But your still arguing up the wrong tree
perhaps n dollars have been invested for n-1 return, in conventional fuel rod systems
However, very little effort has been put into the pebble bed reactor.
Doability is more a function of theory and design than practice and implementation. If the theory is there and a reasonable design can be derived from the theory, then is just an implementation question. Its NOT like, say, Fusion research.
Davin L.
