A High Temperature Gas-cooled Reactor (HTGR) is particularly attractive due to capability of producing high temperature helium gas and its inherent safety characteristic. The High Temperature Engineering Test Reactor (HTTR), which is the first HTGR in Japan, achieved the rated thermal power of 30MW and reactor outlet coolant temperature 850°C in December 7, 2001. On March 6, 2002, "certificate of pre-operation test", that is, operation permit of the HTTR at rated operation mode, was conferred from the Ministry of Education, Culture, Sports, Science and Technology.
For safe and steady execution of the test, the rise-to-power test was conducted step by step, that is, it was divided into three phases of the power levels of 10, 20, and 30MW. During the rise-to-power test, 22 tests were carried out such as calibration of nuclear instrumentation system to thermal power, performance of reactor control system, core physics, thermal expansion of high temperature components, radiation shielding performance, fuel and fission product behavior, performance at abnormal transient. All tests planned in the rise-to-power test had been successfully carried out and the performance of the HTTR was evaluated. This report describes the rise-to-power test results of the HTTR.