NSUF 19-1789: Radiation Stability Study on Nuclear Waste Materials
Radiation damage and decay heat are significant issues for nuclear waste and spent fuel storage. The purpose of our study is to evaluate the long-term radiation stability of nuclear waste materials, as the material is subjected to self-radiation damage and elevated temperature due to decay heat. The principal sources of radiation in high level waste are beta-decay of the fission products (e.g., 137Cs and 90Sr) and alpha-decay of the actinide elements (e.g., U, Np, Pu, Am, and Cm). During nuclear waste storage, helium (He) atoms will accumulate as a result of the capture of two electrons by alpha-particles, and He concentration will increase with cumulative dose from alpha-decay events. At increased concentrations, it may form bubbles, which can cause swelling, microcracking and affect many of the physical properties of the nuclear waste materials. He implantation is an effective tool for understanding alpha-particle effects; similarly, heavy-ion (e.g., Kr) irradiation is an effective method to study alpha-recoil effects. In this investigation, we propose to implant He and irradiate Kr ions simultaneously or sequentially to study the synergistic effect in single phase nuclear waste materials including hollandite (A2+B3+2C4+6O16), powellite (A2+B6+O4), oxyapatite (A2Ln8Si6O26) phases, and borosilicate glass. We are interested in radiation-induced swelling and microcracking in these crystalline phases as a function of temperature. During our previous IVEM experiments, we have systematically investigated the ion irradiation-induced amorphization as a function of temperature in Cr-hollandite (BaCs0.3Cr2.3Ti5.7O16) and other hollandites with various compositions. In our bulk ion implantation experiments at Los Alamos National Laboratory, we observed He irradiation-induced microcracking and volume swelling in multiphase nuclear waste forms, especially in hollandite phase. The proposed work at the IVEM-Tandem Facility at Argonne National Laboratory, is to examine the synergistic effect of He and Kr irradiations described above via in-situ transmission electron microscopy (in-situ TEM using the Hitachi H-9000 TEM) while irradiating with 1.0 MeV Kr++ and 5-20 keV He ions simultaneously or sequentially. The focus will be on irradiation-induced lattice swelling and microcracking in nuclear waste materials. Ion irradiations will be used to simulate self-radiation in nuclear wastes or spent fuels. The choice of ion mass and energy will ensure that the majority of Kr ions pass all the way through the TEM thin foil and He ions stay in the sample, so that any radiation damage effects observed can be attributed to He accumulation and alpha-particle/recoil effects. Radiation damage effects will be investigated over the temperature range of room temperature to 300 °C which is close to storage temperature.
Additional Info
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|---|---|
| Abstract | Radiation damage and decay heat are significant issues for nuclear waste and spent fuel storage. The purpose of our study is to evaluate the long-term radiation stability of nuclear waste materials, as the material is subjected to self-radiation damage and elevated temperature due to decay heat. The principal sources of radiation in high level waste are beta-decay of the fission products (e.g., 137Cs and 90Sr) and alpha-decay of the actinide elements (e.g., U, Np, Pu, Am, and Cm). During nuclear waste storage, helium (He) atoms will accumulate as a result of the capture of two electrons by alpha-particles, and He concentration will increase with cumulative dose from alpha-decay events. At increased concentrations, it may form bubbles, which can cause swelling, microcracking and affect many of the physical properties of the nuclear waste materials. He implantation is an effective tool for understanding alpha-particle effects; similarly, heavy-ion (e.g., Kr) irradiation is an effective method to study alpha-recoil effects. In this investigation, we propose to implant He and irradiate Kr ions simultaneously or sequentially to study the synergistic effect in single phase nuclear waste materials including hollandite (A2+B3+2C4+6O16), powellite (A2+B6+O4), oxyapatite (A2Ln8Si6O26) phases, and borosilicate glass. We are interested in radiation-induced swelling and microcracking in these crystalline phases as a function of temperature. During our previous IVEM experiments, we have systematically investigated the ion irradiation-induced amorphization as a function of temperature in Cr-hollandite (BaCs0.3Cr2.3Ti5.7O16) and other hollandites with various compositions. In our bulk ion implantation experiments at Los Alamos National Laboratory, we observed He irradiation-induced microcracking and volume swelling in multiphase nuclear waste forms, especially in hollandite phase. The proposed work at the IVEM-Tandem Facility at Argonne National Laboratory, is to examine the synergistic effect of He and Kr irradiations described above via in-situ transmission electron microscopy (in-situ TEM using the Hitachi H-9000 TEM) while irradiating with 1.0 MeV Kr++ and 5-20 keV He ions simultaneously or sequentially. The focus will be on irradiation-induced lattice swelling and microcracking in nuclear waste materials. Ion irradiations will be used to simulate self-radiation in nuclear wastes or spent fuels. The choice of ion mass and energy will ensure that the majority of Kr ions pass all the way through the TEM thin foil and He ions stay in the sample, so that any radiation damage effects observed can be attributed to He accumulation and alpha-particle/recoil effects. Radiation damage effects will be investigated over the temperature range of room temperature to 300 °C which is close to storage temperature. |
| Award Announced Date | 2019-05-14T17:00:57.62 |
| Awarded Institution | Center for Advanced Energy Studies |
| Facility | Microscopy and Characterization Suite |
| Facility Tech Lead | Wei-Ying Chen, Yaqiao Wu |
| Irradiation Facility | None |
| PI | Ming Tang |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1789 |