News on China's scientific and technological development.

Hendrik_2000

Lieutenant General
I wonder why they selected helium as the heat transfer medium?
Although helium is inert making it a very stable gas even at very high temperature it's also a very light gas next to hydrogen making it an inefficient medium to transfer energy.

That is true but because it generate high temperature overall it will produce high efficiency up to 50% which is unheard of. The conventional power plant has very low efficiency around 30% and relatively low temperature producing wet steam(saturated steam) necessitating very large steam turbine .

But the main reason why helium is selected is because it doesn't absorb contaminant and more important it doesn't absorb neutron so it doesn't become radioactive itself . So in theory you can use it to drive turbine . But in reality and regulatory requirement. You need to pass it to heat exchanger (Steam generator) to generate steam that drive the turbine.

This type of reactor is attractive because it is the only one that has negative loop and prevent run away reaction like in Fukushima
It does so because so called Doppler broadening
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When the
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increases in temperature, the rapid motion of the atoms in the fuel causes an effect known as
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. The fuel then sees a wider range of relative neutron speeds.
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, which forms the bulk of the uranium in the reactor, is much more likely to absorb fast or epithermal neutrons at higher temperatures. This reduces the number of neutrons available to cause fission, and reduces the power of the reactor. Doppler broadening therefore creates a negative feedback because as fuel temperature increases, reactor power decreases. All reactors have reactivity feedback mechanisms, but the pebble-bed reactor is designed so that this effect is very strong. Also, it is automatic and does not depend on any kind of machinery or moving parts. If the rate of fission increases, temperature will increase and Doppler broadening will occur, decreasing the rate of fission. This creates passive cooling.

Another attractive feature is it doesn't use water as the primary coolant which eliminate a lot of the complicated high pressure cooling system and safety shutdown system with their attendance of complicated control system that need powered control valve

That is exactly what went wrong in Fukushima when the valve of the safety shut down system cannot be open because the electrical system is located in the basement and flooded by water.Causing run away reaction.

This type of reactor can also use Thorium as fuel the most plentiful on earth

The German are the pioneer of this type of reactor But they abandoned it because of accident caused by human failure and the general aversion of anything nuclear after Chernobyl. The Chinese license some of their system and buy the fuel

The Chinese claim they solved the problem in their 10 MW pilot plant and improve on the German design.
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This design would make and excellent Nuclear Submarine power plant because of their simplicity and safety. It doesn't need need noisy high pressure pump all you need is low pressure circulating compressor
.
They already have 10 MW design all they need is double it and make it more compact
 
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Equation

Lieutenant General
The thing is whether China would share the latest technology with ITER to crack it ... ITER has had some issues for a while and China may just leave it like the USA says they would. It seems ITER is just too complicated.
from Wiki
"Construction of the ITER Tokamak complex started in 2013 and the building costs are now over US$14 billion as of June 2015, some 3 times the original figure.[7] The facility is expected to finish its construction phase in 2019 and will start commissioning the reactor that same year and initiate plasma experiments in 2020 with full deuterium–tritium fusion experiments starting in 2027"

so ITER (if everything goes smoothly) will initiate plasma experiment in 2020, while China, the USA and Germany have started and somewhat successfully years ago. And building cost US$14B ... gooosh

My question: what would happen when the goal is achieved (100 million °C for 1,000 seconds ??? ... I believe it will be achieved before 2020

Like ITER would share anything with anybody much less with China.
 

SamuraiBlue

Captain
The fuel then sees a wider range of relative neutron speeds.
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, which forms the bulk of the uranium in the reactor, is much more likely to absorb fast or epithermal neutrons at higher temperatures. This reduces the number of neutrons available to cause fission, and reduces the power of the reactor.

So it's basically a fast breeder type reactor to create Plutonium when using Uranium. It may become a obstacle if PRC is wanting to export the technology until usage of Thorium as fuel is proven and technology to prevent Uranium as fuel is realized.
As for water being used whether it being pressured water type or boiling water type, water as energy transfer medium is efficient due to it's unit weight. A large turbine means it can generate more electricity which is better economically.
 

AndrewS

Brigadier
Registered Member
AlphaGo on a smartphone? Chinese brothers plan to put AI in your pocket with start-up based on Cambrian deep-learning processor


Two scientists from Chinese Academy of Sciences expect Cambrian to beat smartphone vendor Xiaomi’s record valuation of US$45 billion, aim to change the world by commercialising new AI technology
...
A team of researchers at the Chinese Academy of Sciences expect to set a new valuation record in China with their start-up based on Cambrian, a deep-learning processor they invented that may take artificial intelligence to the next level.
...
A paper they submitted to the ACM/IEEE International Symposium on Computer Architecture in Seoul this summer was given the highest score by peer-reviews among nearly 300 works submitted to the world’s biggest academic conference on computer chips.
...
“Their chip and new set of instructions [DianNaoYu] is completely different from anything we have seen before,” he said.

“If the technology works, it will start a revolution,” he added.


Read more
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This will be very interesting indeed.
 

TerraN_EmpirE

Tyrant King
China Plans First Commercial Rocket-Launch Company, Xinhua Says

Bloomberg News
March 15, 2016 — 3:17 AM EDT

China plans to set up a commercial rocket-launch company in view of the market’s potential, the official Xinhua news agency reported.

China Sanjiang Space Group Co. is preparing to enter the commercial-rocket business with a launch slated for 2017, Xinhua reported Tuesday,
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the company’s chief engineer Hu Shengyun. Some Internet companies have expressed interest in collaborating on commercial launches, Hu said.

The Kuaizhou-11, translated as “fast vessel,” rocket is being developed by the Fourth Academy of China Aerospace Science & Industry Corp., a major missile supplier to the People’s Liberation Army,
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China Daily.


China, India and other Asian countries are spending billions of dollars on their space exploration projects. Asian growth is set to increase competition for commercial rocket-launching companies such as Arianespace as countries invest more to develop their own technology to launch satellites and spacecraft.
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plawolf

Lieutenant General
Skynet on your smartphone...I suppose it's better if AI achieves self awareness before the militaries of the world outsources the business of killing people entirely to drones and combat robots, and I think most of the world's nuclear forces are still using equipment too antiquated to be easily compromised by evil AI (the US nuclear forces are still using computers running on LP sized floppy disks!).

Better that the worst Skynet could do hijack your Facebook status updates and give you wiseass replies when you ask your smartphone stupid questions and couldn't send a terminator after you as punishment for forgetting to fully charge your phone overnight or tripping that new Google nerd-bot.
 
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