Radiological Control and Protection Practices

Tritium Primer

DOE-HDBK-1079-94

RADIOLOGICAL CONTROL

RADIOLOGICAL CONTROL AND PROTECTION PRACTICES

Airborne Tritium

Tritium released to room air moves readily with normal air current. The room or building

ventilation system should be designed to prevent the air from being carried to uncontaminated

areas, such as offices or other laboratories where tritium is not allowed. For that reason,

differential pressure zoning is commonly used, and released tritium is directed outside through

the building stack. In some newer facilities where the large quantities of tritium are being

handled, room air cleanup systems are available for emergency use. Following a significant

release, the room ventilation system is effectively shut down, the room is isolated, and cleanup

of room air is begun.

Secondary Containment

The most important control for preventing a release of tritium to the room atmosphere

is the use of containment around the source of tritium. This containment usually takes

the form of a glove box, which is then a secondary containment if the tritium is already

contained within the process plumbing, which is the primary containment. Even if the

tritium is on the outside surface of a piece of equipment and located inside the glove box,

through popular usage, the box is still referred to as the secondary containment.

Glove boxes used for tritium work typically are made of stainless steel or aluminum and

use gloves made of butyl, neoprene, or Hypalon. Windows are made of glass or Lexan.

In order to reduce the amount of tritium released to the atmosphere, glove boxes where

significant quantities of tritium are handled incorporate detritiation systems that process

the glove box atmosphere and remove the tritium. These detritiation systems, including

the room cleanup systems mentioned above, convert released HT to HTO and collect the

HTO on a molecular sieve for later recovery or burial. Newer systems use metal getters

that recover HT without resorting to oxidation. These getters, which can only be used

in certain glove box atmospheres, can be heated to release and recover the HT easily.

The atmosphere in the glove box may be air, nitrogen, argon, or helium, depending on

the type of activity in the box. Even in boxes with inert gas atmospheres, small amounts

of moisture and oxygen exist. Any release of tritium gas in the box will eventually be

converted to the oxide. As a result, the oxide will slowly diffuse through the gloves and

contaminate their outside surfaces. For that reason, personnel using glove boxes that

have had tritium releases are required to wear one or more additional pairs of disposable

gloves when working in the glove box.

Glove box monitors are used to alert personnel of a release in the box and may be used

to activate a cleanup system or to increase the rate of the cleanup process. With releases

of tritium in the box, the monitor chamber will eventually develop a memory from

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Tritium