RE: Measurements for transportation of tritium signs

["Greger, Robert (DHS-RHB)" <RGreger@dhs.ca.gov>]

Bruce, 
This is a response to your question that I prepared for a similar inquiry a
few months ago.


I had a conversation with Wendall Carriker of DOT on this general issue a
while back.  He stated that measurements do not necessarily have to be taken
to demonstrate compliance with the contamination criteria in DOT regs.  I
prepared some guidance for our inspectors on this matter, as noted below.
 
Required Surveys Before Shipping Radioactive Material:
NRC regulations are very clear concerning the requirements for surveys of
transportation packages upon receipt(10CFR20.1906).  DOT regulations are not
as clear concerning the requirements for surveys of transportation packages
before shipment to demonstrate compliance with contamination (49CFR173.443)
and direct radiation (49CFR173.441) requirements.  According to Wendall
Carriker of DOT, it is not necessary to perform physical surveys if the
shipper can demonstrate compliance in some other manner.  DOT allows
reasonable evaluations to determine compliance with its preshipment
radiation and contamination requirements in lieu of physical surveys.  For
instance, if a sealed source is being shipped and license leak test
requirements have been met, it is not necessary to perform physical
contamination surveys to demonstrate compliance with 49CFR173.443.
Similarly, if a device containing a source that has known low radiation
levels and little potential for an increase of those levels, such as an
x-ray fluorescence device, is shipped, a physical radiation survey is not
necessary to demonstrate compliance with 49CFR173.441.  According to
Wendall, reasonableness should be applied such that physical surveys are not
needed when there is not a reasonable likelihood that radiation or
contamination levels approaching the shipping criteria could exist.
 
Rob Greger
California Radiologic Health Branch

-----Original Message-----
From: Pickett, Bruce D [mailto:Bruce.Pickett@PSS.Boeing.com]
Sent: Thursday, March 16, 2000 4:29 PM
To: Multiple recipients of list
Subject: Measurements for transportation of tritium signs


With regards to radioluminous exit signs containing tritium, how do others
on RADSAFE go about complying with the requirements of 49 CFR 173.443(a) for
package contamination surveys, and §§173.421(a)(2) & 173.424(e) for surface
radiation levels from excepted packages? Does anyone rely upon alternative
methods of assessment in lieu of wipe tests and dose rate measurements? If
so, what methods do you use or suggest?

49 CFR 173.443(a) - "The level of non-fixed (removable) radioactive
contamination on the external surfaces of each package offered for transport
must be kept as low as reasonably achievable. The level of non-fixed
radioactive contamination may not exceed the limits set forth in Table 11
and must be determined by either:
(1) Wiping an area of 300 square centimeters of the surface concerned with
an absorbent material, using moderate pressure, and measuring the activity
on the wiping material. Sufficient measurements must be taken in the most
appropriate locations to yield a representative assessment of the non-fixed
contamination levels. The amount of radioactivity measured on any single
wiping material, when averaged over the surface wiped, may not exceed the
limits set forth in Table 11 at any time during transport; or
(2) Using other methods of assessment of equal or greater efficiency, in
which case the efficiency of the method used must be taken into account and
the non-fixed contamination on the external surfaces of the package may not
exceed ten times the limits set forth in Table 11, as follows:"

49 CFR 173.421(a)(2) & 173.424(e) - "The radiation level at any point on the
external surface of the package does not exceed 0.005 mSv/hour (0.5
mrem/hour)"

Thanks,

Bruce Pickett
Seattle, WA
bruce.d.pickett@boeing.com
    "We are all ignorant. 
      Its just that each of us doesn't know different things"

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