A design concept for a nuclear thermal propulsion (NTP) reactor to power future astronaut missions to Mars has exceeded key performance parameters and optimised the reactor for manufacturability, General Atomics Electromagnetic Systems (GA-EMS) has announced. The reactor's features include a compact core thanks to the use of high-assay low-enriched uranium (HALEU) fuel.

NTP systems pump a liquid propellant - such as hydrogen gas - through a reactor core. The heat released by uranium fission heats the propellant, converting it into a gas, which is expanded through a nozzle to produce thrust. According to the US Department of Energy NTP rockets are more energy dense than chemical rockets and twice as efficient. They also offer greater flexibility for deep space missions, and could reduce travel times to Mars by up to 25%, although chemical rockets would still be used to launch missions from Earth's surface as NTPs are not designed to have sufficient thrust to do this.

GA-EMS President Scott Forney said the company is uniquely positioned to develop and deliver a cost-effective, safe NTP reactor system to progress future space missions. "This is an exciting effort that directly aligns with our 60+ years of nuclear energy research and development, including nuclear reactor design and deployment and our expertise in space systems," he said.

The GA-EMS NTP reactor concept was delivered in response to a NASA-funded study managed by Analytical Mechanics Associates. It leverages advancements in modern nuclear materials and manufacturing methods with experience from the company's involvement with the 1960s NASA Atomic Energy Commission Project Rover - one of the first programmes to demonstrate the feasibility of space-based thermal nuclear propulsion - the company said. GA fabricated some 6 tonnes of nuclear fuel kernels for that project, and was also directly involved in nuclear fuel testing and characterisation for the SNAP-10A reactor, the only US nuclear power reactor launched into space up to now.

According to World Nuclear Association, SNAP-10A was launched in 1965 and powered a satellite for 43 days before being shut down because of a malfunction in a voltage regulator, which was not related to the reactor. It remains in orbit. Russia has used over 30 fission reactors in space.

"NTP systems for NASA Human Mars Missions are achievable in the near-term, and our solution takes advantage of cutting-edge advances, especially with nuclear fuel and high temperature ceramic matrix composite materials," said Christina Back, vice president of Nuclear Technologies and Materials at GA-EMS. "By applying modern science and engineering methods, GA-EMS is reducing risk in space NTP technology development and rapidly advancing the state-of-the-art."

Radioisotope thermoelectric generators - such as the Multi-Mission Radioisotope Thermoelectric Generator that will power NASA's Perseverance Mars rover, which successfully launched from Cape Canaveral in Florida in July - have been used to power US space work since 1961. Unlike NTP, these systems do not rely on nuclear fission, instead converting heat from the decay of plutonium-238 into electrical power.

Researched and written by World Nuclear News