Krško N-plant offline due to a fault
Slovenia's sole nuclear power station has been shut down as a precaution after an increased but below limit value leakage was detected in the primary system. Now that the micro location of the leak has been identified it is expected to take a few weeks for the problem to be fixed.
The Nuclear Safety Administration said on 9 October that the leak had been detected on a small pipeline connected to the primary system.
The primary system's job is to produce heat and transfer it from the reactor to the steam engine.
"The location of the leak is difficult to reach, which may affect further repair procedures," the administration said, adding that the power station staff was determining the cause of the leak.
Other Slovenian and foreign professional organisations are also involved in a detailed analysis of the cause of the leak.
The administration said it was essential to find the cause, because repairing the damage without eliminating the cause would not guarantee nuclear safety in the long run, as the incident may recur.
It said it would supervise these activities and more information would be available in the coming days.
The Krško Nuclear Power Station first informed the public about the issue on 5 October, assuring it that the leak was within safe limits and did not have an impact on employees or the environment.
It then started a controlled, gradual reduction of power and by the morning on 6 October the plant was disconnected from the grid.
An inspection found that a further cooling of the plant to a cold shutdown was necessary to accurately locate the leak, taking into account the need to ensure safe working conditions. This was put in place at the weekend.
A cold shutdown means that the plant is not generating electricity and that the temperature and pressure in the primary circuit are significantly reduced, while the conditions for safe operation are guaranteed.
"Nuclear safety has also been assured since the first indication of a leak. All decisions have been and will be based on a conservative principle and a culture of high safety, which ensures the safety of employees, the public and the environment," the Krško plant wrote on 9 October.
The plant has been in contact with national and international institutions and companies to secure support for the plant to be reconnected to the grid as soon as possible. The plant said it was too early to say when this would happen.
Nuclear physicist Leon Cizelj, the head of the reactor technology department at the Jožef Stefan Institute, told the Slovenian Press Agency last week that such events were not frequent, but they were not dangerous.
"Permitted leaking is within the scope of a leaking water tap, about three litres per minute. But it is detected much sooner than this much leakage actually happens," said Cizelj, who does not expect the environment or staff will be exposed to radiation.
The power plant had previously been in continuous operation since the end of the month-long regular maintenance shutdown in autumn 2022.