Corrosion Management System Design for Marine Concrete Infrastructure
LOCATION: Hunterston Nuclear Power Station, North Ayrshire, Scotland
Overview
We were engaged to design a Corrosion Management System (CMS) for critical reinforced concrete marine structures at Hunterston B nuclear power station. The CMS was to extend the operational service life of the structures by at least 15 years from the point of installation, protecting the embedded reinforcement steel against ongoing corrosion within a highly aggressive marine environment. Installed in 2011 it has reached its target and remains functioning into the immediate future.
The Challenge
Marine and coastal concrete structures are subject to some of the most severe corrosion conditions encountered in civil infrastructure, driven by chloride ingress, tidal wetting and drying cycles, and long service-life expectations.
At Hunterston, previous concrete repairs had already been carried out across the jetty, link structures and Headworks ‘B’, but reinforcement adjacent to these repairs remained at risk of incipient anode formation — accelerated corrosion at the boundary between repaired and parent concrete caused by differences in electrochemical potential.
Key technical challenges included:
- Protecting reinforcement within both the repaired (incipient anode) zones and the surrounding parent concrete with no prior repair.
- Addressing corrosion risk to exposed steel guides installed on the Headworks ‘B’ columns, a client-specified requirement outside the standard reinforcement scope.
- Achieving a 15-year design life in a submerged/tidal marine environment with restricted access for future maintenance.
- Bringing the new installation into a single coherent monitoring regime alongside existing Impressed Current Cathodic Protection (ICCP) and Galvanic Cathodic Protection (GCP) systems already operating on Headworks ‘B’ and the access jetty.
Methods of protection
Galvanic Cathodic Protection System:
Our design was based on galvanic cathodic protection (GCP), using sacrificial anodes to provide long-term, low maintenance protection without the need for an external power supply or transformer-rectifier infrastructure. This approach was selected as appropriate for the target structures, providing reliable protection current to both the incipient anode zones around existing repairs and the adjacent parent concrete, without the ongoing operational input required by an impressed current system.
Protection of Exposed Steel Guides:
In response to a specific client requirement, the CMS design was extended to include protection of the exposed steel guides installed to the Headworks ‘B’ columns with submerged galvanic anodes. These guides fall outside conventional embedded reinforcement protection strategies, and their inclusion required the system design to accommodate an additional, differently exposed steel element within the same managed scheme.
Integration with Existing ICCP and GCP Systems:
Headworks ‘B’ and the access jetty already carry operational ICCP and GCP installations. Rather than operate the new galvanic system in isolation, C-Probe’s design integrates performance monitoring of the new CMS with these existing systems, bringing all corrosion protection assets across the site into a single managed scheme.
This unified approach is intended to simplify ongoing condition monitoring, support consistent record-keeping across the asset, and give the client a single point of reference for corrosion management performance across structurally and electrochemically connected elements.
Scope of Structures Protected
- Access jetty — piles and columns
- Link Structure 1 — piles and columns
- Link Structure 2 — piles and columns, and soffit
- Headworks ‘B’ — columns, including exposed steel guides
Outcome
The resulting Corrosion Management System provides a coordinated, 15-year protection strategy for reinforcement steel across four interconnected marine structures at Hunterston Nuclear Power Station.
By combining galvanic cathodic protection at repair and parent concrete interfaces with bespoke protection for exposed steelwork, and by unifying monitoring with the site’s existing ICCP and GCP infrastructure, the scheme gives the site operator a single, coherent corrosion management framework rather than a set of disconnected protection systems.
This integrated approach reflects our broader methodology for extending the service life of critical concrete infrastructure: targeting protection precisely at identified corrosion risk areas, tailoring the system to site-specific and client-specific requirements, and ensuring long-term performance can be monitored and managed as a single asset