Refer also to ASHRAE 15. Check if there is an open flame burner in the same room as the chiller. If there is, eithe partition it off or interlock it to shut it off on refrigerant leak detection.
I would also spec alarm lights at the exterior of the room ..... The refrig monitoring panel shall contain alarm light and audible device ..... Also spec 2 SCBA tanks/systems (1/2 hr min) located outside the machine room preferably in the operator's office nearby. ..... I locate the operator's room in between the boiler and chiller rooms when they are in the same general locale.
S.O.O.:
1. High Level
2. Fan On
3. Alarm to notify Plant Security and Manager
4. Plant Manager notifies
SCBA qualified maintenance personnel to investigate.
5. Leak Rate determination initiated