# Is France Finally Ready to Dismantle Its First Gas-Cooled Reactor?

Mid-2028 is now the operational start date for dismantling the heat exchangers at Chinon A2 — the world's first Uranium Naturel Graphite Gaz (UNGG) reactor to undergo active dismantling — after EDF subsidiary Cyclife validated the contractual strategy for that initial phase following more than three and a half years of joint engineering studies.

Chinon A2 is one of six UNGG gas-cooled reactors spread across Bugey, Chinon, and St Laurent-des-Eaux that EDF is currently decommissioning. The six reactors entered service between 1963 and 1972. With the exception of Chinon A1, which closed in 1973, all six operated for more than 20 years before shutdown. Chinon A2 serves as the lead site for EDF's immediate dismantling strategy across the entire UNGG fleet, and the project is expected to take six years once operations begin. Before work can start, a public inquiry into the UNGG dismantling strategy — scheduled for 2027 — must be completed, and the formal dismantling decree must enter into force.

The milestone matters not just for France but for a global cohort of gas-cooled reactor operators watching for a transferable decommissioning methodology.

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## What the Heat Exchanger Phase Actually Involves

The first operational phase will dismantle, in series, the equipment housed in Chinon A2's four heat exchanger rooms. Those heat exchangers transferred heat from carbon dioxide — heated in the reactor core — to water in the secondary circuit, producing steam. Sequencing the work across four rooms in series, rather than simultaneously, is a deliberate risk-management choice that allows lessons from each room to be applied to the next.

Critically, Cyclife noted the Chinon A2 operation will benefit directly from experience already accumulated during dismantling of the Chinon A3 reactor heat exchangers. That cross-application of lessons-learned is central to EDF's broader strategy of compressing timelines across its UNGG fleet: the company's stated objective is to dismantle facilities in the shortest timeframe possible.

Stéphanie Proust, EDF Chinon A-AMI project manager, described the milestone as "an essential step forward in preparing for an exceptional industrial project, which is set to serve as a benchmark for EDF's entire UNGG programme."

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## The Graphitech Joint Venture and the Wider Decommissioning Play

The commercial and technological infrastructure underpinning this project has been building for years. In December 2019, EDF and Veolia established the **Graphitech** joint venture specifically targeting graphite-technology reactor decommissioning. Graphitech's initial mandate was to develop an optimised decommissioning scenario for Chinon A2 by 2028 and to run a testing programme for the remote-operation tools required for the graphite core work — the technically harder phase that follows the heat exchanger campaign.

That testing programme launched in 2022, using full-scale models in a development and qualification phase. Graphitech has since produced an outline decommissioning methodology covering the five remaining UNGG reactors: where Chinon A2's methodology can be transposed directly, it will be; where site-specific differences require additional engineering, that gap work has been identified.

Graphitech's ambitions extend well beyond France. The joint venture is explicitly seeking contracts for gas-cooled reactor dismantling in **Italy, Japan, Lithuania, Spain, and the UK**. The UK angle is particularly commercially significant: the UK's Magnox fleet — also graphite-moderated, CO₂-cooled — represents one of the largest volumes of legacy gas-cooled reactor decommissioning work in the world. A proven Chinon A2 methodology, validated through actual operations, would be a meaningful competitive credential when bidding into that market.

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## Why This Matters for Advanced Nuclear

The direct connection to SMR development is indirect but real. As the advanced nuclear industry designs next-generation gas-cooled reactors — [High Temperature Gas-Cooled Reactors](https://smrintel.com/glossary/htgr) feature prominently in several SMR development programmes — the ability to demonstrate a credible, costed end-of-life pathway strengthens the full lifecycle argument for gas-cooled technology. Regulators and utilities increasingly demand decommissioning plans with real industrial precedent, not conceptual ones.

From a regulatory standpoint, Chinon A2 is also a test case for how French nuclear safety authorities handle the public inquiry process for complex legacy decommissioning. The 2027 public inquiry timeline, and the subsequent dismantling decree, will set procedural precedents that could influence how France approaches licensing for new builds — including SMRs — that eventually reach end-of-life decades from now.

The six-year project timeline, once the mid-2028 start is achieved, means France will have meaningful operational data from Chinon A2 before 2035. That positions EDF and Graphitech to bid credibly on international contracts during what is expected to be a peak period for legacy gas-cooled reactor decommissioning globally.

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## Skeptical Notes

Several risks could shift the mid-2028 start date. The 2027 public inquiry is a mandatory regulatory gate, and public inquiries in France have historically run longer than initially planned when local opposition or technical complexity emerges. The dismantling decree cannot enter into force until that process concludes — meaning any inquiry delay pushes the operational start correspondingly.

There is also a sequencing risk inherent in the "lessons from Chinon A3" approach: if undocumented conditions are discovered during the Chinon A2 heat exchanger phase that differ materially from A3, the six-year timeline estimate will need revision. Remote-operation tooling, developed and qualified on full-scale models since 2022, will face its first real-world validation under actual radiological conditions.

Cost figures for the Chinon A2 project were not disclosed in Cyclife's announcement.

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## Key Takeaways

- **Mid-2028** is the planned operational start for dismantling Chinon A2's heat exchangers, subject to completion of a 2027 public inquiry and entry into force of the dismantling decree.
- Cyclife validated the contractual strategy after **more than three and a half years** of joint engineering studies with EDF's DP2D department.
- Chinon A2 is the **lead site** for EDF's immediate dismantling strategy across six UNGG reactors that entered service between 1963 and 1972.
- The **Graphitech joint venture** (EDF + Veolia, established December 2019) holds the broader UNGG methodology and is targeting international gas-cooled reactor decommissioning markets including Italy, Japan, Lithuania, Spain, and the UK.
- The first operational phase — dismantling equipment in four heat exchanger rooms in series — is expected to take **six years** in total.
- No project cost figures were disclosed by Cyclife.

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## Frequently Asked Questions

**What is a UNGG reactor?**
UNGG stands for Uranium Naturel Graphite Gaz — a French design of gas-cooled, graphite-moderated reactor that uses natural (unenriched) uranium fuel. Six UNGG reactors were built at Bugey, Chinon, and St Laurent-des-Eaux, entering service between 1963 and 1972. All have been shut down and are now in various stages of decommissioning by EDF.

**When will dismantling of Chinon A2 actually begin?**
Operations are planned to start in mid-2028, following a public inquiry into the UNGG dismantling strategy scheduled for 2027 and the subsequent entry into force of a formal dismantling decree.

**Who is doing the dismantling work at Chinon A2?**
EDF subsidiary Cyclife is the lead contractor, working in partnership with EDF's Deconstruction and Waste Projects Department (DP2D). The Graphitech joint venture — established by EDF and Veolia in December 2019 — is developing the broader UNGG decommissioning methodology and remote-operation tooling.

**Why does Chinon A2's decommissioning matter internationally?**
Gas-cooled, graphite-moderated reactors were built in multiple countries. Graphitech has explicitly identified potential markets for its methodology in Italy, Japan, Lithuania, Spain, and the UK. A successfully executed Chinon A2 project would provide the first fully operational reference case for this reactor type, strengthening bid credentials in those markets.

**What comes after the heat exchanger dismantling phase?**
The heat exchanger phase is described as the first operational phase. The graphite core itself — radiologically more complex — represents the subsequent and more technically challenging phase of the project. Remote-operation tools for core work have been in development and qualification testing since 2022.