NSUF 18-1226: In Situ TEM Investigation on Fission Gas Behavior in U-10Zr
Gaseous fission products such as Xe and Kr form bubbles within nuclear fuel materials during operation. The fission gas bubbles affect the fuel performance by causing gaseous swelling, degrading thermal conductivity, and compromising fuel integrity. Fission gas behavior is therefore an important factor determining fuel performance. Fission gas bubbles form within grains (intragranular) as well as on grain boundaries (intergranular). The evolution mechanisms and influence on bulk properties differs between intragranular and intergranular bubbles. In metallic nuclear fuels such as U-10Zr, there exist a series of possible phases within the fuel operating temperature range. Thus, the fission gas behavior also depends on the fuel phase. Thus, quantitative information such as the size distribution and number density of both types of bubbles in difference phases is crucial to predict the degradation of bulk fuel properties as well as to support the optimization and validation of advanced fuel performance codes. This proposed study aims at utilizing the in situ TEM ion irradiation capability at IVEM-Tandem to produce these quantitative references for U-10Zr, a promising metallic fuel material for fast reactors. The U-10Zr samples used in this proposed study was legacy samples from Argonne National Laboratory’s Integral Fast Reactor (IFR) project. Aside from as-fabricated U-10Zr samples, the same samples were also pre-implanted by 84 MeV Xe ions at five different temperatures (600ºC, 650ºC, 675ºC, 700ºC, and 750ºC). The peak implanted Xe concentration is ~1.8%, which is equivalent to a 10%FIMA burnup. The temperatures were selected to cover all five phase domains of U-10Zr within its operating temperature range. TEM lamellae will be prepared from both as-fabricated and pre-implanted U-10Zr samples. The as-fabricated lamellae will be irradiated by 200 keV Xe ions up to 2.62E15 ions/cm2 at 600ºC, 650ºC, 675ºC, 700ºC, and 750ºC, respectively. The selection of the ion energy ensures that the majority of the Xe ions will be retained inside the lamellae, while the target dose provides an average Xe concentration equivalent to 5%FIMA. On the other hand, the pre-implanted specimens will be irradiated by 1 MeV Kr ions up to 1.80E16 ions/cm2. At this energy, few Kr ions will be deposited within the lamellae, only creating radiation damages and consequent enhanced diffusion in those pre-implanted U-10Zr lamellae. The Xe bubbles formed in irradiated TEM lamellae will be characterized by Fresnel edges in underfocus-overfocus TEM images. The size distribution and number density of both intragranular and intergranular Xe bubbles will be measured from the TEM images taken at different doses and in various phases. The results will provide precious experimental results for the model optimization and validation of the advanced fuel performance code for U-10Zr metallic fuel in fast reactors. The in situ TEM ion irradiation investigation takes one days for each sample. As there will be ten samples (five irradiation temperatures and as-fabricated/pre-implanted), we request ten (10) days of IVEM-Tandem facility time.
Additional Info
| Field | Value |
|---|---|
| Abstract | Gaseous fission products such as Xe and Kr form bubbles within nuclear fuel materials during operation. The fission gas bubbles affect the fuel performance by causing gaseous swelling, degrading thermal conductivity, and compromising fuel integrity. Fission gas behavior is therefore an important factor determining fuel performance. Fission gas bubbles form within grains (intragranular) as well as on grain boundaries (intergranular). The evolution mechanisms and influence on bulk properties differs between intragranular and intergranular bubbles. In metallic nuclear fuels such as U-10Zr, there exist a series of possible phases within the fuel operating temperature range. Thus, the fission gas behavior also depends on the fuel phase. Thus, quantitative information such as the size distribution and number density of both types of bubbles in difference phases is crucial to predict the degradation of bulk fuel properties as well as to support the optimization and validation of advanced fuel performance codes. This proposed study aims at utilizing the in situ TEM ion irradiation capability at IVEM-Tandem to produce these quantitative references for U-10Zr, a promising metallic fuel material for fast reactors. The U-10Zr samples used in this proposed study was legacy samples from Argonne National Laboratory’s Integral Fast Reactor (IFR) project. Aside from as-fabricated U-10Zr samples, the same samples were also pre-implanted by 84 MeV Xe ions at five different temperatures (600ºC, 650ºC, 675ºC, 700ºC, and 750ºC). The peak implanted Xe concentration is ~1.8%, which is equivalent to a 10%FIMA burnup. The temperatures were selected to cover all five phase domains of U-10Zr within its operating temperature range. TEM lamellae will be prepared from both as-fabricated and pre-implanted U-10Zr samples. The as-fabricated lamellae will be irradiated by 200 keV Xe ions up to 2.62E15 ions/cm2 at 600ºC, 650ºC, 675ºC, 700ºC, and 750ºC, respectively. The selection of the ion energy ensures that the majority of the Xe ions will be retained inside the lamellae, while the target dose provides an average Xe concentration equivalent to 5%FIMA. On the other hand, the pre-implanted specimens will be irradiated by 1 MeV Kr ions up to 1.80E16 ions/cm2. At this energy, few Kr ions will be deposited within the lamellae, only creating radiation damages and consequent enhanced diffusion in those pre-implanted U-10Zr lamellae. The Xe bubbles formed in irradiated TEM lamellae will be characterized by Fresnel edges in underfocus-overfocus TEM images. The size distribution and number density of both intragranular and intergranular Xe bubbles will be measured from the TEM images taken at different doses and in various phases. The results will provide precious experimental results for the model optimization and validation of the advanced fuel performance code for U-10Zr metallic fuel in fast reactors. The in situ TEM ion irradiation investigation takes one days for each sample. As there will be ten samples (five irradiation temperatures and as-fabricated/pre-implanted), we request ten (10) days of IVEM-Tandem facility time. |
| Award Announced Date | 2018-02-01T14:16:13.21 |
| Awarded Institution | Center for Advanced Energy Studies |
| Facility | Microscopy and Characterization Suite |
| Facility Tech Lead | Alina Zackrone, Wei-Ying Chen, Yaqiao Wu |
| Irradiation Facility | None |
| PI | Yinbin Miao |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1226 |