Tritium Recovery

DOE-HDBK-6004-99

Tritium Recovery

The recovery function recovers the small amounts of tritium that invariably escape from the primary

confinement during operations and maintenance. Recovery involves removing tritium and any

deuterium or protium isotopes from the secondary confinement volume and holding the isotopes for

subsequent processing in the purification function. The recovery process can use zeolite beds or

metal hydride beds.

A primary recovery system operates continuously, and recovers tritium from small leaks

occurring during normal operation.

A secondary recovery operates on demand and provides a greater tritium recovery capacity

necessary for large leaks or maintenance operations.

A purge recovery system maintains the secondary confinement at a subatmospheric pressure by

exhausting continuously some of the secondary confinement atmosphere to the environment.

The purge system recovers tritium from these exhaust flows.

Tritium Purification

The purification function removes the hydrogen isotopes protium, deuterium and tritium from other

gases and then separates the tritium isotopes from protium and deuterium. The purification process

can use thermal diffusion columns or cryogenic distillation or a chromatographic process or

(preferred) a thermal cycling absorption process. The thermal cycling absorption process uses a

palladium-coated kieselguhr2 hydride bed which, upon temperature cycling, separates tritium from

protium and deuterium.

System Cleaning

The cleaning function operates on demand and cleans impurities (suspended solids, oils, moisture,

halides, etc.) from the tritium systems. Cleaning uses various detergents, chlorinated fluorocarbons,

solvents and water, followed by vacuum drying to <10-2 torr. Removal of impurities is important to

prevent stress corrosion cracking of stainless steel and contamination of the fusion machine' vacuum

vessel.

Potential System Safety Functions

The potential safety functions for the tritium systems are:

Normal Operation:

1. Provide for primary and secondary confinement barriers that separate tritium from onsite and

offsite personnel and the environment. If the safety analysis requires tertiary or higher levels of

confinement, the tritium systems should provide the additional barriers. This safety function

includes the structures, systems and components necessary to establish the barriers and the power

sources necessary to maintain the barrier operation within prescribed safety limits.

loose or porous diatomite