Abstract: An evaporation system for radioactive waste concentration comprises an evaporation chamber, a heat exchanger, and a circulation pump arranged in an upstanding spaced-apart configuration and enclosed within a radiation shield whereby access to the system is limited and frequently only possible from overhead. The steam chest of the heat exchanger is suspended from a removable top plate to allow removal for repair or replacement without exposing maintenance personnel to radiation. A novel circulation pump having a vertical shaft and propeller supported from a top plate which can be removed from overhead also allows maintenance or replacement of the pump without exposure to radiation or having to drain the system.