By Tom Gilsenan
School of Chemical Engineering
University of Birmingham

Nuclear power is the use of nuclear reactions to generate electricity. Nuclear power is considered a low-carbon source of energy and currently makes up roughly fifteen per cent of the energy used in the UK¹.

As we transition away from fossil fuels towards net zero, the need for a cheap, reliable and clean source of energy is becoming an increasingly important issue. In this article, the role of nuclear power in the future of the electricity grid will be discussed.

How Can the UK Achieve Net Zero?

Currently, nuclear power makes up about 15% of the electricity used in the UK. Renewable energy such as wind and solar makes up about 40%, and fossil fuels such as gas and coal now make up well below half of the energy mix in the UK¹.

The cheapest and most environmentally friendly option is to simply use less energy. Reductions in energy consumption reduce the amount of fossil fuels we need to burn to meet demand. Energy consumption per capita in the UK has generally decreased since 2005². This has been driven by increased energy efficiency in our cars and homes as well as more efficient (and some outsourced) manufacturing.

It’s important to note that although gas should not be used in the long term, it’s an important intermediary between really dirty fuels (such as coal) and zero carbon energy. Reducing our energy consumption will reduce the amount of gas that we need to burn.

However, unless we decide that we want to live in the dark without technology or transport, we will still need to use some energy. This is where renewables come in. Renewables already make up a large chunk of the electricity we use in the UK, with wind power making up the largest share.

So, the answer is to keep building more renewables until we can meet demand without fossil fuels?

Well, no. Renewables are great, but they’re also unreliable. In the winter, solar panels generate about 50% of the energy that they generate in summer, mostly due to shorter days. Similarly, on less windy days, wind farms drop in production. If that wasn’t bad enough, the amount of power generated by renewables can vary by minute, day or month.

In an electricity grid, the amount of energy generated must match the amount of energy consumed. If supply is irregular and hard to predict, it makes it harder to balance generation and use. There are ways we can store energy, such as pumped storage. We could effectively ‘store’ power through the generation of hydrogen gas, which can then be transported and burned. However, the amount of available storage could not currently support a fully renewable grid. New methods of storage are currently being developed, but cheap, large-scale storage has yet to be developed.

This means that for now, we will have to make do with a partially renewable grid. Without sufficient renewable generation or storage, we need to look to other sources of generation. It must be safe, reliable, low-carbon and ideally cheap (or at least no more expensive than current power). This leads us to nuclear power.

Nuclear power isn’t safe, is it?

A common misconception about nuclear power is that it’s not safe. Due to high-profile nuclear disasters such as Chernobyl and Fukushima, as well as paranoia about nuclear bombs and radioactive waste, nuclear power is perceived by many to be unsafe. The reality is that nuclear power is safer than any fossil fuel power on almost all measures³.

Deaths caused by nuclear power are often violent and dramatic and are covered extensively by news organisations as a result. However, many more ‘silent’ deaths are caused by fossil fuels. Firstly, the burning of fossil fuels releases particles into the air which, when inhaled, can cause respiratory illnesses and death⁴. People exposed to oil spills report a range of symptoms including fatigue, respiratory systems and psychological disorders⁵. Finally, the climate change caused by the burning of fossil fuels will lead to a catastrophic amount of death in the coming years if not mitigated now⁶.

On the safety of nuclear power, nuclear reactors cannot explode in the way a nuclear bomb does. This is because the fuel used in nuclear reactors is not as enriched as in a nuclear bomb. Enrichment is the process of increasing the concentration of the more fissile (easier to split) isotope of uranium. In a nuclear reactor, the concentration of the fissile isotope of uranium is not high enough to cause a nuclear explosion⁷.

The safety of nuclear power is improving constantly. Newer designs feature more inherent safety features and better operating procedures. We have learnt from the mistakes of the past and implemented stricter regulations and operating procedures designed to greatly reduce the risk of catastrophic failures. In my opinion, nuclear power can be considered as safe.

Despite this, we cannot ignore the waste produced by nuclear power. Currently, most nuclear waste is put into special containers and buried underground. Some of it is reprocessed and used for other purposes. The storage of waste mustn’t affect local groundwater or ecosystems. Another issue is ensuring that future generations know that our nuclear waste storage is dangerous, even if they don’t possess the knowledge that we have.

We’ve established that nuclear power is safe, but is it reliable?

