Summary of the results of the investigation regarding tsunami generated by
Tohoku-Chihou-Taiheiyo-Oki Earthquake which arrived in Fukushima Daiichi
Nuclear Power Station and Fukushima Daini Nuclear Power Station are as
follows.
At Fukushima Daiichi Nuclear Power Station, on the ocean-side of the main
building area, inundation with inundation height of approximately
O.P. + 14 to 15 meters (inundation depth approximately 4 to 5 meters)
occurred in most of the area. At Fukushima Daini Nuclear Power Station,
inundation with inundation height of approximately O.P. + 6.5 to 7 meters
occurred in the ocean-side areas, however, only surrounding areas of Unit
1 and 2 buildings and the south side of Unit 3 building was inundated
within the main building area.
Accordingly, we have confirmed that the impact of tsunami was relatively
larger in Fukushima Daiichi Nuclear Power Station than Fukushima Daini
Nuclear Power Station.
We will try to comprehend further details such as inundation height within
the site and the surrounding areas, together with details regarding inflow
of seawater to buildings and impact on the facilities.
The current understanding of inundation height and inundation area of
Fukushima Daiichi Nuclear Power Station and Fukushima Daini Nuclear Power
Station are as follows.
[Inundation height]
<Fukushima Daiichi Nuclear Power Station>
Approximately O.P. + 14 to 15 meters (inundation depth approximately 4 to
5 meters) across the ocean-side of main building area where reactor
buildings and turbine buildings are placed.
<Fukushima Daini Nuclear Power Station>
Approximately O.P. + 6.5 to 7 meters (inundation depth approximately 2.5
to 3 meters) in most of the ocean-side areas where seawater pumps are
placed.
Approximately O.P. + 14 to 15 meters (inundation depth approximately 2 to
3 meters) only on the south side of Unit 1 building within the main
building area where reactor buildings and turbine buildings are placed.
[Inundation area]
<Fukushima Daiichi Nuclear Power Station>
Across the ocean-side areas where seawater pumps are placed.
Most of the main building area where reactor buildings and turbine
buildings are placed.
<Fukushima Daini Nuclear Power Station>
Across the ocean-side areas where seawater pumps are placed.
In the main building area where reactor buildings and turbine buildings
are placed, only surrounding areas of Unit 1 and 2 buildings and south of
Unit 3 building.
(No un-up over the slope from the ocean-side area to the main building
area was found.)
[Glossary]
-Inundation height
Height of vestige such as discolored area and remains left on buildings
and facilities, measured from the base level. (See drawing below.)
-Inundation depth
Height of vestige such as discolored area and remains left on buildings
and facilities, measured from the ground level. (See drawing below.)
-Inundation area
Area inundated with tsunami. (See drawing below.)
-O.P. (Base level of Onahama Port construction)
Base level which is 0.727 meters below T.P. (Tokyo Bay mean sea height).
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Appendix: Result of the investigation on Tsunami at Fukushima Daiichi
Nuclear Power Station (PDF 386KB)
Appendix: Result of the investigation on Tsunami at Fukushima Daini
Nuclear Power Station (PDF 459KB)