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FW: Lantern mantles

To: "'radsafe@romulus.ehs.uiuc.edu'" <radsafe@romulus.ehs.uiuc.edu>
Subject: FW: Lantern mantles
From: "Lavera, Ron" <Ron.Lavera@nypa.gov>
Date: Tue, 22 Sep 1998 08:33:10 -0400

Title: FW: Lantern mantles

This message may not have made it out to the net. My apologies if this is a repeat message.

I've been following the discussion of the source checking of instruments
with some interest. There are a couple of key points that are relevant
to the issue :

1 ) Sources used to calibrate the instrument need to be similar in
emissions to the radiation the instrument will be used to measure in the
field.

2 ) Sources used for calibration must be characterized to national
standards.

3 ) When CALIBRATING the instrument, the range and linearity should be
checked to ensure required accuracy and function on all of the scales
allowed for use.

4 ) Check sources need not be characterized, but they should have
relatively stable and well known features.
     - Decay of check sources may need to be factored in to response
check criteria.
     - If the isotopic mix of the check source is changing due to build
in ( as may be possible from some processed, natural source material
)then your reading may change in unexpected manners.
     - The instrument should be source checked on each range that is
used. ( there are solder joints resistors etc. on range switches that
have been known to fail )

5 ) A response check is different from a source check. A response
check merely checks to see that the instrument indicates the presence of
radiation on at least one scale and is not looking for a specific value.
These type of periodic check is required for some emergency response
instruments.

I think that this is basically a summary of some of the portable
instrument standard criteria. It would seem to me that it would be very
easy to justify the use of response check of instruments with lantern
mantles. I think that a little more effort may be required if you
desire to use a lantern mantle for a check source. The biggest variable
that I see is the age related isotopic mix that may be present from
batch to batch and from vendor to vendor.

... very clearly, mine and mine alone ...

Ron LaVera
lavera.r@nypa.gov

-----Original Message-----
From: Daren Perrero [mailto:dmperrero@email.msn.com]
Sent: Monday, September 21, 1998 6:35 PM
To: Multiple recipients of list
Subject: RE: Lantern mantles

Dave, the use of the check source certainly provides a reasonable
assurance
that the meter is responding to radiation in a consistent manner, but
can
you make any assumptions regarding the instrument's linearity or
accuracy
over its range of operation from a single check point? I thought that
the
necessity of an periodic (full) calibration was done for this reason,
among
others.

Daren Perrero
dmperrero@email.msn.com
I'm with the government, I'm here to help you....

> -----Original Message-----
> From: radsafe@romulus.ehs.uiuc.edu
> [mailto:radsafe@romulus.ehs.uiuc.edu]On Behalf Of David Krueger
> Sent: Monday, September 21, 1998 12:23 PM
> To: Multiple recipients of list
> Subject: Re: Lantern mantles
>
> My response is that a check source only need to be long lived so that
its
> radioactivity is not going to change over the period that it will be
used.
> If an instrument is properly calibrated with traceable sources and its
> response to any check source (traceable or not) is documented, then
> continuing to use that source to verify that the instrument
> responds in the
> same way (gives the same reading consistantly) would appear to be all
that
> is necessary. Otherwise, Mike's suggestion basically ends up
calibrating
> the instrument every time it is used.
>
> Dave Krueger, CHP
> dkrueger@icnpharm.com
>
>
>
************************************************************************
> The RADSAFE Frequently Asked Questions list, archives and subscription
> information can be accessed at
http://www.ehs.uiuc.edu/~rad/radsafe.html
>

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html

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I've been following the discussion of the source =
checking of instruments with some interest.  There are a couple of =
key points that are relevant to the issue :

1 )  Sources used to calibrate the =
instrument need to be similar in emissions to the radiation the =
instrument will be used to measure in the field.

2 )  Sources used for calibration must be =
characterized to national standards.

3 )  When CALIBRATING the instrument, the =
range and linearity should be checked to ensure required accuracy and =
function on all of the scales allowed for use.

4 ) Check sources need not be characterized, =
but they should have relatively stable and well known features. 
      -  Decay of check =
sources may need to be factored in to =
response          &nbs=
p;   check criteria.
      -  If the isotopic mix =
of the check source is changing due to build in ( as may be possible =
from some processed, natural source material )then your reading may =
change in unexpected manners.

-  The instrument =
should be source checked on each range that is used.  ( there are =
solder joints resistors etc. on range switches that have been known to =
fail )

5 ) A response check is different from a source =
check.  A response check merely checks to see that the instrument =
indicates the presence of radiation on at least one scale and is not =
looking for a specific value.  These type of periodic check is =
required for some emergency response instruments.

I think that this is basically a summary of some of =
the portable instrument standard criteria.  It would seem to me =
that it would be very easy to justify the use of response check of =
instruments with lantern mantles.  I think that a little more =
effort may be required if you desire to use a lantern mantle for a =
check source.  The biggest variable that I see is the age related =
isotopic mix that may be present from batch to batch and from vendor to =
vendor.

...  very clearly, mine and mine alone =
...

Ron LaVera
 lavera.r@nypa.gov

-----Original Message-----
 From: Daren Perrero [<A =
HREF="3D"mailto:dmperrero@email.msn.com" =
TARGET=3D"_blank">mailto:dmperrero@email.msn.com</A>]
 Sent: Monday, September 21, 1998 6:35 PM
 To: Multiple recipients of list
 Subject: RE: Lantern mantles

Dave, the use of the check source certainly provides =
a reasonable assurance
 that the meter is responding to radiation in a =
consistent manner, but can
 you make any assumptions regarding the instrument's =
linearity or accuracy
 over its range of operation from a single check =
point?  I thought that the
 necessity of an periodic (full) calibration was done =
for this reason, among
 others.

Daren Perrero
 dmperrero@email.msn.com
 I'm with the government, I'm here to help =
you....

> -----Original Message-----
 > From: radsafe@romulus.ehs.uiuc.edu
 > [<A HREF="3D"mailto:radsafe@romulus.ehs.uiuc.edu"=
TARGET=3D"_blank">mailto:radsafe@romulus.ehs.uiuc.edu</A>]On Behalf Of =
David Krueger
 > Sent: Monday, September 21, 1998 12:23 =
PM
 > To: Multiple recipients of list
 > Subject: Re: Lantern mantles
 >
 > My response is that a check source only need to =
be long lived so that its
 > radioactivity is not going to change over the =
period that it will be used.
 > If an instrument is properly calibrated with =
traceable sources and its
 > response to any check source (traceable or not) =
is documented, then
 > continuing to use that source to verify that =
the instrument
 > responds in the
 > same way (gives the same reading consistantly) =
would appear to be all that
 > is necessary. Otherwise, Mike's suggestion =
basically ends up calibrating
 > the instrument every time it is used.
 >
 > Dave Krueger, CHP
 > dkrueger@icnpharm.com
 >
 >
 > =
************************************************************************=

 > The RADSAFE Frequently Asked Questions list, =
archives and subscription
 > information can be accessed at <A =
HREF="3D"http://www.ehs.uiuc.edu/~rad/radsafe.html" =
TARGET=3D"_blank">http://www.ehs.uiuc.edu/~rad/radsafe.html</A>
 >

***************************************************************=
*********
 The RADSAFE Frequently Asked Questions list, =
archives and subscription
 information can be accessed at <A =
HREF="3D"http://www.ehs.uiuc.edu/~rad/radsafe.html" =
TARGET=3D"_blank">http://www.ehs.uiuc.edu/~rad/radsafe.html</A>

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************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html

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