Tuesday, March 22, 2011

More Radiation Stuff From Japan

First, I do have a life of sorts. My trip today was postponed, but I have been shopping, went to the laundry, hung out at the dock with buddies, went to a meeting and done a few other things today. I am fascinated with the goings on in Japan, so I have been digging up stuff instead of watching the tube.

The radiation map thing and its thinly veiled allegation that there is a Japanese government cover up going on, has been on my mind. I found plenty of data on radiation readings including fallout for Iodine (I 131) and Cesium (Cs 137). The readings are of course in new units which means more calculations to see what they mean.

These two radioactive Isotopes have half lives, I 131 is 8 days and Cs 137 is 30.17 years, per wikipedia. Cs 137 is the nastier of the two. This link has the fallout readings for most of Japan, but is not complete for two prefectures because of limited access following the Earthquake.

Ibaraki has the highest fallout with 85,000 I 131 and 12,000 Cs 137 recorded as MBq/KM2. A MBq is MegaBecquerel and KM2 is kilometers squared. The IAEA report is in meters squared, so one KM2 is equal to 1,000,000 M2. That makes the conversion easy since MBq/KM2 is equal to Bq/M2. But, the IAEA report is in MBq/M2, so we have to divide the 12,000 by a million which is 0.012 MBq/M2.

So for the nasty Cs 137, the fallout is 0.012 Bq/M2. There is also I 131 which would be 0.08 MBq/M2 for at total of about 0.1 MBq for simplicity. Now what does that mean? A Bq is one pop or nucleus decay per second. That really does not mean a lot until it is converted to Severts, damaging absorbed radiation. Since I was not there when the IAEA guys did the test, I will ratio the high reading in the report 160 microseverts and 0.9 MBq/M2 to get about 17 microseverts/hr per meter squared.

Now if that wasn't complicated enough, I 131 has a half life of 8 days, so every 8 days the pops drop by half. 80,000 today, 40,000 in 8 days, 20,000 in 16 days and 10,000 in 24 days. So in a couple months, only Cs 137 is really a concern. Then the fallout radiation drops to 1.7 microseverts per hour. That would be 14,900 microseverts per year. Unless you happen to be a Brazilian airline pilot, that is high (see the chart and radiation readings on this link for Ibaraki.)

That was simple enough, but wait! There is more! From Wikipedia, "Health officials have predicted that over the next 70 years there will be a 2% increase in cancer rates in much of the population which was exposed to the 5–12 EBq (depending on source) of radioactive contamination released from the reactor." (Re: Chernobyl). So what the hell is an EBq? That is an exabecquerel which is 10e18 Becquerel or 1,000,000 MBq! So if there is a 2% increase in cancer rates for 12,000,000 MBq, what is the increase for 0.1 MBq/M2? Don't know. It don't work like a linear relationship. That is why we underpay the scientist types and have to trust our governments. I doubt that anyone on CNN, FOX or the BBC has a clue either! I wouldn't drink any milk or eat any leafy green veggies from that area until next year. Once the rain washes the Cs 137 into the soil, things will be different. Stay tuned!

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