Re: irradiated mail

[William V Lipton <liptonw@DTEENERGY.COM>]

I agree that we need an expert answer.  However, I doubt that the

electron beam used would produce most of the dose near the surface, since

the LET of electrons increases as they lose energy.  Since the energy

used would have to be high enough for the electrons to completely penetrate

the item being irradiated,  the dose may actually increase with depth.

The opinions expressed are strictly mine.
It's not about dose, it's about trust.
Curies forever.

Bill Lipton
liptonw@dteenergy.com

"Franta, Jaroslav" wrote:

 

I hope an expert answers your question.
In the mean time, the common sense answer is that, in thicker pieces of mail, the gammas deposit their energy evenly throughout, whereas the e-beam will deposit it mostly near the surface.

In technical lingo, we say that the "Bragg peak" is close to the surface.

Jaro

-----Original Message-----
From: William V Lipton [mailto:liptonw@DTEENERGY.COM]
Sent: Thursday August 29, 2002 7:17 AM
To: Muckerheide
Cc: Jim Hardeman; radsafe@list.vanderbilt.edu
Subject: Re: irradiated mail

My understanding is that virtually all of the dose from gamma irradiation is
produced by the secondary electrons.  In that case, how would gamma irradiation
produce different effects than beta or electron beam irradiation?

The opinions expressed are strictly mine.
It's not about dose, it's about trust.
Curies forever.

Bill Lipton
liptonw@dteenergy.com

Muckerheide wrote:

> Jim,
>
> As noted, e-beams, not gammas. E-beams are "politically-correct" vs.
> radioisotopes/radioactivity.
>
> Another fool's errand pushed by ignorance by "authorities" and "marketing"
> playing on anti-radiation perceptions.
>
> Regards, Jim
>
> on 8/28/02 6:00 PM, Jim Hardeman at Jim_Hardeman@dnr.state.ga.us wrote:
>
> > Ruth -
> >
> > Based on what I saw about the "irradiation machines", I think you're probably
> > looking at electron beams rather than gamma or X-rays. I would suspect the
> > reaction of electrons w/ the organic sulfides would be similar to that of
> > alphas.
> >
> > I've heard stories (that's the best I can characterize them) of the clear
> > plastic windows on irradiated envelopes being browned / charred, other
> > plastics (floppy disks, CD's, etc.) being "melted" or deformed. To my mind the
> > chemical reactions in irradiated plastics are as likely, if not more likely,
> > to be responsible for the production of "irritants" as the irradiation of
> > paper ... assuming for the sake of argument, of course, that some sort of
> > irritants are actually produced by the irradiation process.
> >
> > For what it's worth, when I was working on the Radiation Sterilizers, Inc.
> > (RSI) cleanup here in Decatur, GA seemingly a lifetime ago (it was only 1988),
> > we were working with paper products, predominantly cardboard boxes, that had
> > been sterilized with gamma doses in the megarad range ... and we handled those
> > products with no ill effects. Now granted, we were surveying them for
> > contamination, so we did have latex gloves, etc. ... so that may not be a
> > valid data point ... but in the thousands of person-hours that we worked with
> > these products, I don't recall anybody saying anything about any sort of
> > irritant.
> >
> > My $0.02 worth ...
> >
> > Jim Hardeman
> > Jim_Hardeman@dnr.state.ga.us

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