Monju is a Japanese sodium-cooled fast reactor, located in Tsuruga Nuclear Power Plant, Fukui Prefecture.. Monju is a sodium cooled, MOX-fueled, loop-type reactor with three primary coolant loops…The reactor has been inoperative for most of the time since it has been built [due to accidents and resulting public suspicion]. On December 8, 1995, the reactor suffered a serious accident. Intense vibration caused a thermowell inside a pipe carrying sodium coolant to break… [T]he sodium was not radioactive. However, there was massive public outrage in Japan when it was revealed that Power Reactor and Nuclear Fuel Development Corporation (PNC), the semigovernmental agency then in charge of Monju, had tried to cover up the extent of the accident and resulting damage. This coverup included falsifying reports and the editing of a videotape taken immediately after the accident, as well as issuing a gag order that aimed to stop employees revealing that tapes had been edited.
On 16 February 2012 Nuclear and Industrial Safety Agenbcy reported that a sodium-detector malfunctioned.
On 30 April 2013 an operating error rendered two of the three emergency generators unusable
On Monday 16 September 2013 before 3 a.m. the data transmission of the reactor stopped to the government’s Emergency Response Support System.
Excerpts from Wikipedia
A panel of experts set up by the Education, Culture, Sports, Science and Technology Ministry has begun discussions on what should be done about the Monju reactor. The panel is expected to reach a conclusion by the summer 2016. Since 2012, the Nuclear Regulation Authority (NRA) has repeatedly conducted on-the-spot inspections of Monju, which is now operated by the Japan Atomic Energy Agency (JAEA). Every time these inspections were conducted, however, they have identified faulty maintenance checks of the reactor and others that violated related laws and regulations.,Monju’s maintenance and inspection program was drawn up in 2009. What is a serious issue is the program had a large number of defects.About 50,000 pieces of equipment must be inspected at the reactor. Without a carefully thought-out plan, these inspections will be far from smooth. It is crucial to review the maintenance and inspection plan, which is the foundation for ensuring safety…
Under the government’s Strategic Energy Plan, Monju is considered a key research base to reduce the volume of nuclear waste. The development of nuclear reactors similar to Monju is under way in Russia, China and India, as uranium resources can be effectively utilized with the fast breeder reactor. Can Japan afford to stop development of the fast breeder reactor and let these countries lead the way? This is indeed a crucial moment.
New organization needed to regain public trust in Monju management, The Yomiuri Shimbun, Jan 18, 2015