8 ms·

As I understand it, the Fukushima plant was never designed or rated to sustain such a large earthquake or tsunami. If this understanding is correct, we should

by nickff 11y ago

As I understand it, the Fukushima plant was never designed or rated to sustain such a large earthquake or tsunami. If this understanding is correct, we should not have expected it to survive the damage, and the problems were not with the design, but perhaps with the specification (depending on whether you think this should have been foreseen). It seems to be a common thread with all tragedies and disasters that people suffer from hindsight bias, and believe that this specific case should have been foreseen. It is not clear what the cost of building everything to sustain all similar low-probability events would be, and whether doing so would be statistical murder.

maxerickson 11y ago
Here's a key phrase from the abstract that suggests more than hindsight bias is involved in the report: The Fukushima accident was preventable, if international best practices and standards had been followed, if there had been international reviews, and had common sense prevailed in the interpretation of pre-existing geological and hydrodynamic findings. Another one: Three, the hazard analysis to calculate the maximum probable tsunami at Dai-ichi appeared to have had methodological mistakes, which almost nobody experienced in tsunami engineering would have made. So there is sense in which they are pretty strongly pointing at regulatory failure.
- Shivetya 11y ago
  When it was built or after? This plant was built in the early eighties. The article doesn't state if it violated the ideals of then or more recent knowledge.
  - maxerickson 11y ago
    The comparison to Onagawa makes it clear enough that they are talking about when it was built. They wouldn't have had so much more experience in 1968 than when they did the early design work for Fukushima Dai-ichi.
  - samstave 11y ago
    Fukushima was built in 1967... and was based on an even slightly older GE plant design. Or were you talking about the other plant?
- ChuckMcM 11y ago
  I'm not sure if you agree that the findings are unsustainable or not. Two things that the IAEA had established were that 1) Fukishima survived the earthquake as designed, and was in the process of shutting down when the tsunami hit. 2) The tsunami disabled primary and backup power to the cooling systems which was the proximate cause of the failure. Further, at the time of its commissioning, the tsunami it experienced was accepted by the best engineering data at the time to be impossible. You can make the argument that over time as more data became available the regulatory agency should have required additional upgrades to cover the larger tsunami risk. There have been plenty of stories about regulatory capture between TEPCO and the regulators which prevented best practices from being followed. A lot of retrofits had been installed over time and that no doubt contributed to its survival of the earthquake.
  - maxerickson 11y ago
    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.
    - ChuckMcM 11y ago
      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.pdf https://www.iaea.org/sites/default/files/protection040912.pd...
- logicallee 11y ago
  The next nuclear accident that will occur in the world is 100% preventable, and without any hindsight bias I will tell you exactly how... after it occurs. /s (seriously, if you want me to take a claim seriously that accidents are preventable, talk about what we are doing wrong today, not in the past.)
  - makomk 11y ago
    Engineers at TEPCO did tell them what they were doing wrong at Fukushima Daiichi. They were ignored: "In 2008, TEPCO did two sets of calculations, one based on the Headquarters for Earthquake Research Promotion (HERP) fault models which suggested tsunami height estimates of 8.4–10.2 m relative to the reference sea level. Another one based on Satake et al. [47] produced 8.7–9.2 m tsunami height estimates which were also apparently dismissed [32]. TEPCO ignored them, claiming there was ‘no wave source model’ for the former, and it required a tsunami deposit investigation for the latter [32]. In 2009, new estimates using updated bathymetry and tidal data yielded a 6.1 m tsunami height [12,32]. This was not followed-up and was only reported to Japan's Nuclear and Industrial Safety Agency (NISA) on 7 March 2011 [48]. A post-event study [48] asserts that ‘a senior NISA official has confirmed to us that NISA neither ‘commissioned nor reviewed’ numerical studies of tsunami run-up at Fukushima Daiichi’." The reason you only hear about these issues after an accident occurs is not because they could only be predicted in hindsight, but because no-one cared about the predictions until after the accident.
    - logicallee 11y ago
      if our title read "Nuclear power plants are still being run recklessly, and the next Fukushima-like accident is likely 100% preventable today" it would get my attention, and I would read what the claims that we need to be doing are. small statistical disagreements about experts on the other hand, are hard to take as seriously.
      - btilly 11y ago
