By Shaun Burnie with Mycle Schneider

China has urged Japan to return over 300 kilograms of weapons grade plutonium to the Unites States and to explain how it intends to resolve its surplus plutonium problem. At a regular press briefing in Beijing on 17 February 2014, and in response to a question on Japan's plutonium stocks, a Foreign Ministry spokeswoman stated:

"China attaches great importance to nuclear proliferation risks and potential threats posed by nuclear materials to regional security. China has grave concerns over Japan's possession of weapons-grade nuclear materials... Japan's failure to hand back its stored weapons-grade nuclear materials to the relevant country has ignited concerns of the international community including China."

As reported in January 2014, agreement has been reached between the United States and Japan for the return of plutonium used in the Fast Critical Assembly (FCA) in JAERI Tokai Research Establishment, Tokai-mura, Ibaraki Prefecture. The formal agreement is expected to be concluded at the Nuclear Security Summit in the Netherlands in March 2014. In its latest declaration to the International Atomic Energy Agency (IAEA) and in its 2012 plutonium management report Japan stated that the FCA facility has the total of 331 kg of plutonium, of which 293 kg is fissile plutonium. The largest share of this plutonium was supplied by the United Kingdom in addition to that supplied by the United States.

Commenting further, the Chinese Foreign Ministry declared:

"China believes that Japan, as a party to the Treaty on the Non-Proliferation of Nuclear Weapons, should strictly observe its international obligations of nuclear non-proliferation and nuclear security. The IAEA requires all parties to maintain a best possible balance of supply and demand of nuclear materials as contained in the Guidelines for the Management of Plutonium. Japan's large stockpile of nuclear materials including weapons-grade materials on its territory is an issue concerning nuclear material security, proliferation risks and big supply-demand imbalance."

In addition to the call for the return of the weapon's grade plutonium, the Chinese statement also raises a question over Japanese fuel cycle policy and its inability to use its existing plutonium stocks. With all 48 nuclear power reactors shutdown there is currently no demand for its separated plutonium as mixed oxide (MOX) fuel. However, Japanese policy continues to plan the commercial operation of the Rokkasho-mura reprocessing plant as early as October 2014, following a safety assessment by the Nuclear Regulatory Authority (NRA). In its latest declaration to the IAEA, Japan's Atomic Energy Commission reported that as of 31 December 2012, Japan held 44,241 kg of separated unirradiated plutonium, of which 9,295 kg was stored in Japan and 34,946 kg was stored abroad. Japan's plutonium program, its challenges and alternatives was recently addressed at a Tokyo symposium and in detailed analysis by IPFM.

As yet, there has been no official response from the Japanese government to the Chinese Foreign Ministry statement, which has been extensively reported through Chinese media outlets.