Study of Pore Modality of Irradiated UO2 Fuel Assembly

2017 ◽  
Vol 727 ◽  
pp. 693-697
Author(s):  
Yan Hua Peng ◽  
Fei Wang ◽  
Wei Zhu ◽  
Yan Jiang ◽  
Hong Kui Tang ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Fuel Assembly ◽  
High Performance ◽  
Local Area ◽  
Transgranular Crack ◽  
Fuel Pellets ◽  
Micro Cracks ◽  
Fission Gas ◽  
Main Factors ◽  
Irradiated Fuel

UO2 fuel pellets may be swelling and recrystallization during irradiation. Density, dimension and distribution of pores are main factors to induce irradiation swelling, especially the size distribution of pellet pores plays an important role. 4×4-4 fuel assembly was a high performance fuel assembly which was self-designed and manufactured, the average burn-up of the fuel assembly was 42GWd/tU.For studying the effect of irradiation on pore modality, the specimens of irradiated UO2 fuel pellets were taken from 4×4-4 fuel assembly after dismantling, microscopic structure and distribution of pores for UO2 fuel assembly by scanning electron microscopy were studied in this paper. The results showed that there were many cracks in fuel pellets, most micro-cracks were transgranular crack. The release rate of fission gas with burn up were augmentation, which was consistent with the porosity of diversity burp up fuel rod. Pores were distributed non-uniformly in irradiated fuel pellets, gathered at local area and more obvious connectivity of pores. The size of pores after the irradiation was between 0.2~1.2 μm, and mostly distributed at 0.3μm ~0.6 μm; The pores at grain boundary of two adjacent grains was less, the pores at grain boundary were distributed by the way of triangle or quadrilateral. The size of pores was increased than pre-irradiation, but ratio of pores and density of pores were decreased obviously, the phenomenon of irradiation densification was occurred in fuel pellets after irradiated. Recrystallization and Rim structure effect were not found.

Precision grain Boundary Engineering in commercial Bi2Te2.7Se0.3 thermoelectric materials towards high performance

2021 ◽  
Author(s):  
Shuankui Li ◽  
Zhongyuan Huang ◽  
Rui Wang ◽  
Chaoqi Wang ◽  
Wenguang Zhao ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Thermoelectric Materials ◽  
High Performance ◽  
General Strategy ◽  
Grain Boundary Engineering

The strong interrelation between electrical and thermo parameters have been regarded as one of the biggest bottlenecks to obtain high-performance thermoelectric materials. Therefore, to explore a general strategy to fully...

A novel economical grain boundary engineered ultra-high performance ZnO varistor with lesser dopants

2018 ◽  
Vol 38 (15) ◽  
pp. 5021-5029 ◽  
Author(s):  
K. Hembram ◽  
T.N. Rao ◽  
M. Ramakrishna ◽  
R.S. Srinivasa ◽  
A.R. Kulkarni
Keyword(s):  
Grain Boundary ◽  
High Performance ◽  
Zno Varistor

Micro Electrical Discharge Machining Thermal Effect on Micro-Cracks Generation on Silicon Material

2021 ◽  
Vol 1047 ◽  
pp. 41-49
Author(s):  
Xiao Zhong Song
Keyword(s):  
Electrical Discharge Machining ◽  
Crystalline Silicon ◽  
Local Area ◽  
Silicon Wafers ◽  
Adverse Side Effect ◽  
Micro Edm ◽  
Crystalline Orientation ◽  
Surface Machining ◽  
Crack Generation ◽  
Micro Cracks

Various novel 3D micro machining technologies were researched and developed for silicon micro mechanical system fabrication. Micro EDM is one of them. The material removal mechanism is thermal sparking erosion and is completely independent with regards to the crystalline orientation of silicon, therefore there is no orientation constraint in processing the complex 3D geometry of silicon wafers. As thermal sparking implied, the process features local area high temperature melting and evaporating, and this characteristic has an adverse side-effect on the sparked surface integrity. One important concern is the generation of micro cracks, which would provide an adverse effect on the fatigue life of the micro feature element made of silicon. For this consideration, in this paper, with the experiment and SEM picture analysis approach, the author explored the micro crack generation characteristics on mono crystalline silicon wafers under micro EDM with available sparking energies and on the different crystal orientation surface machining. The generation of micro cracking is not only related with the sparking energy but also related with the crystalline orientation. The {100} orientation is the strongest surface to resist crack generation. For a strong-doped P type silicon wafer, there exists a maximum crack energy threshold. If single sparking energy is over this threshold, micro cracks unavoidably would be generated on any orientation surface. Two types of chemical etching post processes that can remove cracks on sparked surfaces are also tested and discussed.

