GE Steam Power Systems will supply the turbine generator set for Hanhikivi 1. The set consists of a high pressure turbine, an intermediate pressure turbine, three low pressure turbines, and a generator on the same shaft as the turbines.
- The turbine-generator is based on systems developed by Alstom: Arabelle technology for the steam turbine and GIGATOP 4-pole technology for the generator.
- The overall length is almost 80 metres.
- The whole turbine-generator weighs almost 2500 metric tons (the high and intermediate pressure turbines weigh about 450 metric tons, and the three low pressure turbines and generator weigh about 500-600 metric tons each).
- The last stage of the low pressure turbine has a span of almost six metres, with blades about 1.8 metres in length.
- The turbine-generator shaft will rotate at around 1500 rpm.
- The electric power output is up to 1200 megawatts, and the plant will produce altogether about 10 TWh per year. This is over twice the electricity consumption of Helsinki, capital of Finland, and will cover about 13% of Finland’s electricity needs.
The turbine-generator will be manufactured in France. GE Steam Power Systems is a well-known and experienced supplier that acquired Alstom’s energy business in 2015. Alstom’s steam turbine-generators have been delivered to nuclear power plants all over the world.
Operating Principle of a Steam Turbine Generator
The turbine generator is the so-called a conventional part of the power plant. It is used to convert the steam generated in the nuclear island into electricity to be distributed to the national grid.
In practice, almost dry steam from the reactor unit is piped to the turbine. The steam spins the turbine blades, cooling as it does so. This transfer of heat energy makes the turbines rotate. The generator – which is on the same shaft as the turbines – converts the kinetic energy of the turbines into electricity.
Turbine generators are found in all condensing power plants, even if the steam is generated differently, for example, by burning coal.