Decommissioning of JMTR and study for construction of a new material testing reactor

Kaminaga, Masanori; Kusunoki, Tsuyoshi; Tsuchiya, Kunihiko; Hori, Naohiko; Naka, Michihiro

IAEA-TECDOC-1943, p.45 - 56, 2021/02

https://www.iaea.org/publications/14806/sustainability-and-self-reliance-of-national-nuclear-institutions

The JMTR operation was once stopped in order to have a check & review in August 2006, and the refurbishment and restart of JMTR was finally determined by the national discussion. The refurbishment was started from FY2007, and was finished in March 2011. However, at the end of the FY2010, the Great-Eastern-Japan-Earthquake occurred, and functional tests before the JMTR restart were delayed. On the other hand, based on the safety assessments considering the 2011 earthquake new regulatory requirements have established on Decmber18, 2013 by the NRA. The new regulatory requirements include the satisfaction of integrities for the updated earthquake forces, Tsunami, the consideration of natural phenomena, and the management of consideration in the Beyond Design Basis Accidents (BDBA) to protect fuel damage and to mitigate impact of the accidents. Analyses related to the new regulatory requirements have intensively been performed timely, and an application to the NRA had been submitted in March 27, 2015. After submission of application, seismic resistance assessment of JMTR reactor building was carried out by assuming the standard earthquake ground motion of 810 ga. As the results, it was found that seismic reinforcement work for reactor building and reactor pool wall were required. As a result, it became clear that at least 7 years of reinforcement work period and cost of about 40 billion yen are required for seismic reinforcement and to meet new regulatory standards. At the same time, it was made clear that high availability such as 8 operation cycles per year as originally planned cannot be expected due to aiging problem. For this reason, JAEA positioned JMTR as a decommissioning facility in the mid- and long-term plan of JAEA announced in April 2017. On the other hand, JAEA started to study the construction of a new material testing reactor. The examination results will be compiled by the end of FY2019. In this paper, outline of JMTR decommissioning plan is described.