Question: Cumbrians Opposed to a Radioactive Environment has campaigned against all aspects of the operation of Sellafield, formally known as which worst nuclear accident in Great Britain's history, ranked in severity at level 5 out of a possible 7 on the International Nuclear Event Scale? 
Sentence (from "Cumbrians Opposed to a Radioactive Environment"): Cumbrians Opposed to a Radioactive Environment (CORE) is a non-political, non-profit organisation, located in Barrow-in-Furness, which since 1980 has campaigned against all aspects of the operation of Sellafield, formally Windscale and the site of the 1957 reactor fire.
Relevant evidence: Yes