Sentence:  There are a large number of nuclear and radiological facilities, including legacy sites worldwide, that have been <WSD>decommissioned</WSD> successfully, are either currently in an active <WSD>decommissioning</WSD> phrase, or will require <WSD>decommissioning</WSD> in the near futurenb.... 
Meaning of the word marked with <WSD> tags:  To take out of service or to render unusable.