Originally Posted by wwillson
Thanks for posting - your updates are always interesting
Thanks Wayne!
I'm really hoping to see some above nameplate performance from DNGS 2 when it is run-in. It has a new generator, which means it should theoretically produce more power than the original one. If you look at Pickering, I'm not allowed to speak to specifics, but Unit 5 is an obvious stand-out, producing 20MW more than nameplate, so I expect a similar level of improvement at Darlington. Then there is Bruce 7.... Another obvious stand-out in the Bruce B units, all of which were rated originally for 817MW nominal. It is still using the original generator too... Plans are for Bruce to produce 7,000MWe post refurb, so we'll see how that ends up looking.
Speaking of thermal capacity, this is where things get a bit interesting and where the whole genesis of the CANDU 9 gets a bit funky. So Pickering is obviously not even CANDU 6, it's the first post-commercial construct and the result of Douglas Point, which was the first commercial unit, now shuttered, which sits decom'd at the Bruce site. It has fewer fuel channels and fewer bundles per channel than Darlington or Bruce, but of course Bruce is a fair bit older than Darlington. Bruce is basically the experimental site for what ended up being the CANDU 9/CANDU 900 (900MWe). And as such, there are some strange, STRANGE things at Bruce, particularly the A site, in which Unit 4 is/was markedly different from A units 1-3 and all units had massively higher thermal capacity than electrical because they were designed to run external steam services like the heavy water plant. All Bruce B units are rated, really, for 860MWe but nominal is 817MWe. I do not know why. B also has some funky thermal stuff going on, which I'll get into below.
The power output of a thermal plant is directly related to its thermal capacity. Thermal plants (steam) aren't overly efficient, as I'm sure Shannow could expound on far more than I, but generally, you are looking at around 30% efficiency from thermal to MWe output (NET). Nuclear plants run at lower thermal temperatures than other thermal plants, like say coal, which makes them a little less efficient still in this regard, but of course they are also non-consuming, so there isn't a fuel consumption penalty for that.
I drafted a spreadsheet a while back that contrasted the various thermal to electrical relationships of the plants in Ontario because I was curious as to how viable the idea of increasing the output of Bruce to 7,000MWe was. The plant, currently the highest output nuclear power plant in the world, produces 6,430MWe at present, so 7,000MWe is a rather massive uprate.
The thermal output of the units at Pickering is 1,744MWth
The electrical output of the units at Pickering is 515MWe (A)/516MWe (B)
The thermal output of the units at Darlington is 2,776MWth
The electrical output of the units at Darlington is 878MWe
The thermal output of the units at Bruce are:
A: Units 1&2: 2,620MWth
A: Units 3&4: 2,550MWth
B: Units 5&7: 2,832MWth
B: Units 6&8: 2,690MWth
The electrical output of the units at Bruce are:
A Units: 779MWe
B Units: 817MWe (obviously B7 is around 825MWe now)
We'll focus on B units 5 and 7 which immediately stand out as having higher thermal output than the units at Darlington. These units should, in theory, be able to push 900MWe unless there are other constraints in play.
Here's a shot of my spreadsheet, which determines the ratio from MWth to MWe and creates a potential scenario for Bruce:
this yields a NET output of 6,758MWe if Darlington efficiency level is reached at Bruce. you'll note that 5 and 7 are scratching 900MWe. I'm quite intrigued to see how this actually pans out in practice. They've made some significantly increases in output with all the original hardware on a few of the units, so the potential may actually be there.
As I touched-on earlier, Bruce was the "testing" site for what would eventually be the CANDU 9, which is what was built at Darlington. Originally slated to be 8 units, Chernobyl derailed the construction, produced massive cost overruns and resulted in the B site not breaking ground. It would have mirrored Bruce in having two separate CANDU 4-packs, different from Pickering where the 4-packs were connected in the middle. The CANDU 9/900 was supposed to be a larger for-export model (the 4-pack setup was exclusive to Ontario and never exported, nor attempted to be) but none were ever sold. The only successful for-export version of the CANDU has been the CANDU-6, which exists in many locations around the world and has an installed capacity of around 700-725MWe, depending on configuration.