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Energy start-up is next stage for Mochovce 3 launch

Tuesday, 17 January 2023

The third unit at Slovakia's Mochovce nuclear power plant is moving onto the next phase of its commissioning after completing its physical start-up tests.

Energy start-up is next stage for Mochovce 3 launch — The Mochovce nuclear power plant (Image: Slovenské elektrárne)

Slovenské elektrárne said the tests included pressure tests of the containment, primary circuit and steam generators plus "the functionality of the reactor control and protection systems had to be verified and complex tests had to be carried out to verify all the characteristics of the reactor's active zone - first without a controlled fission reaction, later at minimum power from 10^-7 to 2% of nominal power".

Slovakia's Nuclear Regulatory Authority issued approval on Friday to move on to energy start-up, the next stage of putting the nuclear facility into operation.

In this phase the power of the reactor is increased to 5%, with further tests carried out, including simulation of "situations that the power plant will probably never experience in normal operation". The power of the reactor is increased in steps, with tests to be conducted at each stage - when the reactor power reaches 20% and a sufficient amount of steam is produced in the steam generators, "the first turbine-generator and later the second one will be phased to the electricity system of the Slovak Republic and the first megawatt-hours of low-carbon electricity will begin to flow into the grid".

The final stage will be a 144-hour trial run at full power.

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 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 them 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.