Re: temporal? variations in background

[epirad@mchsi.com]

Kai,



The dynamics of radon emanation from soil is a bit more 

complicated than displacement.  Bill

> Ted,

> 

> I was talking about radon, not gamma. Radon gets displaced from the pore

> spaces in the soil by the water and gets into the air and into your house.

> 

> The displacement of radon gas is probably part of the reason gamma goes

> down. Remember, 95% of the gamma radiation from the U decay series comes

> from the short lived radon progeny, Bi-214 and Pb-214. Water would also add

> a bit to the shielding. Radon would take a few days to grow back in after

> the soil has dried. Do you notice a lag like that in your gamma readings?

> 

> We do operational checks on our Ventilator radon sniffers before we sell

> them or before I take them on a consulting job. The first few times after a

> rain, I thought we had managed to contaminate the detector, because it was

> counting so high.

> 

> One of these days I'll get organized and run a radon sniffer 24/7 in the

> crawlspace under my house and put the data on the web.

> 

> Regards,

> Kai

> http://www.eic.nu

> 

> ----- Original Message -----

> From: "Ted de Castro" <tdc@xrayted.com>

> To: "Kai Kaletsch" <info@eic.nu>

> Cc: "radsafe" <radsafe@list.vanderbilt.edu>

> Sent: Saturday, September 07, 2002 6:05 PM

> Subject: Re: temporal? variations in background

> 

> 

> > actually no!  wrt gamma background and rain - SOMETIMES you can see a

> > "washout" from the atmosphere for the first 1/2 hour when the rain

> > starts - but in general the more it rains the lower the background -

> > when it stops going down - the ground is saturated.  This also clearly

> > shows in the annual variation - highest JUST before the fall rains and

> > lowest just after the spring storms.

> >

> > I have years of environmental data taken with a very sensitive GM tube

> > (1 x 12 inch active area) that shows this.  Sensitivity 650k counts per

> > mREM - so it certainly has the sensitivity to show this.

> >

> >

> > Kai Kaletsch wrote:

> > >

> > > While the discussion on variation in BG is going on: Does anyone have an

> > > idea of the variations in BG radiation over time? There are short term

> > > spikes in radon after a rain and there are changes in cosmic ray fluxes

> etc.

> > > How do these phenomena affect the long term average exposure?

> > >

> > > For example, if my radiation exposure last year was 3.0 mSv and I live

> in

> > > the same place and do the same things this year, how close to 3.0 mSv

> can I

> > > expect my exposure to be this year?

> > >

> > > How do these temporal variations in natural BG compare with events such

> as

> > > atmospheric weapons testing, Chernobyl etc...?

> > >

> > > Thanks,

> > > Kai

> > > http://www.eic.nu

> > >

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