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Radionuclide Release from the Kbs-3 Repository-Sensitivity to the Variability of Materials and Other Properties

Published online by Cambridge University Press:  15 February 2011

L. Romero ,
Å. Andersson ,
L. Moreno  and
I. Neretnieks
L. Romero
Affiliation:
Department of Chemical Engineering and TechnologyRoyal Institute of TechnologyS-100 44 Stockholm, Sweden
Å. Andersson
Affiliation:
Department of Chemical Engineering and TechnologyRoyal Institute of TechnologyS-100 44 Stockholm, Sweden
L. Moreno
Affiliation:
Department of Chemical Engineering and TechnologyRoyal Institute of TechnologyS-100 44 Stockholm, Sweden
I. Neretnieks
Affiliation:
Department of Chemical Engineering and TechnologyRoyal Institute of TechnologyS-100 44 Stockholm, Sweden
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Abstract

Radionuclides leaking from a canister spread into the backfill material surrounding the canister and then migrate through different pathways into the mobile water in the rock fractures. In order to quantify uncertainties regarding the release to the far field, a sensitive analysis is performed for the uncertainties in the parameters governing the release.

For nuclides escaping through a damaged canister in a repository of the type KBS-3 [1], most nuclides migrate through the pathways appointing to the fracture intersecting the deposition hole and the disturbed zone below the tunnel.

The sensitivity analysis showed that the grade of impact on the release of uncertainties in the parameters cannot be generalized for all nuclides, however, some patterns of the influence can be given. Uncertainties in the hole size and uranium solubility for nuclides embedded in the matrix have a strong influence on the release. The adsorption capacity of the bentonite surrounding the canister and the hydraulic properties of the fractured rock in the short pathways to the mobile water have to be accurately known to reduce uncertainties in the release to the far field. For nuclides with a high diffusion coefficient in the bentonite, e.g. cesium and strontium, the hydraulic properties of the fractured rock nearest to the canister have to be well known. For the iodide, on the other hand, with a very low diffusion coefficient, uncertainties in the hydraulic properties have a very small effect on the release. The uranium release with a very high inventory is not affected by uncertainties in the hydraulic properties of the rock.

The released nuclide fraction through each pathway is not largely influenced by uncertainties in the transport properties of the backfill materials whereas uncertainties in the water flow rates in the zones in the rock where the water flows, have a strong influence on the nuclide release distribution.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 353: Symposium – Scientific Basis for Nuclear Waste Management XVIII , 1994 , 511
Copyright
Copyright © Materials Research Society 1995

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References

REFERENCES

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