General purpose heat source radioisotope thermoelectric generator program. Book 1: Accident analysis

The status of the accident analysis for the Ulysses outer planetary space science mission is presented. This mission employs a Radioisotope Thermoelectric Generator (RTG) as the prime electrical power source for the spacecraft. The RTG employs silicon-germanium thermoelectric couples to produce electricity from the heat energy that results from the decay of the radioisotope fuel, Plutonium-238, used in the RTG heat source. The heat source configuration used in the RTG is termed General Purpose Heat Source (GPHS), and the RTG is designated GPHS-RTG. The results of a rigorous safety assessment, including substantial analyses and testing, of the launch and deployment of the RTG for the Ulysses mission are given. A summary is given of the potential accident and failure sequences which might result in fuel release, the analysis and testing methods employed, and the predicted source terms. Each source term consists of a quantity of fuel released, the location of release and the physical characteristics of the fuel released. Each source term has an associated probability of occurrence. The purpose is to: (1) identify all potential single or multiple malfunctions during the complete mission profile which can possibly affect nuclear safety; and (2) provide estimates of probabilities of occurrence associated with each type of accident.