Emergency planning lies within the IAEA Fundamental Safety Principles. Technically it is also considered as the last level of protection against acci­dents with external radiological consequences. Principle 9 requires that ‘Arrangements must be made for emergency preparedness and response for nuclear or radiation incidents’. Emergency planning is a responsibility of government; arrangements should secure adequate response at the local, regional, national and even international levels, when required.

The line of responsibility for taking urgent decisions needs to be defined well in advance. In nuclear power plants, emergencies generally start within the plant and, as demonstrated in Fukushima, nuclear emergencies can be started by natural or manmade emergencies. During an onsite phase, the licensee is responsible for actions taken under the supervision of the regula­tory authority, following well-known and rehearsed procedures. An alert situation should be declared quickly when there is no evidence that the plant can be brought under control. At that moment, an offsite emergency plan is initiated and conducted under the responsibility and authority of local, regional and state authorities, as the case may be, with the advice of the regulatory authority and with help and information provided by the licensee.

Public protection actions may include shelter, evacuation, decontamina­tion, medical treatment (when necessary) and prophylaxis activities, such as ingesting potassium iodide to block radioactive iodine from entering into the body. Arrangements should include well-trained human resources, emergency procedures and reliable equipment, suitable installations and services for evacuees. National and international information, as well as humanitarian help to the people affected, are required.

Any inconvenience that people may suffer from emergency protection activities has the advantage of avoiding or reducing radiation exposure. These inconveniences are related to the conduct of periodic drills which often involve the nearby population. In case of real emergencies, remaining under shelter and being evacuated or displaced for long periods of time (as in the cases of Chernobyl-4 and Fukushima-1) are problems that affected people have to suffer. Decontamination of affected buildings to allow the return of evacuees and the restoration of agricultural soils can take a long time and create inconveniences to people’s lives. These remote circum­stances should be compared with the benefits that the neighbouring popula­tion will receive with certainty.