‘Duct tape, wire nets’ were used to mend Fukushima water tanks - worker

[JohnyCanuck]

27. Fukushima and our inability to gauge risk

by Kurt Cobb, Resource Insights Blog

snip

Nuclear power plants are one of the most complex systems ever devised by humans. Complex systems by their very nature have more failure points than simple systems. But this in and of itself is not the problem. Natural systems such as the ocean currents or a rainforest are exceedingly complex. But, they have been around for much longer and their processes have settled into much more predictable patterns. With nuclear power plants, we have little experience to go on in evaluating risks.

Man-made systems not only have much shorter histories to work from, but they can interact with natural systems in unpredictable ways. Recall what happened at the Fukushima nuclear plant: The tsunami was so high that it breached the plant's seawall, flooding emergency diesel generators located in basements, generators that were supposed to power pumps to cool the reactor core and fuel rods in the event of a power outage. Backup batteries for those pumps ran out of power within a day. And, that's when the trouble began that led to hydrogen explosions which damaged buildings--damage that ultimately compromised the fuel rod storage.

Let me quote from an earlier piece of mine, "Calculating calamity: Japan's nuclear accident and the 'antifragile' alternative":

Famed student of risk and probability and author of The Black Swan Nassim Nicholas Taleb tells us that in 2003 Japan's nuclear safety agency set as a goal that fatalities resulting from radiation exposure to civilians living near any nuclear installation in Japan should be no more than one every million years. Eight years after that goal was adopted, it looks like it will be exceeded and perhaps by quite a bit, especially now that radiation is showing up in food and water near the stricken Fukushima Dai-ichi plant. (Keep in mind that "fatalities" refers not just to immediate deaths but also to excess cancer deaths due to radiation exposure which can take years and even decades to show up.)

Taleb writes that it is irresponsible to ask people to rely on the calculation of small probabilities for man-made systems since these probabilities are almost impossible to calculate with any accuracy. (To read his reasoning, see entry 142 on the notebook section of his website entitled "Time to understand a few facts about small probabilities [criminal stupidity of statistical science].&quot ....Calculations for man-made systems that result in incidents occurring every million years should be dismissed on their face as useless.

Furthermore, he notes, models used to calculate such risk tend to underestimate small probabilities. What's worse, the consequences are almost always wildly underestimated as well.

http://resourceinsights.blogspot.com/2013/10/fukushima-and-our-inability-to-gauge.html