Area Monitoring - doe-hdbk-1184-2004

DOE-HDBK-1184-2004

the tritium decays that have escaped detection and accurate quantification due to

the physical characteristics of the STC.

The corrections needed for conversion from observed to actual STC activity

typically include the following:

A correction to increase the observed activity to account for the number of

tritium disintegrations that have escaped detection due to shielding effects of

the host particle;

A correction to reduce the observed activity to account for detected events

resulting from bremsstrahlung radiation created by tritium beta interactions with

the host particles;

A correction to reduce the observed activity to account for detected events

resulting from tritium that is present in non-STC form.

Application of these corrections will require knowledge of, or conservative

assumptions regarding, the host particle characteristics, including atomic number,

size, and density. However, using currently available technology, it is difficult to

determine the actual activity in a manner that will make it a better indicator of the

hazard to a worker than observed activity.

3.2 Area Monitoring

Because tritium emits only low energy beta particles, it is not considered an external

radiation exposure hazard. Therefore, area monitoring efforts are restricted to surface

contamination monitoring and airborne radioactivity monitoring.

Tritiated metals, metal oxides, dust, and oil can occur in nearly any tritium area. Any tritium

contamination collected on a swipe survey or a particulate filter should be viewed as a

potential combination of these. This is particularly the case for residual concentrations of

tritium, i.e., where elemental (HT), aqueous (HTO), or solvent (soluble OBT) tritium sources

have been removed or evaporated. However, it is the insoluble tritiated particulates with

very long biological retention times (i.e. ICRP Type S or M) that pose the greatest hazard

to workers. As a result, workplace sampling/monitoring programs that can quantify

specific, and distinguish between various types of STCs, will allow one to depart from the

conservative approaches recommended in this handbook.

3.2.1

Surface Contamination Monitoring

DOE - G 441.1-10, Contamination Monitoring and Control Guide (DOE 1999d),

establishes appropriate guidance for developing and implementing a surface

contamination monitoring program. This Guide addresses such issues as

monitoring requirements, techniques, frequencies, and actions. This guidance is

generally applicable to monitoring for STC contamination; however, the sample

analysis and activity determination techniques may be different due to the

difficulties in accurately assessing STC levels. Note that if the host material of the

STC is radioactive, the conventional methods in the DOE guidance can be used to

assess the extent and level of surface contamination.