We have old gen II reactors that are being extended, but really should not be. However, there is NO replacement for them.
In addition, there is loads of spent fuel not only at these sites, but others that have been retired.
With transatomic and other companies molten salt approach, we can not only create a reactor that is INCAPABLE OF FAILURE (unless a number of physical LAWS are not true), but, these can burn up the majority of the 'spent fuel'. What will remain will be only 5-10% of the original volume, and will be safe in under 200 years.
Even once we build these (and we will), at some future point, AE combined with FUSION power, will likely become very viable. BUT, it is still better to run these fission reactors to process the 'waste' and turn it safer.