scholarly journals Sensitivity Analysis of the TRIGA IPR-R1 Reactor Models Using the MCNP Code

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
C. A. M. Silva ◽  
J. A. D. Salomé ◽  
B. T. Guerra ◽  
C. Pereira ◽  
A. L. Costa ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Sensitivity Analyses ◽  
Different Types ◽  
Effective Multiplication Factor ◽  
Neutronic Parameters ◽  
Input Variables ◽  
Reactor Models ◽  
Different Levels ◽  
Effective Multiplication ◽  
Good Agreement

In the process of verification and validation of code modelling, the sensitivity analysis including systematic variations in code input variables must be used to help identifying the relevant parameters necessary for a determined type of analysis. The aim of this work is to identify how much the code results are affected by two different types of the TRIGA IPR-R1 reactor modelling processes performed using the MCNP (Monte Carlo N-Particle Transport) code. The sensitivity analyses included small differences of the core and the rods dimensions and different levels of model detailing. Four models were simulated and neutronic parameters such as effective multiplication factor (keff), reactivity (ρ), and thermal and total neutron flux in central thimble in some different conditions of the reactor operation were analysed. The simulated models presented good agreement between them, as well as in comparison with available experimental data. In this way, the sensitivity analyses demonstrated that simulations of the TRIGA IPR-R1 reactor can be performed using any one of the four investigated MCNP models to obtain the referenced neutronic parameters.

Representative neutronic characteristics calculations for the VVER-1000 reactors using SRAC and MCNP5

2016 ◽  
Vol 6 (2) ◽  
pp. 21-30
Author(s):  
Huu Tiep Nguyen ◽  
Viet Phu Tran ◽  
Tuan Khai Nguyen ◽  
Vinh Thanh Tran ◽  
Minh Tuan Nguyen
Keyword(s):  
Monte Carlo ◽  
Power Distribution ◽  
Reactor Core ◽  
Multiplication Factor ◽  
Benchmark Problem ◽  
Fuel Assemblies ◽  
Effective Multiplication Factor ◽  
Neutronic Characteristics ◽  
Effective Multiplication ◽  
Good Agreement

This paper presents the results of neutronic calculations using the deterministic and Monte-Carlo methods (the SRAC and MCNP5codes) for the VVER MOX Core Computational Benchmark Specification and the VVER-1000/V392 reactor core. The power distribution and keff value have been calculated for a benchmark problem of VVER core. The results show a good agreement between the SRAC and MCNP5 calculations. Then, neutronic characteristics of VVER-1000/V392 such as power distribution, infinite multiplication factor (k-inf) of the fuel assemblies, effective multiplication factor keff, peaking factor and Doppler coefficient were calculated using the two codes.

scholarly journals Global Sensitivity Analysis of Ultimate Limit States of Stainless Steel Structural Members

2021 ◽  
Vol 1203 (2) ◽  
pp. 022142
Author(s):  
Abayomi Omishore
Keyword(s):  
Sensitivity Analysis ◽  
Stainless Steel ◽  
Yield Strength ◽  
Higher Order ◽  
Carbon Steels ◽  
Sensitivity Analyses ◽  
Statistical Characteristics ◽  
Limit States ◽  
Sensitivity Indices ◽  
Input Variables

Abstract The article presents global Sobol sensitivity analysis of a rolled member in tension made from austenitic chromium-nickel stainless steel of type 1.4307/AISI 304 L. The statistical characteristics of yield strength and of the geometry of the rolled steel IPE cross-section are presented on the basis of published experimental research. The sensitivity analysis showed the dominant effect of the yield strength on the static resistance. The second dominant variable is the flange thickness. Higher-order sensitivity indices oriented at detecting the presence of interaction effects between input variables are very small. The characteristics of other types of sensitivity analyses oriented at quantiles or the probability of failure are discussed, especially in terms of a higher proportion of higher-order sensitivity indices. The results of Sobol sensitivity analysis of stainless steel are compared with similar results of carbon steels.

