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December 18 was the 50th anniversary of Japan’s affiliation with the United Nations. At the ceremony Secretary General Koffi Annan called on Japan to stick to its ban on nuclear weapons. His message seems to have been prompted by the nuclear-arms argument in Japan that has emerged since North Korea’s underground nuclear test in October.

Japan is supposed to be powering its nuclear reactors with the plutonium that it has extracted through the reprocessing of spent nuclear fuel. Obviously, Japan’s plutonium management holds great relevance for worldwide efforts against nuclear-weapons proliferation and terrorism.

Japan is going to begin full-scale operation of a new reprocessing plant at Rokkasho village next August. After the reprocessing, this plant will make MOX (mixed oxide) fuel using plutonium separated from spent nuclear fuel.

Japan’s commitment to plutonium recycling has continued since the introduction of nuclear power to Japan and has been explicitly stated in its Long Term Program since 1956. Under Japan’s nuclear regulatory requirements, before they load fuel into reactors, utilities must submit evidence that the resulting spent fuel will be reprocessed. They have also made commitments to local communities that they will ship spent fuel from reactor sites to reprocessing plants “soon” (while specifying no time period). Therefore there has been no choice for utility companies but to make reprocessing contracts.

Despite the cost disadvantage of reprocessing compared with direct disposal or storage of spent fuel, the latest Framework for Nuclear Energy Policy published in November 2005 by Japan’s Atomic Energy Commission (JAEC) did not change the policy that spent fuel must be reprocessed. The Rokkasho reprocessing plant, which turns spent fuel into plutonium, therefore started active testing on March 31, 2006.

The financial risk to Japan’s nuclear utilities from operating the Rokkasho plant has been significantly reduced by the establishment of a “reprocessing fund” that is, in effect, a tax on all Japan’s electric-power consumers to pay the costs. The risk has not, however, been eliminated entirely. Losses due to accidents or operational problems will probably not be covered by the fund.

Since 1977, seven tons of plutonium was separated from Japan’s spent nuclear fuel. In addition, in the 1970s Japan’s utilities made reprocessing contracts with BNFL (in Britain) and COGEMA (in France), which have resulted in the separation of a total of 41 tons of plutonium from spent fuel, out of which only two tons have been returned to Japan.

Japan’s stockpile of separated plutonium held at home and abroad totaled 43 tons by the end of 2004. Japan’s cumulative consumption of plutonium has been only five tons to date and its future consumption rate is still uncertain. But once the Rokkasho reprocessing plant begins operation, Japan will separate about eight tons of plutonium — enough to make 1,000 nuclear bombs — annually. There is every reason to postpone this reprocessing until Japan has dealt with its backlog of separated plutonium.

Japan’s utilities, however, are under pressure to deal with their accumulating spent fuel. According to government and industry estimates, some nuclear-power plant storage pools will be filled by the end of 2006. This is the main reason given for starting operation of the Rokkasho reprocessing plant. In addition, because the Rokkasho plant, even operating at full capacity, will not be able to keep up with the projected discharges of spent fuel, Japan’s utilities have decided to build an interim away-from-reactor (AFR) spent-fuel storage facility. This facility will be built in Mutsu city, Aomori Prefecture, and is projected to start operation in 2010.

Our analysis shows that with optimum use of available at-reactor and AFR storage capacity, there would be no need for reprocessing until the mid 2020s. There would be sufficient spent fuel-storage capacity till between 2025 and 2028.

But the political obstacles to such a no-reprocessing strategy would be severe. Transfers of spent fuel among nuclear-power-plant sites and the siting of additional AFR storage facilities would be opposed by local authorities. Also, because the Japan Atomic Power Company has the exclusive rights to the pressurized water reactor (PWR) spent-fuel-storage capacity at Mutsu, storage pools owned by other utilities could be filled up by 2014, while the Mutsu PWR storage capacity remained unfilled.

Similarly, some boiling-water-reactor sites at reactor pools would fill up by 2019, since the Mutsu storage capacity of 4,000 tons owned by Tokyo Electric Power Company is not scheduled to be completed by then. And, if the Rokkasho plant does not operate as planned, its spent-fuel-storage capacity will likely be filled by 2020.

Japan’s recovered plutonium is to be recycled as light-water-reactor MOX fuel and in Japan’s fast-breeder-reactor (FBR) research and development program. Due to delays in the MOX and FBR programs, however, Japan has accumulated a large stockpile of separated plutonium. If the Rokkasho plant goes into full scale operation in 2007, Japan’s plutonium stockpile will likely grow from from 43 tons in 2005 to more than 70 tons by 2020. Deferring operation of the Rokkasho plant together with optimal spent-fuel storage — at least until the plutonium stockpile had been worked down to the minimum required level — would minimize international concern about Japan’s plutonium stockpile.

The full-scale operation of Rokkasho should be postponed for about a decade. This would be feasible even under the current spent-fuel-storage management planning, and would give Japan sufficient time to reconsider its plutonium and spent-fuel management.

Japanese politicians who argue for nuclear armament could gain momentum with the plutonium-separation technology. China and South Korea are skeptically watching Japan’s situation.

Last month, the president of the Japan Nuclear Fuel Ltd. stated through the media that MOX fuel is “practically impossible” to divert into a nuclear bomb. This comment is scientifically untrue.

Although Japan speaks of a nonnuclear-weapon policy, its rigid domestic nuclear policy for peaceful use is, ironically, raising the international risk of proliferation. If Japan is against nuclear weapons, the Rokkasho reprocessing plant must not be operated as planned.

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