Fukushima Daiichi Meltdowns Were Stoppable – TEPCO


Tokyo Electric Power Co. (TEPCO), the utility company behind the failed Fukushima Daiichi Nuclear Power Plant in Japan, has admitted that the triple meltdown at the site could have been avoided had the firm been more vigilant and ready.

The mea culpa comes after TEPCO had in the past said that it handled the crisis as best as it could and that its facility located in the Futuba District of the Fukushima Prefecture in Japan was prepared for a disaster such as the earthquake and tsunami which hit Japan in March 2011.

In a report that summarizes the groundwork the company will be taking to improve its policies, TEPCO revealed what decisions the company took and their effects which ultimately led to the triple meltdown at the Fukushima Daiichi plant.

In summary, TEPCO said that it had failed to better prepare for the tsunami which hit the plant because of fear of political, economic and legal repercussions of making improvements to the plant.

“Based upon a profound remorse for the Fukushima nuclear accident, pride and overconfidence in the traditional safety culture and measures has been discarded and we are resolved to reform of management culture,” TEPCO said.

“Our mandate as the operators that caused this tragic accident is to communicate to the world the lessons learned at Fukushima,” the firm began its report.

The company vows that it will work its hardest to prepare in order for no similar catastrophic incident to happen in the future.

TEPCO also vowed to learn from Fukushima and prepare its Kashiwazaki-Kariwa Nuclear Power Plant accordingly.

TEPCO, Fukushima Daiichi, nuclear, meltdown, investigation, Tsunami, Japan,

In a striking admission of its mistake, TEPCO wrote in the report that “When looking back on the accident, the problem was that preparations were not made in advance, so we need a ‘Reform Plan’ that will allow us to be sensitive in capturing opportunities for improvement and safety enhancement and lead to actual measures.”

Furthermore, TEPCO said that “It was possible to take action with the principle of defense-in-depth.”

Defense-in-depth, the firm defines, is assuming that abnormalities will occur to implement measures against abnormalities. The principle also provides for the implementing body to assume abnormalities will expand or that there will be greater abnormalities.

This approach is used in this manner by repeatedly rejecting previous assumptions to ensure a high level of reliability and certainty in ensuring safety when implementing safety measures.

According to TEPCO, “It was possible to diversify safety systems by referencing severe accident measures taken in other countries” and that “Instead of training just as a formality, an organization with practical capability to manage accidents should have been designed and trained with allocation of materials/equipment.”

TEPCO also outlined in a very detailed manner, in sections of its report titled “Looking Back on Previous Tsunami Assessment”, where it could have done better.

The utility firm wrote:

  • There was over-reliance on the JSCE assessment methodology.
    • Management: Emphasized JSCE assessment (authority) to implement practical measures.
    • Tsunami assessor: Historical high was thought to be the 1960 Chile Tsunami (3.1m) and that the assessed value of 5.7m had double the conservatism. There was no awareness that a tsunami exceeding site elevation would directly result in a severe accident.
    • Equipment manager: Took the results from the tsunami assessor as the design conditions and did not verify the conservatism of the assessment method independently.
    • Safety manager: Defense-in-depth was not fully applied to external events.
    • Risk Management Committee: Only discussed tsunamis as a licensing risk.


  • Determined that a massive tsunami would not hit because there were no watermarks or records of one.
    • There are only few centuries of tsunami records and about 1,000 years for geological analysis. It was a not possible to predict the scale of a tsunami with only such records.
    • Immature probabilistic methods, such as supplementing shortage of observation data with expert questionnaire survey, led to under-assessment of tsunami occurrence frequency.


  • Knowledge from other countries was not promptly incorporated into NPS measures.
    • Information of the 1999 Le Blayais NPS off-site power loss event (caused by flooding) was not used to implement countermeasures.


  • After completing severe accident measures in 2002 including containment venting and power supply cross-ties between units, no further measures for severe accidents were taken.


  • There were concerns of back-fitting operating reactors and litigation depending on the recent intention of the Nuclear Safety Commission to regulate severe accident measures.


  • There was concern that if new severe accident measures were implemented, it could spread concern in the siting community that there is a problem with the safety of current plants.


  • In terms of US anti-terrorism measures (B5b), though there was no official information provided, there was a lack of attitude to independently assume terrorist attacks since 9.11 and lack of sensitivity to US NPS site visit information.


  • Unable to share information on status of important equipment which did not lead to prompt and adequate action. On the other hand, various information regardless of its importance was brought to the table, hindering prompt/adequate decision-making.


  • Lack of engineers that were experts in system design, operation and lay-out.


  • Inability to conduct in-house work such as connecting temporary batteries and compressors promptly and smoothly.


  • On-site workers were exhausted due to response to extended accident of multiple units.


  • Confusion in response actions due to orders from headquarters and the Prime Minister’s Office.


  • On top of shortage of materials/equipment, there was no prompt resupply.


Of particular interest here is that TEPCO was fearful of getting sued, did not enhance the site’s measures against catastrophes after it implemented measures in 2002, was afraid that improvements would cause alarm to the community about the site’s safety, had confused workers in the aftermath of the event, had few engineers experienced in system design, and had a shortage of equipment.

For the full TEPCO report that’s riddled with information, click the source link below.

TEPCO, Fukushima Daiichi, nuclear, meltdown, investigation, Tsunami, Japan,

Sources: TEPCO Report; The Asahi Shimbun

Images from CHUCKage & matthileo on Flickr (CC)

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Author: Solon Harmony Dolor

A passion for technology and journalism makes this upcoming writer very interested in social media and technology news. Fresh from finishing an English and Journalism degree from the University of the Philippines Diliman, he aims to bring interesting news to our readers . Don't forget to subscribe and receive our latest posts in your inbox.

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