The pros and cons of nuclear energy come down to a trade-off between reliability and cost. Nuclear power provides steady, low-carbon electricity with a small land footprint, but it carries high upfront costs, long construction delays, and a waste management system that is still searching for a permanent home in the UK.
If you are looking for a power source that does not depend on the weather, nuclear fits that role. If you are concerned about how much new projects will cost consumers or where the spent fuel will go, the UK’s recent record gives some concrete answers.
How nuclear power works
Nuclear fission splits heavy nuclei, mainly uranium-235, inside a reactor core. The heat generated raises steam to drive a turbine, much as in coal or gas plants; only the heat source is different.
The UK fleet currently consists of advanced gas-cooled reactors (AGRs) at four stations (Hartlepool, Heysham 1, Heysham 2 and Torness), plus one pressurised water reactor (PWR), Sizewell B. That is nine reactors in total, with a net capacity of 5,883 MWe, all operated by EDF. The two new projects, Hinkley Point C and Sizewell C, each use two reactors of the EPR design.
The advantages
Low lifecycle carbon emissions
Nuclear power is often described as zero-emission, but a more accurate description is very low lifecycle emissions. According to the IPCC AR5 (2014), the median lifecycle emission for nuclear is 12 gCO2eq/kWh. This is comparable to onshore wind (11 g) and offshore wind (12 g), and about one sixty-eighth of coal (820 g).
Emissions come from mining, enrichment, construction and decommissioning. In the IPCC table, direct operating emissions are zero; the lifecycle figure comes from infrastructure and the supply chain.
Reliability and high capacity factor
Nuclear plants generate power continuously, regardless of weather. In the UK, nuclear stations had the highest load factor of any technology in 2025, at 64.0%. By comparison, offshore wind managed 36.4%, onshore wind 24.1% and solar PV 11.1%.
Globally, the average nuclear capacity factor was 83.7% in 2025. In the UK, Sizewell B achieved a 99% load factor in 2025, producing 10.4 TWh, and Torness ran at 82%, generating 8.6 TWh. The UK fleet’s overall figure was held down by refuelling and maintenance outages on an ageing set of stations.
Small land footprint
Nuclear requires much less land than most other low-carbon sources. Our World in Data, using UNECE (2021) data, calculates that per unit of electricity nuclear needs about 50 times less land than coal and 18–27 times less than ground-mounted solar PV.
Safety record
Measured by deaths per terawatt-hour (TWh), nuclear is one of the safest energy sources. Our World in Data (2021 dataset) puts nuclear at 0.03 deaths/TWh, similar to wind (0.035) and only slightly above solar (0.019). Gas stands at 2.821 and hydropower at 1.3, a figure driven largely by the 1975 Banqiao Dam failure. Coal stands at 24.62 deaths/TWh and brown coal at 32.72.
The nuclear figure includes 433 deaths from Chernobyl (1986) and 2,314 from Fukushima (2011) over 96,876 TWh generated between 1965 and 2021. Most of the Fukushima deaths in this count are linked to the evacuation rather than to radiation exposure.
The disadvantages
High costs and delays
New nuclear projects have a reputation for cost overruns. Hinkley Point C was estimated at £18 billion at approval in 2016. In January 2024 EDF revised this to £31–34 billion (2015 prices). In February 2026 EDF put the cost at £35 billion (2015 prices), which The Telegraph reported as about £48 billion in 2026 prices.
Unit 1 now has a base-case start date of 2030; it was originally due by the end of 2025. EDF attributed the delays to lower-than-expected productivity in electromechanical installation work and booked a €2.5 billion write-down in its 2025 results.
Sizewell C reached its Final Investment Decision in July 2025. The government puts its target construction cost at about £38 billion (2024 prices) and says this is about 20% less than Hinkley Point C. The two headline figures are in different price bases (2024 and 2015), so they are not directly comparable.
Radioactive waste
The UK’s 2022 Inventory for Geological Disposal lists 769,000 m³ of packaged waste for final disposal. By volume, 62.24% is intermediate-level waste and 24.94% is uranium. By radioactivity, however, spent fuel accounts for 90.91%.
High heat-generating waste makes up only about one tenth of the volume but about 95% of the radioactivity. Some waste remains hazardous for hundreds of thousands of years.