Grain Subdivision Fission Gas Swelling Model for UO2

MRS Advances ◽  
2016 ◽  
Vol 1 (35) ◽  
pp. 2465-2470
Author(s):  
Thomas Winter ◽  
Richard Hoffman ◽  
Chaitanya S. Deo
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Gas Diffusion ◽  
Fine Grain ◽  
Fuel Pellets ◽  
Model And Simulation ◽  
Nucleation Sites ◽  
Fission Gas ◽  
High Burnup ◽  
Swelling Model

ABSTRACTUnder high burnup UO2 fuel pellets can experience high burnup structure (HBS) at the rim also known as rim effect. The HBS is exceptionally porous with fine grain sizes. HBS increases the swelling further than it would have achieved at a larger grain size. A theoretical swelling model is used in conjunction with a grain subdivision simulation to calculate the swelling of UO2. In UO2 the nucleation sites are at vacancies and the bubbles are concentrated at grain boundaries. Vacancies are created due to irradiation and gas diffusion is dependent on vacancy migration. In addition to intragranular bubbles, there are intergranular bubbles at the grain boundaries. Over time as intragranular bubbles and gas atoms accumulate on the grain boundaries, the intergranular bubbles grow and cover the grain faces. Eventually they grow into voids and interconnect along the grain boundaries, which can lead to fission gas release when the interconnection reaches the surface. This is known as the saturation point. While the swelling model used does not originally incorporate a changing grain size, the simulation allows for more accurate swelling calculations by introducing a fractional HBS based on the temperature and burnup of the pellet. The fractional HBS is introduced with a varying grain size. Our simulations determine the level of swelling and saturation as a function of burnup by combining an independent model and simulation to obtain a more comprehensive model.

A HIGH-PERFORMANCE MIXED-TECHNOLOGY LAN FOR EDUCATION AND RESEARCH

2001 ◽  
Vol 12 (04) ◽  
pp. 459-467
Author(s):  
CLAUDIO D. ARLANDINI ◽  
MATTEO J. BOSCHINI ◽  
ANDREA MATTASOGLIO
Keyword(s):  
High Performance ◽  
Local Area Networks ◽  
Local Area ◽  
Full Duplex ◽  
Effective Bandwidth ◽  
Performance Tests ◽  
Mass Storage ◽  
Network Systems ◽  
High Bandwidth ◽  
University Consortium

In this work we describe a series of performance tests on different architectures of high bandwidth local area networks, contemporarily in use at C.I.L.E.A. (Inter-University Consortium for Automatic Elaboration of Lombardy) to connect multi-processor machines devoted to educational and research purposes, such as fluido-dynamic and mechanical simulations. This LAN is essentially made out of a standard FDDI ring, and an HyperFabric backbone. HyperFabric is a Hewlett-Packard high performance network system bus, with a declared maximum bandwidth of 2.5 Gbit/s full duplex per link. We present a comparison, in terms of effective bandwidth, average throughput and CPU consumption of the above mentioned network systems. Furthermore we also describe the effects, in terms of transfer efficiency, of such a mixed environment, in which different systems co-exist and must often be cross-walked by various applications, as backups and mass storage access. Measurements and comparisons are made using Open Software tools like netperf and HetPIPE.

scholarly journals Correction: Consolidating the grain boundary of the garnet electrolyte LLZTO with Li3BO3 for high-performance LiNi0.8Co0.1Mn0.1O2/LiFePO4 hybrid solid batteries

2019 ◽  
Vol 7 (36) ◽  
pp. 20965-20965 ◽  
Author(s):  
Huilin Xie ◽  
Chunli Li ◽  
Wang Hay Kan ◽  
Maxim Avdeev ◽  
Chenyou Zhu ◽  
...  
Keyword(s):  
Grain Boundary ◽  
High Performance

Correction for ‘Consolidating the grain boundary of the garnet electrolyte LLZTO with Li3BO3 for high-performance LiNi0.8Co0.1Mn0.1O2/LiFePO4 hybrid solid batteries’ by Huilin Xie et al., J. Mater. Chem. A, 2019, DOI: 10.1039/c9ta03263k.

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