China Plans Radical Nuclear Reactor

srirangan

Banned Member
http://dsc.discovery.com/news/afp/20050207/chinanuke.html

Feb. 8, 2005
— China plans to develop a revolutionary, "pebble-bed" nuclear reactor that would be both meltdown and proliferation proof, and come on line in five years time, the Financial Times reported Tuesday.


A Chinese energy consortium has chosen the city of Weihai in northeastern Shandong province to build the 195-megawatt gas-cooled power plant, the newspaper said, citing an unnamed official representing the consortium.

The plant would be the first radically new reactor design for decades, putting China at the forefront in nuclear energy research that offers a "meltdown-proof" alternative to conventional nuclear power stations, it said.


"Pebble bed" reactors are fueled by thousands of small graphite balls with minute uranium cores which provide the fuel for the nuclear reaction.

The consortium includes electricity producer Huaneng Power International Inc, Beijing's Tsinghua University and China Nuclear Engineering and Construction, the Financial Times said.

No one from the companies was available for comment Tuesday.

Supporters say the technology is safer in terms of nuclear proliferation due to the expense and difficulty of processing the spent fuel from the graphite balls, the report said.

Advocates of pebble bed reactors also argue they offer cheaper, safer and easily expandable nuclear power stations. That appeals to China, which is struggling to meet huge growth in energy demand while avoiding environmental disaster.

"Pebble bed" technology was pioneered in Germany, which shut down its last prototype reactor in 1989, while a South African project remains in doubt, the newspaper said.
 
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highsea

New Member
PBMR's are a fairly new type of power reactors. The basic design dates back to the 50's, so I wouldn't really call them "radical". They just haven't been in common use yet, as there were fuel issues that needed to be sorted out. Modern ceramic technologies have overcome the problems, so they will become more common in the future.

They use uranium oxides encapsulated in graphite for fuel. They are high temperature reactors and use inert gases for cooling, usually helium. PBMR's are inherently safer that water cooled reactors, because they can operate at higher temperatures. The fuel absorbs more neutrons as the temperature goes up, so they can be designed to be self moderating if the coolant flow is interrupted, by making the reactor vessel lose more heat than is generated. So they can be made "meltdown-proof". If the coolant is interrupted, the reactor will cool down to idle temperature without operator intervention.

Helium has a low neutron cross section, so the coolant does not become as radioactive as water does. This permits the elimination of heat exchangers, since the coolant can run the turbines directly. It also eliminates the risk of steam explosions. Excess heat can be used to crack steam and generate hydrogen as a secondary energy source. They can also use lower enriched uranium as fuel, even natural and depleted uranium, which means that there is less fissionable uranium floating around. They can be continuously refueled without shutting down, and they are more fuel efficient than light water reactors. The spent fuel is very difficult to reprocess, which makes them safer from a proliferation perspective.

The designs are modular, so they can be mass produced. When more power is needed, you just add reactors. There is no need to design huge reactors when a bunch of small and (relatively) cheap reactors will do the same thing. China has plans for about 30 PBMR's by 2020.
 
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highsea

New Member
There are several different versions of PBMR's in R&D in the US. MIT, General Atomics, and Adams all have programs in operation, but for the most part, the US has abandoned High Temperature Reactors. PBMR's are not the only design, there are also designs using composite fuel rods. The US built a HTR of this type back in the 50's, and ran it for several years, so did Germany.

Right now, there are no facilities in the world to manufacture the fuel on a commercial scale. This is one of the bug hurdles with PBMR's because the pellets have to be perfect. The MIT reactor uses 360,000 pellets in the core, and discards about 350 every day. South Africa is developing a PBMR program also, and a new fuel manufacturing facility will have to be built to support it. Obviously China will have to do this also.

Containment of the uranium is done by the graphite/silicon shell of the pellet. If the shell fails, you can have a radiation leak. This happened in Germany when a pellet got stuck in the feed mechanism, and the German gov't shut down the plant because of it. PBMR's don't use containment buildings like PWR's do, they rely on the integtrity of the pellet. This is what gives the design it's modularity. Critics say that this makes the design too risky, since you can't guarantee 100% perfection in the fuel manufacturing process.
 

kashifshahzad

Banned Member
:coffee When there is a need for power generation like electricity any country must build resources whether it is a dam or a nuclear reactor to have cheap power:coffee
 

srirangan

Banned Member
  • Thread Starter Thread Starter
  • #8
kashifshahzad said:
:coffee When there is a need for power generation like electricity any country must build resources whether it is a dam or a nuclear reactor to have cheap power:coffee
I'll quote you on this :p
 
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