Confinement Ventilation Systems cont'd

DOE-HDBK-1132-99

center should be considered. The inlet should have a temperature

sensor with a readout on the facility control center monitor screen.

Where spaces, such as a control room, are to be occupied during

abnormal events, filtration systems on the air inlets should be considered

to protect the occupants. Control rooms should also be protected from

the entry of smoke or other toxic gases through ventilation air intakes.

Compressed (bottled) air storage could be used to pressurize the control

room if toxic gases are present at the air intake. Alternatively, two

intakes, separately located, could lessen the likelihood of toxic gas

intake.

Either HEPA filtration or fail-safe backflow prevention for process area

intake ventilation systems should be provided.

Consideration should be given to specify cadmium-free HEPA filters to

avoid generating mixed waste.

Roughing filters or prefilters upstream of a HEPA filter should be

considered to maximize the useful life of the HEPA filter and to reduce

radioactive waste volume.

When ducts with fire dampers penetrate the secondary confinement,

boots may be needed for the clearance between the structure and the

damper sleeve.

Hot cell exhaust systems considerations are as follows:

Exhaust prefilters and HEPA filters should be installed to facilitate filter

replacement and repair. Use of a bag-in/out type filter house can lessen

personnel exposures.

Standby filters should be considered to provide backup protection and

facilitate primary filter replacement without shutting down the exhaust

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