Following the occurrence of Niigata-Chuetsu-Oki Earthquake on July 16,
2007, The Tokyo Electric Power Company, Incorporated (TEPCO) has decided
to conduct a geological survey employing maritime sonic prospecting in a
water area adjoining the Kashiwazaki-Kariwa Nuclear Power Station (NPS)
encompassing the aftershock region in a bid to reflect information
obtained from the said earthquake properly to the seismic safety assessment
of the Kashiwazaki-Kariwa NPS. (Announced on July 26, 2007)
As a result of a subsequent in-depth preparatory study, we have decided
to expand the scope of a geological survey for seismic safety assessment
promoted since last year in a land area adjoining the NPS to include
subsurface exploration etc. in addition to the maritime sonic prospecting.
The contemplated survey will cover an extensive land area encompassing the
Nagaoka Plain Western Rim Fault Zone in addition to the immediate land
area adjoining the NPS and active faults in the area will be checked and
evaluated again by evaluating underground geological structures with
subsurface exploration etc.
Boring and other surveys will also be performed on the station premises
to check and evaluate deep geologic structures beneath the NPS site as
well as to check soil characteristics after the earthquake with collected
samples to evaluate land subsidence and soil liquefaction risks.
At the Fukushima Daiichi and Daini Nuclear Power Stations, we will also
conduct geological surveys in water and land areas adjoining the NPS to
supplement the past geological surveys and enhance our knowledge, taking
into account the recent earthquake experience. The plan calls for the
execution of subsurface exploration in a land area adjoining the NPS, a
maritime sonic prospecting in an adjoining water area and boring surveys
on the station premises and we will set about these surveys as soon as
preparatory arrangements are finished.
(Appendices)
Geological surveys planned at Kashiwazaki-Kariwa NPS following
Niigata-Chuetsu-Oki Earthquake(PDF 421KB)
Geological surveys planned at Fukushima Daiichi / Daini NPS following
Niigata-Chuetsu-Oki Earthquake(PDF 412KB)
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