The Composition-B compression explosive was a mix of TNT, RDX and wax. For training missions such as this the plutonium pit was removed but everything else was as in the live weapon, so it could still have made a mighty-but-conventional bang.
Pedantically this wasn't a BROKEN ARROW ( unauthorized use ) but EMPTY QUIVER ( loss or theft of weapon or component thereof ).
> Pedantically this wasn't a BROKEN ARROW ( unauthorized use ) but EMPTY QUIVER ( loss or theft of weapon or component thereof ).
If we're being pedantic, this wasn't EMPTY QUIVER either, though, was it? Both BROKEN ARROW and EMPTY QUIVER are events involving nuclear weapons, but this one had lead instead of plutonium, so it was no longer a nuclear weapon.
It was a "component" of a nuclear weapon (the other component being the plutonium core).
A cannon doesn't stop being a cannon just because you take out the gunpowder and fill it with sand. It may not be at risk of going off accidentally, but it's still a disaster to lose track of one if cannon design techniques are a closely-guarded state secret.
The device lost is still considered a nuclear weapon in the sense that should it fall into enemy hands, it would help the enemy develop their own weapons and understand the limitations of your weapons.
Pedantically this wasn't a BROKEN ARROW ( unauthorized use ) but EMPTY QUIVER ( loss or theft of weapon or component thereof ).