What constitutes a 'nuclear weapon accident'?

A 'nuclear weapon accident' is characterized by an event that results in the unintentional detonation or release of nuclear material. This definition is critical as it captures the potential for severe consequences associated with nuclear weapons, ranging from environmental contamination to serious safety risks for personnel involved. Such events are typically unexpected, highlighting the importance of stringent safety protocols and comprehensive training to prevent these scenarios.

In contrast to this definition, enhancing nuclear readiness refers to measures intended to improve preparedness but does not imply an accidental scenario. A malfunction of nuclear equipment may lead to various types of problems but doesn't necessarily equate to a nuclear accident; it could pertain to non-nuclear aspects. A planned demonstration of nuclear capabilities also does not fit the definition, as it involves intentional and controlled actions rather than unintentional events. Thus, option B accurately encapsulates the essence of what a nuclear weapon accident entails.