A NMR and SANS study of alkali-borosilicate behaviour under thermal neutron irradiation

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The internal structure of several alkali-borosilicate glasses has been studied when exposed to a high thermal neutron flux. More specifically, the different glasses we are interested in are widely used around the globe for neutron guide manufacturing and show drastically different resistance to irradiation. Samples were irradiated with the thermal flux from T4 experimental tube in ILL¿s High Flux Reactor up to a fluence of several n/cm. The experimental tools employed for the structural analysis were Nuclear Magnetic Resonance (NMR) and Small Angle Neutron Scattering (SANS). NMR measurements allowed to detect the modification of atoms¿ close environment and these results have been correlated to evolutions at macroscopic scale. In addition, neutron scattering measurements have demonstrated the possibility to detect phase segregation in a zinc-alkali-borosilicate.
Financial support from the IR-RMN-THC Fr3050 CNRS for conducting the research is gratefully acknowledged. This work benefited from the use of the SasView application, originally devel- oped under NSF award DMR-0520547. SasView contains code de- veloped with funding from the European Union’s Horizon 2020 research and innovation programme under the SINE2020 project, grant agreement N º654000. We would like to thank the guide manufacturers for the assistance they provided throughout this study. Romain Boffy acknowledges financial support from the ESS- Bilbao Consortium. Finally, the study here exposed would not have been possible without the combined effort s of ILL staff through- out several years, specially the SMAE, BPC, Bloc-Pile and Radio- Protection services.