A specific purpose that must be accomplished for safety. Safety Standards Series No. NS-R-1 lists 19 safety functions to be fulfilled by the design of a nuclear power plant in order to meet three general safety requirements: (a) the capability to safely shut down the reactor and maintain it in a safe shutdown condition during and after appropriate operational states and accident conditions; (b) the capability to remove residual heat from the reactor core after shutdown, and during and after appropriate operational states and accident conditions; and (c) the capability to reduce the potential for the release of radioactive materials and to ensure that any releases are within prescribed limits during and after operational states and within acceptable limits during and after design basis accidents. This guidance is commonly condensed into a succinct expression of three main safety functions for nuclear power plants: Control of Reactivity; Cooling of Radioactive Material; Confinement of Radioactive Material. In earlier IAEA publications, 'basic safety function' and 'fundamental safety function' were also used