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DOE-STD-1128-98
Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities
Table 4.1.Surface Radioactivity Values,(1) dpm/100 cm2
Removable 2,4
Radionuclide
Total
(Fixed + Removable)2,3
7
7
U-nat, U-235, U-238, and associated decay products
1,000
5,000
Transuranics, Ra-226, Ra-228, Th-230,
20
500
Th-228, Pa-231, Ac-227, I-125, I-129
Th-nat, Th-232, Sr-90, Ra-223, Ra-224, U-232, I-126, I-
200
1,000
131, I-133
1,000
5,000
Beta-gamma emitters (nuclides with decay modes other
than alpha emission or spontaneous fission) except Sr-90
and others noted above5
Tritium and tritiated compounds6
10,000
N/A
1
The values in this appendix, with the exception noted in footnote 5 below, apply to radioactive contamination deposited on, but
not incorporated into the interior or matrix of, the contaminated item. Where surface contamination by both alpha- and beta-
gamma-emitting nuclides exists, the limits established for alpha- and beta-gamma-emitting nuclides apply independently.
2
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.
3
The levels may be averaged over one square meter provided the maximum surface activity in any area of 100 cm2 is less than
three times the value specified. For purposes of averaging, any square meter of surface shall be considered to be above the
surface contamination value if: (1) from measurements of a representative number of sections it is determined that the average
contamination level exceeds the applicable value; or (2) it is determined that the sum of the activity of all isolated spots or
particles in any 100 cm2 area exceeds three times the applicable value.
4
The amount of removable radioactive material per 100 cm2 of surface area should be determined by swiping the area with dry
filter or soft absorbent paper, applying moderate pressure, and then assessing the amount of radioactive material on the swipe
with an appropriate instrument of known efficiency. (Note - The use of dry material may not be appropriate for tritium.) When
removable contamination on objects of surface area less than 100 cm2 is determined, the activity per unit area shall be based on
the actual area and the entire surface shall be wiped. It is not necessary to use swiping techniques to measure removable
contamination levels if direct scan surveys indicate that the total residual surface contamination levels are within the limits for
removable contamination.
5
This category of radionuclides includes mixed fission products, including the Sr-90 which is present in them. It does not apply
to Sr-90 which has been separated from the other fission products or mixtures where the Sr-90 has been enriched.
6
Tritium contamination may diffuse into the volume or matrix of materials. Evaluation of surface contamination shall consider
the extent to which such contamination may migrate to the surface in order to ensure the surface contamination value provided in
this appendix is not exceeded. Once this contamination migrates to the surface, it may be removable, not fixed; therefore, a
"Total" value does not apply.
7
(alpha)
4.1.4 Uncertainties and Limitations
Because plutonium is relatively difficult to detect and quantify, it is important to consider
the uncertainty in the measurements when designing a plutonium monitoring program.
Although the design objective of the facility will likely be no airborne plutonium
contamination, the reality will be a measurement that ensures airborne plutonium is below
an acceptable lower limit of detection. The sampling and monitoring program will need to
4-3


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