Crews have moved more than a third of the highly radioactive capsules kept underwater in central Hanford as a safety precaution.

The Tri-City Herald reports that ( http://bit.ly/LibSCV) the moves come after the 2011 Japanese nuclear disaster increased attention on preventive measures.

It's the first time a major relocation of the capsules has been done in about 20 years.

The Waste Encapsulation and Storage Facility, or WESF, holds underwater tubelike capsules that contain about a third of the radioactivity at the Hanford nuclear reservation. More than 800 of the capsules were moved within the individual underwater cells of WESF.

CH2M Hill spokeswoman Dee Millikin says work began in February and was completed six months earlier than planned