Re: LNT and resources [Was: Scientific responsibility]

["High Plains Drifter" <magna1@jps.net>]

Et al, just think what is could possibly do for D&D and license termination.

Alone this could possibly result in hundreds of millions of dollars put to

better use.



Dean Chaney, CHP



----- Original Message -----

From: "Gary Isenhower" <garyi@trinityphysics.com>

To: <radsafe@list.vanderbilt.edu>

Sent: Friday, June 20, 2003 8:20 AM

Subject: Re: LNT and resources [Was: Scientific responsibility]





> I can give an example of the difference LNT is making for shielding

> PET imaging centers.  Consider an uptake room with office space on

> the floor above at a distance of 12'.  Shielding in the ceiling for this

> area for various dose limits gives you the following lead thicknesses:

>

> 500 mrem/yr 8 lbs/sf

> 100 mrem/yr 40 lbs/sf

> 25 mrem/yr 60 lbs/sf

>

> These numbers ignore shielding required for the dose due to the

> adjacent uptake room and the scanner itself, so this is an

> underestimate.  For most buildings the typical structure of the ceiling

> does not do much to reduce the dose from PET sources.  NCRP says

> we OUGHT to be using 25 mrem/year, and that is the logical result of

> assuming LNT and ALARA.

>

> So, what is the cost?  If we follow the NCRP recommendations, then

> this valuable imaging modality is going to be both hard to get and

> extremely expensive, because you can't put that much lead in the the

> ceiling and/or walls and/or floor of a typical building.  LNT will

certainly

> reduce the number of sites offering PET imaging and drive the cost up

> where it is available.

>

> -Gary Isenhower

>

> Date sent:      Fri, 20 Jun 2003 05:16:48 -0700 (PDT)

> From:           John Jacobus <crispy_bird@YAHOO.COM>

>

> > I have a question for the group.  Can anyone give a

> > idea how replacement of the LNT with a different

> > model, e.g., threshold at 500 mrem or 5mSv, will

> > change how business will be done in radiation

> > protection?  What practices will change?  Surveys?

> > Documentation of environmental monitoring? Staff?

> > What legislation and regulations will change?

>

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