How Tree Risk Assessment Methods Work: Sensitivity Analyses of Sixteen Methods Reveal the Value of Quantification and the Impact of Inputs on Risk Ratings

2020 ◽  
Vol 46 (6) ◽  
pp. 402-431
Author(s):  
M.B. Norris ◽  
G.M. Moore
Keyword(s):  
Risk Assessment ◽  
Sensitivity Analysis ◽  
Latin Hypercube Sampling ◽  
Assessment Methods ◽  
Sensitivity Analyses ◽  
Risk Level ◽  
Input Variables ◽  
Group 2 ◽  
The Impact ◽  
Risk Scale

Sixteen tree risk assessment methods were subjected to sensitivity analysis to determine which factors most influenced the output of each method. The analyses indicate the relative influence that the input variables exert on the final risk value. Excel was used to create a simple ± 25% or ± 1 rank change (depending on the method) for each criterion, with the change to the output recorded as a percentage. Palisade’s @Risk software was used to undertake a Monte Carlo (with Latin Hypercube sampling) simulation of 5000 iterations based on the input variables and output formula. From the simulation, multivariate stepwise regression was undertaken to determine the influence of each method’s input variables in determining the output values. Results from the sensitivity analysis indicate some clear and strong differences amongst the 16 methods, reflecting that the underlying mathematics, input categories, ranges, and scaling influence the way that different methods process and express risk. It is not surprising that methods perform differently in different circumstances and express risk level differently. The analyses demonstrated that most methods placed too great an emphasis on limited aspects of risk assessment. Most methods strongly focused on the hazard or defect aspects of assessment and the likelihood of failure rather than the consequence aspect of an assessment. While methods were uniquely different, they could be placed into 3 broad groups: Group 1 methods produced a normal distribution with most values around the mean; Group 2 methods produced outputs at the lower end of the risk scale; and Group 3 methods produced outputs evenly if not continuously across the risk scale. Users of tree risk assessment should understand the strengths and weaknesses of any method used, as it could be relatively simple to challenge the results of a risk assessment based on limitations inherent in the underlying methodology.

scholarly journals Effect of MOX fuel and the ENDF/B-VIII on the AP1000 neutronic parameters calculations by using MCNP6

2019 ◽  
Vol 34 (4) ◽  
pp. 325-335
Author(s):  
Sonia Reda ◽  
Ibrahim Gomaa ◽  
Ibrahim Bashter ◽  
Esmat Amin
Keyword(s):  
Reactor Core ◽  
Delayed Neutron ◽  
Optimization Criteria ◽  
Mox Fuel ◽  
235U Enrichment ◽  
Reactivity Coefficients ◽  
Effective Multiplication Factor ◽  
Neutronic Parameters ◽  
Ap1000 Reactor ◽  
Effective Multiplication

The present work studies the effect of introducing MOX fuel on Westinghouse AP1000 neutronic parameters. The neutronic calculations were performed by using the MCNP6 code with the ENDF/B-VII.1 library and the new release of the ENDF/B-VIII, the AP1000 core with three 235U enrichment zones (2.35 %, 3.40 %, and 4.45 %). The obtained results showed that the simulated model for the AP1000 core satisfies the optimization criteria as a Westing- house reference. The results which included: effective multiplication factor, keff, delayed neutron fraction, beff, excess reactivity, rex, shutdown margin, temperature reactivity coefficients, whole core depletion, neutron flux, power peaking factor and core power density, were calculated and compared with the available published results. The keff in the cold zero power was found to be 1.20495 and 1.20247 with the ENDF/B-VII.1 and the ENDF/B-VIII libraries, respectively, which matches the value of 1.205 presented in the AP1000 Design Control Document for the UO2 fuel core. On the other hand, keff in the cold zero power was found to be 1.19988 and 1.19860 for MOX core with the ENDF/B-VII.1 and the ENDF/B-VIII libraries, respectively, which show good reception and confirm the safety of the design and efficient modeling of AP1000 reactor core.

Pipe Response Under Concentrated Lateral Loads and External Pressure

2006 ◽  
Author(s):  
Kyros P. Andreadakis ◽  
Spyros A. Karamanos
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Three Dimensional ◽  
External Pressure ◽  
Pressure Effects ◽  
Lateral Loads ◽  
End Conditions ◽  
Different Types ◽  
Different Levels ◽  
Good Agreement

The paper focuses on the denting the response of pipeline segments subjected to lateral quasi-static wedge loading, in the presence of internal pressure. Nonlinear finite element models of pipeline segments, which are in good agreement with denting test data from internally pressurized pipes, are employed to obtain load-deflection curves for different levels of pressure, for various wedge shapes and for different types of boundary conditions. It is found that the presence of internal pressure increases significantly the denting resistance. The present study gives special emphasis on the development of a simplified three-dimensional analytical model, which yields closed-form expressions for the denting force and the corresponding denting length in terms of the corresponding denting displacement. The model, introduced elsewhere for non-pressurized tubes, is enhanced to include the pressure effects, accounting for different types of pipe end conditions. The analytical solution compares very well with the finite element results, and illustrates tube denting response in a clear and elegant manner.

