Process-system tests have begun at the EPR reactor under construction at unit 3 of the Olkiluoto NPP in Finland, marking an "important milestone" for the project, according to plant operator Teollisuuden Voima Oyj (TVO). An Areva-Siemens consortium is building the 1,600MWe EPR but the project is more than nine years delayed according to the original schedule and significantly over budget. Regular electricity production from the new unit is now expected to start in late 2018, TVO said earlier. The seawater cooling system will be tested first, paving the way for further system testing during the first half of 2016, TVO said. The main electromechanical installations, including piping works, will be completed during the same period. Jouni Silvennoinen, TVO's senior vice-president responsible for the Olkiluoto-3, said the project has all "prerequisites necessary" to proceed according to schedule. Testing of the instrumentation and control (I&C) systems began in January.
TVO said earlier this year that the two operational boiling water reactor (BWR) units at Olkiluoto generated a combined total of 14.26TWh of electricity in 2015. However, the 880MWe Olkiluoto 1 was shut down on 8 April to replace defective fuel rods. TVO said preliminary inspections showed that three fuel assemblies need to be removed and replaced because of the defective rods. There are 500 fuel assemblies in the reactor core and each assembly has almost 100 fuel rods, TVO said. The company said the operation will begin on 11 April and will take about one week, during which the plant will be offline. According to TVO, the defective rods released radioactive substances into the reactor's water, but posed no danger to the environment.