What is the difference between a coal fired station and a nuclear power station.
this is what a steam turbine driven generator looks like. (size and colour etc varies with types and manufactures)
The blue half round part is the steam turbine and the yellow part is the generator.
A coal fired station uses crushed coal to be sprayed into the fire in the boiler that heats water in the boiler heat exchanger. This water is turned into high pressure steam and fed into the steam turbine to turn the rotors at 3000 RPM. Control of the boiler is by regulating the amount of coal dust being sprayed into the boiler fire.
A nuclear power station uses uranium rods exposed to allow fission which generates heat to heat a closed circuit of water that then heats process water in a heat exchanger to high pressure steam that is then fed to the steam turbine generator exactly as the coal fired one. Control of the boiler is by regulating the amount of the nuclear rods being exposed and allowed to react to create heat.
The weight of a 30Mw unit I was working on had a weight of the generator rotor alone of around 20 tonne. All up rotating element probably in the vicinity of 30 tonne rotating at 2 pole speed of 3000RPM. Tumut 3 hydro gen rotors were above 200tonne from memory, running alot slower below 1000RPM.
A large fault on the system like a HV pole coming down in a car crash or a distribution transformer letting go etc cause a large heavy draw on the system until protection trips, usually designed to clear a fault in under a second. The rotating mass of the steam turbine and the large hydro generators rotating mass will take a bump and drop a few revs as the overload is applied. the regulator will reset the generator to 3000RPM within a few seconds after the fault is cleared and power is still exported. You were probably eating dinner and just witness a " brown out" for a few seconds. This is called the effect of Flywheel in a system. Without flywheel (or inertia) in a supply system is easily disrupted by faults or rapid changes in demand versus supply.
Gas turbines are typically much smaller Mw than steam stations and very much lighter rotating elements so not really suited to base load generator duty. Gas stations come into their own to cover peak loads as they can be bought online within minutes and shutdown quickly after everybody has cooked their dinner etc.