        The thing is that those are not small statistical disagreements. The maximum tsunami+tide they designed for was 5m. Design parameters said that you should have a wall 2x what you think you need so they built a 10m (about 30 foot) wall. Two independent teams came up with realistic tsunamis near that 10m wall (one over and one under), so they should have changed their wall requirement up substantially. But they argued themselves into believing that 6m was a realistic maximum then did nothing. Their estimates were also out of line with actual tsunamis experienced elsewhere. Tsunamis in recent decades from earthquakes similar to the ones that they knew could hit the area have ranged from 3-30m. Even a 7.0 earthquake managed to create a 12m tsunami in New Guinea. The actual tsunami was 13m. The most telling point is how the response afterwards has shown lessons not learned. For example The United States National Research Council of the National Academies had a 21 person panel conduct 18 months of interviews with a wide variety of technical experts on how the disaster could be prevented here. NOT ONE of the members of the panel or the people interviewed was an expert on tsunamis. The author's of the paper clearly believe that if you're studying the aftermath of a tsunami, you should at least talk to someone who studies tsunamis... If the paper is correct, it is a question of time until somewhere in the world we have another entirely preventable major disaster because local officials underestimate tsunami threats that current knowledge is more than sufficient to predict. Of course enough things can go wrong that the next big disaster won't be that. But that preventable disaster is coming...
PaulHoule 11y ago
If you read closely you see that the accident was so bad because of one simple problem. If a nuclear reactor has a cooling failure, the fuel will eventually heat up and then melt down. To prevent this you have to keep water circulating around the reactor core. It doesn't take a huge amount of energy to do this, but it does take some. If the power goes out at the station and they can't get emergency power, the outcome is very bad. If they had spent maybe $300k or so they could have moved the emergency generators a little bit higher up. With that investment there still would have been serious damage to the plant but only a very limited release of radioactivity because the fuel integrity and the coarse integrity of the plant would have been protected.
- deleted 11y ago
  [deleted]
- nickff 11y ago
  I have read that many times, and it makes some sense. The issue with this line of reasoning is that the move would be a design change which is not required by the specification (as I have read and understood it), which would have been seen as unnecessary waste at the time. A study which I would find more important and useful than the one here would be a cost/benefit analysis of increasing all specifications relating to all (similar) low probability events. In other words, if you had been a designer of the plant looking to spend an extra $500000 to make the plant safer, would you have spent it on moving the generators? How many other contingencies would have been higher priorities than this one (if any)? What would be the total cost/benefit of applying this heightened standard to all new facilities? Would this be statistical murder?
  - PaulHoule 11y ago
    When you consider that a nuclear plant costs billions of USD and that billions of USD of damage has been done, the $500,000 upgrade to the generators is a slam dunk. Also based on recent projections, the probability of a tsunami event of that severity was 80% for the next few decades, so it is a no brainer -- particularly when you consider that the nuclear industry worldwide has been set back 20 or 40 years at least by this incident. The NRC has had modernization plans at U.S. reactors that have spent much more than this. For instance the hydrogen bubble formation in that kind of BWR was well known here and reactors in the U.S. have had features added (dependent on a power source) that would get rid of it.
vesinisa 11y ago
The authors argue that there were very serious and repeated shortcomings in the methodology used to estimate the highest possible flooding caused by a tsunami. The plant was designed for 6-meter tsunami from an M=7.5 earthquake, but what actually hit them was a 13-meter tsunami from an M=9.0 quake. I understood it's international standard practice to consider worst-case events from historical record spanning thousands of years in nuclear plant risk analysis, and it is known that almost as strong earthquakes hit Japan in 1933 (M=8.5) and 869 (M=8.6), for example. A plant by a different company just 100 km north of Dai-ichi was built for a 13-meter tsunami, so there was little consistency in what preparations the tsunami analysis actually induced, and the regulator seems to have been indifferent to these disparities. Further, there were for some reason no mandatory "safety margins" in tsunami level precautions to offset modelling inaccuracies, unlike in precautions for the earthquake ground shock – eventhough computational models for tsunami levels were and remain much less accurate than the ground shock models. Although by 2000s the shortcomings of tsunami analysis like the one done for Dai-ichi were already well-known, a methodologically-flawed further analysis by TEPCO in 2010 failed to introduce any new recommendations – against the published opinions of their own scientists. The cost of relocating the diesel generators higher up in the building would have been just in the hundreds of thousands of dollars, rather than millions.
BurningFrog 11y ago
Remember that this was the biggest earthquake to hit Japan in over 1000 years of known quake history. It hit in a pretty ideal spot to generate a big tsunami at the reactor site. Maybe the reactors "should" have been engineered to handle this situation anyway, but keep in mind that this event is an extreme outlier.

