Seaweed ingress of cooling water intakes with predictions for Torness power station

Abstract

Seaweed ingress into the cooling water intakes of nuclear power stations has caused several disruptions to electricity supply. Seaweed is transported by tidal and wave-induced currents after dislodgement from the sea bed following stormy conditions but ingress will be shown to be not only determined by wave conditions. An integrated model system has been developed to predict such ingress and applied at the Torness power station in Scotland where the mass of seaweed recovered was measured for some ingress cases. Prior to each case, seaweed is assumed initially to be distributed in areas surveyed within the surrounding coastal domain with a mass per unit area based on local measurements. Criteria for dislodgement are based on near-bed velocity. Six cases where the mass of ingress was measured and two cases with no ingress have been modelled and predicted by adjusting a dislodgement factor (a multiplier on the threshold velocity) within a relatively narrow range.