A conceptual design of static converters for small, co-generation modular nuclear power plants is developed and analyzed. Each converter is comprised of an alkali metal thermal-to-electric. conversion (AMTEC) top cycle and thermoelectric (TE) bottom cycle cooled by natural convection of air. In addition to electricity production at a net efficiency in the low thirties, the small nuclear power plants with AMTEC/TE converters could provide co-generation heat for space heating, seawater desalination and/or high temperature process heat or steam. For the potassium AMTEC/TE converter, the conversion efficiency is about 1% point higher, the hot side temperature >100 K lower and the co-generation heat is slightly lower than for the sodium AMTEC/TE converter when operated at the same anode vapor pressure. On the other hand, when operated at the same hot side temperature, the efficiency of electricity production of power plants with K-AMTEC/TE converters could be similar to25% higher, while the co-generation thermal energy for space heating is similar to25% lower than with Na-AMTEC/TE converters. The present analysis showed that K- and Na-AMTEC/TE converters could be sized to produce up to 64 and 81 kW(e) each at hot side temperatures of 1030 and 1150 K, respectively, while achieving >90% total utilization of the nuclear reactor's fission energy for the plant. (C) 2003 Elsevier Ltd. All rights reserved.