By Charles F. Moreira, Editor
Whilst China has invested much effort to increase its wind and solar electricity generation capacity as an alternative to reduce its current reliance on environmentally polluting coal-fired electricity generation, Enterprise Trade Views now looks at China’s nuclear energy initiatives.
According to the International Energy Agency’s World Energy Outlook 2017 report, China had a 1,625 GW total installed electrical power generation capacity in 2016, of which 58% was coal-fired, followed by hydropower (20%), wind (7%), solar-photovoltaic (5%), gas (4%) and nuclear (2%).
By 2040, this will have grown to 3,188 GW total generation capacity of which 32% would be coal-fired, solar-photovoltaic (22%), wind (18%), hydropower (15%), gas (7%) and nuclear (4%).
Whilst according to those figures, nuclear-generated electricity comprises a tiny proportion of primary energy sources for electricity generation, however China’s share of global investment in wind, solar-photovoltaic and nuclear stood at 28% respectively for each of these energy sources.
Right now, China’s nuclear reactors are uranium-fueled and according to a research report – Nuclear Power in China: An Analysis of the Current and Near‐Future Uranium Flows, by Dr. Qiang Yue, Jingke He, Dr. Laurence Stamford and Prof. Adisa Azapagic, first published on 25 August 2016, China’s installed capacity of nuclear power plants is expected to reach 58 GW by 2020, between 83.9 and 200 GW by 2030 and between 250 and 400 GW by 2050.
They researchers estimated that China consumed 19,126 tonnes of natural uranium over the period 2003 to 2012, of which between 33 and 58% was from domestic sources, whilst the rest was imported. Over this same period, these nuclear power plants generated 3,811 tonnes of nuclear waste which has to be safely stored for up to several years before it can be reprocessed to recover the remaining uranium and plutonium.
They estimated that China’s uranium consumption would ramp up to 14,426 tonnes per annum by 2020, around 75% of what was consumed over the 10-year period, which could result in China’s natural uranium resources running out by 2027, if China relied exclusively on domestic resources.
However, China is already looking beyond uranium and plutonium towards alternative nuclear fuels such as the hydrogen isotopes deuterium and tritium used in nuclear fusion reactors such as China’s Experimental Advanced Superconducting Tokamak (EAST) a.k.a. “artificial sun” in eastern Anhui province on the one hand and on the other hand, towards Thorium for nuclear fission reactors.
Hydrogen is the lightest element with a single positively charged proton as its nucleus (core) and a single negatively charged electron orbiting around it, whilst the hydrogen isotope deuterium additionally has a neutrally charged neutron in its nucleus as well, whilst the tritium has two neutrons in its nucleus in addition to the single proton.
Nuclear fusion works by compressing super-hot deuterium and tritium nuclei together so that two protons and two of the neutrons merge to form a helium nucleus, whilst freeing the third neutron along with the release of large amount of kinetic energy.
EAST made news in 2017 when it became the world’s first fusion reactor to sustain certain conditions necessary for nuclear fusion for longer than 100 seconds, and in November 2018 it achieved a best temperature of 100 million degrees C in its core plasma and an ion temperature of 50 million C, and it is the ion that generates energy in the device.
EAST is part of the International Thermonuclear Experimental Reactor (ITER) project, which seeks to prove the feasibility of fusion power.
Currently under construction in Provence in southern France, ITER which is estimated to cost 20 billion euros is an international project funded and run by the European Union, India, Japan, China, Russia, South Korea, and the United States, and it will incorporate parts developed at the EAST and other sites, and draw on their research findings.
Initially conceived in the Soviet Union in the 1950s by Soviet physicists Igor Tamm and Andrei Sakharov, the first working tokamak was developed by Soviet nuclear physicist Natan Aronovich Yavlinsky and began operation in 1958.
The doughnut-shaped tokamak uses coils which generate a powerful magnetic field to compress and contain the super-hot gaseous plasma from touching the sides of the reaction chamber which would otherwise melt or vapourise.
By the mid-1970s dozens of tokamak reactors were in operation in different countries around the world and by the late 1970s, tokamak reactors had met all the conditions required for nuclear fusion, though not all at the same time. With the goal of breakeven between energy input and output in sight, new series of tokamak reactors are designed to run on deuterium and tritium.
Deuterium is a virtually inexhausatble resource. It’s widely available and can be distilled from all forms of water. For instance, there’s 33 grammes of deuterium in every cubic metre of seawater and its deuterium is routinely produced for scientific and industrial applications.
On the other hand, tritium occurs only in trace quantities in nature but it can be produced during the fusion reaction through contact with lithium, such as when neutrons escaping the plasma interact with lithium contained in the blanket wall of the tokamak.
Lithium is easily extractable from proven land-based resources and is expected to be enough to operate fusion power plants for over 1,000 years. It can also be extracted from ocean water, where reserves are believed to be practically unlimited to fulfil the world’s energy needs for up to six million years.
