The utility model discloses a nuclear power station steam generator washes sediment reaction unit collects three major parts of metering unit including reaction subassembly, acid gas absorption and drainage assembly, liquid. Through the exquisite design of each part, connection, the prerequisite of testing accuracy and precision with each subassembly quantity confirmation in insurance validity of experimental apparatus drops to minimumly, utilizes the drainage to detect the hydrogen volume that generates and has realized the accurate swift survey to fe content in the nuclear power station steam generator sediment.