Monju status and restart schedule

Monju, which was designed on the basis of the findings from Joyo, achieved initial criticality in 1994. It has a role in confirming the technological base for the design and safety and in accumulating the operational experiences of sodium cooled FBRs leading to commercialization. The operation, however, has been suspended since a sodium leak incident occurred at the secondary cooling circuit in 1995. After comprehensive reviews of the validity of FBR development in Japan, as well as the safety of Monju, the plant modification work to guard against sodium leakage was carried out between 2005 and 2007. Seismic safety for Monju was evaluated on the basis of the experience gained from the Chuetsu-oki earthquake at Niigata in July 2007; the standard seismic strength for Monju was modified from 466 gal to 760 gal, and a new seismic strength is now being confirmed for maintaining seismic safety for facilities and equipment. The administration structure was reinforced to overcome the weakness in management, revealed in the troubles with sodium leak detectors and outdoor ventilation ducts. The regulatory authority approved the significant advancement in July 2009. The soundness of the facilities and equipment was also evaluated, the outdoor ventilation duct was repaired in May 2009, and the entire system function test was completed in August. System startup test preparation and inspection will be completed in January 2010. On the basis of these achieve-ments, restart is expected by the end of March 2010.

After the restart of Monju, the initial goals of demonstrating its reliability as an operational power plant and establishing sodium handling technology will be given priority. Then, Monju will be used to further develop high performance FBRs. It is considered that Monju should be used as a base for international research and development in the field of FBR cycle technology by making the plant available for joint use for conducting performance tests and by contributing facilities. The validity of design methods for FBR plants can be confirmed, and their accuracy can be improved by using actual operational data from Monju.

Improving design margin can contribute to the enhancement of the safety and economic competitiveness of demonstration FBRs and commercialized FBRs.

Monju is expected to be used as a site for the human development of future FBRs through operational and maintenance expriences.

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115 4. INTERNATIONAL COOPERATION

International cooperation plays an important role in the development of FBR cycle technology, as its development actually requires a long term effort and a large number of resources. Japan has been promoting multilateral/bilateral international cooperation, such as the Generation IV International Forum (GIF), the JAEA–CEA–USDOE¹ trilateral collaboration on sodium cooled fast reactor (SFR) demonstration/prototypes, and the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO), etc., in order to establish fast reactor cycle technologies using global standard technologies and to develop them efficiently.

The GIF is a representative, multilateral collaboration framework. Japan has participated in this framework since the initial stage of GIF and is a chair country of the policy group. Japan has actively cooperated on SFR systems as a chair country of the system steering committee.

The JAEA, CEA and USDOE have a shared vision for research and development aimed at the commercialization of SFRs and have contributed to the development of successful demonstration/prototype SFRs.

INPRO is a multilateral collaboration framework of the IAEA. Japan has participated in a joint study to assess an innovative nuclear energy system based on a closed nuclear fuel cycle with fast reactors and has implemented the assessment study on the Japanese FBR cycle concept by using the INPRO assessment method.

On the basis of the above mentioned arrangements, Monju has accepted a number of researchers from the CEA, EDF and the USDOE. They analysed the existing Monju operational data on sodium thermohydraulics [12, 13], core physics [14], fuel handling and in-service inspections.

It is expected that research and development can be more efficient, reducing the risk and burden on resources by sharing basic data and infrastracture through active multilateral/bilateral international cooperation. Japan will promote research and development for the FBR cycle through the utilization of interna-tional cooperation.

5. CONCLUSIONS

The development of the FBR cycle technology in Japan has been promoted as the main concept, which is as follows: combining a sodium cooled FBR using

1 CEA: Commissariat à l’énergie atomique; USDOE: United States Department of Energy.

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oxide fuel and advanced aqueous reprocessing as well as the simplified pelletizing fuel fabrication, adopted with innovative technology. The development will be advanced to a new stage after the restart of Monju. The use of operational data for Monju and operational experience and human development is expected to contribute to the enhancement of the safety and economic competitiveness of the demonstration FBR.

Under the FaCT project now in progress, Japan will promote the design study, and research and development of innovative technologies aimed at deciding on the adoption of innovative technologies by evaluating their applica-bility in 2010 and presenting conceptual designs for commercial and demon-stration facilities by 2015, with a view to starting operations by around 2025 and introducing the commercial FBR cycle system before around 2050.

Furthermore, international collaboration plays an important role in the development of the FBR cycle technology, as its development requires long term efforts and a large number of resources. It is expected that the Monju site will become an international base for research and development in the field of FBR cycle technology.

REFERENCES

[1] THE COUNCIL FOR SCIENCE AND TECHNOLOGY POLICY, The 3^rd Science and Technology Basic Plan (JFY2006-JFY2010).

[2] JAPAN ATOMIC ENERGY COMISSION, Framework for Nuclear Energy Policy (2005).

[3] MINISTRY OF ECONOMY, TRADE AND INDUSTRY, Nuclear Energy National Plan (2006).

[4] NODA, H., INAGAKI, T., “Feasibility Study on Commercialized FBR Cycle Systems in Japan –The Results in the First Phase and Future Plans of the Study–,” Global 2001, No.052, Paris, France (2001).

[5] AIZAWA, K., “R&D for Fast Reactor Fuel Cycle Technologies in JNC,” Global 2001, No.050, Paris, France (2001).

[6] SAGAYAMA, Y., et al., “Overall Plan and Progress Situation of “The Feasibility Study on Commercialized FBR Cycle Systems”,” Global 2003, pp.400-411, New Orleans (2003).

[7] SAGAYAMA, Y., “Feasibility Study on Commercialized Fast Reactor Cycle Systems (1) Current Status of the Phase-II Study,” Global 2005, No.380, Tsukuba, Japan (2005).

[8] KOTAKE, S., et al., “Feasibility Study on Commercialized Fast Reactor Cycle Systems / Current Status of the FBR System Design,” Global 2005, No.435, Tsukuba, Japan (2005).

[9] SATO, K., et al., “Conceptual Design Study and Evaluation of Advanced Reprocessing Plants in the Feasibility Study on Commercialized FBR Cycle Systems in Japan,”

Global 2005, No.502, Tsukuba, Japan (2005).

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117 [10] NAMEKAWA, T., et al., “Conceptual Design Study and Evaluation of Advanced Fuel

Fabrication Systems in the Feasibility Study on Commercialized FBR Fuel Cycle in Japan,” Global 2005, No.424, Tsukuba, Japan (2005).

[11] INAGAKI, T., et al., “Development of the Demonstration Fast Breeder Reactor in Japan,” Global ’97, Yokohama, Japan (1997).

[12] CAPELLE, S.. et al., “Analysis of Natural Convection in the Primary circuit of Monju with Super-COPD”, No.302, Proc. of AESJ Fall Meeting, Kochi (2008).

[13] BERJON, A., et al., “Monju calculations with the French system code CATHARE”, Proc. of 2009 Annual Meeting of AESJ, Tokyo (2009).

[14] KAGEYAMA, T., et al., “A Comparative Study of the MONJU Fast Reactor Physics Tests with the ERANOS and JAEA Code Systems”, Proc. of PHYSOR-2006, ANS Topical Meeting on Reactor Physics, Vancouver, BC, Canada. (2006).

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