Análise energética de baterias nucleares espaciais utilizando diferentes radioisótopos

Abstract

Alongside industrial development, electrical energy became part of everyday anthropogenic activities as well as fueling big dreams and challenges, such as space exploration. It was in this context of great challenges that the need to use energy batteries arose, more specifically of the RTG (Radioisotopic Thermoelectric Generator) type. Its features, such as long life, no need to recharge (or replace), and linear power delivery, unlike those of lithium batteries, are essential in space exploration. The GTR Batteries basically have two modules: a module containing the thermal source, which is a radioactive material, and another module that performs the conversion of heat into electrical energy through the Seebeck effect. The objective of this work is to theoretically design a RTG battery using radioisotopes with alpha and beta decay with characteristics similar to those of the best RTG battery manufactured so far, the MMRTG, which has a thermal/electrical conversion efficiency of 6.25% and can provide 2000 W of thermal power and 125 W of electrical power at the end of its useful life of approximately 14 years. Different radioisotopes from alpha decay were studied, including 232U, 238Pu, 241Am, 243Cm and 244Cm with half-lives ranging from 13 to 432 years, a high decay energy ranging from 5,414 to 6,168keV, and an energy stored ranging from 2.18 to 2.37×10^9 J/g. For beta decay, radioisotopes studied included 60Co, 90Sr, 106Ru,137Cs,147Pm and 210Pb with half-lives ranging from 1 to 30 years, and an energy stored ranging from 1.14 to 2.37×10^9 J/g. As a result, the masses required to supply each radioisotope’s thermal and electrical power demand, the number of Seebeck modules required for electrical energy generation, the thermal and electrical power with initial and final values, and the costs involved were determined. The results show that nuclear battery projects with beta decay are more technically and economically viable for 90Sr in the SrTiO3 oxide format due to the lower costs presented. On the other hand, for alpha decay, the most viable alternative from a technical and economic point of view is the use of radioisotopes such as 243Cm and 244Cm.