been made. The effect of sorption in the bentonite backfill is included. Materials data for bentonite where taken from [2]. The size of the penetration hole was assumed to be constant up to the time when the calculations were terminated, 500 000 years after the deposition. The mass transport rate is controlled by diffusion. The model is three dimensional.

This paper describes the geometry of the modelled system, the assumptions concerning the transport resistances at the boundary conditions, the handling of the source term and obtained release curves.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 257: Symposium – Scientific Basis for Nuclear Waste Management XV , 1991 , 667
Copyright
Copyright © Materials Research Society 1992

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References

REFERENCES

1. Bengtsson, A. and Widén, H., Transient Nuclide Release Through the Bentonite Barrier, SKB91, SKB TR 91-33, May 1991.Google Scholar
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