Emergency classification at nuclear power plant

A four-category system is generally adopted for classifying nuclear emergencies occurred at nuclear power plants:

Emergency Classification

Radiological Impact

Description

Emergency Standby

A prescribed situation or external event which may affect the safety of the plant.

Events are in process or have occurred which indicate a potential degradation of the level of safety of the plant. No release of radioactivity is expected beyond authorised limits and there is no threat to irradiated fuel.

Plant Emergency

The radiological consequences of the emergency situation are confined to a section of the plant.

Events are in process or have occurred which involve an actual or a potential for substantial degradation of the level of safety of the plant. Any release is expected to be very small.

Site Emergency

The radiological consequences of the emergency situation are confined to the site.

Events are in process or have occurred which involve actual or likely major failure of plant functions needed for protection of the public. Any release of radioactivity beyond the site boundary is not expected to exceed the defined Intervention Levels which trigger countermeasures in Hong Kong.

Off-site Emergency

The consequence of the emergency situation extends beyond the site boundary.

Events are in process or have occurred which involve imminent substantial core degradation or melting with potential for loss of containment integrity. Areas beyond the site likely to be affected. (Note 1)

Note 1 :

GNPS and LNPS are located far away from the urban areas of Hong Kong (about 50 km). Given this distance, it is highly unlikely that HKSAR would be affected significantly following any accidental release of radioactivity from the nuclear power stations.