NSUF 18-1144: In situ investigation of the thermomechanical performance of HCP metals and Zircaloy-4 under ion beam irradiation
In recent years, significant advances have been made in the use of ion beams to emulate the type of radiation-induced microstructural evolution expected as a result of long-term neutron exposure. However, most radiation damage studies using ion beams still rely on the same types of post-irradiation examination as has been used for decades with neutron-irradiated material, namely destructive mechanical testing and electron microscopy, to quantify the effects of a given exposure. While some in situ methods exist for studying material properties and structure during irradiation, for example TEM or Raman spectroscopy, there is no commonly used method to directly measure the thermal and mechanical properties of materials continuously throughout an irradiation. Data of this character, thermomechanical performance in beam-on conditions, on structural and component materials used in reactor systems, are extremely important for safe system operation. Recently, a non-destructive photoacoustic technique known as transient grating spectroscopy (TGS) has been developed for this purpose. Through the all-optical, non-contact induction and monitoring of surface acoustic waves (SAWs) on materials under investigation, the thermal diffusivity and the elastic constants of the material in question may be determined using measurements on the order of seconds. In the fall of 2017, an in situ ion beamline test facility at Sandia National Labs is being constructed through which concurrent ion beam irradiation and TGS monitoring of material performance may be accomplished. Prior post-irradiation testing of self-ion irradiated copper has shown that TGS has the ability to detect radiation-induced microstructural evolution, in that case volumetric void swelling, in exposed materials. This new experimental capability is poised to be leveraged as a powerful tool for materials testing. This project seeks to use this new capability, located on the 6 MV tandem accelerator at the Sandia Ion Beam Lab, to study the performance of Zircaloy-4 under high-temperature, self-ion irradiation. Using this facility, we will be able to directly assess the performance of this reactor cladding material at relevant operational temperatures (300-400C) while defect production is ongoing. However, to be able to study the HCP zirconium alloys in greatest detail, we will first study pure single crystal and then polycrystalline titanium, as a model HCP metal, to best inform the data collected on Zircaloy-4. Previous studies of irradiated materials using TGS have all been on cubic materials, necessitating the use of a model system to prepare for a textured HCP engineering alloy. In all irradiations, high energy (30-40 MeV) self ions will be used to match the imposed damage profile with the micron-scale mechanical actuation depth imposed using TGS. Given the dose rates achievable on the tandem accelerator at the IBL, we intend to reach total doses of up to 150 dpa in some Zircaloy samples. Finally, we also plan on using the high-temperature sample stage present on the in situ TGS experiment to induce a temperature excursion, simulating LOCA conditions, at a point where a Zircaloy-4 sample has reached half of its operational lifetime equivalent dose. Such a test would provide critical material performance characteristics of interest to many currently operating reactors.
Additional Info
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| Abstract | In recent years, significant advances have been made in the use of ion beams to emulate the type of radiation-induced microstructural evolution expected as a result of long-term neutron exposure. However, most radiation damage studies using ion beams still rely on the same types of post-irradiation examination as has been used for decades with neutron-irradiated material, namely destructive mechanical testing and electron microscopy, to quantify the effects of a given exposure. While some in situ methods exist for studying material properties and structure during irradiation, for example TEM or Raman spectroscopy, there is no commonly used method to directly measure the thermal and mechanical properties of materials continuously throughout an irradiation. Data of this character, thermomechanical performance in beam-on conditions, on structural and component materials used in reactor systems, are extremely important for safe system operation. Recently, a non-destructive photoacoustic technique known as transient grating spectroscopy (TGS) has been developed for this purpose. Through the all-optical, non-contact induction and monitoring of surface acoustic waves (SAWs) on materials under investigation, the thermal diffusivity and the elastic constants of the material in question may be determined using measurements on the order of seconds. In the fall of 2017, an in situ ion beamline test facility at Sandia National Labs is being constructed through which concurrent ion beam irradiation and TGS monitoring of material performance may be accomplished. Prior post-irradiation testing of self-ion irradiated copper has shown that TGS has the ability to detect radiation-induced microstructural evolution, in that case volumetric void swelling, in exposed materials. This new experimental capability is poised to be leveraged as a powerful tool for materials testing. This project seeks to use this new capability, located on the 6 MV tandem accelerator at the Sandia Ion Beam Lab, to study the performance of Zircaloy-4 under high-temperature, self-ion irradiation. Using this facility, we will be able to directly assess the performance of this reactor cladding material at relevant operational temperatures (300-400C) while defect production is ongoing. However, to be able to study the HCP zirconium alloys in greatest detail, we will first study pure single crystal and then polycrystalline titanium, as a model HCP metal, to best inform the data collected on Zircaloy-4. Previous studies of irradiated materials using TGS have all been on cubic materials, necessitating the use of a model system to prepare for a textured HCP engineering alloy. In all irradiations, high energy (30-40 MeV) self ions will be used to match the imposed damage profile with the micron-scale mechanical actuation depth imposed using TGS. Given the dose rates achievable on the tandem accelerator at the IBL, we intend to reach total doses of up to 150 dpa in some Zircaloy samples. Finally, we also plan on using the high-temperature sample stage present on the in situ TGS experiment to induce a temperature excursion, simulating LOCA conditions, at a point where a Zircaloy-4 sample has reached half of its operational lifetime equivalent dose. Such a test would provide critical material performance characteristics of interest to many currently operating reactors. |
| Award Announced Date | 2018-09-17T00:00:00 |
| Awarded Institution | Argonne National Laboratory |
| Facility | Intermediate Voltage Electron Microscopy (IVEM)-Tandem Facility |
| Facility Tech Lead | Michael Starr, Wei-Ying Chen |
| Irradiation Facility | None |
| PI | Michael Short |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1144 |