radioactive substance(Any substance that contains one or more radionuclides of which the activity or the concentration cannot be disregarded as far as radiation protection is concerned)
radioactive tracer(A radioactive isotope which, when injected into a biological or physical system, can be traced by radiation detection devices, permitting determination of the distribution or location of the substance to which it is attached)
radioactive waste management(The total supervision of the production, handling, processing, storage and transport of materials that contain radioactive nuclides and for which use, reuse or recovery are impractical)