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RE: Decay in Storage
You should also keep in mind the labeling may not reflect other impurities
that may be present. These impurities may represent a trivial dose compared
to the labeled product, but enough long-lived material may be present to
keep the it well above background. An example that comes to mind is Fe-59
citrate-there will invariably be Co-60 present also. I ran across a bottle
labeled Ag-110m (approx. 250 day half-life) dated from the early seventies
that was well above background due to the presence of Ag-108m (half-life
approx. 127 y).
And lets not forget a previous discussion on Sm-153-also present probably
was Sm-144 with neutron activation leading to Sm-145 with a half-life of
340 days along with Eu isotopes probably due to the presence of all the
other naturally abundant isotopes of Sm, esp. Sm-154: Neutron activation
leads to Sm-155 which in turn results in Eu-155 (half-life approx. 1.8 y).
DJWhitfill
Opinions expressed are mine and do not reflect official policies or
positions of the Kansas Department of Health and Environment.
"Radiological
Health Unit" To: Multiple recipients of list
<raldrich@nysnet.n <radsafe@romulus.ehs.uiuc.edu>
et> cc:
Sent by: Subject: RE: Decay in Storage
radsafe@romulus.eh
s.uiuc.edu
04/19/00 01:12 PM
Please respond to
radsafe
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The purpose for the DIS rules is to cut a break for licensees so that =
they do not have to send their short-lived waste to a licensed disposal =
facility. Its a way around the inescapable fact that there is not and =
will likely never be a de minimus or BRC rule. (And this is the thanks =
we get!)
The requirement for both 10 half-lives decay and a survey showing it is =
indistinguishable from background becomes more reasonable when you =
consider the licensees for which DIS is an option: mostly small medical =
and research facilities. Generally these licensees are unsophisticated =
in health physics. Most are pretty small operations with RSOs who are =
not HPs and whose primary responsibility is not managing the radiation =
control program.=20
By requiring that both criteria be met, regulators have a little more =
confidence that the facility's cold trash won't be setting off alarm =
bells down stream.=20
************************************************************************
Clayton Bradt, CHP <raldrich@nysnet.net> phone: 518/457-1202
Assoc. Radiophysicist fax: =
518/485-7406
NYS Dept. of Labor
Radiological Health Unit
Blg.12, Rm 169
State Office Campus
Albany, NY 12240
***********************************************************************
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<HTML><HEAD>
<META content=3D"text/html; charset=3Diso-8859-1" =
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<STYLE></STYLE>
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<DIV><FONT face=3D"Courier New" size=3D2>The purpose for the DIS rules =
is to cut a=20
break for licensees so that they do not have to send their =
short-lived=20
waste to a licensed disposal facility. Its a way around the inescapable =
fact=20
that there is not and will likely never be a de minimus or BRC rule. =
(And this=20
is the thanks we get!)</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3D"Courier New" size=3D2>The requirement for both 10 =
half-lives=20
decay and a survey showing it is indistinguishable from background =
becomes more=20
reasonable when you consider the licensees for which DIS is an option: =
mostly=20
small medical and research facilities. Generally these licensees =
are =20
unsophisticated in health physics. Most are pretty small operations with =
RSOs=20
who are not HPs and whose primary responsibility is not managing the =
radiation=20
control program. </FONT></DIV>
<DIV><FONT face=3D"Courier New" size=3D2>By requiring that both criteria =
be met,=20
regulators have a little more confidence that the facility's cold =
trash=20
won't be setting off alarm bells down stream.</FONT> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV><FONT face=3D"Courier New"=20
size=3D2>****************************************************************=
********<BR>Clayton=20
Bradt, CHP <<A=20
href=3D"mailto:raldrich@nysnet.net";>raldrich@nysnet.net</A>> &nbs=
p; =20
phone: 518/457-1202<BR>Assoc.=20
Radiophysicist  =
; =
&=
nbsp; =20
fax: 518/485-7406<BR>NYS Dept. of=20
Labor<BR>Radiological Health Unit<BR>Blg.12, Rm 169<BR>State Office=20
Campus<BR>Albany, NY=20
12240<BR>****************************************************************=
*******</FONT></DIV></BODY></HTML>------=_NextPart_000_0046_01BFAA08.CA7838C0--
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