Japanese Government Pulls the Plug on Fast Breeder Reactor Monju

Japanese Government Pulls the Plug on Fast Breeder Reactor Monju

The Japanese government formally announced on 21 December 2016 its decision to permanently shut down the 280 MWe Prototype Monju sodium cooled Fast Breeder Reactor (FBR). The reactor, located at Tsuruga in Fukui Prefecture, western Japan, and owned by the Japan Atomic Energy Agency (JAEA), was a central element in the nations plutonium fuel system program, and was intended to form the basis for commercial deployment of fast reactors in the future. After more than two decades Monju had operated a total of 250 days.

Announcing the decision, Chief Cabinet Secretary Yoshihide Suga stated: “We will decommission Monju given that it would take a considerable amount of time and expense to resume its operations.” The government has calculated it will cost at least 375 billion yen (US$3.2 billion) over 30 years to fully decommission Monju, on top of the 1 trillion yen (US$8.5 billion) already invested in the reactor over the past decades. It is proposed to remove the spent nuclear fuel from the reactor by 2022 and finish dismantling the facility in 2047.

Construction of Monju began in Chernobyl-year 1986, and criticality was achieved in April 1994, with grid connection following in August 1995. In December 1995, the reactor suffered a molten sodium coolant fire, which kept it closed until 2010. It operated on limited capacity for three months between May and August 2010, when an In‐Vessel Transfer Machine fell onto the reactor vessel.

A safety inspection of Monju in 2012 showed that more than 9,000 of about 49,000 specifically relevant parts had not received necessary maintenance checks. Subsequently, the NRA recognized seven instances in which Monju operators violated safety regulations, including equipment malfunctions and failure to properly manage documents. In May 2013, the NRA ordered JAEA not to embark on preparations for its restart. In March 2015 the JAEA provided assurances to the NRA that it had implemented reforms, however further revelations had emerged during the previous two years that the agency had violated safety regulations and committed errors by not conducting thorough checks of other pieces of equipment. In November 2015 the NRA declared the JAEA as unfit for purpose and that a new entity would be required to manage the reactor, or, if that proves not possible, take a decision to permanently shut down the reactor. In November 2016, it was estimated that any restart of Monju would take eight years.

Citizen-led legal opposition to the reactor has persisted from the start of construction to the present day. In January 2003, the Nagoya High Court ruled against the reactor, overturning an earlier approval for its construction. This was overturned again in May 2005 by Japan’s Supreme Court. Court action to prevent operation of Monju was still underway at the time of the decision to decommission the plant.

The decision to terminate the Monju project comes at a time when overall nuclear policy in Japan remains in crisis, with two commercial reactors currently in operation, and one in maintenance outage. The government attempted to present the Monju decision as not impacting overall nuclear policy, specifically its plans for spent fuel reprocessing and plutonium Mixed Oxide (MOX) fuel use. “The nuclear fuel cycle is at the core of our energy policy,” said the Ministry for Economy, Trade and Industry (METI) minister, Hiroshige Seko, this week. METI will take over from the science ministry in overseeing the development of potentially more practical fast reactors. “We will make full use of the highly valuable knowledge and expertise acquired at Monju as we move forward with fast reactor development...first by concentrating on creating a strategic roadmap,” Seko said.

In November 2016, the Council on Fast Reactor Development, set up by the Government to propose options for the future of fast reactor development, agreed on the construction in Japan of a demonstration reactor—the step after the implementation of a prototype reactor like Monju. In reality, this is not a new policy, as earlier this decade the Fast Reactor Cycle Technology Development Project was launched with the aim of a design selection and construction of a demonstration 500 MW Japan Sodium Fast Reactor (JSFR) from 2015, with operation from 2025. Even before the Fukushima Daiichi accident, there were no realistic prospects of this reactor being built in the timeframe envisaged. It remains unclear, to what extent Japan will continue or extend its collaboration with France and the ASTRID fast demonstration reactor, design details for which remain unfinished. Japan’s one remaining fast reactor, the experimental Joyo FBR in Oarai, Ibaraki, has remained shutdown since 2007, and it is proposed by JAEA that it restart operations from 2021.

Without a doubt, the decision to terminate the Monju project, long considered a failure and unlikely to ever operate successfully, could have been made years before now. That it was not was in part due to concern that it would raise questions about overall Japanese plutonium policy and have a wider negative impact on nuclear power generation itself. The decision finally has been made, but the questions remain.