The maintenance will involve the replacement of fuel and 25 technological upgrades that will improve the power station's safety and reliability, NEK chairman Stane Rožman told the press on Thursday.

Special attention will be dedicated to fuel, after a suspected flaw was detected in February on at least one fuel rod.

A total of 56 fuel elements - essentially bunches of fuel rods - will be replaced and all fuel inspected visually and with ultrasound.

To prevent damage to nuclear fuel, a system will be put in place to prevent vibrations that appear to be the cause of the cracks.

Additionally, one of the two low-pressure turbines will be overhauled.

The upgrades will involve security systems installed mostly in the aftermath of the Fukushima disaster in 2011.

About 1,000 contractors will take part in the maintenance, according to Rožman.

The scheduled maintenance comes after over 500 days of uninterrupted operation at full capacity.

NEK provides around a quarter of all electricity produced in Slovenia.

Slovenia's only N-plant, which began commercial operation in 1983, is jointly owned by Slovenia and Croatia.

While it was originally designed to be shut down by 2023, the consensus is that its useful life should be extended beyond that.

In 2014, Slovenia's sole N-plant successfully underwent a three-year review performed every ten years as part of certification or continued operation.

The tests, conducted by experts at NEK and its subcontractors and verified by a group of international experts, checked all of its vital safety systems.