STUK grants Posiva permission for production of tunnel backfill material
Posiva has received permission from the regulatory authority to produce backfill material, which is bentonite clay of the right composition, for the final disposal tunnels for spent nuclear fuel. The material is the first actual engineering barrier whose production will now start.
In practice, the production plant for the tunnel backfill material has been ready for operation for some years already. In the start-up meeting of the production plant, which has now been held, the input data for the production phase of the backfill material for the final disposal facility were reviewed together with the producer (Lux Mineral Services, LMS), in order to establish the production capability of the plant.
The start-up meeting was followed by an inspection of start-up readiness by the Radiation and Nuclear Safety Authority of Finland (STUK). Based on the inspection, STUK concluded that Posiva can start the production of the tunnel backfill for the first disposal tunnel.
- This is a significant decision and an important milestone for Posiva, as this is the first of the several engineering barriers designed for the isolation of the final disposal facility that can now be moved to the production stage, says Posiva’s Mika Niskanen who is the system owner of the buffer, the backfill, and the tunnel sealing.
4,000 tons of raw material ready and waiting
Posiva’s "clay plant" is located in an industrial estate in western Finland, safely ensconced among other industries. At present, the clay factory, or the production plant of granular backfill, has a stock of some 4,000 tons of backfill raw material waiting to be processed. The production process will be started at the turn of May-June and the production of the tunnel backfill material is estimated to continue until the end of the year.
The next major points with the tunnel backfill material include the construction inspection of the finished material after production and, as the Trial Run of Final Disposal proceeds underground, the test installation of the bentonite batch that has already been produced and undergone the construction inspection.
The purpose of the Trial Run of Final Disposal to be carried out in the ONKALO® facility in Olkiluoto is to test the complete final disposal process starting with the encapsulation of the spent nuclear fuel through to the emplacing of the canister in the deposition hole and up to the backfilling and closing of the tunnel. However, the short trial tunnel only comprises four holes and instead of real spent nuclear fuel, dummy elements will be packed in the canisters.
Teksti: Pasi Tuohimaa, kuva Antti Mustonen