Canada’s Ontario Power Generation (OPG) said on 2 September that it is "ready to execute" refurbishment of the Darlington NPP and remains within the CAD12.8bn ($9bn) estimate for the project, which is to start next month. All four of the plant's Candu units are refurbished over the next 10 years, and the 40-month project to refurbish unit 2, starting in October, will be the first. The refurbishment comprises over 500 projects which OPG has subdivided into five work bundles.
These include retube and feeder replacement, which involves removing and replacing the fuel channels, calandria tubes and feeders inside each reactor. The four turbine generator sets will be inspected and repaired and analogue control systems will be replaced with new digital control systems. Steam generators will be subjected to mechanical cleaning, water lancing, inspection and maintenance. Work on balance of plant will include smaller projects to replace or repair components on both the nuclear and non-nuclear side, such as heavy water and cooling systems, electrical systems, piping and valve work.
All the necessary materials have been delivered to the site, training of workers has begun and a detailed execution plan has been drawn up. Preparations have included using a mock-up reactor, first to test tools and procedures and then to train staff. The 3,512MWe Darlington NPP supplies about 20% of Ontario's electricity and, to ensure a reliable supply of low-carbon power during the refurbishment program, OPG will seek regulatory approval to continue operating its Pickering NPP until 2024.