Sensitivity Analysis of 200 mm LOCA at Armenian NPP Unit 2

2004 ◽  
Author(s):  
Armen Amirjanyan ◽  
Tsolak Malakyan ◽  
Jae Jo
Keyword(s):  
Sensitivity Analysis ◽  
Safety Margin ◽  
Sensitivity Analyses ◽  
Equivalent Diameter ◽  
Diesel Generator ◽  
Acceptance Criteria ◽  
Safety Margins ◽  
Station Blackout ◽  
Diesel Generators ◽  
Safety Limit

This paper presents the results of sensitivity analyses of a loss-of-coolant accident (LOCA) with equivalent diameter of 200 mm on a cold leg at Armenian Nuclear Power Plant (ANPP) Unit 2. ANPP is a six-loop WWER-440/270 model of Russian design. Analyses performed for the Technical Assignment for WWER-440/270 reactors showed that this reactor had high safety margins with 100 mm LOCA, which may allow increasing the safety level for the maximum design base LOCA. To demonstrate the adequacy of the safety margin with equivalent diameter of 200 mm using the existing high-pressure injection (HPI) system, analyses of LOCAs with break sizes of the equivalent diameter of 200mm in the primary side were previously performed with highly conservative assumptions using the RELAP5 code (Mod3.2.2β). Results of this study were reported at ICONE 11. The results of LOCA analyses with highly conservative assumptions showed that the acceptance criteria were not exceeded in the cases of a surge line break and equivalent break on a hot leg. However, calculations for a break with equivalent diameter of 200 mm on a cold leg showed that the cladding temperature reached 1235 °C, narrowly exceeding the safety limit mentioned in acceptance criteria (1204 °C), and prompted to conduct additional sensitivity studies with slightly relaxed conservative assumptions. At ANPP, there are two trains of HPI systems with two diesel generators on each train and one additional generator in the reserve state. Each train of diesel generators supplies power to two HPI pumps. However, in the current ANPP configuration, only one HPI pump in each train is automatically switched on to diesel generators in case of a station blackout. Therefore, the previous analysis of LOCA with highly conservative assumptions took credit for only two HPI pumps available after station blackout (i.e., two of diesel generators and reserve diesel generator are not available). The current ANPP modernization plan includes automatic starts of four HPI pumps. For this sensitivity analysis we took credit for one additional HPI pump (namely, three HPI pumps all together). As in the previous calculations, a loss of off-site power was assumed at the moment of accident beginning and simultaneous reactor scram: diesel generators were assumed to be available 20 seconds after the off-site power loss. The results of this sensitivity calculation of LOCA with equivalent diameter of 200 mm on a cold leg show that the cladding temperature stayed far below the safety limit. The peak cladding temperature was 850°C, well below that of the original study (1235°C) and the safety limit in the acceptance criteria (1204°C).

scholarly journals Bootstrap and Order Statistics for Quantifying Thermal-Hydraulic Code Uncertainties in the Estimation of Safety Margins

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Enrico Zio ◽  
Francesco Di Maio
Keyword(s):  
Confidence Interval ◽  
Order Statistics ◽  
Nuclear Reactor ◽  
Safety Margin ◽  
Fuel Cladding ◽  
Complete Group ◽  
Bootstrap Technique ◽  
Safety Margins ◽  
Group Distribution

In the present work, the uncertainties affecting the safety margins estimated from thermal-hydraulic code calculations are captured quantitatively by resorting to the order statistics and the bootstrap technique. The proposed framework of analysis is applied to the estimation of the safety margin, with its confidence interval, of the maximum fuel cladding temperature reached during a complete group distribution blockage scenario in a RBMK-1500 nuclear reactor.

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.

