Thursday, 9 June 2011

RADIATION ON #ISHINOMAKI TRIP DEBRIEFING: DON'T GO TO DENVER

There really is too much going on with Quakebook, Ishinomaki and the cover life to waste time posting here, but Our Man has to do something in case his handlers lose interest and do something crazy like email pictures of themselves in briefs or run for Congress or something.

So, here's something. Our Man strapped the bento Geiger counter to his Toyota Harrier and jumped all over data (when he remembered to press "start" on the inboard computer, ahem) on his mercy dash up to Ishinomaki the other day. The long and the short of it was: He got more radiation in Fukushima than anywhere else in Tohoku (duhhh), elevated levels in Abiko and nothing to write home about in the tsunami-hit areas. Radiation wise. But wherever he went, Our Man was safer than if he lived in Denver.

What does it all mean to laymen? Dunno, preferring to lay women himself (leave it out - ed): But here is an intercepted, decyphered, steamed microfiche from Chief Petty Science Officer Agent J (embedded deep within safecast.org)


Tip: If you can't read it, you might try squinting real hard. Or you could click on it and it might get a bit bigger (as the Congressman said to the porn star).

Or read it here, ahem:

Got back in one piece - the readings ranged from 0.07 uS in Ishinomaki to 0.59 uS 55km due west of Fukushima Dai Ichi. The Abiko 7-11 was 0.29.

Yes, I was following your progress via Twitter. 
Well done.


Are these measurements micro or milli sieverts btw?

The numbers are micro Seiverts. Normally I would next add a caution about the unreliability of converting the output of a Geiger counter to Seiverts because there are so many variables that can thwart a valid calculation. But in this case we're on firm ground: The unit inside the bGeigie is calibrated for the same isotope (cesium 137) that is the main contaminant we
find outdoors hereabouts. (There is also some cesium 134 around but its energy is similar so its presence doesn't spoil the calibration validity.)

I would say that the plus/minus 15% uncertainty of the detector itself is the main caveat for your readings. Good work Agent Nabiko.

What do these figures mean that a layman like me could make sense of (and tell others)?

We will need to compare the data you collected to previous trips to see if the places are the same, but based on your descriptions, it seems that levels have fallen significantly. That would be good news.

Speaking more generally, the levels you encountered are still most definitely "elevated" compared to what was previously considered "normal background" for Japan. What you reported in Ishinomaki (0.07uSv/hr) is likely not much different than a year ago. Your reading from Fukushima-ken (0.59uSv/hr) is obviously well above what is natural for that area. (But still substantially lower than some uncontaminated places on Earth.)

For comparison, the average annual effective dose for Americans from all sources (sorry U.S. data is the most freely available) is 6200uSv, about half of it from natural sources. A person just sitting outside near where you measured the highest level would absorb 5172uSv in a year if conditions don't change; about five-thirds as much as the average American and a bit more than half what a typical resident of Denver gets.

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