Major accidents are rare events which have the potential for large-scale loss of life, catastrophic damage to assets or the environment. These are specifically defined in the Safety Case Regulations. They can include:
Fire, explosion or the accidental release of dangerous substances, including hydrocarbons;
Major structural damage to the installation and/or loss of strucural stability;
Any other event with the potential to cause multiple deaths or serious injuries.
In simple terms, types of incidents that are low likelihood but have the potential to cause multiple fatalities and damage to plant and equipment.