Nuclear power is generally accepted to be one of the most reliable forms of power. For starters, nuclear reactors typically operate at a high percentage of their total capacity. This makes nuclear power ideal as a baseload. The baseload is the minimum energy demand over a given amount of time. The high capacity of nuclear reactors is in part because nuclear reactors only need to be refuelled once every 12 to 18 months⁸, and maintenance can be carried out during refuelling, cutting down the amount of time that the reactor is not producing power.

Additionally, nuclear power stations have long life spans. New power stations being built in the UK are predicted to last 60 years⁹. Since nuclear power stations are expensive to build, a longer lifespan allows for the cost of construction to be recouped over a longer time, reducing the effective cost of the power station. A long lifespan also gives policy makers time to plan for the future of electricity generation.

But is nuclear power low-carbon?

The short answer is yes. The nuclear reactions used to power the plant do not produce any carbon emissions, unlike other forms of power.

However, there are still carbon emissions to be considered. The emissions associated with the materials used to construct the power station are attributed to the power station, as are the emissions released during the extraction and enrichment of the uranium used in the reactors. We must also consider the emissions released when decommissioning (dismantling) the power station.

Despite this, the carbon emissions are still low in comparison to most other forms of power. The emissions of a nuclear power station are similar to those of a wind farm per unit of electricity produced¹⁰.

One issue, cost…

So far, so good. We’ve established that nuclear power is safe, reliable and has minimal carbon emissions associated with it. But what’s the catch?

The catch is cost.

There are two main types of costs that we need to consider:

• The capital cost of a power plant is the amount of money needed to design and build the power plant.
• The operating cost of a power plant is the amount of money needed to operate the power plant, typically taken over a year of operation. Examples of operating costs include the cost of fuel and maintenance.

The good news is that the operating costs of a nuclear power plant are low compared to fossil fuel power plants. This is mostly because nuclear power plants don’t use much fuel. A lump of uranium the size of a tennis ball can be used to produce the same amount of electricity as the amount of natural gas that could fill 340 Olympic swimming pools. Since the amount of fuel needed to power a nuclear power station is so low, changes in the price of uranium don’t affect the cost of electricity as severely. Compare this to natural gas where, as we have seen recently, the price of electricity generated by gas power stations is very sensitive to changes in the price of natural gas.

Now for the bad news. The capital costs for a nuclear power station are amongst the highest of any type of power plant. This is in part due to the safety measures that govern the construction and operation of the plant. Under current regulations, nuclear power plants must be able to show that they can continue to function even after a 1 in 10,000 year event¹¹. Additionally, the design of a nuclear power station is specific to the country and even the specific location of the power station. It also takes many highly qualified specialists to design and build nuclear power stations, further increasing the costs.

The future of nuclear power

Nuclear fusion is the process of combining two light atoms (such as hydrogen) into one heavier one. When the two atoms combine, energy is released. Fusion is how the sun generates energy. In the sun, the extreme temperatures and massive gravitational forces compress atoms and fuse them, releasing energy. Theoretically, the energy released by the process could then be used to generate electricity. Unsurprisingly, however, replicating the conditions found in the sun is quite a challenge.

What actually goes on inside a fusion reactor?

In a fusion reactor, extremely hot plasma is confined into a very small space. It is then ‘ignited’ after which fusion starts to take place. This releases energy, which heats the structure of the reactor and the coolant surrounding it. The coolant heats water, converting it into steam, which then drives a turbine and generates electricity.

Plasma is often defined as the fourth state of matter. Plasma is a gas-like state of matter that is so hot that the electrons are ripped away from the atoms. Plasma makes up most of the matter in the universe and can be seen in the form of lightning bolts, neon signs and the sun.

There are several benefits of fusion compared to fission

Firstly, fusion is inherently safe. Inherent safety is a principle of engineering design which aims to minimise or eliminate hazards in early development without relying heavily on external controls and safety measures. In fusion reactors, high temperatures and pressures are needed to maintain the reaction. This sounds dangerous, but if pressure or temperature is lost, the reactor will switch itself off¹².

The reactors also produce much less hazardous waste compared to fission reactors and use isotopes of hydrogen as fuel. One of these isotopes (tritium) is radioactive, however, it is a relatively weak source of radiation which cannot penetrate the skin. As long as the fuel is handled safely, it poses only a minimal risk to operators and the wider public¹³.

Similarly to fission, fusion could be used as a baseload to power the energy grid. As the fuel (hydrogen) is so readily available, the use of fusion would also contribute to the energy security of a nation. International politics would have little effect on energy production as long as the country could produce its own hydrogen.

So why aren’t we already using this seemingly perfect source of energy?

Well, for starters, the technology is still a long way from becoming commercially viable. It’s often said that, since the 1970s, commercial use of nuclear power has always been 40 years away. Clearly some people are more optimistic than others.

