The assessment is based on the estimation of the fusion device plasma properties using a simple point model, on general energy balance considerations for hybrid reactors for power generation, and on the estimation of expected performance of a specific type of hybrid reactor-a natural uranium fueled, light water moderated breeding hybrid power reactor driven by a semi-catalyzed deuterium fusion neutron source. Beam-driven semi-catalyzed deuterium and D-T fusion devices for hybrid power reactor applications are compared, and potential advantages of the former are identified. It is found that the plant efficiency of hybrid power reactors driven by a semi-catalyzed deuterium neutron source might exceed that attainable with a D-T neutron source when the fraction of the fusion neutrons that reach the blanket is smaller than about 0.8. A beam-driven deuterium fusion device can be operated in the semi-catalyzed mode and provide an intense source of neutrons even for plasma electron temperatures as low as 5 keV. Such a fusion neutron source might be useful for experimental facilities.