At the Krško NPP, in the night from 4 to 5 October, during full power operation, an indication of a reactor coolant leak was detected in the containment.

The reactor coolant leak did not endanger the cooling of the reactor core. The amount of leak was within limiting conditions for operation. Although the Krško NPP could have continued to operate, the plant staff decided to precautionary shut down the plant.

A gradual power reduction started at 23:00 on 5 October and the reactor was finally shut down at 5:30 on 6 October. The shutdown was carried out without any problems and according to the normal procedures for regular outages. All of the reactor coolant released from the primary system remained inside the containment. There were no radioactive releases as a result of the leak or the reactor shutdown.

The SNSA was informed about this situation in the morning of 5 October 2023. SNSA inspector went to the Krško NPP after receiving the notification. The SNSA is present at the Krško NPP and supervises the activities carried out by the Krško NPP in accordance with their procedures. After the reactor shut down and all conditions for entering the containment being prepared, the Krško NPP determined the exact location of the leak on the small connecting pipeline to the primary system. The location of the failure is in an area, which is hard to access and therefore may affect further remediation activities.

The Krško NPP staff is currently investigating the cause of the leak.  Also other national and international expert organisations were engaged to analyse the cause of the leak in more detail. After the results of the analysis, the corrective actions will be carried out. In order to ensure nuclear safety in the long term, it is essential also to determine the cause of the leak and prevent possible recurrence. The SNSA will follow investigation and remediation activities carried out by the Krško NPP.

More information is expected in the upcoming days and will be shared on our website.