Unions at the Sellafield nuclear reprocessing plant in Cumbria have made an unprecedented appeal to workers to name a colleague who sabotaged equipment at the site. The appeal to the 10,000-strong workforce follows an incident last month in which cables controlling robotic equipment were deliberately damaged. It happened in a part of the plant that handles waste too dangerous for human workers to deal with. A police investigation has so far failed to identify the saboteur.