Permission of changes to reactor installation of the HTTR (High Temperature Engineering Test Reactor) in conformity to the New Regulatory Requirements.
On June 3rd, 2020, JAEA obtained the permission by the Nuclear Regulation Authority (NRA) of changes to reactor installation of the HTTR (High Temperature Engineering Test Reactor, maximum thermal output: 30 MW) in conformity to the New Regulatory Requirements. This marks the first time a restart permission is granted for a gas-cooled reactor in Japan.
By employing a high-temperature-resistant and large-heat-capacity graphite core, 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 present success of having obtained the permission is expected to aid the ongoing effort of JAEA in developing an international safety standard that is based on the safety characteristics of the HTGR and which is important for HTGR commercialization. The success is also expected to contribute to strengthening international competitiveness of Japan`s HTGR technology.
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 heat utilization system consisting of helium gas turbine and hydrogen production facilities to be connected to the HTTR, operation test of fuel performance, and international cooperation and human-resource development utilizing the HTTR. In addition, further deepening of research cooperation with Poland where HTGR development is being undertaken is expected.
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.