The turbine operator both operates the turbine and controls the water flow in the system, as well as the steam pressure. There are two main valves used for these purposes. The bypass valve directs steam from the separators directly to the condenser, resulting in steam wastage. It should be used when the turbine is not running or when trying to synchronize the turbine to handle excess steam flow. The turbine inlet valve directs steam through the turbine and then into the condenser again. The latter valve can obviously be used only when the turbine is running.
The amount of steam generated by the reactor depends mostly on temperature and, therefore, is influenced by reactor power. At low power levels, when there is not much steam, the operator should keep the valves closed to allow the pressure to build more quickly. On the other hand, when approaching 7 MPa of pressure, the valves should be opened to prevent further increases. The more the valves are open and the higher the reactor power, the more water will flow through the system. Therefore, everything must be coordinated with the Reactor Cooling Operator, so they can maintain proper water levels. Fast changes are not recommended, as the operator might not be able to adjust the valves quickly enough. Additionally, the Condenser operator should be aware of these changes, as steam flow dictates the amount of condenser circulation flow needed to maintain the proper vacuum level.
Please be advised that the bypass valve cannot handle full reactor power. Therefore, the reactor power should not be raised too high if the turbine is not running. Only a turbine valve can maintain enough flow to cool a reactor operating at full power. If the turbine trips at full power, an automatic reduction to 10% of power will be initiated. At lower power levels, it might be possible to keep the reactor operational, but you will still need to provide offsite power to Main Bus A on the electrical panel for the pumps.
The pressure rate indicator tells us whether the pressure is rising or falling and should be primarily used when approaching the maximum pressure of just over 7 MPa to precisely control and stop at the desired level.
The turbine can be started whenever there is sufficient pressure available (5Mpa-7Mpa) and the condenser maintains the proper vacuum level (refer to the Condenser panel) using the 'Turbine Man Valve' switch (In Unit #2 the whole procedure is much more complicated, please refer to Turbine_Control_Room part of the manual). From that moment on, the inlet valve will control the turbine's speed. In reality, it is important not to accelerate the turbine too quickly (In Unit #2 high vibrations will trip the turbine). The turbine can be synchronized at around 10% of reactor power, which should provide enough steam to accelerate the turbine to 3600 RPM while still maintaining pressure well below the maximum. When approaching the desired speed, the operator should slightly close the valve to slow down the acceleration, ideally maintaining a speed of 3600 RPM or very close to it. Synchronization won't be successful if the turbine speed changes too rapidly. If the pressure increases significantly at this stage, the bypass valve can be used to bring it back in line.
There is an automatic turbine run-up control available where desired turbine RPM can be selected (0, 900, 1800, 2700, 3600) with a desired acceleration (S - Slow, M - Medium, F - Fast). It will operate turbine valve automatically to reach desired RPM.
Once 3600 RPM is reached, press the 'Breaker 52G1' (*'Synchronize' in Unit #2) switch. If successful, the governor will maintain a constant 3600 RPM, and the steam flow through the valve will determine the generator load. In other words, the more steam that flows through the turbine, the more electricity it will produce. Users with Operator+ rank and everyone in Unit #2 will be also required to keep the synchroscope close to the top when synchronizing the turbine.
While steam directly generates energy, it's the reactor that determines how much energy can be produced. For instance, the operator can open the valve to increase the generator load, but this will cause a drop in steam pressure, making it difficult to sustain the higher load. To further increase the generator load, reactor power must be increased. This will result in higher pressure, and after balancing all flows, it will lead to increased electricity production. Power can be raised to 100%, resulting in approximately 1200 MW of power, with all major pumps operating at around 75% load. Theoretically, the reactor can be powered up to 120% (though it will shut down beyond that point), which can yield 1500 MW of power with nearly 100% pump load. However, this should not be done under normal circumstances.
Once synchronized, automatic pressure control can be enabled. It will maintain the pressure at the desired level of 7100 kPa, but it will result in a reduction in earned points.
During manual control, the following procedure should be used to meet the power demand. First, a rough power setting should be achieved, roughly equal to the demand/110 (i.e., 500 MW demand corresponds to 45% of power), while maintaining the desired pressure of 7.1 MPa with the turbine valve. Once the power is stable, the proper demand should be set with the turbine valve, taking into account the current site power needs (ensuring that power sent to the network matches the demand). At this point, the turbine valve is considered to be set up, but the pressure, and therefore power production, may still tend to change. These changes should now be corrected solely by adjusting the reactor power. If the load drops, power should be increased; if it increases, power should be reduced. Keep in mind that pressure and load changes will have some natural lag in response to reactor power changes, so it is advised not to make rapid adjustments to the reactor power. Ideally, the power sent to the network should stabilize around the demand, with the reactor's response period approaching infinity.