The Panic Over Fukushima

An anonymous reader points out an article in the Wall Street Journal about how irrational fear of nuclear reactors made people worry much more about last year's incident at Fukushima than they should have. Quoting: "Denver has particularly high natural radioactivity. It comes primarily from radioactive radon gas, emitted from tiny concentrations of uranium found in local granite. If you live there, you get, on average, an extra dose of .3 rem of radiation per year (on top of the .62 rem that the average American absorbs annually from various sources). A rem is the unit of measure used to gauge radiation damage to human tissue. ... Now consider the most famous victim of the March 2011 tsunami in Japan: the Fukushima Daiichi nuclear power plant. Two workers at the reactor were killed by the tsunami, which is believed to have been 50 feet high at the site. But over the following weeks and months, the fear grew that the ultimate victims of this damaged nuke would number in the thousands or tens of thousands. The 'hot spots' in Japan that frightened many people showed radiation at the level of .1 rem, a number quite small compared with the average excess dose that people happily live with in Denver. What explains the disparity? Why this enormous difference in what is considered an acceptable level of exposure to radiation?"

Comments

I'm still blown away

[93 Escort Wagon]

Not by the Fukushima thing - but by the fact that the tsunami was 50 feet high at the plant. I understand how it can happen; but that is truly awesome (in the literal sense of the word).

Re:I'm still blown away

[AmiMoJo]

At Fukushima, it looks like they had a dozen or so backup generators on the theory that if one has a (say) 1 in 10 chance of failing, then the chance of all of them failing is 1 in 10^12. But nearly all of them were located in the same place, so a single event (a tsunami) which took out one generator took out all of them. Having multiple generators situated this way did not provide redundancy because they weren't vulnerable to independent events. They were vulnerable to the same event.

What they needed to do was put the generators in different locations, with different fuel sources, probably even different manufacturers and fuel types. That way an event which affected one would not affect the others, making their vulnerabilities independent events. The generators at reactors 5-6 were located further uphill, and thus survived the tsunami intact and were able to keep the fuel storage tanks there cooled.

They did actually do that. TEPCO had plenty of reserve equipment stored at a location about 50KM from the plant, so it would cover both Fukushima Daiichi and Daini. Unfortunately infrastructure damage prevented them getting the equipment to Daiichi, even by helicopter. The plant itself was damaged so that even if the spare generators had been located up on a hill it wouldn't really have helped much anyway because there was no quick way of attaching them to the cooling system. The entire plant design was flawed in that respect.

The cooling system was also damaged by the earthquake and tsunami. Valves failed and even though they had power available (taking car batteries out of staff vehicles) they couldn't operate them.

This is only now coming to light and data is analysed, CCTV footage released and the wrecked plant explored. The initial assumption that there was a single point of failure and that the tsunami caused all the damage has turned out to be wrong.