Karlsruhe. During last night, Unit I of the Neckarwestheim nuclear power station (GKN II) came back on line after its annual inspection. During the preceding weeks, the largest individual project involved comprehensive maintenance work on the three-phase generator in the non-nuclear section of the plant. In addition, a range of general checks and maintenance tasks have been carried out, and fuel elements have been replaced by new ones.
Investments in the future of the plant
"In this inspection we have once again invested in Unit I, and will also do so in future. This enables us to ensure that we can make even more improvements to the plant future, in line with the latest technical developments. Our investments in on-going improvement to Unit I since it was first commissioned are now almost worth twice as much as the original costs for the erection of the plant", explained Jörg Michels, technical managing director of the Neckarwestheim Nuclear Power Station.
IAEA: Neckarwestheim I can still be operated for another 30 years
The company’s ongoing investments and efforts have resulted in safety levels that comply with the highest international standards, as confirmed to EnBW by the International Atomic Energy Agency (IAEA), after the OSART (Operational Safety Review Team) mission in 2007. According to the IAEA, Unit I can still be operated for another 30 years. Excellent results were also achieved during the security inspection performed in accordance with the German Nuclear Power Act. Just like all other nuclear power stations operated by EnBW, Neckarwestheim I's security level is clearly higher than the standard specified for new plants by the IAEA. In addition, EnBW has a pioneering, safety management system, which operates across all sites, and provides continual improvement and quality assurance for operational processes.
Application for the transfer of residual power capacity to be asserted strongly
"Our plant technology, operational organisation, and the levels of training of our staff, meet the highest international standards, even exceed them", concluded Jörg Michels. "For this reason we continue to believe that our application to divert residual power capacity from Unit II to Unit I is legally acceptable, well founded and correct. We have taken legal action against the rejection of our application to transfer residual power capacity by the BMU (German Ministry for the Environment) in the summer, this year, and will intensify our legal efforts in the future. If politicians and the general public should also decide in favour of cancelling the limitation on operating life, then our plants are prepared for continuing operation in every way."
Successful completion of two-phase annual maintenance
The annual maintenance of Unit I was split into two phases this year. The first phase took place in spring this year. At that time, the necessary routine maintenance tasks were performed in the plant, as well as a preliminary inspection of the three-phase generator. In spring this year, the maintenance work on the generator would have lasted too long to fit into the maintenance timetable for EnBW power stations, so, in consultation with regulatory authorities, this task was delayed until the autumn. "The maintenance works have been performed successfully," reported Helmut Scherla, Unit I director. "Among other things, they included dismounting the so-called "generator armature" – a shaft-like piece of equipment that rotates in the generator stator, sending it away to the manufacturer for reconditioning, and then reinstalling it." The remaining tasks that needed to be carried out in the plant were also completed according to plan. "We performed a pressure test on the primary circuit and an ultrasound test on the reactor pressure container. In the inflow construction, a new substation was installed. We reconditioned several components from the ground up: one of the three main feed pumps, and one of the three main condensed-steam pumps, two of the four cooling water pumps, one of the four cooling tower pumps, and also a wide range of different electrical substations and transformers", reported Helmut Scherla. During the annual maintenance, some 1,500 employees from manufacturing and special firms provided assistance to the GKN team. Together, the operatives involved in the inspection performed around 5,000 separate tasks.
These maintenance tasks were carried out under the supervision of the Baden-Württemberg Department of the Environment, and were monitored by inspectors from the Technical Inspection Authority (TÜV), KeTAG (the Baden-Württemberg Nuclear Power Consultant Consortium) and the MPA (state material research laboratory, Stuttgart). After approving the works, the Department of the Environment agreed to the plant being restarted.
Unit I of the Neckarwestheim nuclear power station is a pressurised water reactor that produces 840 megawatts of electricity. The plant has been in operation since 1976 and produced over five billion kilowatt hours of power in 2007.