This paper will present design and operating data from an aluminum anode CP system for four large (12’x12’x1500’ long - 3.6x3 .6x460M long) steel reinforced concrete tunnels exposed to moving seawater. The
actual, monitored anode current output vs polarization of the rebar measured with permanently embedded reference electrodes will be compared to the predicted design calculations. Interesting aspects of the project include the large amount of cathodic polarization observed on the outer rebar mat through the two foot (0.6 meter) thick tunnel walls and the effect of anode current loading on the aluminum anode current output.
Keywords: cathodic protection, sea water, concrete, reinforcing steel, Aluminum anodes, cooling water, current density, power plant, polarization