The agreement reached last week by nations at the Nuclear Security Summit to minimize their stockpiles of plutonium gives more reason for Japan to review its nuclear fuel cycle program, under which it plans to reprocess spent fuel from nuclear power reactors to extract plutonium for reuse — despite uncertainties over how its already large stock of separated plutonium would be consumed.

In a bid to reduce the amount of nuclear materials that can be exploited for terrorism purposes, world leaders gathering at the summit held March 24-25 in The Hague, the Netherlands, agreed in their joint statement that protective measures in storing weapons-grade plutonium and highly enriched uranium should be updated. The communique also urged the states to cut the stockpiles of both nuclear materials to the minimum level "as consistent with national requirements."

Japan is the only non-nuclear weapons country to have a program to reprocess spent nuclear fuel on an industrial scale. To dispel nuclear proliferation fears, the government has pledged that it will not possess plutonium whose use has not been decided.