Renovable Contamination

DOE-HDBK-1184-2004

3.2.1.1 Removable Contamination

The first step in establishing a surface contamination monitoring program for STCs

is to identify the likelihood that STCs may exist in an area, and if they do, identify

the most likely locations. The best sources of this type of information are historical

records and workers' memories of facility usage. Facility management should

consult these sources for information regarding previous usage of the facility and

specific areas. Almost any area in which tritium was used, handled, or stored may

be considered a candidate for possible STC contamination. For larger facilities,

identification of all STC contaminated areas may be quite time-consuming. Priority

should be placed on identifying and controlling those areas that are likely to have

the highest STC contamination levels. In many cases, this will include areas where

STCs were intentionally created, and areas that have (or had) the highest tritium

contamination levels and the highest probability of host particle formation and

distribution. Such a determination should be made by review of historical

radiological monitoring records and facility processes.

Following identification of those areas most likely to be contaminated with STCs,

detailed radiological monitoring should be performed to identify tritium

contamination levels in the area(s). Such monitoring should be performed using

routine tritium contamination monitoring techniques, commonly using either wet or

dry smears and liquid scintillation counting (LSC). In the past, many facilities have

used styrofoam smears for collection of surface contamination samples for tritium

analyses. Recent changes in the composition of scintillation cocktail fluid have

largely eliminated this practice. The actual sample medium used is not particularly

significant as long as its efficacy in collection of particulate material and suitability

for LSC analysis can be demonstrated. Counting techniques should be capable of

detecting contamination at or below the values provided in Appendix D of 10 CFR

Part 835.

If the results of comprehensive smear surveys indicate that tritium surface

contamination levels are less than one tenth of the 10 CFR 835 Appendix D value,

then it may be appropriate to assume that there are no significant levels of STC

contamination (i.e., levels requiring additional controls, such as posting, access

control, or personnel monitoring). If the results of the smear surveys indicate that

tritium contamination levels equal or exceed one tenth of the 10 CFR 835 Appendix

D values, then further surveys may be conducted to identify sources of STCs in the

area. It may also be necessary to identify the host material(s) so that appropriate

assumptions may be made regarding assimilation and elimination.

3.2.1.2 Total Contamination

DOE has not established a total (fixed pus removable) surface contamination value

for tritium and tritium compounds. The reason is that tritium can diffuse into the

volume of any material to which it is exposed at least in the gaseous forms

normally encountered. After the exposure, the tritium migrates to the surface,

making a definitive distinction between fixed and removable contamination difficult

to ascertain.