RE: Steam Powered Starships?

Well, depending on the kind of radiation you're dealing with, the
photoelectric effect (e.g. photovoltaic solar cells) do just that.
Depending on the material used, they can be effective at a many
different
EM frequencies.

I seem to remember that the new reactors to be used on the International
Space Station were a type that pretty much directly converted radiation
into energy - the Russians were getting pretty good at small reactor
design
& tech before everything went belly up.  Has anybody else heard of this?
Noah