There isnt a working Thorium reactor. There is just one prototype and we are no where close to develop one indegeniously in near future. But energy needs for our country are growing rapidly. So the need for this 123 agreement.
Manmohan Singh clearly know the energy needs of our huge country. With economy going above 9%, we need energy very much. So there is definite need of already established uranium nuclear reactors. Moving further we have to develop plutonium and thorium based nuclear reactors to be self reliant.