scholarly journals Neutronics feasibility of using Gd₂O₃ particles in VVER-1000 fuel assembly

2016 ◽  
Vol 6 (3) ◽  
pp. 1-7
Author(s):  
Van Khanh Hoang ◽  
Phi Hung Hoang Thanh ◽  
Hoai Nam Tran
Keyword(s):  
Thermal Conductivity ◽  
Fuel Assembly ◽  
High Power ◽  
Power Distribution ◽  
Fuel Pellet ◽  
Power Peak ◽  
Calculation Results ◽  
Fuel Pin ◽  
High Burnup ◽  
Power Densities

Neutronics feasibility of using Gd2O3 particles for controlling excess reactivity of VVER-1000 fuel assembly has been investigated. The motivation is that the use of Gd2O3 particles would increase the thermal conductivity of the UO2+Gd2O3 fuel pellet which is one of the desirable characteristics for designing future high burnup fuel. The calculation results show that the Gd2O3 particles with the diameter of 60 µm could control the reactivity similarly to that of homogeneous mixture with the same amount of Gd2O3. The power densities at the fuel pin with Gd2O3 particles increase by about 10-11%, leading to the decrease of the power peak and a slightly flatter power distribution. The power peak appears at the periphery pins at the beginning of burnup process which is decreased by 0.9 % when using Gd2O3 particles. Further work and improvement are being planned to optimize the high power peaking at the beginning of burnup.

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

2017 ◽  
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.

Cost Saving When Using Enhanced Conductivity Nuclear Fuel Containing BeO in WWER-1000 Reactors

2014 ◽  
Author(s):  
Tomáš Zahrádka ◽  
Radek Škoda
Keyword(s):  
Thermal Conductivity ◽  
Nuclear Fuel ◽  
Fuel Pellet ◽  
Internal Stresses ◽  
Fuel Temperature ◽  
Pressurized Water ◽  
Adverse Conditions ◽  
Advantages And Disadvantages ◽  
Fuel Pin ◽  
Water Reactors

Current pressurized water reactors utilize sintered UO2 that has a number of advantages and disadvantages. Uranium Dioxide’s low thermal conductivity results in a large thermal gradient within the fuel pellet corresponding to higher centerline temperatures compared to other potential fuel forms. These gradients result in non-uniform thermal expansion leading to large internal stresses resulting in cracking of the pellet and fuel-clad interaction, which can lead to loss of the integrity of the fuel pin. Higher fuel temperatures also increase the release of fission gases. Fuels with higher thermal conductivity may alleviate or reduce the severity of these adverse conditions. It is shown that higher thermal conductivity can be obtained by adding BeO to the basic UO2 matrix. This paper focuses on WWER1000 hexagonal fuel geometry. Improvements when using 10% of BeO, as proposed in this paper, reduce the centerline nuclear fuel temperature by 234°C and improve the fuel economy while reducing its cost by 7%. The study was done for NPP Temelín which has two units WWER1000/320.

scholarly journals Power Distribution and Possible Influence on Fuel Failure in WWER-1000

2008 ◽  
Vol 2008 ◽  
pp. 1-5
Author(s):  
Ján Mikuš
Keyword(s):  
Experimental Data ◽  
Fuel Assembly ◽  
Power Distribution ◽  
Power Reactor ◽  
Construction Materials ◽  
Static Loads ◽  
Fission Rate ◽  
Light Water ◽  
Fuel Failure ◽  
Fuel Pin

The work is focused on the influence of investigation of some core heterogeneities and construction materials on the space power (fission rate) distribution in WWER-1000-type cores, especially from viewpoint of the values and gradient occurrence that could result in static loads with some consequences, for example, fuel pin (FP) or fuel assembly (FA) bowing and possible contribution to the FP failure root causes. For this purpose, experimental data and their analysis from two earlier performed measurements on light water, zero-power reactor LR-0 were used, concerning the relative radial power distribution determined by measurements in a WWER-1000-type core containing single FPs with homogeneous gadolinium admixture () and the relative radial power distribution determined by measurements in FA situated on the periphery of a WWER-1000-type core neighbouring the baffle (thermal shielding).

