Unit Oskarshamn 3 Restarted According to Plan after the Outage – Problems Detected during the Power Ascent

Pressrelease Thursday, June 18, 2015

On Sunday 14 June, unit Oskarshamn 3 (O3), the largest boiling water reactor in the world, was restarted according to plan after the annual outage had been completed. However, the power ascent had to be discontinued due to disturbances in the turbine plant, and analysis and measures are currently being performed in order to restart the facility.

The annual outage at unit O3 started on Sunday 24 May, and the unit was again able to deliver electricity to the grid according to plan on Sunday 14 June. Due to a valve leakage in the feed water system, turbine vibrations and problems with a valve in the conventional turbine plant, the power ascent had to be discontinued and the unit shut down in order for measures to be taken. Analysis and measures are currently being performed in order to restart the unit as soon as possible.

This year's outage at unit O3 was a short one, but it involved a great deal of scheduled activities. The time determining activities concerned the refuelling and the rearrangement of fuel assemblies in the reactor vessel. Moreover, service has been performed on for instance pumps and various valves included in important safety systems surrounding the reactor vessel. The inspections of the high pressure turbine valves, pumps in the main cooling water system and the high pressure preheater in the conventional turbine plant also received great focus.

The outage at unit O3 was in various perspectives a success, concerning the work environment, the reactor safety as well as the quality of the work performed.

– I would like to thank all our employees and contractors for their great commitment, which made it possible to finish the work in time according to plan, says Johan Dasht, production manager at O3. This is one of many clear results and effects of the extensive improvement work pursued in the last few years and which has been continuously run at OKG. Once the unit has been restarted, we can look forward to stable electricity deliveries from the largest boiling water reactor in the world until the outage next year.

At unit Oskarshamn 1 (O1), testing is currently being performed after the annual outage, and the facility has thus at present varying output figures. The safety modernisation in progress at unit Oskarshamn 2 (O2) is at the same time in an intense phase involving commissioning of a number of systems and components, and the unit is scheduled for restart on 20 December.

For further information on any changes, please see the website of the Nordic Power Exchange, nordpoolspot.com. You can also find updated production information on our website Production information.

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E-mail: info@okg.uniper.energy

Phone: +46 491-78 75 50

Page updated Thursday, June 18, 2015