Atomic matter pile
From Memory Alpha, the free Star Trek reference.
The atomic matter piles were a component used in a starship's propulsion system.
Ben Finney accidentally left the circuit open to the atomic matter piles aboard the USS Republic. The mistake was discovered and reported by James T. Kirk, and as a result Finney was moved to the bottom of the promotion list. Had Kirk not closed the switch to the circuit, the ship would have blown up within five minutes. (TOS: "Court Martial")
