Last year, power escalation testing of Japan’s High Temperature Test Reactor began and a power level of about 16MW on 3 July. However, the reactor tripped on 8 July due to a signal from one of the helium circulators.

The plant remained shut down for the rest of the year, first to find the basic cause of the trip, and then to carry out the first annual inspection/maintenance outage.

Testing has now resumed, and a power level of 20MW is expected to be reached on 2 February. The power will be kept at 20MW for several days to collect data and the reactor will then be shut down for a short time. During this phase of testing, all heat is being rejected through the primary coolant helium/water heat exchanger. In the next phase of testing, due to start in mid-February, the power will again be kept at 20MW, but this time the He/He intermediate heat exchanger will be put in service. This heat exchanger has a rating of 10MW, and during the February tests, the heat will be rejected through both this heat exchanger and the primary coolant water cooled heat exchanger. The gas outlet temperature will be about 600°C.

Testing of the intermediate heat exchanger is an important step as this is the route through which heat will be extracted when chemical processes are being tested at a later stage.

In April, the power will be increased to the rated output of 30MW, and the temperature will be increased to 850°C. These tests are scheduled to continue until the end of June.