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 "title": "EUROfusion DEMO",
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 "excerpt": "EUROfusion DEMO, or EU-DEMO, is Europe's planned demonstration fusion power plant, designed to deliver 300 to 500 megawatts of net electricity to the grid with a closed tritium fuel cycle.",
 "snippet": "EUROfusion DEMO, or EU-DEMO, is Europe's planned demonstration fusion power plant, designed to deliver 300 to 500 megawatts of net electricity to the grid with a closed tritium fuel cycle.",
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 "markdown": "# EUROfusion DEMO\n\n**EUROfusion DEMO** (EU-DEMO) is Europe's planned demonstration fusion power plant, the successor to the ITER experiment in the European roadmap to fusion electricity. It is designed to demonstrate the net production of 300 to 500 megawatts of electricity to the grid while operating with a closed tritium (radioactive hydrogen isotope used as fusion fuel) fuel cycle, meaning the spent tritium fuel is reprocessed on site.<sup>[1](https://euro-fusion.org/programme/demo/)</sup> DEMO is intended to test technologies, physics regimes and control routines for running a fusion reactor not as a scientific experiment but as a power plant, although not at the price and quantities of commercial power plants.<sup>[2](https://euro-fusion.org/glossary/demo/)</sup> The project is currently in its conceptual design phase under the [EUROfusion](https://www.edgepedia.org/eurofusion) consortium; no site or construction date has been set.<sup>[3](https://www.nuclearnewsnetwork.com/industry-trackers/fusion-energy-companies/eu-demo)</sup>\n\n| Key fact | Detail |\n|---|---|\n| Central requirement | 300 to 500 MW net electricity to the grid, with a closed tritium fuel cycle<sup>[1](https://euro-fusion.org/programme/demo/)</sup> |\n| Machine concept | Conventional tokamak; pre-conceptual design foresees a major radius of about 9 m and a fusion power of about 2,000 MW<sup>[4](https://www-pub.iaea.org/MTCD/publications/PDF/CRCP-FUS-001webRev.pdf)</sup> |\n| Design status | Conceptual design phase began 5 July 2022, after the Pre-Concept Design Phase (2014–2020) closed with a gate review<sup>[5](https://www.euronuclear.org/news/eurofusion-started-demo-conceptual-design-phase/)</sup><sup> • </sup><sup>[6](https://www.sciencedirect.com/science/article/pii/S0920379621007353)</sup> |\n| Tritium breeding | Required tritium breeding ratio of 1.05, with a target of at least 1.15 including neutronic modeling margins<sup>[7](https://www.mdpi.com/2673-4362/4/3/37)</sup> |\n| Candidate blankets | Water-cooled lithium-lead (WCLL) and helium-cooled pebble bed (HCPB) concepts, using EUROFER97 reduced-activation steel<sup>[7](https://www.mdpi.com/2673-4362/4/3/37)</sup> |\n| Expected operation | Start of operation expected around 2050<sup>[4](https://www-pub.iaea.org/MTCD/publications/PDF/CRCP-FUS-001webRev.pdf)</sup> |\n| Funding | €549 million Euratom grant for 2021–2025, plus €222 million announced in March 2026 for 2026–2027<sup>[8](https://www.europarl.europa.eu/RegData/etudes/BRIE/2026/785740/EPRS_BRI%282026%29785740_EN.pdf)</sup> |\n\n## Role in the European roadmap\n\nThe EUROfusion roadmap, first published in 2012 and updated in 2017, organizes European fusion research around the sequential development of JET, ITER, and DEMO.<sup>[9](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A52025SC0054)</sup> Building and operating DEMO, which will connect fusion electricity to the grid, is the subject of the roadmap's last phase.<sup>[1](https://euro-fusion.org/programme/demo/)</sup> The roadmap's short-term items include the Concept Design phase of DEMO and construction of the IFMIF-DONES materials testing facility in Granada, Spain, which will test and validate the materials for future fusion power plants like DEMO; the medium term includes the Engineering Design phase of DEMO with industrial involvement.