§336.364. Appendix G. Acceptable Surface Contamination Levels.
|U-natural, U-235, U-238,
and associated decay
products except Ra-226,
Th-230, Ac-227, and Pa-231
Ra-224, Ra-226, Ra-228
Th-natural, Th-228, Th-230,
Th-232, U-232, Pa-231,
Ac-227, Sr-90, I-125,
I-126, I-129, I-131,
(radionuclides with decay
modes other than alpha
emission or spontaneous
fission) except Sr-90
and others noted above
1,000 dpm alpha/
1,000 dpm beta-gamma/100 cm2
1. Where surface contamination by both alpha- and beta-gamma-emitting radionuclides
limits established for alpha- and beta-gamma-emitting radionuclides should be applied
2. As used in this appendix, dpm (disintegrations per minute) means the rate of emission by
radioactive material as determined by correcting the counts per minute observed by an
detector for background, efficiency, and geometric factors associated with the instrumentation.
3. Average contamination level shall not be measured over more than 1 square meter. For
less surface area, the average shall be derived for each object.
4. The maximum contamination level applies to an area of not more than 100 square
5. The amount of removable radioactive material per 100 cm2 of surface area
shall be determined by
wiping that area with dry filter or soft absorbent paper, applying moderate pressure, and
amount of radioactive material on the wipe with an appropriate instrument of known efficiency.
removable contamination on objects of less surface area is determined, the pertinent levels shall
reduced proportionally and the entire surface shall be wiped.
6. The average and maximum radiation levels associated with surface contamination resulting from beta-gamma emitters shall not exceed 0.2 millirad/hour at 1 cm and 1.0 millirad/hour at 1 cm, respectively, measured through not more than 7 milligrams/cm2 of total absorber.