Fuel Pellet from Oil Producing Plants

ABSTRACTA fuel leaching experiment has been in progress since 1977 to study the dissolution behaviour of used CANDU fuel in aerated aqueous solution. The experiment involves exposure of 50-mm clad segments of an outer element of a Pickering fuel bundle (burnup 610 GJ/kg U; linear and peak power ratings 53 and 58 kW/m, respectively), to deionized distilled water (DDH2O, ∼2 mg/L carbonate) and tapwater (∼50 mg/L carbonate). In 1992, it was observed that the fuel in at least one of the leaching solutions showed some signs of deterioration and, therefore, in 1993, parts of the fuel samples were sacrificed for a detailed analysis of the physical state of the fuel, using SEM and optical microscopy. Leaching results to date show that even after >6900 days only 5 to 7.7% of the total calculated inventory of 137Cs has leached out preferentially and that leach rates suggest a development towards congruent dissolution. Total amounts of 137Cs and 90Sr leached are slightly larger in tapwater than in DDH2O. SEM examinations of leached fuel surface fragments indicate that the fuel surface exposed to DDH2O is covered in a needle-like precipitate. The fuel surface exposed to tapwater shows evidence of leaching but no precipitate, likely because uranium is kept in solution by carbonate. Detailed optical and SEM microscopy examinations on fuel cross sections suggest that grain-boundary dissolution in DDH2O is not prevalent, and in tapwater appears to be limited to the outer %0.5 mm (pellet/cladding) region of the fuel. Grain boundary attack seems to be limited to microcracks at or near the surface of the fuel. It thus appears that grain-boundary attack occurs only near the fuel pellet surface and is prevalent only in the presence of carbonate in solution.

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Modeling the Irradiation Swelling of UO2 at the Fuel Pellet Rim

Volume 1: Plant Operations, Maintenance, Engineering, Modifications, Life Cycle and Balance of Plant; Nuclear Fuel and Materials; Radiation Protection and Nuclear Technology Applications ◽

10.1115/icone21-15009 ◽

2013 ◽

Author(s):

Lijun Gao ◽

Bingde Chen ◽

Zhong Xiao ◽

Shengyao Jiang ◽

Jiyang Yu

Keyword(s):

Pore Size ◽

Fission Products ◽

Transformation Process ◽

Fuel Pellet ◽

Published Data ◽

Detailed Calculation ◽

Pore Density ◽

The Matrix ◽

Swelling Rate ◽

Modeling Code

Irradiation swelling of UO2 at the fuel pellet rim was modeled based on the published theory and data of HBS (High Burnup Structure) formation. Fuel swelling was divided into two parts: fuel matrix swelling and porosity growth. Both solid fission products and fission gas contribute to the fuel matrix swelling prior to HBS transformation, resulting in relatively stable matrix swelling rate of around 1.0% per 10 GWd/tU, but the transformation accompanied by Xe depletion reduces the matrix swelling rate to approximately 0.3% per 10 GWd/tU, only attributed to solid fission products. Considering the direct impact of Xe depletion on the drop of matrix swelling rate, the exponential law of Xe depletion was applied to model the reduction of matrix swelling rate. Pore size and pore density evolution are the two main aspects of porosity growth. Pore size takes the form of lognormal distribution, whose parameters are obtained through fitting the experimental data. Pore density increases in the transformation process but goes down as a result of pore coarsening thereafter. Published data of three pellets were used to verify the correlations modeling pore growth, which were proven generally consistent with each other. The results of this work are ready to be incorporated into fuel performance modeling code as an option for detailed calculation of fuel swelling.

