SPX Benchmark Part II: Transient Results

2021 ◽  
Author(s):  
Alexander Ponomarev ◽  
Konstantin Mikityuk ◽  
Emil Fridman ◽  
Vincenzo Anthony Di Nora ◽  
Evaldas Bubelis ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Power Distribution ◽  
Primary System ◽  
Monte Carlo Code ◽  
Kinetics Parameters ◽  
Sodium Fast Reactor ◽  
Start Up ◽  
Reactivity Coefficients ◽  
Point Kinetics

Abstract The paper presents a transient simulation phase of the new benchmark on a large sodium fast reactor (SFR). This phase of the benchmark is devoted to the modelling of selected operational transients performed during start-up tests of the French SFR Superphénix. Six operational transients were selected for the analysis. The specifications of a simplified thermal hydraulic model equipped with point kinetics reactivity data and boundary conditions for the selected transients are given in the paper. The developed model contains necessary thermal hydraulic description of the primary system components, assumptions to account for thermal expansion reactivity feedbacks from out-of-core structures, neutron kinetics parameters, power distribution, and reactivity coefficients. The neutronic input parameters were obtained with the help of the Monte Carlo code Serpent during the first phase of the benchmark related to static neutronic characterization of the core. In this study, the solution of the transient benchmark was obtained with three thermal hydraulic system codes, namely TRACE, SIM-SFR, and ATHLET. The numerical results, compared to the available experimental data, exhibit a reasonable mutual agreement. Particular discrepancies between calculations and experiments could not be fully resolved. Therefore, a set of recommendations for achieving an improved agreement was proposed. In general, the proposed transient benchmark can be seen as an effective tool for validation and cross comparisons of system codes applied for safety analyses of SFRs, including approbation and comparison of different modelling features for thermal expansion of the out-of-core structures.

Modeling of Reactivity Effects and Transient Behaviour of Large Sodium Fast Reactor

2021 ◽  
Author(s):  
Alexander Ponomarev ◽  
Konstantin Mikityuk
Keyword(s):  
Fast Reactor ◽  
Core Model ◽  
Primary System ◽  
Control Rod ◽  
Transient Behaviour ◽  
The Core ◽  
Sodium Fast Reactor ◽  
Reactivity Coefficients ◽  
Core Conditions ◽  
Point Kinetics

Abstract In the paper the reactivity characteristics of the core of the large sodium fast reactor Superphenix (SPX) were evaluated and compared with available experimental data. The analysis was performed using the TRACE system code modified for the fast reactor applications. The simplified core model was developed aiming to overcome the lack of detailed information on design and realistic core conditions. Point Kinetics neutronic model with all relevant reactivity feedbacks was used to calculate transient power. The paper focuses on challenging issue of modelling of the transient thermal responses of primary system structural elements resulting in reactivity feedbacks specific to such large fast reactor which cannot be neglected. For these effects, the model was equipped with dedicated heat structures to reproduce important feedbacks due to vessel wall, diagrid, strongback, control rod drive lines thermal expansion. Peculiarly, application of the model was considered for a whole range of core conditions from zero power to 100% nominal. The developed core model allowed reproducing satisfactorily the core reactivity balance between zero power at 180?C and full power conditions. Additionally, the reactivity coefficients k, g, h at three power levels were calculated and satisfactory agreement with experimental measurements was also observed. The study demonstrated feasibility of application of relatively simple model with adjusted parameters for analysis of different conditions of very complex system.

Calculation of effective point kinetics parameters in the Serpent 2 Monte Carlo code

2014 ◽  
Vol 65 ◽  
pp. 272-279 ◽  
Author(s):  
Jaakko Leppänen ◽  
Manuele Aufiero ◽  
Emil Fridman ◽  
Reuven Rachamin ◽  
Steven van der Marck
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Code ◽  
Kinetics Parameters ◽  
Point Kinetics

scholarly journals TOWARDS THE VALIDATION OF NOISE EXPERIMENTS IN THE CROCUS REACTOR USING THE TRIPOLI-4 MONTE CARLO CODE IN ANALOG MODE

2021 ◽  
Vol 247 ◽  
pp. 04007
Author(s):  
Oskari Pakari ◽  
Davide Mancusi ◽  
Odile Petit ◽  
Andrea Zoia ◽  
Vincent Lamirand ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Methods ◽  
Noise Analysis ◽  
Time Correlation ◽  
Monte Carlo Code ◽  
Spatial Effects ◽  
Kinetics Parameters ◽  
Neutron Noise ◽  
True Time ◽  
Point Kinetics

Intrinsic neutron noise experiments offer a non-invasive manner to measure the prompt decay constant or reactivity of fissile systems. Using the fluctuations in the density of fission chains, one can infer the kinetics parameters via correlation analysis such as the Rossi-alpha method. The models allowing for the interpretation of these measurements typically rely on the assumption of the system behaving according to point kinetics. When dealing with systems where point kinetics fail to predict the true time correlation – such as heterogeneous or large cores – the direct simulation of fission chains using Monte Carlo methods appears as the only reliable candidate to provide reference predictions for the correlation functions. Monte Carlo methods using explicit fission model libraries are thus being examined as tools for prediction in noise analysis. In this work we illustrate the developments and simulation results of the analog transport capabilities of the TRIPOLI-4 Monte Carlo code coupled with the LLNL fission library FREYA, as applied to a set of neutron noise experiments carried out in the CROCUS zero-power reactor with emphasis on the identification of spatial effects. To validate the general capability of the code to predict noise correlations, we examine time distributions of the whole core fission and explicit detection reactions. We present the methodology to achieve a good agreement between experiments and simulations. We reproduced experimental results for relative α, within typical biases, and conclude on the general feasibility of the analog method. We further explore a decoupled core model and analyze it using the noise method. The results indicate an effective method to treat decoupled systems.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