Optimal tuned direct adaptive controller for seismic protecting of structures

2021 ◽  
pp. 1045389X2098878
Author(s):  
Amin Hosseini ◽  
Touraj Taghikhany ◽  
Milad Jahangiri
Keyword(s):  
Sensitivity Analysis ◽  
Adaptive Control ◽  
Optimization Problem ◽  
Adaptive Controller ◽  
Sensitivity Analyses ◽  
Building Structures ◽  
Building Structure ◽  
The Past ◽  
Innovative Method ◽  
Story Building

In the past few years, many studies have proved the efficiency of Simple Adaptive Control (SAC) in mitigating earthquakes’ damages to building structures. Nevertheless, the weighting matrices of this controller should be selected after a large number of sensitivity analyses. This step is time-consuming and it will not necessarily yield a controller with optimum performance. In the current study, an innovative method is introduced to tuning the SAC’s weighting matrices, which dispenses with excessive sensitivity analysis. In this regard, we try to define an optimization problem using intelligent evolutionary algorithm and utilized control indices in an objective function. The efficiency of the introduced method is investigated in 6-story building structure equipped with magnetorheological dampers under different seismic actions with and without uncertainty in the model of the proposed structure. The results indicate that the controller designed by the introduced method has a desirable performance under different conditions of uncertainty in the model. Furthermore, it improves the seismic performance of structure as compared to controllers designed through sensitivity analysis.

scholarly journals Sensitivity analysis of a coupled hydrodynamic-vegetation model using the effectively subsampled quadratures method (ESQM v5.2)

2017 ◽  
Vol 10 (12) ◽  
pp. 4511-4523 ◽  
Author(s):  
Tarandeep S. Kalra ◽  
Alfredo Aretxabaleta ◽  
Pranay Seshadri ◽  
Neil K. Ganju ◽  
Alexis Beudin
Keyword(s):  
Sensitivity Analysis ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Aquatic Vegetation ◽  
Three Dimensional ◽  
Sensitivity Analyses ◽  
Stem Density ◽  
Sobol Indices ◽  
Plant Stem ◽  
Wave Induced

Abstract. Coastal hydrodynamics can be greatly affected by the presence of submerged aquatic vegetation. The effect of vegetation has been incorporated into the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system. The vegetation implementation includes the plant-induced three-dimensional drag, in-canopy wave-induced streaming, and the production of turbulent kinetic energy by the presence of vegetation. In this study, we evaluate the sensitivity of the flow and wave dynamics to vegetation parameters using Sobol' indices and a least squares polynomial approach referred to as the Effective Quadratures method. This method reduces the number of simulations needed for evaluating Sobol' indices and provides a robust, practical, and efficient approach for the parameter sensitivity analysis. The evaluation of Sobol' indices shows that kinetic energy, turbulent kinetic energy, and water level changes are affected by plant stem density, height, and, to a lesser degree, diameter. Wave dissipation is mostly dependent on the variation in plant stem density. Performing sensitivity analyses for the vegetation module in COAWST provides guidance to optimize efforts and reduce exploration of parameter space for future observational and modeling work.

COST-EFFECTIVENESS ANALYSIS OF IVABRADINE IN TREATMENT OF PATIENTS WITH HEART FAILURE IN IRAN

2018 ◽  
Vol 34 (6) ◽  
pp. 576-583 ◽  
Author(s):  
Saeed Taheri ◽  
Elham Heidari ◽  
Mohammad Ali Aivazi ◽  
Mehran Shams-Beyranvand ◽  
Mehdi Varmaghani
Keyword(s):  
Heart Failure ◽  
Sensitivity Analysis ◽  
Cost Effectiveness ◽  
Incremental Cost ◽  
Transition Probabilities ◽  
Drug Acquisition ◽  
Sensitivity Analyses ◽  
Baseline Heart Rate ◽  
Life Years ◽  
The Cost

