Slovenia’s Krsko nuclear plant shutdown due to leak

The 696MW Krsko nuclear power plant in Slovenia has been shut down as a precaution because of an "increased leakage of the primary system inside the containment" vessel, operator Nek said.

The shutdown of the plant, which is co-owned by Slovenia and Croatia and generates an average of 5.6 TWh/yr, was necessary to allow staff to "pinpoint the source of the leak" and "take steps to remediate it", Nek said. A "controlled phase-down" of power began on the evening of 5 October, the Slovenian energy ministry said, with the plant ending generation entirely at 05:30 local time (03:30 GMT) today, Nek told Argus. The plant is now in "safe shutdown," or "hot standby," Nek said.

Once the plant was shut down, staff began "activities to identify the location of the leakage within the containment building", Nek said. The time required to carry out repairs and restart generation at the plant "will be estimated after the detection of the source of the leakage", Nek told Argus.

The issue is related to the primary cooling circuit, the ministry said, which is "entirely inside the containment" building. The primary system produces and transfers heat from the plant's reactors to the evaporators, where steam is produced. The leak has "no impact on employees, the population or the environment" and is "below the value set as a limit by the technical specifications", the plant operator said. "Once we know more, we will share it openly with the public," Nek told Argus.

The plant has been generating continuously since it returned to the grid on the completion of its scheduled maintenance late last year. It has produced 4.85TWh so far this year, with an average output of 691MW. Krsko's generation is split equally between Slovenia and Croatia and accounts for about 20pc of Slovenia's and 16pc of Croatia's power demand.

The outage at the plant is likely to increase both Slovenia and Croatia's reliance on power imports. Both countries ended 2022 as net importers, with inflows to Slovenia averaging 155MW and to Croatia at 602MW. But Slovenia has switched to a net exporter so far in 2023 because of improved hydrological conditions and stable output from Krsko and the 844MW Sostanj lignite-fired plant. Net flows from Slovenia have averaged 256MW this year. And Croatia has narrowed its import position to 261MW, also because of improved hydrological conditions and plant outages in neighbouring countries earlier this year.

By Matt Bowen