IIRC those old Belgian reactors got in the way of more renewables for some time. They provided a very cheap base load that seemed hard to modulate, which meant that even cheap renewables couldn't really compete on price. If I understand correctly, newer nukes can more easily modulate their output, which would be useful at night or on days without wind etc. Gas peaker plants currently fill this gap.

> If I understand correctly, newer nukes can more easily modulate their output, which would be useful at night or on days without wind etc. Gas peaker plants currently fill this gap.

It's not new, it's that PWRs have to be built and operated with that capability (load following), which most nations didn't bother with until pretty recently because it does have a cost in complexity & efficiency. But France has done it that way pretty much the entire time.

> Gas peaker plants currently fill this gap.

Nukes with load following aren't peakers: PWRs can modulate output by 2~5%/minute (depending on their exact design and operating mode) between 30 and 100%. They're not reactive enough to compensate for wind, although they can work with the daily and seasonal patterns of solar pretty well.

The replacement for peakers are mostly batteries (hydro and pumped hydro where that's available but usually where available it's already done)