Ashes to ashes?

Abstract

Damage caused by volcanic ash to the hydraulic turbines of the Electricity Corporation of New Zealand's Rangipo power station on North Island are discussed. The ash was produced by an eruption of Mount Ruapehu in September 1995. An extensive rehabilitation programme was needed at a cost of NZ$6.3, which involves the restoration of the turbines with built-in ash protection. To reduce the ash wear rate in the turbines, an interim strategy has been implemented designed to shut down generation whenever the Tongariro River is heavily contaminated. Changes to the valves, guide vane bearings, machine auxiliaries, penstock value and headworks are discussed.