The closure won't be speedy. Crews wouldn't finish removing used nuclear fuel from Monju until 2022, and it wouldn't be completely dismantled until 2047. That's 61 years after construction began. Still, it's easy to see why the time might be considered worthwhiel. Japan has already poured over $8.5 billion into the experimental reactor with little to show for it. There's no guarantee that Monju will work as promised even if everything goes according to plan. Also, it's not exactly popular given both the gradual shift to clean energy and ongoing worries about nuclear power's safety following the Fukushima earthquake and tsunami.

Even so, the government could have a fight on its hands. It needs both the approval of the city of Tsuruga and its prefecture to close Monju, and both are hesitant to decommission a reactor in an area that has already been hit hard by plant closures and disasters. They want better explanations and justifications for the shutdown, and there's a concern that the Japan Atomic Energy Agency' safety issues (it omitted inspections at Monju, for one thing) make it a bad candidate for dismantling the plant. The order to close the reactor is a start, though, and we'll know more when a plan is ready in April 2017.