Something you might wish to read: Bettencourt LMA, Trancik JE, Kaur J (2013) Determinants of the Pace of Global Innovation in Energy Technologies. PLoS ONE 8(10): e67864. doi:10.1371/journal.pone.0067864
Interesting how there is no correlation between funding levels for nuclear R&D and patent filings. It must be incredibly expensive to do nuclear research. Bob Wilson