What refrigerant, how many lbs, and volume of space refrigerant is running through? Occupied or unoccupied space?
Automatic leak detection is usually used in conjunction with controls for release mitigation and system isolation.
This prevents refrigerant from dumping all in one location. The higher flammability/toxicity the refrigerant is, the less you are allowed to leak per volume.
ASHRAE 34 and Mechanical Code will guide you further.