<sup>[10](https://euro-fusion.org/eurofusion/roadmap/)</sup>\n\nWith the transition from ITER to DEMO, fusion is meant to move from a science-driven, laboratory-based exercise to an industry-driven and technology-driven program. The roadmap states that the design, construction, and operation of DEMO require full involvement of industry, so that after a successful DEMO operation industry can take on responsibility for commercial fusion power.<sup>[10](https://euro-fusion.org/eurofusion/roadmap/)</sup>\n\n## Design phases and governance\n\n**Pre-conceptual phase.** The Pre-Concept Design Phase ran from 2014 to 2020 and focused on advancing the technical basis of the design, with an integrated systems-engineering approach that assessed critical system interdependencies and the uncertainties of design assumptions. A phase-gate review process was introduced, culminating in the first formal DEMO-wide gate review at the end of the phase.<sup>[6](https://www.sciencedirect.com/science/article/pii/S0920379621007353)</sup> On 14 December 2020 an independent expert panel presented the results of a full-week review, recommending among other things a transition to a design-driven project culture, stronger centralized resources for inter-system design integration, and quick resolution of open issues in the plasma scenario, plasma exhaust, remote maintenance, tritium breeding blankets, and building layout.<sup>[11](https://euro-fusion.org/eurofusion-news/expert-panel-demo-design/)</sup>\n\n**Conceptual design phase.** Following the gate review, EUROfusion developed a DEMO project charter updating governance, objectives, schedule, and scope, and the Concept Design Phase started in 2021 with two sub-phases: a concept selection of key design and technology solutions for each main DEMO system, with a gate (G2) in 2024–2025 to confirm that remaining feasibility issues have been resolved, and a concept validation to consolidate an integrated system concept design foreseen to be completed around the end of 2027. A transition phase of about two years is foreseen for the concept design review and preparation of the Engineering Design Phase, and early dialogue with regulatory bodies on licensing is planned during the phase.<sup>[12](https://www.sciencedirect.com/science/article/pii/S0920379621007365)</sup> EUROfusion announced the start of conceptual design activities on 5 July 2022.<sup>[5](https://www.euronuclear.org/news/eurofusion-started-demo-conceptual-design-phase/)</sup>\n\n## Technical requirements and key systems\n\nDEMO must demonstrate technologies that previous experiments were not designed to test: controlling a more powerful plasma than has previously existed, safely generating electricity consistently, and performing regular, rapid, and reliable maintenance of the plant.<sup>[1](https://euro-fusion.org/programme/demo/)</sup> The EUROfusion Fusion Technology Programme identifies several requirements for a robust conceptual design: selecting the breeding blanket and divertor concept, designing the first wall for heat loads that may exceed those assumed in experimental settings, choosing the minimum pulse duration and the corresponding mix of plasma heating systems, enabling all maintenance work to be carried out remotely via manipulators, and incorporating nuclear safety issues from the very beginning of conception.<sup>[1](https://euro-fusion.org/programme/demo/)</sup>\n\n**Breeding blanket.** The blanket is the internal component of the reactor wall that absorbs energy from the fusion reaction, ensures the tritium breeding process, and shields components outside the reaction chamber from fast fusion neutrons.<sup>[1](https://euro-fusion.org/programme/demo/)</sup> The two driver candidate concepts for EU-DEMO are the water-cooled lithium-lead (WCLL) and helium-cooled pebble bed (HCPB) concepts, and the in-vessel components are assumed to be manufactured with [EUROFER97](https://www.edgepedia.org/eurofer97) reduced-activation ferritic-martensitic steel. The blanket must breed 5 percent more tritium than is burnt in fusion to cover fuel-cycle losses, giving a required tritium breeding ratio of 1.05, with a target of at least 1.15 once neutronic modeling margins are included. A progressive operation approach is anticipated, with a total blanket lifetime of about 7 full power years, split into a starter set lasting about 2 full power years and a second set covering the remaining 5.