Refurbished OPG reactor cleared to begin fuel loading

02 December 2022

Canada's nuclear regulator has given Ontario Power Generation (OPG) the go-ahead to load fuel into Darlington unit 3 after removing the first regulatory hold-point for the refurbished reactor.

Darlington (Image: CNSC)

Canadian Nuclear Safety Commission (CNSC) Executive Vice-President and Chief Regulatory Operations Officer Ramzi Jammal notified OPG by letter that the OPG has met the conditions for the removal of the hold-point "and fuel may now be loaded into the Unit 3 core".

OPG is refurbishing all four Candu units at Darlington in a 10-year, CAD12.8 billion (currently about USD9.5 billion) project that will enable the reactors to operate for the next 30 years. Darlington 3 is the second unit at the site to undergo refurbishment: Darlington 2 has already been refurbished and returned to service in June 2020.

Refurbishment of a Candu reactor involves removing all the reactor's fuel and heavy water and isolating it from the rest of the power station before it is dismantled. Thousands of components, including those that are not accessible when the reactor is assembled, are inspected, and all 480 fuel channels and 960 feeder tubes are replaced during the high-precision rebuild. Reassembly of the Darlington 3's reactor core was completed in July.

Hold points are mandatory checkpoints where CNSC approval is required before the licensee - OPG - is allowed to move on to the next stage of the process to return the unit to operation. Each step ensures verification that all required testing had been properly done and that systems function as planned in safe condition. Three additional regulatory hold points must be removed before the unit can reach criticality and return to service.

The refurbishment of Darlington 3 began in September 2020, and is currently slated for completion in the first quarter of 2024. Refurbishment of unit 1 began in February this year, with completion expected in the second quarter of 2025. Preparations are under way for work on Darlington 4 to begin in the third quarter of 2023.

OPG has also applied to the CNSC for a licence to construct Canada's first grid-scale small modular reactor at Darlington, which is the only site in Canada currently licensed for new nuclear build. The company has selected GE Hitachi's BWRX-300 design and has previously said it expects to make a construction decision by the end of 2024 with a preliminary target of 2028 for plant operations.

Researched and written by World Nuclear News