Last week a team from Keio University took one of our geiger counters for a drive. That was a test run for our slightly more elaborate set up, the first test of which happened this weekend. Rather than taping the counter to the window and taking photos (a method which worked fine btw) we’ve developed a bit of a self contained kit we’re calling the bGeigie since it’s something like a little bento box. We dropped off sensor equipment to volunteers in effected areas and took some measurements at schools around Koriyama that we’re a bit concerned about (including one reading of over 50µSv/hr near a kindergarten playground).
This was the highest we reading we took, but we consistently measured 20-30µSv/hr on pavements, etc. and 5-10µSv/hr for soil (typically 5-6 for soil) For air measurement, we have very consitent data as it is measured across the entire ride. In Koriyama it was in the range of 1.2 to 2µSv/hr. We had 3 Medcom devices giving consitently the same value and a Gamma Scout that gave same readings for air. This multiple redundancy was to ensure we didn’t have malfunctioning equipment or a calibration error.
To put those numbers into some perspective, on Sunday April 24th we measured 0.089µSv/hr in the air and 0.227µSv/hr on the ground at in the Silver Lake neighborhood of Los Angeles. Furthermore in Japan, radiation worker dose limits pre-Fukushima were 100 mSv/yr and the dose limit for normal person is 1 mSv/yr. 50µSv/hr is equivalent to annual dosage of 438 mSv which is more than 4x higher than the limit for nuclear radiation workers.
Thanks to Akiba for sharing this and best of luck to all the Safecasters out there!