MCR vs Refurbishment, what gives?

OVERKILL

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As I've noted in a few previous threads, Ontario is in the process of refurbishing its nuclear fleet (except for Pickering, but we hope to change that) which is something that needs to be done about halfway through the expected life of a CANDU unit.

A refurbishment can be very broad or very narrow in scope, there's no single definition and it has been performed differently depending on the operator, which is what we are going to get into here.

The first refurbishment undertaken by OPG on a CANDU was actually started under the former Ontario Hydro and was at Pickering. This was a "narrow" scope refurbishment as it was primarily dealing with fuel channels and pressure tubes coming up on their hour limits. While there were other items replaced, it was not extensive and didn't get into replacing the generators or steam generators.

Presently, Ontario has two major refurbishment projects ongoing:

1. The Darlington refurbishment
2. The Bruce MCR and Life Extension program

You'll notice Bruce doesn't just call theirs a refurbishment, even though that's what it technically is. The reason for this is that there is more to what Bruce is doing than just dealing with the mid-life CANDU service, but then the same can be said for some of what is being done at Darlington, so, it's complicated, but OPG has still decided to use the term "Refurbishment" rather than giving it a different name that perhaps would better describe the activity.

Let's start with what is being done at Darlington:
1. Full feeder-tube replacement
2. Full fuel-channel replacement
3. Full calandria tube replacement
4. Generator replacement
5. Control system upgrades
6. Inspection and maintenance system upgrades

Note that the pressure tubes have been "updated" and are expected to provide a longer operating life than the original units so current EOL is not a firm figure, just an estimate.

The current projected operating end of life for Darlington, whose first unit was declared in service in 1990, is 2055.

Now, let's turn our attention to Bruce Power and their MCR and Life Extension project:
Activities at Bruce are focused around the same things being done at Darlington but include work to further extend the operating lives of the units themselves. While Darlington 2, which came back from refurb earlier this year was declared in service in 1990, Bruce 6, which is currently down for its MCR was declared in service 6 years prior, 1984. So already, there's a significant age difference there.

In addition to most of the tasks being done at Darlington Bruce is performing:
1. Complete Steam Generator replacement
2. Steam system upgrades to improve generator performance
3. Uprates with a goal to increase total site output to 7,000MWe

Life Extension activities are underway at the site presently and don't apply to any one unit. The oldest Bruce units will be approaching their mid 40's by the time they go down for refurbishment, so there is work being done outside of the actual core refurbishment that will allow the units to make their milestones despite going a decade+ longer than the units at Darlington before going down. Bruce Life Extension work plans to extend unit operating life to 2064 and beyond, per their most recent press release.

The Steam Generator replacement is a major component here I suspect in ensuring that the units are able to get to close to a century of operation. The Bruce units, being older, have more, and smaller, steam generators; 8 per unit vs 4 for Darlington. Pickering has 12 and significantly more in the way of heat transport equipment (pumps and the like) which would need to be replaced if the B units are refurbished. The SG's are manufactured by BWXT Cambridge.

More info from Bruce Power here:

Here is a Bruce SG:
1611689257667.png


The Bruce units have the highest thermal capacity of any in the fleet, but the Darlington units are of a more modern design. Current Bruce B units are producing ~825MWe on a 5% derate while the Darlington units, operating at 100%FP produce ~880MWe.

A telling photo from Unit 6 at Bruce when it went down for refurbishment:
AB7E5F36-C925-44A9-8291-98557E24360D_1_105_c.jpeg


Bruce is working with their fuel bundle supplier, Cameco, on an updated design that may allow the units to operate at 100% FP. If successful, it is quite possible for 880MWe to be achieved. The obstacle will be the A plant, as, despite having the same thermal capacity as the B units, the systems there were originally designed to produce 750MWe (currently producing >800MWe for 3 and 4) as the steam side was oversized to run a ton of systems onsite as well as the heavy water plant originally located behind it:
1611689967400.png


That's the first commercial CANDU, the single 220MWe Douglas Point, in the fore with the 4x Bruce A units in the background.

There had been hope that OPG would be adding uprates to the work done at Darlington, but being a publicly owned company, there is likely very little interest in improving output, as it doesn't exist to turn a profit, quite unlike Bruce, who is a private operator and paid a fixed rate of $0.077/kWh, so the more kWh they can produce, the more money they are going to make.

This ties into the fancy acronyms and broader scope being applied at Bruce. A longer plant life and higher output looks better for their bottom line, so it truly is more than just a refurbishment, it's an investment in greatly extending the operating lives of the units beyond what would typically result from a basic refurb.
 
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Slightly OT, but the generator floor pic reminded me of a tour I got of a now closed major coal fired power plant. It was awesome. The boiler side was hellish, hot, loud, but the generator side was as pictured here; spotless, quieter with a rumbling from the machinery.

There was a small inspection window for the commutators. Above it was a small official placard that said "Please do not knock, it drives the hamsters crazy"
 

OVERKILL

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Slightly OT, but the generator floor pic reminded me of a tour I got of a now closed major coal fired power plant. It was awesome. The boiler side was hellish, hot, loud, but the generator side was as pictured here; spotless, quieter with a rumbling from the machinery.

There was a small inspection window for the commutators. Above it was a small official placard that said "Please do not knock, it drives the hamsters crazy"

You ever see the hall floor pics I posted from Darlington? Its hall is stunning, each unit is a different colour. It's probably the most beautiful turbine hall in any plant IMHO.
 
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