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Re: Another question re: dose
The determination of the whole body equivalent for organ doses is covered in 10
CFR 20, through the specified weighting factors. That's what TEDE is all
about. The 10 CFR 20 approach is based on ICRP26 and ICRP30. This is further
refined in ICRP60, et. al, although this refinement has not yet been
incorporated into U.S. regulations.
The opinions expressed are strictly mine.
It's not about dose, it's about trust.
Curies forever.
Bill Lipton
liptonw@dteenergy.com
Jack_Earley@RL.GOV wrote:
> Richard Hess wrote:
>
> <<One item caught my attention. Someone was trying to differentiate between
> a whole-body dose (let's say 10mSv/year) and that same dose applied to a
> single point (I think the example was within the lung).
>
> I realize that an alpha emitter may create a much greater risk (why else is
> its QF 20?) but I think I'm lost about whole body doses and point doses.
>
> Now that I'm thinking about it, how do some things become contaminated with
> radiation while others don't?>>
> ____________
>
> If it was the same article I read most of, they were trying to differentiate
> between whole body dose and the dose on a cellular level. Something like
> "hundreds, thousands, millions of hits on these [poor] cells over weeks,
> months, and years!" Of course, the author kind of forgot to mention that
> these same cells receive millions of hits per day from background sources. .
> . .
>
> On whole body vs. point sources, though, it's still a matter of dose--the
> difference is the insult to the organism vs. the organ. For example, if you
> burn 90 percent of your hand, you'll survive although you may lose your
> hand. If you burn 90 percent of your body, your survival chances shrink.
> Depends on the dose, though--were those 1st, 2nd, or 3rd degree burns? High
> doses are used to kill tumors--if applied to the body as a whole, you would
> die from it. Same thing if you kill the wrong organ--you can be stabbed in
> the stomach and survive, but unlikely if you're stabbed in the heart.
>
> Radiation can't contaminate anything. Big media misunderstanding on the
> concept here--I cringe anytime I hear a media report on radiation because I
> know what's coming: "There was no leak of radiation." Radiation is energy;
> if it "leaks," it's because there was an inadequate shield, e.g., only 1 in.
> of shielding at one location instead of the 5 in. everywhere else. You can't
> become contaminated from energy. Some things can be radioactive by being
> activated from, e.g., neutron irradiation. In that case, the material would
> absorb a neutron, changing its chemical form, such as from H-2 to H-3, and
> since it now has more energy, it has to decay to a stable state. A general
> definition of contamination is radioactive material somewhere you don't want
> it to be. Fertilizer in your yard or stable is fine--not so good on your new
> carpet. We don't consider a sealed source to be contaminated unless it leaks
> to the outside. From there it can spread to anything with which it comes in
> contact. It can fall off during transport and contaminate whatever it lands
> on. The question then becomes, how much? We had a man injured inside the
> reactor building at TMI some years ago. Checking the transport path after he
> was taken to the ambulance, the area that was contaminated was where the
> stretcher was placed, even though it had been covered with plastic before
> the man was placed in it. But it had been on top of an emergency response
> cabinet for years, and although the minute quantities of radioactive
> material that landed on it from the air were all immeasurable, and well
> below any limits, they built up over time to become measurable and above
> limits, and therefore "contamination."
>
> Jack Earley
> Radiological Engineer
>
> -----Original Message-----
> From: Richard L. Hess [mailto:lists@richardhess.com]
> Sent: Friday, September 06, 2002 2:35 PM
> To: radsafe@list.vanderbilt.edu
> Subject: Another question re: dose
>
> A while ago someone posted an anti-nuke URL to this list. I went and read
> it and started seeing through all of the hoopla.
>
> One item caught my attention. Someone was trying to differentiate between a
> whole-body dose (let's say 10mSv/year) and that same dose applied to a
> single point (I think the example was within the lung).
>
> I realize that an alpha emitter may create a much greater risk (why else is
> its QF 20?) but I think I'm lost about whole body doses and point doses.
>
> Now that I'm thinking about it, how do some things become contaminated with
> radiation while others don't?
>
> Pointers to GOOD FAQs would be useful (it's hard to separate wheat from
> chaff in this subject on the Web).
>
> A little math doesn't scare me...but lots of math does <smile>.
>
> Thanks!
>
> Richard
>
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