Copper-based alloys have been widely used in water-steam cycles in utility industry worldwide and will be used in cooling water system of ITER fusion reactor. Aqueous corrosion and corrosion control of copper alloys present one of the most important issues faced by utility industry. Copper corrosion is governed by multiple factors, of which the most important are:

•Water chemistry.

•Water temperature.

•Flowrate.

•Value of pH and concentration of different impurities.

Presence of copper corrosion products in water results in their deposition on heat transfer surfaces, which decreases heat exchange between metal surface ad water. If water loop is subjected to radiation, corrosion products become activated and increase total coolant activity.

This paper presents test results on the effect of two types of water chemistry – oxidizing and reducing - on copper corrosion rate in water over temperature range 25 – 250 °C. Specific conductivity of water during the tests was <0.15 µS/cm; oxygen or hydrogen was injected into water. Minimum corrosion rate of copper over the studied temperature range was observed during hydrogen injection into water with dissolved hydrogen concentration 30-60 ppb. Surface analysis of specimens showed that at these levels of dissolved hydrogen in water copper was in metallic form. This is in agreement with Pourbaix diagrams developed for this temperature range.