Radioisotope thermoelectric generators and the role of MOX-fueled lead-cooled fast reactors in isotope supply: a literature review and production analysis

This report explores the potential of advanced nuclear systems for supporting the supply of radioisotopes used in Radioisotope Thermoelectric Generators (RTGs). RTGs are compact and reliable power sources that convert heat from radioactive decay into electricity via the Seebeck effect, making them ideal for long-duration missions in space and remote environments. The report reviews RTG fundamentals, including their operating principles, performance metrics, fuel requirements, and historical development. Building on this foundation, the study investigates the feasibility of producing RTG relevant isotope – Pu238 , Am241, and Sr90 – in a Lead-cooled Fast Reactor (LFR) fueled with Mixed Oxide (MOX). Through parametric analysis of location, fuel composition and power of the reactor, the impact of local neutron flux and spectrum on isotope yields is assessed. The objective is to identify optimal configurations that maximize desired transmutations while minimizing competing reactions. The results demonstrate that LFRs could play a valuable role in enhancing the availability of isotopes for RTGs, contributing both to space exploration and advanced fuel cycle strategies.