AW: In-flight radiation doses

["Franz Schoenhofer" <franz.schoenhofer@CHELLO.AT>]

Dov,



I have been working in Austrian Radiation Protection for a long time. I have experienced the Chernobyl accident and all the chaos about food control for compliance with maximum permissible radionuclide concentration levels and finally I ended up in legislation. So I can say with some "authority", that the reasons you question are really easily to understand - at least for an authority: A limit is a limit is a limit. I am sure that there existed a maximum permissible dose rate for the Concord(e) crew. When it was exceeded, they had to go down to lower elevations in order to decrease the dose rate. Like for a soldier or a police man or an employee in whatever factory, the crew has its instructions and has to follow them!!! What about a marksman in a tank, who would refuse to fire a projectile with depleted uranium against an enemy tank, because his personal believe is that this is not correct?



I personally have a feeling that descending to half the elevation will not halve the dose rate, but will be more effective, as well as the speed will not be halved but considerably higher. So it is my personal opinion, not backed by any science behind, that the accumulated dose will be considerably lower. 



We have to face this problem not only in radiation protection, but in any circumstances, where limits are prescribed. Drinking water must not contain more than a certain concentration of nitrate, mercury, arsenic, uranium, chlorinated hydrocarbons etc. etc. You cannot argue, that people might drink water with a five-fold concentration for just a few weeks, then use another source with concentrations far below the limits. 



In the aftermath of the Chernobyl accident almost all European countries set strict limits for the concentration of first I-131 and then Cs-137 in food stuff. The limits were calculated in such a way, that the average person, consuming food with the maximum permissible levels would receive no higher dose, than the one permitted for practices with radionuclides from industry and NPP. This worked well, the actual dose was of course much lower, especially after some time when levels dropped. How would you monitor everybody and everybodies most different foodstuffs and quantities to calculate his doses and tell him that he has to drink only half his usual milk amount for the next three days to lower his Cs-137 intake? 



There are hardly any examples known to me, where limits include a time component and allow for time averaging. From my own work I remember the rules for discharge of radioactive material from Austrian nuclear research installations: There were well defined limits for monthly discharges, but they could be exceeded occasionally by a factor of ten - provided that at a yearly average the limits were not exceeded. A great idea; believe it or not, this regulation originates from the sixties!



Another example is the question of radon in air at working places. Some countries in the European Union have set strict limits without referring to the time of exposure. My draft for the Austrian ordinance is close to the German regulations, where the radon exposure is limited to a value of an average concentration multiplied with the exposure time.



Having worked so long for a government I know, that much of regulations and legislation might not be the best available, but, believe me, not everything is rubbish and nonsense!!!



Best regards,



Franz













-----Ursprüngliche Nachricht-----

Von: ?????? ?? [mailto:brickner@zahav.net.il]

Gesendet: Samstag, 10. Juli 2004 11:22

An: 'Franz Schoenhofer'; 'John Jacobus'; radsafe@list.vanderbilt.edu

Betreff: RE: In-flight radiation doses





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





************************************************************************

You are currently subscribed to the Radsafe mailing list. To

unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu  Put the

text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,

with no subject line. You can view the Radsafe archives at

http://www.vanderbilt.edu/radsafe/