4 ms·

It's very hard to estimate the probability of very rare events like tsunamis and earthquakes, so you kind of have to use heuristics to get a reasonable "design

by alricb 11y ago

It's very hard to estimate the probability of very rare events like tsunamis and earthquakes, so you kind of have to use heuristics to get a reasonable "design basis" event. Then you design your system to survive said event. The argument the authors make is that the event was improperly chosen (too low). A proper choice of event would have led TEPCo to conclude that they had to mitigate the danger posed by a higher flood line, by, for instance, moving the generators.

nickff 11y ago
This thinking is using hindsight bias. If you had been more cautious with respect to this one type of event at this one plant, you would have prevented this problem at a low cost. The problem is that only really tells you that 'if you know what's going to happen, you can do a really good job planning for it', which is rather obvious and completely useless. My point is that if you were to have been more cautious in the overall specification for the plant (because, again, the plant was never designed to survive the type of event it was subjected to,) it is not clear whether the generators would have been moved (as that may not have been a high priority compared to other improvements), or even if they had, what the cost/benefit ratio would be. You have to remember that there may be many other events which may have appeared more likely than large earthquakes and tsunamis, and those would probably have been seen as more cost-effective safety enhancements, and would have been waste. In addition, this heightened standard would be applied to all the power plants subject to similar regulation, which would have been further waste. The important question is not what the cost/benefit ratio for moving generators at Fukuhima before the tsunami would have been, but what the cost/benefit ratio for taking precautions against all events of similar likelihood and impact in would be for all power plants (or even all infrastructure) would be.
- alricb 11y ago
  The value used to determine the Design Basis Flood is a 10000 year recurrence. Over a 100 year lifespan, there is around a 1% chance of that flood happening. The consequences of loss of all power including backups is the loss of the plant + huge evacuation costs and possible loss of life. $1M is very cheap to protect a multi-billion plant in this context.

by alricb 11y ago

nickff 11y ago

This thinking is using hindsight bias. If you had been more cautious with respect to this one type of event at this one plant, you would have prevented this problem at a low cost. The problem is that only really tells you that 'if you know what's going to happen, you can do a really good job planning for it', which is rather obvious and completely useless. My point is that if you were to have been more cautious in the overall specification for the plant (because, again, the plant was never designed to survive the type of event it was subjected to,) it is not clear whether the generators would have been moved (as that may not have been a high priority compared to other improvements), or even if they had, what the cost/benefit ratio would be. You have to remember that there may be many other events which may have appeared more likely than large earthquakes and tsunamis, and those would probably have been seen as more cost-effective safety enhancements, and would have been waste. In addition, this heightened standard would be applied to all the power plants subject to similar regulation, which would have been further waste. The important question is not what the cost/benefit ratio for moving generators at Fukuhima before the tsunami would have been, but what the cost/benefit ratio for taking precautions against all events of similar likelihood and impact in would be for all power plants (or even all infrastructure) would be.

alricb 11y ago
The value used to determine the Design Basis Flood is a 10000 year recurrence. Over a 100 year lifespan, there is around a 1% chance of that flood happening. The consequences of loss of all power including backups is the loss of the plant + huge evacuation costs and possible loss of life. $1M is very cheap to protect a multi-billion plant in this context.