Atucha II is a nuclear power plant in Argentina, located in Lima, Buenos Aires, on a site next to Atucha I. Its construction started in June 1981 under a contract with Siemens. Like Atucha I, it is a Pressurised Heavy Water Reactor (PHWR), but was planned to have a much higher power (thermal power approx. 2,000 MW, electrical 750 MW). At the time when it was started, it had the largest reactor pressure vessel of any nuclear power plant worldwide.