"So what are you basing your views on that new nuclear has to or should be part of the mix?"My position is that nuclear energy should be part of the mix.
That said, I've struggled for years before arriving at that position. I say that as someone who once worked on the surveillance side of nuclear energy, my job was (as part of a team) to ensure that nuclear power plants/industry were safe and that nuclear materials were safely secured and not diverted for nefarious purposes.
It is just not possible for me to fully justify my position here as it would require a full-length blog to do so. I will say however that my above comment was based on a number of factors, the first is that despite some recent progress in fusion it won't be a viable option for decades. Second, the demand for power is increasing exponentially, as I've mentioned elsewhere (_ph_), we've been perpetually on the edge of just having enough power with precious little in reserve for many decades when in fact we really need much more energy than we have now (unfortunately, again, I cannot do full justice to that point here).
Third, this story—at least at face value—shows how nuclear reactors could be installed safety and quickly and at a significantly lower cost than traditional above-ground ones.
I'd suggest you watch Sabine Hossenfelder's YouTube post on the problems and high costs of constructing of nuclear power plants in the present political climate. Essentially, I agree with her position but I'd point out that her video was made before this 'underground' proposal (personally, I've held the view for years that deeply-buried nuclear plants—if constructed property and with safety in mind—would be a pretty good solution in respect of all three key factors: cost, safety and speed of construction: https://m.youtube.com/watch?v=5EsBiC9HjyQ.