Duration: 12 months
The proposed study aims development of the new Sr-90 radioisotope fuel to be used for European Radioisotope Power Source (RPS) for the needs of ESA missions as well as potential commercial applications. If successful, the new RPS has potential to break through the current shortage of radioisotope power for deep space exploration and resource utilization. While being largely available in nuclear waste, Sr-90 radioisotope has been used for terrestrial applications but was rejected for space due to heavy gamma-shielding required. Sr-90 undergoes two-stage beta-decay (emitting high-energy electrons) which, deflected by the Coulomb interaction in atoms with high atomic number (Z), cause strong bremsstrahlung radiation in the form of X-rays. The idea is to avoid heavy gamma-shielding by admixing a light beta absorbent into the Sr-90 fuel composition and, therefore, avoiding bremsstrahlung radiation by reducing the effective Z of the fuel composition. In addition, we propose to revise the chemical form of Sr-90 considering SrB6 and some other candidate forms. The study proposes thorough research of the materials, including their thermal, chemical and radiation stability, the aspects of their synthesis and safety during production. We aim to optimise the power-to-weight ratio of the radioisotope fuel with the benchmark goal of 0.1 W/g at the level of remaining bremsstrahlung radiation equal to the one of Am-241 in the form of oxide.
