N4 (nuclear reactor)

The N4 reactor type is a generation II pressurized water reactor designed and built by Framatome.

Design specifications
The reactor houses 205 fuel assemblies each made out of 264 fuel rods. The rods are filled with low enriched uranium oxide (UO2) pellets for a total mass of 110 tonnes. The reactor core has a diameter of 3.48 meters and a height of 4.27 meters. The pressure vessel has a height of 13.65 meters, a diameter of 4.65 meters and a thickness of 230 millimeters. The primary circuit has four loops and is pressurized at 155 bar. For safety reasons, the four steam generators are placed inside the containment building. The produced steam is directed towards a 1500 MW Alstom Arabelle turbine at a pressure of 71 bar and a temperature of 268.8 °C.

The name "N4" stands for "Nouveau 4 boucles primaires", French for "New 4 primary loops". At 1500 MWe, it is still the most powerful tier of operational reactors in France, but the new generation III EPR design of the Flamanville 3 reactor should surpass it once commercial operation begins.

List of operational N4 reactors
Only four reactors of this type are currently operating in the world : two at the Civaux Nuclear Power Plant and two at the Chooz Nuclear Power Plant. Both plants are operated by French electric utility company EDF.