National Nuclear Laboratory

Americium in space power systems

Developing new nuclear fuel for space missions

It was 2009 when the European Space Agency (ESA) put out an international call asking for partners to develop the technology for the next generation of space exploration. NNL answered that call with a commitment to discovering and developing a power source.

Nuclear fuel, through radioisotope power systems (RPSs), remains the only way to power long term, long distance missions where the sun doesn’t shine. At the time, the nuclear option was Plutonium 238. The downside of that for ESA, is that all the Plutonium is owned by the United States and Russia, meaning ESA was unable to develop and control its own space missions. Finding an alternative would give ESA independence and make space exploration more affordable.

NNL joined a team to carry out an initial scoping study. The research team discovered that as the plutonium from used nuclear fuel decays it forms another radioisotope – Americium 241. The Americium 241 is a heat producing radioisotope that has similar properties to the Plutonium 238 used in RPSs.

Not only that, but Americium 241 has a half life of around 430 years compared to around 90 years for Plutonium 238, making it more suitable for long duration missions. And, as there are over 100 tonnes of civil separated plutonium in the UK alone, Americium 241 offers the potential to be a long-term, sustainable, European energy source.

Having identified the appropriate alternative radioisotope and proved its viability as a power source for space travel, NNL’s innovation has given ESA the confidence it needs to commit to a specific mission. It is now aiming to launch a lunar mission towards the end of the 2020s, meaning the next generation of European moon landings could take place within the next decade.

Over the coming years, NNL will continue to work with ESA to develop a sustainable production process for the supply of Americium 241 while working with other partners who are developing the rest of the technology to ensure the highest levels of nuclear safety at launch and throughout the lifecycle of the project.

For the team behind this stellar innovation, it’s incredibly exciting to imagine the product of their research flying off this world by the time NNL turns 20.