scholarly journals Uniformity Assessment of TRISO Fuel Particle Distribution in Spherical HTGR Fuel Element Using Voronoi Tessellation and Delaunay Triangulation

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Libing Zhu ◽  
Xincheng Xiang ◽  
Yi Du ◽  
Gongyi Yu ◽  
Ziqiang Li ◽  
...  
Keyword(s):  
Fuel Element ◽  
Delaunay Triangulation ◽  
Nearest Neighbor ◽  
Voronoi Tessellation ◽  
Fission Products ◽  
Fuel Particle ◽  
Volume Distribution ◽  
Triso Fuel ◽  
Triso Particles ◽  
Log Normal

Nonuniform distribution of tri-structural-isotropic (TRISO) fuel particles in a spherical fuel element (SFE) may increase the failure probability of the SFE in the high-temperature gas-cooled reactor, leading to the release of fission products. To evaluate the uniformity of the TRISO particles nondestructively, 3-dimensional cone-beam computed tomography is used to image the SFE, and TRISO particles are segmented. After TRISO particle positions are identified, the Voronoi tessellation and Delaunay triangulation are used to extract several geometric metrics. Results indicate that both the Voronoi volume distribution and the nearest neighbor-distance distribution follow the log-normal distributions, which provide strong evidence that the TRISO particles are approximately randomly uniformly distributed. Further study will be focused on validating the conclusion with more SFE data.

Reactivity Hold-Down Technique for a Soluble Boron Free PWR Using TRISO Particle Fuel

2013 ◽  
Author(s):  
Xiang Dai ◽  
Xinrong Cao
Keyword(s):  
Nuclear Proliferation ◽  
Reactor Core ◽  
Fission Products ◽  
Fuel Kernel ◽  
Average Temperature ◽  
Fuel Rod ◽  
Triso Fuel ◽  
Coated Particle ◽  
Graphite Matrix ◽  
Triso Particles

TRISO coated particle, developed for HTGR initially, has advantages of nuclear proliferation-resistance and fuel integrity against the release of fission products. In this paper, a 350MWt small sized PWR core design utilizing TRISO fuel concept is presented. TRISO particles are dispersed in graphite matrix to form the fuel compact, and then the fuel compact is clad by Zircaloy-4 cladding to form a fuel rod. The graphite matrix increases thermal conductivity of fuel compact, so that the fuel average temperature would be well below conventional PWRs’. In order to simplify reactor design, operation and maintenance, soluble boron free concept while operation is introduced. The emphasis of the study is put on the reactivity hold-down technique for the 350MWt PWR core. Excess reactivity is suppressed through a combination of Pu-240 adding with Gd2O3 loading. Pu-240 is added into UO2 fuel kernel of some assemblies, and Gd2O3 rods are loaded in other assemblies. The non-fissile plutonium isotope Pu-240 has a considerably high thermal neutron capture cross section compared to U-238, so that the Pu-240 added fuel can greatly suppress excess reactivity over burnup. Besides, reactor core life would be extended by adding proper amount of Pu-240 for its converting into Pu-241 which is a fissile isotope. Combining Pu-240 adding with Gd2O3 loading, the designed core reaches an average core burnup of approximately 58GWD/t, as well as a core life of nearly 6EFPY.

Thermodynamic Modelling of the Uranium-Carbon-Oxygen System in the Frame of the Uranium Oxide and Carbon Interaction in the TRISO Fuel Particle of High Temperature Reactor

2006 ◽  
Vol 45 ◽  
pp. 1944-1951 ◽  
Author(s):  
Jean Christophe Dumas ◽  
Jean Paul Piron ◽  
Sylvie Chatain ◽  
Christine Guéneau
Keyword(s):  
High Temperature ◽  
Fission Products ◽  
Nuclear Materials ◽  
Chemical Compositions ◽  
Fuel Particle ◽  
Chemical Systems ◽  
Triso Fuel ◽  
Physico Chemical ◽  
Chemical Studies ◽  
Fuel Particles

A thermodynamic approach is necessary in order to predict and understand physico-chemical phenomena occurring in nuclear materials under irradiation, involving large chemical systems with a lot of elements including both initial nuclides and fission products (FP). In the frame of thermo-chemical studies of the High Temperature Reactors fuel, a first step is to assess the (U-O-C) system in order to understand the interaction between the UO2 kernel and the pyrocarbon layers constituting such a fuel particle. Our model for irradiated oxide fuel, based on Lindemer’s analysis, has been improved by introducing the (U-O-C) model developed by C. Guéneau & al into the SAGE code. Chemical compositions and related carbon oxides pressures of irradiated TRISO fuel particles have been calculated with the data published by Minato & al. We discuss our results by comparison with their thermochemical calculations and with their experimental observations. This approach can be used to predict the behaviour of complex nuclear materials, especially for the different kind of fuel materials considered in the frame of Gas Fast Reactors.

scholarly journals TRISO Fuel Performance Modelling with BISON

2021 ◽  
Vol 2048 (1) ◽  
pp. 012012
Author(s):  
B Collin ◽  
W Jiang ◽  
K Gamble ◽  
R Gardner ◽  
J Hales ◽  
...  
Keyword(s):  
Failure Mechanisms ◽  
Fission Products ◽  
Performance Modelling ◽  
Fuel Performance ◽  
New Developments ◽  
Triso Fuel ◽  
Coated Particle ◽  
Diffusion Parameters ◽  
Triso Particles ◽  
Fractional Release

