I don't think that's actually true. US Navy and their contracting shipyards had consistently built nuclear subs in 3 year strides for decades. One set of fuel lasts is good for 1/5th century, after that the sub needs to be cut up and refueled. It's not something that take years after years of permitting and change of plans and suspected acts of arson of unknown motivation if it's literally operated by US Army or Navy(but not NASA).

Solar power is just amateures littering compared to that.