§336.364. Appendix G. Acceptable Surface Contamination Levels.



Acceptable Surface Contamination Levels


Radionuclide1 Average2,3,6 Maximum2,4,6 Removable2,3,5,6
U-natural, U-235, U-238,
and associated decay
products except Ra-226,
Th-230, Ac-227, and Pa-231


Transuranics, Ra-223,
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,
and I-133


Beta-gamma emitters
(radionuclides with decay
modes other than alpha
emission or spontaneous
fission) except Sr-90
and others noted above
5,000 dpm
alpha/
100 cm2




1,000
dpm/
100 cm2





5,000 dpm
beta-
gamma/
100 cm2
15,000 dpm
alpha/
100 cm2




3,000
dpm/
100 cm2





15,000 dpm
beta-
gamma/
100 cm2
1,000 dpm alpha/
100 cm2






200 dpm/
100 cm2








1,000 dpm beta-gamma/100 cm2


1. Where surface contamination by both alpha- and beta-gamma-emitting radionuclides exists, the limits established for alpha- and beta-gamma-emitting radionuclides should be applied independently.

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 appropriate 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 objects of 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 centimeters (cm2).

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 assessing the amount of radioactive material on the wipe with an appropriate instrument of known efficiency. When removable contamination on objects of less surface area is determined, the pertinent levels shall be 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.