Monday, June 17, 2013

Nuclear Fusion or Thorium – Which is tomorrow’s energy?

It was announced back in March that India was considering using a Thorium based reactor instead of a Nuclear Fission reactor in their attempts to gain energy that was free of the standard dependence on oil or coal. Last year Norway began four years of testing of Thorium reactors. Additionally China has expressed interest in Thorium reactors. And there are many other countries are on that list. Who can blame them for running from Nuclear Fission? Three Mile Island, Chernobyl, Japan, countless dumps of nuclear waste with a half-life ranging from 6,560 to 24,100 years.

So how does Thorium work? Many Thorium reactors use fluoride salt. It is heated to where it melts. Then thorium fluoride is dissolved in the salt. The Thorium absorbs neutrons and turns into Uranium which then produces heat plus more neutrons through the Uranium-233 fissions. Because the fission products are short-lived this considered to be much safer than a traditional reactor. The reactor does not contain high pressure steam so it can not explode and Thorium is abundant and most of it is used up in the reaction.

What is Thorium? Thorium is a soft, ductile, silver-white, radioactive metal and is considered one of the rare-earth metals. Although pure, it is also stable and resists oxidation, reacts slowly with water, and is attacked only by HCL. The finely divided metal will readily ignite when heated but has one of the highest melting points. It is abundant in the earth’s crust and one of its chief sources is Monazite sand – a reddish-brown phosphate mineral containing rare earth metals, and located in India & Brazil. Low grade Thorium ore is also found in New Hampshire.

However, Thorium is also highly radioactive. Thorium waste also has a half-life of over 200,000 years thus having storage issues for the spent fuel. It is not cheaper to run as the fuel cycle is more costly and the numerous protections needed for the workers/plant safety are also quite expensive. The claim that it is so safe that it can be handled by your bare hands is both true and false. True, but you can also handle a Uranium pellet.

But are there any other options?

Let’s take a look at Nuclear Fusion. Nuclear Fusion is the opposite of Nuclear Fission. Fusion is just what it says, two atoms fusing to form one larger atom. Two hydrogen atoms are combined to form a helium atoms, neutrons and lots of energy. It is the same reaction as the Sun. There is more than one type of fusion reaction although most involve the isotopes of hydrogen called deuterium and tritium. France is right now constructing a Fusion Reactor called ITER which in Latin means a passage or tunnel – and that’s what they are hoping for, a passage to the future; one that doesn’t rely on oil for energy.

The fuel ITER will use? The Hydrogen isotopes deuterium & tritium were chosen and not just for their wide availability and hence low-cost, but also because the reactions do not have the radioactive waste as a legacy. Are there any safety concerns? No. There is no risk of a meltdown or runaway reaction. Should anything go wrong, the plasma cools itself automatically halting the process so while the fuel is heated to extremely high temperatures, should it expand to touch the wall, it instantly cools. Consider this, 2 liters of water and 250 grams of rock can provide enough energy for a family. MORE? Fusion is a clean energy source which results in NO greenhouse gases. Deuterium & Tritium are limitless.

The drawbacks? While it does not produce radioactive waste, the reactor remains radioactive for 100 years. Not bad when compared to the waste alone in Fission being radioactive for thousands of years. Also, the amount of energy required to power the reactor in order to obtain energy, is tremendous. Another drawback with fusion, there are many who say that Cold Fusion may be the only way to make Fusion efficient and thus far we have not successfully developed it.

Basically, when commercial scale fusion plants become a reality we will have an unlimited, nearly free, clean source of energy. Of course with the energy problem taken care of what on earth would we concentrate on? Climate Change? Poverty? Hmmm.

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