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Full MOX Reactor to Burn Japan's Growing Plutonium Stockpile

On April 23 the Minister of Economy Trade and Industry approved the establishment of the Ohma nuclear power plant (NPP) in Ohma Town, Aomori Prefecture. This article is adapted from the first of a series of articles about the planned Ohma NPP published in CNIC's Japanese newsletter.

Part of the site not yet acquired
Ohma Town is located on the northern-most tip of Honshu, Japan's largest island (see map on page 5). A major problem for the Ohma NPP is the fact that a parcel of land right in the middle of the site has not yet been acquired. The area of this piece of land is a little over 1% of the 1.32 million square meter site and it includes the location originally proposed for the reactor building. It belonged to the late Asako Kumagai, who refused to sell it on the grounds that "the environment of Ohma cannot be exchanged for money". Her heirs have chosen to honor her wishes.

The owner and operator of the Ohma NPP, Electric Power Development Co. Ltd. (J-Power), was converted from a special semi-government company to a joint-stock company listed on the Tokyo Stock Exchange in October 2004. J-Power submitted an application for permission to establish the Ohma NPP in 1999. At that stage, including Asako Kumagai's parcel of land, it still hadn't acquired about 2% of the site. Nevertheless, the government accepted this unreasonable application.

With its land acquisition plan stalled, in October 2001 J-Power submitted a request to the Ministry of Economy Trade and Industry (METI) for a temporary suspension of the safety review. Then in February 2003, faced with privatization and having given up hope of Asako Kumagai parting with her land, J-Power announced a change of plan in which the location of the reactor core was shifted 200 meters to the south. As a result, Kumagai's land is now 300 meters from where the core of the reactor will be located.

In March 2004 J-Power withdrew its original application and submitted a new one in its place. This is the application which the minister approved in April this year, after the safety review reached the conclusion that the radiation exposure at the borders of the site will not be a problem. Given the location of the Kumagai parcel, like an island that is legally outside the site, this is a highly dubious conclusion.

New Earthquake Guidelines
In September 2006, after the Nuclear Industrial and Safety Agency (NISA) had completed its safety review and the application had been referred to the Nuclear Safety Commission (NSC), a new version of the Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor Facilities (New Earthquake Guidelines) was promulgated (NIT 112, 123). Flowing from the New Earthquake Guidelines, changes were made to the Ohma NPP application. The changes related to such things as the evaluation of active faults, the design basis earthquake ground motion and the classification of equipment in terms of importance in seismic design. As a result of these changes, Ohma will be the first NPP to be assessed under the New Earthquake Guidelines.

The possibility that an active fault runs directly beneath the Kashiwazaki-Kariwa NPP was highlighted by the Chuetsu-oki earthquake, which struck the plant in 16 July 2007. That earthquake revealed the problems with the method used hitherto to identify active faults. The Chuetsu-oki earthquake was a far stronger earthquake than was assumed in the safety review of the Kashiwazaki-Kariwa NPP. It damaged the site, buildings and equipment of the plant, and even now, although almost a year has passed, only a fraction of the inspections have been completed. As the full picture emerges, it is possible that the New Earthquake Guidelines and the current safety review method will be called into question.

Coming at such a time, it can only be concluded that the approval for the Ohma NPP was an attempt to forcibly close the safety review.

Trump Card for Consuming Japan's Plutonium?
Ohma will be a 1,383 MW "Advanced Boiling Water Reactor" (ABWR). It is planned that the reactor will be fully loaded with mixed plutonium-uranium oxide (MOX) fuel. In the so-called "pluthermal" system to be used in Japan's other reactors, the reactor core will take a maximum one-third load of MOX fuel. People are concerned about the safety implications of raising the MOX load to 100% for Ohma.
Why is such a dangerous reactor necessary? The complicated history of the Ohma plan tells the tale. Originally a CANDU reactor was planned for Ohma. Later this was changed to an Advanced Thermal Reactor (ATR), but the Federation of Electric Power Companies (FEPCO) demanded that the government abandon the ATR plan and use a full-MOX ABWR instead. To fit in with Japan's plutonium use plan, the Ohma reactor was changed repeatedly until finally a world-first full-MOX design was chosen.

J-Power now owns no nuclear reactors and no plutonium. All the plutonium required for Ohma's MOX fuel will be transferred from other electric power companies. These companies hope that by burning their plutonium Ohma will make up for the problems they are experiencing with their own pluthermal programs. Tokyo Electric Power Company, in particular, has no immediate prospect of moving forward with its pluthermal program.

Reactor with Conditions Attached
On completion of Ohma's safety review, the head of the Nuclear Safety Commission, Atsuyuki Suzuki, gloated, "This is the first case in Japan in a long time of a plan for a nuclear power reactor at a new site." However, he also attached many unusual conditions saying, "The foundation of the safety confirmation of this plan is the results of the basic design stage safety review, but it goes without saying that this is the starting point. There are also many issues that depend on future efforts."

The approval includes a document entitled "Confirmation after the detailed design stage of the Ohma Nuclear Power Plant". This document requires detailed reports to confirm the earthquake resistance margins of buildings, equipment and pipes that are important for the plant's safety in the event of an earthquake. Also, although it is planned that the Ohma NPP will eventually operate with a full-MOX core, it will not begin with a 100% MOX load. Since it will be the first full-MOX reactor in the world, core data must be reported and checked at each stage as the percentage of MOX fuel is gradually increased.

Ohma will be a new type of reactor with an unprecedented full-MOX core. It will be operated by a company that has no previous experience of operating a nuclear reactor on the basis of an unconvincing safety review. The attitude seems to be "Build it and give it a go. Treat it as a full-MOX experiment."

By Masako Sawai (CNIC)

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