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Is thorium the energy source we've been waiting for?
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PostPosted: Apr 08, 2009 8:03 pm 
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S. Korea develops process to cut time, cost to build nuke reactor
Yonhap English News
8 April 2009

SEOUL, April 8 (Yonhap) -- South Korean engineers have developed an innovative construction method that can cut nuclear reactor building time and costs, a state-run atomic power company said Wednesday.

The Korea Hydro & Nuclear Power Co. (KHNP) said the new steel plate concrete (PC) building method may reduce overall construction time by 10 months while saving 200 billion won (US$147 million) for every two 1,400 megawatt reactor units built. A commercial reactor usually takes seven years to build at a cost of trillions of won, depending on power output.

The company said the PC method uses prefabricated sections made by two steel plates embedded with "studs" that are made at factories and shipped to the construction site. Once they are in place, concrete is poured into the space between the plates to form solid walls.

"This method is safer, faster, reduces environmental pollution and can be used in the construction of industrial plants and other facilities," a KHNP spokesperson said.

In the past, contractors relied solely on the reinforced concrete method to make specially designed walls at nuclear power plants that required steel reinforcement bars to be built in place, molds to be set up to outline walls, and the space created by the molds filled with cement.

The official said the SC method is roughly two years ahead of similar research being conducted abroad.

It said all new reactors in the country are to use this construction method.

The country plans to build eight new reactors by 2016. Twenty are in operation at present, which met roughly 36 percent of the country's energy needs as of late last year.

After starting its nuclear power generation in 1977, Seoul has rapidly caught up with industry leaders and is one of a handful of countries in the world able to design and construct reactors.


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PostPosted: Apr 09, 2009 8:09 am 
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This is only for the containment inner structures wright?

Because a containment needs (or at least where I'm from) to be made with pre-stressed concrete.

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PostPosted: Apr 09, 2009 8:32 am 
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STG wrote:
This is only for the containment inner structures wright?

Presumably.
I'm not familiar with the details.
Maybe its possible to embed pipes in the concrete, as you're pouring, which you could then run prestressing cables through later ?
Sounds like an awful lot of steel though....


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PostPosted: Apr 09, 2009 8:52 am 
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you would also be bending your steel structure which bends your concrete and can crack...

Though for the internals it is quite interesting as it could prevent containment inner structure damage during severe incidents, preserving a coolable geometry and natural circulation

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PostPosted: Apr 09, 2009 9:31 am 
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STG wrote:
you would also be bending your steel structure which bends your concrete and can crack...

Obviously, the steel box segments and cable pipes would have to be curved, making a comlete circle when assembled.
The whole point of prestressing concrete is to put it under compression, using tensioned steel cables, so that it can't crack.


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PostPosted: Apr 09, 2009 2:04 pm 
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jaro wrote:
STG wrote:
you would also be bending your steel structure which bends your concrete and can crack...

Obviously, the steel box segments and cable pipes would have to be curved, making a comlete circle when assembled.
The whole point of prestressing concrete is to put it under compression, using tensioned steel cables, so that it can't crack.


If you are interested, here is a complete description of the construction process. See chapter 7. Figure on page 105

http://www-pub.iaea.org/MTCD/publicatio ... 90_web.pdf

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PostPosted: Apr 09, 2009 2:55 pm 
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Thanks very much -- I will check it out.


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PostPosted: Apr 10, 2009 12:57 am 
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Steel plate construction has very large potential. It enables factory prefabrication, using computer aided manufacturing methods for cutting plates and welding very similar to those which have been perfected for ship building (the same factories can be used). Amazing tolerances can be held, and equipment can be directly mounted to prefabricated pads.

Steel plate reinforced concrete responds much better when driven past the elastic limit, since the plate keeps the concrete confined as it begins to fail and it can still carry compressive loads, while with conventional reinforcing bar the concrete spalls away.

AP-1000 switched to steel plate for the external events shell of its containment, which allowed it to accommodate aircraft crash without increasing the thickness of the containment wall. The other result was to cut over a month off of the AP-1000 construction schedule.

This technology is clearly the future direction for nuclear construction. It's interesting that the Koreans are pretty far ahead on this.


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PostPosted: Apr 10, 2009 2:32 am 
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Steel plates are initially shaped as formwork for concrete and then take over as reinforcement placed at the skin. Suitably placed lugs ensure continued bonding with concrete. steel structural components welded as spacers would take over as shear reinforcement. formwork does not have to be removed, saving effort and time.
Wherever the plates fall short of eventual requirement in the worst loaded condition, additional reinforcement can be welded.


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PostPosted: Apr 10, 2009 8:42 am 
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Axil wrote:
See chapter 7. Figure on page 105

Did you mean figure 7.3 on page 99 ? (there is no figure on p.105)

Unfortunately, no info on whether/how this could be applied to prestressed concrete structures, such as the RB dome.


PS. the steel plate technique is commonly used on large transfer flasks for radioactive materials: plates are connected by numerous "zee bars", the whole structure is pre-heated, and then lead is poured into the enclosed spaces..... Temporary external bracing may also be used, to prevent bulging of the steel plates under the "plumbostatic" load....


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PostPosted: Apr 10, 2009 12:39 pm 
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jaro wrote:
Axil wrote:
See chapter 7. Figure on page 105

Did you mean figure 7.3 on page 99 ? (there is no figure on p.105)

Unfortunately, no info on whether/how this could be applied to prestressed concrete structures, such as the RB dome.


PS. the steel plate technique is commonly used on large transfer flasks for radioactive materials: plates are connected by numerous "zee bars", the whole structure is pre-heated, and then lead is poured into the enclosed spaces..... Temporary external bracing may also be used, to prevent bulging of the steel plates under the "plumbostatic" load....


So very sorry to confuse you. I used the PDF page counter and not the document page number. I will try to do much better in the future. I will also work very hard to research the prestressed concrete structures next.

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PostPosted: Apr 13, 2009 12:47 am 
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An important point for LFTR/AHTR is that fluoride salts provide no stored energy source that can pressurize a containment (e.g., they are inherently low pressure (unlike water/helium) and have low chemical reactivity (unlike sodium)). They are separated from their power conversion system, which will have a high-pressure working fluid and stored energy, by a low-pressure intermediate loop. The power conversion turbine hall will be designed with blow-out panels to relieve pressure if a large break occurs in the power conversion system piping. Thus no need for pre-stressed concrete, and steel plate concrete construction is the correct approach to take for the reactor building, to reduce construction time and increase the fraction of work that can be done in a factory setting.


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PostPosted: Apr 13, 2009 7:36 am 
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Per Peterson wrote:
The power conversion turbine hall will be designed with blow-out panels to relieve pressure if a large break occurs in the power conversion system piping.

Yes, this is standard practice currently.
I had a close look at the blow-out panels in the turbine building at Gentilly-2 NGS, a few years ago: They're actually large sections of the building wall -- to open at very low overpressure, since the turbine building isn't built for taking overpressure, and could be blown appart otherwise.


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PostPosted: Jul 17, 2009 10:07 am 
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Hi

I've just been searching the web and I came across your forum.

We have been manufacturing a steel plate reinforced concrete system for construction for many years known as Bi-Steel.

Is this type of product of interest in the nuclear industry? We use it to contruct blast resistant structures and complete building cores.

Have a look at our web site and I would appreciate your views http://www.corusconstruction.com/en/abo ... and_build/

Regards

Jurek


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PostPosted: Jul 17, 2009 10:23 am 
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Welcome Jurek!


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