Slovenia's second reactor needs a 195m tower and 112 road works
Serguey Asael Shinder3 min readGEN energija, the company behind Slovenia's proposed second unit at Krško, presented the current status of the JEK2 project on 17 September together with two engineering studies. Both were published ahead of a planned national referendum on new nuclear, and both are about the unglamorous half of building a reactor: how to cool it, and how to get it to the site. The announcement is at https://jek2.si/.
Cooling. Engineering firm John Cockerill Hamon assessed four options. The recommended one is a natural draft tower of 193 to 198 metres — the exact height depending on which reactor is eventually chosen. Its advantages are given as reliable operation, minimal maintenance and, decisively, the lowest electricity consumption of the four: it needs no fans, because the draft is generated by the structure itself. The named alternative is a combined natural-and-mechanical arrangement using two towers of roughly 75 to 80 metres, at higher operating cost. The project company says climate change was taken into account and that the final choice will run through further technical verification and the spatial planning procedure.
Transport. A preliminary study compared eight routes from sea and river ports. The one taken forward is the 274 km road route from Koper via Ljubljana and Celje to Krško, which would require modifications in 112 separate places for height or width clearance or for bridging. A final transport study is expected by the end of 2028.
The investment decision is planned for 2028 or 2029. The company's own economics note — revision 1, prepared on data to October 2024 and published at https://jek2.si/ekonomika/ — puts overnight construction cost, in 2024 prices, at €9.8 billion for a 1,000 MWe unit and €15.4 billion for 1,650 MW.
What it means
A 195-metre tower is a visible object, and the referendum is about visible objects. Publishing the cooling study before the vote is a choice: the tower will be the tallest structure in the region and will carry a plume most days. Releasing it now, with the number attached, is better practice than letting it appear after a yes.
The tower choice is a power choice. The stated reason for preferring natural draft is that it consumes the least electricity, because it has no fans. On a plant of this size that difference is a permanent deduction from net output for sixty years or more. It is also a maintenance-free structure versus a bank of fans with bearings in it. Both arguments point the same way, and neither is aesthetic.
And 112 places needing modification is the number to keep. It is the one figure in either study that generalises: large components for a reactor of this class cannot reach most European sites over existing infrastructure. The transport study will produce a schedule and a bill for that, and those tend to be discovered late on projects where nobody ran the route in advance. Slovenia is running it four years before the first component moves.
The event was reported by World Nuclear News at https://www.world-nuclear-news.org/articles/natural-draft-cooling-tower-is-preferred-jek2-option.