Mitsubishi Heavy Industries Ltd (MHI) has been selected as a core company for the design, production and installation of a new research reactor in a project led by the Japan Atomic Energy Agency (JAEA). Under a basic contract signed between MHI and JAEA, MHI is contracted by JAEA to handle all work related to the development of the new research reactor, and to begin construction.

Japan's Cabinet decided in December 2016 that government policy on the Monju fast breeder prototype reactor in Tsuruga City, Fukui prefecture would shift to its closure and installation in future of a new research reactor at the Monju site. The conceptual design and operation of the new research reactor were then discussed by three key institutions selected by the Ministry of Education, Culture, Sports, Science & Technology. These were JAEA, Kyoto University and the University of Fukui.

It was decided that the new reactor would be used for research & development and personnel training, led by JAEA. This would include fundamental research using neutrons, research & development on safety, use of nuclear energy for innovative technologies and medical treatments, and education.

For JAEA, this is the first opportunity to build a plant since the high temperature engineering test reactor (HTTR) opened in Oarai Town in the Higashiibaraki District of Ibaraki Prefecture in 1998, and building of this new research reactor is a crucial project for the agency.

MHI noted that it has already completed many construction projects for atomic energy plants, including construction projects and renovations to meet new regulations for a total of 24 pressurised water reactors (PWRs) around Japan. MHI played a leading role in the construction of the HTTR and has extensive knowledge and a strong track record in areas from power reactors to research reactors. MHI also oversaw the shutdown of Monju, and is able to coordinate the development of the new research reactor with the schedule and area of Monju's closure to ensure that the construction process is carried out smoothly.

The 280 MWe Monju suffered a series of accidents that eventually led to cancellation of the project. Monju was shut down in 1995, just four months after it began operation when about 700kg of liquid sodium leaked from the secondary cooling loop. Although there were no injuries and no radioactivity escaped plant buildings. JAEA tried to conceal the scale of the damage.

Monju restarted in May 2010 but refuelling equipment fell into the reactor vessel during a refuelling outage later that year, and it has not operated since. Although the equipment was retrieved and replaced, NRA did not allow the reactor to restart. In November 2015, following concerns over lax equipment inspections, NRA determined JAEA was not competent to operate the reactor, and in December 2016, the government decided to decommission it. The JPY1000bn ($9bn) Monju operated for only 250 days since its start-up in 1994.

Image: Illustration of new research reactor facility (courtesy of JAEA)