Westinghouse Electric Company has launched a comprehensive six-month Front-End Engineering & Design (FEED) study to assess deploying one advanced AP1000 modular reactor at the Jaslovské Bohunice NPP in Slovakia. This will advance engineering, licensing, and detailed project planning.
The project is spearheaded by JESS (Jadrová energetická spoločnosť Slovenska). Slovak state company JAVYS (Jadrová a vyraďovacia spoločnosť) recently acquiring the 49% stake in JESS previously held by Czech utility ČEZ, ensuring the project remains exclusively state-owned. The buyout paved the way for Slovakia to build a new reactor at the existing Jaslovské Bohunice site, using existing infrastructure with an estimated project cost of at least €10.9bn ($12bn) targeted for completion by 2040.
Financing for the new nuclear unit is partially supported by a grant from the US State Department’s Foundational Infrastructure for Responsible Use of Small Modular Reactor Technology (FIRST) programme. It builds upon an intergovernmental civil nuclear agreement signed by both countries in January.
The FEED study will provide JESS with the necessary project baseline, including preliminary budgets, environmental suitability, and structural scheduling, to dictate subsequent deployment phases. Slovakia aims for a target operational date of 2040 for the plant.
“Today we are signing the first technical document that allows Westinghouse to find out exactly what condition the construction site is in, where we are located, what permits are needed and so on.“ said Prime Minister Robert Fico. during the signing ceremony of the contract.
“The political will of the government to build this resource is very clear. We want to make decisions to ensure that this process is irreversible after the next parliamentary elections in 2027,” Fico stressed, noting the key role nuclear plays in Slovakia.
Slovakia shut down two units of the older VVER-440 units at the plant in 2006 and 2008 as a condition for European Union membership. The site currently hosts two VVER-440 units commissioned in 1984 and 1985, operated by Slovakia’s largest electricity producer, Slovenské elektrárne (SE).
In addition, four VVER-440 units are operating at the Mochovce NPP Units 1&2 began operation in 1998 and 1999, unit 3 in October 2023 and unit 4 earlier this year. With all six units in operation, nuclear power should cover approximately 77.5 % of domestic electricity consumption. These ensure not only energy self-sufficiency, but also the ability to export electricity abroad.
The US-Slovak agreement signed in January specified:
- Codifying the Slovak government’s mandate to retain 100% state ownership of the upcoming reactor;
- Supplying standard and Western-sourced nuclear fuel to break Slovakia’s legacy supply-chain dependence on Russian-designed reactors;
- Jointly establishing safety best practices, optimising nuclear supply chains, and initiating regional engineering training programmes; and
- Incorporating a simultaneous framework signed by US and Slovak export banks to coordinate long-term financing mechanisms once construction starts. The U.S. State Department’s FIRST Program (Foundational Infrastructure for Responsible Use of Small Modular Reactor Technology) is a capacity-building initiative designed to help partner nations safely and securely deploy advanced civil nuclear energy solutions.
The FIRST programme acts as a vehicle to promote American nuclear technology abroad, directly countering Russian and Chinese dominance in global civil nuclear export markets. It provides expert-led consultation to help countries align their regulatory, legal, and licensing frameworks with international non-proliferation and safety standards.
Rather than financing full plant construction, the programme provides grants for critical pre-construction work. The grant allocation for the six-month Front-End Engineering and Design (FEED) study covers:
- Site verification matrix – funding the comprehensive assessment of the Jaslovské Bohunice site layout, examining geological structures, cooling parameters, and existing environmental permits.
- Technology adaptation assessment – underwriting the technical alignment necessary to integrate a Generation III+ passive-safety 1,100–1,200 MWe AP1000 large reactor onto a grid originally built for smaller VVER-440 units.
- Financial & logistical deliverables – producing detailed financial frameworks, specifically a fixed preliminary schedule, capital expenditures (CAPEX) budget forecasts, and baseline licensing workflows. The aim is to give JESS the mandatory data to push for irreversible investment action before the 2027 parliamentary elections.
While the FIRST programme explicitly features SMRs in its acronym, its scope encompasses all advanced civil nuclear technologies. The foundational framework of the FIRST programme states that it is designed to support countries considering “SMRs or other advanced reactors”. The AP1000 is classified as a Generation III+ advanced reactor. Because it uses modular construction techniques, it shares the same assembly philosophy that defines the SMR movement, even if scaled to 1,200 MWe.
Integrating a 1,200 MWe AP1000 reactor into a grid originally designed for smaller units presents distinct engineering and electrical challenges. Grid operators must adhere to the N-1 criterion, which dictates that a transmission system must withstand the sudden, unexpected loss of its single largest generation asset without triggering a widespread blackout. Slovakia’s current largest contingency risk is a single 500 MWe VVER unit.
Tripling that risk to 1,200 MWe requires Slovakia’s transmission system operator (SEPS – Slovenská elektrizačná prenosová sústava) to secure vastly larger spinning reserves – backup power sources that can immediately ramp up within seconds to stabilise the grid frequency if the AP1000 trips offline.
Injecting 1,200 MWe from a single point requires massive transmission capacity to move that power away from the station without overheating the lines. Existing 400 kV substations and transmission lines surrounding the Jaslovské Bohunice site must be thoroughly modelled. The FEED study will evaluate whether these lines require upgrading to high-capacity conductors to prevent thermal overloading during peak generation.
Because Slovakia sits at a vital junction of the Central European power grid, a massive power surge at Bohunice will alter loop flows into neighbouring Czechia, Hungary, and Ukraine, requiring multinational coordination.
Large synchronous generators like the AP1000 drastically alter the short-circuit ratio and fault levels of the surrounding network. The intense electrical current that could potentially flow during a grid fault (short circuit) will rise significantly with a 1,200 MWe generator online. The FEED study will assess whether nearby substation circuit breakers need to be replaced with higher-rated equipment to safely clear faults.
The AP1000’s massive turbine-generator must dynamically balance reactive power to maintain grid voltage stability within strict regulatory limits during sudden load fluctuations.