<sup>[7](https://www.mdpi.com/2673-4362/4/3/37)</sup> To ensure tritium self-sufficiency, about 85 percent of the plasma must be covered by the breeding blanket, and design work found that a radial build of about 1.40 m (60 cm vacuum vessel plus about 80 cm inboard breeding blanket) provides sufficient shielding.<sup>[13](https://doi.org/10.1016/j.fusengdes.2019.01.141)</sup>\n\n**Divertor.** Because uncertainties surrounding the physics of plasma exhaust are central to reactor design, EUROfusion has assessed alternative divertor configurations as a risk-mitigation strategy in case the [ITER divertor](https://www.edgepedia.org/iter-divertor) solution cannot be extrapolated to reactor-relevant machines. Quantitative assessment with multifluid simulations showed that alternative configurations such as the Super-X and [X-divertor](https://www.edgepedia.org/x-divertor) provide a larger operating space than the single-null configuration, including lower argon seeding levels, lower separatrix density for comparable divertor protection, and greater resilience to high-power operation, though these configurations also entail many engineering challenges.<sup>[14](https://conferences.iaea.org/event/214/contributions/17375/)</sup>\n\n**Remote maintenance.** Because plant downtime must be minimized to keep costs down and maximize electricity generated, remote maintenance is described as device-defining for a fusion power plant, strongly influencing the plant's architecture. The UKAEA's Remote Applications in Challenging Environments (RACE) center is a key participant in developing DEMO's remote handling.<sup>[15](https://www.ukaea.org/work/demo/)</sup>\n\n## Timeline and external assessment\n\nThe IAEA World Survey of Fusion Devices records EU-DEMO as expected to start operating by 2050.<sup>[4](https://www-pub.iaea.org/MTCD/publications/PDF/CRCP-FUS-001webRev.pdf)</sup> The 2018 roadmap long version stated that DEMO construction would have to start in the early 2040s, shortly after ITER achieves Q = 10 operation, to achieve fusion electricity early in the second half of the century.<sup>[16](https://euro-fusion.org/wp-content/uploads/2022/10/2018_Research_roadmap_long_version_01.pdf)</sup>\n\nThis schedule has drawn criticism. In a 2025 interim evaluation, the European Commission, based on independent expertise, judged that EUROfusion is not fit to achieve commercial exploitation of fusion power generation. Independent experts considered the roadmap based on sequential JET-ITER-DEMO development overly complex and unrealistic from a timeline perspective, with the main concerns relating to the lack of testing and qualification of components under relevant fusion conditions. A particular worry was that the ITER Organization's re-examination of the project baseline could result in a 10-year delay to first experiments and leave the industrial supply chain idle.<sup>[9](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A52025SC0054)</sup> The EUROfusion roadmap was being redrafted to take account of ITER delays.<sup>[17](https://scipub.euro-fusion.org/wp-content/uploads/WPPMICP16_14960_submitted.pdf)</sup> A 2025 economic study concluded that reaching a commercially attractive fusion plant after DEMO requires design improvements aimed at cost reduction in addition to simply scaling up net electric output, and that truly cost-competitive plants would need advanced concepts such as a steady-state tokamak or a stellarator.<sup>[18](https://www.sciencedirect.com/science/article/pii/S0920379625003023)</sup>\n\nFunding has continued at scale: following a €549 million grant from 2021 to 2025, the European Commission announced an additional €222 million under the 2026–2027 Euratom work program, partly to establish a further public-private partnership on nuclear fusion.