A Primer on the Assessment of Economic Impacts of Leisure Events

2020 ◽  
Vol 24 (1) ◽  
pp. 47-56
Author(s):  
Ove Oklevik ◽  
Grzegorz Kwiatkowski ◽  
Mona Kristin Nytun ◽  
Helene Maristuen
Keyword(s):  
Impact Assessment ◽  
Economic Impact ◽  
Study Design ◽  
Impact Analysis ◽  
Sensitivity Analyses ◽  
Primary Data ◽  
Music Festival ◽  
Economic Impact Analysis ◽  
Economic Impact Assessment ◽  
Input Variables

The quality of any economic impact assessment largely depends on the adequacy of the input variables and chosen assumptions. This article presents a direct economic impact assessment of a music festival hosted in Norway and sensitivity analyses of two study design assumptions: estimated number of attendees and chosen definition (size) of the affected area. Empirically, the article draws on a state-of-the-art framework of an economic impact analysis and uses primary data from 471 event attendees. The results show that, first, an economic impact analysis is a complex task that requires high precision in assessing different monetary flows entering and leaving the host region, and second, the study design assumptions exert a tremendous influence on the final estimation. Accordingly, the study offers a fertile agenda for local destination marketing organizers and event managers on how to conduct reliable economic impact assessments and explains which elements of such analyses are particularly important for final estimations.

A model to account for the consequences of host nutrition on the outcome of gastrointestinal parasitism in sheep: model evaluation

Parasitology ◽  
2007 ◽  
Vol 134 (9) ◽  
pp. 1279-1289 ◽  
Author(s):  
D. VAGENAS ◽  
S. C. BISHOP ◽  
I. KYRIAZAKIS
Keyword(s):  
Mathematical Model ◽  
Worm Burden ◽  
Management Strategies ◽  
Sensitivity Analyses ◽  
Sheep Model ◽  
Host Nutrition ◽  
Gastrointestinal Parasitism ◽  
Different Characteristics ◽  
Nutritional Strategies ◽  
Different Levels

SUMMARYThis paper describes sensitivity analyses and expectations obtained from a mathematical model developed to account for the effects of host nutrition on the consequences of gastrointestinal parasitism in sheep. The scenarios explored included different levels of parasitic challenge at different planes of nutrition, for hosts differing only in their characteristics for growth. The model was able to predict the consequences of host nutrition on the outcome of parasitism, in terms of worm burden, number of eggs excreted per gram faeces and animal performance. The model outputs predict that conclusions on the ability of hosts of different characteristics for growth to cope with parasitism (i.e. resistance) depend on the plane of nutrition. Furthermore, differences in the growth rate of sheep, on their own, are not sufficient to account for differences in the observed resistance of animals. The model forms the basis for evaluating the consequences of differing management strategies and environments, such as breeding for certain traits associated with resistance and nutritional strategies, on the consequences of gastrointestinal parasitism on sheep.

scholarly journals IMMU-04. IMMUNE-RELATED ADVERSE EVENTS STRONGLY PREDICT SUPERIOR OUTCOMES IN BRAIN METASTASES PATIENTS RECEIVING LOCAL TREATMENT AND IMMUNE CHECKPOINT INHIBITORS

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii105-ii105
Author(s):  
Alexander Hulsbergen ◽  
Asad Lak ◽  
Yu Tung Lo ◽  
Nayan Lamba ◽  
Steven Nagtegaal ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Adverse Events ◽  
Brain Metastases ◽  
Immune Checkpoint ◽  
Immune Checkpoint Inhibitors ◽  
Checkpoint Inhibitors ◽  
Local Treatment ◽  
Sensitivity Analyses ◽  
Immortal Time Bias ◽  
The Brain

