Fission lamp

A fission lamp was a type of lamp used around the 50th century. They were very powerful and ran on fission cells. According to the Tenth Doctor, they would outlast the sun. The Library made extensive use of fission lamps. Nonetheless, they were no match for a swarm of Vashta Nerada, whose spread was slowed down by the light from the lamps but not stopped. The sheer number of the creatures blotted out the lights one by one and quickly plunged an entire wing of the Library into darkness, sending both the Doctor and Donna Noble running for their lives as the Vashta Nerada closed in to devour them. (TV: Silence in the Library)