According to the IAEA recommendations, the nuclear emergency plans

usually consider several classes of emergency, which depend on the expected

consequences of the accident scenario considered for planning:

• General emergencies involve an actual or substantial risk of release of radioactive material or radiation exposure that warrants taking urgent protective action off the site. Upon declaration of this class of emer­gency, action shall be promptly taken to mitigate the consequences of the event and to protect people within on-site and off-site zones.

• Site area emergencies involve a major decrease in the level of protection for those on the site and near the facility. Upon declaration of this class of emergency, action shall be promptly taken to mitigate the conse­quences of the event, to protect people on the site and to make prepara­tions to take protective action off the site if this becomes necessary.

• Facility emergencies involve a major decrease in the level of protection for people on the site. Upon declaration of this class of emergency, action shall be promptly taken to mitigate the consequences of the event and to protect people on the site. Emergencies in this class can never give rise to an off-site area or general emergency.

• Alerts involve an uncertain or significant decrease in the level of protec­tion for the public or for people on the site. Upon declaration of this class of emergency, action shall be promptly taken to assess and mitigate
the consequences of the event and to increase the readiness of the on-site and off-site response organizations as appropriate. Alerts include events that could evolve into facility, site area or general emergencies.

Design and implementation of the emergency plans are carried out in three phases:

• The planning phase consists of a detailed analysis of the situation that can occur at the facility. The result of this analysis is used to define the characteristics of appropriate emergency measures, to mitigate the con­sequences of every credible event. The results of the analysis are used to establish the emergency plan that accurately describes the organiza­tion in charge of implementing countermeasures; emergency actions to be taken in each case; a clear allocation of responsibilities of every individual participating in the implementation of emergency measures; intervention criteria; decision-making procedures for countermeasures implementation; definition of planning areas; and the means and resources needed for intervention.

• The preparedness phase consists of the identification, acquisition and putting into optimum use conditions of means and resources to inter­vene in case of emergency. Preparation includes also training of inter­vention personnel and maintenance of the technical, human and organizational means and resources, as well as the verification that all of them are permanently in a position to be activated. A crucial element during the preparedness phase is conducting partial or full-scale exer­cises for training the intervention personnel and verifying the appropri­ateness of emergency plans.

• The response phase consists of the activation of the emergency organiza­tion, as soon as possible, to cope with a real or simulated accident, through the implementation of countermeasures foreseen in the emer­gency plans with the available means and resources. The response phase starts with the decision of activating the plan after an accident occurs. This decision is taken by the operator in the case of on-site emergency plans and by the relevant authority in the case of off-site emergency plans. The response phase includes implementation of urgent mitigation and protective emergency measures, and undertaking appropriate reme­dial actions in the medium and long terms until bringing the situation to a safe condition. The response finishes when the normal situation has been recovered as far as possible.

Operators and public authorities responsible for the implementation of the nuclear emergency plans periodically conduct a review in order to ensure that situations that could necessitate an emergency intervention are identified, and to ensure that an assessment of the threat is conducted for such practices or situations. This review is undertaken periodically to take into account any changes to the threats within the State and beyond its borders, and to learn from experience and lessons from research, operating experience and emergency exercises.