Atucha Nuclear Power Plant

The Atucha Nuclear Complex, or Atucha Nuclear Power Plant, is the location for two adjacent nuclear power plants in Lima, Zárate, Buenos Aires Province, about 100 kilometres (60 mi) from Buenos Aires, on the right-hand shore of the Paraná de las Palmas River. Both are pressurized heavy-water reactors (PHWR) of the German PHWR KWU design, employing a mixture of natural uranium and enriched uranium (0.85% of 235U), and use heavy water for cooling and neutron moderation. The other currently operating nuclear power plant in the country Embalse Nuclear Power Plant is also a natural uranium fueled PHWR but of the Canadian CANDU 6 type rather than the Siemens provided type used at Atucha. The PHWR KWU design is unique in the world: It uses a reactor pressure vessel similar to that of a PWR reactor, with fuel elements inserted from the vessel lid, that support online refueling. The fuel elements and reactor vessel are in a vertical orientation, similarly to a PWR reactor. Due to online refueling, the fuel elements are accessible for online refueling from the floor of a reactor hall and disassembly of the reactor is not straightforward like in a PWR as this is not a routine operation. The top of the reactor must be kept clear for the online refueling machine, so the control rods are inserted diagonally from the top of the reactor vessel lid near the outer circumference of the lid, and sit diagonally in the reactor core. The control rods do not converge at the center as they are also tilted in yaw and not just pitch. The reactors have separate moderation liquid, and cooling liquid circuits. The Cooling circuit connects to the sides of the vessel as in a conventional PWR, and the moderation circuit connects at the top and sides of the vessel. The Cooling water flows within the fuel channels, and there is moderation water surrounding the channels, like a CANDU reactor. There is filler material at both domes of the vessel, to reduce the amount of moderator required. The moderator and cooling water are kept at different temperatures. It is based on the MZFR reactor in Germany. Argentina owns the entire fuel cycle for the reactors including fuel assembly.

Power station data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).