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 out burn the sun. (TV:Silence in the Library)