This study presents several methods to evaluate the exergy of thermal and nuclear radiation. First, a general treatment is developed for the thermal radiation exergy flux. Second, the exergy of thermal radiation is derived from a simple, general, original thermodynamic argument. Third, the state of the art concerning the accurate upper bounds for the conversion efficiency of thermal radiation into work is briefly presented. Fourth, the exergy of nuclear radiation is derived.
Keywords: radiation exergy, thermal radiation, blackbody radiation, diluted thermal radiation, nuclear radiation, nuclear energy, nuclear power