France, which is at the forefront of MOx conversion efforts, has also struggled and is expected to phase out its MOx program by 2019. Instead, it has announced plans to start building in 2020 a new kind of fast-breeder reactor, known as ASTRID. This reactor is designed to generate energy by converting high-level nuclear waste into less dangerous residues, which require storage for several hundred years rather than many thousands of years, as is the case with plutonium. But this project has been delayed until at least 2030.

By far the best way to handle plutonium is to store it in secure long-term repositories underground. Having long banked on conversion, neither France nor Britain has permanent facilities; they keep plutonium in interim storage at reprocessing plants. Only two states have begun building viable long-term storage. Finland is constructing a vast facility blasted out of granite, which should be usable as of 2020. In the United States, underground chambers that can accommodate 12 metric tons of plutonium have been dug in New Mexico.

Considering Japan’s many vulnerabilities, particularly seismic activity, nuclear waste should no longer be stored there. The Japanese government should pay its closest allies to take its plutonium away, permanently.

Britain already holds about 20 tons of Japan’s plutonium, and France, about 16 tons, under contracts to reprocess it into usable fuel. Under current arrangements, this fuel, plus all byproducts (including plutonium), are to be sent back to Japan by 2020. Instead, Japan should pay, and generously, for that plutonium to stay where it is, in secure interim storage. And it should help fund the construction of secure permanent storage in Britain and France.

The Japanese government should also pay the United States to take the nearly 11 tons of plutonium currently in Japan. This proposal will seem controversial to some Americans, but the two states already have arrangements for the exchange of nuclear material. (With Finland, however, the proposition is a political nonstarter.) But it will take many years to build additional permanent storage in the United States -- and overcome likely opposition in Congress -- so in the meantime, Japan’s plutonium should be stored in interim facilities at American plants.

Handling Japan’s plutonium would be a great burden for receiver countries, and Japan should pay heftily for the service. But even then the expense would likely amount to a fraction of what Japan spends on its ineffectual plutonium-energy infrastructure: By the most conservative estimate, the Rokkasho facility is expected to cost $120 billion over its 40-year lifetime.

The benefits of this policy would extend far beyond Japan. An earthquake near Rokkasho could trigger an unprecedented nuclear catastrophe; preventing such an accident is in the whole world’s interest. And by funding the construction of long-term storage facilities overseas, Japan wouldn’t just be solving its plutonium problem. It would also be helping other states mitigate their own.

Peter Wynn Kirby is a nuclear and environmental specialist at the University of Oxford.