Uncertainty Evaluation of the Rod Withdrawal at Power Accident Analysis Including 3D Neutron Kinetics

2012 ◽  
Author(s):  
Tomislav Bajs ◽  
Alessandro Petruzzi ◽  
Davor Grgić
Keyword(s):  
Temperature Measurement ◽  
Temperature Rise ◽  
Power Level ◽  
Three Dimensional ◽  
Nucleate Boiling ◽  
Coolant Temperature ◽  
System Response ◽  
Safety Margins ◽  
Control Assembly ◽  
System Variables

A continuous uncontrolled Rod Cluster Control Assembly (RCCA) bank withdrawal at power belongs to group of Reactivity Initiated Accidents (RIA). It will cause an increase in core heat flux and a reactor coolant temperature rise. Unless terminated by manual or automatic action, the power mismatch and resultant coolant temperature rise could eventually result in departure from nucleate boiling (DNB) and/or fuel centreline melt. The accident can be DNBR or overpower limiting accident depending on initial power level and rate and amount of reactivity addition. The Rod Withdrawal At Power (RWAP) accident was analyzed for NPP Krško to evaluate possible Resistance Temperature Detectors (RTD) bypass removal and introduction of thermowell for the average temperature measurement. The influence of different coolant temperature measurement delays to related protection system response and limiting system variables was studied first using point kinetics model as implemented in RELAP5 code. The selected scenario (maximum insertion rate with rods in manual mode) has been re-calculated using RELAP5/PARCS coupled code. Core wide departure from nucleate boiling ratio (DNBR) calculation has been performed at the end of the coupled code calculation using COBRA based model to determine minimum DNBR for hot channel. In order to assess available safety margins following such accident CIAU methodology has been applied to evaluate the uncertainty of RELAP5 analysis and modified CIAU/TN methodology to evaluate uncertainty of the three-dimensional neutronics/thermal-hydraulics calculations. Differences between system and coupled code results and uncertainties is discussed.

Inelastic Seismic Test of the Small Bore Piping and Support System: Part 1 — Seismic Proving Test of the Small Bore Piping System

2008 ◽  
Author(s):  
Eiji Shirai ◽  
Kazutoshi Eto ◽  
Akira Umemoto ◽  
Toshiaki Yoshii ◽  
Masami Kondo ◽  
...  
Keyword(s):  
Support System ◽  
Nuclear Power ◽  
Three Dimensional ◽  
System Response ◽  
Piping System ◽  
Inelastic Behavior ◽  
Seismic Safety ◽  
Plant Safety ◽  
Safety Margins ◽  
Support Element

Seismic safety is one of the major key issues of nuclear power plant safety in Japan. It is demonstrated that nuclear piping possesses large safety margins in the various piping ultimate test reports. But it is appeared that there still remain some technical uncertainties about the phenomenon when both piping and supports show inelastic behavior in the extremely high seismic excitation level. In order to obtain the influence of the inelastic behavior of the support to the whole piping system response, and the subsequent interaction when both piping and supports show inelastic behavior, the following two tests have been started. • Support element test: Load-displacement characteristics of the support system including U-bolt, support itself and concrete anchorage are obtained by the forced displacement test. • Seismic proving test of piping system: The small bore piping and support system consisted of three dimensional piping, supports, U-bolts, and concrete anchorages will be excited on the table by the extremely higher seismic level. This paper introduces the major results of seismic proving test of piping and support system. The support element test results is presented in the paper of part 2, and the simulation analyses of these tests are summarized in the paper of part 3 [1, 2].

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

scholarly journals Data-Informed Decomposition for Localized Uncertainty Quantification of Dynamical Systems

Vibration ◽  
2020 ◽  
Vol 4 (1) ◽  
pp. 49-63
Author(s):  
Waad Subber ◽  
Sayan Ghosh ◽  
Piyush Pandita ◽  
Yiming Zhang ◽  
Liping Wang
Keyword(s):  
Dynamical Systems ◽  
Computational Cost ◽  
Three Dimensional ◽  
Region Of Interest ◽  
System Response ◽  
Computational Domain ◽  
User Interest ◽  
Numerical Resolution ◽  
Multi Scale ◽  
Operation Conditions

Industrial dynamical systems often exhibit multi-scale responses due to material heterogeneity and complex operation conditions. The smallest length-scale of the systems dynamics controls the numerical resolution required to resolve the embedded physics. In practice however, high numerical resolution is only required in a confined region of the domain where fast dynamics or localized material variability is exhibited, whereas a coarser discretization can be sufficient in the rest majority of the domain. Partitioning the complex dynamical system into smaller easier-to-solve problems based on the localized dynamics and material variability can reduce the overall computational cost. The region of interest can be specified based on the localized features of the solution, user interest, and correlation length of the material properties. For problems where a region of interest is not evident, Bayesian inference can provide a feasible solution. In this work, we employ a Bayesian framework to update the prior knowledge of the localized region of interest using measurements of the system response. Once, the region of interest is identified, the localized uncertainty is propagate forward through the computational domain. We demonstrate our framework using numerical experiments on a three-dimensional elastodynamic problem.

