EDF will keep Sizewell B running for another 20 years, until 2055. The pressurised water reactor in Suffolk, which began generating in 1995, was originally due to close in 2035. That extension adds two decades of low-carbon baseload power to Britain’s grid.
As The Chemical Engineer reported, the Office for Nuclear Regulation approved the life extension after a detailed safety review. No new nuclear plants are needed for this, just continued operation of existing kit.
What this means for your electricity bill
Nuclear power is cheap to run but expensive to build. Sizewell B’s extension avoids the capital cost of a new reactor, EDF spent roughly £3bn building it in the 1990s, but the ongoing operating costs are relatively low. The plant generates about 1.2 GW, enough for around 1 million homes.
The catch is how nuclear costs flow to households. Under the Contracts for Difference (CfD) scheme, new nuclear projects like Hinkley Point C receive a fixed strike price of £92.50 per MWh (indexed to 2012 prices), which adds roughly £10–£15 per year to a typical dual-fuel bill. Existing plants like Sizewell B are not on CfDs, they sell power at wholesale prices, which currently average around £70–£90 per MWh. That means the extension does not trigger new subsidy payments.
But there is a broader effect. Every MWh of nuclear generation displaces gas-fired power, which sets the marginal price in the UK market. When gas prices spike, as they did in 2022, nuclear plants reduce the volume of expensive gas that sets the wholesale price. Ofgem estimates that nuclear output during the 2022 crisis saved households roughly £15–£20 per year on wholesale costs, though this figure is sensitive to market conditions.
Who pays for nuclear safety and decommissioning
Nuclear plants require ongoing safety upgrades and eventual decommissioning. The Nuclear Decommissioning Authority already holds a £23bn liability for the UK’s legacy sites. Sizewell B’s extension means EDF will fund its own decommissioning through a separate fund, but the costs are ultimately recovered through electricity sales, meaning households pay marginally more than they would for a plant that never needed decommissioning.
Energy Saving Trust notes that nuclear generation currently accounts for about 15% of UK electricity. If Sizewell B closes in 2055, the UK will need replacement capacity, likely a mix of offshore wind, solar, and new nuclear. For homeowners planning long-term investments like heat pumps or electric vehicle chargers, the stability of nuclear baseload reduces the risk of future price spikes that could make electrification less economical.
What this means for your EPC and home upgrades
A more stable grid with lower carbon intensity makes heat pumps and EVs more attractive. The carbon intensity of UK electricity has fallen from 500 gCO2/kWh in 2010 to around 200 gCO2/kWh today, partly due to nuclear. Lower carbon electricity means heat pumps produce fewer indirect emissions, improving the environmental, and potentially the EPC, score of a home that switches from gas to a heat pump.
The Boiler Upgrade Scheme currently offers £7,500 off the cost of a heat pump installation. With nuclear providing reliable baseload, the grid can absorb more electrified heating without requiring massive new gas backup. That is a concrete benefit for homeowners: lower running costs relative to gas, and a better EPC rating that can increase property value by 5–10% according to some estate agent surveys.
Yet the extension is not a silver bullet. Sizewell B will need major refurbishments around 2040, and EDF has not published cost estimates for those. If costs rise, they could show up in bills. Homeowners should not bet their retrofit plans on nuclear prices staying flat, but they can reasonably expect that the grid will remain low-carbon and relatively stable for the next three decades.
Households planning a heat pump or EV purchase can proceed with confidence that the grid will support them. The Sizewell B extension buys time for the UK to build more renewables and storage, which should further reduce bills in the long run. For now, the immediate action is simple: check if you qualify for the Boiler Upgrade Scheme or EV chargepoint grants, and factor in EPC improvements before the next winter.
Frequently Asked Questions
Not directly, the plant sells power at market rates, not subsidised prices. But by displacing expensive gas generation, it helps keep wholesale prices lower than they would be otherwise. Ofgem estimates the effect is roughly £15–£20 per year during periods of high gas prices.
Yes, the UK grid carbon factor used in EPC calculations includes nuclear generation. A lower grid carbon intensity means heat pumps and electric heating score better on EPC assessments, which can improve your property's rating by one or two bands.
