Radon vs. LNT - [CUT TO] the Chase ("From bug")

["Bjorn Cedervall" <bcradsafers@hotmail.com>]

About 80% of the previous text (including the text that was responded to) by 
Dr. Per Drake, PEDR@ringhals.vattenfall.se, was killed by the "from bug". 
Below is the text with the "from" replaced by the word "BUG".

Bjorn Cedervall   bcradsafers@hotmail.com
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The first question concerning radon is not precise enough. True we have been 
exposed to low levels of radiation since life began, but the last 50 years 
or so we have made our houses more "air tight" to reduce the cost of 
heating, which in turn has increased the normal background from 1 mSv/year 
to 3 mSv/year and we have also added medical examinations amounting to appr. 
1 mSv/year. A factor 4 might be a disadvantage and is equivalent to or 
higher than the average increase from irradiation in radiological work such 
as X-ray at hospitals, air traffic, nuclear workers.

The question concerning unidirectional irradiation is dealt with in ICRP 74 
e.g Figures 68 and 69.

BUG  Figure 69 it can be seen that a dosemeter on the front of the trunk 
will give a good estimate of the effective dose for all irradiation 
geometries in a nuclear power plant (photon energy average well above 100 
keV). In general the radiation fields in a power plant tends to be more 
isotropic than most people are aware of.

For irradiation from the rear an additional dosemeter worn on the rear side 
of the torso combined with an algorithm for combining the readings of the 
two dosemeters (such as (2*Dmax + Dmin)/3 ) will improve the accuracy. For 
irradiation from underfoot or overhead the effective dose is overestimated 
from the reading of such a pair of dosemeters. For low energy unidirectional 
fields such as X-ray irradiation the problem is more complicated as a large 
proportion of the radiation is attenuated.

More problematic is the fact that the radiation field close to a source is 
diverging leading to high dose rates for parts of the body close to the 
source. Such cases normally needs to be monitored carefully, usually by 
using multiple dosemeters.

You can find several references in Radiation Protection Dosimetry also for 
neutron irradiation.
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>BUG: Thomas Gleich Harrison <tomh@jove.acs.unt.edu>
>Date: Thu, 9 Mar 2000 04:23:09 -0600 (CST)
>
>You know.. in my very, very humble opinion,.. I do wish we could >simply 
>ignore the so called "radon health threat" that we seem to be >so 
>mesmerized by these days. Other than for a very few specific
>environmental situations such as for uranium miners where it need be 
> >addressed, we have lived with uranium and it's progeny in our 
> >environment for how long now...... and if radon is a "problem", how >are 
>we going to solve it.... "clean up" radon in our air ????  Is >that the 
>suggested solution ????

>But let me ask about another situation... does anybody in the RADSAFE
>community know about any quantitative work that has been done on
>evaluating the gross underestimate for torso dose that can be >expected 
>from single TLD or film badge display orientation to a >unidirectional 
>radiation field ????  It seems to me that due to >variable geometrical 
>orientation and body shielding, wearing a >single film tab anywhere on the 
>upper torso undoubtedly results in a >gross underestimate of realistic 
>whole body doses, possibly >recording only 10% or maybe even less of the 
>actual dose received by >the body in a unidirectional field. I've had 
>several students >express an interest in looking into this problem if in 
>fact it is a >problem.... simply stated, they've asked that if their TLD
>reports a  WB dose of 100 mrem which of course is a minimum dose, is
>there a correction factor which would give them a more realistic WB
>dose estimate?? My only answer is I don't know of one.....
>
>Thanks in advance for yor help.....
>
>Tom Harrison, Ph.D.

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