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Pellet-Cladding Interaction of LMFBR Fuel Elements at Unsteady State: An Introduction to Computer Code ISUNE-5

Journal of Engineering for Power ◽

10.1115/1.3230785 ◽

1981 ◽

Vol 103 (4) ◽

pp. 627-636 ◽

Cited By ~ 1

Author(s):

B. M. Ma

Keyword(s):

Reactor Core ◽

Fatigue Cracking ◽

Computer Code ◽

Fuel Burnup ◽

Fuel Pellet ◽

Gas Release ◽

Unsteady State ◽

Fission Gas ◽

Fuel Elements ◽

Fission Gas Release

The fuel pellet-cladding interaction (PCI) of liquid-metal fast breeder reactor (LMFBR) fuel elements or fuel rods at unsteady state is analyzed and discussed based on experimental results. In the analyses, the heat generation, fuel restructuring, temperature distribution, gap conductance, irradiation swelling, irradiation creep, fuel burnup, fission gas release, fuel pellet cracking, crack healing, cladding cracking, yield failure and fracture failure of the fuel elements are taken into consideration. To improve the sintered (U,Pu)O2 fuel performance and reactor core safety at high temperature and fuel burnup, it is desirable to (a) increase and maintain the ductility of cladding material, (b) provide sufficient gap thickness and plenum space for accommodating fission gas release, (c) keep ramps-power increase rate slow and gentle, and (d) reduce the intensity and frequency of transient PCI in order to avoid intense stress fatigue cracking (SFC) and stress corrosion cracking (SCC) due to fission product compounds CsI, CdI2, Cs2Te, etc. at the inner cladding surface of the fuel elements during PCI.

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Properties of the high burnup structure in nuclear light water reactor fuel

Radiochimica Acta ◽

10.1515/ract-2017-2831 ◽

2017 ◽

Vol 105 (11) ◽

Cited By ~ 7

Author(s):

Thierry Wiss ◽

Vincenzo V. Rondinella ◽

Rudy J. M. Konings ◽

Dragos Staicu ◽

Dimitrios Papaioannou ◽

...

Keyword(s):

Mechanical Properties ◽

Nuclear Fuel ◽

Experimental Studies ◽

Fuel Pellet ◽

Extended Defects ◽

Safety Margins ◽

Fission Gas ◽

High Burnup ◽

Formed Structure

AbstractThe formation of the high burnup structure (HBS) is possibly the most significant example of the restructuring processes affecting commercial nuclear fuel in-pile. The HBS forms at the relatively cold outer rim of the fuel pellet, where the local burnup is 2–3 times higher than the average pellet burnup, under the combined effects of irradiation and thermo-mechanical conditions determined by the power regime and the fuel rod configuration. The main features of the transformation are the subdivision of the original fuel grains into new sub-micron grains, the relocation of the fission gas into newly formed intergranular pores, and the absence of large concentrations of extended defects in the fuel matrix inside the subdivided grains. The characterization of the newly formed structure and its impact on thermo-physical or mechanical properties is a key requirement to ensure that high burnup fuel operates within the safety margins. This paper presents a synthesis of the main findings from extensive studies performed at JRC-Karlsruhe during the last 25 years to determine properties and behaviour of the HBS. In particular, microstructural features, thermal transport, fission gas behaviour, and thermo-mechanical properties of the HBS will be discussed. The main conclusion of the experimental studies is that the HBS does not compromise the safety of nuclear fuel during normal operations.

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Preparation and Characterization of Sawdust Derived Bio-Fuel Pellets Depending on "Solid Bridge" Intertwining Action of Hyacinth Fiber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.878.450 ◽

2014 ◽

Vol 878 ◽

pp. 450-458

Author(s):

Ling Jun Kong ◽

Xiong Fei Zhang ◽

Shuang Hong Tian ◽

Ting Liu ◽

Ya Xiong

Keyword(s):

Mechanical Properties ◽

Room Temperature ◽

Elastic Recovery ◽

Impact Resistance ◽

Resistance Index ◽

Cost Effective ◽

Environmental Benefits ◽

Fuel Pellet ◽

Mass Ratio ◽

Solid Bridge

Densified biomass pellets named as H/S-BPs were prepared from waste wood sawdust (S) in the presence of water hyacinth fiber (H) as solid bridge under room temperature and 6 MPa lower than in the previous study. Mechanical properties including relaxed density (ρr), resiliency (R), abrasion resistance (AR) and impact resistance index (IRI) were evaluated. Results showed that adding H greatly reduced negative effect of resiliency on the mechanical properties of H/S-BPs during storage. For example, H/S-BPs compressed at 6 MPa in an H/S mass ratio of 1 to 3 presented lower resiliency of 10% and higher relaxed density of 1.04 kg dm-3 than pellets without H fiber. This is due to the intertwining action of H fiber, what fabricates solid bridge, replacing the bonding creating by applying high pressure to resist the disruptive force caused by elastic recovery. Thus, compression of waste H and S in a mass ratio of 1 to 3 at room temperature under 6 MPa is a cost-effective process to produce densified sustainable bio-fuel pellet as well as dispose waste S and H, combining the economical and environmental benefits.

