This is an important point that quickly gets lost in a simplified debate.
Different types of power have different characteristics. Nuclear power plants runs at constant load and changes in power are slow. They take on the order of days to start and stop, and can not on their own follow load changes on a country wide network.
This isn't good or bad, it just is. They can manage the same base load day every day until they need servicing. But that also means you need other power sources to take the top load. That's usually natural gas turbines, even if it could be other things. Hydro is optimal, but most countries have a limited capacity for that. Which is, somewhat ironically, a similar situation as wind and solar have, but for completely different reasons.
Keep that in mind when people talk about replacing natural gas with nuclear. They do different things.
This mostly isn't physics, but rather a reflection of nuclear power's high capital costs. Nuclear plants have demonstrated that they can ramp up and down pretty quickly compared to e.g. most combined cycle natural gas plants.
"For example, according to
the current version of the European Utilities Requirements (EUR) the NPP must at least be capable of daily
load cycling operation between 50% and 100 % of its rated power Pr
, with a rate of change of electric
output of 3-5% of Pr per minute. " - it goes on to discuss how most modern light water plants significantly outperform this requirement.
"Most of the modern designs implement even higher manoeuvrability capabilities, with the possibility
of planned and unplanned load-following in a wide power range and with ramps of 5% Pr per minute.
Some designs are capable of extremely fast power modulations in the frequency regulation mode with
ramps of several percent of the rated power per second, but in a narrow band around the rated power level. "
> Keep that in mind when people talk about replacing natural gas with nuclear. They do different things.
Having some nuclear base load certainly helps, though, if natural gas is disrupted. Instead of having both the dispatchable power and variable power impacted from reduced natural gas supply, you instead only have a portion impacted.
One strategy is to build a bunch of renewable for during the day. Add some nuclear base load. And then with the surplus power you get sometimes, do power-to-gas with electrolyzer cells. Finally, use natural gas peaker plants and burn natural gas where justified in industry. This is a nice diverse mix with storage.
Solar and wind are also inflexible (they generate when sun and wind are out, not on demand). In addition to hydro, natural gas is on demand, which is why we’ve shifted a lot of generating capacity to it. But that makes Europe dependent on Russia and contributes green house gases even if it doesn’t emit much air pollution.
Hydro is even better, you can modify some dam, then pump water back before the dam, storing energy for later usage which make a very cheap energy storage.
Yes, last winter France imported a lot, because more than 4 reactors were shut down for maintenance due to corrosions problems that has been found.
These problem should had been found earlier, and would allowed to make the maintenance before the winter, but due to covid, inspections have been postponed.
For example, 01/11/20 to 26/12/20 (their website allow only 8 weeks period graph) you can see that overall France exported a lot of electricity to other EU countries in the middle of the winter.
rather because a recent change in the energy code allow to count neighbor firm capacities into the adequacy requirement and the usage of monte carlo methods for adequacy requirement.
