It really is not comparable. Sellafield also does spent fuel reprocessing and, like all nuclear energy production, poisons the environment during regular operation: https://www.theguardian.com/uk/1999/nov/20/paulbrown
I would emphasize _historically_, but as a matter of interest, the Hanford site hosts multiple currently-operating reactors (including CGS and several research reactors) and contains the fuel processing reactor FFTF - it has been shut down for a couple of decades now but there is some ongoing interest in resuming operation.
