When KKM closed for operations in December 2019, there were 418 fuel elements in the plant. They cooled down in the fuel element pool until they were ready for transportation. In April 2022 the first spent fuel elements were sent to the interim storage facility in Würenlingen, with multiple transport campaigns following. This required a total of 66 shipments with special transportation arrangements. With the removal of the last fuel elements, the level of radioactivity in KKM has been reduced by over 99 per cent.
For a number of reasons, the complete removal of nuclear fuels is the most important interim target in the decommissioning. This means KKM no longer represents a potential nuclear hazard. With the end of transportation, the volume of radioactivity at KKM has reduced significantly. There is no fissile nuclear material nor heat-producing waste left in the plant, which makes it much simpler to handle facilities and systems – for one thing, cooling is no longer required. In the coming years the aim will be to remove the residual levels of radioactivity from the plant.
“With prompt planning and the extensive consolidated experience of the employees involved, all transport runs went off without a hitch,” says Stefan Klute, Head of Nuclear at BKW. The transport runs have now concluded at the earliest possible opportunity. The early removal of nuclear fuels has a positive impact on the remaining processes in the decommissioning. Regulatory requirements for the cooling of fuel elements and monitoring of reactivity no longer apply. Other systems can be decommissioned, and some processes will be much simpler without nuclear fuels. However, Stefan Klute stresses that despite the early removal of nuclear fuels, safety remains the number one priority and that the disassembly work will continue with the same level of care as before.
The removal of nuclear fuels is the essential prerequisite for the transition to the second decommissioning phase. BKW lodged the corresponding application with the Swiss Federal Nuclear Safety Inspectorate (ENSI) back in late June 2022. Phase 2 of decommissioning will end with the radiation assessment of the entire site. This would confirm that all radioactivity had been removed from the plant and from the site.
You can find further information on the decommissioning website.