Context and challenges

The ten-yearly visit (VD) of Tricastin unit 1 was a major challenge for the site and more broadly for the fleet. Its success made it possible to obtain the first operating permit for operation beyond 40 years, as well as the deployment of the "Grand Carénage" at the power plants in the park.

The technical modifications of the Grand Carénage are based on 4 themes:

  • Safety reassessment, the objectives of which are to reduce the radiological consequences of accidents without core meltdown, to avoid massive releases and the lasting effects on the environment of accidents with core meltdown, to reduce the risk of meltdown of spent fuel assemblies stored in the pool, to improve the resistance of the installation to the hazards listed in the INB Order
  • The integration of the Fukushima REX: the deployment of the Hard Core
  • Improvement of the ergonomics and performance of the installation
  • Controlling ageing: maintaining qualifications

In order to successfully meet the challenges of the Grand Carénage, this client, a mayor player in the nuclear industry, requires expertise and technical skills in several fields (Electricity - Project Management - Logistics - Coordination - Civil Engineering - Automation - Boilermaking - Valves and fittings - Piping).

This client called on Assystem to provide technical support in the supervision of maintenance works and shutdowns of the CNPE and thus carry out various methodological assistance services (drafting of documents, updating of the information system, etc.) and work monitoring as part of project management assistance (preparation and coordination of technical activities).

Project scope

Equipment Qualified to Accidental & Safety Conditions:

  • Writing of the "Dossiers d'Aptitude à la Poursuite de l'Exploitation" (DAPE) - Support to the Unit COnformity Review (ECOT) project - Participation in the Exemplary Maintenance of the Installation (IMEE) activities

Local modifications:

  • Monitoring of the works (fitting out of the control rooms - fitting out of the treatment plant - main access station airlock - Removable handling means), integration of documents into the client IS and integration into the preventive system.
  • Production of files analysing the electrical and mechanical consignments to be made for the integration of each modification of the Decennial Inspection 4 and a schedule of the Parent Schemes.

Transverse professions:

  • Support for packaging, work coordination and nuclear waste management
  • Co-activity management

National modifications: Grand Carénage / Post Fukushima

  • Integration of VD4 changes in documents and operating schedules (Consignments - Master Plans - Periodic Tests - Technical Operating Specifications)


  • Optimization of the duration of the following VDs thanks to the constitution of a VD4 feedback and capitalization of the modifications for the next VD4s in the Grand Carénage base.
  • Optimisation of downtime by removing and/or re-planning activities from the overall shutdown programme thanks to the implementation of an approach to control the volume of maintenance work (shutdown/run arbitration).
  • Capitalization and industrialization of modification files on the various trades (Valves, mechanics, boilermaking, etc.).
  • Optimisation of interfaces with the client's business teams by setting up integrated teams.
  • Optimization of the follow-up of field activities thanks to the contribution of digital tools for the follow-up and the establishment of activity reports (gains on the non-quality of maintenance and thus on safety, improvement of the "metal" time (time dedicated to the technical gestures of the maintenance intervention), no double entry of the recorded field data, simplified archiving, ...).
  • Availability of trained engineers ready to operate (resource scarcity context).
  • Customer satisfaction reflected in the renewal of services for the next VD4.

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