NSUF 18-1457: Microstructural Modifications in U-10Zr Irradiated by High-Energy Xe Ions
Gaseous fission products such as Xe and Kr form bubbles within nuclear fuel materials during operation. The fission gas bubbles compromise the fuel performance by causing gaseous swelling, degrading thermal conductivity, and eventually initiating fission gas release. 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. Thus, quantitative information such as the size distribution and number density of both types of bubbles is crucial to predicting the degradation of bulk fuel properties by these microstructural modifications. In advanced fast reactor concepts, higher burnup needs to be achieved in comparison to light water reactors (LWRs). Thus, a different strategy of fission gas management is suggested. Thus, instead of prevention of fission gas release in LWR fuels, fission gas release in fast reactor fuels needs to be facilitated to relieve fuel-cladding interaction due to fuel swelling. Moreover, from 600C to 750C, which falls into the range of fuel operating temperatures in faster reactors, U-10Zr has five different phase domains. As a results, fission gas behaviors in all those U-Zr phases must be studied. Therefore, the investigations on the fission gas behavior are much more complex than conventional UO2 fuels. Although a series of in-pile irradiation experiments have been performed for U-10Zr and similar class of metallic fuels, the detailed microstructure information of fission gas bubble morphology in various U-Zr phases have not been unveiled due to the high financial cost and significant technical difficulties coupled with the post-irradiation examinations (PIEs) of in-pile irradiated fuel materials. Fortunately, ion irradiation can work as an inexpensive complementary method to in-pile irradiation to study radiation effects in materials. In particular, for nuclear fuel materials, when high-energy (~100 MeV level) fission product ions are used, the actual energetic fission fragments (which cause the majority of the radiation-induced microstructural modifications in real nuclear fuels) can be replicated using a powerful accelerator. Hence, this proposed project aims to take advantage of the efficiency and economy of high-energy ion irradiation to produce valuable experimental references (focus on detailed microstructure information of bubbles in different phases) for the ongoing development of advanced fuel performance models to evaluate U-10Zr and similar class of metallic fuels in advanced fast reactors. Along with the Thus, along with the abundant experimental data available from previous in-pile irradiation experiments (macroscopic swelling strain measurement, phase division observation, Zr redistribution, etc.), the advance fuel performance codes for U-10Zr can be optimized and validated. Accordingly, five U-10Zr samples irradiated by 84 MeV Xe ions to 1.60×1017 ions/cm-2 at 600°C, 650°C, 675°C, 700°C, and 750°C, respectively, will be investigated along with an as-received (control) sample. The irradiation temperatures cover the all five phase domains of U-10Zr, whereas the irradiation dose provides a peak Xe concentration equivalent to 10%FIMA. A TEM lamellae will be prepared from each sample using FIB. The TEM lamellae will be investigated to establish the morphology, size distribution, and number density of Xe bubbles in different U-Zr phase (correlated with different irradiation temperature). The results of this proposed project will help facilitate modeling efforts supported by the NEAMS-FPL program by providing quantitative microstructural information of fission gas bubbles for model optimization, parameterization, and validation. As the majority of the FIB preparation will be done at Argonne at no cost at NSUF, only final FIB thinning and cleaning will be conducted at MaCS in CAES. FIB sample preparation will take two (2) days; TEM examination will take four (8) days, 1 day for each TEM sample (5 irradiated samples + 1 control sample) and 2 extra day for looking into details for two samples that are most interesting. The total time required is within the RTE proposal limitation.
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 compromise the fuel performance by causing gaseous swelling, degrading thermal conductivity, and eventually initiating fission gas release. 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. Thus, quantitative information such as the size distribution and number density of both types of bubbles is crucial to predicting the degradation of bulk fuel properties by these microstructural modifications. In advanced fast reactor concepts, higher burnup needs to be achieved in comparison to light water reactors (LWRs). Thus, a different strategy of fission gas management is suggested. Thus, instead of prevention of fission gas release in LWR fuels, fission gas release in fast reactor fuels needs to be facilitated to relieve fuel-cladding interaction due to fuel swelling. Moreover, from 600C to 750C, which falls into the range of fuel operating temperatures in faster reactors, U-10Zr has five different phase domains. As a results, fission gas behaviors in all those U-Zr phases must be studied. Therefore, the investigations on the fission gas behavior are much more complex than conventional UO2 fuels. Although a series of in-pile irradiation experiments have been performed for U-10Zr and similar class of metallic fuels, the detailed microstructure information of fission gas bubble morphology in various U-Zr phases have not been unveiled due to the high financial cost and significant technical difficulties coupled with the post-irradiation examinations (PIEs) of in-pile irradiated fuel materials. Fortunately, ion irradiation can work as an inexpensive complementary method to in-pile irradiation to study radiation effects in materials. In particular, for nuclear fuel materials, when high-energy (~100 MeV level) fission product ions are used, the actual energetic fission fragments (which cause the majority of the radiation-induced microstructural modifications in real nuclear fuels) can be replicated using a powerful accelerator. Hence, this proposed project aims to take advantage of the efficiency and economy of high-energy ion irradiation to produce valuable experimental references (focus on detailed microstructure information of bubbles in different phases) for the ongoing development of advanced fuel performance models to evaluate U-10Zr and similar class of metallic fuels in advanced fast reactors. Along with the Thus, along with the abundant experimental data available from previous in-pile irradiation experiments (macroscopic swelling strain measurement, phase division observation, Zr redistribution, etc.), the advance fuel performance codes for U-10Zr can be optimized and validated. Accordingly, five U-10Zr samples irradiated by 84 MeV Xe ions to 1.60×1017 ions/cm-2 at 600°C, 650°C, 675°C, 700°C, and 750°C, respectively, will be investigated along with an as-received (control) sample. The irradiation temperatures cover the all five phase domains of U-10Zr, whereas the irradiation dose provides a peak Xe concentration equivalent to 10%FIMA. A TEM lamellae will be prepared from each sample using FIB. The TEM lamellae will be investigated to establish the morphology, size distribution, and number density of Xe bubbles in different U-Zr phase (correlated with different irradiation temperature). The results of this proposed project will help facilitate modeling efforts supported by the NEAMS-FPL program by providing quantitative microstructural information of fission gas bubbles for model optimization, parameterization, and validation. As the majority of the FIB preparation will be done at Argonne at no cost at NSUF, only final FIB thinning and cleaning will be conducted at MaCS in CAES. FIB sample preparation will take two (2) days; TEM examination will take four (8) days, 1 day for each TEM sample (5 irradiated samples + 1 control sample) and 2 extra day for looking into details for two samples that are most interesting. The total time required is within the RTE proposal limitation. |
| Award Announced Date | 2018-05-17T11:12:00.113 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Yinbin Miao |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1457 |