> That’s not what decommissioning means
The word apparently means whatever the responsible authorities want it to mean.
> How, by your definition, would you decommission the coal and gas plants
We used to make gas by heating coal with steam; the result was a contaminated site, coal gas, and coke for steel. But the site was left contaminated with chemical waste - stuff that can in principle be chemically denatured, or buried fairly safely. Thing is, I'm against making new coal-to-gas plants, as much as I'm against new nukes.
I don't have to defend coal and gas power plants; I don't have to explain how to reverse their effects; I'm against building any new ones, and my lack of any remedies for the effects of plants built before I was born doesn't invalidate my stance.
[Edit] I think I missed your point, which was probably based on my use of the word "reversing". You're effectively asking me how to complete the decommissioning of plants that were put out of use before I was born. If you want childish, that's childish: you're asking me for a proposal for reversing climate change.
I'm talking about how to build a nuclear power plant that can be properly decommissioned, in the sense that there's no persistent environmental pollution, and the land can safely be returned to normal uses, such as agriculture and residential housing. I'm against repeating the mistakes my grandparents made, in all their ignorance.