Rokkasho: active tests to begin any day　Nuke Info Tokyo No. 111

Active tests at the Rokkasho reprocessing plant are expected to commence very soon. For the first time, plutonium will be separated from spent fuel at Rokkasho. Of course, Japan has been separating plutonium at the Tokai facility since 1981, but Rokkasho will be Japan’s first industrial-scale reprocessing plant. Indeed it will be the first such plant outside the nuclear weapons states, as defined in the Non-Proliferation Treaty (NPT). India has reprocessing facilities, but it is outside the NPT. Of course, this does not excuse India, but the international legal implications are different for Japan.

History of reprocessing in Japan
Perhaps now is a good time to recap some of the history of reprocessing in Japan. Table 1 shows that reprocessing was part of Japan’s nuclear energy policy from the beginning.

Table 1: History of Japan’s reprocessing policy

President Carter agreed to allow Japan to reprocess spent fuel, despite his concerns about proliferation risks and despite abandoning reprocessing in the US. He did so as a result of intense lobbying by the Japanese. A compromise was reached whereby Japan agreed not to extract plutonium in pure form. Instead, plutonium would be mixed with uranium and extracted as a mixed oxide (MOX) powder. (Note that at this stage in the fuel cycle it has not been fabricated into MOX fuel.) This was said to be more proliferation-resistant than pure plutonium oxide. The reality is, however, that the chemical process of separating plutonium from the mixed oxide is not particularly difficult. The IAEA treats MOX powder as a “direct use” weapons-usable material, so clearly the compromise was a political compromise rather than a scientifically based compromise. This compromise was later accepted by the IAEA, which shows that regardless of the importance of IAEA safeguards on nuclear facilities, the IAEA’s decisions are essentially political rather than scientific. This is an important point to remember in the context of the debate over Iranian uranium enrichment.

Waiting for Aomori government approval
As this article is being written, Aomori Prefecture is debating whether to approve the commencement of active tests. Central government approval has already been given, so it is expected that the tests will start soon after the Governor of Aomori gives his consent. He is expected to give his consent on the basis that the central government has assured him that the plant is safe. A safety agreement will then be signed between Aomori Prefecture, Rokkasho Village and Japan Nuclear Fuel Ltd. (JNFL), which owns the plant.

What is reprocessing?
The majority of spent nuclear fuel is uranium which has not undergone any nuclear reaction. About one percent is plutonium, which is formed when uranium-238 captures a neutron. Another approximately three percent of spent fuel is fission products. Besides plutonium, there are also other heavy elements (collectively called actinides) formed by additional neutron capture and beta release. Altogether, this represents a potent mix millions of times more radioactive than the original fuel. During reprocessing, the spent fuel is dissolved in nitric acid and separated out into three streams, uranium, plutonium and the rest. The latter category is by far the most radioactive and is classified as high-level waste.

What do active tests involve?
The objective of the active tests is to test those functions which couldn’t be checked during previous tests, including the quantity of radioactivity released into the environment, separation of fission products, separation of plutonium from uranium and treatment of liquid and solid wastes. These functions can only be tested using spent fuel.

JNFL plans to reprocess 430 tons of spent fuel, including 210 tons of PWR fuel and 220 tons of BWR fuel. The tests will be broken up into two main stages. The first stage will confirm safety and performance of equipment and facilities. These will be tested to confirm that they perform in accordance with design and that they operate within design parameters. The second stage will test the whole plant by operating it in a manner similar to real operations. The purpose of this is to confirm that the plant will be able to operate safely at its full capacity of 800 tons of spent fuel per year. Low burn-up spent fuel which has been cooled for a long period of time will be reprocessed before higher burn-up spent fuel which has been cooled for a shorter period of time. This is because the former is less radioactive than the latter. Altogether, active tests are scheduled to continue for 17 months.

The highest burn-up that will be tested for spent PWR fuel is 47,000 MWd/tU (cooled for between 6 and 17 years) and for spent BWR fuel is 40,000 MWd/tU. (cooled for between 8 and 20 years). The highest burn-up currently permitted for fuel in Japanese reactors is 55,000 MWd/tU. However, no such fuel will be reprocessed during the tests. In order to assess how much radioactivity will be released into the environment when this high burn-up fuel is reprocessed, JNFL will extrapolate from results obtained for the lower burn-up fuels. For this, calculation codes including ORIGEN will be used. We are skeptical that these calculations will give a reliable indication of the amount of radioactivity that will be released when high burn-up fuel is reprocessed. The projected maximum annual releases of radioactivity are shown in Tables 2 and 3 below. JNFL will use these projections as the basis of its assurance that a yearly dose of 0.022 milli-Sieverts to members of the general public will not be exceeded. We believe JNFL is drawing a long bow to connect these calculations to this maximum annual dose.

Table 2: Radioactivity in Aerial Releases

Table 3: Radioactivity in Liquid Releases

A tale of two presidents
There is a great irony in the fact that Rokkasho will begin separating plutonium so soon after President Bush announced that the US plans to return to reprocessing itself. The U.S. plans to use a different reprocessing method than that used at Rokkasho and other existing reprocessing plants. The reason for this is that the PUREX method used at Rokkasho and elsewhere is recognized to present proliferation risks. Setting aside for a moment the fact that scientists are skeptical of whether the process proposed by George Bush is much safer, to be consistent President Bush should now return to the position originally taken by President Carter and request Japan to refrain from operating the PUREX reprocessing plant at Rokkasho.

Philip White (NIT Editor)