That was an interesting paper--I didn't realize that Mo-99 was so important for radiotherapy. It sounds like the photofission concept could work--it just requires a big yet modestly high-energy electron LINAC, and plenty of cooling water for the photon converter (electron beam target,) and plenty of cooling water for the transmutation target (the natural uranium target.) It amazes me (I guest it shouldn't, but it does!) that they are talking about 750KW+ of 16-20MeV gamma-rays as the photofission driver...

3/4 of a MW of gamma-rays--man, that is some power there...

I sure wouldn't want to be near this thing when it is operating--atleast not without my 12 ft thick water filled sunglasses and my SPF 10^12!