Table 1-1 Ratio of DCF for Selected STC to DCF for Selected Radioactive Isotope or Compound

DOE-HDBK-1184-2004

The behavior of STCs can present a variety of challenges to a facility's radiation protection

program. For example:

It may be difficult to differentiate between STCs and the more common forms of tritium

using routine workplace monitoring techniques.

The physical and chemical behavior of STCs may render commonly used tritium

bioassay and available internal dose models ineffective.

Difficulties in identifying and quantifying STC contamination can cause significant

delays between performance of workplace monitoring and completion of analyses.

In the absence of effective detection methods, workplace hazards cannot be accurately

assessed. Without accurate hazard assessments, associated activities such as area

posting, material labeling, job planning, access control, and material release, are made

difficult.

The risk associated with STCs can be put into perspective by comparing the effective dose

equivalent per unit uptake (DCF) of various STCs with the effective dose equivalent per

unit uptake of other representative radionuclides. As shown in Table 1-1, the DCF for Hf-T,

a very insoluble tritiated particle is about 24 times that of HTO, while it is one twentieth that

of 137Cs, and one 270,000th that of 239Pu. Thus, while the risk associated with STC that

results in the greatest dose per unit uptake is greater that that from tritium oxide, it is less

than the risk associated from fission products and actinides. Note that when assessing the

hazard from STCs and other forms of radioactive material, it is necessary to know the

quantities of material available for uptake, as well as the opportunities for uptake in addition

to the inherent risk associated with the radioactive material.

Table 1-1 Ratio of DCF for Selected STC to DCF for Selected Radioactive

Isotope or Compound

Ratio of DCF for selected

STC to DCF for selected

STC/Isotope

radioactive isotope or

compound

H f -T

HTO

OBT

HTO

Hf -T

1/20

137

H f -T

1/77,000

235

H f -T

1/270,000

239