The turbines

The steam generated in the reactor is fed through steam lines to the turbine, where the thermal energy of the steam is converted into mechanical energy. The turbine consists of two different parts: a high-pressure section and a number of low-pressure stages. 40% of the steam's energy is released in the high-pressure section and the rest is distributed in the low-pressure stages.

On O3 there are four turbines, all on the same shaft as the generator. The turbine consists of one high-pressure turbine and three low-pressure turbines. Inside the turbines, blades are mounted, the shortest in the middle and the longest at the end. Steam is fed into the center of the high-pressure turbine and then passes through the vanes out towards the edges. Changes in the speed and direction of the steam flow cause action and reaction forces. These dynamics cause the rotor shaft to rotate. In the high-pressure turbine, the steam releases about 40 percent of its energy.

After passing through the high-pressure turbine, the steam is directed to the intermediate superheaters. There the steam is heated and moisture is removed. The steam then passes to the three parallel low-pressure turbines, where it releases the remaining 60% of its energy.

The low-pressure turbines work in the same way as the high-pressure turbine. The difference is that the steam is routed to the condenser instead of to the intermediate superheaters once it has passed the low pressure turbines. The reason why we have two different types of turbines is to use as much of the energy in the steam as possible.

The generator - conversion to electrical energy

The generator is located at the end of the turbine string and it is driven by the shaft that is set in rotation in the turbines. In the generator, the mechanical energy generated in the turbines is converted into electrical energy. This is done by rotating the generator rotor in its magnetic field. Electricity with a voltage of around 20 000 volts comes from the generator.

Three to four percent of the electricity produced is used to power the entire plant. The rest is sent to a main transformer where the voltage is transformed up to 130 or 400 kilovolts. The electricity is then sent via switchgear to the electricity grid and carried via power lines to homes and other places.

The condenser

The condenser's job is to condense steam that has passed through the low-pressure turbines into water. This is done by pumping cold seawater through the tubes inside the condenser, and when the hot steam hits the cold tubes, the steam condenses into water. Before the cooling water reaches the condenser, it is cleared of seaweed and other solid objects to prevent clogging of the cooling water pipes.

As the steam condenses, the volume of the steam decreases and a negative pressure is created in the condenser. The lower the pressure, close to vacuum, the better the efficiency of the plant because the energy content of the steam is better utilized. The negative pressure means that if any of the cooling water pipes start to leak, it is salt water that leaks into the condenser, not the other way around. The process water in the condenser does not leak into the Baltic Sea.

The steam cooled to water in the condenser is pumped through low-pressure preheaters and a purification plant that removes ions in the water. High-pressure heaters then heat the water further. The water, now called feed water, is pumped back into the reactor to be reused in the process.

The cooling water used in the condenser is taken in on the southern side of the Simpevarp peninsula. It is then discharged on the northern side, into Hamnefjärden. Since the cooling water never comes into contact with any radioactive substances, it is not dangerous in the least. The only difference between the water taken in and the water discharged is the temperature. The discharge water is about ten degrees warmer than the intake water.