Building new nuclear power plants makes relatively limited sense. Currently in many places the costs for wind-power or PV is considerably lower than for new nuclear. Even considering the need for some (e.g. 25%) storage new nuclear is hardly competative.
...
Germany had to bring back some old coal power-plants last year. But this was not so much because of shutting down the German reactors, but because quite a lot of the French reactors were down for lack of cooling water and delayed maintainance.
So, nuclear is so uncompetitive that it makes more sense for France to sell lots of nuclear power to countries, who pretend to be green while opening up new coal mines and hiss enthusiastically at nuclear powered countries.
As to the deployment, see:
https://radiyozh.substack.com/p/how-long-does-it-take-to-build-a-nuclear-reactor-c2a0c6b29116 . Yeah, we can't have
new ones tomorrow, but we can have them in a reasonable time frame.
Even assuming your assumptions that only Japan is capable of creating new reactors was true (which it is simply not), then the solution is not saying "Oh bother" and proclaiming it impossible, the solution is for the EU to actually commit to something. And I mean really commit. Can you honestly say that a quicker buildup would be inconceivable?
As to waiting for for fusion, well, I'm all for researching it, but not at the expense of advancing nuclear. And certainly not waiting for it to become actually usable. When it's actually here and usable and the fuel issues are solved, sure, go for it. Until then we have something that works.
Also, large scale fusion (assuming we crack the issues with, pretty much everything, fuel included) will suffer from a number of the same problems as conventional nuclear. Not all of them, but it wouldn't be a magic solution.
I would consider calling for building new reactors now as a bad idea - it comes with a risk, too late and at high (hardly competative) costs.
2) Having many reactors of the same / similar type is a risky situation. The safety concepts usually call a prompt shut down if a problem with the design is found (e.g. like with the BWRs in Fukushima). Taking safety serious may than cause a black out. So one has to choose between safe or dependable. Given the hard choices and reaction after Fukushima (delaying safety upgrades to keep the reacrtor running) one can not really trust the promissed safety.
3) For a world wide large scale expansion of nuclear power the uranium reserves get critical and the fuel would get more expensive. It would at least need reprocessing of used fuel and this did not work out economically.
A randomly fluctuating power supply in a continent wide grid without some stable power generation can also lead to blackouts. As to trusting promised safety, I actually trust them.
As to the fuel, you mentioned that it's pointless to wait for the new types of reactors - the reactors that could use more types of fuel or use the existing stuff far more efficiently. The theoretical concepts and practical proof-of-concepts actually exist, but yeah, lets wait for fusion, which has been just 20 years away for the last 60 years, because by George, we shall crack it this decade!
edit:
Sorry, need to add:
So they would be down for 1-2 years anyway. In hind-sight it may have been better to keep the reactors running for longer, but that decision point was some 5-10 years ago. All plans are made to shut them down.
...you do know how plans work, right? They can be cancelled or amended based on changes to the situation. Just because someone makes a plan to commit suicide and buys the rope, doesn't mean they need to get up on the chair.
What you are describing is a bureaucratic inconvenience rather than a physical problem. Yes, at this point it would be harder to continue to have them operating, but extremely far from impossible and it would be definitely easier than to dismantle the whole thing.
But yeah, please, continue to virtue signal and do continue with your prolonged twitch reaction to Fukushima.