Re: Asking for opinions

[Chris Alston <alstonc@odrge.odr.georgetown.edu>]

Joe

Glass doesn't have any water in it, you know. At some energies, it's a better shield than concrete. The perception , or understanding, of that, is, of course, another matter, and has to do with social psych, and public relations, not radiological physics. But, it would seem to be only fair to assume that your CHP is competent and honest. If he/she's run the calcs, and the shielding provided by the glass (it's implied that it's the same thickness as the rest of the wall) is equivalent to that provided by the concrete, then there's nothing conceivably unethical about saying so. Getting people to believe it is a different horse. Why don't you put up some area monitors, and make some measurements? You'd have an MDQ of ten (10) mrem/quarter, if you were to use ordinary TLD badges (i.e., leave them in place for three (3) months). Leave them in situ for six (6) months, and you'd get down to five (5) mrem/quarter.

Break a leg

cja
alstonc@odrge.odr.georgetown.edu


At 02:51 PM 9/10/99 -0500, you wrote:
>A situation came up at our facility and I am interested in getting a general
>consensus as to how to interpret the issue.
>
>We had a TLD rack at the entrance to our facility where people put their
>TLDs when they leave the site. This rack is a vertical board between 3 & 6
>feet above the floor. 3 feet in front of the rack is a wall. The wall is 16
>inch thick concrete from the floor to about a height of 3 feet and glass
>from 3 to 7 feet above the floor. If you are standing at the TLD rack
>looking out, your 135 degree field of view would be obstructed by two
>concrete door jams about a foot wide each and the rest would be glass.
>
>A concern was raised that radioactive material would be routinely parked
>about 10-15 feet outside the glass and that this might dose the TLDs
>unnecessarily. Two independent assessments by Rad engineers (one a  CHP)
>concluded that between 20-40 mrem per quarter may be absorbed by the TLDs
>and that moving the rack was a reasonable precaution. This actually has some
>relevance considering the collective dose goals of the site.
>
>A management type CHP wrote up an analysis that assumed that the  mostly
>glass wall was approximated by a 16 inch thick concrete wall and he
>concluded that the TLDs would get no dose. The question I would like
>RADSAFERs to comment on is "How would you interpret a case where an HP
>approximates a mostly glass wall as a concrete wall for shielding
>calculations?". Although there is no human health issue involved, would this
>border on being or is it blantantly unethical?.  Obviously, reasonable
>people can disagree but for the purposes of this discussion, give your
>opinion based on the assumption that you could see the radioactive material
>from the TLD location and 100 or at least 99 out of 100 people would agree
>that the only thing directly between the source and the TLDs was a pane of
>glass.
>
>Thank you to all who chime in.
>Joe Archer
>
>
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