EDF, owner of all nuclear power plants in France, initiated the Extrados project to improve leak-tightness on concrete enclosures that are subject to pressure in several of its nuclear power plants.

To provide an alternative solution to existing systems in the market, GDES undertook an innovation project to design a new coating system for the leak-tightness of double-walled containment structures in the reactor building (SIKAWRAP 230C SYSTEM).

SIKAWRAP 230C was designed to be applied to the external face of the internal containment structure (Extrados) and to improve leak-tightness, resistance to backpressure, and good adhesion to concrete walls. This system, developed and approved by GDES, benefits from an exclusive agreement for application on all nuclear power plants owned by EDF.

Once optimised and characterised, the SIKAWRAP 230C coating system was applied by GDES at the Cattenom 3, Flamanville 1 and 2 nuclear power plants; under the Extrados Project, 10,500 m2 of surface area were treated between 2016-2019.

This major project was developed for EDF within the “Grand Carénage” programme and represents a solution for extending the life of the nuclear power plants that have been treated.

The Extrados contract, valued at 26 million euros, entailed 4 different interventions. An average of 180 people, specifically trained by GDES, worked on each intervention and a total of 200,000 man-hours have been accumulated in the four years of study, design, approval of the SIKAWRAP 230C system and execution of the works.

Our client has verified the effectiveness of this innovative coating system by means of pressure tests – for both resistance and leak-tightness – on all the treated containment buildings. The last test, on Flamanville 2, was performed in September 2019 and, as in all previous tests, the criteria and requirements issued by the French Nuclear Safety Agency (ASN) and EDF were successfully met.

The Extrados project has demonstrated the capacity of GDES, on a large scale, to organise and coordinate the human resources required to participate in the phases of complex operations in French nuclear power plants. GDES has shown its capacity for technical innovation in developing real solutions to a specific and complex problem, meeting the requirements specified by the customer. It is also testament to the successful internationalisation of the GDES group with, in particular, its capacity for collaboration and internal organisation between the different departments and locations in which the Group operates.

GDES has been working in France for several years and is currently focusing on surface treatment, waste management, chemical cleaning, decommissioning and engineering technology projects for the nuclear industry.

Its commercial division has been active in France since 2007 and was consolidated as one of the group’s main international commitments in 2016 with the acquisition of the nuclear-industrial division of Erba, a specialist in industrial painting and anti-corrosion coatings.

GDES is also the only Spanish company to hold CAEAR certification to undertake services for CEA (the Atomic Energy Commission) in France and the second non-French company to acquire it.

The excellent results together with our client’s commendation after the pressure tests carried out on the Extrados project have positioned us as a leading supplier of specialised painting services and surface treatments in the French nuclear sector.