High thermal neutron flux effects on structural and macroscopic properties of alkali-borosilicate glasses used as neutron guide substrate

The behaviour of four alkali-borosilicate glasses under homogeneous thermal neutron irradiation has been studied. These materials are used for the manufacturing of neutron guides which are installed in most facilities as devices to transport neutrons from intense sources such as nuclear reactors or spallation sources up to scientific instruments. Several experimental techniques such as Raman, NMR, SANS and STEM have been employed in order to understand the rather different macroscopic behaviour under irradiation of materials that belong to a same glass family. The results have shown that the remarkable glass shrinking observed for neutron doses below 0.5 · 10 18 n/cm 2 critically depends upon the presence of domains where silicate and borate network do not mix

Why neutron guides may end up breaking down? Some results on the macroscopic behaviour of alkali-borosilicate glass support plates under neutron irradiation

In this paper we report on a first part of a study on the mechanisms leading to brittle fracture in neutron guides made of glass as structural element. Such devices are widely used to deliver thermal and cold neu tron beams to experimental lines in most large neutron research facilities. We present results on macroscopic properties of samples of guide glass substrates which are subjected to neutron irradiation at relatively large fluences. The results show a striking dependence of some of the macroscopic properties such as density, shape or surface curvature upon the specific chemical composition of a given glass. The relevance of the present findings for the installation of either replacement guides at the existing facilities or for the deployment of instruments for ongoing projects such as the European Spallation Source is briefly discussed

Estudio de la idoneidad de un nuevo hormigón estructural fabricado con áridos ligeros reforzados con fibra de carbono sinterizados a partir de residuos

The suitability of three new lightweight aggregates containing carbon fiber residues (CAs) as components in structural lightweight concrete has been studied. Prismatic concrete specimens were prepared using these CAs as a coarse fraction. Additional specimens of normal-weight aggregate, commercial lightweight aggregate and mortar were prepared for comparison. The CA-concrete samples (CACs) have yielded compressive strength values between 35 and 55 MPa as well as low density and thermal conductivity results. Furthermore, the CACs have displayed the highest ratios of mechanical strength over density and the thermal conductivity, which means that there is a better balance between their mechanical and physical properties than in the other samples studied. These results indicate that the new CAs could have great potential for use in structural lightweight concrete, also complying with the principles of the Circular Economy.Este estudio pretende comprobar la idoneidad de unos novedosos áridos ligeros sinterizados con residuos de fibra de carbono (CAs) en la fabricación de hormigón ligero estructural. Se prepararon probetas prismáticas de hormigón, utilizando estos CAs como fracción gruesa, comparándose a su vez con probetas fabricadas con un árido convencional, un árido ligero comercial y mortero. Las muestras de hormigón con los áridos CA (en adelante CAC) han dado lugar a valores de resistencia a compresión entre 35 y 55 MPa, así como a resultados bajos de densidad y conductividad térmica, mostrando además las ratios más altas al relacionar estos tres parámetros. Esto indicaría por tanto un mejor equilibrio entre las propiedades mecánicas y físicas que los obtenidos en las otras muestras estudiadas. Estos resultados apuntan a que los nuevos CAs podrían tener un gran potencial para su uso en hormigón ligero estructural, cumpliendo además los principios de la Economía Circular

