[ RadSafe ] FW: Reporter's question about lower limits ofdetection; inhalation dose

Busby, Chris C.Busby at ulster.ac.uk
Wed Aug 10 04:52:15 CDT 2011

Dear Steven
Yes, of course. And I have made it. Its not difficult, you have 24m3 a day inhalation (ICRP Refernce Man) and then use the public inhalation coefficients you prefer. Try Radiation Toolbox. The ICRP effective dose for the Cs137 pops out. But lets not open that box, please. The Health Physics people will say: trivial dose. The ECRR analysis is different and we musnt forget that Cs-137 is just a flag for all the other crap. We will have to wait and see the cancer rates etc over the next 10 years, probably 5 yeasr.

-----Original Message-----
From: radsafe-bounces at agni.phys.iit.edu on behalf of Steven Dapra
Sent: Wed 10/08/2011 02:03
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] FW: Reporter's question about lower limits ofdetection
Aug. 9

         Let's all take a deep breath. . . .  Forget about filters, 
their efficiency, miles driven, and all the rest of it.

         Below, Chris Busby says, "The [car] filters showed between 
1.2 and 3Bq per cu metre of Cs-137."  Right or wrong, let's stick with that.

         Take such a filter and fasten it to the wall three feet 
above the floor.  Ten feet from that filter, have reference man sit 
in a chair facing the filter 24 h per d, for 365 d.  At the end of 
the year, how much radiation exposure will reference man have 
received from the 1.2 to 3Bq per cubic meter of Cs-137 that is in or 
on the filter?

         We need a specific figure, or at least a range within three 
sigma.  I am assuming that it is possible to make such a 
calculation.  If the answer is at or less than normal background (say 
400 mrem), I would have to say that this entire argument about car 
filters is a waste of time.

         Can such a calculation be made?

Steven Dapra

At 06:39 AM 8/7/2011, you wrote:

>Dear Radsafers,
>It was my intention to show that the levels in Japan in air were not 
>trivial. I do know this because I have measured it in several car 
>filters for which the engine size is known and the number of km 
>driven after the incident is known. The efficiency of the filters is 
>assumed to be 50% but this is not known for sure although I have 
>asked the manufacturers. The filters showed between 1.2 and 3Bq per 
>cu metre of Cs-137. This can be compared with the attached data from 
>Harwell. The results were from my lab and also from Harwell who we 
>paid to do the analysis.
>I am interested to learn that the levels were higher in the USA 
>during the atmospheric tests than in the UK: Stewart Farber says 
>100mBq/m3. Probably because the US is where many of the tests were done.
>But my argument was about Japan, not levels in the USA. I am quite 
>aware that the levels in the USA were far smaller, as we would 
>expect. But i see a maximum of 0.116pCi is 4.29mBq/m3 The average is 
>0.7mBq/m3. Compare with the graph attached. But I think it depends 
>on where you live, doesnt it? And what other stuff comes along as a passenger.


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