by nickff 11y ago

maxerickson 11y ago

Here's a key phrase from the abstract that suggests more than hindsight bias is involved in the report: The Fukushima accident was preventable, if international best practices and standards had been followed, if there had been international reviews, and had common sense prevailed in the interpretation of pre-existing geological and hydrodynamic findings. Another one: Three, the hazard analysis to calculate the maximum probable tsunami at Dai-ichi appeared to have had methodological mistakes, which almost nobody experienced in tsunami engineering would have made. So there is sense in which they are pretty strongly pointing at regulatory failure.

Shivetya 11y ago
When it was built or after? This plant was built in the early eighties. The article doesn't state if it violated the ideals of then or more recent knowledge.
- maxerickson 11y ago
  The comparison to Onagawa makes it clear enough that they are talking about when it was built. They wouldn't have had so much more experience in 1968 than when they did the early design work for Fukushima Dai-ichi.
- samstave 11y ago
  Fukushima was built in 1967... and was based on an even slightly older GE plant design. Or were you talking about the other plant?
ChuckMcM 11y ago
I'm not sure if you agree that the findings are unsustainable or not. Two things that the IAEA had established were that 1) Fukishima survived the earthquake as designed, and was in the process of shutting down when the tsunami hit. 2) The tsunami disabled primary and backup power to the cooling systems which was the proximate cause of the failure. Further, at the time of its commissioning, the tsunami it experienced was accepted by the best engineering data at the time to be impossible. You can make the argument that over time as more data became available the regulatory agency should have required additional upgrades to cover the larger tsunami risk. There have been plenty of stories about regulatory capture between TEPCO and the regulators which prevented best practices from being followed. A lot of retrofits had been installed over time and that no doubt contributed to its survival of the earthquake.
- maxerickson 11y ago
  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.
  - ChuckMcM 11y ago
    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.pdf https://www.iaea.org/sites/default/files/protection040912.pd...
logicallee 11y ago
The next nuclear accident that will occur in the world is 100% preventable, and without any hindsight bias I will tell you exactly how... after it occurs. /s (seriously, if you want me to take a claim seriously that accidents are preventable, talk about what we are doing wrong today, not in the past.)
- makomk 11y ago
  Engineers at TEPCO did tell them what they were doing wrong at Fukushima Daiichi. They were ignored: "In 2008, TEPCO did two sets of calculations, one based on the Headquarters for Earthquake Research Promotion (HERP) fault models which suggested tsunami height estimates of 8.4–10.2 m relative to the reference sea level. Another one based on Satake et al. [47] produced 8.7–9.2 m tsunami height estimates which were also apparently dismissed [32]. TEPCO ignored them, claiming there was ‘no wave source model’ for the former, and it required a tsunami deposit investigation for the latter [32]. In 2009, new estimates using updated bathymetry and tidal data yielded a 6.1 m tsunami height [12,32]. This was not followed-up and was only reported to Japan's Nuclear and Industrial Safety Agency (NISA) on 7 March 2011 [48]. A post-event study [48] asserts that ‘a senior NISA official has confirmed to us that NISA neither ‘commissioned nor reviewed’ numerical studies of tsunami run-up at Fukushima Daiichi’." The reason you only hear about these issues after an accident occurs is not because they could only be predicted in hindsight, but because no-one cared about the predictions until after the accident.
  - logicallee 11y ago
    if our title read "Nuclear power plants are still being run recklessly, and the next Fukushima-like accident is likely 100% preventable today" it would get my attention, and I would read what the claims that we need to be doing are. small statistical disagreements about experts on the other hand, are hard to take as seriously.
    - btilly 11y ago
      The thing is that those are not small statistical disagreements. The maximum tsunami+tide they designed for was 5m. Design parameters said that you should have a wall 2x what you think you need so they built a 10m (about 30 foot) wall. Two independent teams came up with realistic tsunamis near that 10m wall (one over and one under), so they should have changed their wall requirement up substantially. But they argued themselves into believing that 6m was a realistic maximum then did nothing. Their estimates were also out of line with actual tsunamis experienced elsewhere. Tsunamis in recent decades from earthquakes similar to the ones that they knew could hit the area have ranged from 3-30m. Even a 7.0 earthquake managed to create a 12m tsunami in New Guinea. The actual tsunami was 13m. The most telling point is how the response afterwards has shown lessons not learned. For example The United States National Research Council of the National Academies had a 21 person panel conduct 18 months of interviews with a wide variety of technical experts on how the disaster could be prevented here. NOT ONE of the members of the panel or the people interviewed was an expert on tsunamis. The author's of the paper clearly believe that if you're studying the aftermath of a tsunami, you should at least talk to someone who studies tsunamis... If the paper is correct, it is a question of time until somewhere in the world we have another entirely preventable major disaster because local officials underestimate tsunami threats that current knowledge is more than sufficient to predict. Of course enough things can go wrong that the next big disaster won't be that. But that preventable disaster is coming...

