Turbulent Airflow Patterns in Nuclear Workplace - Computer Simulation and Qualitative Tests

Concentration of airborne radioactive materials inside a room can vary widely from one location to another, sometimes by orders of magnitude even for locations that are relatively close. Inappropriately placed samplers can give misleading results and, therefore, the location of air samplers is important. Proper placement of samplers cannot be determined simply by observing the position of room air supply and exhaust vents. Gas-aerosol flow patterns should be analyzed theoretically (numerical simulations) and experimentally, such as the release of smoke aerosols. The significance of air and aerosol flow pattern studies depends on the purpose of sampling - for estimating worker intakes, warning of high concentrations, defining airborne radioactive areas, testing for confinement of sealed radioactive materials, etc. When sampling air in rooms with complex airflow patterns, it may be useful to use qualitative airflow studies with smoke tubes, smoke candles or isostatic bubbles. The U.S. Nuclear Regulatory Commission - Regulatory Guide 8.25', suggests that an airflow study should be conducted after any changes at work area, including changes in the setup of work areas, ventilation system changes, etc. The present work presents a turbulent gas-aerosol flow patterns study conducted in a working room using two methods: a 3-D computer simulation and a qualitative test using a smoke tube