Process Monitoring

Tritium Primer

DOE-HDBK-1079-94

TRITIUM MONITORING

determine the concentration, the relative humidity must be known. Another sampling

technique is to squeeze a soft plastic bottle several times to introduce the air (containing

the HTO) into the bottle. A measured quantity of water is then introduced, and the bottle

is capped and shaken. In a minute or less, essentially all the HTO is taken up by the

water, which is then analyzed.

Other techniques involve placing a number of vials or other small specially designed

containers of water, cocktail, or other liquid in selected locations in the area being

monitored. After a period of time (usually a number of days), the liquid in the

containers is analyzed. The result is qualitative (for open containers) to semiquantitative

(for specially designed containers).

Process Monitoring

Ionization chambers are typically used for monitoring stacks, rooms, hoods, glove boxes,

and processes. The outputs can be used to sound alarms, activate ventilation valves,

activate detritiation systems, and perform other functions. In general, it can be expected

that stack, room, and hood monitors will require little nonelectronic maintenance (i.e.,

chamber replacement because of contamination). Under normal circumstances, the

chambers are constantly flushed with clean air and are not exposed to high tritium

concentrations. However, glove box monitors can be expected to eventually become

contaminated, especially if exposed to high concentrations of HTO. Process HT monitor

backgrounds can also be expected to present problems if a wide range of concentrations

(4 to 5 orders of magnitude) are to be measured.

Mass spectrometers, gas chromatographs, and calorimeters are the main instruments used

for process monitoring. Because of their relative insensitivities, these instruments cannot

detect tritium much below a few parts per million (Ci/m3). For this reason, the

analytical results and the related health physics concerns must be interpreted carefully.

It is not uncommon to find that samples showing no trace of tritium when analyzed on

a mass spectrometer may actually have a concentration of several curies of tritium per

cubic meter. In spite of their contamination problems, ionization chamber instruments

are useful for measuring these lower concentrations and for providing instant indications

of changing concentrations that are not possible with the more sophisticated instruments.

Surface Monitoring

Any material exposed to tritium or a tritiated compound has the potential of being contaminated.

Although it is difficult to quantify tritium contamination levels, several methods are available

to evaluate the extent of contamination, including smear surveys and off-gassing measurements.

Good housekeeping and work practices are essential in maintaining contamination at acceptable

levels.

For health or safety implications, an indication of loose, removable tritium contamination is

more valuable than a measurement of the total surface contamination. Loose tritium can be

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Tritium