Appendix D: Contamination and Surface Activity Thresholds

DOE-HDBK-1129-99

APPENDIX D: CONTAMINATION AND SURFACE

ACTIVITY THRESHOLDS

D.1 Appendix D to Part 835 - Surface Radioactivity Values

The data presented in Appendix D are to be used in identifying contamination and high

contamination areas as defined in Sec. 835.2(a), identifying the need for surface contamination

monitoring and control in accordance with Sec. 835.404, identifying the need for radioactive

material controls in accordance with Sec. 835.1101.

Surface Radioactivity Values {1}

[In dpm/100 cm2]

Total (fixed +

Radionuclide

Removable

removable) {2},

{2}, {4}

{3}

U-nat, U-235, U-238, and associated decay products

1,000

5,000

Transuranics, Ra-226, Ra-228, Th-230, Th-228, Pa-231, Ac-

500

227, I-125, I-129

Th-nat, Th-232, Sr-90, Ra-223, Ra-224, U-232, I-126, I-131,

200

1,000

I-133

Beta-gamma emitters (nuclides with decay modes other than

1,000

5,000

alpha emission or spontaneous fission) except Sr-90 and

others noted above {5}

Tritium and tritiated compounds {6}

10,000

N/A

{1} The values in this Appendix, with the exception noted in footnote 6, apply to radioactive contamination deposited

on, but not incorporated into the interior 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 should be

considered to be above the surface radioactivity 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 should be based on the actual area, and the entire surface should 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

should consider the extent to which such contamination may migrate to the surface in order to ensure the surface

radioactivity 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.

D-1