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Neutronic Analysis of Accident-Tolerant Fuel Assemblies With Silicon Carbide Cladding in Pressurized Water Reactors

Volume 9: Student Paper Competition ◽

10.1115/icone25-66744 ◽

2017 ◽

Cited By ~ 1

Author(s):

Zhixiong Tan ◽

Jiejin Cai

Keyword(s):

Silicon Carbide ◽

Fuel Assembly ◽

Power Distribution ◽

Safety Margin ◽

Severe Accident ◽

Pressurized Water Reactors ◽

Fuel Pellet ◽

Pressurized Water ◽

Neutronic Parameters ◽

Water Reactors

After Fukushima Daiichi Nuclear Power Plant accident, alternative fuel-design to enhance tolerance for severe accident conditions becomes particularly important. Silicon carbide (SiC) cladding fuel assembly gain more safety margin as novel accident tolerant fuel. This paper focuses on the neutron properties of SiC cladding fuel assembly in pressurized water reactors. Annular fuel pellet was adopted in this paper. Two types of silicon carbide assemblies were evaluated via using lattice calculation code “dragon”. Type one was consisted of 0.057cm SiC cladding and conventional fuel. Type two was consisted of 0.089cm SiC cladding and BeO/UO2 fuel. Compared the results of SiC cladding fuel assembly neutronic parameters with conventional Zircaloy cladding fuel assembly, this paper analyzed the safety of neutronic parameters performance. Results demonstrate that assembly-level reactivity coefficient is kept negative, meanwhile, the numerical value got a relatively decrease. Other parameters are conformed to the design-limiting requirement. SiC kinds cladding show more flat power distribution. SiC cases also show the ability of reducing the enrichment of fuel pellets even though it has higher xenon concentration. These types of assembly have broadly agreement neutron performance with the conventional cladding fuel, which confirmed the acceptability of SiC cladding in the way of neutron physics analysis.

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Thermodynamic descriptions of oxygen redistribution in a nuclear fuel pellet: Heat of transport of oxygen in mixed conductors

Journal of Applied Electrochemistry ◽

10.1007/bf00254150 ◽

1994 ◽

Vol 24 (5) ◽

Cited By ~ 7

Author(s):

M. Kamata ◽

T. Esaka

Keyword(s):

Nuclear Fuel ◽

Fuel Pellet ◽

Mixed Conductors ◽

Heat Of Transport

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Sensitivity of the neutron multiplication factor to water ingress into a spent fuel cask

Kerntechnik ◽

10.1515/kern-2020-850107 ◽

2020 ◽

Vol 85 (1) ◽

pp. 38-53

Author(s):

M. J. Leotlela ◽

I. Petr ◽

A. Mathye

Keyword(s):

Gradual Increase ◽

Primary Objective ◽

Fuel Pellet ◽

Main Body ◽

Spent Fuel ◽

Reactivity Effect ◽

Water Ingress ◽

Accident Scenarios ◽

The Impact ◽

Gain Access

Abstract An essential component of safety analyses is the investigation of accident scenarios. In this paper water ingress scenarios of spent fuel containers, as they may occur during transport or storage, are examined. In the main body of this paper, a number of paths are studied through which water can gain access to the spent fuel cask and eventually reach the fuel pellet, potentially resulting in an increase in reactivity as a result of over-moderation. The primary objective of this project was to perform an assessment of what, in the unlikely event of a Fukushima- type accident, the impact would be on the reactivity of the cask by analyzing a gradual increase in water level in the spent fuel casks. In addition, the way the keff of the system responds to such an increase is discussed. The paper also provides the results of an assessment of the reactivity effect of water ingress via various pathways/channels.

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