Nord Pool has received the following message from SKI (the Swedish Nuclear Power Inspectorate):
A series of measures are demanded before the reactors 1 and 2 at Forsmark nuclear power plant will be permitted to restart. Any risk of failing functions in the safety system due to failures outside the plant must be eliminated and errors similar to the one on July 25th may not cause several safety systems to fail within the plant.
The Swedish Nuclear Inspectorate (SKI) has completed its review and assessment of the incident and has reviewed Forsmark Kraftgrupp AB’s application to restart reactor 1 and 2.
The requirements for the two reactors to restart are:
The battery secured net will be made more durable to high-voltage transients.
The electrical supply from the diesel generators shall be secured
Displays in the control room in the event of loss of electricity must be secured
The gas turbine connected to the plant must be possible to control from the control room.
Instructions in the control room shall be set by the board.
On July 25 a short circuit in a switchyard outside the power plant caused a failure in the reactor in Forsmark 1. SKI notes that several errors and insufficiencies were present in the plant when the incident occurred. Collectively these errors made the incident complex. The supply of electricity to the safety system did not work as intended according to the plants safety description. When the incident occurred the plant stopped automatically.
The incident did not cause any damage to the reactor. The control room personnel acted according to instructions. Cooling of the reactor was present at all times and any risk of radioactive discharge was never present.
SKI’s assessment is that it was a serious incident as safety systems were needed but did not fully work. Therefore, SKI requires changes in the electricity system at the reactors 1 and 2 making it impossible for the same malfunction to recur. After the required changes have been made SKI have to approve them before the plant is allowed to restart.
Other reactors:Oskarshamns Kraftgrupp (OKG) has not submitted any application to restart its reactor 1.SKI’s assessment about Oskarshamn 2 is that the situation allows the reactor to restart after necessary measures have been made.
Other Swedish reactors do not have any known flaws that cause restrictions of operations. SKI – 2 (2) SKI has also begun a long-term investigation based on the experiences gathered from the incident at reactor 1 in Forsmark. Future measures may therefore be needed in all Swedish reactors.
Documentation, such as a summary of the review report, decision, illustrations etc is available in Swedish and English on SKI’s website: www.ski.se.
Lysaker, 14 September 2006
For further information, please contact SKI:
Press office, phone: +46 8 698 86 99