Slovenské elektrárne says that after successful start-up tests, and the launch of steam turbines over the weekend, the new unit 3 at the Mochovce nuclear power plant was connected to the grid for the first time at 20% of its nominal power at 10.57pm on 31 January.

The Mochovce nuclear power plant (Image: Slovenské elektrárne)

Branislav Strýček, Chairman and CEO of Slovak Power Plants, said: "Today represents a fundamental milestone for Slovenské elektrárne, the community of nuclear energy workers and the entire country. As of today, the third unit converts the thermal energy released in the reactor into electricity. This will help us fulfill the agreement with the government, in which Slovenské elektrárne undertook to supply cheap electricity for households at a price of EUR61.2077 euros (USD66.7) per megawatt hour, which represents an unprecedentedly low price of electricity for households within the EU.

"The new block will significantly contribute not only to energy stability, but also to the commitment to reduce greenhouse gas emissions on the road to carbon neutrality."

During the energy start-up process so far tests have been carried out at increasing power levels - 5%, 15% and 20% - of the reactor's nominal power. The company said: "After successfully preparing and carrying out the tests necessary for the start of the turbines, over the weekend, steam was brought into them for the first time, which gradually spun them up to the nominal speed - 3000 revolutions per minute."

Tests were also completed on the generator itself, the block transformer and the 400 kV line connecting the plant to the electricity system. "After completing this part of the power start-up, Slovenské elektrárne could proceed to the actual phasing of the first turbogenerator to the network at 20% of the nominal power of the reactor and the third unit ... began supplying the first electricity to the network."

The next stage of the launch process will be to test the block at levels from 35% to 100%, with the final step due to be the successful completion of a 144-hour trial run at full 471MWe output.

Martin Mráz, director of Mochovce plant, said that in the coming weeks "the new unit will supply electricity to the grid with short-term planned shutdowns, according to the new unit commissioning schedule".

Construction of the first two 471 MWe VVER units at the four-unit Mochovce plant started in 1982. Work began on units 3 and 4 in 1986, but stalled in 1992. The first two reactors were completed and came into operation in 1998 and 1999, respectively, with a project to complete units 3 and 4 beginning ten years later. Unit 4's schedule has been to follow about one or two years behind unit 3. Each of the units will be able to provide 13% of Slovakia's electricity needs when operating at full capacity.

The final design includes many upgrades to safety and security, including increased aircraft impact protection and emergency management measures based on lessons from the Fukushima accident which were incorporated during the project. The Slovak Nuclear Regulatory Authority issued the final authorisation for commissioning of unit 3 of the Mochovce nuclear power plant in August. The service life of the new block is initially planned to be 60 years.

Researched and written by World Nuclear News