FRM II produces free neutrons by utilizing the chain reaction of the fission of uranium. In lay terms, such systems are referred to as "nuclear reactors". A nuclear reactor is said to be "critical" if the number of neutrons produced and the number of neutrons absorbed is equal. In this case, the facility is at constant power in a stable equilibrium state.

The main components of FRM II are

  • the fuel element, which provides the supply of uranium (the reactivity reserve),
  • the different cooling circuits, which dissipate the heat generated by the fission process,
  • the regulatory and control systems, e.g environmental monitoring
  • extensive safety systems for nuclear, conventional safety as well as plant reliability,
  • the beam guidance systems that transport the neutrons to the experiments and
  • numerous auxiliary and ancillary systems, from the provision of desalinated water to air conditioning, the disposal of waste water, crane systems and transport vehicles and many other facilities.