Radioisotope Power Systems for the European Space Nuclear Power Program

Plutonium and Americium Aluminate Perovskites

“…Therefore, numerous space missions have exploited the decay energy of plutonium-238 for heat or electricity production using radioisotope heater units (RHUs) and radioisotope thermoelectric generators (RTGs). − However, 238 Pu is very expensive to produce and suffers from shortages . For this reason, the European Space Agency (ESA) is exploring the possibility of using americium-241 instead of 238 Pu for future space missions. − To be introduced in a RHU or RTG, americium has to be present in the form of a stable ceramic . For this purpose, the use of pure americium oxide does not seem appropriate due to phase instabilities. − Therefore, alternative americium compounds are being investigated, for example, americium aluminate.…”

Thermoelectric materials for space explorations

“…This shift from 238 Pu to 241 Am is part of the European Space Agency (ESA) program since 2009 to develop new types of TEGs compatible with the power output of 241 Am. 8 Due to the radioactive nature of the isotopes used in RTGs, it is essential to shield electronic components from radiation, especially gamma radiation. This protection is accomplished by employing materials such as Pt, Rh, and Pt-Rh based alloys,…”

“…In contrast, the European space program opted for americium-241 ( 241 Am) instead of plutonium-238 ( 238 Pu) due to concerns about the latter's scarcity and price. [7][8][9] The design of RTGs requires careful consideration of various factors, including preventing device degradation during extended service missions, 10 minimizing the total weight of the devices, 11 and using segmented TEGs to optimize output power and ensure proper operation under specific circumstances. [12][13][14] Furthermore, a critical aspect of RTG design is the accommodation of the TE materials for energy generation.…”

Nuclear batteries: Current context and near‐term expectations

“…18 The European Space Agency (ESA) funded in 2009 a programme aiming to produce in Europe all the building blocks of a radioisotope power systems, developing radioisotope heater units (RHU) and RTG based on 241 Am as heat source. 32 The configurations of the 241 Am-based heating and thermoelectric units have been designed to achieve a 3 W th output for a 200 g RHU and an electrical power output of about 10 W e for a 10 Kg RTG. 7 The European capabilities in powering space programmes by RPS have been recently further implemented by investigating the behaviour of the fuel systems in various accident scenarios.…”