Measurements for transportation of tritium signs

["Pickett, Bruce D" <Bruce.Pickett@PSS.Boeing.com>]

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"

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