Posiva receives a unique welding certificate as the second company in the world
Posiva is launching final disposal for spent nuclear fuel, and it has been granted a unique welding certificate for friction stir welding (FSW) as the second company in the world. Posiva’s ISO 3834-2:2021 certificate authorises the company to seal the copper final disposal canister containing spent nuclear fuel by means of friction stir welding.
The Swedish final disposal company SKB holds a similar certificate. At this time, SKB’s certificate only covers friction stir welding for the bottom of the canister, not the sealing of the canister lid.
The certificate was granted by DNV in the Netherlands, which performs assessments for Posiva.
Unlike traditional welding processes, friction stir welding does not introduce heat into the canister; instead, a rotating tool uses friction to generate heat that will fuse the copper lid and canister together.
Requirement based on YVL Guide
The requirement for an ISO 3834-2 certificate originates from a Regulatory Guide on nuclear safety (YVL) issued by the Radiation and Nuclear Safety Authority (STUK). A certificate for a special process for a nuclear pressure equipment manufacturer is one of the prerequisites for Posiva to apply for STUK’s approval for the operating licence of the disposal facility.
- Our preparatory work deserves some praise, since even the auditor was surprised by how Posiva was able to land the certification at one go, says Senior Expert Tapio Nieminen from Posiva.
Posiva’s welding coordinator Oskari Piepponen is also happy with the granting of the certificate.
- I am glad that we were able to squeeze in the ISO 3834-2 certification in the midst of all our commissioning and test operation activities, Piepponen says.
The certificate is in force for three years. The application process is repeated every three years with updated welding documents. Periodic assessments are conducted annually. They verify that the activities and the in-field documentation are up to date.
Posiva Oy is the world’s leading provider of final disposal services that will start the final disposal of spent nuclear fuel in ONKALO®, excavated deep in bedrock, in the mid-2020s.
Text: Pasi Tuohimaa
Photos: Tapani Karjanlahti
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