Confinement Ventilation Systems cont'd

DOE-HDBK-1132-99

vestibules may be used to minimize the impact of open doors or hatches on the

ventilation system and to prevent the spread of airborne contamination within

the facility.

Air cleanup systems provided in confinement ventilation exhaust systems are

typically used to limit the release of radioactive or other hazardous material to

the environment and to minimize the spread of contamination within the facility.

To the extent practical, discrete processing steps should be performed in

individual process confinements to reduce the amount of hazardous material

that can be released by a single or local failure of the confinement system. The

following general cleanup system features should be considered, as

appropriate, for ventilation system design:

The level of radioactive material in confinement exhaust systems should

be continuously monitored. Alarms should annunciate when activity

levels above specified limits are detected in the exhaust stream.

Appropriate manual or automatic protective features that prevent an

uncontrolled release of radioactive material to the environment or

workplace should be provided.

Elevated confinement exhaust discharge locations can limit onsite doses

and reduce offsite doses by enhancing atmospheric dispersion. An

elevated stack should be used for confinement of exhaust discharge.

Provisions should be made to provide an adequate ventilation exhaust

discharge path in the event of stack failure. The stack should be located

so that it cannot fall on the facility or an adjacent facility. Alternatively,

the stack may be constructed to remain functional following accidents,

including those caused by severe natural phenomena and man-made

external events. Stack location and height should also consider intakes

on the facility and adjacent facilities to preclude uptake.

Guidance for air sampling locations is provided in ACGIH/ASHRAE

criteria. Sample collecting devices should be located as close to the

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