There are no emissions from producing electric power, but tons of emissions building the plants and reactors, mining the fissile materials (which in large come from Russia, btw), transporting the materials, etc.

That's technically true, but more a consequence of fossil fuel infrastructure peripheral to the power plant itself. Switch your rail network to full electric and use more electricity in your steel manufacturing (already the predominant modern foundry production technique), you'll solve a big chunk of this problem.

After that you're talking about CO2 produced by setting concrete to build the plant, and that's functionally a push relative to any other power plant that also uses concrete (basically all of them, concrete is popular for a reason). You're also moving well below the carbon emissions targets we need to hit by 2050, so its an efficient move.

it was to stall the phaseout of coal, expand on gas relying on Russia while halting the expansion of renewables and utterly destroying the PV industry

German domestic firms were making huge margins on Russian gas imports right up until the Ukraine War broke out. That's a big problem with fossil fuels. They're still incredibly cheap to mine, with a lot of the cost coming via markups in the retail sector. There's also a huge incentive to simply import PVs from countries with dirt cheap labor costs. So.... mostly China with a bit of Canada thrown in there. Germans, like the Americans before them, no longer want to invest in industrial capital because it has a shit ROI. They want to invest in the FIRE and Tech Sectors, because they've got crazy high returns.

So more and more industrial capital keeps getting dismantled, with imports filling the gap. And nobody really seems to care about what this does to domestic security or capacity in the event of supply chain disruptions, because that's Future Peoples problem and we're making so much money right now.