NSUF 20-3018: Microstructure characterization of 6Li(n,a)3H reaction damage sapphire claddings
The high temperature stability of sapphire optical fiber offers opportunities for in-situ testing of material parameters in advanced reactors. However, its use as a sensor has been limited by the inability to manufacture a fiber cladding with the appropriate optical properties for enhanced wave guiding. A method for improving the optical properties of a fiber by creation of an internal cladding has recently been demonstrated using the 6Li(n,α)3H reaction in the OSURR.
The proposed work is a 7-month project utilizing The Ohio State University Research Reactor (OSURR) for sample irradiation and the Idaho National Laboratory (INL) Irradiated Materials Characterization Laboratory (IMCL) for post-irradiation examination. The primary objective of this work is to characterize the radiation damage and subsequent heat treatment induced microstructure changes in sapphire optical fiber to which a damage cladding has been added. The project involves 2 days of work at the OSURR, during which the damage cladding will be applied to 4 previously unmodified single crystal sapphire optical fibers. Following some post-irradiation extraction and annealing work, the fibers will be shipped to INL IMCL for post irradiation examination (PIE). PIE will involve the preparation of 7 TEM lamellas using FIB techniques. These lamellas will represent a spectrum of samples from high, low and no flux regions of the fiber, as well as long, short and no anneal times. All lamellas will be imaged using TEM to determine the size and distribution of nanovoids which are expected to be present in the fibers based on the fibers improved performance and a similar study performed using a proton beam in 2013. Two of the 7 lamellas will be heated in-situ to monitor the evolution of the microstructure while being heated. These same two lamellas will be measured using EELS before and after heating in order to attempt to detect and quantify the content of tritium and helium. Detection and quantification of the tritium and helium content in the fibers is the secondary objective of this work.
The significance of measuring the void size and spatial distribution is that it will provide validation of the mechanism predicted to be responsible for improved fiber performance. These measurements will form a basis for improving fundamental understanding that can be applied towards tailoring sapphire properties to be more suitable for sensing applications in nuclear reactors. Direct measurement of tritium in the cladding, if successful, could result in less radiological restrictions to the use of cladded fibers, allowing more rapid expansion of the technology, if it is found that tritium is present in the bubbles in lesser concentrations than previously predicted.
Additional Info
| Field | Value |
|---|---|
| Abstract | The high temperature stability of sapphire optical fiber offers opportunities for in-situ testing of material parameters in advanced reactors. However, its use as a sensor has been limited by the inability to manufacture a fiber cladding with the appropriate optical properties for enhanced wave guiding. A method for improving the optical properties of a fiber by creation of an internal cladding has recently been demonstrated using the 6Li(n,α)3H reaction in the OSURR. The proposed work is a 7-month project utilizing The Ohio State University Research Reactor (OSURR) for sample irradiation and the Idaho National Laboratory (INL) Irradiated Materials Characterization Laboratory (IMCL) for post-irradiation examination. The primary objective of this work is to characterize the radiation damage and subsequent heat treatment induced microstructure changes in sapphire optical fiber to which a damage cladding has been added. The project involves 2 days of work at the OSURR, during which the damage cladding will be applied to 4 previously unmodified single crystal sapphire optical fibers. Following some post-irradiation extraction and annealing work, the fibers will be shipped to INL IMCL for post irradiation examination (PIE). PIE will involve the preparation of 7 TEM lamellas using FIB techniques. These lamellas will represent a spectrum of samples from high, low and no flux regions of the fiber, as well as long, short and no anneal times. All lamellas will be imaged using TEM to determine the size and distribution of nanovoids which are expected to be present in the fibers based on the fibers improved performance and a similar study performed using a proton beam in 2013. Two of the 7 lamellas will be heated in-situ to monitor the evolution of the microstructure while being heated. These same two lamellas will be measured using EELS before and after heating in order to attempt to detect and quantify the content of tritium and helium. Detection and quantification of the tritium and helium content in the fibers is the secondary objective of this work. The significance of measuring the void size and spatial distribution is that it will provide validation of the mechanism predicted to be responsible for improved fiber performance. These measurements will form a basis for improving fundamental understanding that can be applied towards tailoring sapphire properties to be more suitable for sensing applications in nuclear reactors. Direct measurement of tritium in the cladding, if successful, could result in less radiological restrictions to the use of cladded fibers, allowing more rapid expansion of the technology, if it is found that tritium is present in the bubbles in lesser concentrations than previously predicted. |
| Award Announced Date | 2020-02-05T14:24:25.643 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Alina Zackrone, Raymond Cao |
| Irradiation Facility | Ohio State University Research Reactor |
| PI | Joshua Jones |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 3018 |