<sup>[8](https://www.europarl.europa.eu/RegData/etudes/BRIE/2026/785740/EPRS_BRI%282026%29785740_EN.pdf)</sup>\n\n## Socio-economic studies\n\nUnder Mission 7 of the European Research Roadmap for Fusion Energy Realisation, EUROfusion extends beyond technical DEMO design studies to research on the economic and social dimensions of fusion. The Work Programme on Socio-Economic Studies (WPSES), which continues work begun in 2001 under the [European Fusion Development Agreement](https://www.edgepedia.org/european-fusion-development-agreement), uses global energy scenarios and European surveys to examine future prospects and public perceptions. To measure how the public views fusion, two large-scale surveys were carried out, one in 2018 and one in November 2023, with each drawing 20,000 respondents from around Europe.<sup>[1](https://euro-fusion.org/programme/demo/)</sup>\n\n## References\n\n1. [Demonstration Power Plant DEMO, EUROfusion](https://euro-fusion.org/programme/demo/)\n2. [Glossary Term: DEMO, EUROfusion](https://euro-fusion.org/glossary/demo/)\n3. [EU DEMO (EUROfusion Demonstration Power Plant), Nuclear News industry tracker](https://www.nuclearnewsnetwork.com/industry-trackers/fusion-energy-companies/eu-demo)\n4. [World Survey of Fusion Devices 2022, IAEA](https://www-pub.iaea.org/MTCD/publications/PDF/CRCP-FUS-001webRev.pdf)\n5. [EUROfusion Started The DEMO Conceptual Design Phase, European Nuclear Society](https://www.euronuclear.org/news/eurofusion-started-demo-conceptual-design-phase/)\n6. [The EU DEMO staged design approach in the Pre-Concept Design Phase, Fusion Engineering and Design](https://www.sciencedirect.com/science/article/pii/S0920379621007353)\n7. [Advancements in Designing the DEMO Driver Blanket System at the EU DEMO Pre-Conceptual Design Phase, MDPI](https://www.mdpi.com/2673-4362/4/3/37)\n8. [Nuclear fusion: State of play, European Parliamentary Research Service](https://www.europarl.europa.eu/RegData/etudes/BRIE/2026/785740/EPRS_BRI%282026%29785740_EN.pdf)\n9. [Interim Evaluation of the Council Decision (Euratom) 2021/281, EUR-Lex](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A52025SC0054)\n10. [Roadmap, EUROfusion](https://euro-fusion.org/eurofusion/roadmap/)\n11. [Expert panel approves next DEMO design phase, EUROfusion](https://euro-fusion.org/eurofusion-news/expert-panel-demo-design/)\n12. [The plan forward for EU DEMO, Fusion Engineering and Design](https://www.sciencedirect.com/science/article/pii/S0920379621007365)\n13. [An overview of the EU breeding blanket design strategy as an integral part of the DEMO design effort, Fusion Engineering and Design](https://doi.org/10.1016/j.fusengdes.2019.01.141)\n14. [An Assessment of Alternative Divertors for the European DEMO, IAEA FEC 2020](https://conferences.iaea.org/event/214/contributions/17375/)\n15. [DEMO: Demonstrating commercial fusion energy, UKAEA](https://www.ukaea.org/work/demo/)\n16. [European Research Roadmap to the Realisation of Fusion Energy (long version), EUROfusion](https://euro-fusion.org/wp-content/uploads/2022/10/2018_Research_roadmap_long_version_01.pdf)\n17. [EUROFUSION WPPMI-CP(16) 14960, EUROfusion publications](https://scipub.euro-fusion.org/wp-content/uploads/WPPMICP16_14960_submitted.pdf)\n18. [Economic study on the key aspects required for a commercial fusion power plant design based on EUROfusion-DEMO, Fusion Engineering and Design](https://www.sciencedirect.com/science/article/pii/S0920379625003023)\n\n---\n*Topic: Encyclopedia › Technology and the built world › Energy technology › Fusion energy*\n\n*Initially written Oct 22, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n",
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 "speakable": "EUROfusion DEMO, or EU-DEMO, is Europe's planned demonstration fusion power plant, designed to deliver 300 to 500 megawatts of net electricity to the grid with a closed tritium fuel cycle."
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