Corrosion of the reinforced concrete structure had been caused by carbonation and contamination of concrete by sea salt which passes through the Drumscreen Chamber as part of the Power Station’s cooling process.
Cathodic Protection works by making the encased metal surface the cathode of an electrochemical cell. A simple method of protection connects the metal to be protected to a more easily corroded “sacrificial metal” to act as the anode.
Following consultation with EDF Energy Engineers a site inspection was undertaken to examine the extent of corrosion, according to BS EN 1504 standards. A Cathodic Protection system was then installed during the summer shutdown period.
Site set up included sheeting and boarding of a scaffold dancefloor. Hammer testing of the surfaces to be repaired was undertaken. Hydrodemolition was used to remove the defective concrete from agreed areas. Replacement rebar was quantified and installed. The number of anodes required was quantified and then installed. An independent assessment of the installed system and full inspection was carried out. R4 Dry Sprayed Micro Repair Concrete was then applied to all agreed surfaces to complete the profile of the drumscreen with a derby finish.
“Cathodic Protection was specified by EDF Engineers as the primary cost-effective solution for preserving the corroded drumscreen. The successful installation and activation will significantly increase the lifespan of this structure. Cathodic Protection offered a technically sound solution because it deals with the corrosion problem across the entire area treated. This cannot be achieved with conventional repair methods without removing all the concrete where salt or carbon dioxide has penetrated.”Speaking about the project, Mick Flounders, Contracts Director at CSC Services
As part of the programme of work, CSC Services also removed existing steel ladders and platforms in the Drumscreen chamber and installed new GRP ladders, platforms and handrails.
For more information and advice about cathodic protection systems please call us on 0191 410 3444 or visit the repair section of this website.
Images of the work undertaken are shown below: