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Re: In-flight radiation doses
Russ,
You may what to tell your friend to visit the Health
Physics Society's "Ask the Experts" Web site at
http://hps.org/publicinformation/ate/
--- Russ Johnson <rujohnso@nmsu.edu> wrote:
> I think the primary issue was more along the lines
> of chronic occupational exposure to flight crews,
> not a one-time event. The question I got in class
> was from a French grad student who had recently
> arrived on campus. She was pregnant at the time and
> wondered if there was an issue involving fetal dose.
> I thought it was an appropriate question, so I went
> in search of an answer. But if it is not an issue, I
> would be most happy to tell her so.
> -Russ
>
> ?????? ?? wrote:
>
> > Well, The last Concord plane has been grounded
> already, so my remark is of theoretical value only
> (if any...). I can't understand the reason why those
> Concords were ordered to lower altitude in the event
> of a solar flare. While changing altitude from
> about 80000 feet to 39000 feet, lowering the
> exposure to half the dose per unit of time, they had
> to cut the speed and doubling the flight
> (=exposure)time . The net change in radiation
> exposure would be about 0.I have raised that
> question to FAA men during the IRPA 2000 they gave
> me a twisted answer that the most logical part of it
> was that it only happaned once and that Concord
> flights are phasing out anyway...
> >
> > Dov (Dubi) Brickner MD
> > Beer-Sheva ISRAEL
> >
> > -----Original Message-----
> > From: owner-radsafe@list.vanderbilt.edu
> [mailto:owner-radsafe@list.vanderbilt.edu] On Behalf
> Of Franz Schoenhofer
> > Sent: Friday, July 09, 2004 12:37 PM
> > To: John Jacobus; radsafe@list.vanderbilt.edu
> > Subject: In-flight radiation doses
> >
> > There was a paper on this topic in Health Physics
> about 10 years ago. Since
> > the Concord(e)s flew so high up (wasn't it 18 000
> meters?), that the doses
> > from solar flares were regarded as not negligible,
> a measurement device was
> > working automatically during flight to warn in the
> case of elevated doses,
> > whereupon the plane flew to a lower altitude.
> >
> > More on this topic:
> >
> > There is still little known about the exact doses
> from cosmic rays,
> > especially about the quality factors for larger
> particles. The neutron
> > component of the cosmic radiation plays an
> important role and even this part
> > of the radiation can only be measured with more
> sophisticated
> > instrumentation than a TLD dosimeter or a Geiger
> counter would be, not to
> > talk about the other components.
> >
> > In light of this fact it is difficult for me to
> understand, that - though
> > radiation doses cannot be easily and/or exactly
> determined - there exist
> > regulations, depending on radiation doses. The
> European Union Directive
> > obliges the member states to install regulations
> for in-flight doses. The
> > regulations of member states which I know use the
> concept, which is used
> > also for regulations with respect to Naturally
> Occurring Radioactive
> > Material (NORM): Members of the public are not
> supposed to receive doses
> > above 1 mSv/y. If professional of the flight crew
> (which are not regarded as
> > radiation workers!) probably or likely are to
> exceed 6 mSv/y, they have to
> > be monitored. The employer has to care for
> reduction of the doses. In any
> > case 20 mSv/y must not be exceeded.
> >
> > Regarding "monitoring" of flight crews: Since it
> is not possible to have a
> > simple device like a TLD for measurement (see
> above), a totally different
> > approach has to be chosen:
> >
> > Despite the above described inherent problems to
> accurately determine a
> > "real" dose, really a lot of research has been
> done on the aspect of
> > in-flight doses, both on behalf of air lines,
> national organisations and
> > international organisations like the European
> Union. The basic facts are
> > relatively well known, one being the variation of
> cosmic radiation intensity
> > with elevation, latitude, season etc. So an
> overall pattern is known. The
> > sun activity is very well monitored by astronomers
> and the cycles governing
> > it on a large scale is well known. I know of
> British Airways that they use
> > computers to calculate the expected doses
> according to the flight routes. A
> > few BA airplanes carry measurement devices and can
> transmit instantly
> > changes like big solar flares. This enables BA to
> assign doses to every
> > single member of a crew. Crew members approaching
> their 6 mSv/y will be
> > assigned to flights with lower expected doses.
> According to estimates from
> > BA the crew of long-haul flights will normally
> receive between 5 and 8
> > mSv/y, so the problem is not really dramatic and
> can be rather easily
> > overcome, making special "personal" monitoring
> unnecessary. Crews working on
> > short-haul flights are according to several
> national studies not at all at
> > risk to exceed 6mSv/y.
> >
> > There is a web-site, which you can use to
> calculate your dose on your next
> > flight, but I do not have the address at hand.
> Anybody interested in details
> > is welcome to contact me and I will do my best to
> find material in my still
> > unsorted records. An alternative is of course to
> use Google or another
> > Search Engine ("in-flight radiation"), though they
> usually do not yield
> > highly scientific information.
> >
> > Best regards,
> >
> > Franz
> >
> >
>
--------------------------------------------------------------------------
> >
> > -----Ursprüngliche Nachricht-----
> > Von: owner-radsafe@list.vanderbilt.edu
> > [mailto:owner-radsafe@list.vanderbilt.edu]Im
> Auftrag von John Jacobus
> > Gesendet: Freitag, 09. Juli 2004 15:45
> > An: radsafe@list.vanderbilt.edu
> > Betreff: Re: CNN article
> >
> > I believe that the Concorde jetliners had
> pressurized
> > ion chambers in the crew's cabin to provide
> real-time
> > exposure results. If a solar event occurred, the
> crew
> > were supposed to reduce their altitude, which I
> > believe only occurred once. I have yet to find
> any
> > indication if the exposure data was every
> recorded.
> >
> > --- JGinniver@AOL.COM wrote:
> > >
> > > In a message dated 7/7/04 1:04:47 am,
> > > rujohnso@nmsu.edu writes:
> > >
> > >
> > > > I'm curious now what the actual doses are to
> > > full-time international
> > > > airline crews. Does anyone know, per flight or
> per
> > > annum? I've been asked this
> > > > question before in the radiation safety class
> I
> > > teach, but I don't know. If
> > > > european agencies monitor crew doses, then
> they
> > > must fly with TLD or similar
> > > > badges.
> > > >
> > >
> > > There is quite a good summary by the UK National
> > > Radiological Protection
> > > Board at the following URL
> > >
> > >
> >
>
http://www.nrpb.org/publications/bulletin/no4/editorial.htm
> > >
> > > It as my understanding that doses to aircrew
> could
> > > not be accurately
> > > estimated using simple passive detectors such as
> > > TLDs. Instead special monitoring
> > > equipment has been developed by the NRPB which
> is
>
=== message truncated ===
=====
+++++++++++++++++++
"To be persuasive, we must be believable,
To be believable, we must be credible,
To be credible, we must be truthful."
Edward R. Murrow
-- John
John Jacobus, MS
Certified Health Physicist
e-mail: crispy_bird@yahoo.com
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