Behind the scenes, French and British engineers are putting the finishing touches on a gigantic metal cylinder that will sit at the heart of Hinkley Point C-the UK’s first new nuclear power station in more than three decades, and a major test of whether nuclear power can truly underpin a low-carbon grid.
A 500-ton steel giant heads for Somerset
In late November 2025, French nuclear company Framatome signed off on one of the most sensitive components in the Hinkley Point C project: the reactor pressure vessel for Unit 2. The finished component is a 13-meter-long forged steel cylinder weighing about 500 tons, built to hold the uranium core of an EPR (European Pressurized Reactor).
Manufactured at Framatome’s Saint-Marcel site near Chalon-sur-Saône, the vessel has taken years of forging, machining, and testing. Workers there operate among massive hydraulic presses, ultra-precise welding tools, and heavy cranes. Every step is recorded, inspected, and checked again, because this is the part of the plant that directly surrounds the nuclear fuel.
The new vessel is designed to operate for up to 80 years under extreme temperature, pressure, and radiation without losing structural integrity.
Far from being a simple metal shell, the reactor vessel is engineered like an armored safe for the core. It must withstand pressures above 150 bar and temperatures near 300°C, while staying resilient against decades of neutron bombardment. Any defect in the steel-any microcrack or welding flaw-can become a serious safety concern later.
As final checks concluded on November 28, 2025, the vessel was slowly lifted and secured onto a heavy transport cradle. Its next leg will take it by sea and road to the Hinkley Point C site in Somerset, on England’s southwest coast, where Unit 2’s concrete containment structure and dome are already in place.
The second French-built vessel for Hinkley Point C
This is the second time a French-made EPR vessel has crossed the English Channel. The vessel for Hinkley Point C Unit 1, forged at Le Creusot, reached the site in early 2023 and was installed in the reactor building at the end of 2024.
Unit 2 is following a similar path, with the civil works for its reactor building progressing in parallel. Once on site, the 500-ton cylinder will be lowered into the reactor pit using one of the most powerful lifting systems ever used on a UK construction project.
Each step of the installation sequence is tightly choreographed. The vessel goes in before much of the piping and internal structures, and is then surrounded by safety systems, control instrumentation, and shielding. Any misalignment can delay the entire schedule-one reason these milestones are closely watched by both EDF and the UK government.
Hinkley Point C and the UK’s nuclear rethink
For years, large nuclear projects in Europe have been associated with cost overruns and schedule delays. The EPR design-used at Flamanville in France and Olkiluoto in Finland-was heavily criticized as budgets grew and completion dates slipped.
Hinkley Point C is the first new nuclear station to be built in the UK since the 1990s, and is expected to supply about 7% of the country’s electricity demand once both reactors run at full power.
Despite a boom in offshore wind and rapid solar growth, UK policymakers have concluded that large amounts of round-the-clock, low-carbon capacity will still be needed. Gas plants provide that today, but they bring volatile fuel costs and high emissions. That has put nuclear back at the center of strategy.
Hinkley Point C consists of two EPR units, each rated at about 1,630 MW. Together, they are expected to supply electricity to roughly six million homes. Construction began in 2018. Unit 1’s dome was installed in 2023, marking the end of the heaviest civil works for that reactor. Current plans point to first power around 2030, with decades of continuous operation expected if the plant performs as designed.
Steam generators: the other steel giants
Alongside the pressure vessel, Framatome has also completed the first two steam generators for Unit 2. These are huge heat exchangers-each 25 meters tall and weighing about 520 tons-designed to transfer heat from the reactor’s primary loop to a separate water loop that drives the turbines.
They resemble oversized horizontal drums packed with thousands of tubes. Hot, pressurized water from the reactor core flows around the tubes, heating cooler water inside them without mixing. That separation is one of the key safety barriers that helps keep radioactive material contained.
- Reactor pressure vessel: Holds the fuel and coolant at high pressure.
- Steam generators: Turn hot reactor coolant into steam for the turbines.
- Containment building: Concrete and steel structure enclosing core systems.
- Control systems: Monitor and regulate power, temperature, and safety parameters.
The first steam generator for Hinkley Point C arrived in Somerset in May 2024 and was installed in July of that year. The remaining units are scheduled to arrive by 2026, aligning with system tests required to demonstrate reliable operation before fuel is loaded.
