Re: Radiation Units

["Frohne, Vickie" <VFrohne@BEN.EDU>]

2 R per year is of the same order of magnitude as the 5 R/yr limit for
radiation workers and, from what I recall, is approximately correct for
airline personnel. People living in Denver and other high-altitude locations
also receive more radiation than those living closer to sea level, but not
as much as pilots owing to the greater altitude of aircraft. The situation
is somewhat worse for astronauts. One reason why the shuttle and
International Space Station are in such low orbits is to keep the astronauts
underneath the Van Allen radiation belts and shielded from solar radiation
by Earth's magnetic field. Even so, radiation dosage to astronauts is a
major concern, especially during solar flare and coronal mass ejection
events. Astronauts aren't the only ones with problems. Some kinds of plants
concentrate radioisotpes from the soil. Smokers in particular ingest quite a
bit of this radioactive matter, which tends to lodge in their lungs. A long
time ago, I heard that a flower-seller working near a wall in Grand Central
Station could exceed the 5 R/yr limit (but not by much), just due to the
natural radioisotopes in the granite walls. If true, this tells me that the
5 R/yr limit is about right, meaning that it allows workers to work but
reasonably limits their dosages to the range of "natural" background
radiation.

See http://www.nsc.org/ehc/rad/radbroch.HTM
Also the American Nuclear Society http://www.ans.org/pi/raddosechart/

Vickie

-----Original Message-----
From: Ludwik Kowalski [mailto:kowalskiL@MAIL.MONTCLAIR.EDU]
Sent: Friday, September 06, 2002 11:32 AM
To: PHYS-L@lists.nau.edu
Subject: Re: Radiation Units


Suppose the dose rate in an airplane is 10 times higher than
on the earth surface; this is probably an exaggeration (?). In
that case a pilot flying 24 hrs and 7 days per week would get
~200*10=2000 mR = 2 R per year. What fraction of the year
is a typical pilot flying? I am sure it is well below 10%.
Therefore, my inclination is to think that the additional
dose due to flying is not excessive. But this is only a
Fermi-like guess. Are my assumptions wrong?
Ludwik Kowalski

Bernard Cleyet wrote:

> "..... The "permissible yearly dose," for radiologists
> and other professional people, is now 5 R per year. It
> used to be much larger. The dose most of us receive
> from natural sources (cosmic rays, etc.) is typically
> about 200 mR. For that reason the "legally permissible
> yearly dose" for general population (from man-made
> sources) is now close to 200 mR."
>
> An NPS Physicist has suggested the airlines industry is violating the law
> by subjecting long haul pilots to considerably more than the legally
> permissible annual dose.
>
> He suggested that making pilots radiation workers might be a fix.   I
> suspect  even 5 R permitted is too low.
>
> bc
>
> P.s. The U (UC)  is cautious; their limits are half all those applicable.
>
> Ludwik Kowalski wrote:
>
> > Hi Tina:
> > Let my try to make sense out of it. Historical approach is
> > probably the best in this case. I will not consult books for
> > numbers or conversion factors.
> >
> > 1) It started in 1920's when it was discovered that, on the
> > average, English radiologists died earlier than other doctors.
>
> cut
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