scholarly journals Using FRAPTRAN 1.5 code for safety evaluation of TVS-2006 fuel rod under transient conditions of VVER-1200 (AES-2006) reactor

2015 ◽  
Vol 5 (3) ◽  
pp. 44-55
Author(s):  
Ngoc Diep Do ◽  
Khac Toan Phung
Keyword(s):  
Fuel Element ◽  
Safety Evaluation ◽  
Oxide Thickness ◽  
Stress And Strain ◽  
Mechanical Parameters ◽  
Analysis Program ◽  
Transient Conditions ◽  
Fuel Rod ◽  
Loss Of Coolant ◽  
Good Agreement

This article shows the results of important thermal-mechanical parameters related to the TVS-2006 fuel rod design which were analyzed and evaluated by using FRAPTRAN1.5 code. Based on the data given in the Preliminary Safety Analysis Report (PSAR) of AES-2006 (Novovoronezh NPP-2 Power Unit No.1)and FRAP-T (Fuel Rod Analysis Program-Transient), FRAPTRAN1.5 calculations of TVS-2006 fuel rod behaviors in Loss of Coolant Accidents and Reactivity-Initiated Accidents conditions have been made. The calculated results related to safety criteria of fuel element and cladding temperatures, cladding stress and strain, fuel enthalpy, local oxide thickness, gap gas pressure, and elongation of fuel rod have been compared with the ones given in AES-2006 PSAR. A good agreement has been observed between AES-2006 PSAR andFRAPTRAN1.5 calculations.

scholarly journals A CFD analysis of blockage length on a partially blocked fuel rod

2019 ◽  
Vol 7 (2B) ◽  
Author(s):  
Nikolas Lymberis Scuro ◽  
Pedro Ernesto Umbehaun ◽  
Edvaldo Angelo ◽  
Gabriel Angelo ◽  
Delvonei Alves de Andrade
Keyword(s):  
Steady State ◽  
Hydraulic Properties ◽  
Temperature Drop ◽  
Cfd Analysis ◽  
Fuel Rods ◽  
Transient Conditions ◽  
Fuel Rod ◽  
Loss Of Coolant Accident ◽  
Ansys Cfx ◽  
Loss Of Coolant

After a loss of coolant accident (LOCA), fuel rods may balloon. The swelling can partially block the flow channel, affecting the coolability during reflood phase. In order to analyze the influence of blockage length, using a radial blockage of 90%, varying just the blockage length, many steady state numerical simulations has been done using Ansys-CFX code to verify thermal-hydraulic properties according to different forced cooled conditions. Temperature peaks are observed on cladding, followed by a temperature drop. A 5x5 fuel assembly, with 9 centered ballooned fuel rod, flow redistribution inside channels can also be captured, indicating an overheating zone. Therefore, this study conclude, for the same boundary conditions, the longer the blockage length originated after LOCA events, the higher are the clad temperatures, indicating the possibility of overheat during transient conditions on reflood.

scholarly journals Development of Thermal Models and Analysis of UO2-BeO Fuel during a Loss of Coolant Accident

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Deepthi Chandramouli ◽  
Shripad T. Revankar
Keyword(s):  
Thermal Conductivity ◽  
Temperature Drop ◽  
Specific Enthalpy ◽  
Performance Parameters ◽  
Transient Conditions ◽  
Fuel Rod ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant ◽  
Gas Gap ◽  
Lower Temperature

Small fraction of high conductivity BeO in UO2 fuel significantly improves thermal conductivity and also affects the overall performance of the fuel during steady state operation and during transients. In this study, performance of UO2-BeO composite under transient conditions such as loss of coolant accident (LOCA), using FRAPTRAN (fuel rod analysis program transient), was carried out. The subroutines in FRAPTRAN code that calculate key thermophysical properties such as thermal conductivity, specific heat capacity, and specific enthalpy were modified to account for the presence of the BeO in UO2. The fuel performance parameters like gas gap pressure, energy stored in fuel, and temperature profiles were studied. The simulation results showed reductions in fuel centerline temperatures and lower temperature drop across fuel rod cross-section under normal fuel operations. It was observed that there was reduction in gas gap pressure and energy stored in fuel. Transient conditions involving cladding rupture were investigated and important performance parameters such as cladding strain were studied. During these transients, the addition of BeO to UO2 fuel seems beneficiary.

