Thorium can be found quite easily around the world – it is four times more abundant than Uranium – which is the choice for power generation from nuclear energy. We have always had the choice, but just before the Second World War, politicians chose Uranium because of the useful weapon by-product, plutonium which can be used for making the biggest bombs! And depleted Uranium can be used for tips on ammunition as it is very hard. So, clean, safe, sustainable Thorium was neglected. Luckily, experimental Thorium power was first developed by the US Navy for Submarines. Then the US Air force had to have one for their long range bombers! But, on second thoughts, that was a really, really bad idea. But the principle of power generation using Thorium had been proven and tested, so the idea was taken further by the Oak Ridge National Laboratory in Tennessee, who successfully built a Thorium “Molten Salt Research Reactor” that ran for five years producing power in the 1960’s.
The whole power unit is very small; the biggest part is the working chamber column, some 18 feet tall and at its biggest, six feet in diameter. And it is not complicated like a modern aircraft or even a car, having few moving parts! Because it works at around 7- 800o C it is very efficient, and can drive an energy turbine which is quite small, too – as small as a desk! It is a compact power plant giving off enormous heat all derived from easily obtained fuel!
The Next Great Energy Market
Because of environment issues, it has become a very interesting business proposition to many countries around the world, China and India in particular. Many countries see it as a great answer to the world’s energy problems and are racing to develop and market it all around the world. It’s energy output can be applied to so many uses – it is sure to be a ‘hot seller’ once it is developed and has the necessary safety approvals. There is a quiet race on, to get it market- able. It is small, comes in modules or units, and is expected to be inexpensive. It can produce vast quantities of electricity with no dangerous end products and … it’s end applications naturally, create jobs.
Research and development has to continue for the present. There are no corrosion problems say its supporters, with the nickel super stainless steel but they admit to problems keeping valves serviceable at those high temperatures.
There is no pressure containment problem as it runs at atmospheric pressures. It has “walk away” safety: it has to be stimulated to keep it going, quite the opposite to ‘run away’ Uranium power generation. Storage of Thorium presents no problems as it can be just piled high in bins or storage areas. It can’t react by itself, but needs to be triggered by a neutron source.
Low radiation
Thorium is a low-level Alpha transmitter with a 12.5 Billion year half – life. Therefore, the sodium in bananas emits more radiation and can be said to be more dangerous. The ash from coal fired generation is more radioactive and so, more dangerous. Thorium is not water soluable and cannot be metabolized – absorbed by the human body. It has 6 million times more energy than coal per unit. This mineral is mined along with other rare earths and sands and so, comes free.
Surely, here is an opportunity of working with the big powers in research and developing this in Sri Lanka – It means high quality JOBS!
Chemical Thorium – a Metal with a half-life of the Universe!
It is the chemical element with symbol ‘Th’ and atomic number 90. It is a radioactive actinide metal. Thorium is one of only two significantly radioactive elements that still occur in nature in large quantities as a primordial element – the other being Uranium.
A Thorium atom has 90 protons and therefore 90 electrons, of which 4 are valent electrons. Thorium is a silvery metal which tarnishes to black when exposed to air, forming the di-oxide. Thorium is weakly radioactive all its known isotopes are unstable. Thorium has a half life of 14.o5 Bn years, or about that of the age of the Universe: it naturally decays slowly.
It is refined chiefly from Monazite sands, as a by-product of extracting rare-earth metals. At room temperatures Thorium has a face-centred cubic crystal structure – and the usual major impurity is Thorium Di-oxide. The melting point is 17500C – above Actinium (12270C) and Protactinium (15600C)
Thorium can form alloys with many other metals and is known to improve the strength of weak Magnesium.
Types of Thorium -based Reactors
According to the World Nuclear Association there are seven types of reactors that can be designed to use Thorium as a nuclear fuel. The first five listed have entered operational service at some in the recent past:
1) Heavy Water Reactors (PHWRs)
2) Hi Temperature Gas-cooled reactors
3) Boiling (light) water reactors (BWRs)
4) Pressure (light) water reactors (PWRs)
5) Fast Neutron reactors (FNRs)
6) Molten Salt Reactor (MSR, LFTRs)
– Oak Ridge National Laboratory demonstrated MSR from 1965 -69.
7) Accelerator Driven Reactor (ADRs)
8) Aqueous Homogeneous Reactors have also been built and seven are in operation as research reactors.
Unlike natural Uranium, natural Thorium contains only trace elements of fissionable material (such as 231Th) which are insufficient to initiate a nuclear chain reaction, so additional fissile material or a neutron source is necessary to initiate the fuel cycle.
The Future
Progressive intellectuals think Thorium is extremely important for the next step of cleaner, safer nuclear power generation. Georgia Institute of Technology in the US, say Thorium-based power can mean a 1000 years solution or a high quality means of reaching a truly sustainable energy future, solving a huge portion of mankind’s problem of negative environmental damage. They say, small prototype plants should be built.
China, India, Norway, Israel and Russia (where Sri Lanka??) are doing this research by building Primary Liquid Fluoride Thorium reactors (LFTRs) – a molten salt reactor. India has the largest supplies of Thorium in the world. The Bhabha Atomic Research Centre (BARC) plans to make India Energy independent by 2050 .
Sri Lanka needs specialists to study this important energy source of Thorium.
RO.Smith, 27/12/2016