The Effects of Material Properties on Heat Dissipation in High Power Electronics

1998 ◽  
Vol 120 (3) ◽  
pp. 280-289 ◽  
Author(s):  
T. J. Lu ◽  
A. G. Evans ◽  
J. W. Hutchinson
Keyword(s):  
Thermal Conductivity ◽  
Power Electronics ◽  
High Power ◽  
Heat Dissipation ◽  
Substrate Material ◽  
High Thermal Conductivity ◽  
Analytical Models ◽  
Wide Range ◽  
Power Densities

The role of the substrate in determining heat dissipation in high power electronics is calculated, subject to convective cooling in the small Biot number regime. Analytical models that exploit the large aspect ratio of the substrate to justify approximations are shown to predict the behavior with good accuracy over a wide range of configurations. The solutions distinguish heat spreading effects’ that enable high chip-level power densities from insulation effects that arise at large chip densities. In the former, the attributes of high thermal conductivity are apparent, especially when the substrate dimensions are optimized. Additional benefits that derive from a thin layer of a high thermal conductivity material (such as diamond) are demonstrated. In the insulating region, which arises at high overall power densities, the substrate thermal conductivity has essentially no effect on the heat dissipation. Similarly, for compact multichip module designs, with chips placed on both sides of the substrate, heat dissipation is insensitive to the choice of the substrate material, unless advanced cooling mechanisms are used to remove heat around the module perimeter.

Thermal conductivity evaluation of high burnup mixed-oxide (MOX) fuel pellet

2011 ◽  
Vol 414 (2) ◽  
pp. 303-308 ◽  
Author(s):  
Masaki Amaya ◽  
Jinichi Nakamura ◽  
Fumihisa Nagase ◽  
Toyoshi Fuketa
Keyword(s):  
Thermal Conductivity ◽  
Mixed Oxide ◽  
Fuel Pellet ◽  
Mox Fuel ◽  
High Burnup

Thermal Conductivity Change in High Burnup MOX Fuel Pellet

2009 ◽  
Vol 46 (9) ◽  
pp. 944-952 ◽  
Author(s):  
Jinichi NAKAMURA ◽  
Masaki AMAYA ◽  
Fumihisa NAGASE ◽  
Toyoshi FUKETA
Keyword(s):  
Thermal Conductivity ◽  
Fuel Pellet ◽  
Conductivity Change ◽  
Mox Fuel ◽  
High Burnup

Burnable Poison Design for Supercritical Water Cooled Reactor With Annular Fuel

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Zhao Chuanqi ◽  
Wang Kunpeng ◽  
Cao Liangzhi ◽  
Zheng Youqi
Keyword(s):  
Rare Earth ◽  
Fuel Assembly ◽  
Supercritical Water ◽  
Power Distribution ◽  
Rare Earth Oxide ◽  
Burnable Poison ◽  
The Core ◽  
Power Peak ◽  
Supercritical Water Cooled Reactor ◽  
Control Rods

Burnable poison (BP) is used to control excess reactivity in supercritical water cooled reactor (SCWR). It helps reduce the number of control rods. Over all BP designs, the design in which rare-earth oxide mixes with fuel is widely used in SCWR. BP has influence on fuel assembly neutronics performance. After comparing four kinds of rare-earth oxide, Er2O3 is chosen as BP for the annular fuel assembly. The effect of different BP loading patterns on assembly power distribution is analyzed. The safety of annular fuel assembly is estimated with different BP contents. Core performance with and without BP is compared. The results had shown that the core radial power peaking factor decreased after introducing BP. It was also shown that the core axial power peaking factor increased, and the power peak moved toward the top of the core. The reason of this effect was studied. Two optimizations were given based on this study: decreasing the temperature of lower plenum and increasing the gradients of axial enrichments. By applying these optimizations, core axial power peaking factor and maximum cladding surface temperature decreased.

Analysis on Impact of Fuel Thermal Conductivity Degradation (TCD) on Large Break Loss of Coolant Accidents of CAP1000

2017 ◽  
Author(s):  
Wang Weiwei ◽  
Lu Lu
Keyword(s):  
Thermal Conductivity ◽  
Nuclear Power ◽  
Power Plants ◽  
Sensitivity Study ◽  
Fuel Pellet ◽  
Steady State Condition ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant ◽  
Fuel Storage ◽  
High Burnup

