Graphite for Nuclear Power: The 2011 Japanese ear
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Posted On: 01/12/2014 3:34:40 PM
Graphite for Nuclear Power: The 2011 Japanese earthquake/tsunami and subsequent radiation at the Fukushima power plant raised serious questions about current methods of generation of nuclear power. Despite this and contrary to popular opinion, it is likely that the use of nuclear power in the world will grow significantly by the end of this decade. Nuclear reactors built half a century ago are a far cry from the more efficient and safer reactors being designed today. From a worldwide perspective, of particular importance is the large scale increase in demand for power in China, India and elsewhere in Asia – countries which house more than half the world’s population, have limited accessible oil resources and which consume only a small percentage of energy per capita compared to the industrialized countries of the west. Meanwhile, worldwide concerns about carbon emissions due to fossil fuels are just as strong as concerns about nuclear power. What is little understood about nuclear power is that current technologies are quite different and radically improved from the methods of the past. Of particular interest in this (graphite) context is the Pebble Bed Nuclear Reactor (PBNR), which is a small scale reactor which uses an inert gas rather than water as a coolant. It is thus not dependent on the large-scale supply of river/lake/tidal water that characterizes all prior generations of nuclear reactor. Also, the nuclear fuel in a PBNR is embedded in hundreds of thousands of balls of Graphite, as shown below: An October 2011 National Geographic on “Meltdown-Proof Nukes” article explains:? A pebble-bed reactor is made up of about 400,000 pebbles. Heat from the fuel spheres is picked up by helium and can then be used to generate electricity—or to drive industrial processes such as oil refining and desalination.? Blowers move helium gas through the reactor and over the pebbles, where nuclear fission releases large amounts of energy, heating up the helium.? About 5,000 spheres move through the reactor each day, like gum balls through a vending machine. The constant circulation means no refueling interruptions.? If a pebble taken from the bottom can produce more power, it goes back in the top. If it’s spent, it’s stored as waste, and a new pebble is added. What this article did not explain is that each “pebble” is about the size of a tennis ball and contains about 200 gm (almost half a pound) of Graphite surrounding a very small amount of nuclear fuel. Once “spent”, the entire pebble will be stored as nuclear waste. i.e., more than 90% of the material consumed in a PBNR is Graphite. And this is not just some theoretical idea. By 2004 China was operating a 10MW PBNR (the HTR-10 – or 10MW High Temperature Reactor) at its prestigious Tsinghua University, using 27,000 fuel pebbles. (Source: “Wired”). Two prototype 200MW versions of this pebble bed reactor are under construction and due to be commissioned by 2014. A total of 18 PBNRs are planned for Shandong Province alone by 2020. Small scale modular nuclear reactors such as these can be used to fuel specific industrial operations in remote locations or to cover the power needs of small to medium size communities. It is reported that companies such as Hitachi are developing turnkey solutions using PBNRs to meet just this type of need. Chinese leadership in the use of PBNRs could lead to broad acceptance of this technology in North America, with massive implications on the demand for Graphite.
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