15 Jun (NucNet): Canada’s Ontario Power Generation (OPG) has begun reassembling the 878-MW Darlington-2 nuclear power unit as part of refurbishment works which started in 2016.

OPG said the unit has been safely shut down and isolated from the rest of the nuclear station, defueled and completely disassembled.

The reassembly phase started with four days of calandria vessel inspection and will be followed by tube sheet bore cleaning and inspection, OPG said.

Rebuilding of the reactor will begin with the installation of the calandria tubes, fuel channel assemblies, and lower feeders, the company said.

OPG said reassembly work will take about one year to complete.

Darlington-2 is the first of the station’s four Candu units to undergo refurbishment in a project that will enable the station to continue operations until 2055. All four units are to be refurbished in a phased CAD 12.8bn ($9.7bn, €8.4bn) project which is scheduled for completion by 2026.

Each of the four units will be taken out of service for three years for work to be carried out.

OPG’s plans call for refurbishment of Unit 2 to be completed before the start of work on Unit 3 to allow for the implementation of “lessons learned”. Work on Unit 3 is scheduled to begin in February 2020, on Unit 1 in July 2021 and on Unit 4 in January 2023.

Ten Candu units in Canada are to be refurbished between 2016 and 2033 – four at Darlington and six at Bruce. The Pickering nuclear station will continue to operate until 2024 to provide baseload electricity during the Darlington and Bruce refurbishments.