Blaidd Drwg (Welsh for "Bad Wolf") was the name of a nuclear power plant and research facility in Cardiff.
The plant was originally planned for construction in central Cardiff. Behind the plans was Blon Fel-Fotch Passameer-Day Slitheen, posing as the new Lord Mayor of Cardiff, Margaret Blaine. The plans were to build the power plant on top of the Cardiff rift, on the site of Cardiff Castle, which was to be demolished. The power plant would have a meltdown, causing the rift to open. According to Blon, she chose the name at random, thinking it sounded good. (TV: Boom Town)
The power station was built at another location and became a functioning station. (TV: Everything Changes) Guy Wildman worked here and used his connections to steal six uranium cores for the Bruydac. (PROSE: Another Life)