The price tag and the long game
Project costs for Hinkley Point C have increased multiple times since approval. Current estimates place the total between £31 billion and £34 billion (in 2015 prices). The financing includes a long-term contract for difference, which guarantees EDF a set price per megawatt-hour, indexed to inflation.
Critics argue the guaranteed price is high compared with recent offshore wind contracts and question whether nuclear can remain competitive as renewables and storage mature. Supporters counter that Hinkley provides firm capacity that does not depend on weather and can stabilize the grid when wind output drops and demand peaks.
EDF and its partners see Hinkley Point C as a model for future EPR projects in the UK, especially the planned Sizewell C site on the Suffolk coast.
A strategic goal is to turn Hinkley’s hard-won lessons into cost and schedule improvements for follow-on plants. Standardized design, repeated use of supply chains, and a more experienced workforce could narrow the gap between nuclear and other clean technologies in the 2030s.
French engineering at the heart of the UK energy mix
Despite tensions around Brexit, nuclear energy has remained an area of close cooperation between France and the UK. EDF, majority-owned by the French state, leads the Hinkley Point C consortium and coordinates thousands of on-site workers. Framatome, another major French company, supplies key components such as vessels, steam generators, and control systems.
This cooperation goes beyond Hinkley. The same EPR technology is used at Taishan in China and is planned for Sizewell C. Engineers in France, the UK, Finland, and China share operating experience, exchange data on materials aging, and refine maintenance strategies for critical components like the reactor vessel.
Where EPR reactors stand worldwide
The shipment of the Hinkley vessel is part of a broader story: the gradual rollout of EPR units globally after a difficult start. While early projects faced major delays, some are now operating at full power and delivering large volumes of low-carbon electricity to national grids.
| Country | Site | Reactor | Status (late 2025) | Capacity (MW) | Service / target date |
|---|---|---|---|---|---|
| France | Flamanville | Flamanville 3 | Final commissioning phase | 1,630 | 2024–2026 (ramp-up) |
| Finland | Olkiluoto | Olkiluoto 3 | In operation | 1,600 | 2023 |
| China | Taishan | Taishan 1 | In operation | 1,660 | 2018 |
| China | Taishan | Taishan 2 | In operation | 1,660 | 2019 |
| United Kingdom | Hinkley Point C | HPC 1 | Under construction | 1,630 | 2030 (planned) |
| United Kingdom | Hinkley Point C | HPC 2 | Under construction | 1,630 | 2031 (planned) |
| United Kingdom | Sizewell C | SWC 1 & 2 | Authorized project | 2 × 1,630 | 2034–2035 (planned) |
What makes an EPR different?
The EPR is a so-called Generation III reactor, designed after the Chernobyl and Fukushima accidents, with more safety layers than earlier designs. It uses four independent safety trains instead of two, meaning multiple sets of pumps, valves, and generators can back one another up.
The core is enclosed in a double containment system: an inner prestressed concrete structure with a steel liner and an outer shell designed to protect against external events such as an aircraft impact. The design also includes a “core catcher,” a dedicated structure intended to trap and cool molten fuel in an extreme accident, limiting the risk of a major release.
For non-specialists, one way to visualize the system is as a series of boxes inside boxes. The fuel sits in a steel vessel. That vessel sits inside a thick concrete structure. Around that are safety systems, emergency cooling, and monitoring equipment designed to keep the core under control under both normal and abnormal conditions.
Risks, benefits, and future scenarios
Nuclear projects like Hinkley Point C involve clear tradeoffs. On one hand, they require enormous upfront capital, tight regulation, and long construction timelines. On the other, once operating, they produce steady, low-carbon power with relatively small land footprints.
From a climate standpoint, adding two large reactors can displace millions of tons of CO₂ each year compared with gas-fired generation. That effect compounds over decades. If Hinkley, Sizewell, and possible later plants all come online, the UK’s reliance on fossil fuels for baseload power could shrink sharply by the late 2030s.
At the same time, long-term waste management, decommissioning, and security must be handled with great care. The reactor vessel now leaving France will outlast most of the people who built it. Its story extends far beyond the political cycles shaping today’s energy debates.
For households, the impact is likely to appear less as a single dramatic change and more as a steady backdrop: a grid that stays reliable during windless evenings, electric cars charging overnight from low-carbon sources, and industrial sites able to plan around predictable power supplies. The 500-ton steel giant heading to Somerset is one of the hidden anchors of that future system.
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