Olkiluoto EPR prepares for fuel loading

Hot functional tests have been completed at the Olkiluoto 3 EPR, Finnish utility Teollisuuden Voima Oyj (TVO) announced today. The company said preparations have already started for loading fuel into the core of the 1600 MWe pressurised water reactor ahead of its start-up later this year.

Workers in the control room of OL3 during hot tests (Image: TVO)

Cold functional tests - which are carried out to confirm whether components and systems important to safety are properly installed and ready to operate in a cold condition - began at the first-of-a-kind EPR last June and took about four weeks to complete. The main purpose of those tests was to verify the leak-tightness of the primary circuit.

Hot functional testing of the Olkiluoto 3 (OL3) EPR began in December. These key pre-operational tests ensure coolant circuits and nuclear safety systems are functioning properly before fuel is loaded. They are the first tests at plant-level where the reactor and turbine plant are operated as a whole, although still without fuel. During the tests, the water temperature and the pressure of the primary circuit were gradually increased to the level where they would be during actual operation. During the hot testing stage, more than 200 systematic tests were carried out at different pressure and temperature levels, TVO noted.

The final phase of the hot functional testing programme involved driving the turbine with steam for the first time. During the tests, the turbine - with a 68-meter-long shaft and a rotating weight of 1500 tonnes - was operated at 1500 rpm using steam produced by the thermal energy of the main circulation pumps.

"This was an extremely important phase of the commissioning process, with the nuclear island and the turbine island operating for the first time together as an entity," said TVO's OL3 Project Director Jouni Silvennoinen. "The hot functional tests proceeded well and provided us with valuable experience and capabilities for nuclear commissioning."

TVO added that the preparatory phase for the loading of the fuel had started immediately upon completion of the hot functional tests and would continue for several months. "Fuel loading will mark the start of the final stage of the project - nuclear commissioning," it said.

Fuel loading will begin once a safety assessment of Olkiluoto 3 is carried out by the Radiation and Nuclear Safety Authority and a decision by the Finnish government to issue an operating licence.

TVO said it anticipates loading the 241 fuel assemblies into the reactor in the autumn. A total of 128 tonnes of fuel for the EPR has already been delivered to the Olkiluoto site in southwest Finland.

Under the latest schedule for Olkiluoto 3, grid connection takes place in December, with the start of regular electricity production in May next year. The unit's ramp-up programme will see it produce 2-4 TWh of electricity, at varying power levels between those dates.

Fuel loading fuel at the Taishan 1 EPR in China's Guangdong province began last month following the issuance of a permit from the Chinese regulator. The unit is later this year scheduled to become the first EPR reactor to enter operation. Fuel loading at the Flamanville EPR in France is scheduled to begin in the fourth quarter of this year.

Researched and writtenby World Nuclear News