It is shown that conventional nuclear flowmeters do not function satisfactorily in polymer injection wells or in water injection wells at low flow rates. In polymer wells, accurate injection profiles depend on the variable "shot" duration of the radioactive "tracer" material. The conventional nuclear flowmeter ejects tracer material perpendicular to the logging instrument which may cause it to stick to the wellbore wall or fail to reach the maximum flow region. In water injection wells, sidewall mixing of radioactive tracer material is apt to cause inaccurate injection profiles. These and other problems have led to the develop- ment of a new generation of nuclear flowmeters: the Swing-Arm Tracer instrument and the Basket Nuclear Flowmeter instrument.