Meeting participants at the project review group and management board meetings
Participants in the NEA joint project Loss of Forced Coolant (LOFC) discussed key experimental findings on 10-11 March 2025 during a meeting hosted by the U.S. Nuclear Regulatory Commission (NRC).
The LOFC joint project, which first started in 2011, has now been extended to run until 2027. The extension allowed for the reactor restart after modifications which were implemented following the 2011 Great East Japan Earthquake and to perform further analytical work.
The High-Temperature Engineering Test Reactor (HTTR) allows researchers, engineers and other experts to explore reactor performance under non-standard operational conditions. It is modelled on a high-temperature gas-cooled reactor (HTGR) and serves as the only experimental HTGR available amongst the Agency’s member countries.
Capable of reaching temperatures up to 1600°C in certain transient conditions, the HTTR provides essential data for evaluating the inherent safety of this advanced reactor type. The project has so far successfully completed three LOFC test cases designed to assess reactor inherent safety behavior during loss of forced cooling events without SCRAM:
- 9 MW LOFC with vessel-cooling system (VCS);
- 9 MW LOFC without VCS;
- 30 MW LOFC with VCS.
A video of a LOFC test (footage provided by and copyright belongs to the Japan Atomic Energy Agency (JAEA)):
With its graphite-moderated, helium-cooled system, the HGTR offers a high-temperature steam supply, making it attractive for applications such as power generation, hydrogen production and high-temperature heat supply. It is also a technology that is being considered for use in small modular reactors.
These experiments contribute valuable data for safety demonstrations of innovative nuclear technologies. They are particularly important for the verification and validation of computational codes that simulate HTTR thermal-hydraulic behavior.
