BOISE, Idaho (AP) — Federal officials are requesting a 20-year extension involving the storage at an Idaho facility of reactor core debris from the partial meltdown at the Three Mile Island nuclear power plant.

The U.S. Department of Energy in a document made public Friday is asking the Nuclear Regulatory Commission to renew a license for the storage to 2039 at its 890-sqaure-mile site in eastern Idaho that includes the Idaho National Laboratory. The reactor core debris from the 1979 nuclear accident was shipped from Pennsylvania to Idaho between 1986 and 1990.

The license to store the material in Idaho expires in 2019. The Energy Department in a March 9 letter to Idaho officials says it remains committed to a 1995 agreement to remove the material from the state by 2035.