Dosimetric characterization of an 192Ir brachytherapy source with the Monte Carlo code PENELOPE

2010 ◽  
Vol 26 (3) ◽  
pp. 132-139 ◽  
Author(s):  
Francisco Javier Casado ◽  
Salvador García-Pareja ◽  
Elena Cenizo ◽  
Beatriz Mateo ◽  
Coral Bodineau ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Code ◽  
Brachytherapy Source

scholarly journals The effect of thermal expansion on diffusion flame instabilities

2010 ◽  
Vol 647 ◽  
pp. 453-472 ◽  
Author(s):  
M. MATALON ◽  
P. METZENER
Keyword(s):  
Thermal Expansion ◽  
Diffusion Flame ◽  
Initial Mixture ◽  
Surprising Result ◽  
Flame Instability ◽  
Preferential Diffusion ◽  
The Stability ◽  
Flame Instabilities ◽  
Comprehensive Characterization

In this paper we examine the effect of thermal expansion on the stability of a planar unstrained diffusion flame and provide a comprehensive characterization of diffusive-thermal instabilities while realistically accounting for density variations. The possible patterns that are likely to be observed as a result of differential and preferential diffusion are identified for a whole range of parameters including the distinct Lewis numbers associated with the fuel and oxidizer, the initial mixture strength and the flow conditions. Although we find that thermal expansion has a marked influence on flame instability, it does not play a crucial role as it does in premixed combustion. It primarily affects the parameter regime associated with the onset of the instabilities and the growth rate of the unstable modes. Perhaps the most surprising result is that its has a different influence on the various modes of instability – a destabilizing influence on the formation of cellular structures and a stabilizing influence on the onset of oscillations.

scholarly journals Characterization of materials for prosthetic implants using the BEAMnrc Monte Carlo code

2007 ◽  
Vol 74 ◽  
pp. 021016 ◽  
Author(s):  
E Spezi ◽  
F Palleri ◽  
A L Angelini ◽  
A Ferri ◽  
F Baruffaldi
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Code ◽  
Prosthetic Implants ◽  
Characterization Of Materials

Characterization of Phase Transitions Occurring in Solution Treated Ti-15Mo during Heating by Thermal Expansion and Electrical Resistance Measurements

2016 ◽  
Vol 879 ◽  
pp. 2318-2323 ◽  
Author(s):  
Pavel Zháňal ◽  
Petr Harcuba ◽  
Michal Hájek ◽  
Jana Šmilauerová ◽  
Jozef Veselý ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Titanium Alloy ◽  
Phase Transitions ◽  
Electrical Resistance ◽  
Temperature Changes ◽  
Solution Treated ◽  
Electrical Resistance Measurements ◽  
Ongoing Phase

Metastable β titanium alloy Ti-15Mo was investigated in this study. In-situ electrical resistance and thermal expansion measurements conducted on solution treated material revealed influence of ongoing phase transitions on measured properties. The monotonicity of the dependence of electrical resistance on temperature changes at 225, 365 and 560 °C The thermal expansion deviates from linearity between 305 and 580 °C.

Validating the Serpent-Ants Calculation Chain Using BEAVRS Fresh Core HZP Data

2021 ◽  
Author(s):  
Ville Valtavirta ◽  
Antti Rintala ◽  
Unna Lauranto
Keyword(s):  
Monte Carlo ◽  
Best Practices ◽  
Power Distribution ◽  
Measured Data ◽  
Monte Carlo Code ◽  
Generation Process ◽  
Isothermal Temperature ◽  
Control Rod ◽  
Temperature Coefficients ◽  
Group Constant

Abstract The Serpent Monte Carlo code and the Serpent-Ants two step calculation chain are used to model the hot zero power physics tests described in the BEAVRS benchmark. The predicted critical boron concentrations, control rod group worths and isothermal temperature coefficients are compared between Serpent and Serpent-Ants as well as against the experimental measurements. Furthermore, radial power distributions in the unrodded and rodded core configurations are compared between Serpent and Serpent-Ants. In addition to providing results using a best practices calculation chain, the effects of several simplifications or omissions in the group constant generation process on the results are estimated. Both the direct and two-step neutronics solutions provide results close to the measured values. Comparison between the measured data and the direct Serpent Monte Carlo solution yields RMS differences of 12.1 mg/kg, 25.1 × 10-5 and 0.67 × 10-5 K-1 for boron, control rod worths and temperature coefficients respectively. The two-step Serpent-Ants solution reaches a similar level of accuracy with RMS differences of 17.4 mg/kg, 23.6 × 10-5 and 0.29 × 10-5 K-1. The match in the radial power distribution between Serpent and Serpent-Ants was very good with the RMS and maximum for pin power errors being 1.31 % and 4.99 % respectively in the unrodded core and 1.67 %(RMS) and 8.39 % (MAX) in the rodded core.

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