Development and first use of an experimental device for fission-induced spectrometry applied to neutron flux monitoring

Maxime Lamotte (1, 2) , G. de Izarra (1, 2) , C. Jammes (1, 2)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 LDCI - Laboratoire de Dosimétrie, de Contrôle-commande et Instrumentation

In order to provide dependable neutron flux instrumentation for Generation IV Sodium-cooled Fast Reactors (SFR), the French Atomic and Alternative Energies Commission (CEA) is investigating the feasibility of an innovative technology based on the optical signal produced within a fission chamber. In such gaseous detectors, neutrons interact with fissile material releasing heavy ions in the MeV-range, eventually leading to spontaneous photon emission in the ultraviolet-to-infrared range thanks to gas excitation and ionization. In this paper , the process of light generation is analyzed through semi-empirical models and custom-developed codes. A specific instrumentation has been defined and manufactured to emulate optical fission chambers and collect basic spectroscopic data required for model-based development approach. That testing device was named PSEG, which stands for Prototype of Scintillator Electrodes-Gas. Experimental validations have been carried out: the ionized argon gas exhibited no local thermodynamic equilibrium. Furthermore, the broadening of selected argon emission lines due to pressure change offers a promising self-diagnosis capability for future optical fission chambers.

Mots clés: fission chambers; radiation-hard detectors; gaseous detectors; gas scintillation

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Instrumentations et Détecteurs [physics.ins-det]; Physique des plasmas [physics.plasm-ph]

Maxime Lamotte, G. de Izarra, C. Jammes. Development and first use of an experimental device for fission-induced spectrometry applied to neutron flux monitoring. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, In press, 953, pp.163236. ⟨10.1016/j.nima.2019.163236⟩. ⟨cea-02932104⟩