Comment by Retric
5 hours ago
Nuclear power plants need to be taken offline for multiple weeks to months at a time for refueling and maintenance over their lifespans making them a poor fit for base load without extremely costly redundancy in a small country.
A couple points. No, entire plants aren't taken offline at once typically, individual reactor cores are, and modern designs work to minimize that. They still maintain extremely good uptime, especially if you're comparing them to intermittent renewables. Secondly, Italy isn't super tiny, and you need redundancy for outages and such in any grid regardless of its components.
A large fraction of all nuclear power stations only have one reactor.
> maintain extremely good uptime
Not from a capacity planning standpoint.
> Nuclear power plants need to be taken offline for multiple weeks to months at a time for refueling
CANDU reactors, for one, can be (and are) refuelled live:
* https://en.wikipedia.org/wiki/Online_refuelling
Every few decades they do need to be refurbished though.
Cutting out the “and maintenance” bit is misleading.
It’s commonplace for maintenance issues at non CANDU reactors to extend the “refelling” downtime. So no, CANDU can’t stay online for decades without maintenance and instead have similar downtime issues. The major benefit is when manufacturing plutonium due to shorter fuel cycles, but overall CANDU reactors are less cost effective which is why adoption fizzled out.
> So no, CANDU can’t stay online for decades without maintenance and instead have similar downtime issues.
There are several situations:
* refuelling occurs
* maintenance and/or inspection needs to happen
* refurbishment may be desired
Some of these things take downtime, some do not, depending on the design of the reactor and other factors. A blanket statement of "refuelling forces a downtime" is incorrect in many situations. Depending on the maintenance (or inspections) needed, this may or may not need downtime. Refurbishment generally means tearing things apart, so usually means downtime, but if a site has multiple reactors they can be done one at a time, e.g.:
* https://news.ontario.ca/en/release/1006993/ontario-delivers-...
Eh, again, I disagree. As an example: Many CANDU reactors have insanely high availability. Example: Qinshan CANDU Unit 1 only had a planned outage of less than 27 days in 2023. There are many other examples. That is crazy uptime in the world of electricity production. And to be clear, if you come at me with "Oh, what about the major maintenance required every 10+ years?". Thermal (coal/gas) has the same issue.
1 reply →
I had a discussion with ChatGPT about this concern. When comparing a modern EPR (European Pressurized Reactor) to a modern coal or natural gas thermal power plant, the required maintenance cycles look fairly similar. For the nitpickers/tomato throwers (I see you!): I am using EPR because it is state-of-the art for nuclear power, and I am specifically using the term "modern" for thermal power plant because the newest ones (China, Japan) are nearly at the frontier of efficiency possible for that type of electricty production.
Roughly: EPR runs for 18 months, then requires 1-2 months of maintenance (which includes refuelling about one third of its fuel assemblies). A modern coal or natural gas thermal power plant runs 12-18 months, then requires 1 month of maintenance.
Next, I could not resist as other commenters already mentioned it. You wrote: "small country". As the Aussies say: Yeah, no. Italy is 300,000 sq km. That is not small. If compared to the United States, it would be the fifth largest state.
Finally, why does it seem that all discussions about electricity production on HN always devolve into the "Base Load Wars"? For me, it is starting to feel like a meme. (Are there LLM troll bots trained to enter HN discussions and make a bunch of "base load" arguments?) Seriously, can someone please create a text-based role playing game that revolves around a future society locked into eternal "Base Load Wars"? (See: PhD Simulator[1])
[1] https://research.wmz.ninja/projects/phd/index.html
But is this the intended maintenance duration, or the actual one? Because the construction of every EPR project has been a disaster. Construction took 20 years in Europe and 9 years in China.
Well, there are only four EPRs in the world. It is too early to say. Frankly, as a non-expert "armchair observer", Finland was dumb for starting the EPR project before the design was finalised.
1 reply →