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Japan's MOX Program and Nuclear Proliferation

Background Paper Prepared for Press Conference at The Foreign Correspondents' Club of Japan, 15 May 2009

Japan's Failed Nuclear Fuel Cycle Policy
It is important to understand that MOX shipments are part of Japan's failed nuclear fuel cycle policy. Japan's plutonium was supposed to be used in fast breeder reactors, but when it became clear that there would be no progress with the FBR program, the policy was shifted to the so-called "pluthermal" program of burning plutonium in light water reactors. This nuclear fuel is called MOX.

MOX refers to a mixed oxide of plutonium and uranium. Plutonium is first separated from Japan's spent nuclear fuel at reprocessing plants in Japan and Europe. It is then mixed with uranium and fabricated into fuel for light water reactors. It is now over twelve years since the pluthermal program was introduced, but still no MOX fuel has been used.

Japan's Growing Plutonium Stockpile
The government's claim that the plutonium will be consumed in Japan's light water reactors is used to justify operation of the Rokkasho Reprocessing Plant. Each year since 2006, electric power companies have published a "plutonium utilization plan", which pretends to show how long it will take to consume the plutonium separated at Rokkasho.1 However, the plans are essentially meaningless, because there is no indication of by when the plutonium will actually be used up. The reality is that the stockpile of plutonium in Japan will continue to grow as long as the Rokkasho Reprocessing Plant continues to operate.

If this MOX shipment goes smoothly and, unlike previous occasions, the fuel is loaded into reactors, it can be expected that it will be the first of many such shipments. There is around 38 tons of plutonium held in Europe and the Japanese power companies are obliged to take it all back. This will cause the stockpile of plutonium held in Japan to grow even faster, because the plutonium returned from overseas will be used before the plutonium separated at Rokkasho.

Currently there are around 9 tons of plutonium held in Japan. This plutonium stockpile and Japan's nuclear fuel cycle program represent a serious proliferation risk.

How Many Bombs Worth of Plutonium?
The IAEA says that 8 kg of plutonium is enough to make one atomic bomb.2 (Actually you can make a bomb with less than this.) There is already enough plutonium stored in Japan to make over 1,000 atomic bombs. If you include the plutonium held in Europe, Japan has enough plutonium to make over 5,000 atomic bombs.

Is MOX Proliferation Resistant?
Japan says that MOX is proliferation resistant, but the IAEA classifies MOX as a "direct use material", which can be converted to nuclear weapons usable form in the order of one to three weeks.3 The process of separating pure plutonium from MOX is chemically straightforward. Also, un-irradiated MOX (which includes MOX powder produced at reprocessing plants and MOX fuel before it is loaded into reactors) is much less radioactive than spent fuel. Highly radioactive spent nuclear fuel is said to be "self protecting", but MOX is much easier to handle. That is why it is such a serious proliferation risk.

Reactor Grade versus Weapons Grade Plutonium
The government and industry say that Japan's plutonium is "reactor grade plutonium" not "weapons grade plutonium". However, the term "reactor grade plutonium" is just a label. It does not mean that it cannot be used in nuclear weapons. The IAEA takes the view that reactor grade plutonium is direct use nuclear weapons material.4 No one doubts that the plutonium stockpiled by Japan could be used in nuclear weapons and it is dishonest for Japan to suggest otherwise.

Super Weapons Grade Plutonium
Japan's fast breeder program has been a total failure, but the government is still persisting with it. A special feature of FBRs is that they "breed" plutonium in a blanket of uranium placed around the reactor. The composition of plutonium thus produced is sometimes referred to as "super weapons grade" plutonium, because it is the most convenient composition for producing nuclear weapons. People should be concerned that if Japan ever succeeds in breeding plutonium in this way it will accumulate a stockpile of this "super weapons grade" plutonium. While this MOX shipment will not be used in the FBR program, it is part of the same overall nuclear fuel cycle policy.

Japan's Nuclear Intentions
The question is, does Japan intend to produce nuclear weapons? The simple answer would appear to be, "not at the moment". There is no evidence that any post-war Japanese government has had a nuclear weapons program. However, comments by some politicians and military personnel suggest that there is reason to be concerned about the potential for this situation to change at some time in the future. A secret Ministry of Foreign Affairs report produced in 1969 stated, "The policy for the time being is not to have nuclear weapons, but the economic and technical potential to produce nuclear weapons will always be retained and care will be taken not to accept any restrictions on this."5 This position is probably more prevalent within the government and the bureaucracy than most people would imagine.

Setting a Bad Example
Japan's nuclear fuel cycle policy makes it much more difficult to persuade other countries to forgo proliferation-prone nuclear fuel cycle programs. It provides an alibi for potential nuclear proliferators. For example, Iran often points to Japan, saying that its own nuclear program is legal just like Japan's.6 Also, Japan is seen as a "virtual nuclear weapons state". Even if it does not obtain nuclear weapons, its ability to produce them quickly is a factor in the security calculations of other states.7

MOX Security and Terrorism
At a time when the threat of terrorism, including ship hijackings, has reached unprecedented proportions, shipping all this plutonium around the world represents an unacceptable security risk. MOX shipments are a tempting target for terrorist organizations, which openly proclaim their desire to obtain nuclear weapons.

It is hard to see how nuclear weapons can be eliminated in a sustainable way unless reprocessing and plutonium fuel cycles are eliminated. The Japanese government proudly proclaims that it is a leader in the quest for nuclear disarmament, but in fact its stubborn determination to continue with its failed nuclear fuel cycle policy is a major barrier to nuclear disarmament.

Philip White
International Liaison Officer
Citizens' Nuclear Information Center


1. See the following page on CNIC's web site for details of the Plutonium Utilization Plan for FY2009:

2. IAEA Safeguards Glossary, 2001 Edition, p.23.

3. IAEA Safeguards Glossary, 2001 Edition, p.22.

4. IAEA Safeguards Glossary, 2001 Edition, p.33.

5. Japanese Foreign Policy Principles ("Wagakuni no Gaikou Seisaku Taikou"), produced in 1969 by the Foreign Relations Policy Committee ("Gaikou Seisaku Iinkai"). The Foreign Relations Policy Committee was an informal committee established within the Ministry of Foreign Affairs in 1968. Translation by Citizens' Nuclear Information Center.

6. The Iranian Foreign Minister, Manouchehr Mottaki, recently responded along these lines to criticisms by Japan's Foreign Minister Hirofumi Nakasone. (Japan Times, 3 May 2009)
Refer also to the following extract from "The Netherworld of Nonproliferation", by James Traub, New York Times, June 13, 2004.
When I pressed Dr. Seyed Hossein Mousavian, a top official with Iran's Security Council, he said bluntly, ''To stop Iran from a legitimate right of NPT [the Nonproliferation Treaty], which is to enjoy the peaceful technology of nuclear power, is not acceptable to Iran.'' Mousavian spoke -- repeatedly -- of ''the double standard,'' of ''discrimination.'' Why should Iran, he asked, be denied benefits available to Japan?

7. See for example "Japan to Go Nuclear If Unified Korea Is Nuke-Armed", The Korea Times, 03-17-2009 11:03
Japan will likely go nuclear if a unified Korea decides to keep the nuclear arsenal developed by North Korea, setting the stage for a tense military competition between the two Northeast Asian rivals, Yonhap News Agency reported Monday, quoting a U.S. congressional report.
"Any eventual reunification of the Korean Peninsula could further induce Japan to reconsider its nuclear stance," the report by the Congressional Research Service was quoted as saying.

Go to MOX Shipments page

Go to MOX and Pluthermal page

Go to Plutonium and Nuclear Proliferation page


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