Planning Areas and Zones
For most accident types, emergency response takes place over two distinct areas:
On-site area
The area surrounding the facility within the security perimeter, fence or other designated property marker. It can also be the controlled area around a radiography source or contaminated area. This is the area under the immediate control of the facility operator or user. For transportation accidents on public roads or territories, there is in effect no on-site area.
Off-site area
The area beyond that under the control of the facility or user.
For facilities with the potential for accidents resulting in major off-site releases (planning categories I and II), the level of planning will vary depending on the distance from the facility. For these facilities, planning can be discussed for three emergency planning zones and as described as below:
Precautionary action zone (PAZ)
Predesignated area around a facility where urgent protective actions have been preplanned and will be implemented immediately upon declaration of a general emergency. The goal is to substantially reduce the risk of deterministic health effects by taking protective action before a release.
Urgent protective action planning zone (UPZ)
Predesignated area around a facility where preparations are made to promptly implement urgent protective measures based on environmental monitoring.
Longer term protective action planning zone (LPZ)
Predesignated area around a facility furthest from the facility and including the urgent protective action planning zone. It is the area where preparations for effective implementation of protective actions to reduce the long term dose from deposition and ingestion should be developed in advance.
These zones should be roughly circular areas around the facility. The size of the zones can be determined by an analysis of the potential consequences. However, previous studies of a full range of radiological and nuclear accidents provide a basis for generic zone sizes. The boundaries or the zones should be defined by local landmarks (e.g., roads or rivers) to allow for easy identification during a response. It is important to note that the zones do not stop at national borders.
