JpGU-AGU Joint Meeting 2017

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[JJ] Oral

H (Human Geosciences) » H-CG Complex & General

[H-CG33] [JJ] Design basis ground motion for nuclear power plants: Viewpoints of science and engineering

Sun. May 21, 2017 10:45 AM - 12:15 PM A01 (Tokyo Bay Makuhari Hall)

convener:Daisuke Suetsugu(Department of Deep Earth Structure and Dynamics Research, Japan Agency for Marine-Earth Science and Technology), Manabu Hashimoto(Disaster Prevention Research Institute, Kyoto University), Takeshi Sagiya(Disaster Mitigation Research Center, Nagoya University), Kohta Juraku(Department of Humanities, Social and Health Sciences, School of Science and Technology for Future Life, Tokyo Denki University), Chairperson:Daisuke Suetsugu(Department of Deep Earth Structure and Dynamics Research, Japan Agency for Marine-Earth Science and Technology), Chairperson:Kohta Juraku(Department of Humanities, Social and Health Sciences, School of Science and Technology for Future Life, Tokyo Denki University)

11:10 AM - 11:25 AM

[HCG33-02] Design Basis Ground Motion reduces seismic safety of NPP: Proposal of Earthquake Ground Motion for Defense in Depth

*Katsuhiko Ishibashi1 (1.Emeritus Professor, Kobe University)

Keywords:nuclear power plant, design basis earthquake ground motion, defense in depth, trans-science, earthquake ground motion for defense in depth, local commission of information

DBEGM (Design Basis Earthquake Ground Motion) prescribed in Japan's NRA’s (Nuclear Regulation Authority) New Regulatory Requirements is insufficient to accomplish seismic safety of NPPs (nuclear power plants). This is because, in terms of the IAEA's (International Atomic Energy Agency) concept of Defense in Depth in nuclear safety, DBEGM is used merely for seismic design of NPP facilities in Level 1 (prevention of abnormal operation and failures), Level 2 (control of abnormal operation and detection of failures) and Level 3 (control of accidents within the design basis), not having any responsibility for Level 4 (control of severe plant conditions, including prevention of accident progression and mitigation of the consequences of severe accidents). As an example, in case of Sendai NPP's Units 1 and 2 operated by Kyusyu Electric Power Co., Inc., DBEGM Ss-1 (maximum horizontal acceleration 540 Gal) and Ss-2 (maximum horizontal acceleration 620 Gal) are only short-period and short-duration with small CAV (Cumulative Absolute Velocity), which is considered important in the United States, and probably very insufficient to defend additional emergent facilities and human activities of Level 4 against large ground accelerations, velocities and displacements of short to long periods and long duration times due to, for example, the anticipated M 9-class giant Nankai trough earthquake, which is ignored by Kyushu Electric and NRA. Therefore, I propose to establish a new earthquake ground motion, say, EGMDD (Earthquake Ground Motion for Defense in Depth), which important facilities and infrastructures of NPPs should withstand from Level 1 through Level 4. EGMDD should be formulated by taking into account both large earthquakes just beneath NPPs and great earthquakes distant from plants having annual exceedance probabilities of 10-4 to 10-6, and should have broad-band spectrum from short-period to long-period and long duration times. Formulating a proper EGMDD for a certain NPP is a trans-scientific problem. So, it should be decided through exhaustive discussions in such an organization as CLI (Commission Locale d'Information) in France, in which a nuclear utility concerned, municipalities with and without the plant, inhabitants, earthquake scientists and engineers, plant makers, regulation authority, etc, will participate.