SKI reviews the final disturbance analysis from Forsmark
SKI has received a final disturbance analysis report from the licensee Forsmark Kraftgrupp, FKA, on the event on July 25 in the Forsmark unit 1 NPP. The report is a completion to previously submitted material and also to information that has reached the SKI review team.
The Forsmark analysis is an official document and can be downloaded (in Swedish) as a PDF. Due to confidentiality some of the schematic diagrammes on the electric feeding at the unit are not to be found in the material (appendices 1 and 3).
SKI’s review of the event is going on since several weeks. Our review is technical regarding what happened, in what way the unit functioned, and its safety functions. There is furthermore a review on the handling of the personnel, and of the working conditions in the control room.
SKI will come to a standpoint on the submitted disturbance analysis report and on the need for possible complementary additions.
The other Swedish reactors with a similar system design (Oskarshamn 1 and 2) are shut down on the licensee’s (OKG) initiative, as well as Forsmark unit 2. SKI is reviewing technical suggestions from the licensees in order to prevent this event from happening again in the shut down reactors.
Of specific interest is the FKA evaluation of what is the worst possible disturbance ( the power of an electric pulse through the systems). The assessment of this issue is crucial to in what way to design the various components of the safety systems.
Finding out that safety functions proved to be linked together in a delicate way is according to SKI extremely serious and this issue will therefore be specifically reviewed. The SKI will assess the mutual independence of the safety systems in all the Swedish reactors, and will continuously inform internationally about this work.
More information about the incident can be read in the preliminary IRS report below