Future tech

How China hopes to solve nuclear waste issue with hybrid fusion-fission reactor at top secret facility

PUBLISHED : Friday, 17 July, 2015, 8:00am
UPDATED : Saturday, 18 July, 2015, 2:32am

China will build a new hybrid reactor that can burn nuclear waste via a combined fusion-fission method by 2030.

This could give a potentially dramatic boost to China's attempt to switch to more environmentally friendly energy production methods, by recycling the waste produced by traditional nuclear plants into more electricity.

Traditional nuclear power plants produce large amounts of waste, the primary component in which is uranium-238, which cannot be used by current fissile-based reactors. The proposed hybrid reactor will use nuclear fusion to burn u-238 and could in theory recycle the waste from traditional reactors into new fuel.

The project is being developed at the Chinese Academy of Engineering Physics in Sichuan, a top secret military research facility where China's nuclear weapons are developed.

The scheme was first reported by the Science and Technology Daily, a newspaper run by the official Ministry of Science and Technology.

A viable fusion reactor is nowhere in sight, not to mention a hybrid. It's like talking about hybrid cars before the internal combustion engine was invented. 
Tsinghua University scientist 

Fission, which occurs in all commercial reactors nowadays, splits an atom in half, while fusion merges two atoms in one.

Both processes can release enormous amounts of energy, but neither method is perfect. Fission can generate large amounts of radioactive waste, while fusion requires a tremendous amount of energy to get going and control.

China is not the only nation engaging in fusion-fission hybrids. The idea to combine nuclear fusion and fission in one reactor had been around for at least half a century. Relevant research has been carried out in Russia, European countries, the United States and Japan.

But China is currently the only country with a clear schedule to build a hybrid reactor.

The plan is part of Beijing's ambitious campaign to replace dirty fuels such as coal with cleaner energy sources. Currently 24 reactors are under construction in mainland China, adding to 26 already in operation and many more in the planning stage.

Due to the lacking of recycling plants, most of the waste they produce is stored on site inside the plants, which increases operational and environmental risks.

The hybrid reactor could also relieve China’s uranium shortages. Due to their low quality reserves, uranium mines in China can only meet the demand for China’s nuclear industry for a century, but if the hybrid was built, China would have no need to import uranium for several thousand years, according to the report.

At the core of the proposed hybrid plant is a fusion reactor which is powered by electric currents as strong as 60 trillion amps. The reactor will be blanketed by a fission shell stuffed with uranium-238.

Such a design has numerous advantages. The high-speed neutrons generated by fusion could split apart the u-238 atoms to generate fission, and the fission could generate lots of energy to help maintain the fusion, thus significantly reducing the amount of external energy input, and achieve the complete burning of nuclear fuel to avoid radioactive waste.

Professor Wang Hongwen, deputy director of the hybrid reactor project, said that the key components will be built and tested around 2020, with an experimental reactor due to be finished by 2030.

The team said the proposed hybrid reactor could generate three times the power of a current fission reactor, while being safer as both fusion and fission reactions could be stopped immediately by cutting off external power, so disasters are less likely.

Some scientists warned that the timeline may be too ambitious however.

“A viable fusion reactor is nowhere in sight, not to mention a hybrid,” said a physicist with Tsinghua University, who declined to be named due to the sensitivity of the issue.

“It’s like talking about hybrid cars before the internal combustion engine was even invented. We will be lucky to have the first fusion reactor in 50 years. I don’t think a hybrid can be built way before that.”

Others are more optimistic about the technology. Professor Evgeny Velikhov, the "godfather" of modern fusion reactor design, has long been an advocate of the hybrid approach.

A hybrid reactor could be easier to build partly because it requires only a fifth of the external energy input of a “pure fusion” reactor to maintain operation, he said in 2012 during a visit to the International Thermonuclear Experiment Reactor project in France.