Interface Temperature Measurement and Experimental Studies of Super-High Speed Polishing of CVD Diamond Films

2010 ◽  
Vol 135 ◽  
pp. 271-276
Author(s):  
Shu Tao Huang ◽  
Li Zhou ◽  
Li Fu Xu
Keyword(s):  
Stainless Steel ◽  
Temperature Measurement ◽  
Temperature Rise ◽  
Diamond Film ◽  
High Speed ◽  
Experimental Studies ◽  
Pure Titanium ◽  
Cvd Diamond ◽  
Interface Temperature ◽  
Cvd Diamond Film

Super-high speed polishing of diamond film is a newly proposed method due to its outstanding features such as low cost and simple apparatus. The interface temperature rise is due to the friction force and the relative sliding velocity between the CVD diamond film and the polishing metal plate surface. In this paper, the interface temperature rise in super-high speed polishing of CVD diamond film was investigated by using the single-point temperature measurement method. Additionally, the influence of polishing plate material on the characteristics of super-high speed polishing has been studied. The results showed that cast iron is not suitable for super-high polishing, while both 0Cr18Ni9 stainless steel and pure titanium can be used for the super-high polishing of CVD diamond film. The quality and efficiency of polishing with 0Cr18Ni9 stainless steel plate is much higher than those of pure titanium, and the material removal rate could reach to 36-51 m/h when the polishing speed and pressure are 100 m/s and 0.17-0.31 MPa, respectively.

scholarly journals A study about signal variation with minor receiver displacement in a meeting room at 60 GHz: measurements and simulations

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Muhammad Usman Sheikh ◽  
Kalle Ruttik ◽  
Riku Jäntti ◽  
Jyri Hämäläinen
Keyword(s):  
Power Level ◽  
Three Dimensional ◽  
60 Ghz ◽  
System Configuration ◽  
Conference Room ◽  
Channel Characteristics ◽  
Received Power ◽  
Simulation Results ◽  
Small Change ◽  
The Impact

AbstractThe aim of this work is to study the impact of small receiver displacement on a signal propagation in a typical conference room environment at a millimeter wave frequency of 60 GHz. While channel measurements provide insights on the propagation phenomena, their use for the wireless system performance evaluation is challenging. Whereas, carefully executed three-dimensional ray tracing (RT) simulations represent a more flexible option. Nevertheless, a careful validation of simulation methodology is needed. The first target of this article is to highlight the benefits of an in-house built three-dimensional RT tool at 60 GHz and shows the effectiveness of simulations in predicting different characteristics of the channel. To validate the simulation results against the measurements, two different transmitter (Tx) positions and antenna types along with ten receiver (Rx) positions are considered in a typical conference room. In first system configuration, an omnidirectional antenna is placed in the middle of the table, while in the second system configuration a directed horn antenna is located in the corner of the meeting room. After validating the simulation results with the measurement data, in the second part of this work, the impact of a small change, i.e., 20 cm in the receiver position, is studied. To characterize the impact, we apply as performance indicators the received power level, root mean square delay spread (RMS-DS) and RMS angular spread (RMS-AS) in azimuth plane. The channel characteristics are considered with respect to the direct orientation (DO), i.e., the Rx antenna is directed toward the strongest incoming path. Different antenna configurations at the Tx and Rx side are applied to highlight the role of antenna properties on the considered channel characteristics. Especially, in the second system configuration the impact of different antenna half power beamwidth on different considered channel characteristics is highlighted through acquired simulation results. The validation of results shows the RMS error of only 2–3 dB between the measured and simulated received power levels for different Tx configurations in the direction of DO. Results indicate that only a small change of the Rx position may result a large difference in the received power level even in the presence of line-of-sight between the Tx and Rx. It is found that the STD of received power level across the room increases with the decrease in HPBW of the antenna. As can be expected, directed antennas offer lower value of RMS-DS and RMS-AS compared with isotropic antenna.

