From Tardis Wiki, the free Doctor Who reference

Dulkis was an isolated planet which orbited a minor, yellow star near the edge of a spiral galaxy.

Dulkis was hot, dry and ochre in colour when viewed from space. It had few valuable minerals, but there were some materials that could be used for nuclear fission in the northern hemisphere. Dulkis was the homeworld of the peaceful Dulcians. One of the locations on the planet was the Island of Death, a dry, rocky island in the southern hemisphere used by the Dulcians for testing nuclear weapons.

It was later chosen as the landing site by the Dominators, who wanted to use the radiation (which was drained when their ship arrived on the island) and the thin crust in the area which they would have destroyed in order to create a volcano which they could then use to convert into nuclear fuel for their fleet. (TV: The Dominators [+]Loading...["The Dominators (TV story)"])