Operation of HTTR

Abstract The first criticality of the high temperature engineering test reactor (HTTR) was achieved on November 10, 1998. After improvement of the reactor system and performance confirmation, the rise-to-power test was started in September 1999. The HTTR achieved the full power of 30 MW at a reactor outlet coolant temperature of about 850°C in December 2001, and the reactor outlet coolant temperature of 950°C was achieved in April 2004. After that, various operations such as high temperature operation at 950°C and safety demonstration tests were conducted until December 2010, and the HTTR has been suspended since the Great East Japan Earthquake in 2011. The high temperature operation at 950°C showed that the HTTR has enough performance to supply high temperature heat to a heat utilization system such as a hydrogen production system. Furthermore, the inherent safety of HTGR was confirmed by the safety demonstration tests.