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> Why do you think nuclear plants run at 100% capacity 24/7? The primary reason would be economic. Fuel costs IIRC are really low but capital-expenses (especia

> Why do you think nuclear plants run at 100% capacity 24/7? The primary reason would be economic. Fuel costs IIRC are really low but capital-expenses (especially safety engineering / politics / convincing the people nearby that the plant is safe) is so costly. When you have cheap-fuel but expensive machines, it makes sense to run closer to 100%. If you have expensive fuel but cheap machines (ex: Gas turbines), it makes sense to run in a "peaker" fashion. ----- That being said: I've heard that older nuclear plants are "baseload" designs, in that they _CANNOT_ turn off or feasibly regulate their power output. I mean, they obviously "can" turn off, they all have control rods for safety. But they're clearly not using them to regulate the power output.

Lascaille 5y ago
>But they're clearly not using them to regulate the power output. No, you heard wrong. They're often the last or second to last type of plant that's called upon to alter supply to match demand, but they don't run 100% 24/7.
- cinntaile 5y ago
  They want to run them nearly 100% 24/7 for economic reasons though. Also what is the effect of regulating with control rods on the fuel, does it have an impact on how often the fuel needs to be changed?
  - Lascaille 5y ago
    >does it have an impact on how often the fuel needs to be changed Yes, fissonable elements in the fuel are consumed in a manner that's proportional to output. So if you run at 25% output your fuel needs to be changed (example) every 4 years, if you run at 100% output your fuel needs to be changed every year. But it is not 100% proportional, for example, 15% of the plant's output is required simply to run the plant's accessories. So it is advantageous to run at 100% output if you can.
    - cinntaile 5y ago
      Another comment in this thread, I can't find it now, said that lower output past a certain level did lead to having to change the fuel faster. I don't know who's correct but it feels strange that this would be a linear relationship, these kinds of things don't tend to work like that.
cinntaile 5y ago
I recall reading that the fuel is 1/3 of the operating expenses, but I could be misremembering.
- ch4s3 5y ago
  About 28% as of 2018[1], but there have been some advancements since then. Half of that cost is enrichment and fabrication, and disposal is a factor too. It costs a lot less to fuel nuclear plants than coal plants, but maintenance is more costly for nuclear. Pricing in externalities or requiring scrubbers makes coal FAR more expensive. Natural gas is really cheap right now so that is largely what is undercutting Nuclear for base load power. It's worth noting that historically natural gas production/use has been far more dangerous than nuclear and far less scrutinized by regulators. [1]http://large.stanford.edu/courses/2018/ph241/wang-k2/ http://large.stanford.edu/courses/2018/ph241/wang-k2/

Lascaille 5y ago

>But they're clearly not using them to regulate the power output. No, you heard wrong. They're often the last or second to last type of plant that's called upon to alter supply to match demand, but they don't run 100% 24/7.

cinntaile 5y ago
They want to run them nearly 100% 24/7 for economic reasons though. Also what is the effect of regulating with control rods on the fuel, does it have an impact on how often the fuel needs to be changed?
- Lascaille 5y ago
  >does it have an impact on how often the fuel needs to be changed Yes, fissonable elements in the fuel are consumed in a manner that's proportional to output. So if you run at 25% output your fuel needs to be changed (example) every 4 years, if you run at 100% output your fuel needs to be changed every year. But it is not 100% proportional, for example, 15% of the plant's output is required simply to run the plant's accessories. So it is advantageous to run at 100% output if you can.
  - cinntaile 5y ago
    Another comment in this thread, I can't find it now, said that lower output past a certain level did lead to having to change the fuel faster. I don't know who's correct but it feels strange that this would be a linear relationship, these kinds of things don't tend to work like that.

cinntaile 5y ago

I recall reading that the fuel is 1/3 of the operating expenses, but I could be misremembering.

ch4s3 5y ago
About 28% as of 2018[1], but there have been some advancements since then. Half of that cost is enrichment and fabrication, and disposal is a factor too. It costs a lot less to fuel nuclear plants than coal plants, but maintenance is more costly for nuclear. Pricing in externalities or requiring scrubbers makes coal FAR more expensive. Natural gas is really cheap right now so that is largely what is undercutting Nuclear for base load power. It's worth noting that historically natural gas production/use has been far more dangerous than nuclear and far less scrutinized by regulators. [1]http://large.stanford.edu/courses/2018/ph241/wang-k2/ http://large.stanford.edu/courses/2018/ph241/wang-k2/