The state is appealing a decision by the Nuclear Regulatory Commission to renew the operating license of the Pilgrim nuclear power plant in Plymouth for another 20 years.
Attorney General Martha Coakley’s office said an appeal was filed on Monday with the US Court of Appeals in Boston.
Coakley said the NRC abused its discretion by relicensing the plant without fully considering safety issues that were raised by the accident at the Fukushima nuclear plant in Japan after last year’s earthquake and tsunami.
Pilgrim’s original operating license expired on June 8.
NRC officials said the 6 ½-year review period for the plant’s renewal application was the longest in the agency’s history.