I cheated in a couple of places with spelling, but these were still fun to write.
Nothing gets out, nothing gets iN
Confined within space specifiC
Locked up body and souL
Open up! The answer’s nO
Stripped of freedom’s blisS
Unable to break thrU
Release me! The answer’s neveR
Alphabetic Explanation of the Undead
A Beetle Clawing Dirt Entered Forgotten Graves. He, Incidentally, Just Krept Last Month Near Other Places Quite Radioactively Saturated. This Unusual Visitor Would X-plain Your Zombies.