[lven]

Not exactly. Nuclear reactors have a difficult time following the load because of Xenon poisoning. Xenon generated during the fission reactions absorbs neutrons that could have been used for fissions. Luckily, it decays away over time. If you turn down the reactor power, you have to wait hours or day for for Xenon buildup to decay so that you can turn the reactor back on. Some reactors manage to load follow more easily by adding lots of excess reactivity (more potent control rods) which is less safe overall. Smaller reactors will have the exact same issue. The amount of Xenon poisoning is proportional to the power density. NuScale reactors run at even higher power density than normal light water reactors, so they will have even worse Xenon poisoning. They won't be load following. One exception where this isn't true is micro gas-cooled reactors that have so low a power density that they have negligible xenon poisoning and can follow loads easily if necessary. Even then, it's not a great idea because of thermal cycling issues.

[panick21_]

Some reactors can also more effectively let xenon escape. That is one of the reasons why Alvin Weinberg wanted a liquid molten salt reactor, you can let the xenon bubble out like CO2 in a soft drink.

[pfdietz]

And if you do that, then the 137Cs ends up in the off gas storage rather than in the molten salt. A good fraction of the fission products escape the salt, which kind of shoots down one of the main selling points of MSRs.

https://gain.inl.gov/SiteAssets/MoltenSaltReactor/Module2-Ov... (see slide 23)

[Manuel_D]

Nuclear can modulate it's output by more aggressively cooling the water. There's no xenon poisoning since the reactors output is the same. This is undesirable because it's essentially wasting fuel, by deliberately reducing the efficiency of the steam turbine. But it can be done, and fuel is not a big driver of nuclear cost.

[ncmncm]

Modulating nukes' output make each kWh even more expensive, when they are already not competitive.

[nobody9999]

I may be missing something important here, but I'm not a nuclear fission SME. Please do correct me if I'm not making sense.

Doesn't the modularity (multiple 60MW reactors in a single installation) in the NuScale design obviate the "Xenon poisoning" issue, since shutting down one or more reactors doesn't mean halting power generation as it would with a single, larger reactor?

Presumably the reactors can be shut down and powered up independently so addressing the "Xenon poisoning" issue should be just a matter shutting down, then powering up some fraction of the reactors, scheduled to maintain the base load required, no?

[projektfu]

I mean that loads can be shared geographically and the reactors can maintain relatively consistent output.