The loading of fuel assemblies into the Olkiluoto 3 (OL3) EPR in Finland began on 27 March, utility Teollisuuden Voima Oyj (TVO) has announced. The move follows the receipt of a permit from the country's Radiation and Nuclear Safety Authority (STUK) the previous day. The process of loading the fuel assemblies into OL3 is expected to take about one week, TVO said.

Workers at OL3 have already practised loading fuel assemblies into the reactor's core (Image: TVO)

The fuel for OL3 arrived in Olkiluoto in 2018. A total of 241 fuel assemblies manufactured in Framatome's plants in Germany and France will be transferred from storage and loaded into the reactor vessel to constitute the first core.

To carry out the loading operations, an integrated team of about 40 employees from TVO, Areva and Framatome has been formed. It includes around 15 fuel handlers, personnel specialised in fuel handling operations, and four neutronics engineers in charge of monitoring the core during loading.

The loading of fuel will be followed by a commissioning phase lasting several months during which TVO will conduct a new series of hot functional tests to verify the plant's systems work correctly. The previous hot functional test - carried out without nuclear fuel in the reactor - was completed in 2018.

"The most important test is the hot functional test, in which the reactor and turbine island is tested for use," TVO said. "During testing, dozens of separate tests are performed with different pressure and temperature levels."

These tests must be completed before the unit achieves first criticality and commissioning for commercial operation. TVO requires authorisation from STUK before advancing from one commissioning phase to another. TVO was granted an operating licence by the Finnish government for OL3 in March 2019.

"Through the fuel loading, Olkiluoto 3 is now a nuclear power plant, and we are a significant step closer to the realisation of Finland's greatest single act for the climate," said Marjo Mustonen, senior vice president for electricity production at TVO.

OL3 is scheduled to be connected to the grid in October this year, with regular electricity production due to start in February 2022. According to the commissioning programme, the plant will produce 1-3 terawatt-hours (TWh) of electricity with varying power output during the period between grid connection and the start of regular electricity production. Once operating at full capacity, the OL3 plant will produce about 13 TWh of electricity annually and meet about 14% of Finland's electricity demand.

In December 2018, unit 1 of the Taishan plant in China's Guangdong province became the first EPR to enter commercial operation, and was followed by Taishan 2 in September 2019. The loading of fuel into the Flamanville EPR in France, construction of which began in December 2007, is now scheduled for the end of 2022. Two EPR units are also under construction at Hinkley Point C in Somerset, England.

Researched and written by World Nuclear News