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| Titel |
Fukushima nuclear power plant accident was preventable |
| VerfasserIn |
Utku Kanoğlu, Costas Synolakis |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108930
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| Publikation (Nr.) |
 EGU/EGU2015-8773.pdf |
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| Zusammenfassung |
| On 11 March 2011, the fourth largest earthquake in recorded history triggered a large
tsunami, which will probably be remembered from the dramatic live pictures in a country,
which is possibly the most tsunami-prepared in the world. The earthquake and tsunami
caused a major nuclear power plant (NPP) accident at the Fukushima Dai-ichi,
owned by Tokyo Electric Power Company (TEPCO). The accident was likely more
severe than the 1979 Three Mile Island and less severe than the Chernobyl 1986
accidents. Yet, after the 26 December 2004 Indian Ocean tsunami had hit the Madras
Atomic Power Station there had been renewed interest in the resilience of NPPs to
tsunamis.
The 11 March 2011 tsunami hit the Onagawa, Fukushima Dai-ichi, Fukushima Dai-ni,
and Tokai Dai-ni NPPs, all located approximately in a 230km stretch along the east coast of
Honshu. The Onagawa NPP was the closest to the source and was hit by an approximately
height of 13m tsunami, of the same height as the one that hit the Fukushima Dai-ichi. Even
though the Onagawa site also subsided by 1m, the tsunami did not reach to the main critical
facilities. As the International Atomic Energy Agency put it, the Onagawa NPP survived
the event "remarkably undamaged." At Fukushima Dai-ichi, the three reactors in
operation were shut down due to strong ground shaking. The earthquake damaged
all offsite electric transmission facilities. Emergency diesel generators (EDGs)
provided back up power and started cooling down the reactors. However, the tsunami
flooded the facilities damaging 12 of its 13 EDGs and caused a blackout. Among the
consequences were hydrogen explosions that released radioactive material in the
environment.
It is unfortunately clear that TEPCO and Japan’s principal regulator Nuclear and
Industrial Safety Agency (NISA) had failed in providing a professional hazard analysis for
the plant, even though their last assessment had taken place only months before the accident.
The main reasons are the following. One, insufficient attention was paid to evidence of
large tsunamis inundating the region, i.e., AD 869 Jogan and 1677 Empo Boso-oki
tsunamis, and the 1896 Sanriku tsunami maximum height in eastern Japan whose
maximum runup was 38m. Two, the design safety conditions were different in
Onagawa, Fukushima and Tokai NPPs. It is inconceivable to have had different
earthquake scenarios for the NPPs at such close distance from each other. Three,
studying the sub-standard TEPCO analysis performed only months before the accident
shows that it is not the accuracy of numerical computations or the veracity of the
computational model that doomed the NPP, but the lack of familiarity with the
context of numerical predictions. Inundation projections, even if correct for one
particular scenario, need to always be put in context of similar studies and events
elsewhere. To put it in colloquial terms, following a recipe from a great cookbook
and having great cookware does not always result in great food, if the cook is an
amateur.
The Fukushima accident was preventable. Had the plant’s owner TEPCO and NISA
followed international best practices and standards, they would had predicted the possibility
of the plant being struck by the size of tsunami that materialized in 2011. If the EDGs had
been relocated inland or higher, there would have been no loss of power. A clear chance to
have reduced the impact of the tsunami at Fukushima was lost after the 2010 Chilean
tsunami. Standards are not only needed for evaluating the vulnerability of NPPs
against tsunami attack, but also for evaluating the competence of modelers and
evaluators.
Acknowledgment: This work is partially supported by the project ASTARTE
(Assessment, STrategy And Risk Reduction for Tsunamis in Europe) FP7-ENV2013 6.4-3,
Grant 603839 to the Technical University of Crete and the Middle East Technical
University. |
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