General requirements are based on the four principles described in Section 18.2. The principle concerning external factors affecting the plant obliges the applicant to investigate all possible natural phenomena and human- induced situations which may constitute a hazard to safe operation of the future NPP. For natural phenomena such studies require the analyses of prehistoric, historical and currently instrumented information and records related to the phenomena under study. For human-induced situations, they are of use in evaluating the hazards associated with hazardous industries and activities, such as the transport of explosive, flammable and toxic mate­rials, around the site under consideration and their foreseeable develop­ment with time.

The principle concerning the radiological impact on the public and the local environment requires the investigation of all potential radiological impacts on people and the environment that may be produced from the expected release of radioactive nuclides during normal operation and acci­dent conditions.

The principle concerning the feasibility of emergency plans requires the evaluation of the present and future distribution of the population in the region of interest, the present and foreseeable future uses of land and water and the radiological risks that the affected population may support in case of accident. It is also necessary to evaluate which site characteristics or concurrent natural phenomena may occur that may hinder the efficiency of the already established emergency plan. The Fukushima event has clearly demonstrated how the major emergency situation created by the earth­quake and resulting tsunami created a nuclear emergency inside a previous, much larger, naturally induced emergency.

The principle related to the ultimate heat sink provision requires the identification of the pathways internal to the plant by which decay heat can be transferred to the environment under heavily deteriorated conditions. Damping such decay heat to the atmosphere is recommended provided that such releases do not involve the concurrent release of radioactive nuclides.