The UK holds about 140 tonnes of civil plutonium at Sellafield. In January 2025 the government decided to immobilise this plutonium for geological disposal rather than reuse it as fuel.
Sellafield, the largest nuclear complex in Western Europe, has a forecast decommissioning cost of £136 billion, with full remediation expected to take until 2125. The National Audit Office said in October 2024 that it could not conclude the site was achieving value for money yet.
No permanent disposal site yet
The UK has not yet chosen a site for its Geological Disposal Facility (GDF). In January 2025 Nuclear Waste Services named Mid Copeland and South Copeland in Cumbria as “Areas of Focus”. This is not a final site selection.
The Lincolnshire option ended in 2025 after the county council withdrew. Regulators expect the first environmental permit application around 2028 and a site licence application in the 2030s.
The programme’s whole-life cost was estimated in 2019 at £20.3 billion (baseline) to £53.3 billion (upper, including risk) over about 190 years. In August 2025 the National Infrastructure and Service Transformation Authority (NISTA) gave the GDF programme a RED rating, calling it “unachievable as currently structured”.
Accident and proliferation risk
Serious accidents are rare but can be severe and long-lasting, as the contamination and evacuations at Chernobyl and Fukushima showed. Enrichment and reprocessing could also be diverted to weapons, which is why the IAEA safeguards civil programmes.
The UK angle
Nuclear generated 35.9 TWh in the UK in 2025, down 12% from 2024 and the lowest output since the 1980s. It accounted for 12.2% of total UK generation of 293.6 TWh, while renewables provided 52.1% (see the live GB electricity mix for today’s figures).
The current fleet faces a steep decline. In July 2026 Heysham 1 and Hartlepool were extended to March 2030, and Heysham 2 and Torness are also due to close in March 2030, although EDF keeps all four under review. For Sizewell B, EDF and the government agreed outline terms in July 2026 for a Contract for Difference extending its life to 2055, with EDF funding about £800 million of refurbishment; the final contract is not yet confirmed.
The government’s target is up to 24 GW of nuclear by 2050, about 25% of electricity. Hinkley Point C (3,260 MWe across two units) has a 2030 base case for Unit 1. Sizewell C (3.2 GW) is due to start “in the 2030s”, and the first small modular reactors are targeted for Wylfa in the mid-2030s.
Sizewell C is financed through a Regulated Asset Base (RAB) model, meaning consumers contribute during construction, on average about £1 per household per month. The UK government holds an initial 44.9% stake.
Frequently asked questions
What are the main pros and cons of nuclear energy?
The main advantages are low lifecycle carbon emissions (12 gCO2eq/kWh), high reliability (the highest UK load factor in 2025, at 64.0%), small land use and a low death rate per unit of electricity (0.03 deaths/TWh). The main disadvantages are high construction costs, long delays, radioactive waste with no permanent UK disposal site yet, the risk of rare but severe accidents, and proliferation concerns.
Is nuclear power low-carbon?
Yes. The IPCC AR5 (2014) puts the median lifecycle emission for nuclear at 12 gCO2eq/kWh. This is similar to wind (11–12 g) and far lower than gas (490 g) and coal (820 g). Emissions come from mining, enrichment, construction and decommissioning, not from operating the reactor.
How much of the UK’s electricity comes from nuclear?
In 2025 nuclear generated 35.9 TWh, 12.2% of total UK generation. This was a 12% drop from 2024, caused by outages at the ageing fleet.
How safe is nuclear power compared with other energy sources?
Measured by deaths per unit of electricity, nuclear is among the safest sources. Our World in Data (2021 dataset) shows 0.03 deaths per TWh for nuclear, compared with 24.62 for coal and 2.821 for gas. The figure includes deaths from the Chernobyl and Fukushima disasters.
Why is Hinkley Point C so expensive and when will it open?
EDF now puts the cost of Hinkley Point C at £35 billion (2015 prices), with a 2030 base case for Unit 1. EDF has blamed lower-than-expected productivity in electromechanical installation work. The strike price is £89.50/MWh (2012 prices).
What happens to the UK’s nuclear waste?
The UK’s inventory amounts to 769,000 m³ of packaged waste awaiting a Geological Disposal Facility (GDF). Areas of Focus in Cumbria were named in January 2025, but no site has been chosen. Regulators expect the first permit application around 2028.