pure, pure water. that pure water boils off. it steams, causes huge amounts of pressure and the pressure goes out through that pipe. >> so these rods come in, they hit the water, they steam. >> yep. you have to be careful how much steam you make. they become up and down here with these control rods controlling how many neutrons are flying around in there, the control rods slow down the reaction. you take the control rods out, you get a lot of reaction and you have to -- >> it comes through here. now you have the turbines moving. >> do you need more or less power? is it day, night, more power or less power? you can do that by those rods. you spin it through here and you spin it through eventually it's still steaming here, goes into a condenser that is cooled by outside forces. >> opposite, it makes the steam back into water. >> it condenses it just like you put a glass of ice water on the bar. eventually you'll get a puddle of water. that's the puddle of water you