Categorization of a nuclear event is the responsibility of the NGS operator. Potential categorizations are detailed below. Upon receiving a categorization, the CEM or designate (e.g. PEOC Commander) will determine an appropriate provincial offsite response level (see Table 1) as well as having additional specific actions to take.

P.1 Reportable event

A reportable event is an event affecting the reactor facility which would be of concern to the offsite authorities responsible for public safety. Triggers for reportable events include:

  1. Any event or condition that reduces the reactor facility’s capability to mitigate an emergency onsite, and which persists for longer than the allowable time limits
  2. Any event or condition that reduces the reactor facility’s capability to provide the agreed offsite emergency support, and which is expected to persist for over 8 hours, or actually does so
  3. Natural, toxic, flammable, destructive or other phenomena which have the potential to lead to a minor break (to be defined in reactor facility procedures) in the physical integrity of the nuclear heat transport system boundary or the moderator system
  4. Unexpected or unplanned activation of the emergency cooling injection system or the containment system (including box-up)
  5. Declaration of a Station Emergency, with no potential for offsite effects
  6. Any credible publicly announced threat to, or attempted or actual breach of, the facility’s security that threatens its safe operation.

P.2 Abnormal incident

An abnormal incident is defined as an abnormal occurrence at the reactor facility which may have a significant cause, and/or may lead to more serious consequences. Triggers for Abnormal Incidents include:

  1. A minor break in the physical integrity of the nuclear heat transport system boundary with no fuel failures (actual or likely)
  2. Natural, toxic, flammable, destructive or other phenomena which have the potential to lead to the major (to be defined in reactor facility procedures) break specified in Item a. under Onsite Emergency
  3. Activation of the emergency coolant injection system or the containment system (including box-up) due to a process system upset which is not reportable under any other category
  4. Declaration of a Station Emergency due to an occurrence which has the potential to result in offsite effects.

P.3 Onsite emergency

An onsite emergency is characterized as a serious malfunction that results or may result in an atmospheric release of radioactive material or is likely to result in a release at a later time. Triggers for onsite emergencies include:

  1. A major break (to be defined in reactor facility procedures) in the physical integrity of the nuclear heat transport system boundary, the moderator system, or the irradiated (or spent) fuel handling and storage system, with fuel failures but with a fully intact and functioning containment system
  2. An abnormal emission (to be defined in reactor facility procedures) of radioactive material to the atmosphere from any non-reactor source
  3. An event or condition which has the potential to lead to a General Emergency criterion, concurrent with the loss of the ability to detect or control such a development
  4. Hostile action in the protected area resulting in actual or potential loss of control over station safety or safety related systems but excluding reactor control systems.

A notification with this categorization must state whether an emission is ongoing or, if not, give a best estimate of when it is expected to commence.

P.4 General emergency

A general emergency is characterized as an ongoing or imminent atmospheric release of radioactive material as a result of a more severe accident. Triggers for general emergencies include:

  1. Damage to reactor fuel leading to the release of radioactivity from the fuel coincident with the failure, impairment, or bypass of containment, resulting in an atmospheric emission or, a reasonable expectation of an emission within the next 12 hours
  2. Hostile action in the protected area resulting in actual or imminent loss of the ability to achieve and maintain the reactor in a cold shutdown state.

A notification with this categorization must state whether an emission is ongoing or, if not, give a best estimate of when it is expected to commence.