In early 2010, a High-Temperature Engineering Test Reactor (HTTR) in the town of Oarai, northeast of Tokyo, generated a temperature of 950°C that was enough to help produce hydrogen for 150 hours. The Japan Atomic Energy Agency (JAEA) and others thought that a cost and energy efficient way of producing hydrogen had been found. 

Those hopes were dashed in March 2011 when the Fukushima Daiichi disaster led to a shutdown of the country’s entire nuclear power fleet.

After a decade of dormancy, in 2021 the JAEA brought the HTTR project back online, as well as the research. A new milestone was reached in March this year when a safety demonstration test proved that the reactor could cool by itself in case of an accident. This has reignited hopes for nuclear power-based hydrogen production.

High-temperature, gas-cooled reactors like the HTTR have the potential to also add another color to the hydrogen rainbow. While colors like green, blue and gray have been popular in describing, respectively, hydrogen production via renewables, CCS, and fossil fuels, hydrogen produced with nuclear power is labeled as pink.

International competition is one reason why Japan has restarted its program. Poland, the UK and the U.S. all have similar projects. China, however, has made the most progress, launching in December 2023 the world’s first modular high-temperature, gas-cooled reactor nuclear power plant; this HTR-PM features two small reactors (each 250 MW) that uses helium as coolant and graphite as the moderator.

Japan NRG reached out to the JAEA for updates on the HTTR development, funding and international cooperation.