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Comment by maxerickson | Hacker News Reader

This report directly disagrees with Further, at the time of its commissioning, the tsunami it experienced was accepted by the best engineering data at the time to be impossible. Directly.

This part uses scare quotes to describe the 'quality' of the work:

Its initial application was based on the 3.122 m measurement local tsunami height (above Onahama Peil (O.P.) reference sea level), observed during the 1960 Great Chilean tsunami at or close to Fukushima [32]. The flooding estimate was provided to the nearest millimetre, underscoring a false sense of accuracy in the safety assessment that is impossible even today. With hindsight, it also underscores the ‘quality’ of the engineering work and of its review.

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British use of quotes is typically distinguished from American, in that where emphasis using language from the original document is intended, those words are typically quoted. You'll see this extensively in BBC headlines.

They're not "scare quotes", to quote you. They're direct quotations, for emphasis.

I've definitely noticed that. I often misread BBC headlines as scare-quotes at first, which is sometimes funny. Two on there right now: Ministers 'in listening mode' on tax credits; 'Autonomy' plan for Scottish Labour.

Those quote marks are in the report to indicate sarcasm.

Useage elsewhere doesn't support your comment. E.g., in the introduction:

Interestingly, while the Onagawa NPP was also hit by a tsunami of approximately the same height as Dai-ichi, it survived the event ‘remarkably undamaged’.

I believe I misquoted the IAEA, but I did find the actual report [1] which talked about the Tsunami hazard. As reported it was "Fukishima's tsnumani vulnerability has been regularly updated with the latest accepted methodology." (and I relayed that as meeting the standards of the time) but the actual report also concludes that the methodology was insufficient because it did not consider beyond the most recent few hundred years.

But perhaps more importantly this is a great example of how complex these things can be. The "accepted methodology" and by that they mean the one the regulators hold them to, failed to consider a more geologically relevant time span (thousands of years versus hundreds of years).

My understanding of the situation was that the regulators said "Tell us you have accounted for tsunamis" and TEPCO said "We have, using the accepted methodology, here are the results."

So when did we know the methodology was wrong or insufficient? A lot of people had access to what TEPCO filed and their rationale over the 40+ years of operation. I'm interested if there was a concerted effort, pre-disaster, to get the methodology changed.

[1] "While the tsunami hazard assessment ha d been periodically updated at the Fukushima nuclear power plant taking into account the latest accepted methodology in Japan, the magnitude of the tsunami hazard was underestimated because it was based solely on historical data on relatively recent events (occurring within the past few hundred years). " -- https://www.iaea.org/sites/default/files/protection040912.pd...

The article talks about the Soloviev & Go catalogue how it wasn't taken into account: "Presumably on the basis of these studies, [Soloviev & Go] assigned it a tsunami intensity I=4, which is one of their highest values for Japan tsunamis. Yet, in the aftermath of the Fukushima accident, it has been argued repeatedly that the Jōgan tsunami had not been documented until 2001 [17], well after the design of the NPP"

Also, the 2007 journal paper that found insufficient protections at Fukushima: "The senior author of [46] was then a TEPCO scientist, while another two co-authors are two of the most senior tsunami engineers in Japan. We wonder how disappointed they must have been on 26 November 2010, when, in the symposium organized by JNES, they found out that TEPCO did not appear to have heeded their recommendations [46] in its re-assessment of Fukushima Dai-ichi"

I haven't read the whole report, these are just 2 that I picked up.

The article cites the safety culture at the company that runs the compared reactor and discusses how they went about deciding what sort of events they needed to plan for. They apparently knew what they were doing in 1968 and did not lean on passing the regulatory minimum (the reports cites later studies of how the plant is situated and the relative lack of damage from the 2011 tsunami).

> the tsunami it experienced was accepted by the best engineering data at the time to be impossible.

I find that hard to believe. It was the 4th largest earthquake in the last century and doesn't make the Wikipedia list of "Megatsunamis". It was more a question of how long between such extreme events than if such an extreme event could occur.

Megatsunamis are caused by large volumetric displacements of water resulting from massive amounts of earth entering the water. The tsunami that caused the Fukushima disaster was not a megatsunami - it was caused by thrust faulting resulting in underwater displacement rather than the megatsunami mechanism discussed above.

The analogy here is splashing your hand into water (megatsunami) versus moving your hand underwater.

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