ES&H Manual

Radiation Control Supplement

 

 

 

Appendix 2B

Contamination Control Limits

 

 

 

Summary of Contamination Limits1

Nuclide

Removable2,4

(dpm/100 cm2)

Total (Fixed + Removable)2,3

(dpm/100 cm2)

 

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

1,0007

5,0007

 

Transuranics, Ra-226, Ra-228, Th-230, Th-228, Pa-231, Ac-227, I-125, I-129

20

500

 

Th-nat, Th-232, Sr-90, Ra-223, Ra-224, U-232, I-126, I-131, I-133

200

1,000

 

Beta-gamma emitters (nuclides with decay modes other than alpha emission or spontaneous fission) except Sr-90, Be-7 and others noted above.5

1,000

5,000

 

Tritium and Special Tritium Compounds (STC)6

10,000

See Note 6

 

Be-78

30,000

30,000

 

Notes:

1.      The values in this table, with the exception noted in footnote 6 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 that is present in them.  It does not apply to Sr-90 that 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 table is not exceeded.  Once this contamination migrates to the surface, it may be removable, not fixed; therefore, a “Total” value does not apply.  In certain cases, a “Total” value of 10,000 dpm/cm2 may be applicable either to metals of  the types from which insoluble special tritium compounds are formed, that have  been exposed to tritium, or to bulk materials to which insoluble tritium compound particles are fixed to a surface.

7.      These limits apply only to the alpha emitters within the respective decay series.

8.      For use when Be-7 is suspected or known to be the primary constituent in the contamination.  This limit applies to use of equipment and items in Controlled Areas only.  Items released from the Controlled Area shall meet applicable DOE requirements for release.  Locations known to have Be-7 contamination above the limits for beta-gamma emitters shall be identified and posted, marked or labeled to warn individuals not to enter without the proper radiological control authorization.  See exemption decision letter, June 8, 1998.

 

 

 

ISSUING AUTHORITY

CHAPTER AUTHOR

APPROVAL DATE

EFFECTIVE DATE

EXPIRATION DATE

REV.

 

 

 

RadCon Dept

Keith Welch

07/01/10

07/01/10

07/01/13

4

 

This document is controlled as an on line file.  It may be printed but the print copy is not a controlled document.  It is the user’s responsibility to ensure that the document is the same revision as the current on line file.  This copy was printed on 7/6/2010.