Release Limit Requirements for Surface-Contaminated Material

DOE-HDBK-1129-99

8.1.1 Release Limit Requirements for Surface-Contaminated Material

There are two DOE directives: Federal Rule 10 CFR 835, "Occupational Radiation Protection," and

DOE Order 5400.5, which cover the control limits and methods of removable surface

contamination measurement.

Appendix D of 10 CFR 835 specifies surface contamination value for use in determining whether a

location needs to be posted as a contamination or high-contamination area (Subpart G), and if an

item is considered to be contaminated and cannot be released from a contamination or high-

contamination area to a controlled area (Subpart L). 10 CFR 835 does not permit unrestricted

release of contaminated items. The surface contamination value for removable tritium is 10,000

dpm/100 cm. In addition, Footnote 6 of Appendix D provides a requirement to consider the

migration of tritium from the interior of an item to the surface when applying the surface

contamination value for tritium.

The second regulation concerns the release of materials per the requirements of DOE Order

5400.5. This document provides requirements for unrestricted release of contaminated objects.

This requirement is described in the document "Response to Questions and Clarification of

Requirements and Processes: DOE 5400.5, Section II.5 and Chapter IV Implementation

(Requirements Relating to Residual Radioactive Materials)." [34] This document recommends the

use of 10,000 dpm/100 cm2 as an interim guideline for removable tritium. This limit is also

specified in Table 1, "Surface Activity Guidelines." (See Appendix D.)

The committee drafting ANSI standard N13.12, "Surface and Volume Radioactivity Standards for

Clearance," during a presentation at the 1998 annual meeting of the Health Physics Society,

reported that the proposed screening level for unrestricted used items with residual levels of tritium

on the surface was 600,000 dpm/100 cm, of which no more than 20% or 120,000 dpm/100 cm

should be removable. This recommendation has not yet been approved for publication by ANSI.

Although not specifically addressed in the regulations, users should be cautioned that, in some

cases, the initial, relatively clean concrete surface measurements did not accurately characterize

the bulk tritium contents (see 4.6.2).

8.1.2 Removable Surface Contamination Measurement Process

The regulatory requirements are not specific as to how the removable surface contamination wipe

is to be done or whether or not it is to be wet or dry. Footnote 4 of Appendix D to 10 CFR 835

states that a dry wipe may not be appropriate for tritium, but does not provide an explanation as to

what may be appropriate. As a result, it would seem that either a wet or dry wipe can be used and

still meet the requirements of 10 CFR 835. The requirements stated in "Response to Questions

and Clarification of Requirements and Processes" [34] include: "The measurement should be

conducted by a standard smear measurement but using a wet swipe or piece of Styrofoam,"

although in Table 1 of this document, a dry wipe (i.e., a dry filter or soft absorbent paper) is

specified. The "should" included in this sentence and the use of Styrofoam would seem to allow

for the use of either dry or wet wipes.

The use of a wet or dry wipe to determine removable surface contamination levels is noteworthy

due to possible differences in measured levels between the two techniques.