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EPR™: how it works?

The EPR™ layout offers exceptional and unique resistance to internal or external hazards, including earthquake, flooding and airplane crash.

Discover the inner workings of an EPR™ reactor plant, with each of its main components outlined below.

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The reactor containment building

The Reactor Building located in the centre of the Nuclear Island houses the main components of the Nuclear Steam Supply System (NSSS), the In-Containment Refueling Water Storage Tank (IRWST) and the core catcher. Its main function is to ensure protection of the environment against internal and external hazards, under all circumstances, including possible accident conditions.

For maximum protection, the reactor containment building (1) has 2 walls: an inner pre-stressed concrete housing with a metallic liner (B) and an outer reinforced concrete shell (A).

The outer shell (A) covers:

  • the reactor building (1)
  • the used fuel building (2)
  • 2 of the 4 safeguard buildings (3)

The remaining 2 safeguard buildings are in another location in case of damage to the reactor containment building.

The reactor containment building houses the reactor coolant system, comprising the reactor vessel (C), the four steam generators (D), the pressurizer (E) and the four reactor coolant pumps (F). Also within the containment building is a specially designed corium spreading area (G), where molten core escaping from the reactor vessel would be collected, retained and cooled in the event of core meltdown.

The reactor building, the fuel building and the four safeguard buildings stand on a single reinforced concrete basemat.

The fuel building

The Fuel Building (2), located on the same basemat that supports the Reactor Building and the Safeguard Buildings, houses an interim fuel storage pool for fresh and spent fuel and associated fuel handling equipment.

The safeguards buildings

The four Safeguard Buildings house key safety systems such as the Safety Injection System and the Emergency Feedwater System, and their support systems.

These safety systems are organized into four sub-systems or "trains". Each has the capacity to provide 100% of safety functions on its one. Each train is installed in one of the four safety buildings (3), separated by the reactor building (1). This greatly diminishes the chance of simultaneous failure of all 4 trains.The outer shell covers two of the four safety systems.

The main control room

EPR™ reactor plants feature a specialized instrumentation & control (I&C) system, located in one of the Safeguard Buildings, is fully computerized with a user-friendly human-machine interface

The control room’s instrumentation & control (I&C) system enables the operators to monitor and operate the entire plant. Equipped with the latest digital technology, the system centralizes all operating data. Operators have full control over important parameters for plant operation and access to real-time summary data. The fully digital I&C significantly reduces the risk of human error, providing operators with technical and operational support and instructions in all situations.

Specially designed access way and ventilation systems ensure the control room’s accessibility in an emergency while a reinforced concrete helps protect it from external attack. And if the control room ever becomes inaccessible, the plant can be operated from a remote shutdown station.

The diesel buildings

The emergency diesel generators (4 and I) used to back-up external power supply are housed in 2 separate buildings and supply electricity to the safety functions in the event of a power blackout.

There are 4 Emergency Diesel Generators which supply one Safety Train each as well as two diverse diesel generators as ultimate back-up.

Just like the containment building, these separate buildings are built with reinforced concrete that is highly resistant to external shock.

The turbine building

The turbine building (7 and H) contains the alternator and the condenser, the latter is connected to the grid. This set of equipment is what transforms steam into electricity.