Fission cell battery
From Tardis Wiki, the free Doctor Who reference
Fission cell batteries were a type of battery used on Red Rocket Rising. They were cheap and efficient, but very volatile. Tom Cardwell still used fission cell batteries after they had become obsolete. (AUDIO: Blood of the Daleks)
Fission cells were also used to power the lights in the Library and could apparently outlast the sun. Though this made them the ideal light source in a place meant to stand as long as the universe itself still stood, the lights were rendered useless against a infestation of Vashta Nerada so massive the Library could not keep track of them all. (TV: Silence in the Library)