Under high burnup conditions, thermal conductivity of fuel pellet degrades, which is referred to as thermal conductivity degradation (TCD). TCD phenomenon influences fuel average temperature and fuel storage energy under steady state condition before loss of coolant accident (LOCA) and further influences peak cladding temperature (PCT) during large break LOCA process. In this study, sensitivity study on double ended guillotine break of cold leg in CAP1000 at different burnup conditions was performed, using large break LOCA analysis code WCOBRA/TRAC and PCTs under different conditions were obtained. The modified NFI (Nuclear Fuels Institute) TCD model was adopted to model fuel conductivity after degradation in analysis and decrease of peaking factors including FQ and FΔh after 30GWD/MTU was also considered. Sensitivity analysis showed that: after considering the influence of TCD and peaking factor burndown, the PCT limiting case did not occur in low burnup range again, but occurred at burup of about 29GWD/MTU. Compared to other burnup points, the first and second peak values of PCT at that burnup point were all at the highest level. Performing of this study could prefer reference for analysis and estimation of large break LOCA of passive nuclear power plants under high burnup conditions.

scholarly journals Multiphysics Model Development and the Core Analysis for In Situ Breeding and Burning Reactor

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Shengyi Si
Keyword(s):  
Power Distribution ◽  
Model Development ◽  
Computer Code ◽  
Ceramic Composites ◽  
Fuel Pellet ◽  
Ceramic Pellet ◽  
Sic Ceramic ◽  
Calculation Results ◽  
Gen Iv

The in situ breeding and burning reactor (ISBBR), which makes use of the outstanding breeding capability of metallic pellet and the excellent irradiation-resistant performance of SiCf/SiC ceramic composites cladding, can approach the design purpose of ultralong cycle and ultrahigh burnup and maintain stable radial power distribution during the cycle life without refueling and shuffling. Since the characteristics of the fuel pellet and cladding are different from the traditional fuel rod of ceramic pellet and metallic cladding, the multiphysics behaviors in ISBBR are also quite different. A computer code, named TANG, to model the specific multiphysics behaviors in ISBBR has been developed. The primary calculation results provided by TANG demonstrate that ISBBR has an excellent comprehensive performance of GEN-IV and a great development potential.

scholarly journals KYLIN-V2.0 CODE CALCULATION ABILITY VERIFICATION BASED ON VERA BENCHMAR

2021 ◽  
Vol 247 ◽  
pp. 10020
Author(s):  
Dongyong Wang ◽  
Yingrui Yu ◽  
Xingjie Peng ◽  
Chenlin Wang ◽  
Kun Liu ◽  
...  
Keyword(s):  
Fuel Assembly ◽  
Power Distribution ◽  
Nuclear Power ◽  
Neutron Transport ◽  
Monte Carlo Code ◽  
Neutron Transport Equation ◽  
Control Rod ◽  
Fuel Assemblies ◽  
Fuel Pin ◽  
Calculation Ability

Virtual Environmental for Reactor Analysis (VERA) benchmark was released by the Consortium for Advanced Simulation of Light water reactors (CASL) project in 2012. VERA benchmark includes more than ten problems at different levels, from 2D fuel pin case to 2D fuel assembly case to 3D core refuelling case, in addition, reference results and experimental measured data of some problems were provided by CASL. Fuel assemblies in VERA benchmark are various, including control rod assemblies, Pyrex assembly, IFBA assembly, WABA assembly and gadolinium poison assembly, and so on. In this paper, various fuel assembly models in the VERA benchmark have been built by using KYIIN-V2.0 code to verify its calculation ability from 2D fuel pin case to 2D fuel assembly case to 2D 3x3 fuel assembly case, and making a comparative analysis on the reference results in VERA benchmark, as well as the calculation results of the Monte Carlo code RMC. KYLIN-V2.0 is an advanced neutron transport lattice code developed by Nuclear Power Institute of China (NPIC). The subgroup resonance calculation method is used in KYIIN-V2.0 to obtain effective resonance selfshielding cross section, method of modular characteristics (MOC) is adopted to solve the neutron transport equation, and CRAM method and PPC method is adopted to solve the depletion equation. The numerical results show that KYLIN-V2.0 code has the reliable capability of direct heterogeneous calculation of 2D fuel assembly, and the effective multiplication factor, assembly power distribution, rod power distribution and control rod reactivity worths of various fuel assemblies that are calculated by KYLIN-V2.0 are in better agreement with the reference.

Sign in / Sign up

Export Citation Format

Share Document