Nuclear Energy and Nuclear Disasters. "A nuclear incident is defined as an event or a series of events, either deliberate or accidental, leading to the release, or potential release, into the environment of radioactive materials in sufficient quantity to warrant consideration of protective actions". (EPA, Manual of Protective Action Guides and Protective Actions for Nuclear Incidents, 1991, p. 1-1; Health Physics Society, Guidance for Protective Actions Following a Radiological Terrorist Event, 2004, p. 3)