A method which eliminates the radiation damage problem is a Two-Step Photon Intermediate Direct Energy Conversion (PIDEC) method that uses the efficient generation of photons from the interaction of particulate radiation with fluorescer media. The photons are then transported to wide band-gap photovoltaic cells where electrical current is generated. PIDEC holds the promise of 40% energy conversion efficiency in a single cycle. PIDEC can be applied both to large power generation systems and to small scale nuclear batteries based on radioisotopes (Radioisotope Energy Conversion System-RECS).
The direct energy conversion system would be more efficient than current steam cycle systems and would not use water. The system that the University of Missouri and U.S. Semiconductor Corp are developing is mechanically simple, potentially leading to more compact, more reliable and less expensive systems. Mark Prelas is the lead researcher.
A typical light-water reactor nuclear power plant offers thermal efficiency around 35%, while a modern coal-powered plant with super-critical boiler tops out at 44%. New high temperature nuclear reactors could also reach those levels of efficiency.
The latest gas turbines offer thermal efficiencies in the 40% range, with a recent model reportedly obtaining 46%. These values refer to simple-cycle operation, where turbine exhaust is not further used. Real advantage comes from gas turbine exhaust applied as input to a standard steam turbine in a combined-cycle power plant. This is where new-generation gas turbines can become the driving engine to obtain 60%+ overall thermal efficiency.
The Nuclear Energy institute has coverage and has an interesting but wait and see if this can be scaled up or if smaller scale plants can be matched to this technology and if cheaper and more reliable can be made to be true.
There has been other work on direct nuclear radiation to electricity conversion systems and high efficiency thermal to electricity systems.
Background on cooling nuclear powerplants.