The industrial heartland in western Japan is facing the prospect of electricity shortages over the summer in the absence of nuclear power.

Electric Power Development Co., better known as J-Power, said Thursday it won't be able to fully restore a 1,000-megawatt coal-burning generator in Nagasaki Prefecture until June 2015. The unit at its Matsuura plant, which serves western Japan, has been offline since March 28, when it was damaged by an accident during an inspection.

A power crunch could hit while Japan is completely without nuclear energy over the peak summer season for the first time in more than four decades, a legacy of the Fukushima disaster of 2011. The nation is working on a thin margin of reserves and the fear is that another plant failure could leave companies and homes without enough electricity.