An Analytical Drain Current Model for Dual-material Gate Graded - channel and Dual-oxide Thickness Cylindrical Gate (DMG-GC-DOT) MOSFET

2019 ◽  
Vol 9 (2) ◽  
pp. 291-297
Author(s):  
Hind Jaafar ◽  
Abdellah Aouaj ◽  
Ahmed Bouziane ◽  
Benjamin Iñiguez
Keyword(s):  
Current Model ◽  
Drain Current ◽  
Oxide Thickness ◽  
Subthreshold Current ◽  
The Poisson Equation ◽  
Strong Inversion ◽  
Cylindrical Form ◽  
Silvaco Atlas ◽  
Dual Material ◽  
Good Agreement

Background: A novel Dual Material Gate Graded Channel and Dual Oxide Thickness Cylindrical Gate (DMG-GC-DOT) MOSFET is presented in this paper. Methods: Analytical model of drain current is developed using a quasi-two-dimensional cylindrical form of the Poisson equation and is expressed as a function of the surface potential, which is calculated using the expressions of the current density. Results: Comparison of the analytical results with 3D numerical simulations using Silvaco Atlas - TCAD software presents a good agreement from subthreshold to strong inversion regime and for different bias voltages. Conclusion: Two oxide thicknesses with different permittivity can effectively improve the subthreshold current of DMG-GC-DOT MOSFET.

Investigation of Quench-16 Experiment With MELCOR Computer Code

2014 ◽  
Author(s):  
Petya Vryashkova ◽  
Pavlin Groudev ◽  
Antoaneta Stefanova
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Initial Temperature ◽  
Computer Code ◽  
Air Flow Rate ◽  
Fuel Rod ◽  
Fuel Bundle ◽  
Oxygen Starvation ◽  
Air Ingress ◽  
Good Agreement

This paper presents a comparison of MELCOR calculated results with experimental data for the QUENCH-16 experiment. The analysis for the air ingress experiment QUENCH-16 has been performed by INRNE. The calculations have been performed with MELCOR code. The QUENCH-16 experiment has been performed on 27-th of July 2011 in the frame of the EC-supported LACOMECO program. The experiments have focused on air ingress investigation into an overheated core following earlier partial oxidation in steam. QUENCH-16 has been performed with limited pre-oxidation and low air flow rate. One of the main objectives of QUENCH-16 was to examine the interaction between nitrogen and oxidized cladding during a prolonged period of oxygen starvation. The bundle is made from 20 heated fuel rod simulators arranged in two concentric rings and one unheated central fuel rod simulator, each about 2.5 m long. The tungsten heaters were surrounded by annular ZrO2 pellets to simulate the UO2 fuel. The geometry and most other bundle components are prototypical for Western-type PWRs. To improve the obtained results it has been made a series of calculations to select an appropriate initial temperature of the oxidation of the fuel bundle and modified correlation oxidation of Zircaloy with MELCOR computer code. The compared results have shown good agreement of calculated hydrogen and oxygen starvation in comparison with test data.

scholarly journals Hysteretic Behavior of Geopolymer Concrete with Active Confinement Subjected to Monotonic and Cyclic Axial Compression: An Experimental Study

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3997 ◽  
Author(s):  
Huailiang Wang ◽  
Yuhui Wu ◽  
Min Wei ◽  
Lang Wang ◽  
Baoquan Cheng
Keyword(s):  
Failure Modes ◽  
Peak Stress ◽  
Hysteretic Behavior ◽  
Stress And Strain ◽  
Geopolymer Concrete ◽  
Cement Concrete ◽  
Cyclic Compression ◽  
Stress States ◽  
Loading Modes ◽  
Good Agreement