Fusion reactors have only started to produce more energy than they consume in the past year. In a large-scale fusion reactor, much of the energy produced by the reactor would go back into the reactor to maintain the conditions required for fusion. Additionally, maintaining these conditions still presents a significant challenge for scientists and engineers.

Even if we manage to control the fusion reactor, it remains a hostile environment. Hot plasma and the high-energy particles released by the reaction can damage the reactor. Scientists are currently developing materials that can withstand these conditions.

How can we overcome these challenges?

Machine learning and AI have been used to help control the conditions in fusion reactors. This could help give better control than the normal algorithms used to control the reactors and as machine learning continues to improve, we could see large-scale reactors under control.

More research into the construction and operation of fusion reactors will lead to more effective and hopefully cheaper solutions to the technical challenges currently facing fusion reactors.

Unfortunately, nuclear fusion is a long way from becoming commercially viable. Technological challenges, as well as the need for even more investment, mean that most experts think that large-scale fusion won’t be available until 2050 or even later¹⁴. Issues with cost and technology will continue to block the use of fusion for the foreseeable future. In addition, we must ensure that once fusion becomes viable, it is available globally, not just to the few rich countries which can afford to develop and invest in fusion.

However, this doesn’t mean that we shouldn’t be hopeful. With the hard work of scientists and engineers across the globe, we went from the first powered flight to landing on the moon in less than 70 years. Space flight would have been inconceivable in 1903 when the Wright brothers first flew their plane for 12 seconds. Who knows what the future will look like?

That’s the future, but what about right now?

Until fusion becomes available, we have a few options for creating a low-carbon energy grid. We can continue to invest in renewables and storage, build more nuclear (fission) power stations or continue to decrease the amount of energy we use through greater efficiency measures and more careful use of energy. In reality, the short to medium-term solution is a combination of the three. Exactly what combination, nobody knows. That’s up for you to decide.

References

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[2] World Bank. Electric power consumption (kWh per capita) – United Kingdom [Internet]. New York: World Bank; c2021 [cited 15 August 2023]. Available from https://data.worldbank.org/indicator/EG.USE.ELEC.KH.PC?locations=GB

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[7] World Nuclear Association. Safety of Nuclear Power Reactors [Internet]. World Nuclear Association; c2016 [Updated 2022, cited 15 August 2023] Available from https://www.world-nuclear.org/information-library/safety-and-security/safety-of-plants/safety-of-nuclear-power-reactors

[8] Nuclear Decommissioning Authority. Factsheet: Operating a nuclear power reactor [Internet]. UK Gov; c2013 [Cited 15 August 2023]. Available from https://ukinventory.nda.gov.uk/wp-content/uploads/2014/01/Fact-sheet-operating-a-nuclear-power-reactor.pdf

[9] UK Gov. Nuclear electricity in the UK [Internet]. UK Gov; c2019 [Cited 15 August 2023]. Available from https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/789655/Nuclear_electricity_in_the_UK.pdf

[10] Schlömer S, Bruckner T, Fulton L, Hertwich A, McKinnon A, Perczyk D, et al. Annex III: Technology-specific cost and performance parameters. In Climate Change 2014: Mitigation of Climate Change. Cambridge University Press, Cambridge; 2014 [cited 15 August 2023]

[11] Frazer-Nash Consultancy for the ONR. Underpinning the UK Nuclear Design Basis Critereon for Naturally Occuring Hazards. UK Gov; c2020 [cited 15 August 2023]. Issue No. 1

[12] Willis C, Liou J. Safety in Fusion [Internet]. IAEA; c2022 [cited 15 August 2023]. Available from https://www.iaea.org/bulletin/safety-in-fusion

[13] Canadian Nuclear Safety Commission. Facts about tritium [Internet]. Government of Canada. c2014 [Updated 2021, cited 15 August 2023] Available from https://nuclearsafety.gc.ca/eng/resources/fact-sheets/tritium.cfm#:~:text=Health%20effects,or%20absorption%20through%20the%20skin.

[14] Ball P, What is the future of fusion energy? [Internet]. Scientific American; c2023 [cited 15 August 2023] Available from https://www.scientificamerican.com/article/what-is-the-future-of-fusion-energy/#:~:text=Most%20experts%20agree%20that%20we,might%20add%20on%20another%20decade).

This article was written by Tom Gilsenan for EngBAM. The views expressed in this article are those of the author and do not necessarily reflect the views of EngBAM or the University of Birmingham as a whole.