page_title: NS Savannah
section_title: Reactor
hierarchical_section_title: NS Savannah / Description / Reactor
context_page_description: NS Savannah was the first nuclear-powered merchant ship. She was built in the late 1950s at a cost of $46.9 million and launched on July 21, 1959. She was funded by United States government agencies. Savannah was a demonstration project for the potential use of nuclear energy. The ship was named after SS Savannah, the first steamship to cross the Atlantic ocean. She was in service between 1962 and 1972 as one of only four nuclear-powered cargo ships ever built.
  Savannah was deactivated in 1971 and after several moves has been moored at Pier 13 of the Canton Marine Terminal in Baltimore, Maryland, since 2008.
context_section_description: Savannah's reactor was designed to civilian standards using low-enriched uranium with less emphasis on shock resistance and compactness of design than that seen in comparable military propulsion reactors, but with considerable emphasis on safety and reliability.
  The reactor was placed to allow for access from above for refueling. The 74-MW reactor is a tall, narrow cylinder, housed in a cylindrical containment vessel with rounded ends and a 14-foot (4.3 m) diameter vertical cylindrical projection housing the control rods and refueling equipment. The 50-foot (15 m) long containment vessel houses the pressurized-water reactor, the primary coolant loop and the steam generator. The steel vessel has a wall thickness varying from 2.5 inches (6.4 cm) to 4 inches (10 cm), designed to accommodate the 186 psi (1,280 kPa) (gauge) pressure generated by a ruptured primary coolant pipe. There are two 42-inch (110 cm) diameter manholes in the top of the containment vessel. Two 24-inch (61 cm) by 18-inch (46 cm) manholes in the bottom of the containment vessel are designed to admit water to the containment vessel if the ship sinks in more than 100 feet (30 m) of water to prevent the pressure vessel's collapse. The containment vessel was not occupied under operational conditions, but could be accessed within 30 minutes of reactor shut-down. The lower half of the containment vessel is shielded by a 4-foot (1.2 m) concrete barrier. The upper half is shielded by 6 inches (15 cm) of lead and 6 inches (15 cm) of polyethylene. A collision mat shields the sides of the vessel with alternating layers of 1-inch (2.5 cm) steel and 3-inch (7.6 cm) of redwood in a 24-inch (61 cm) assembly.
  The reactor was de-fueled in 1975, but the reactor remains in place. The reactor is 17 feet (5.2 m) high with a core 62 inches (160 cm) in diameter and 66 inches (170 cm) high, with 32 fuel elements. Each fuel element was 0.5 inches (1.3 cm) in diameter and housed 164 uranium oxide pellets enriched to an average of 4.4% U-235. The 16 center elements were enriched to 4.2%, and the outer 16 elements to 4.6%. The pellets were 0.4244 inches (1.078 cm) in diameter, with pressurized helium gas in the annular space between the pellets and the element walls. Twenty-one control rods were provided, 66 inches (170 cm) long, 8 inches (20 cm) across and 0.375 inches (0.95 cm) thick. The rods could be fully inserted in 1.6 seconds by electric drive.
caption: The pressurized water reactor of NS Savannah
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