Radioisotope Thermoelectric Generator Cooling and Gaseous Nitrogen Purge for Payloads

A radioisotope thermoelectric generator cooling and gaseous nitrogen purge system is installed in Discovery OV-103) and Atlantis OV-104) to support those payloads with RTGs or gaseous nitrogen purging requirements. The water coolant system lines are located in the aft fuselage and payload bay of the orbiters. The water system flows water through the existing ground support equipment heat exchanger in the aft fuselage. The heat exchanger cools the water from the RTGs and directs it back through the RTGs. An accumulator located in the aft fuselage next to the GSE heat exchanger acts as a reservoir to absorb excess water and is pressurized with gaseous nitrogen. The water preflight servicing umbilical is located at X o 835.05.

The gaseous nitrogen purge system connects at the existing nitrogen/oxygen panel at the X o 576 bulkhead. The gaseous nitrogen is directed from the nitrogen/oxygen panel to the existing payload interface panel in the payload bay and provides gaseous nitrogen purging as required by the payload.