​First, Darlington Nuclear’s Unit 2 reactor was taken apart. Now, it’s time to put it back together.

Refurbishment of the first of Darlington Nuclear’s four reactors began in October 2016. Since then, Unit 2 has been safely shut down and isolated from the operating station, defuelled and, in a most recent series of work, completely disassembled.

Now begins the work to rebuild the reactor to allow for 30 additional years of clean, reliable power production.

The Unit 2 reactor face at Darlington Nuclear Generating Station.
The Unit 2 reactor face at Darlington Nuclear Generating Station.

​The reassembly phase started with four days of calandria vessel inspection. During this time, a camera was insertedand remotely controlled to allow viewing of key areas, such as high-stress welds, reactivity mechanisms and moderator nozzles.

“The only time we can look at these key features of the calandria vessel is after the fuel channels and other components have been removed, so this can only happen now,” said Mike Allen, Senior Vice President, Nuclear Refurbishment.

This work is followed by tube sheet bore cleaning and inspection, and inspection of the bellows.

Then, reactor rebuilding begins with installation of calandria tubes, fuel channel assemblies, and lower feeders.

Putting the reactor back together necessitates quality workmanship at every single turn, said Allen.

“This requires precise control with every task, every torque and every weld,” he said. “Doing this with quality calls for following procedures and committing to build clean with each and every task.”

Unit 2 reassembly will take approximately one year to complete.

“There are 58 connected systems we need to rebuild in sequence to put this nuclear engine back together,” said Allen. “We know this won’t be easy, but we also know we have the right team to do it, and to do it safely and with quality.”


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