However, EAST, ITER and other fusion reactors around the world are all still experimental and Wu Songtao, a top Chinese engineer with ITER, conceded that despite China’s achievements with EAST, however China’s technical capabilities in fusion still lag behind more developed countries such as the United States and Japanese where their versions of tokamak have achieved more valuable overall results.
Meanwhile, China aims to build a separate fusion reactor that could begin generating commercially viable fusion power by 2050 and the government has pledged some six billion yuan towards this project. However, that’s about 31 years down the road.
China’s government had originally given Chinese scientists until 2029 to develop the world’s first nuclear power plant fuel by thorium instead of uranium but following China’s Premier Li Keqiang statement to the national legislature in Beijing on 5 March 2014 that the government aimed to resolutely tackle the problem of pollution, including to close coal-fired power stations, this deadline was brought forward to 2024.
According to government figures, about 70% of China’s electricity was generated by coal-fired power stations in 2013, whilst nuclear power stations generated just over 1 per cent, which is minuscule compared to countries such as France which produces 75% of its electricity from nuclear plants, albeit uranium fuelled.
In response to this new directive, the Chinese Academy of Sciences set up an advanced research centre in Shanghai in January 2014 to develop the world’s first industrial reactor using thorium molten-salt technology, according to a statement from the academy’s Bureau of Major Research and Development Programmes, the South China Morning Post of 18 March 2014 reported.
Scientists in the United States had developed an experimental molten-salt fission reactor at the Oak Ridge National Laboratory in 1964 and it was operational until 1969.
Unlike fusion reactors, fission reactors are fuelled by amongst the heaviest elements such as uranium 235 which has 92 protons and 143 neutrons in its nucleus and fission is achieved by high-energy neutrons which hit the nucleus causing it to split into two and in some case three lighter elements with the release of large amounts of energy and more high-energy neutrons which go on to split more uranium nuclei. This is somewhat like how the white billiard ball hits a cluster of billiard balls causing the cluster to split, with the balls scattering across the table.
Also one of the heaviest elements, thorium has 90 protons and 142 neutrons in its nucleus, though thorium itself is not fissile – i.e. its nucleus does not split when hit by a neutron. Instead its nucleus absorbs the additional neutron to become thorium-233 and due to beta-decay, thorium-233 becomes protactinium-233 22 minutes later, which 27 days later, due to beta-decay, turns into uranium-233 which is fissile. In nuclear physics, this conversion process of thorium-232 to uranium-233 is called “breeding”.
The Oak Ridge experimental reactor was initially fuelled by uranium-235 to get it started but later was fuelled by uranium-233 bred from thorium-232. The fuel is dissolved in the molten salt, with the rate of nuclear reaction regulated by graphite rods in the reactor vessel.
One of the advantages of molten salt reactors over pressurised water reactors currently in use is their safety against explosion, since the former don’t need to be pressurised to prevent the molten salt from evaporating, whilst the latter can explode due to high steam pressure.
Moreover, additional fuel can be added to molten salt reactors whilst they are running, whilst waste removal can be ongoing.
Also, molten salt reactors are safer in the event of a power failure or any problem, since solidified salt plugs in the piping to salt storage tanks below will melt in event of loss of cooling power, resulting in the molten salt draining out of the reactor into the tanks and the fission process stops until the salt is reloaded into the reactor.
Another advantage is that thorium is less radioactive than uranium and the waste from molten salt reactors remains radioactive for a few hundred years, rather than tens of thousands of years with waste from uranium or plutonium reactors
However, U.S. president Richard Nixon shut down the Oak Ridge experimental reactor in 1972 in preference for uranium reactors, though countries such as China and the U.K. are now reviving molten salt reactors.
According to the South China Morning Post of 10 January 2019, a plan in China is to develop the world’s first large-scale thorium-powered, molten-salt reactors – which could generate less radioactive waste and help reduce China’s reliance on fossil fuels to reduce the world’s energy needs by 2020.
An advantage for China is that unlike uranium which it has to import, the country has large reserves of thorium, which also is a waste product of the processing or rare earths, which China has in abundance.
Another advantage of molten-salt reactors is that they do not need much water, so they can be built in remote desert regions far away from populated areas.
Work on two molten-salt reactors located in the Gobi Desert in Gansu province began in 2011. The 12-megawatt reactors were designed to show the viability of the technology and it is hoped they will be up and running by 2020.
According to Xu Hongjie, director of China’s molten-salt programme, China’s researchers and scientists have mastered the technology to produce key devices for molten salt reactors and own 202 patents on the technology. The programme is led by the Shanghai Institute of Applied Physics, part of the Chinese Academy of Sciences.
China has invested about 2 billion yuan in molten-salt research and development over the past several years, but building the plants is expected to require tens of billions more.