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Reactor cycles

Reactor startups and shutdowns take place at 8.30 a.m., except on Mondays when they take place at 11.30 a.m.

2026

Cycle n°199 48 days 24/03 - 11/05/2026 56 MW
Cycle n°200 56 days 08/06- 03/08/2026 47.9 MW
Cycle n°201 58 days 01/09 - 29/10/2026 46.2 MW
Cycle n°198 63 days
26/08- 07/10/2025 42 days 41.2 MW
07/10 - 14/10/2025 7 days 55 MW
14/10 - 28/10/2025 14 days 41.2 MW
Cycle n°197 63 days 05/05- 06/07/2025 42.5 MW
Cycle n°195 49 days 27/02 - 16/04/2024 54.8 MW
Cycle n°196 56 days 14/05 - 09/07/2024 47.9 MW
Cycle n°192 7 days 01/03 - 08/03/2023 28 MW
Cycle n°192
bis 		20 days 23/03 - 18/04/2023 44 MW
Cycle n°192
ter 		36 days 22/08 - 27/09/2023 44 MW
Cycle n°193 55 days 11/05 - 05/07/2023 48.6 MW
Cycle n°194 47 days 24/10 - 02/12/2023
04/12 - 12/12/2023 		57 MW
Cycle n°189 62 days 27/01/2021 - 30/03/2021 43 MW
Cycle n°190 64 days 27/01/2021 - 30/03/2021 42 MW
Cycle n°191 50 days 24/08/2021 - 13/10/2021 54 MW
Cycle n°187 48 days 9/01/2020 - 26/02/2020 56 MW
Cycle n°188 48 days 11/08/2020 - 28/09/2020 56 MW
Cycle n°185 52 days 13/06/2019 - 04/08/2019 50 MW
Cycle n°185 48 days 28/08/2019 - 15/10/2019 56 MW
Cycle n°182 56 days 28/02/2018 - 25/04/2018 52.5 -58.3 MW
Cycle n°183 (delayed) 51 days 22/05/2018 - 12/07/2018 52.5 MW
Cycle n°184 52 days 03/09/2018 - 25/10/2018 52.5 MW
Cycle n°181 48 days 19/01/2017 - 8/03/2017 52.5 MW
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Reactor cycles
Reactor startups and shutdowns take place at 8.30 a.m., except on Mondays when they take place at 11.30 a.m. 2026 Cycle n°199 48 days 24/03 - 11/05/2026 56 MW Cycle n°200 56 days 08/06- 03/08/2026 47.9 MW Cycle n°201 58 days 01/09 - 29/10/2026 46.2 MW 2025 Cycle n°198 63 days 26/08- 07/10/2025 42 da...
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Environnement & Safety
A strong safety and security culture are fundamental principles for any nuclear facility. At the ILL, technical and organisational measures are implemented to reduce any risks to a level deemed acceptable. This constitutes the field of nuclear safety, which encompasses measures designed to:Ensure th...
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Reactor overview
Under its dome, the ILL operates the world’s most intense continuous neutron source: the High-Flux Reactor (HFR, known officially as Installation Nucléaire de Base n° 67), a nuclear research reactor designed to provide very intense neutron beams. The reactor operates 24 hours a day in cycles of app...