Ventilation Control - hdbk110697

DOE-HDBK-1106-97

Ventilation Control

Airflow

Airflow should be from the areas of least contamination to areas of most

contamination (e.g., clean to contaminated to highly contaminated areas) such as

fume hoods, gloveboxes, etc.

Pressure differential

Slight negative pressure is maintained in buildings/rooms where potential

contamination exists.

High Efficiency Particulate Air (HEPA) filtration.

HEPA filters, which remove radioactive particles from the air, may be used. This is

commonly required for higher levels of airborne radioactivity such as concentrations

exceeding 10 percent of the Derived Air Concentration (DAC) for a particular

radionuclide. Charcoal filters are required for specific radionuclides such as iodine.

Ventilation system requirements should be determined in consultation with the

Radiological Control Organization.

A DAC is the radionuclide airborne concentration. Breathing an air concentration of

1 DAC for 1 working year (2,000 hours) will result in committed dose equivalent

equal to an annual limit, i.e., 5 rem whole-body or 50 rem to any organ or tissue.

Flow rate

Always check the flow rate or pressure in ventilated enclosures before starting

operations. Air flow is easily measured with an inexpensive velometer. Refer to

facility-specific flow rate measurement requirements.