The decision to close them was purely political as an overreaction to Fukushima.
Yes and no. The og plan was made before Merkel. Merkel slowed the trasition down. But suddently Fukushima hit and the anti nuclear greens had good chances in the upcoming state election. So she closed the powerplans in hope to win an election but the plan was to shut them down anyway but now with less renewables than there should be.
Most nuclear plants operate in a perpetual state of "well we could shut it down with this plan here but we might as well pay more to keep it running since it’s already there. "
They’re like NASA projects: the project timeline is projected to underdeliver because the worst part about these projects is the initial approval and construction cost: once it gets approved, it’s more economical to keep it running than to shut it down and find an alternative.
the running costs also exceed the costs of renewables as the waste issue remains unadressed.