RESIDUAL RADIOACTIVITY

Nuclear radiation that results from radioactive sources and persists for longer than one minute. Sources of residual radioactivity created by nuclear explosions include fission fragments and radioactive matter created primarily by neutron activation, but may also be created by gamma and other radiation activation. Other possible sources of residual radioactivity include radioactive material created and dispersed by means other than nuclear explosion. See also contamination; induced radiation; initial radiation.