This document addresses basic configurational tradeoffs associated with the SP-100 class of nuclear space power systems. In the SP-100 project, the three reference designs, fallback, baseline, and advanced, employ thermoelectric power conversion with different thermoelectric materials. This issue of the document presents results generated for the thermoelectric design as of the end of 1985. Emphasis is placed on showing general trends and the range of possibilities that could result from selection of a particular design. This document, which reflects efforts on 100-kWe reference designs as of the end of 1985, will be extended and updated to reflect progress in the design studies of the follow-on ground engineering phase for which a 300-kWe size has been selected. THere is a considerable flexibility to the SP-100 power system so that it will generally be most advantageous to tailor it to meet user requirements.