Fuel loading begins at Canada's Darlington unit 2

13 November 2019

Fuel loading has begun at Darlington 2, Ontario Power Generation (OPG) has announced. The refurbishment of Darlington 3 is now expected to start in the second quarter of 2020 as the company applies lessons learned during the refurbishment of unit 2.

Fuel loading is now under way at Darlington 2 (Image: OPG)

The refurbishment of Darlington 2, which began in October 2016, is now 90% complete, OPG President and CEO Ken Hartwick said. "As we mark this important milestone on the 10-year Darlington Refurbishment project, we remain focused on delivering Canada’s largest clean energy project on time, and on budget," he added.

The 878 MWe (net) Candu unit is the first of Darlington's four reactors to undergo refurbishment in a CAD12.8 billion (USD9 billion) project scheduled for completion in 2026. This involves disassembling the defuelled and isolated reactor, using specialised and mostly remote-controlled tooling to remove the components of the 480 fuel channels including feeder tubes, end fittings, pressure tubes and calandria tubes. Detailed inspections of the inside of the calandria and the holes through which fuel channels are fed and secured are carried out before work begins to reassemble the reactor.

The reassembly of Darlington 2 began in June 2018. By late October, all 960 feeder tubes had been installed and a total of 40 out of 58 major plant systems declared available for service.

OPG worked with BWXT Nuclear Energy Canada over five years to develop a detailed plan for loading each of the 6240 new fuel bundles into the core in the correct location and sequence. This work series involves the insertion of shield plugs, closure plugs and fuelling the core with fuel bundles.

Delayed start for unit 3 refurbishment

The next unit to undergo refurbishment will be Darlington 3. By the end of the third quarter this year, 94% of the engineering design for its refurbishment had been completed, and planning and readiness activities remain on track, the company said.

"OPG continues to refine our four-unit refurbishment schedule based on operating experience and our detailed review of more than 3000 lessons learned from Unit 2 refurbishment. In response to the recently revised schedule for Unit 2 refurbishment, we will now commence Unit 3 refurbishment in the second quarter of 2020, instead of the first quarter of 2020," OPG said yesterday.

"This decision was made to enable the project team to dedicate their focus to successfully returning Unit 2 to service ahead of the start of work on Unit 3, as initially planned. It also allows the team to bring preparatory work forward, ahead of Unit 3 breaker open, when the reactor will be taken offline."

The project team continues to work on plans and preparations for the refurbishment of units 1 and 4, based on operating experience and lessons learned from unit 2's refurbishment, OPG said. As of 30 September, CAD437 million had been invested in planning and prerequisite activities related to the refurbishment of unit 3, and total life-to-date expenditure on the project is about CAD6.4 billion. The project remains overall on budget and on schedule for completion in 2026 and will enable the units to operate for another 30 years, OPG said.

Researched and written by World Nuclear News