JEK2 Can Be Built, but Can Slovenia Build It on Schedule?

Picture a cooling tower rising almost 200 metres above the Sava River, taller than most European skyscrapers, and a convoy hauling a single 980-tonne component across 274 kilometres of Slovenian road that has to be modified in 112 separate places to let it through. That is the physical reality of building a nuclear power plant in Europe in 2026, and it is exactly what two feasibility studies released this month have put on paper for the first time.

The Slovenia JEK2 nuclear project, the planned second unit at the Krško site, has spent years defined mostly by reactor-type debates. In September 2026, two documents changed that: a cooling tower feasibility study by specialist firm John Cockerill Hamon, and a preliminary heavy-component transport study. Both arrive as the project moves into national spatial planning and approaches its late-decade referendum and procurement cycle.

What follows unpacks the two studies in enough detail to understand where the real complexity lives and what it signals for the project’s credibility as a near-term build, specifically whether JEK2 can hold its 2033 construction start or whether the numbers point to slippage.

A nearly 200-metre tower and half a country of road: what the feasibility studies actually found

Start with the cooling tower. John Cockerill Hamon evaluated four configurations for the Krško site, and the preferred option is a single natural draft cooling tower standing an estimated 193-198 metres tall, with the exact height depending on which reactor is ultimately selected.

The reasoning behind that preference is practical. A natural draft tower needs no fans to move air, which means no fan energy demand and lower maintenance over the plant’s life. The study also frames it in environmental terms, minimising thermal impact on the Sava River, a criterion that carries weight in a project this exposed to public scrutiny.

The reasoning behind that preference is practical, but it also intersects with a longer-run climate exposure: heatwave risk to river-cooled reactors has become a pricing consideration for European energy investors, as reduced river flow constrains thermal discharge and directly limits output during peak summer demand.

The secondary option is a combined natural and mechanical draft design, which would require two towers of roughly 75-80 metres each. It performs, but at higher operational cost, largely because the fans it relies on consume electricity the plant would otherwise sell.

The transport study tackles a different problem: how to physically move reactor components to Krško. From eight candidate routes, it identified a 274-kilometre corridor running from the Port of Koper, through Ljubljana and Celje, to the plant site.

The corridor has to carry components weighing as much as 980 tonnes, and moving that load is not simply a matter of driving it. The study flagged 112 separate locations requiring infrastructure modification, split across three categories:

• Bridge reinforcements to bear the load
• Road modifications for width and clearance
• Temporary removal or lifting of overhead infrastructure, including power lines and signalling equipment

A detailed final transport study is projected for completion by the end of 2028. These figures are not abstract specifications. For anyone tracking whether JEK2 is a buildable project rather than a policy aspiration, they define the floor of logistical complexity the developer has already accepted, with the harder detailed work still ahead.

Why tower height and road corridors are the same problem wearing different hats

It is tempting to read these two studies as parallel workstreams, one about cooling, one about logistics. They are not. They are interlocking decisions, and the complexity compounds rather than simply adds.

The cooling-transport dependency

A cooling tower’s type, height, and siting dictate the land-use footprint, the crane requirements, and the laydown areas needed to assemble and position it. Those same site constraints govern where heavy-lift operations can happen and how transport access routes feed into the construction area.

Choosing a single tall natural draft tower produces a very different site layout problem than two shorter mechanical-draft units. One concentrates footprint and crane demand at a single point; the other distributes it. Either choice reshapes where the 980-tonne components can be received and moved once they arrive.

That is why GEN energija and its advisers are treating the two as one integrated design problem. Dnevnik’s September 2026 reporting shows cooling tower assessments being coordinated with transport corridor design rather than advanced independently.

Technical criteria are not the whole story Bruno Glaser, Technical Director of GEN energija, noted that the cooling study factored in climate change impacts and social acceptability alongside technical performance. The final cooling system decision will still undergo additional technical verification and spatial planning before it is fixed.

What the spatial planning clock means for both

Both workstreams answer to the same regulatory instrument: the national spatial plan, or DPN. It must accommodate the tower’s physical and visual footprint and the transport corridor’s infrastructure modifications, because land-use approvals have to precede any detailed infrastructure commitment.

Preparation of the DPN formally started in February 2026, which gives both engineering workstreams a fixed clock to deliver against. The final transport study is due by the end of 2028, one year before the planned Final Investment Decision (FID) in 2029, leaving limited buffer for rework.

For readers wanting the institutional context behind Slovenia’s national spatial planning process and how it fits within EU and IAEA oversight structures, our dedicated guide to nuclear regulatory frameworks covers the key policy coordination mechanisms that shape permitting timelines for European new-build projects.

The procurement cycle sits alongside this. Supplier qualification, tendering, bid evaluation, and contract negotiation are planned to run through the end of 2028, aligned with the 2029 FID.

Here is what that interdependence tells you. A tower redesign forced by spatial planning, or a bridge reinforcement more complex than the preliminary study assumed, does not stay contained in its own workstream. It feeds back into the other and can delay the entire chain leading to FID. Project watchers should track these two as a single compounding risk, not two separate line items.

What nuclear new-build in Europe actually costs once you add the infrastructure up

The cost figure you may already know for JEK2 is the overnight cost, the price of building the plant excluding financing and inflation. On that basis, estimates cluster tightly: €9.3 billion for a 1,000 MWe unit rising to €15.4 billion for a 1,650 MWe unit, a range consistent across GEN energija’s internal estimates, an Ernst & Young review, and World Nuclear Association figures.

