Fission lamp

A fission lamp was a type of lamp used around the 50th century. They were very powerful. 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. (DW: Silence in the Library)