Re: Dirty Bomb Rescue Worker

[Ted de Castro <tdc@XRAYTED.COM>]

Good advice!  However I'd disagree on only one point ... I'd want the

GM.  The "saturation" of the GM circuitry is a thing of the distant past

that seems to survive only in the lore of our profession.  That has been

solved by correct current limiting in the circuit.  For emergency

situations I feel the KISS principle is paramount and "close enough is

good enough" for field measurement.  IC's are finicky, fussy, delicate

and complex instruments.  Gm's are simple, compact, reliable and

robust.  I like the small ones for general use and am willing to give up

the high sensitivity of large tubes in an emergency situation where low

fields (you said 2 mR/hr) don't really matter.  I like the large dynamic

range of dual tube designs like the ANPDR 27 - but save that for use

"afterwards".  Time to Discharge also greatly increases the dynamic

range of a GM - but violates KISS (almost as much as an IC) - and so I

would leave that to "afterwards" as well.





John Andrews wrote:

> 

> rob.w.powell@exxonmobil.com wrote:

> 

> >During the last 2 years of discussions about dirty bomb response, did

> >anyone see/develop a maximum exposure limit for a rescue worker?  For

> >instance, a bomber explodes the bomb but the gamma source just becomes

> >unshielded, it doesn't disperse to any extent.  An injured, immobile,

> >bleeding employee is in the 'hot zone' near the source, and a rescue worker

> >arrives with a Geiger counter.  As he/she approaches the employee while

> >reading the Geiger counter, at what reading (exposure rate) should the

> >rescue worker stop after determining that his/her risk of death during the

> >rescue is as great as that of the bleeding employee's death?  We've been

> >assuming that the rescue worker takes 15 minutes to remove the employee

> >from the hot zone (< 2 mR/hr).  This all may seem too dispassionate, but we

> >have guidance about rescuing employees who have been electrically shocked,

> >been overcome with gases, etc.

> >

> >

> >

> >-Rob Powell

> >ExxonMobil

> >Safety, Health, & Environment

> >

> >

> Rob, here is my common sense approach:

> 

> 1.  Don't use a GM unless it won't saturate and is designed for higher

> exposure rates.  Use an ion chamber type instrument.  As an emergency

> worker, I would wish I had a Rad-Tad (Eberline) or similar device to

> give me information on the shape of the field audibly.

> 

> 2.  Fifteen minutes is too long.  This is an emergency and both the

> victim and the rescuerer could die.  Not good!  Never kill the rescuerer

> trying to save the victim.  Either drag the victim away from the source

> quickly as you would drag an injured person off the highway in the face

> of oncoming traffic, or use a long (even short) stick to move the source

> away as far a possible.  I would kick it away because that would move it

> faster and farther.

> 

> 3.  Less than 2 mR/hr is a pretty low dose rate and not necessary to

> save the victim additional exposure.  Consider that the victim will be

> moved within less than one hour, then moving him or her to less than 5

> R/hr would be just as good and may save substantial trauma for a

> physically injured person.

> 

> 4.  75 R will make you feel bad for a few days, but should not kill

> anyone in normal good health and with prompt medical attention.  Given

> that, 25 R makes sense because it gives a 3X upperbound that will not be

> fatal.

> 

> 5.  Finally, most laymen can understand kicking the source out of the

> way and dragging the victim to a more sheltered location.  Do that, then

> worry about the dose.

> 

> Best seasonal wishes to all.

> 

> John Andrews

> Knoxville, Tennessee

> 

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