Effect of Three-Dimensional Electric Field and Heat Conduction to Electrodes on the Temperature Rise During Irreversible Electroporation

2011 ◽  
Author(s):  
Seiji Nomura ◽  
Kosaku Kurata ◽  
Hiroshi Takamatsu
Keyword(s):  
Heat Conduction ◽  
Electric Field ◽  
Temperature Rise ◽  
Heat Conduction Equation ◽  
Thermal Damage ◽  
Irreversible Electroporation ◽  
Three Dimensional ◽  
End Effects ◽  
Abnormal Cells ◽  
Novel Method

The irreversible electroporation (IRE) is a novel method to ablate abnormal cells by applying a high voltage between two electrodes that are stuck into abnormal tissues. One of the advantages of the IRE is that the extracellular matrix (ECM) may be kept intact, which is favorable for healing. For a successful IRE, it is therefore important to avoid thermal damage of ECM resulted from the Joule heating within the tissue. A three-dimensional (3-D) analysis was conducted in this study to predict temperature rise during the IRE. The equation of electric field and the heat conduction equation were solved numerically by a finite element method. It was clarified that the highest temperature rise occurred at the base of electrodes adjacent to the insulated surface. The result was significantly different from a two-dimensional (2-D) analysis due to end effects, suggesting that the 3-D analysis is required to determine the optimal condition.

scholarly journals In-Situ Local Temperature Measurement During Three-Dimensional Direct Laser Writing

CLEO: 2013 ◽  
2013 ◽  
Author(s):  
Jonathan Mueller ◽  
Joachim Fischer ◽  
Yatin Jadavji Mange ◽  
Thomas Nann ◽  
Martin Wegener
Keyword(s):  
Temperature Measurement ◽  
Three Dimensional ◽  
Local Temperature ◽  
Direct Laser Writing ◽  
Laser Writing ◽  
Direct Laser

scholarly journals Computed Eccentricity Effects on Turbine Rim Seals at Engine Conditions With a Mainstream

1994 ◽  
Author(s):  
Zhou Guo ◽  
David L. Rhode ◽  
Fred M. Davis
Keyword(s):  
Reynolds Number ◽  
Temperature Rise ◽  
Three Dimensional ◽  
Computer Code ◽  
Interaction Effects ◽  
Navier Stokes ◽  
Radial Clearance ◽  
Turbine Wheel ◽  
Blade Root

A previously verified axisymmetric Navier-Stokes computer code was extended for three-dimensional computation of eccentric rim seals of almost any configuration. All compressibility and thermal/momentum interaction effects are completely, included, and the temperature, pressure and Reynolds number of the mainstream, coolant stream and turbine wheel are fixed at actual engine conditions. Regardless of the seal eccentricity, both ingress and egress are found between θ = −30° and 100°. which encompasses the location of maximum radial clearance at θ = 0°. All other θ locations within the rim seal show only egress, as does the concentric basecase for all circumferential locations. Further, the maximum ingress occurs near θ = 30° for all eccentricities. This is found to produce a blade root/retainer temperature rise from the concentric case of 390 percent at 50 percent eccentricity and a 77 percent rise at 7.5 percent eccentricity. In addition, the nature of an increased eccentricity causing a decreased seal effectiveness is examined, along with the corresponding increase of cavity-averaged temperature.

Thermal Effects Due to Surface Films in Sliding Contact

1994 ◽  
Vol 116 (2) ◽  
pp. 238-245 ◽  
Author(s):  
Brian Vick ◽  
L. P. Golan ◽  
M. J. Furey
Keyword(s):  
Thermal Properties ◽  
Temperature Rise ◽  
Thermal Effects ◽  
Three Dimensional ◽  
Sliding Contact ◽  
Frictional Heat ◽  
Solution Technique ◽  
Surface Films ◽  
Thermal Coupling ◽  
Efficient Manner

The present work examines theoretically the influence of surface coatings on the temperatures produced by friction due to sliding contact. A generalized thermal model is developed which incorporates three-dimensional, transient heat transfer between layered media with thermal coupling at multiple, interacting contact patches. A solution technique based on a variation of the boundary element method is developed and utilized. The method allows for the solution of the distribution of frictional heat and the resulting temperature rise in an accurate yet numerically efficient manner. Results are presented showing the influence of film thickness, thermal properties, velocity, and contact area on the division of heat and surface temperature rise. The results show that a film with thermal properties different than those of the substrate can have a pronounced effect on the predicted temperature rise.

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