[ RadSafe ] Video of Meter - Up to 10,20 µSv in Ichinoseki, Iwate Prefecture 163km from Fukushima Dai-ichi

Rees, Brian G brees at lanl.gov
Mon May 23 12:22:40 CDT 2016

OK, 0.18 or so uSv/hr is a slightly high background, but certainly not a level to get too concerned about.  Since I live at 6800' (2,070 m) I may see that depending on surrounding soil/rock formations.  So it appears that the selection of uSv/hr is appropriate.  Since the dose rate light is blinking on the instrument I doubt if the reading is in some unit of count rate. 

The meter is moved a meter or so horizontally , and a reading of 0.51 uSv/hr is observed.  The 0.51 uSv/hr reading is substantially higher than most backgrounds, and interesting, but again, certainly not a level to get concerned about. 

The time constant of the instrument is long, and the reading does not appear to be a result of electronic interference from something like a radar, or other transmitter.

The meter is then moved closer to the ground - it looks to me to be moved about 1-2' (30-60 cm) closer- and a reading of 10.2 uSv/hr is observed.    The instrument behavior and increase in reading appears to me to be a result of distance, and if you assume it's being held a few cm from the ground, seems to ROUGHLY follow a 1/r2 relationship.  It may be a hot particle,  or similar point-like source.  This is not a dangerous level,  and if the source is at or near ground level, not an external radiation hazard, or a great hazard if ingested (along with however much dirt you'd also be ingesting).   

So, it's not a dangerous situation, it's interesting, and since hot particles containing fission products may be found from time to time as a result of the Fukushima reactor accident, shouldn't be terribly alarming.   

Brian Rees

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Roger Helbig
Sent: Monday, May 23, 2016 6:52 AM
Subject: [ RadSafe ] Video of Meter - Up to 10,20 µSv in Ichinoseki, Iwate Prefecture 163km from Fukushima Dai-ichi


Is this meter or its reader perhaps being mislead due to lack of experience or other cause?

Roger Helbig
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