The core of the ALMR is a cylinder 1350mm long and 1570 mm in diameter. The core consists of hexagonal assemblies that are all cooled and enclosed in individual coolant tubes. There are driver fuel, blanket, GEM, control rod, reflector, and USS assemblies (these assemblies are described following this card). The average power density over the entire core is 180 kW/L. The core can run two years between refuelings and each reactor will only be out of service for 18 days. Refueling is accomplished using the In-Vessel Transfer Machine.
The reactor vessel is a cylinder 18.7 m long and 5.7 m in diameter. It will be made of grade 316 stainless steel. The reactor vessel contains the core and most of the reactor components submerged in liquid Sodium. The space above the Sodium but below the top of the reactor vessel is filled with Helium at atmospheric pressure. The core sits in the very bottom of the vessel.
