Hapthoid reactor unit

A  was a type of nuclear reactor untilised by the Cybermen for the means of space travel.

In the 19th century, fragments of the reactor of a Cyber-ship that had crashed in Klimtenburg were made into jewellery by Vadim and Nefta and gifted to other villagers, leading to an outbreak of Hapthoid Radiation Sickness. The Eleventh Doctor and Olga Bordmann helped gather up these fragments for the Doctor to dispose of.

After the reviving Cybermen were defeated during their attack on the village, the Cyber-ship and the reactor unit powered down and the radiation dissipated. The Doctor, however, still recommended it be buried beneath the sealed tunnels. (PROSE: Plague of the Cybermen)