Abstract INTRODUCTION In several cancers treated with immune checkpoint inhibitors (ICIs), a remarkable association between the occurrence of immune-related adverse events (irAEs) and superior oncological outcomes has been reported. This effect has hitherto not been reported in the brain. This study aimed to investigate the relation between irAEs and outcomes in brain metastases (BM) patients treated with both local treatment to the brain (LT; i.e. surgery and/or radiation) and ICIs. METHODS This study is a retrospective cohort analysis of patients treated for non-small cell lung cancer (NSCLC) BMs in a tertiary institution in Boston, MA. Outcomes of interest were overall survival (OS) and intracranial progression-free survival (IC-PFS), measured from the time of LT. Sensitivity analyses were performed to account for immortal time bias (i.e., patients who live longer receive more cycles of ICIs and thus have more opportunity to develop an irAE). RESULTS A total of 184 patients were included; 62 (33.7%) were treated with neurosurgical resection and 122 (66.3%) with upfront brain radiation. irAEs occurred in 62 patients (33.7%). After adjusting for lung-Graded Prognostic Assessment, type of LT, type of ICI, newly diagnosed vs. recurrent BM, BM size and number, targetable mutations, and smoking status, irAEs were strongly associated with better OS (HR 0.33, 95% CI 0.19 – 0.58, p < 0.0001) and IC-PFS (HR 0.41; 95% CI 0.26 – 0.65; p = 0.0001). Landmark analysis including only patients who received more than 3 cycles of ICI (n = 133) demonstrated similar results for OS and IC-PFS, as did sensitivity analysis adjusting for the number of cycles administered (HR range 0.36 – 0.51, all p-values < 0.02). CONCLUSIONS After adjusting for known prognostic factors, irAEs strongly predict superior outcomes after LT in NSCLC BM patients. Sensitivity analysis suggests that this is unlikely due to immortal time bias.

scholarly journals Constitutive Modeling of the Densification Behavior in Open-Porous Cellular Solids

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2731
Author(s):  
Ameya Rege
Keyword(s):  
Constitutive Model ◽  
Cell Walls ◽  
Compressive Strain ◽  
Pore Collapse ◽  
Compressive Response ◽  
Linear Elastic ◽  
Nonlinear Springs ◽  
Different Types ◽  
Point Of Intersection ◽  
Good Agreement

The macroscopic mechanical behavior of open-porous cellular materials is dictated by the geometric and material properties of their microscopic cell walls. The overall compressive response of such materials is divided into three regimes, namely, the linear elastic, plateau and densification. In this paper, a constitutive model is presented, which captures not only the linear elastic regime and the subsequent pore-collapse, but is also shown to be capable of capturing the hardening upon the densification of the network. Here, the network is considered to be made up of idealized square-shaped cells, whose cell walls undergo bending and buckling under compression. Depending on the choice of damage criterion, viz. elastic buckling or irreversible bending, the cell walls collapse. These collapsed cells are then assumed to behave as nonlinear springs, acting as a foundation to the elastic network of active open cells. To this end, the network is decomposed into an active network and a collapsed one. The compressive strain at the onset of densification is then shown to be quantified by the point of intersection of the two network stress-strain curves. A parameter sensitivity analysis is presented to demonstrate the range of different material characteristics that the model is capable of capturing. The proposed constitutive model is further validated against two different types of nanoporous materials and shows good agreement.

scholarly journals A Novel Global Sensitivity Measure Based on Probability Weighted Moments

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 90
Author(s):  
Shufang Song ◽  
Lu Wang
Keyword(s):  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Small Samples ◽  
Double Loop ◽  
Numerical Estimation ◽  
Global Sensitivity ◽  
Sensitivity Measure ◽  
Probability Weighted Moments ◽  
Input Variables ◽  
Single Set

Global sensitivity analysis (GSA) is a useful tool to evaluate the influence of input variables in the whole distribution range. Variance-based methods and moment-independent methods are widely studied and popular GSA techniques despite their several shortcomings. Since probability weighted moments (PWMs) include more information than classical moments and can be accurately estimated from small samples, a novel global sensitivity measure based on PWMs is proposed. Then, two methods are introduced to estimate the proposed measure, i.e., double-loop-repeated-set numerical estimation and double-loop-single-set numerical estimation. Several numerical and engineering examples are used to show its advantages.

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