A delegation of engineers from the United States nuclear developer TerraPower, which is backed by Bill Gates, has completed a training program at the Korea Atomic Energy Research Institute (KAERI). This training concludes a 7 billion won ($4.67 million) technology transfer agreement. 

Through this deal, the US company acquired South Korean intellectual property and manufacturing design data for a sodium-cooled fast reactor (SFR) safety testing facility known as STELLA.

“This training is a hands-on international education program organized at the request of TerraPower, a US company pursuing the ‘Natrium’ project, a next-generation sodium-cooled fast reactor (SFR) development project,” said KAERI in a press release.

An SFR is a nuclear reactor design that utilizes liquid sodium as a coolant instead of water. Liquid sodium has excellent heat transfer properties, allowing the reactor to operate at higher thermal efficiency and lower internal pressures. 

The lower operating pressure reduces mechanical stress and minimizes the risk of containment failure, which enhances the safety profile of the system compared to conventional light-water reactors. 

STELLA testing facility capabilities

The acquired STELLA technology is a specialized facility that simulates accident scenarios to validate these safety systems without using actual nuclear fuel. 

KAERI has gathered extensive operational data through this system, specifically mapping how heat transfers and how liquid coolant flows during both normal operations and emergency conditions.

“This training is an intensive full-cycle technology course related to SFRs, ranging from understanding the physical and chemical properties of sodium to measurement and safety management, sodium handling practice, and practice at the SFR prototype reactor comprehensive effect test facility (STELLA-2),” added KAERI.

The technology transfer allows TerraPower to construct and operate its own independent SFR safety testing facility in the United States. This physical infrastructure will directly support the company’s 345-MW Natrium reactor project currently under development in Wyoming. 

TerraPower, which was founded in 2008, received construction approval for the Natrium plant from the US Nuclear Regulatory Commission in March. The data acquired from KAERI will assist in validating the safety parameters and coolant mechanics of the Natrium design for US regulatory frameworks.

South Korean institutional cooperation

In South Korea, the state-backed public-private advanced reactor export infrastructure program originally planned to invest 29 billion won in SFR development between 2025 and 2028. However, the National Assembly reduced the 2025 budget by 90 percent, cutting it from 7 billion won to 700 million won, as reported by The Korea Herald.

Although the government restored the funding to 7 billion won this year, the budget disruption delayed the development timeline by approximately one year, pushing the project completion date back to 2029.

“This training is significant in that it is a field-based international education program that shares sodium system design and operation experience on an actual facility basis,” concluded Jeong Ik, Head of the Nuclear Education Center at the Institute. 

“We also expect it to contribute to strengthening continuous technical exchange and cooperation networks between the Institute and TerraPower.”