Factors to Consider When Choosing Accounts Payable Services Providers.pptx
19 herold shaft seals for hlw repositories
1. Shaft seals for HLW repositories
Philipp Herold1, Michael Jobmann1, Wolfram Kudla2, Matthias Gruner2
1DBE TECHNOLOGY GmbH, 2TU Bergakademie Freiberg
7th US/German Workshop on
Salt Repository Research, Design and Operation
Washington, DC
September 7-9, 2016
ABSTRACT
The R&D project "Shaft sealing systems for final repositories for high-level waste (ELSA) –
Phase 2: Concept design for shaft seals and testing of functional elements of shaft seals", which
is funded by the Federal Ministry for Economic Affairs and Energy (BMWi), was initiated to
develop shaft sealing concepts for the two host rock options rock salt and claystone. These
concepts are to be modular in design so that they can be adapted to suit the eventual site
conditions. As no decision has yet been made on the choice of site for the final disposal of high-
level waste and spent fuel, generic shaft sealing concepts have been developed based on
currently existing host-rock data. Diversity and redundancy are basic design requirements for
shaft sealing of repositories for high-level waste and spent fuel. Bitumen/asphalt will fulfill these
basical requirements, in addition to clay-based sealing elements, such as binare mixtures of
bentonite. Within the ELSA projcet, two already existing conceptual designs of bitumen/asphalt
seals were tested in-situ and one new asphalt sealing system was developed and tested. All tests
showed that sealing systems made of bitumen/asphalt lead to a permeability close to initial host
rock permeability. Especially soft bitumen penetrates the EDZ and fills cracks, which was shown
by a microstructure analysis of the removed bitumen seals. Additional, in-situ tests were realized
for MgO-concrete and mixtures of crushed salt and clay. The in-situ tests of dynamic compaction
of mixtures made of crushed salt and clay demonstrate the suitability of this technology for
sealing construction. In a next step, the conventional equipment has to be modified for conditions
inside a shaft. The use of MgO-concrete and mixtures of crushed salt and clay is limited to rock
salt. Bimodal bentonite seals promissie functionally independent of the type of host rock.
Sealing elements made of conventional binare bentonite mixtures and equipotential layers were
tested in semi-scale tests, too.
