High-temperature engineering test reactor


The high-temperature test reactor is a graphite-moderated gas-cooled research reactor in Oarai, Ibaraki, Japan operated by the Japan Atomic Energy Agency. It uses long hexagonal fuel assemblies, unlike the competing pebble bed reactor designs.
HTTR first reached its full design power of 30 MW in 1999. Other tests have shown that the core can reach temperatures sufficient for hydrogen production via the sulfur-iodine cycle.

Technical details

The primary coolant is helium gas at a pressure of about 4 MPa, the inlet temperature of 395 °C, and the outlet temperature of 850–950 °C. The fuel is uranium oxide.