MOD-RTG represents the design configuration for the next generation of Radioisotope Thermoelectric Generators (RTG), aimed at improving specific power and efficiency over the current General Purpose Heat Source Radioisotope Thermoelectric Generator (GPHS-RTG). The modular RTG reference design has been described in previous papers (Reference 1). The multicouple is a key element required for the successful development of the modular RTG. The multicouple is a high voltage, thermoelectric device employing a close packed, glass bonded thermopile array of twenty thermoelectric couples, connected in a series circuit. The multicouple is designed to operate a 1270°K hot junction temperature and a 570°K cold junction temperature, yielding a power output of approximately 2.1 watts at 3.5 volts at beginning of life. The multicouple design (Reference Figure 1 ) has also been described in a previous paper (Reference 2).