The Japan Atomic Energy Agency (JAEA) said on 3 June it had obtained the permission by the Nuclear Regulation Authority (NRA) for changes to the 30MWt High Temperature Engineering Test Reactor (HTTR) in conformity to the new regulatory requirements. This is the first time a restart permission has been granted for a gas-cooled reactor in Japan.
JAEA said that by employing a high-temperature-resistant and large-heat-capacity graphite core, the high-temperature gas-cooled reactor (HTGR) enables inherent safety characteristic of slow and limited temperature transient without fuel damage (core meltdown) even in a loss of coolant accident. “The safety review by NRA against the New Regulatory Requirements has confirmed that no fuel damage would occur even in the event of a beyond design basis accident such as multiple losses of reactor shutdown functions,” the Agency noted.
The success of having obtained the permission is expected to help the ongoing effort of JAEA in developing an international safety standard that is based on the safety characteristics of the HTGR. Such a standard is also important for HTGR commercialisation. The success is also expected to help strengthen the international competitiveness of Japan`s HTGR technology, JAEA said.
Following the restart of HTTR, a number of activities are planned to be carried out including:
- the safety demonstration tests in the OECD/NEA LOFC project
- discussion on technology demonstration tests of the heat utilisation system consisting of a helium gas turbine and hydrogen production facilities to be connected to the HTTR, operation test of fuel performance
- international cooperation and human-resource development utilising the HTTR.
Further deepening of research cooperation with Poland where HTGR development is being undertaken is also expected, JAEA said.
“To aim to restart the HTTR early while taking countermeasures against the new coronavirus infection, the refurbishments to the HTTR as mandated by the permission of changes to reactor installation will be steadily carried out, including installation of countermeasure systems against internal and external fires and installation of diverse radiation monitoring systems, and so on,” JAEA concluded.
Japan's High Temperature Engineering Test Reactor (Photo: JAEA)