NSUF 18-1535: Non-destructive X-ray computed tomography analysis of SiC composite tubes neutron-irradiated with and without a high radial heat flux
Silicon carbide (SiC) fiber-reinforced SiC matrix (SiC-SiC) composites are of interest for accident-tolerant fuel cladding in light water reactors (LWRs) because of their low activation, high strength at elevated temperatures, relatively low neutron absorption, and steam oxidation resistance. However, SiC and SiC-SiC composites undergo inversely temperature-dependent, irradiation-induced swelling, and modeling work has predicted that thermal gradients through the cladding wall thickness can have a significant effect on the stress states of SiC components during irradiation. The proposed work will conduct x-ray computed tomography (XCT) analysis of SiC-SiC tubes neutron-irradiated with and without a radial high heat flux. The magnitude of both the heat flux and inner and outer tubes temperatures is relevant to the LWR fuel cladding condition. The tube samples are composed of a chemical vapor-infiltrated SiC-SiC composite with a multi-layered structure of an inner composite and outer monolithic layer, fabricated by General Atomics. The XCT analysis will detect potential irradiation-induced cracking. This is one of the best nondestructive methods to directly observe micro-cracks in ceramic materials. Comparison of the microstructures among SiC-SiC composites irradiated with and without high heat flux will provide insight into the effects of temperature gradients on cladding damage. In addition, XCT observation will provide important data to experimentally validate thermo-mechanical modeling of SiC-SiC tubes through determination of the stress state based on the distribution of irradiation-induced micro-cracks. The post-irradiation examination will be conducted in the LAMDA laboratory. A total of two multi-layered SiC-SiC tubes that have been neutron-irradiated with and without a radial heat flux will be investigated. These samples were previously irradiated in HFIR to a neutron dose of 2.3 dpa. For the tube sample irradiated with a high heat flux, the nominal inner and outer surface irradiation temperatures are ~470 and ~300°C, respectively. XCT will be conducted using a Zeiss Xradia Versa 520. Three scans will be conducted for each specimen. The first scan will evaluate the whole volume of a specimen with a length of 16 mm, outer diameter of 8.5 mm, and inner diameter of ~7.1 mm. The typical pixel size of the constructed image is ~5 um. The second and third scans will evaluate two different selected areas at high magnification. The scan volume and the pixel size of the constructed image will be about 2×2×2 mm3 and less than 1 um, respectively. Each scan with low and high magnification settings will take approximately 10 h. It was previously demonstrated that this XCT system captures micro-cracks in neutron-irradiated SiC-SiC tubes. Data processing software (FEI Amira-Avizo 3D) will be used to quantify the XCT images. Micro-cracks in neutron-irradiated, multi-layered SiC-SiC tubes will be characterized based on length and spatial distribution by three-dimensional imaging data analysis. It is anticipated that the duration of the testing will be around 4 months.
추가 정보
| 필드 | 값 |
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| Abstract | Silicon carbide (SiC) fiber-reinforced SiC matrix (SiC-SiC) composites are of interest for accident-tolerant fuel cladding in light water reactors (LWRs) because of their low activation, high strength at elevated temperatures, relatively low neutron absorption, and steam oxidation resistance. However, SiC and SiC-SiC composites undergo inversely temperature-dependent, irradiation-induced swelling, and modeling work has predicted that thermal gradients through the cladding wall thickness can have a significant effect on the stress states of SiC components during irradiation. The proposed work will conduct x-ray computed tomography (XCT) analysis of SiC-SiC tubes neutron-irradiated with and without a radial high heat flux. The magnitude of both the heat flux and inner and outer tubes temperatures is relevant to the LWR fuel cladding condition. The tube samples are composed of a chemical vapor-infiltrated SiC-SiC composite with a multi-layered structure of an inner composite and outer monolithic layer, fabricated by General Atomics. The XCT analysis will detect potential irradiation-induced cracking. This is one of the best nondestructive methods to directly observe micro-cracks in ceramic materials. Comparison of the microstructures among SiC-SiC composites irradiated with and without high heat flux will provide insight into the effects of temperature gradients on cladding damage. In addition, XCT observation will provide important data to experimentally validate thermo-mechanical modeling of SiC-SiC tubes through determination of the stress state based on the distribution of irradiation-induced micro-cracks. The post-irradiation examination will be conducted in the LAMDA laboratory. A total of two multi-layered SiC-SiC tubes that have been neutron-irradiated with and without a radial heat flux will be investigated. These samples were previously irradiated in HFIR to a neutron dose of 2.3 dpa. For the tube sample irradiated with a high heat flux, the nominal inner and outer surface irradiation temperatures are ~470 and ~300°C, respectively. XCT will be conducted using a Zeiss Xradia Versa 520. Three scans will be conducted for each specimen. The first scan will evaluate the whole volume of a specimen with a length of 16 mm, outer diameter of 8.5 mm, and inner diameter of ~7.1 mm. The typical pixel size of the constructed image is ~5 um. The second and third scans will evaluate two different selected areas at high magnification. The scan volume and the pixel size of the constructed image will be about 2×2×2 mm3 and less than 1 um, respectively. Each scan with low and high magnification settings will take approximately 10 h. It was previously demonstrated that this XCT system captures micro-cracks in neutron-irradiated SiC-SiC tubes. Data processing software (FEI Amira-Avizo 3D) will be used to quantify the XCT images. Micro-cracks in neutron-irradiated, multi-layered SiC-SiC tubes will be characterized based on length and spatial distribution by three-dimensional imaging data analysis. It is anticipated that the duration of the testing will be around 4 months. |
| Award Announced Date | 2018-09-17T12:02:28.16 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Kory Linton |
| Irradiation Facility | None |
| PI | Christian Deck |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1535 |