Chernobyl disaster waste burial site. Map showing the location of one of the many trenches (dark) used to bury radioactive waste cleared from the site of the Chernobyl nuclear disaster. On 26th April 1986 reactor number 4 of the Chernobyl nuclear power plant exploded causing huge amounts of radiation to enter the atmosphere. It is considered the worst nuclear power plant disaster in history. A sarcophagus surrounding the reactor was erected by December 1986 and a 30km exclusion zone was set up shortly after. There are estimated to be 1000 trenches like this one, but their location and contents are not yet known.