Remote monitoring of Molten Core-Concrete Interaction experiment with Optical Fibre Sensors & perspectives to improve nuclear safety – DISCOMS project

Laurent Maurin (1, 2) , Pierre Ferdinand (2) , V. Bouyer (3, 4) , A. Denoix (3, 4) , G. Jouvin (3, 2) , Stéphane Rougeault (1, 2) , C. Journeau (3, 4) , D. Molina (3, 4) , P. Tena (3, 4) , Y. Ouerdane (5)

1 LCFO - Laboratoire Capteurs Fibres Optiques
2 LIST (CEA) - Laboratoire d'Intégration des Systèmes et des Technologies
3 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
4 SMTA - Service Mesures et modélisation des Transferts et des Accidents graves
5 LHC - Laboratoire Hubert Curien

The DISCOMS project (Distributed Sensing for Corium Monitoring and Safety) aimed at providing innovative solutions not requiring local electrical power supplies, for remote monitoring of a severe nuclear accident. The solutions are based on both long length SPNDs (Self Powered Neutron Detectors) and on distributed OFSs (Optical Fibre Sensors) capable to detect the onset of a severe accident, the corium pouring on the containment building concrete basemat, and its interaction with the concrete floor under the reactor vessel, until it spreads in the core catcher (EPR case). This paper mainly focuses on these last three detection targets achievable with distributed OFSs. It is based on the results of a Molten Core & Concrete Interaction (MCCI) experiment, namely VULCANO, held in June 2018 with a concrete crucible equipped with overall ~ 180 m long optical fibre sensing cables. This small scale experiment (50 kg of prototypical corium) has demonstrated the ability of distributed OFSs to remotely provide useful data during the MCCI run: i) temperature profiles images up to about 580°C (single wavelength Raman DTS reflectometer) until cooling down to room temperature, ii) high spatial-resolution frequency shifts profiles, due to combined (non-selective) strain and temperature influences (Rayleigh OFDR and Brillouin reflectometers), and iii) cables lengths ablated by the corium on sections weakened by the temperature (Raman DTS, Rayleigh OFDR, telecom and photon counting reflectometers).

Keywords: Nuclear Power Plant; nuclear safety; severe nuclear accident; corium; concrete basemat; instrumentation; sensor; nuclear instrumentation; Optical Fiber Sensor; Distributed and Quasi-distributed sensing; reflectometry; distributed measurement; remote monitoring; power-supply free sensors; optical sensing cables; MCCI (Molten Core-Concrete Interaction) experiment

Domains: Instrumentation and Detectors [physics.ins-det]; Optics / Photonic

Laurent Maurin, Pierre Ferdinand, V. Bouyer, A. Denoix, G. Jouvin, et al.. Remote monitoring of Molten Core-Concrete Interaction experiment with Optical Fibre Sensors & perspectives to improve nuclear safety – DISCOMS project. EPJ Web of Conferences, 2020, ANIMMA 2019 – Advancements in Nuclear Instrumentation Measurement Methods and their Applications, 225, pp.08004. ⟨10.1051/epjconf/202022508004⟩. ⟨cea-03910535⟩