North Carolina, which relies on nuclear power for nearly half of its electricity, is home to some of the nation’s highest concentrations of radioactive waste.

The state ranks fourth in the nation for accumulated nuclear waste, according to a report issued Tuesday by the Institute for Policy Studies, a left-leaning advocacy group in Washington, D.C.

The waste has been stored for decades at Duke Energy’s McGuire plant near Charlotte, and Progress Energy’s Shearon Harris nuclear plant in southwestern Wake County and Brunswick plant near Wilmington.