Modernisation projects at units 1&2 of the Mohovce nuclear power plant in Slovakia should increase production by 450GWh a year, without higher fuel or personnel costs, power utility Slovenské elektrárne (SE) said.
After shutting down one of the two turbine generators at Mohovce 2 on 15 August, and after it had cooled down, SE said it had begun to dismantle the high-pressure and low-pressure parts of the turbine marking the start of a key part of the large and demanding modernisation project to increase efficiency.
The work will result in approximately a 7% increase in the power of both units, from 471MWe to 500MWe. The combined, the output will increase from 942MWe to 1000MWe. SE will first increase the output of Mohovce 2, which will supply increased electricity to the grid from November. Work will be completed at Mohovce 1 by the spring of 2021.
The modernisation will involve the replacement of the complete high-pressure part and flow sections of low-pressure parts of both turbines at Mochovce 2 with modified and more efficient ones. Turbine oil regulation and control will also be changed due to the electronic turbine regulator replacement. In addition, the work involves the overhaul of valves, fittings, flaps around turbines, replacement of moisture separators upstream of turbines and feedwater nozzles, and the replacement of current and 15.75kV voltage converters behind generators. The replacement will continue with 400kV unit transformers and other works in electric and I&C systems, explained plant director Martin Mráz.
"The turbine's output at a cooling water temperature of 21.5ºC will be 250.72MWe, but the current technology enables even further increase in the unit's efficiency," said Mráz. "Once the turbines are modernised, we will perform warranty measurements, which will show us potential reserves for a further possible increase in the output of the secondary circuit equipment - particularly separators, high-pressure and low-pressure heaters. The service life of the turbines after their modernisation will be 40 years."
SE completed similar modifications at the Bohunice V2, where electrical output was increased in 2010.
Photo: Aerial view of four units at Mohovce nuclear power plant (Photo credit: SE)