Thursday, March 17, 2011

Blog March 17 2011 Japanese Reactor Disaster

Thoughts on the Japanese reactor disaster in response to a query from my daughter, Christina Carlson who lives on the West coast.

I have followed the catastrophe in Japan with deep interest. It confirmed my feelings that nuclear reactors are a bad idea. I have always felt that when a highly complex system with dangerous outcomes meet unanticipated stresses, it has a risk of failing. That happens when dams break, Titanics sink, and Chernobyl/3 Mile Island/ and Japanese reactors fail. Most industrial backers will shy away from the costs of a well designed reactor that anticipates 9.0 earthquakes and 30 foot tsunamis or a terrorist attack, say a jet slamming into a reactor.

That is my first impression of my take on this bad outcome. I am concerned that two days ago there was a report that one of reactors “may” have had a partial meltdown with a release of 400 milliSieverts per hour. Since that’s about 40 roentgens per hour, just one day’s exposure would be an LD-50 [mean lethal dose] dose in which half of those receiving such a dose (400-500 R or 4 to 5 Sv) would die of radiation sickness. Fortunately, the efforts to pour sea water every day are working to some extent because within an hour or so the emitted dose was back to a fraction of that rate (1-10 mSv/hr). So the workers in the nuclear reactors are not dying of radiation sickness the way the Chernobyl workers did where the release was on-going because they had no way to flood the reactor for weeks and eventually had to entomb it in concrete.

The third impression is more difficult for me to assess. Low doses do cause small amounts of mutational damage (but not radiation sickness) so worldwide the effect will be trivial like the Chernobyl disaster for the US or most of the world. The regions that got clobbered were in Ukraine and by wind drift to Lapland and other parts of Europe. I still remember how disturbed I was when you were in Berlin at the time and giving me the doses that were being measured and reported on German radio and TV in Germany. But, of course that was because thousands of roentgens per day were being pumped for about two or three weeks into the atmosphere. I don’t know if the Japanese will contain this faster than the Russians, but I am encouraged that the rate fluctuates. Every time they dump more sea water in, the radiation emission drops by orders of magnitude which is a good thing. What I can’t assess is the condition of the spent rods and their ability to be doused with sea water and the cracked reactor (s). There may be two or more with such cracks.

If I were in Japan and could afford to leave, I would, especially with young children. As far as living on the West coast, I don’t see any way it would be possible for such diluted radioactive debris to fall out on coastal cities in worrisome amounts. It would be similar to nuclear fallout from weapons testing at the worst and those tossed the radioactive debris into the stratosphere which the Japanese reactors can’t do.
A last thought. The potassium iodide [ KI] tablets are not very useful on the west coast because I131 or other isotopes will be minuscule in dilution hitting the west coast. Most of that KI risk comes from drinking milk of cows that eat grass that grows on Iodine contaminated soil. It would be easier to monitor the milk and not use it if it’s above a certain low level. The KI had it been used in Ukraine in the first few days of heavy radiation they could have saved lots of children from thyroid cancers.

Radiation damage is proportional to dose. So a mSv is 0.1 R which is a chest x-ray dose (or for some machines, ten chest x-rays worth). The individual risk is very low of cancer and zero for any symptoms of radiation sickness. But a dose of 100 R or 1 Sv is very high and will cause symptoms of radiation sickness. But radiation decays inversely to the square of the distance so if you are several miles away from a 100 r release the amount getting that far will be in the small mSv range (about 1 to 10 mSv). What all this means is that anyone within a few feet of the reactor will be dangerously at risk if not heavily protected with lead shielding. The workers there are at high risk. But since no one should be in a radius of 12 miles or so, those outside that zone will be at relatively low risk unless a Chernoby-l like explosion heaves a plume into the stratosphere which drifts and rains down radioactive debris. That’s what I’ve been nervous about because of the unprotected spent fuel which is filled with radioactive isotopes.

No comments: