European Pressurised Water Reactor

The European Pressurised Water Reactor (EPR) is a new type of reactor with a net capacity of 1,600 megawatts. EPRs are currently under construction in Finland (Olkiluoto), France (Flamanville) and China (Taishan). The EPR is also to be built in the USA and has been renamed the Evolutionary Pressurised Water Reactor for the American market for this purpose.

The EPR is a reactor of the so-called third generation. In reactor and safety development, a basic distinction is made between four generations:

• Generation I: early prototypes
• Generation II: commercial power reactors (e.g. German light water reactors)
• Generation III: advanced reactors (e.g. EPR)
• Generation IV: future reactor concepts (e.g. high-temperature reactors)

EPR as a further development of pressurised water reactors

Generation III reactors are a further development of the light water reactors (LWR) that have existed since the 1970s. Compared to the Generation IV reactors, the EPR does not feature an innovative, new design. Rather, it is a revision in the form of an evolutionary design. The main changes relate to performance, reliability, and the safety concept.

Safety of the EPR

The development of the EPR was based on advanced safety requirements and a revised safety concept. Among other things, the concept touches on the following points:

• Reduce the impact and probability of severe accidents.
  As is already the case in some Generation II reactors, important safety-relevant systems are provided fourfold and physically separated from each other. By using different, mutually independent safety instrumentation and control systems, accidents and their consequences should be easier to control. A twin-walled containment is to prevent the escape of radioactivity due to internal and external hazards. For example, the 1.8-metre-thick outer reinforced concrete shell is designed to withstand the crash of a large passenger aircraft.
• Controlling accidents with core meltdow
  A ceramic basin underneath the reactor core - the so-called core catcher - is intended to collect the molten nuclear fuel in the event of a core meltdown. This is to prevent radioactive substances from entering the ground. The mass is to be evenly distributed over a large area in the core catcher for cooling. In addition, it is cooled there by means of incoming water and a water pipe system in the concrete foundation of the core catcher (Containment Heat Removal System).
• Exclusion of certain accidents
  Technical innovations are intended to counteract previously uncontrollable accident scenarios in the EPR. For example, the probability of a failure of the reactor vessel at high pressure is to be reduced by installing diverse pressure valves.