Investigation on the use of Americium Oxide for Space Power Sources: Radiation Damage Studies

Abstract

Within Europe 241 Am is a feasible alternative to 238 Pu that can provide a heat source for radioisotope thermoelectric generators (RTGs) and radioisotope heating units (RHUs) to be used in Electrical power sources used in outer planet missions. In the EPSO-SPACE* project developed as an exploratory research at JRC, a new type of nuclear power source, to provide heat and electricity for deep space missions is considered. It will consist of a 241 Am based compound with aerogel thermal insulation and thermocouples in close contact with the heat source. The assembly is inside an iridium encapsulation to withstand all relevant accident scenarios. The design will be modular and combinable for required electrical output. Several candidate Americium compounds will be investigated for chemical stability at high temperature and for self-irradiation damage. New thermo-electric converter materials containing actinides will be assessed, and a robust encapsulation designed. Safety analyses will be performed including launch explosion and re-entry accidents. The research will conclude in a conceptual design of a prototype power source. In the first part of this study, americium dioxide will be considered from the point of view of its chemical durability and of its behavior against radiation damage and helium formation, two aspects to be carefully investigated due to the high alpha-activity of the americium. Transmission electron Microscopy (TEM) and helium thermal desorption spectrometry (TDS) experiments will be described and results on aged (more than 30 years) AmO 2 reported. Some comparison with 238 PuO 2 based RTG's will be discussed.

Optimization of Uranium-Doped Americium Oxide Synthesis for Space Application

“…In the present study, we propose the doping of americium oxide to stabilize the cubic structure during reductive sintering in order to solve the different problems cited above. Fluorite structured materials are known to have a high tolerance to alpha damage. − Uranium shows a very peculiar behavior when mixed with different trivalent oxides, namely a charge compensation phenomenon as a result of which oxidation of uranium over the oxidation state IV occurs even during reductive sintering. − This phenomenon helps the stabilization of the cubic phase solid solution even at low uranium concentrations. , Uranium–americium mixed oxides have been extensively investigated in recent studies, − mainly due to their potential use as a minor actinide-bearing blanket fuel in nuclear reactors for americium transmutation. However, most of these studies focus on americium concentrations from 10 to 50% (metal base ratio).…”

Promethium: To Strive, to Seek, to Find and Not to Yield

“…Pm batteries can be used in cases where other kinds of batteries would be extremely heavyweight, e.g., satellites or space probes (Vl, 1956 ). Radioisotope batteries are usually either thermoelectric (containing Pu or Am) (Wiss et al, 2017 ) based on the heat generated from radioactive decay, or betavoltaic (alphavoltaic) based on electron/hole pair generation in a semiconductor (such as 147 Pm or other isotopes like tritium or 63 Ni) (Gale et al, 1975 ; Purdy, 1986 ; Spencer and Chandrashekhar, 2013 ; Murphy et al, 2019 ; Xue et al, 2019 ). Betavoltaic batteries, compared with thermoelectric batteries (Matheson, 1975 ), are characterized by a smaller size and a more reasonable price.…”

Chemical bonding in americium oxides probed by X-ray spectroscopy

“…Furthermore, the assessment of the properties of MOX as the multicomponent systems requires a comprehensive knowledge of properties of each binary oxide. The americium oxides and the MOX material with Am are considered as efficient power sources for missions into deep space [1][2][3] . That also requires detailed studies of oxide properties to help with the evaluation of their long-term performance.…”