The operator of the Fukushima Daiichi nuclear plant began work on Friday morning to dismantle the cover of the No.1 reactor building, NHK WORLD News reported.

The cover was installed after the March 2011 nuclear accident to prevent radioactive dust from dispersing. The reactor experienced a hydrogen explosion at the time of accident.

Tokyo Electric Power Company plans to remove the cover in order to clear away radioactive debris on the upper part of the building and remove spent nuclear fuel still stored inside. It is part of an effort to decommission the reactor.

For about one week, workers will spray chemicals over the debris inside the cover by using a remote-controlled crane to prevent radioactive dust from spreading.

They will proceed with the work to remove the cover over the period of about one year. Company officials say they will enhance monitoring of radiation levels during the procedure.

TEPCO says a preliminary test last year showed no scattering of radioactive materials when dismantling the cover.