trouble with reactor

[foamy]

I'd much rather a system that can extract all the heat from a reactor albiet with minor non-utilization in the exchangers/turbines than one balanced the other way around.

In principle I agree. The reactors set the maximum sustained average power production, while the turbines set the maximum instantaneous peak power production, and it is clearly sensible to have the latter a little higher than the former. In practice I confess that my standard small and medium nuclear power plant designs have 3% lower turbine capacity than reactor capacity, for reasons of simplicity and symmetry of design. (And if that 3% really matters, then it's well past time to build another power plant anyway!)

Heh, that's very true. But sometimes it'll sneak up on you. I'm in a fairly long-running MP game where a nuke plant was plopped down months ago by someone else and I hadn't checked on it in ages because the factory was still working fine full bore -- until I happened to check on the actual power stats for another reason entirely, only to discover that the accumulator backups that were installed, oh, about two hundred hours ago now, were regularly having to contribute power.

Only the supplemental solar array was allowing the power to actually average out over a day. I was within a few hundred megawatts of brownout without realizing it :v

[Yoyobuae]

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[foamy]

If you run the steam turbines at 100% rather than 85% then you have an extra 15% safety margin before having to expand power plant. If you want to have a 30% safety margin then you would expand when reaching 70% rather than 55% of max steam turbine output.

What? That's not how safety margins work. If you're running turbines at 100% you have exceeded all your safety margins; your nuclear plant is running flat out, and you either need to redesign or expand it. If you're under that, then the fact that your heat exchangers cap out at 97% v. 100% is not a significant UPS factor because they're all under-utilized anyway.

My preferred ratio is 1:12:20, offshore: heat exchangers: turbines. The limiting factor in that ratio, aside from the reactor heat, is the water supply. Those 1,200 units of water a second directly translate into exactly 116.4 MW of power. 20 turbines going flat out happens to consume exactly 1,200 units of steam, so, again, precisely 116.4 MW of power is produced. Those two are in exact balance.

Twelve heat exchangers can process 1248 units of water, for 120MW. So, running the turbines and offshore pump at maximum capacity, the heat exchangers hit a utilitzation rate of exactly 97%. This is not really a major issue, y'know? I'd rather have a single exchanger running at 1/2 nominal capacity than a reactor and a turbine bank and an offshore pump not working to their full specs.

EDIT:

Also if you're landfilling in a lake anyway, I think you'd be better served putting the offshore pumps between the reactor and the heat exchangers, instead of at the end of the heat exchanger row. Means you can use a much narrower body of water.

[Yoyobuae]

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[foamy]

What? That's not how safety margins work. If you're running turbines at 100% you have exceeded all your safety margins; your nuclear plant is running flat out, and you either need to redesign or expand it. If you're under that, then the fact that your heat exchangers cap out at 97% v. 100% is not a significant UPS factor because they're all under-utilized anyway.

You are splitting hairs here.

My comment was in reference to the more common setup of 1x heat exchanger -> 2x steam turbines. That setup can only supply 85% of the steam the turbines need. By supplying less steam than the turbines need then the power output would be 15% less than fully supplying the steam turbines which means you'd need to expand nuclear power sooner.

What? No, you wouldn't need to expand any sooner -- as long as you've got the exchangers to process the heat and the turbines to eat the steam you'd need to expand at exactly the same time: When your power draw exceeds the output of the reactors. People overbuilding the turbines doesn't impact that at all, you could put ten thousand turbines behind a single heat exchanger and it'd still hold true.

That extra capacity of the turbines in a 1:2 layout isn't used but I guarantee you that the exchangers will be built to consume more heat than the reactors generate, so there's no actual loss of generating capacity from the overall installation -- just some turbines that can't hit 100% sustained utilization. And while carrying an extra 25% in turbines in that sense is bad from a UPS standpoint, 1, optimizing everything for UPS is a cancerous viewpoint anyway; and 2, it does allow for some slack if you peak load for whatever reason. A lot of the 1:2 style designs even carry battery tanks for that purpose.