Allowable Total Residual Surface Contamination

DOE-HDBK-1106-97

Radiological Contamination Control Training

for Laboratory Research

Instructor's Guide

Allowable Total Residual Surface Contamination

(dpm/100 cm2)1/

Radionuclides 2/

Average 3/, 4/

Maximum 4/, 5/

Removable 4/, 6/

Transuranics, I-125, I-129, Ra-226,

RESERVED

Ac-227, Ra-228, Th-228, Th-230, Pa-231.

Th-Natural, Sr-90, I-126, I-131, I-133,

1,000

3,000

200

Ra-223, Ra-224, U-232, Th-232

U-Natural, U-235, U-238, and associated

5,000

15,000

1,000

decay product, alpha emitters.

5,000

15,000

1,000

Beta-gamma emitters (radionuclides with

decay modes other than alpha emission or

spontaneous fission) except Sr-90 and

others noted above. 7/

Figure IV-1 Surface Contamination Guidelines

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 measured by an appropriate detector for background, efficiency, and

geometric factors associated with the instrumentation.

Where surface contamination by both alpha- and beta-gamma-emitting radionuclides exists, the limits established

for alpha- and beta-gamma-emitting radionuclides should apply independently.

Measurements of average contamination should not be averaged over an area of more than 1 m2. For objects of

less surface area, the average should be derived for each such object.

The average and maximum dose rates associated with surface contamination resulting from beta-gamma emitters

should not exceed 0.2 mrad/h and 1.0 mrad/h, respectively, at 1 cm.

The maximum contamination level applies to an area of not more than 100 cm2.

The amount of removable material per 100 cm2 of surface area should be determined by wiping an area of that size

with dry filter or soft absorbent paper, applying moderate pressure, and measuring the amount of radioactive material

on the wiping with an appropriate instrument of known efficiency. 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 wiping 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.

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.

F-4