Method for treating waste water from the decontamination of a metal surface, waste-water treatment device and use of the waste-water treatment device

A waste water treatment apparatus for treating waste water from decontamination of a metal surface in a primary coolant circuit of a nuclear reactor, said apparatus comprising:

• a discharge device provided for discharging a predetermined amount of a primary coolant comprising an oxidizing agent from the primary coolant circuit,
• a reduction zone that is connected to the discharge device and comprises a dosing station for introducing a reducing agent into the predetermined amount of the primary coolant discharged from the primary coolant circuit, and which reduction zone is provided for the reaction of the reducing agent with the oxidizing agent in the primary coolant to form a reaction solution, and
• an ion exchanger connected to the reduction zone for deionizing the reaction solution.