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Higher than usual reading this morning from Fremont, CA
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Author:  Morellio [ Mon Oct 13, 2014 1:29 pm ]
Post subject:  Readings dipped over the weekend, then surged back to 750cpm

Readings fell on my station in Fremont and were no longer increasing, settling to 400-550cpm over the weekend. Overnight however, my 'station' is back up to 750cpm. I honestly can't say this is related to Fukushima or anything else specifically, only that I'm seeing another increase. Without identifying the isotopes on my filter, all I can be certain of is that I'm seeing in increase in what looks like beta emitters, and that there's a very specific pattern in the time of day I'm seeing spikes that match very closely to the Fresno, CA EPA site.

Increases only seem to occur at night, and whatever I'm collecting is most concentrated at around 10am after my filter has been sucking it up all evening. After 10am whatever release was happening seems to be over and counts level off and fall to their lowest cpm at around 5pm. Could it be wind patterns? Some local construction or industrial facility? The position of the moon? Radioactive space dust? Aliens? ;)

I do have a real question though..

Why do levels fall over the course of 7-8 hours? Radionuclides with a half life of that time are pretty exotic. Are the particles being eventually pulled through my filter, or are they actually decaying to more stable configurations? I guess knowing what emitters I'm seeing would hold the key.

Polimaster in the US seems to almost be a joke though, it's been really frustrating to deal with them as a private citizen. They seem to be geared more towards supplying police, fire departments, companies, etc with bulk orders of these things.

Author:  GRR [ Tue Oct 14, 2014 10:40 am ]
Post subject:  Re: Higher than usual reading this morning from Fremont, CA

Morellieo,

I've had the same observations regarding high counts at night. Which I think is related to the nuclear industry and their practices. The thinking being that venting at night would be "safer" for the public while they're sleeping.
Who knows how many reactors/systems are being used for industrial, medical, research and military purposes that we will never know about.

Keep smiling, GRR

Author:  Morellio [ Fri Oct 17, 2014 9:11 pm ]
Post subject:  Re: Higher than usual reading this morning from Fremont, CA

Normally at 5PM my counter is reading the lowest values in a 24 hour period, but today it briefly touched just past 900 CPM at almost exactly 5PM. The typical background for months previous was 90 CPM. Much more of this and we will be setting at least a 4 year record. Never imagined I would see values this high.

Author:  Morellio [ Sat Oct 18, 2014 12:12 am ]
Post subject:  Fremont, CA crosses 1000 cpm

Since I wrote my last post it only seems to keep climbing.

http://i.imgur.com/8UJaPT6.jpg

Author:  GRR [ Sat Oct 18, 2014 9:35 am ]
Post subject:  Re: Higher than usual reading this morning from Fremont, CA

Is anyone else in the Bay Area seeing these kind of readings?
Are you changing your air filters everyday?
What's the ambient cpm?

Good luck maybe it's time to move.

Author:  Morellio [ Sat Oct 18, 2014 10:49 am ]
Post subject:  Re: Higher than usual reading this morning from Fremont, CA

Whoa, change them every day? That'd be pretty wasteful, especially with the nature of what I'm seeing. If I turn the air off for 8-10 hours it falls to near background. Or at least, it did when I tried it a few days ago. After getting a reading of 1000 cpm off of it though, yeah it's about time to change it out. Will report back if I see similar numbers with the new filter. Really though, a week or two of air hitting 1000 cpm is not ideal living conditions.

Author:  KingCobra [ Sat Oct 18, 2014 1:18 pm ]
Post subject:  Re: Higher than usual reading this morning from Fremont, CA

I keep a new/newer filter around ready to change if I get a high reding. Then I compare to verify no hot particle trapped in the filter. If I confirm no hot particle, I put the old filter in again. I change my filters out every month or two.

Author:  Pinto [ Sat Oct 18, 2014 3:13 pm ]
Post subject:  Re: Higher than usual reading this morning from Fremont, CA

What about the jet stream from the typhoon in Japan last week?

Author:  Morellio [ Thu Oct 23, 2014 2:56 pm ]
Post subject:  From 700 cpm to 45 in 8-10 hours.

Doesn't seem like this could be anything but radon daughters at this point, I bagged a filter at 700 cpm, and in 8-10 hours later the next morning it was 45 cpm. Wild. o.O

Author:  Morellio [ Fri Nov 14, 2014 2:43 am ]
Post subject:  Re: Higher than usual reading this morning from Fremont, CA

Just an update on this. I've been moving my filter setup to multiple spots around my house for a few days at a time, and nowhere reads higher than that spot near the entry just above the shoe rack. We're on one of the faults branching off the Hayward, and I even tried picking a few spots of cracked concrete that outline it, only finding at most 500 cpm. I'd like to leave it outside but I'm worried about my counter getting stolen, and it's starting to rain.

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