Total dose effects on negative voltage regulator

Abstract Functional failure at low dose level (4 Krad(Si)) on voltage regulators (LM137) from different manufacturers are analysed. Dose rate effects on parts hardness are evaluated, showing that lowering the dose rate degrade more the ICs in the range 55 rad(Si)/s-0,s rad(Si)/s A failure mechanism is proposed, mainly based on circuit analysis, voltage contrast measurements, local irradiation and local electrical measurements with probe station. A spice simulation was performed, providing quantitative informations on the degradation. In the light of such a failure analysis and dose rate Pagure (Saclay, France) panoramic Cobalt60 source of 20 000 Ci located few kilometres away from VBlizy plant. Remote testing were performed in VBlizy using LTS 2020 automatic tester from Analog Devices, Digital Signal Analyser DSA601 from Tekmnic and HP4172 from Helwett Packard. Delay between irradiation and remote testing is kept below one hour. Local irradiation are performed using scanning transmission electron microscope JEOL JSM840 with electron energy up to 40 Kev. Contrast voltage potential measurement were carried out using a IDS Shlumberger tester. Probing measurements were performed using Wentworth probe station MP900 and HP4145 from Helwett Packard. effects, practical implications on radiation assurance are discussed. FAILURE DESCRIPTION I. INTRODUCTION Bipolar linear ICs are usually known as quite hard parts regarding Total Dose effects, with typical dose hardness in the range 50 to 100 Krad(Si). Such a postulate comes mainly from the relative intrinsic high hardness of bipolar transistor and passive devices. The problem is that bipolar transistors and passive elements used in linear ICs are not similar to the well known elemental structures. Because of integration constraint and in order to minimise the number of mask steps during IC processing, PNP transistors are often lateral ones. Such a type of transistor is already known as Total Ionizing Dose (TID) sensitiveIl1. When using such a sensitive structure in critical function of linear IC, loss of functionality can be foreseen, as already predicted by Johnston 2. In this paper, we will focus on negative voltage regulator (LM137 type) from 4 different manufacturers. We will analyse the degradation mode, based on different test methods. LM137 is a three terminal adjustable output negative voltage regulator. Reference voltage of -1.250V can be delivered for input voltage (referred to output voltage) ranging from -4.2% to -41.25V. The 137 circuit, shown in figure 1, consists in start up circuit, intemal comparator, band gap reference, power output stage and prowtion circuitry. ILEXPERIMENTAL PROCEDUR

A versatile device for thermal neutron irradiation of materials at grazing incidence angles

12 pags., 11 figs., 6 tabs.This paper describes the design, construction, and test of a setup able to make thermal neutron irradiation at grazing angles of incidence on a sample lying inside an isotropic high neutron flux. Such characteristics are deemed to be very interesting for the future research facilities that will provide intense neutron beams. Indeed, collimated beams can be found easily in neutron sources around the globe, but the new equipment enables use of a relatively intense flux that will allow fast testing of materials. The aim of this study is the understanding of the mechanical stability of structural materials used for the manufacturing of neutron guides such as borosilicate glasses. This new equipment proved the unstability of some of these glasses to thermal neutron irradiation when exposed above a given fluence.We thank the guide manufacturers for the assistance they provided throughout this study. Romain Boffy would like to deeply thank Michael Kreuz for their scientific and technical help and also acknowledges financial support from the ESSBilbao Consortium. Finally, the study would not have been possible without the combined efforts of ILL staff throughout several years, specially the SMAE, BPC, Bloc-Pile, and Radio- Protection services. The authors thank them for their constant supportPeer Reviewe

High thermal neutron flux effects on structural and macroscopic properties of alkali-borosilicate glasses used as neutron guide substrate

6 págs.; 5 figs.; 5 tabs.The behaviour of four alkali-borosilicate glasses under homogeneous thermal neutron irradiation has been studied. These materials are used for the manufacturing of neutron guides which are installed in most facilities as devices to transport neutrons from intense sources such as nuclear reactors or spallation sources up to scientific instruments. Several experimental techniques such as Raman, NMR, SANS and STEM have been employed in order to understand the rather different macroscopic behaviour under irradiation of materials that belong to a same glass family. The results have shown that the remarkable glass shrinking observed for neutron doses below 0.5·10 n/cm critically depends upon the presence of domains where silicate and borate network do not mix. 2015 Elsevier B.V.We would like to thank the guide manufacturers for the assistance they provided all along this study. Romain Boffy acknowledges financial support from the ESS-Bilbao Consortium. Financial support from the TGIR-RMN-THC Fr3050 CNRS for conducting the research is gratefully acknowledged. This work benefited from SasView software, originally developed by the DANSE project under NSF award DMR-0520547.Peer Reviewe

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

9 pags., 14 figs., 9 tabs.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

Effects of thermal neutron radiation on a hardware-implemented machine learning algorithm

International audienceHardware-implemented machine learning algorithms are finding their way in various domains, including safety-critical applications. This has demanded these algorithms to perform correctly even in harsh environmental conditions, such as in avionics altitudes. Support Vector Machine (SVM) is an important Machine Learning that has been target of hardware implementation in recent years. This is the first work to asses both Binary and Multiclass SVMs under thermal neutron radiation, a type of particle noticeably present in high altitudes. A fault injection campaign along with a radiation test with the D50 thermal neutron source, at the Intitut Laue-Languevin, has been performed. The results show a high intrinsic fault tolerance for both varieties of the SVM algorithm, especially for the Multiclass SVM