Study of radiation-induced dimensional changes in SiO2.

SCK•CEN Mentor

Goussarov Andrei, agoussar@sckcen.be, +32 (0)14 33 85 06

Expert group

Nuclear Engineering Office

SCK•CEN Co-mentor

Uytdenhouwen Inge , iuytdenh@sckcen.be , +32 (0)14 33 31 71

Introduction

Radiation exposure of glasses and ceramics can cause changes in the material density and, since a non-uniform density changes can result in a deformation this effects is of concern for a number of application of glasses and ceramics ionizing radiation environments. In particular, the effect was investigated for fused silica.

Thanks to its radiation hardness fused silica is material of choice for optical fibre sensors (OFS) intended for operation in radiation environment. Such can bring substantial advantages over conventional sensing approaches for in-situ measurement in fission Material Testing Reactors (MTRs) and other nuclear research or industrial facilities: easy remote sensing, possibilities of multiplexing, passive operation, low sensitivity to electromagnetic interference, compact size, high resolution and accuracy even under high radiation dose and high temperature, once necessary adaptations have been achieved. Other applications are also possible.

Recently a special Fabry Perot Sensor (FPS) has been developed to perform displacement in a MTR core [1, 2]. Despite of a scheme adapted for high levels of radiation, measurement drifts have been observed. Until now, we have supposed that the induced FPS error, can be deduced from the post mortem measurements made by W.Primak on bulk silica glass at 50°C [3]. He found that vitreous silica under fast neutron irradiation tends towards the “metamict phase” with about 3% density increase compared to the initial state. However, results obtained on bulk samples are not directly applicable to optical fibres. Because of the drawing process inducing anisotropic stress, we may suspect that optical fibres show anisotropic behaviour when they compact under radiation. Furthermore, glass used for the core and cladding parts of the fibres are doped with different chemical elements to construct the refractive-index profile mandatory to guide the light into the core. Another open question is the effect of temperature. W.Primak performed irradiation at ~50°C while the for our applications temperatures in a range 200 – 900°C are of interest.

 

References

[1] G. Cheymol, A. Gusarov, S. Gaillot, C. Destouches and N. Caron, “Dimensional Measurements Under High Radiation With Optical Fibre Sensors Based on White Light Interferometry - Report on Irradiation Tests"; IEEE Trans. Nucl. Sci., vol.61, no.4, pp. 2075-2081, 2014. ,

[2] G. Cheymol, J.F. Villard, A. Gusarov, B. Brichard, Fibre optic extensometer for high radiation and high temperature nuclear applications, IEEE Trans.Nucl.Sci., vol.60, no.5, pp. 3781-3784, 2013.

[3] W.Primak, "Fast neutron induced changes in quartz and vitreous silica", Phys. Rev.B, vol. 110, no.6, pp. 1240-1254, 1958.

 

Objective

The goal of the master thesis is the assessment of the combined effect of temperature and gamma-radiation on the density of SiO2. The student will be involved in the experimental work, such as preparation of silica samples, initial characterization and post-irradiation measurements. The work in the lab will require precise execution of laboratory requirements.

The theoretical part consists in the data analysis and reporting. To fulfil this task a basic knowledge of a solid state physics is required. On the theoretical level, interest to understanding of defects generation in SiO2 with different dopants as a function of the dose and temperature is expected.

The project will be performed in a close collaboration with a third year PhD student from UGhent.  

The minimum diploma level of the candidate needs to be

Academic bachelor

The candidate needs to have a background in

Physics , Other , Optical materials; radiation effects