RE: Swab Conversions -Reply

[Harvey Farr <farrhc@myapc.com>]

The NRC has provided the following guidance for determining efficiency
of various types of smear media (e.g., paper vs cloth) in order to
determine compliance with 10CFR71 and DOT limits for removable
contamination on packages.  Seems to me the same approach can be
used for determining the efficiency of a swab.  See NRC I.E. Information
Notice 85-46,CLARIFICATION OF SEVERAL ASPECTS OF REMOVABLE
RADIOACTIVE SURFACE CONTAMINATION LIMITS FOR TRANSPORT
PACKAGES

"An acceptable method of demonstrating wipe (smear) efficiency is
repetitive wiping of a portion of the package surface. The demonstrated
wipe efficiency is the ratio of the initial smear activity to the summation of
activity on all  the wipes of the designated portion of the package
surface. For the purpose of  this calculation, one can assume all
activity is removed when two consecutive wipes show less than 10%
of the activity of the initial wipe. Because of variations in package
surfaces and contamination characteristics, care should  be taken to
ensure that the demonstrated wipe efficiency is representative of
the wipes to which it is applied. This will normally require delaying
package decontamination until after conduct of wipe efficiency
determinations if an  efficiency greater than 10% is used."