USNC-Tech develops deep space propulsion system

23 October 2020

Ultra Safe Nuclear Technologies (USNC-Tech) - a subsidiary of Ultra Safe Nuclear Corporation (USNC) - has developed a design concept as part of NASA-funded research into nuclear thermal propulsion (NTP) systems for potential use in deep space travel. The concept uses a specialised variation of USNC's proprietary fully ceramic microencapsulated, tristructural isotropic fuel, developed for use in power reactors.

USNC-Tech's NTP design concept (Image: USNC)

Nuclear thermal power for spaceflight has a number of advantages over chemical-based designs, primarily providing higher efficiency and greater power density resulting in lower propulsion system weight. This would contribute to shorter travel times and lower exposure to cosmic radiation for astronauts, enabling deep space missions such as crewed missions to the Moon and Mars.

Seattle-based USNC-Tech said advancements in nuclear fuel design and passive safety measures pioneered by parent USNC with its Fully Ceramic Micro-encapsulated (FCM) fuel has enabled USNC-Tech to create a novel NTP concept with specialised performance capabilities. The enhanced safety characteristics and design flexibility of the USNC-Tech concept, it said, is "a critical step forward in achieving extensibility of NTP systems to deep-space missions".

"Key to USNC-Tech's design is a conscious overlap between terrestrial and space reactor technologies," said USNC-Tech CEA Paolo Venneri. "This allows us to leverage the advancements in nuclear technology and infrastructure from terrestrial systems and apply them to our space reactors."

USNC describes FCM as a next-generation uranium oxycarbide tristructural isotropic (TRISO) particle fuel design, replacing the 50-year-old graphite matrix of traditional TRISO fuel with silicon carbide (SiC). It says the result is a safer nuclear fuel that can withstand higher temperatures and more radiation. The SiC matrix in FCM fuel provides a dense, gas-tight barrier preventing the escape of fission products, even if a TRISO particle should rupture during operation.

The new matrix improves the structural and containment characteristics of TRISO particles, trapping and sealing radioactive fission products permanently, preventing contamination of the environment. The higher-thermal conductivity of FCM fuel allows the fuel pellet to have a flatter temperature profile, lowering peak temperatures in nuclear reactors.

The USNC-Tech NTP concept uses a specialised variation of USNC's FCM fuel, which enables "a new family of inherently safe space-optimised reactor designs that ensure astronaut safety and environmental protection".

Using low quantities of HALEU, it says this unique NTP concept delivers high thrust and specific impulse previously only achievable through high-enriched uranium. In addition, use of FCM fuel "leverages pre-existing supply chains and manufacturing facilities used by terrestrial nuclear reactor developers, reducing production risks and enabling sustainable industry involvement".

"We want to lead the effort to open new frontiers in space, and do it quickly and safely," said Michael Eades, principal engineer at USNC-Tech. "Our engine maximises the use of proven technology, eliminates failure modes of previous NTP concepts, and has a specific impulse more than twice that of chemical systems."

Formed in 2019, USNC-Tech is an independently operated and managed subsidiary of USNC.

Researched and written by World Nuclear News