How Jimmy Carter of you. Actually, I like the proposal and agree that it would have been a better expenditure of 500 Billion federal dollars, but...
Such a program would have had at least 75% of the public approval
The very highest poll number I have seen for nukes is 59% (Gallup, 2009). And most polls put it at about low-fifties or lower, so it's not certain that you'd have instant congressional approval.
it's not just a nuke plan, but a natgas/nuke plan using nuke for electricity and natgas/electricity for transportation.
i think if the American people understood what the benefits were to spending $500-$700B (our yearly foreign oil bill) within the U.S., instead of sending $500-$700B overseas to unfriendly governments, they would come around in short order. It would be like a $500-$700B yearly stimulous while helping to keep oil dollars out of the hands of our enemies.
if something better comes along in the future, then you use this lessons learned from this plan to do the next conversion.