Slovakia soon to be the world's first in the share of electricity from nuclear sources.

Successfully inserting 349 nuclear fuel elements into the Mohovce 4 reactor marks the transition from the construction phase to the commissioning phase, and when Mohovce 4 is brought online – Slovakia will surpass France in the share of electricity obtained from nuclear sources

The company Slovenské elektrárne announced that it has successfully completed the process of loading nuclear fuel into the reactor of the Mochovce Nuclear Power Plant (Mochovce 4). The process, which lasted five days, was completed on Friday, July 3, 2026, thereby this block of Soviet design VVER-440 (Pressurized Water Reactor) officially entered the pre-critical testing phase under the strict supervision of the Nuclear Regulatory Authority of the Slovak Republic (ÚJD).

Nuclear fuel in the form of uranium dioxide is placed into the reactor core, distributed in 312 fuel elements and 37 control elements (assemblies). After the upcoming core physics tests, the reactor power will be gradually and controllably increased in small steps, all the way to final connection to the grid and commercial operation.

History of the project and the continuity of knowledge

However, what makes the story of the Mochovce plant's fourth unit unique on a global scale is its duration. Construction of the first two units of this plant began as far back as 1982, while work on units 3 and 4 began in 1986 – on the eve of the Chernobyl disaster and several years before the dissolution of the Eastern Bloc.

Due to lack of funds and geopolitical turmoil, work on blocks 3 and 4 was halted in 1992 and frozen for sixteen years. The project to complete them was launched only in 2008, and the total investment for both blocks eventually exceeded 6.7 billion euros. The third unit was put into commercial operation in October 2023, and with the completion of the fourth block Slovakia finally closes one of the longest and most complex chapters in its energy history.

From the perspective of transition and the position of newcomer countries in the nuclear sector (including Serbia), the Mochovce example is a very important lesson: Slovakia managed to finish a project started in the previous century solely because, despite a pause of a decade and a half, it managed to preserve the nuclear substance – the domestic engineering staff, the continuity of the regulatory body and operational know-how.

Slovakia as a world leader by the share of nuclear energy

Technically, Mochovce 4 will have a capacity of 471 megawatts. When this unit reaches full operating power, the nuclear reactors (along with those at the Bohunice plant) will cover a record 77.5% of Slovakia's total electricity production. With this result Slovakia will rise to the very top of the global list, ahead of France in the share of electricity derived from nuclear sources. True, this will apply only to domestic electricity production, because Slovakia remains a net importer of electricity.

The ownership structure of Slovenské elektrárne is also interesting, reflecting the pragmatic European model of "multistakeholder" partnership: the majority owner is the Czech energy consortium Energetický a průmyslový holding (via the SPH holding), while the Slovak state retains a 34% controlling stake.

The Slovak government does not stop there – and there are already plans for the construction of a new large block in Bohunice, as well as active exploration of the potential for introducing small modular reactors (SMR). The confidence that Slovak society and decision-makers have in nuclear energy is a direct result of decades of safe exploitation and a system that was not built on PR hype, but on fundamental expertise and continuity of institutions. This is a model that regional decision-makers in the Balkans should seriously look up to.

S.A.