March 9, 2006
Governor Shingo Mimura
Governor’s Office
1-1-1 Nagashima, Aomori City
Aomori Prefecture 030-8570 Japan
Dear Governor Mimura,
We are writing to you to express our concerns about the complacency that seems to exist in Japan regarding the threat posed by the Rokkasho reprocessing plant to international efforts to limit nuclear proliferation. If you give your approval, this plant in your prefecture may start active testing as early as the end of this month — a test that will ultimately separate over 4 tons of plutonium from spent fuel, enough to make more than 500 Nagasaki-type bombs.
One example of this complacency can be observed in the February 14 letter sent by Ambassador Ryozo Kato to six US Congress members, including Edward Markey of Massachusetts, in response to their letter expressing concerns about the implications for nuclear weapons proliferation of the planned startup of the Rokkasho plant. The Ambassador’s letter states, “In addition, Japan has been taking the unique technical measure of producing a mixed oxide of plutonium and uranium at the Rokkasho plant in order to ensure that a pure plutonium oxide substance will not be available,” implying that somehow this mixed oxide is very different from plutonium oxide and is extremely difficult to turn into bomb materials.
It is true that the US and Japan agreed to introduce this measure for the Tokai reprocessing plant, but the measure does not actually provide significant proliferation resistance relative to plutonium oxide. This is reflected in the safeguards procedures of the International Atomic Energy Agency (IAEA), which are no different for a plant producing mixed-oxide than for a plant producing plutonium oxide.
Regarding this, one of us, Dr. Edwin Lyman, presented a letter for you to Mr. Yoichiro Sakuraba, director of Resources and Energy Department, at a meeting on Feb. 24 saying:
“The Japanese government has said that the RRP will not pose a security threat because it will not produce separated plutonium but instead a 50-50 mixture of plutonium and uranium. However, such a mixture would be directly usable in nuclear weapons. In addition, this mixture is no more radioactive or difficult to handle than separated plutonium. For this reason, the International Atomic Energy Agency considers this material to be as useful as separated plutonium for making nuclear weapons, and as vulnerable as separated plutonium to diversion or theft
Before authorizing the startup of the RRP, you should request that the Japanese Government provide a detailed technical explanation as to why this MOX mixture will be significantly less useful in nuclear weapons than pure plutonium oxide. If it cannot provide a technically sound explanation, you should not allow the RRP to begin operation.”
Mr. Sakuraba said that he had never heard about the IAEA guidance which treats MOX mixtures and Pu oxides in the same way. He was given a copy of the relevant pages of the IAEA Safeguards Glossary (1987 version) in Japanese for your reference. The translation was done under the supervision of former Science and Technology Agency of Japan. (The minor revisions in the current, 2001, version do not affect our conclusion on this issue.)
When asked to explain the government position on the discrepancy of the statement made in the letter to Markey et.al and the IAEA guidance in a meeting with Dr. Lyman held on February 21, Mr. Yasuyoshi Komizo, Director of International Nuclear Energy and Science Department, Ministry of Foreign Affairs declined to do so, saying he was not a technical expert. Mr. Komizo, who has served as special assistant to Dr. ElBaradei, Secretary General of the IAEA, also refused to promise to give a written answer of the Japanese government to Lyman and the Congress members at a later date.
It is quite unfortunate that the Japanese government continues to give this kind of misinformation to you, your staff, and the people of Aomori Prefecture on such an important issue and refuse to give any technical justification for the assertion that the MOX mixture is less of a concern for proliferation than plutonium oxide.
Let us repeat here again: Before authorizing the startup of the RRP, you should request that the Japanese Government provide a detailed technical explanation as to why this MOX mixture will be significantly less useful than pure plutonium oxide for proliferant states or terrorists seeking to acquire nuclear weapons. If it cannot provide a technically sound explanation, you should not allow the RRP to begin operation. Otherwise, your decision to start active testing at the RRP will be based on a highly inaccurate and dangerously incomplete assessment of its proliferation risk.”
One of us, Dr. KANG Jungmin, will be in Aomori Prefecture on March 10-11 and would be happy to meet you and your staff to give you further information on this and other related issues.
Yours sincerely,
Dr. Edwin S. Lyman
Senior Staff Scientist
Union of Concerned Scientists
Dr. Jungmin Kang
Independent Nuclear Policy Analyst
Dr. Frank von Hippel
Professor of Public and International Affairs, Princeton University