Slovenske elektrárne (SE) has begun hot hydro testing at unit 4 of the Mochovce NPP in Slovakia. This will involve pressure and leak tests of the primary circuit and reactor, functional tests of primary and secondary circuit equipment, safety systems, air conditioning, electrical engineering and control systems.
Slovenske elektrárne Chairman and CEO Branislav Strýček said the project to complete Mochovce 4 in has achieved significant milestones including a cold hydro test that resulted in a small revision. “With the hot hydro test, we are in the next stage of the inactive testing programme. Our goal is to load fuel into the reactor this year after all necessary tests and revisions have been completed, so that we can generate even more electricity in Slovakia reliably and without direct CO2 emissions.”
SE noted that during the cold hydro test, the primary circuit was heated to 130°C and pressurised to 13.7 MPa, which is more than 111% of the operating pressure. SE also tested feed water pipes and steam to a pressure of up to 7.65 MPa – 166% of the operating pressure. Mochovce unit 3, which began operation in 2023, passed the same tests.
Richard Green, project director for the construction of nuclear units at Mochovce said the project “was advancing in accordance with the schedule approved by the shareholders, for which we owe the professionalism and commitment of the project team.”
Construction of the first two 471 MWe VVER units at the four-unit Mochovce plant began in 1982. Construction of units 3&4, which started in 1986, was frozen in 1992. Units 1&2 began operation in 1998 and 1999 and work to complete units 3&4 resumed in 2009 but faced a series of delays. Units 3&4 with a design life of some 60 years, will supply some 26% of Slovakia’s total electricity consumption.
SE has two shareholders. The majority shareholder is Slovak Power Holding BV (SPH), which owns 66%. In SPH, 50% of the share capital is owned by the Czech energy group Energetic & Primense Holding (EPH) and the remaining 50% by the Italian company Enel. The Slovak Republic has a share of 34% in power plants.
In December 2024, Enel and EPH signed an agreement under which EPH, as envisaged by the early redemption option, would buy 50% of the share capital currently owned by Enel in SPH. The closure of the transaction, which is expected in the first half of 2025, is conditional on the fulfilment of certain conditions, including approval by the regulatory authorities.
