Abstract
As an alternative fuel form, the annular metallic fuel design eliminates the liquid sodium bond between the fuel and the cladding, providing back-end fuel cycle and other benefits. The fuel-cladding chemical interaction (FCCI) of annular fuel also presents new features. Here, state-of-the-art electron microscopy and spectroscopy techniques were used to study the FCCI of a prototype annular U-10wt%Zr (U-10Zr) fuel with ferritic/martensitic HT-9 cladding irradiated to 3.3% fission per initial heavy atom. Compared with sodium-bonded solid fuels, negligible amounts of lanthanides were found in the FCCI layer in the investigated helium-bonded annular fuel. Instead, most lanthanides were retained in the newly formed UZr2 phase in the fuel center region. The interdiffusion of iron and uranium resulted in tetragonal (U,Zr)6Fe phase (space group I4/mcm) and cubic (U,Zr)(Fe,Cr)2 phase (space group Fd3¯m). The (U,Zr)(Fe,Cr)2phase contains a high density of voids and intergranular uranium monocarbides of NaCl-type crystal structure (space group Fm3¯m). At the interdiffusion zone and inner cladding interface, a porous lamellar structure composed of alternating Cr-rich layers and U-rich layers was observed. Next to the lamellar region, the unexpected phase transformation from body-centered cubic ferrite (α-Fe) to tetragonal binary Fe-Cr σ phase (space group P42/mnm) occurred, and tetragonal Fe-Cr-U-Si phase (space group I4/mmm) was identified. Due to the diffusion of carbon into the interdiffusion zone, carbon depletion inside the HT-9 led to the disappearance of the martensite lath structure, and intergranular U-rich carbides formed as a result of the diffusion of uranium into the cladding. These detailed new findings reveal the unique features of the FCCI behavior of annular U-Zr fuels, which could be a promising alternative fuel form for high burnup fast reactor applications.
| Original language | English |
|---|---|
| Article number | 152588 |
| Journal | Journal of Nuclear Materials |
| Volume | 544 |
| DOIs | |
| State | Published - Feb 2021 |
Funding
X. Liu acknowledges the financial support from the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DEAC07-051D14517 as part of a Nuclear Science User Facilities. T. Yao and L. He acknowledge the support from the Center for Thermal Energy Transport under Irradiation, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. This work was supported by the Advanced Fuels Campaign (AFC) of the Nuclear Technology Research and Development (NTRD) program in the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07-05ID14517. Accordingly, the U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript or allow others to do so, for U.S. Government purposes.
| Funders | Funder number |
|---|---|
| Center for Thermal Energy Transport | |
| Nuclear Technology Research and Development | DE-AC07-05ID14517 |
| U.S. Government | |
| U.S. Department of Energy | DEAC07-051D14517 |
| Office of Science | |
| Office of Nuclear Energy | |
| Basic Energy Sciences |
Keywords
- Advanced nuclear fuel
- Fuel-cladding chemical interaction (FCCI)
- HT-9 cladding
- Metallic fuel
- Phase transformation
- Transmission electron microscopy (TEM)