This paper investigated the performance of actively confined geopolymer concrete (GPC) through experiments. The mechanical properties of GPC under triaxial stress states were analyzed and discussed from the prospects of failure modes, axial peak stress and strain, monotonic and cyclic constitutive relationships. The experimental results demonstrated that the loading modes (monotonic loading and cyclic loading) had little effect on the failure mode and axial peak stress and strain. The improvement of the strength and ductility of GPC with the increase in confinement level was consistent with that of the conventional cement concrete while the strain enhancement of confined GPC was lower than that of confined conventional cement concrete at the same confinement level. The curves of the monotonic stress–strain and the envelop of cyclic compression were predicted through Mander’s model with good accuracy. The unloading/reloading models proposed by Lokuge were modified and the predicted cyclic hysteresis curves for actively confined GPC were in good agreement with the cyclic compression results. Findings from this study provide references for the application of geopolymer concrete.

The Research on Core Melting Process: Oxidation

2013 ◽  
Author(s):  
Jun Wang ◽  
Wenxi Tian ◽  
Jianan Lu ◽  
Yingying Ma ◽  
Guanghui Su ◽  
...  
Keyword(s):  
Natural Circulation ◽  
Reactor Core ◽  
Melting Process ◽  
Coolant Pump ◽  
Fuel Rod ◽  
Fuel Pellets ◽  
Design Basis ◽  
Loss Of Coolant ◽  
Design Basis Accident ◽  
Station Blackout

Beyond-design basis accidents in the AP1000 may result in reactor core melting and are therefore termed core melt accidents. The aim of this work is to develop a code to calculate and analyze the oxidation of a single fuel rod with total failures of engineered safeguard systems under a certain beyond-design basis accident such as a gigantic earthquake which can result in station blackout and then total loss of coolant flow. Using the code, the responses of the most dangerous fuel rod in the AP1000 were calculated under the accident. A discussion involving fuel pellets melting, cladding rupture and oxidation, and hydrogen production then was carried out, focused on DNBR during coolant pump coastdown, the cladding intactness under different flow rates in natural circulation, and the delay effect on cladding rupture due to cladding oxidation. By the analysis of calculated results, several suggestions on guaranteeing the security of fuel rods were provided.

Effect of deformation and loss-of-seal on the embrittlement of VVER fuel-element cladding in loss-of-coolant accidents

Atomic Energy ◽  
2008 ◽  
Vol 104 (5) ◽  
pp. 355-359 ◽  
Author(s):  
V. P. Deniskin ◽  
D. N. Ignat’ev ◽  
V. S. Konstantinov ◽  
V. I. Nalivaev ◽  
D. M. Soldatkin ◽  
...  
Keyword(s):  
Fuel Element ◽  
Fuel Element Cladding ◽  
Vver Fuel ◽  
Loss Of Coolant

Effect of Creep on Stress and Strain at the Tip of Stress Corrosion Cracking in High Temperature Water Environments

2014 ◽  
Vol 494-495 ◽  
pp. 651-654
Author(s):  
He Xue ◽  
Jin Tian ◽  
Fu Qiang Yang
Keyword(s):  
High Temperature ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Stress And Strain ◽  
Mechanical Parameters ◽  
High Temperature Water ◽  
High Pressure Environment ◽  
Temperature Water

Stress and strain at the crack tip are main mechanical parameters which estimate the stress corrosion cracking rate in metals, and the creep of metals in high temperature and high pressure environment will lead to the redistribution of stress and strain nearby the crack tip. The effects of creep on stress and strain nearby the crack tip are discussed by using 1T-CT specimen and finite element method in this study. The investigated results indicate that both increasing of temperature and stress intensity factor would induce the equivalent creep strain increases at the crack tip.

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