Call sign ENRGY80. N980ST Flew on the last day of August. Then no flights in September until the 19th. Landed yesterday at McChord AFB near Seattle.
1990 BOEING 737-400 NATIONAL NUCLEAR SECURITY ADMINISTRATION, OFFICE OF SECURE TRANSPORTATION (US Department of Energy)
The Office of Secure Transportation (OST) is responsible for the safe and secure transport of government-owned special nuclear materials in the contiguous United States. These classified shipments can contain nuclear weapons or components, enriched uranium, or plutonium. Cargo is transported in highly modified secure tractor-trailers and escorted by armed Federal agents in other vehicles who provide security and national incident command system response in the event of emergencies.
https://www.energy.gov/nnsa/office-secure-transportation