Early Retirement for Pioneer Plant after 45 Years of Service

Pressrelease Monday, June 19, 2017

Unit Oskarshamn 1 (O1) is in many respects a pioneer plant and represents an epoch in Swedish engineering. It is the first commercial reactor in Sweden, the first reactor in the world in which personnel conducted work in a reactor vessel that had been in operation and the first unit at which a major modernisation project was performed. The year after the decision was made in 2015 to permanently shut down the plant was the third best production year ever for the unit and this past Saturday, on 17 June 2017, unit O1 delivered its final kilowatt hours of electricity.

On 17 June, unit O1 suffered an operational disturbance which resulted in that the unit was automatically shut down. At an extra decision-making meeting held on 19 June, the decision was made to not restart the unit, with only ten days left until the final shutdown, scheduled for 29 June.

– It has been an honour to work at O1, and I reflect upon this shutdown with considerable sorrow, Mikael Wramsjö says, production manager at unit O1. The unit has been part of a unique journey during its 45 years of operation. Approximately 110,000,000 megawatt hours of climate efficient electricity have been delivered to the Swedish grid from unit O1 since the start in 1972.

ASEA obtained the contract on 14 July 1965 to deliver unit O1 with an installed output of 400 megawatts, and approximately six years later the unit was synchronized to the Swedish grid for the first time. The first commercial reactor in Sweden was inaugurated under pomp and circumstance by King Gustaf VI Adolf on 18 May 1972 during pouring rain. This was a milestone in the development of the carbon dioxide-free electricity system which Sweden can be proud of having today.

These 45 years of operating time of unit O1 has been filled with pioneering projects, furthering the development within the global nuclear power industry as well as within Swedish engineering. Project FENIX, completed in 1993–1995, included a number of measures taken to recondition the reactor vessel. This work received international attention since it was the first time in the history of the nuclear power industry that personnel performed work in a reactor vessel that had been in operation. Project MOD, performed in 2001–2003, involved the most extensive measures ever performed at OKG since the construction of unit Oskarshamn 3 (O3), and developed in many respects the oldest commercial nuclear power plant in Sweden into the most modern one.

– The unit has kept its standards high and it is amazing to see this huge commitment with respect to operating the unit to the very last minute. I have been fortunate enough to lately meet many of our co-workers in the control room and I am always very proud of the comprehensive attitude I encounter. During all conversations, the same issues are always addressed; safety, personnel and the plant. I would like to thank you all very much for keeping a high standard of motivation, says Johan Dasht, Managing Director of OKG.

A short outage period will now commence at unit O1 and the work with transporting all the spent nuclear fuel to the central interim storage facility for spent nuclear fuel will subsequently be initiated, scheduled to be completed by the turn of the year 2018–2019.

Unit Oskarshamn 1 facts:

Construction commenced: 1966
Commissioning: 1972
Maximum output, gross: 492 MW
Maximum output, net: 473 MW
Thermal power: 1,375 MW
Best production year: 2004 (3,536.46 GWh)
Production days: circa 11,000 days
Total production: approximately 110,000,000 MWh

The three best years (availability):
1. Year 1991 – 88,9 %
2. Year 1987 – 88,6 %
3. Year 2000 – 88,1 %

The three best years (net production):
1. Year 2004 – 3 536,46 GWh
2. Year 2008 – 3 496,38 GWh
3. Year 2016 – 3 367,27 GWh

To read more about the history of unit O1, click here (only in Swedish)


For information about any changes, please refer to the website of the Nordic power market, nordpoolspot.com. Information about our current production is available at our website About our production.

Press contact

Communications and Public Relations

E-mail: info@okg.uniper.energy

Phone: +46 491-78 75 50

Johan Dasht

Managing Director

Phone: +46 491-78 75 23

Mikael Wramsjö

Production Manager O1

Phone: +46 491-78 74 16

Page updated Tuesday, June 20, 2017