[hannob]

4th generation nuclear does not exist yet. Building a nuclear reactor just with existing tech can easily take a decade. Building a nuclear reactor that has never been built before with a completely new concept will take at least another decade to develop from a concept to a real working thing.

Even in the case that any of the concepts discussed as 4th generation nuclear will work at all (there's a whole number of previous "new nuclear" concepts that have been tried and never went anywhere), it won't matter in the time most crucial for climate mitigation.