PaulHoule 11y ago

If you read closely you see that the accident was so bad because of one simple problem. If a nuclear reactor has a cooling failure, the fuel will eventually heat up and then melt down. To prevent this you have to keep water circulating around the reactor core. It doesn't take a huge amount of energy to do this, but it does take some. If the power goes out at the station and they can't get emergency power, the outcome is very bad. If they had spent maybe $300k or so they could have moved the emergency generators a little bit higher up. With that investment there still would have been serious damage to the plant but only a very limited release of radioactivity because the fuel integrity and the coarse integrity of the plant would have been protected.

deleted 11y ago
[deleted]
nickff 11y ago
I have read that many times, and it makes some sense. The issue with this line of reasoning is that the move would be a design change which is not required by the specification (as I have read and understood it), which would have been seen as unnecessary waste at the time. A study which I would find more important and useful than the one here would be a cost/benefit analysis of increasing all specifications relating to all (similar) low probability events. In other words, if you had been a designer of the plant looking to spend an extra $500000 to make the plant safer, would you have spent it on moving the generators? How many other contingencies would have been higher priorities than this one (if any)? What would be the total cost/benefit of applying this heightened standard to all new facilities? Would this be statistical murder?
- PaulHoule 11y ago
  When you consider that a nuclear plant costs billions of USD and that billions of USD of damage has been done, the $500,000 upgrade to the generators is a slam dunk. Also based on recent projections, the probability of a tsunami event of that severity was 80% for the next few decades, so it is a no brainer -- particularly when you consider that the nuclear industry worldwide has been set back 20 or 40 years at least by this incident. The NRC has had modernization plans at U.S. reactors that have spent much more than this. For instance the hydrogen bubble formation in that kind of BWR was well known here and reactors in the U.S. have had features added (dependent on a power source) that would get rid of it.

vesinisa 11y ago

The authors argue that there were very serious and repeated shortcomings in the methodology used to estimate the highest possible flooding caused by a tsunami. The plant was designed for 6-meter tsunami from an M=7.5 earthquake, but what actually hit them was a 13-meter tsunami from an M=9.0 quake. I understood it's international standard practice to consider worst-case events from historical record spanning thousands of years in nuclear plant risk analysis, and it is known that almost as strong earthquakes hit Japan in 1933 (M=8.5) and 869 (M=8.6), for example. A plant by a different company just 100 km north of Dai-ichi was built for a 13-meter tsunami, so there was little consistency in what preparations the tsunami analysis actually induced, and the regulator seems to have been indifferent to these disparities. Further, there were for some reason no mandatory "safety margins" in tsunami level precautions to offset modelling inaccuracies, unlike in precautions for the earthquake ground shock – eventhough computational models for tsunami levels were and remain much less accurate than the ground shock models. Although by 2000s the shortcomings of tsunami analysis like the one done for Dai-ichi were already well-known, a methodologically-flawed further analysis by TEPCO in 2010 failed to introduce any new recommendations – against the published opinions of their own scientists. The cost of relocating the diesel generators higher up in the building would have been just in the hundreds of thousands of dollars, rather than millions.

BurningFrog 11y ago

Remember that this was the biggest earthquake to hit Japan in over 1000 years of known quake history. It hit in a pretty ideal spot to generate a big tsunami at the reactor site. Maybe the reactors "should" have been engineered to handle this situation anyway, but keep in mind that this event is an extreme outlier.