The nuclear accident flags of internet lore derive from the United States' Department of Defense
, 'Nuclear Accident and Incident Public Affairs (PA) Guidance', and the United States' 'Air Force Operation Reporting System', as set out in AFI 10-206
. They are used in press releases, accident reports, and internal DoD
To quote directly from these directives, and bearing in mind that an 'incident' is less severe than an 'accident', and that those preceded by 'PINNACLE' are of the utmost severity:
BENT SPEAR - A significant incident involving a nuclear weapon or warhead, nuclear components, or vehicle when nuclear loaded.
PINNACLE - BROKEN ARROW - An accidental, unauthorized detonation or possible detonation of a nuclear weapon (not a war risk)
PINNACLE - NUCFLASH - An accidental, unauthorized, or other unexplained incident involving possible detonation of a nuclear weapon by US forces which could create the risk of outbreak of nuclear war.
PINNACLE - EMERGENCY DISABLEMENT - Operations involving the emergency destruction of nuclear weapons.
PINNACLE - EMERGENCY EVACUATION - Operations involving the emergency evacuation of nuclear weapons.
PINNACLE - EMPTY QUIVER - Seizure, theft or loss of a nuclear weapon or component.
FADED GIANT - Any reactor or radiological mishap that causes casualties, property damage, or significant release of radiological material.
Thus, a lost nuclear-powered ballistic missile submarine would fall under several of the above, as it is powered by a nuclear reactor and carries, or is capable of carrying, nuclear weapons. If the submarine was carrying nuclear weapons and could not be found, it would be an 'empty quiver', as its weapons would have passed out of US control, and depending on whether the submarine was damaged or destroyed, it would furthermore either be a 'bent spear' or a 'broken arrow'.
Any incident falling under 'pinnacle' is reported to the President, with varying degrees of urgency. NUCFLASH is the worst of the worst. There are documented instances of all but NUCFLASH being issued, with several crashed nuclear bombers, lost nuclear weapons, sunken nuclear submarines and fires at airbases accounting for the most infamous.
DULL SWORD is an Air Force reporting term which appears not to derive from a single source. It is used to mark reports of minor incidents involving nuclear weapons, components or systems, or which could impair the deployment of same. Thus, for example, all accidents involving vehicles capable of carrying nuclear weapons - armoured train carriages a prime example - are theoretically 'dull sword' incidents, as they are part of a nuclear weapons system, even if they are not carrying nuclear weapons or material at the time of the accident. A crashed nuclear bomber, even if not carrying nuclear weapons, would be a 'dull sword'. This particular codeword has caused most controversy, as there are lingering suspicions amongst non-governmental groups that some 'dull sword' incidents are more severe than made out.
ROGUE SPEAR, supposedly a means of flagging incidents in which nuclear weapons come under the control of non-governmental groups, is entirely an invention of Tom Clancy. 'Empty Quiver' is the correct term. The John Woo action film 'Broken Arrow' is therefore partially correct, as it does feature an "unauthorized detonation ... of a nuclear weapon", albeit as part of an 'Empty Quiver' incident.
The above are used by the United States of America, and are neither NATO nor global standards.