German energy company RWE and industrial services provider Bilfinger have completed decomissioning work at Mülheim-Kärlich nuclear power plant in Germany.
In 2017, RWE commissioned Bilfinger to dismantle the two steam generators, each of which weighs 450 tonnes and the project was completed this month.
“The safe and successful completion of the project shows that our concept for nuclear decommissioning is effective,” said Tom Blades, CEO of Bilfinger.
“Together with RWE we have been able to overcome all the challenges of this complex task in a spirit of partnership”.
The tight space conditions within the plants create logistical challenges, especially when it comes to the dismantling of large components.
To deal with the difficult conditions in the confined spaces of the control area, Bilfinger Noell, a Bilfinger subsidiary in Würzburg, Germany, developed a dismantling concept that met both the stringent safety standards of a plant undergoing decommissioning and RWE’s overall schedule for the process.
Application of the innovative technical solution spared cost-intensive conversion measures, as well as costly special transports to an offsite location for dismantling.
The process did, however, require continuous close coordination with the customer for practically every work step in the plant. The activities were carried out ‘in-situ’ in the installed state, and at the same time as the customer’s own dismantling activities.
Previous decommissioning processes often required the establishment of suitable transport routes, for example, the enlargement of the equipment hatch – a cost-intensive procedure that has now been eliminated with Bilfinger’s dismantling concept.
The special saws from the manufacturer HILTI that were deployed in Mülheim-Kärlich were adapted and further developed for the special challenges of being used in a nuclear power plant.
Decisive factors for the precise application of the powerful saws were various technical adaptations of the wire storage, the expansion of the cooling system and modification of the decontamination properties. In this way, the two portal wire saws could be used as cold cutters in the control area of the plant.
The free release measurement of the dismantled shells of the two steam generators – which make up a large part of the total mass – was completed and the shells were fed into the conventional recycling system.
The inner workings of the steam generators – 16,000 finger-thick tubes each – were expertly packaged as radioactive waste in approved containers. These will be transported to an interim storage facility next year before they reach the final storage facility at Schacht Konrad.