Abstract Modeling of tristructural isotropic (TRISO)-coated particle fuel is being refined in the fuel performance code BISON. New developments include the implementation of an updated set of material properties, TRISO failure mechanisms, fission product diffusion parameters, and the design of a Monte Carlo scheme that allows BISON to calculate the probability of fuel failure within a population of TRISO particles and the subsequent fractional release of key fission products.

scholarly journals Evaluation of Oxidation Performance of TRISO Fuel Particles for Postulated Air-Ingress Accident of HTGR

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Fangcheng Cao ◽  
De Zhang ◽  
Qingjie Chen ◽  
Hao Li ◽  
Hongqing Wang
Keyword(s):  
Reaction Rates ◽  
Good Oxidation Resistance ◽  
Triso Fuel ◽  
Rate Determining Step ◽  
Parabolic Law ◽  
Oxidation Performance ◽  
Triso Particles ◽  
Fuel Particles ◽  
Air Ingress ◽  
High Temperature Gas

In a high-temperature gas-cooled reactor, the integrity of tristructural-isotropic-(TRISO-) coated fuel particles ensures the safety of the reactor, especially in case of an air-ingress accident. The oxidation of TRISO particles with the outer layers of silicon carbide (SiC) was performed at temperatures of 900°C–1400°C in air environment. Both the microstructure and phase composition of the SiC layers were studied. The results showed that the SiC layers had a good oxidation resistance below 1100°C. However, the amorphous silica on the SiC layers formed at 1200°C and gradually crystallized at 1400°C with the presence of microcracks. The reaction rates of the SiC layers were determined by measuring the silica thickness. It was proposed that the oxidation of the SiC layers followed the linear-parabolic law with the activation energy of 146 ± 5 kJ/mol. The rate-determining step of the oxidation was the diffusion of oxygen in silica.

Effect of PyC Thermal Behavior on the Stress of TRISO-Coated Fuel Particles

2016 ◽  
Vol 697 ◽  
pp. 852-857
Author(s):  
Rong Li ◽  
Bing Liu ◽  
Chun He Tang
Keyword(s):  
Pressure Vessel ◽  
Elastic Strain ◽  
Fission Products ◽  
Fuel Particle ◽  
Coated Particles ◽  
Inner Pressure ◽  
Higher Temperature ◽  
Fuel Particles ◽  
Coated Fuel Particle ◽  
Increasing Temperature

TRISO coated fuel particle is the most important component in HTR fuel, the silicon carbide (SiC) coating layer is regarded as the pressure vessel to contain the fission products. During reactor operation, the inner pressure resulting from fission products and pyrocarbon (PyC) thermal effect will contribute to the failure of TRISO-coated particles. The higher temperature will result in the increasing of inner pressure and PyC thermal expansion, which will then change the stress of SiC layer. Considering the effects of temperature on inner-pressure expansion and elastic strain into the pressure vessel failure model, thermal effects on the stress of TRISO-coated particles were studied with analytical solution. The results indicated that the effects of inner pressure on the particle stresses were increasingly highlighted at the late stage of irradiation. And the increasing temperature caused a slight effect on PyC elastic modulus while elastic strain is unaffected greatly, either. Therefore, CFP stresses remain unchanged basically.

Understanding the 1600°C Fuel Temperature Limit of TRISO Coated Fuel Particles

2015 ◽  
Vol 1769 ◽  
Author(s):  
Félix Cancino Trejo ◽  
Mariana Sáenz Padilla ◽  
Eddie López-Honorato
Keyword(s):  
Fission Products ◽  
Chemical Vapor ◽  
Pyrolytic Carbon ◽  
Temperature Limit ◽  
Inert Atmosphere ◽  
Effect Of Temperature ◽  
Fuel Particle ◽  
Fuel Temperature ◽  
Water Reactors ◽  
Coated Fuel Particle

ABSTRACTThe TRISO (tristructural isotropic) coated fuel particle is made of a uranium oxide kernel coated with three layers of pyrolytic carbon and one of silicon carbide. This fuel, originally used in High Temperature Reactors, has been proposed as accident tolerant fuel for Light Water Reactors after the accident in Fukushima. Although this fuel is capable of retaining fission products within the particle up to 1600°C, little is known on the origin of this temperature limit. Therefore, in order to increase the safety of this type of fuel, it is necessary to understand the origin of the degradation of the materials that compose this fuel. We have studied the effect of temperature on the microstructure and diffusion of silver in pyrolytic carbon coatings produced by fluidized bed chemical vapor deposition. Samples were heat treated at 1000°C, 1400°C and 1700°C for 200 hrs. under inert atmosphere. The effect of temperature on the microstructure and silver diffusion behavior were analyzed by Raman spectroscopy, X-Ray diffraction, optical microscopy, SEM and TEM. We observed that the microstructure of PyC changed drastically above 1400°C, showing the increase in anisotropy and the re-orientation of the graphene planes. The diffusion of silver appears to be also correlated with this change in microstructure.

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