Plans for a third reactor at Oskarshamn existed as early as 1973, when an application to build a 1000 MW reactor was submitted. An order was placed to Asea-Atom/Stal-Laval but, because of the political uncertainties surrounding nuclear power, the start date for construction was postponed until a referendum could be voted on in 1980. Oskarshamn 3 was connected to the power grid on March 3rd, 1985 approximately seven months after the planned date. Maximum capacity, 1050 MW, was reached on Pentecost Monday, the 27th of May.
A power upgrade which increased maximum capacity to 1200 MW was completed in 1989. During 2011 a project was finished which increased O3's capacity to 1450 MW. Permission for the power upgrade was granted by the government and installations was implemented under 2009-2010, followed by tests during 2011-2012. New turbines, a new main circulation system, a new generator and transformer were among the changes needed to make the power upgrade possible.
A few facts
Construction began: 1980
Gross output: 1450 MW
Construction costs: 11 billion SEK (including first fuel charge)
Highest annual production: 10 TWh in 2015