Ask most people to picture a nuclear power plant and they’ll probably describe the cooling towers. Some will mention the reactor. Fair enough. But a reactor doesn’t make electricity on its own. It makes heat, and something has to turn that heat into steam before a turbine can do anything useful with it.<\/p>\n
That something is called a steam generator, and on Wednesday one of them went into the reactor building of Lufeng unit 1, a plant under construction in China’s Guangdong province. It’s about 79 feet long and nearly 20 feet across. It weighs about 694 tons, too, and it’s only the first of two that unit needs.<\/p>\n
The builder is China Nuclear Industry 23 Construction Company, or CNI23, a subsidiary of state-owned China National Nuclear Corporation. CNI23 is putting the unit up under contract to China General Nuclear (CGN), and it announced the lift itself. World Nuclear News<\/a> picked the story up on Thursday, with CNI23’s summary of the job: “The entire process was safe, stable, and precisely controlled.”<\/p>\n Which is pretty much the only acceptable way to describe moving 694 tons of anything around inside a reactor building.<\/p>\n Lufeng 1 uses a design called the CAP1000, China’s version of the Westinghouse AP1000. If that name rings a bell, it’s because the AP1000 is the design running at Plant Vogtle in Georgia. Both are pressurized water reactors, and the basic idea is easier to follow than you’d think.<\/p>\n Water flows through the reactor core and picks up heat, but it’s kept under so much pressure that it can’t boil. That hot water then gets pumped through a big bundle of thin metal tubes inside the steam generator. On the outside of those tubes sits a separate supply of water at lower pressure, and that water does boil. The steam heads off to spin the turbine.<\/p>\n That means the water that touches the fuel never gets anywhere near the turbine, which is kind of the point. Basically, a steam generator is a giant heat exchanger that keeps two batches of water apart while passing heat from one to the other.<\/p>\n The CAP1000 uses two of them per reactor, each one serving its own coolant loop. And if you’ve followed our coverage of French reactors, you’ll know they do things a little differently. The Paluel plant’s unit 3 is getting four replacement steam generators at 474 tons each<\/a>, while a reactor at Cruas-Meysse is getting three that weigh about 365 tons apiece<\/a>.<\/p>\n So why is Lufeng’s so much heavier?<\/p>\n It comes down, at least partly, to the number of loops. With only two steam generators sharing the heat from a 1,250-megawatt reactor, each one has to handle a bigger slice of it than its French cousins do. And as you’d expect, a bigger slice means a bigger machine.<\/p>\n A Chinese-language write-up on CINIE<\/a>, a nuclear construction news site, fills in some detail WNN’s piece doesn’t. It matches WNN on the weight, then describes the job as a stack of headaches: the sheer tonnage, a tricky flip on site, and very little room to maneuver inside the nuclear island.<\/p>\n Steam generators usually travel lying on their side, so “flipping” most likely means tilting this one up to vertical before it went down into the containment. Doing that with 694 tons on the hook isn’t something you’d want to improvise.<\/p>\n And they didn’t. According to CINIE, the team went through several rounds of plan reviews, tabletop rehearsals, digital modeling and process simulation before the lift. It also mapped out stress risk points, tweaked the lifting path and had custom lifting fixtures made. During the lift, 3D collision checks and guide devices helped steer the steam generator through the flip, into the containment cavity and into position. CINIE says the final placement landed within the design tolerance.<\/p>\n That’s a lot of rehearsal for one lift.<\/p>\n Neither write-up says how long it took or names the crane that did it. I’d have liked to see both, frankly, since the crane was arguably the hardest-working machine on that site this week.<\/p>\nSo what is a steam generator?<\/h2>\n
Flipping it was arguably harder than lifting it<\/h2>\n
Lufeng is a six-reactor site<\/h2>\n