Grand Canyon Centennial Protection Act This bill withdraws 1,006,545 acres of federal lands in Arizona, including any land or interest in land acquired by the United States after enactment of this bill, from entry, appropriation, and disposal under the public land laws; location, entry, and patent under the mining laws; and operation of the mineral leasing and geothermal leasing laws and mineral materials laws. The Government Accountability Office shall conduct a study of uranium stockpiles in the United States that are available to meet future national security requirements.