EPMA and TEM Characterization of a UO2 fuel pellet and cladding interaction layer
Principal Investigator
- Name:
- Sarah Finkeldei
- Email:
- nsuf@inl.gov
- Phone:
- (208) 526-6918
Team Members:
| Name: | Institution: | Expertise: | Status: |
|---|---|---|---|
| B Sutton | |||
| P Chou | |||
| Mahmut Cinbiz | Oak Ridge National Laboratory | nuclear materials, radiation effects, hydriding, Zirconium alloys | Post Doc |
| Arunodaya Bhattacharya | Oak Ridge National Laboratory | will provide guidance for analytical S/TEM analysis | Post Doc |
| Lingfeng He | Idaho National Laboratory | microstructural characterization, nuclear fuels, TEM, radiation effects, Ceramics | Other |
| Karen Wright | Idaho National Laboratory | Electron Probe Microanalysis (EPMA) | Other |
Experiment Details:
- Experiment Title:
- EPMA and TEM Characterization of a UO2 fuel pellet and cladding interaction layer)
- Hypothesis:
- We hypothesize that the local mechanical conditions during RIA are effected by the microstructure of the brittle interaction layer and the high burn-up fuel in the close proximity. Therefore, we propose to analyze the interaction layer and the high burn-up fuel structure by EPMA and analytical S/TEM, the knowledge of which is currently highly limited in the literature. These experiments will elucidate the complex nature of pellet cladding interaction micro-mechanisms during RIA.
- Work Description:
- The irradiated North Anna fuel sample consists of UO2 fuel with a Zr-Nb alloy cladding. There is a sample readily available at INL’s Hot Fuel Examination Facility for EPMA analysis. Four specimens from the North Anna high burn-up nuclear fuel (two from the fuel as well as the fuel cladding interface regions) will be prepared using a dual beam focused ion beam (FIB) for characterization by analytical S/TEM. The FEI Titan chemi-S/TEM with a four quadrant EDS will be used for microstructural characterization including the elemental mapping and quantification.
Project Summary
During operation of a nuclear power plant, a brittle complex oxide layer evolves between the UO2 fuel and the cladding material. There is limited knowledge on this generated interaction layer (U-Zr-O) in particular on its irradiation-induced microstructural evolution. The interaction layer acts as a buffer for the pellet-cladding interaction, in particular during the pellet-cladding mechanical interaction (PCMI) phase of reactivity initiated accidents (RIA) where the expanding fuel imposes mechanical loading on the cladding. The microstructure of the brittle interaction layer and the high burn-up fuel in the close proximity, are expected to affect the nature of the local mechanical loading conditions. A detailed characterization of the interaction layer in a high burn-up fuel will lead to an improved mesoscale understanding of the complex phenomena occurring during RIA. Thus, we propose to study the interaction layer and the high burn-up fuel structure by EPMA and analytical S/TEM. The derived data will be beneficial for the mesoscale model development at the interlayer of high burn-up fuel and cladding.
Relevance
The overarching goal of this proposal is to increase the scientific knowledge on the nuclear fuel performance in nuclear power plants which is a key DOE/NE mission. The Light Water Reactor Sustainability program and the Advanced Fuels Campaign of DOE/NE specifically seek to improve the scientific knowledge to predict fuel rod performance in nuclear power plants. The specific interest of this proposal is to characterize the interaction layer between the UO2 fuel and the cladding which plays a key role during the design basis transients of nuclear reactors. Thus, we expect that the characterization of the interaction layer will support the activities towards the design of TREAT experiments. Characterization of the high burn-up fuel is one of the key research topics, and their characterization provides insightful knowledge on the current and future fuel developments for a safe nuclear fuel cycle. Thus, a detailed characterization of the high burn-up fuel cladding interaction layer by EPMA and analytical S/TEM meet the DOE missions on several programs as specified by DOE’s nuclear agenda.