That is the floor. The real number climbs from there.

Once financing costs and construction-period inflation are added, the all-in figure moves to €15-22 billion, according to Balkan Green Energy News reporting in February 2026. The September 2026 Slovenian coverage put precise numbers on the gap.

For the 1,100 MW option, Siol.net reported combined investment and financing costs of €11.819 billion in constant prices, rising to €14.838 billion in current prices once expected inflation to completion is included. That is roughly €3 billion added by inflation alone, on the smaller configuration.

For the larger 1,650 MW unit, Dnevnik reported a current-price total reaching €21.8 billion.

The clearest statement of cost escalation on record GEN energija clarified to Dnevnik that the project figure has risen from an original estimate around €16 billion to approximately €22 billion once financing and inflation are fully accounted for.

For context, the closest current European comparator is the new Dukovany unit in the Czech Republic. Its engineering, procurement, and construction contract was signed in June 2025 at CZK 407 billion (approximately US$18.6 billion), and only after a legal challenge by EDF was resolved by the Czech Supreme Administrative Court.

The read you should take from the roughly €3 billion inflation gap on the smaller JEK2 option is this: schedule discipline is a primary financial risk in its own right, not just an execution detail. Every year of delay adds to the all-in cost in a way overnight estimates never capture.

European nuclear cost escalation is not unique to JEK2: France’s programme to build six EPR2 units carries a total investment envelope approaching €73 billion, and its financing and inflation assumptions face the same schedule-sensitivity that turns overnight-cost estimates into a floor rather than a forecast.

How the engineering picture changes the project’s risk profile ahead of the 2029 FID

Pull the three threads together, cooling complexity, transport logistics, and cost structure, and a single picture emerges. The cooling tower and transport corridor are two components of a shared enabling infrastructure risk that sits directly on the critical path to the 2029 FID, distinct from reactor procurement risk but interacting with it constantly.

The 2028 convergence year

The dates line up in a way that should concentrate attention. The final transport study is due by end of 2028. The procurement cycle runs through end of 2028. And the DPN, in preparation since February 2026, must reach a stage that supports both by roughly the same window.

That makes 2028 the real stress test for JEK2, not 2033. Multiple workstreams have to land almost simultaneously for the 2029 FID to hold, and because they are interdependent, slippage in one can cascade into the others.

Three variables will most directly signal whether the 2033 construction start remains achievable:

1. DPN adoption timing, since land-use approvals gate everything downstream
2. Final transport study delivery, due end of 2028
3. Procurement process completion on schedule through 2028

The Dukovany precedent is instructive here. A procurement dispute delayed the EPC contract signature until a court ruling cleared it. For JEK2, that is a reminder that a contested tender can push back an FID-equivalent milestone regardless of how well the engineering is progressing.

The referendum as an engineering communication challenge

There is a political layer sitting on top of all this. Prime Minister Robert Golob has said he expects a plebiscite in late 2027 or early 2028, before the FID, once full project information is available. The WNA August 2026 profile confirms a referendum is envisaged before the 2029 FID.

That timing turns the cooling tower choice into a public communication problem, not just a technical one. A structure approaching 200 metres is visually prominent, and voters will need it explained in terms of landscape, river ecology, and environmental footprint.

The project company has already framed natural draft towers as the most environmentally friendly option. That framing signals awareness that social licence depends partly on how infrastructure choices are explained, not only on what they are.

What the feasibility studies signal about JEK2’s buildability

Strip away the detail and two distinct claims sit side by side. The first is that JEK2 can be built. The second is whether it can be built on time and on budget. The September 2026 studies confirm the first while leaving the second genuinely open.

On feasibility, the evidence is affirmative. The 2025 technical feasibility studies found all three reactor options, EDF’s EPR and EPR1200 and Westinghouse’s AP1000, technically feasible for the site. The cooling tower options are viable. The transport corridor is identified. The cost modelling is detailed enough to support serious planning. JEK2 has cleared the “can it be done” threshold.

The “will it be done on schedule and budget” question is where the same studies raise the stakes. The 112-location corridor is the operational definition of the logistical challenge. The roughly €3 billion inflation gap on the smaller option is the operational definition of the financial risk that schedule slippage creates. Neither is a reason to doubt the project’s engineering; both are reasons to watch its execution closely.

The financial base case The World Nuclear Association confirmed in August 2026 that Slovenia is judged capable of financing JEK2 independently, the institutional endorsement the project’s economics currently rest on.

JEK2 has reached the stage where the engineering detail is finally granular enough to reveal the true shape of the challenge. The decisions taken in 2027 and 2028, the referendum, the DPN, procurement, and the final transport study, will determine whether that challenge is met or whether the 2033 construction start becomes the first casualty of its own complexity.

Nuclear capacity tripling targets, endorsed at COP28 and now embedded in national energy strategies across Europe, are the demand-side backdrop against which JEK2’s timeline risk should be read: if the global build rate required to hit 2050 goals is not achieved, the cost of any single project’s delay extends beyond Slovenia’s energy balance.

This article is for informational purposes only and should not be considered financial advice. Investors should conduct their own research and consult with financial professionals before making investment decisions.

Past performance does not guarantee future results. Financial projections are subject to market conditions and various risk factors. Forward-looking timelines and cost estimates are drawn from project sources and are subject to change based on regulatory, procurement, and market developments.