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Workreport 2007-17

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Name:

Foreign Materials in the Repository - Update of Estimated Quantities

Writer:

Hagros, A.

Language:

English

Page count:

62

Summary:

In a repository for spent nuclear fuel, a variety of materials are used during the construction process and during the operation of the repository. In addition to materials necessary for the construction and operation, some materials may be transported into the repository through the ventilation air, as emissions from vehicles, as waste produced by the staff etc. Both of these two types of materials are considered here and their quantities - both the introduced quantities and the quantities that remain after closure - in the repository constructed at Olkiluoto in Eurajoki, Finland are estimated here based on new information. This work is intended to update the estimations that have been made previously, and it takes advantage of the experience collected during the construction of the underground rock characterisation facility ONKALO at Olkiluoto. During this construction process, the quantities of the different construction materials introduced into the underground openings have been monitored and they form a basis for estimating the quantities to be used in the future.

The estimations made in this report are specific to a KBS-3V type repository and to the Olkiluoto site, although in some cases more generic information has been used, particularly when the relevant quantities have not been monitored in the ONKALO. The estimations are based on the new repository layout produced in 2006 and consider the latest plans for grouting and rock support. As these plans are generally not final yet, several different alternative plans are assumed when necessary. Also two different strategies for the backfilling of the tunnels are considered.

The most significant differences with respect to the results of an earlier estimation are related to the materials used in grouting, shotcreting and in support bolts. In the cases where a mixture of bentonite and crushed rock is the used backfill alternative, gypsum and cement are the materials with the largest quantities remaining in the repository. The materials with the next largest quantities are carbonates and organic materials. If the chosen tunnel backfill alternative is Friedland clay, the material with the largest quantity is gypsum, followed by pyrite, organic materials and cement. The selection of the backfill alternative has a significant impact on the quantities of several important foreign materials and their relative abundance, whereas the differences between the grouting and shotcreting alternatives are minor in terms of total material quantities.

Keywords:

Foreign materials, construction materials, Olkiluoto, nuclear waste, disposal, repository, KBS-3V

File(s):

Foreign Materials in the Repository - Update of Estimated Quantities (pdf) (276.6 KB)


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