Forsmark NPP, owned by Forsmarks Kraftgrupp AB and where the energy company Vattenfall is the majority owner, is the most recently built nuclear power plant in Sweden; the plant was commissioned in the 1980s. The total power output is 3,280 MW with an annual production of 25 TWh, which is approximately one sixth of Sweden's total electrical energy consumption.
Over a period of ten years, the owners have invested in an extensive investment programme at Forsmark to prolong the service life of the reactor and to increase the output. The plan is to operate the units for many years to come. In order to maintain high availability of the NPP, it is necessary to be able to perform refurbishments and repairs of the rotors.
The company investigated alternatives for qualified suppliers to secure long-term access to external support and turned to Fortum eNext for the refurbishment of the spare rotor for Forsmark units 1 and 2.
“We have vast experience working with large generators, including the water-cooled type for nuclear applications. Fortum also owns a workshop where newly built ASEA turbo-generator rotors were balanced in the past. This type of balancing facility with water is quite unique,” says Jonas Holmgren, Key Account Manager at Fortum eNext.
All three Forsmark reactors are boiling water reactors designed by Asea-Atom, and the generator is based on the original ASEA design with water-cooled rotors. It is among the very few 2-pole rotors for NPP’s in the world. This generator has a rating of 680 MVA , and the rotor weight is 57.7 tonnes, length approx. 11 meters, diameter 1.15 meters and operating speed 3000 rpm.
For this order, the FRR2 rotor, Fortum eNext will manufacture and replace a cracked rotor slot wedge. Inspections and replacement of insulated bushings will be performed at the same time. Finally, the rotor will be tested and balanced with water in the balancing facility.
A steady source of CO2-free electricity
Climate change and the transition to a low-carbon energy system means that reliable, emission-free power generation is more important than ever. Both companies share the same vision of a clean-energy future and, as a CO2-free energy production method, nuclear power plays a key role in their strategies.
“We are very proud that Forsmarks Kraftgrupp trusted our competence and capabilities in the delivery of this kind of service. The availability of the existing NPPs in Sweden is crucial and having a supplier nearby is worthwhile to minimise downtime,” Jonas Holmgren says.