PROJECT MODULES
- Module 1 -
Buffer Construction Technology for Horizontal Disposal Concepts
The challenge: design and construction of buffers for a horizontal disposal drift.
The buffer is the engineered barrier, usually made of material such as cement or bentonite (possibly mixed with sand), which is placed between the radioactive waste container and the geological formation surrounding the disposal drift.
Within ESDRED, 3 engineering options for waste emplacement are considered leading to 3 designs and therefore 3 prototypes:
- the buffer is prefabricated in a surface facility, then transported to the underground repository and positioned in the disposal cell ; then the waste canister can be emplaced
- the waste canister is emplaced in a large container, (so-called "super-container") which includes part of the buffer ; once the super-container is emplaced in the disposal drift, the annular space is then filled with a granular buffer
- the waste canister is placed on a prefabricated solid buffer cradle and then a granular buffer material is used to fill the disposal drift
The 2 last options look rather similar, but the volume of granular buffer material required and the emplacement technology used, (including the possible compaction), are different.
Case 1: This project will focus on the prefabrication and pre-assembly technology of bentonite buffer rings. Emplacement of the rings assembly will be studied in Module # 3.
Case 2: This project will focus on backfilling with granular buffer material the annular space between the super-container and the tunnel liner after the supercontainer has been placed in the disposal drift.
Case 3: This project will focus on the backfilling technology after waste canister emplacement.
1° The waste canister is emplaced on the cradle
2° Buffer material is backfilled in the disposal drift (possibly excavated slightly downwards)
Download: ESDRED-Module 1 pdf
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