April 6, 2010

Citizens' Nuclear Information Center* is deeply concerned about the grave risks involved with the restart of the Monju Prototype Fast Breeder Reactor (FBR).¹ Safety, economic and nuclear proliferation issues are being ignored for purely bureaucratic reasons.

Safety Issues
Monju has been shut down since a sodium leak and fire in December 1995. Over the ensuing fourteen years equipment and piping has aged. Modifications have been carried out, but the fundamental safety problems remain. The restart of Monju entails the inherent dangers of a run away chain reaction and a serious accident caused by leakage of the molten sodium coolant.

Even after safety checks were supposed to have been completed, there were repeated false alarms from Monju's sodium leak detectors. This is one of the reasons why restart has been delayed by over two years. The false alarms and the delay in reporting them highlighted the organizational problems of Monju's owner-operator, the Japan Atomic Energy Agency (JAEA). In particular, the false alarms revealed deficiencies in JAEA's quality control system. JAEA's inability to sort out these problems proves that the measures taken since the plant was shut down were desktop exercises that failed to resolve the underlying problems with JAEA's organizational culture.

JAEA says there are no problems with Monju's equipment. However, the inspections were insufficient to justify this claim. Visual inspections were carried out on only a small fraction of the inside of Monju's extensive piping. Furthermore, only one fuel assembly was inspected and even then only external visual inspections were conducted to confirm that there were no penetrating holes. Individual fuel pins were not checked.

Serious questions also remain regarding seismic safety. As a result of changes to the seismic safety assessment system, two active faults below the Monju site that were previously denied have now been recognized. In response, JAEA raised the predicted "design basis earthquake ground motion".² However, Monju was built 20 years ago to meet a design basis that was set 30 years ago. JAEA says the revised assessment is based on the real strength of the buildings and equipment, but the fact is that the safety margin has been reduced.³

Doubts also remain about the size of the revised design basis earthquake ground motion. In particular, uncertainties relating to (a) the fault plane, (b) the rate at which seismic energy is diffused, and (c) the vertical ground movement suggest that JAEA's estimate is too low.⁴

We are concerned both about Monju's equipment and about the culture and attitude of JAEA, the organization that operates Monju. We believe that Monju is an accident waiting to happen and that it is, therefore, irresponsible to restart the plant.

Economic Issues and the Futility of Japan's FBR Program
Even more fundamental questions arise in relation to the role of Monju. It no longer has any value as a prototype. Fundamental changes will be made in the proposed demonstration FBR to follow Monju. It is said that two demonstration FBRs will be built. What this really means is that the first demonstration FBR is being seen as a prototype. Under these circumstances, using Monju to generate electricity for 10 years is irrelevant. Restarting Monju is just a bureaucratic exercise.

Indeed, it is doubtful whether fast breeder reactors will ever be commercialized. The Japanese Government aims for commercialization from 2050. That is 80 years behind the original target of 1970, set back in 1956 in Japan's first nuclear power plan. The fact is that the 2050 target date has no basis in reality. The leading countries in FBR development have all withdrawn, because they were unable to overcome technical and economic hurdles and a lack of social acceptance. Considering the attrition of technical skills and JAEA's past record, it is hard to believe that Japan will succeed where other countries could not.

In order to become commercially viable, FBRs must become at least as economic as light water reactors. However, based on the construction costs of Monju, scaling up to commercial size would result in costs several times greater than light water reactors. Furthermore, continuing along the current technological trajectory is unlikely to produce the hoped for economies of scale.

It is profligate in the extreme to keep pouring money into the development of fast breeder reactors. The only outcome of the bureaucracy-driven fixation with this program will be technological stagnation. Other promising technologies, such as sustainable energy, will be held back as a result of distorted research and investment priorities.

Nuclear Proliferation
It is a great irony that Monju is being restarted when unprecedented international attention is being given to nuclear security. The plutonium that will be "bred" in Japan's FBRs is "super weapons grade" material, which will be relatively easy to separate.⁵ Japan is likely to find it increasingly difficult to gain international acceptance for its fast breeder program. As it is, Japan is setting a very bad example for other countries. Japan's FBR program complicates efforts to control the spread of weapons-usable materials and potential proliferators use Japan as an alibi to justify their own programs.

Protests and Demands

• We protest the restart of Monju.
• We demand that the government stop playing Russian roulette with our lives and permanently close down Monju.
• We demand that Japan withdraw from fast breeder reactor development completely.

Hideyuki Ban
Co-Director
Citizens' Nuclear Information Center (CNIC)

* Founded in 1975, Citizens' Nuclear Information Center is a Tokyo-based non-profit NGO dedicated to securing a safe, nuclear-free world.

Notes
1. Monju is located in Tsuruga City, Fukui Prefecture. Click here for background information about Monju and Japan's FBR program.
2. New seismic design guidelines were introduced in September 2006. Monju's design basis earthquake ground motion (S2 under the Old Guidelines and Ss under the New Guidelines) was subsequently increased from 466 Gal to 760 Gal. (1 gal = 0.01 m/s².)
3. JAEA claims that the safety of fuel assemblies and some equipment and piping will be confirmed based on consideration of time history waveforms. However, there is no empirical seismic data for the Monju site on which to base calculations of time history waveforms.
4. (a) The upper extremity of the fault plane should be set at a depth of 3km rather than 4km. (b) The damping factor of the ground above the fault plane down to a depth of 630m should be set at 1% rather than 3%. (c) The vertical ground movement has been set at two thirds the horizontal movement. However, considering that there are active faults directly beneath the plant, a larger vertical ground movement should be assumed.
5. When FBRs are used in "breeder" mode, plutonium is produced in a blanket of depleted uranium around the core. The plutonium produced in the blanket has a concentration of 98% plutonium-239, the most convenient plutonium isotope for nuclear weapons production. It is relatively easy to separate this plutonium, because the depleted uranium blanket is less contaminated with highly radioactive fission products than regular spent fuel.

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