TABLE 3.3 Tsunami Wave Height Estimates at the Fukushima Daiichi and Fukushima Daini Plants

    Tsunami Height Estimates (meters relative to O.P.a)
Date Estimate Basis Fukushima Daiichi Fukushima Daini
1966-1980 (plant permits) May 22, 1960 earthquake near Valdivia, Chile 3.122 (Units 1-6) 3.122 (Unit 1) 3.690 (Unit 2) 3.705 m (Units 3 and 4)
2002 JSCE (2002)b methodology 5.7 5.2
2007 Fukushima Prefecture Disaster Prevention Plan ~5.0 ~5.0
2007 Ibaraki Prefecture Disaster Prevention Plan 4.7 4.7
2008 TEPCO trial calculations using fault models for HERP postulated earthquake 8.4-10.2 (Inundation heights: 13.7-15.7) 7.6-8.2 (Inundation height: 15.5)
2008 TEPCO trial calculations for Satake et al. (2008) model for Jogan tsunami 8.7-9.2 7.8-8.0
2009 JSCE (2002) with updated tidal and bathymetric data 6.1 5.2

a Onahama Port Construction Standard Surface.

bAn English-language version of this paper was issued in 2006. SOURCES: TEPCO (2012b); TEPCO presentation to the committee, September 6, 2012.

methodology to estimate maximum tsunami wave heights at their plant sites. Based on this new methodology, the maximum tsunami wave height at Fukushima Daiichi was estimated to be O.P. + 5.7 m, over 2.5 m higher than the estimate in the plant’s original permit. The maximum tsunami wave height at Fukushima Daini was estimated to be O.P. + 5.2 m, over 2 m higher than the estimate in the plant’s original permit (Table 3.3).

TEPCO took several countermeasures to protect critical equipment and infrastructure at its plants in response to these new estimates. At Fukushima Daiichi, TEPCO raised the elevations of seawater pumps used to cool



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