ACCEPTABLE SURFACE CONTAMINATION LEVELS
AVERAGE B C F
MAXIMUM B D F
REMOVABLE B E F
U-nat, U-235, U-238, and associated decay products
5,000 dpm/100 cm2
15,000 dpm/100 cm2
1,000 dpm α/100 cm2
Transuranics, Ra-226, Ra-228, Th-230, Th-228, Pa-231, Ac-227, I-125, I-129
100 dpm/100 cm2
300 dpm/100 cm2
20 dpm/100 cm2
Th-nat, Th-232, Sr-90, Ra-223, Ra-224, U-232, I-126, I-131, I-133
1000 dpm/100 cm2
3000 dpm/100 cm2
200 dpm/100 cm2
Beta-gamma emitters (nuclides with decay modes other than alpha emission or spontaneous fission) except SR-90 and others noted above
5000 dpm/100 cm2
15,000 dpm/100 cm2
1000 dpm βγ/100 cm2
Where surface contamination by both alpha- and beta-gamma-emitting nuclides exists, the limits established for alpha-and beta-gamma-emitting nuclides should apply independently.
As used in this table, 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.
Measurements of average contaminant should not be averaged over more than 1 square meter. For objects of less surface area, the average should be derived for each such object.
The maximum contamination level applies to an area of not more than 100 cm2.
The amount of removable radioactive material per 100 cm2 of surface area should 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 should be reduced proportionally and the entire surface should be wiped.
The average and maximum radiation levels associated with surface contamination resulting from beta-gamma emitters should not exceed 0.2 mrad/hr at 1 cm and 1.0 mrad/hr at 1 cm, respectively, measured through not more than 7 milligrams per square centimeter of total absorber.
[Statutory Authority: RCW 70.98.050
and 70.98.080. WSR 09-06-003, § 246-232-140, filed 2/18/09, effective 3/21/09. Statutory Authority: RCW 43.70.040
. WSR 91-02-049 (Order 121), recodified as § 246-232-140, filed 12/27/90, effective 1/31/91. Statutory Authority: RCW 70.98.080
. WSR 87-01-031 (Order 2450), § 402-19-590, filed 12/11/86; WSR 83-19-050 (Order 2026), § 402-19-590, filed 9/16/83.]