WHAT DO YOU think of when you hear the phrase ‘nuclear energy’? Maybe you think of Fukushima and Chernobyl. It could be the Cold War imagery of weapon tests that spring to mind for you. Or is it those giant cooling towers looming over the countryside? Maybe, like me, you see beyond the negatives and consider nuclear energy to be an opportunity.
I think nuclear energy gets a bad rap, largely because things like atomic weapons and power plant disasters are very often associated with it. But it’s not all bad, and thanks to modern understanding of nuclear physics and advancements in reactor technology, I believe it’s mostly good, and that nuclear energy could provide Ireland with a cheap, safe, and environmentally-friendly power source.
What is nuclear energy?
Waterford man, Trinity College Dublin staff member, and Nobel laureate Ernest Walton was, along with John Cockroft, the first person to artificially split the atom. He did so in April 1932 by bombarding lithium atoms with protons, which embedded themselves in the atomic nucleus making it unstable. The lithium atom then broke apart into two helium atoms, and some of the energy that held the lithium atom together is released.
Modern reactors will generally use uranium as the fissile material. When a uranium atom absorbs a neutron, it breaks apart into two daughter atoms – such as barium and krypton – and some more neutrons, which in turn can trigger further reactions.
Is it safe?
We usually default to shock and automatic disdain on the very mention of atomic energy; but why? Perhaps surprisingly, the number of deaths and illnesses caused by nuclear power plant incidents is relatively very low compared to cases resulting from traditional fuel power plants.
Obviously, an ideal situation would be zero risk and zero health effects, but this is impossible, no matter what type of power plant we’re talking about. So let’s put it in perspective: there were no direct deaths (immediate radiation exposure, etc.) following the Fukushima and Three Mile Island disasters, and 41 people died as a direct result of the accident at Chernobyl. In contrast, for every person that dies from nuclear power, about 5,000 die from coal and oil power.
Nuclear waste
Nuclear reactions produce by-products, many of which are hazardous. The main purpose of the first reactors was to produce energy, and this was at a time when nuclear waste wasn’t an issue. Waste from such reactors undergoes a treatment process to reduce the dangers as much as possible, and also to render the waste somewhat useless should it ever find its way into the wrong hands. Long-term storage of nuclear waste often includes burial of the material deep underground or under mountains.
None of this is ideal as it has inherent risks. The best solution would be to create a situation where no waste is produced or, failing that, where waste can be reused. This is the case with thorium-based nuclear power, which has fallen by the wayside due to the fact that it can’t be weaponised (remember, a lot of nuclear power research with uranium and plutonium was undertaken in an era where a superpower’s weapon arsenal was of paramount importance).
Thorium is changed into uranium inside the reactor, which is used as the main energy-producing fuel, and its by-product is material that can be used in further reactions. As well as this, it’s believed that thorium reactors will produce about 100 times less waste than current reactors and has a much shorter half life, meaning that overall the problem with nuclear waste treatment and disposal is greatly reduced.
Reactor types
There are 435 power-generating fission reactors in the world today, with a further 75 under construction. There are different types of reactors, and most are designed to last several decades. The Soviet-developed reactors at Chernobyl were of the Generation II family (which last 30-40 years) and all at that site have since been shut down.
Generation III reactors are more modern reactors, built from the 1990s onwards, with improved efficiency and passive safety features, and there are about a dozen of these in operation around the world.
The next step will be the production of Generation IV reactors. These have the ability to actually reuse what would be otherwise useless spent nuclear fuel, meaning a vast reduction in waste. Coupled with this, the leftover spent fuel from Gen IV reactors will have half lives of hundreds of years, unlike current by-products from current reactors, with half lives of tens of thousands of years. (Some reaction by-products actually have half lives of millions of years, but the radioactivity is so weak that it’s even less than that of natural background radiation.)
Nuclear fission v nuclear fusion
A major aim for modern nuclear physics is the development of a fusion reactor that can sustain reactions continuously. Man-made nuclear fusion already exists (with a few hundred euro and some time you can build yourself a tabletop Farnsworth-Hirsch reactor), but the problem is that it requires a lot of input energy to sustain the reactions and the process produces less energy than what goes in, unlike in nuclear fission. The goal is to develop a reactor that can continuously produce more energy than it requires to function, so that the excess energy can be given to energy and electrical grids to give us power in our homes. The development of ITER in France will hopefully work towards making this a reality.
Fusion reactions in and of themselves are “clean”, in that the reaction does not produce nor necessarily use radioactive material. This effectively stops the production of nuclear waste that occurs in current fission reactors. However, a fusion reaction does produce fast-moving neutrons that escape from the resulting atom. These neutrons can interact with material in the walls of the reactor or in the building to make them radioactive, and a fusion core at the end of its lifetime could be just as radioactive as a fission core. However, the types isotopes that result from fusion reactors mean the core is hazardous for about 50 years, whereas a fission reactor core can be hazardous for thousands of years.
Ireland’s option
Most reactor cores produce in or around 1,000 MW of power. Poolbeg has a capacity of 463 MW, around half a single core, or about a quarter of the capacity of just one two-reactor nuclear power station. Indeed, with one such station, we could potentially replace the entire power output of Ireland’s five largest power plants at Poolbeg, Whitegate, Aghada, Dublin Bay, and Huntstown.
It’s probably clear to you by now that replacing several generators with one nuclear station not only reduces the environmental and human impact, but also results in lower maintenance and running costs, with savings potentially passed on to the customer.
In 2012, we used 154 TWh of energy. A single two-reactor nuclear power plant would supply 17.5 TWh in a year, almost reaching the same amount of energy generated by all of Ireland’s currently operating power plants (21 TWh). Nine two-core nuclear power plants would power the country completely, though such a construction project would likely be a bit impractical. However, a four-core plant would cater for about a fifth of the country’s energy requirements.
Of course, there may not be a need to go with such high capacity reactors for Ireland. Currently in development are small reactors with capacities of about 300-700 MW. One such reactor is IRIS, which has a capacity of 335 MW, but can be modified to be as low as 100 MW. It is specially designed to be much safer than current reactors, particularly in accidents. A small handful of IRIS power plants across the country could be ideal for Ireland.
While they’re not available yet, I feel that small thorium reactors would be an ideal setup for Ireland. Thorium is very abundant and only very slightly radioactive, meaning vastly reduced fuel costs and much less waste disposal issues. There is virtually no risk of a core meltdown, as the cycle in thorium reactors is not self-sustaining: once the external neutron source is powered off the reaction stops. Thorium reactors are a completely different type than the current reactors that were borne of Cold War era research, and their designs lend themselves to being much safer and efficient overall.
More fossil-fuel plants? That’s not the answer
In the meantime, however, small modular reactors may be the best fit for Ireland at the moment. These reactors are newly developed with better designs taking into account various safety features. They are small so can be built quickly and cheaply and, if needed, several of them can be coupled together to generate more energy.
In conclusion, we need to look at nuclear energy as a potential power source. Our population is increasing, but building more and more fossil-fuel plants to cater for this will only result in more and more pollution with unnecessarily high operating costs. We should also reduce our dependence on importing energy from abroad, as such costs will keep increasing as oil prices continue to go up. The pros to going nuclear far outweigh the cons, and the overall net benefit is is much greater than staying with burning fossil fuels to generate energy.
Conor Farrell is an avid science enthusiast and studied physics with astronomy at Dublin City University. He has worked at Astronomy Ireland and Dunsink Observatory in the past, and loves to promote all things space-related to a wider audience. In his spare time he writes about science and current affairs, and can be followed on Twitter at @conorsthoughts.
Read more articles by Conor Farrell.
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