High-dose temperature-dependent neutron irradiation effects on the optical transmission and dimensional stability of amorphous fused silica

Numerical Analysis of Radiation Effects on Fiber Optic Sensors

“…Figure 5 reveals that the length-change effect on the Bragg wavelength compensates for the RI effect, producing a zero Bragg wavelength shift up to 102 kGy. At higher doses (1049-1540 kGy), the compaction effect on the Bragg wavelength dominates; as a result, the Bragg wavelength shifts towards the shorter wavelengths, thus supporting the experimental results reported in [17,26,36]. Please note that in [17,26,36], Nuetron-irradiation-induced shift was reported.…”

“…While our simulation results for FBG demonstrate a redshift of the Bragg wavelength (λ B ) due to the radiation-induced RI change, experimental results reported in [17,26,36] showed a radiation-induced blueshift of λ B . Comparing the simulation results to the experimental work reported in [17,26,36] suggests that additional parameters must be considered for simulating our designs.…”

“…If the attenuation effects are not considered, Figure 4 would indicate that an increasing RI change resulting from the radiation dose is accompanied by an increase in the amplitude of the Bragg peak, since we are independently analyzing the RIC effect. While our preliminary simulation results showed a redshift of the Bragg wavelength as a function of increasing doses, this contradicted the experimental findings reported in [17,26,36]. In the next section, we discuss another key aspect-one that involves RIC effects and considers the length change-for accurately predicting the resonance shift behavior in FBG.…”

Demonstrate embedding of sensors in a relevant microreactor component

“…On the other hand, spatially distributed strain can be measured by directly embedding metal coated fibers in the component and compensating for temperature effects using loosely-coupled fiber-optic temperature sensors or TCs, similar to previous efforts [2,3]. Fiber-optic sensors have been demonstrated at temperatures up to 1,000°C [16,17,21] and in high radiation environments [22][23][24][25][26][27][28][29][30]. For extremely high-temperature applications beyond 1,000°C, singlecrystal sapphire optical fibers can be used [30][31][32].…”

Demonstration of Embedded Sensors in Ceramic Structures

“…Like Type K thermocouples, fiber-optic temperature sensors are well-suited to measure temperatures over the expected range of the TCR core, but the higher temperatures required for embedding might pose challenges for fused silica-based fiber-optic sensors (typically limited to <1,000°C) [12]. Silica fiber-based sensors can also survive the expected radiation dose over the planned period of TCR core operation [13][14][15]. Sapphire fiber-based sensors could extend the operational temperature range to 1,500°C or higher [16][17][18][19], although these sensors have a relatively low technology readiness level.…”