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900 Ton Containment Vessel Bottom Head Installed At Vogtle 3
Yesterday, Georgia Power announced that they successfully lifted the first part of the Vogtle Unit 3 containment vessel into place. From World Nuclear News: "The component — measuring almost 40 meters wide, 12 meters tall and weighing over 900 tons — was assembled on-site from pre-fabricated steel plates. The cradle for the containment vessel was put in place on the unit's nuclear island in April. The completed bottom head was raised by a heavy lift derrick and placed on the cradle on 1 June, Georgia Power announced."
Georgia Power has a pretty cool gallery of high resolution construction photos (the bottom head is the background on my XBMC machine). Below the fold there is a video of the crane moving the bottom head into place.
Laron helped build the Crane that is lifting that 900 Ton vessel, and I just so happen to work for Laron :)
Unit 3 means it is the third reactor in the power plant. Vogtle is the name of the power plant (probably the name of the place it is located in). Apparently there are already 2 units installed there with Generation II reactors and they are now in the process of construction another two units with Generation III reactors of the Westinghouse AP1000 design.
Vogtle was President/Chairman of Southern Company, Georgia Power's parent company. (Southern tends to name most of their plants after company bigwigs.) Apparently, he was a real POW who inspired the motorcycle dude in The Great Escape.
-1, Too Many Layers Of Abstraction
We probably could build safe reactors
Yes, we can build safe reactors, just not water-cooled reactors. Fission reactions are "just getting warmed up" by the time water starts boiling. That is a bad combination. This is why water-cooled reactors have to operate at 100+ atmospheres of pressure. Just taking water out of the equation makes fission several orders of magnitude simpler and safer to use.
That's why we should be working on new designs based on molten salt cooling, such as LFTR. Of course we aren't doing that because too many corporations with deep pockets and long tentacles prevent Congress from funding the research. But not to worry... China has a multi-billion-dollar program underway with a thousand PhD's working on it. So eventually we'll be able to buy the reactors from them.
Still, it would be a shame to have to buy from them, when they're just commercializing technology that we (the USA) invented 50~60 years ago.
XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC
Water is a popular cooling medium because its specific heat is higher than just about anything else. If you want to transport a large amount of heat energy from one place to another, heated water is about the best way to do it.
The fact that water vaporizes when overheated or depressurized is a safety mechanism too. When water vaporizes, it absorbs nearly 7x as much energy as it takes to heat water from room temperature to boiling (2260 kJ/kg vs 4.19 kJ/kg*C). Or nearly 2x the energy it takes to heat water from room temperature to the operating temp of a pressurized water reactor. So a leak or depressurization of the water automatically and instantly results in cooling.
The large volumetric change when water vaporizes is also ideal for driving a generator. Volume change = mechanical work, which is easily captured by a turbine. Without a volume change, you're left trying to capture energy via an inefficient and bulky Stirling engine.
So yeah molten salt reactors have a lot going for them. But the use of water for cooling isn't because of some grand conspiracy. Water is just an extremely good medium for cooling and converting thermal energy into mechanical work, and was the obvious choice when reactors were being designed ~50 years ago.