The design of Susquehanna, and all nuclear plants in the United States, is based on a “defense-in-depth” concept, which refers to the multiple layers of protection for public health and safety. At the center are design features to contain radiation within the plant and minimize the release of radioactive material in any event. The design includes redundant safety systems and imposing concrete and steel barriers. Beyond physical barriers are carefully developed work procedures and extensively trained personnel to ensure consistency and safety.



  • Fuel is formed into ceramic pellets that hold in most radioactive byproducts of nuclear fission.
  • The Susquehanna plant has multiple levels of safety systems, all of which can operate manually or automatically.
  • The reactor vessel has steel walls 4 to 9 inches thick.
  • Surrounding the reactor is a containment structure made of 6-foot-thick concrete with a quarter-inch-thick steel lining.
  • Pipes that pass through the containment structure walls typically have valves both inside and outside containment for added safety.
  • The reactor building, which has steel-reinforced concrete walls, serves as a secondary containment structure.
  • To prevent air leakage, air pressure inside the reactor building is kept slightly lower than outside air pressure.
  • Multiple plant cooling systems, a variety of water sources and a series of independent emergency core cooling systems ensure an adequate water supply to maintain proper fuel temperature.
  • An air filtration system minimizes the effect and continuously monitors airborne radiation releases during an emergency. Computers analyze the data and weather conditions to help public officials decide whether to order people to take protective action in the unlikely event of an emergency.
  • Susquehanna has several independent power sources that supply electricity to plant systems.



A detailed emergency plan is in place to protect the public in the unlikely event of a serious accident. The plan has the support of local, county, state and federal governments, and is tested several times a year.



Susquehanna has training programs in 11 separate disciplines for plant employees. These training programs are fully accredited by the National Academy for Nuclear Training.