These vent stacks play a critical role in carrying the steam pipes that transport the steam from the condenser and turbines.
Regular assessment of concrete and appropriate ongoing repair and protection is essential to enhance the lifespan of any concrete structure.
The support beams for the Steam Relief Vent (SRV) quad vent stacks of the reactor were identified for structural repairs due to deterioration and our team was tasked with completing this highly-specialised work during the statutory shut down. Necessary planned remediation programmes take place every 18 months and, with a potential £1.2m loss with every day of a double reactor outage, it is key that all planned repairs are meticulously planned to be on time and coordinated with other works on site. Working 12-hour shifts over 40 days, our team ensured that all remediation work was delivered on-time and to budget for our client EDF.
The project called upon our team’s specialist expertise for a number of reasons.
The location of the beams meant that the works were carried out at heights of around 120m, working in temperatures of around 35 degrees and with heavy materials and full PPE.
Scaffolding was tightly boarded up and all materials were carried up by hand, meaning careful and co-ordinated planning from our teams.
It was imperative that no dust or grit cascaded down from the works due to the sensitive nature of the multi-million pound equipment beneath the beams. All surface preparation work therefore had to be carried out by hand, using dustless cutting and breaking with a variety of specialist Hilti tools.
Due to being a Radiologically Controlled Area (RCA), it was essential that all debris was bagged up and logged by our operatives. Our teams are specialist ECA-trained, meaning that they are qualified to enter controlled areas.
All cementitious repairs were again carried out by hand using specialist repair mortar Intercrete. This fibre-enforced, cement-based repair mortar had to be applied quickly and skilfully by our experienced team due to the heat impacting on curing times.
All of the beam repair work was reinforced with the addition of carbon fibre wrapping. With high tensile strength but minimal weight, this method can improve strength and reduce maintenance requirements without adding to the weight of a structure.
This project involved longitudinal carbon fibre strengthening, which increased both the flexural ductility and shear strength of the supporting beams.
As with all our large-scale projects, our directors Mark and Mick remained on site throughout to oversee the work and ensure delivery points were met.
All CSC operatives undergo regular training to ensure their knowledge and qualifications are up-to-date and are Confined Space and Water Jet Association qualified. The employees who worked on this project were also NVQ-level trained in concrete repair.
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