VENTILATION AS BARRIER FOR AIRBORNE AREA

[Jackson_R_Ellis@rl.gov]

     I am revisiting this topic because I believe I was not specific enough 
     about the geometry of the situation.  Several suggested using the 
     heavy plastic strips found on grocery refrigerated compartments that 
     would provide separation while still allowing equipment passage.  
     Others commented that such a large opening meant the two rooms were a 
     single airspace so a barrier that provides a complete seal and a DP of 
     up to 1 inch of water was needed.
     
     A top view is provided below.  Hopefully this didn't get chewed by the 
     long distances WEB travel.
     
     
     
                             ~860'
     |--------------------------------------------------------------------|
     |                                                                    |
     |        15'                                                         |
     |       |---|                                                        |
     |       |   |                                                        |
     |       |   |28'                                                     | 
     |       |---|                                                        |
     |                                                                    |
     |                                                                    |
     |--------------------------------------------------------------------|
     
     The 25' X 28' opening is in the floor of the ~860' long larger room 
     (canyon).  The second room is below the opening on a lower level 
     (tunnel).  We wish to remove airborne rad area status from the tunnel 
     room.  You can now see refrigerated compartment plastic strips are not 
     an option.
     
     On the subject of using a solid barrier that provides a DP of up to 1" 
     of water:  The canyon room is an airborne area due to decontamination 
     activities approximately 300' - 400' away from the opening.  The 
     smaller room has no history of receiving contamination from that 
     activity.  The tunnel exhausts through the opening to the canyon room.
     
     We do not want to put a "golden line" down in the canyon room that 
     denotes the farthest distance airborne contamination will travel in an 
     open room (yet).  Workers traverse the length of the canyon room, so 
     separate controlled zones would mean dress/undress stations.  But, we 
     do want to consider the smaller room a separate airspace.  This 
     situation does not warrant a solid barrier (the requirement from DOE 
     RadCon Manual says "where practical."  However, I would like have a 
     ventilation barrier to ensure that airborne contamination (to the 
     extent that would produce 10% DAC) does not enter the tunnel room.  
     Does anyone know of a flow rate (or velocity) that is required?
     
     I apologize for the length of this message, but my last attempt to 
     abbreviate left out needed details.
     
     Thanks for your time.
     
     Jackson_R_Ellis@rl.gov