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RE: In-flight radiation doses
The reason that they were ordered to fly at a lower
altitude was that the exposures during a solar flare
are higher than the typical doses at the higher
altitude. The comparison with flying at the higher
altitude for less time versus lower altitude for
longer time is only true during non-solar flare
intervals.
--- ×.ר×.×§× ×¨ ×.×. <brickner@zahav.net.il> 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
> > carried on the aircraft to
> > provide dosimetric information and that by using
> > different routes/flight
> > paths/altitudes it is possible to estimate the
> doses
> > to aircrew.
> >
> > Regards,
> > Julian
> >
>
>
> =====
> +++++++++++++++++++
> "To be persuasive, we must be believable,
> To be believable, we must be credible,
> To be credible, we must be truthful."
> Edward R. Murrow
>
=== 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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