If nuclear is to scale up in India and China then fast reactors and fuel reprocessing need to happen.
There are only enough uranium reserves in the world for like a hundred years of energy consumption, but with plutonium produced by fast reactors this same fuel would provide the world with energy for thousands of years.
Regular LWRs with the regular once through fuel cycle only covert a couple percent of the fuel into useable power, while fast reactors can convert most of it. Like 20x more.
No real need for fast reactors.
With clever engineering possible to reach 1 breeding ratio with light water as well.
Throium is interesting, because the U233-Th232 has better neutron economy than U238-Pu239.
Means reaching 1 breading ratio with Pu239 require fast reactor, without moderator.
U233-Th232 possible with thermal neutrons,with moderator.
I calculated it 15 years ago, actually there are deisng proposals to modify normal light water reactor for closed fuel cycle.
Search keyword:"Radkowsky thorium reactor"
Of course the real problem is how to breed U233 in first place, and of course from USA standpoint anyone having reprocessing capacity means they are days away from nuke.