April 06, 2011 09:44
China is becoming a kind of nursery for unproven or rejected nuclear reactor technology. Nuclear plant designs that have failed to pass standards in other countries are being transformed into new models and incorporated into Chinese construction plans, but safety concerns are growing.
One example is the 18 pebble-bed nuclear reactors or PBRs China plans to build in Shandong Province in the eastern part of the country. These reactors are fueled by graphite spheres embedded with small uranium pellets and piled up inside to cause nuclear fission. Helium gas is heated as it passes through the spheres, heating water into steam, which in turn power turbines to generate electricity.
The advantage is that helium transfers more heat than water and is therefore more efficient, but no other country in the world uses the technology since graphite can burst into flames when it comes into contact with water. Germany built a 300 MW PBR nuclear plant in 1983 but voluntarily shut it down a few years later because it was unable to overcome the safety problems. It was graphite powder that was responsible for spreading radioactive matter across Europe during the Chernobyl disaster. Hwang Il-soon, a nuclear scientist at Seoul National University, said if the structure is solidly built there is no risk of fires, but the question is whether China has reached this level of technology.
Another design China is pursuing is the sodium-cooled fast reactor or SFR. Many experts are concerned about this development since SFRs use liquid sodium as a coolant. The U.S., France, Russia and Japan attempted to build SFR nuclear plants but failed. The biggest drawback is that sodium is extremely flammable if it comes into contact with water or air. A fire broke out at Japan's Monju SFR shortly after it opened in 1995 and it had to be shut down for 15 years. At present, Russia is the only country to operate an SFR plant, which has suffered 14 fires since it began operations in 1980.
China plans to construct an upgraded version of Russia's BN-600 reactor boasting 10 percent more efficiency in Fujian Province starting this August.
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