Dilithium chamber hatch
The dilithium chamber hatch aboard Federation starships was a reinforced plate which fitted over the exterior entrance to the matter-antimatter reaction assembly with the dilithium articulation frame immediately behind it.

In 2367, the dilithium chamber hatch aboard the  exploded; although sabotage was suspected, a subtle manufacturing flaw in the hatch (replaced at Earth Station McKinley earlier that year) was to blame. ()
Warp