On Tuesday, 31 January 2023 at 10:57 PM, Slovenské elektrárne has connected to the grid the first of the two turbine generators of the Mochovce 3 nuclear power plant. The plant reached this important milestone less than three weeks after the Nuclear Regulatory Authority of the Slovak Republic gave its approval for the beginning of the power start-up on 13 January 2023.
“Today marks a major milestone – for Slovenské elektrárne, the nuclear power community and the entire country. As of today, Unit 3 is already converting the thermal energy released in the reactor into electricity. This will help us fulfil the agreement with the Government, in which Slovenské elektrárne committed to supply cheap electricity to Slovak households at the price of 61.2077 euros per megawatt hour, which represents an unprecedented low price in the EU. Congratulations to my colleagues and thank you to all those who have done their utmost so that we could achieve this important moment today. The new unit will make a significant contribution not only to energy stability, but also to the commitment to reduce greenhouse gas emissions on the road to carbon neutrality.”
Branislav Strýček, Chairman of the Board of Directors and CEO of Slovenské elektrárne, a.s.
First electricity in the grid
After the transition to power start-up, tests were conducted successively at the levels of 5, 15 and 20% of the reactor’s rated power, with measurements and tests of both nuclear and non-nuclear parts of the plant. The secondary circuit was heated up and steam lines blown down, cold and hot flushes of turbine condensers and low-pressure regenerators as well as feedwater lines were done, and tests of steam generator relief valves were carried out, which were heard in wider vicinity of the plant.
After successful preparation and performance of the tests necessary to start the turbines, steam was brought into the turbines for the first time over the weekend (28 and 29 January), spinning them step-by-step up to their rated speed of 3,000 rpm.
Slovenské elektrárne, a.s. also tested functionality of all electrical protections of the generator itself, the block transformer and finally the 400 kV line connecting the plant to the power system via the Veľký Ďur substation. Electricity will flow along this route to Slovak consumers.
Once this part of the power start-up was completed, Slovenské elektrárne, a.s. could proceed to the actual synchronisation of the first turbine-generator with the grid at 20% of the reactor’s nominal power and the Mochovce 3 began to supply the first electricity to the grid.
Challenging series of tests
However, a large part of the second stage of the so-called “energy start-up” is still ahead of Slovenské elektrárne. The unit is still to be tested at various power levels ranging from 35% to 100%.
“In the following weeks, the new unit will supply electricity to the grid with short-term planned shutdowns, according to the new unit commissioning schedule,” explained Martin Mráz, Director of Mochovce Nuclear Power Plant.
The full functionality of Unit 3 and the achievement of the design parameters will be confirmed by successful completion of the 144-hour proof run at full power.
New unit in the Slovak power market context
The new nuclear unit in Mochovce will have the installed capacity of 471 megawatts at start-up, which will cover approximately 13% of Slovakia’s total electricity consumption. In terms of electricity production, Slovakia will thus become energy self-sufficient already in 2023.
The lifetime of the new unit is planned to be 60 years at least.
Seven out of ten Slovaks support nuclear energy. Up to 60% think it is safe to generate electricity in a nuclear power plant. This is shown by the results of an ACRC public opinion poll conducted for the Slovak Society for Foreign Policy (SFPA) and Slovenské elektrárne in June-July 2022.
About Slovenské elektrárne, a.s.
Approximately 70% of all electricity generated in Slovakia comes from Slovenské elektrárne. Thanks to nuclear power plants in particular, Slovakia’s largest producer supplies almost 95% of its electricity without emitting carbon dioxide, which is considered to be one of the greenhouse gases responsible for global warming. The company is the only one in Slovakia and Eastern Europe to be included in the prestigious Financial Times’ Europe’s Climate Leader 2022 index for reducing emissions.
In addition to nuclear power plants, the company operates 31 hydro, two thermal and two photovoltaic power plants. Their total capacity is 4143.8 megawatts.
The company has two shareholders. The majority shareholder is Slovak Power Holding B.V. (SPH) with 66.0000000523 % stake in the share capital. In SPH, EP Slovakia B.V. (a subsidiary of the EPH Group) holds 50 % of the share capital and the remaining 50 % belongs to Enel Produzione S.p.A (a subsidiary of the Enel Group).
The minority shareholder of Slovenske elektrárne, with a 33,9999999477 % share in the share capital, is the Slovak Republic, on behalf of which acts the Ministry of Economy of the Slovak Republic.
Source: Slovenske Elektrarne