Objectives:This study aimed to assess the cost-effectiveness of ivabradine plus standard of care (SoC) in comparison with current SoC alone from the Iranian payer perspective.Methods:A cohort-based Markov model was developed to assess the incremental cost-effectiveness ratio (ICER) over a 10-year time horizon in a cohort of 1,000 patients. The baseline transition probabilities between New York Heart Association (NYHA), mortality rate, and hospitalization rate were extracted from the literature. The effect of ivabradine on mortality, hospitalization, and NYHA improvement or worsening were retrieved from the SHIFT study. The effectiveness was measured as quality-adjusted life-years (QALYs) using the utility values derived from Iranian Heart Failure Quality of Life study. Direct medical costs were obtained from hospital records and national tariffs. Deterministic and probabilistic sensitivity analyses were conducted to show the robustness of the model.Results:Ivabradine therapy was associated with an incremental cost per QALY of USD $5,437 (incremental cost of USD $2,207 and QALYs gained 0.41) versus SoC. The probabilistic sensitivity analysis showed that ivabradine is expected to have a 60 percent chance of being cost-effective accepting a threshold of USD $6,550 per QALY. Furthermore, deterministic sensitivity analysis indicated that the model is sensitive to the ivabradine drug acquisition cost.Conclusions:The cost-effectiveness model suggested that the addition of ivabradine to SoC therapy was associated with improved clinical outcomes along with increased costs. The analysis indicates that the clinical benefit of ivabradine can be achieved at a reasonable cost in eligible heart failure patients with sinus rhythm and a baseline heart rate ≥ 75 beats per minute (bpm).

scholarly journals Adjoint-based parametric sensitivity analysis for swirling M-flames

2018 ◽  
Vol 859 ◽  
pp. 516-542 ◽  
Author(s):  
Calum S. Skene ◽  
Peter J. Schmid
Keyword(s):  
Sensitivity Analysis ◽  
Frequency Response ◽  
Stokes Equations ◽  
Numerical Study ◽  
Computational Cost ◽  
Base Flow ◽  
Sensitivity Analyses ◽  
Perturbation Expansions ◽  
Mean Flow ◽  
Adjoint Solutions

A linear numerical study is conducted to quantify the effect of swirl on the response behaviour of premixed lean flames to general harmonic excitation in the inlet, upstream of combustion. This study considers axisymmetric M-flames and is based on the linearised compressible Navier–Stokes equations augmented by a simple one-step irreversible chemical reaction. Optimal frequency response gains for both axisymmetric and non-axisymmetric perturbations are computed via a direct–adjoint methodology and singular value decompositions. The high-dimensional parameter space, containing perturbation and base-flow parameters, is explored by taking advantage of generic sensitivity information gained from the adjoint solutions. This information is then tailored to specific parametric sensitivities by first-order perturbation expansions of the singular triplets about the respective parameters. Valuable flow information, at a negligible computational cost, is gained by simple weighted scalar products between direct and adjoint solutions. We find that for non-swirling flows, a mode with azimuthal wavenumber $m=2$ is the most efficiently driven structure. The structural mechanism underlying the optimal gains is shown to be the Orr mechanism for $m=0$ and a blend of Orr and other mechanisms, such as lift-up, for other azimuthal wavenumbers. Further to this, velocity and pressure perturbations are shown to make up the optimal input and output showing that the thermoacoustic mechanism is crucial in large energy amplifications. For $m=0$ these velocity perturbations are mainly longitudinal, but for higher wavenumbers azimuthal velocity fluctuations become prominent, especially in the non-swirling case. Sensitivity analyses are carried out with respect to the Mach number, Reynolds number and swirl number, and the accuracy of parametric gradients of the frequency response curve is assessed. The sensitivity analysis reveals that increases in Reynolds and Mach numbers yield higher gains, through a decrease in temperature diffusion. A rise in mean-flow swirl is shown to diminish the gain, with increased damping for higher azimuthal wavenumbers. This leads to a reordering of the most effectively amplified mode, with the axisymmetric ($m=0$) mode becoming the dominant structure at moderate swirl numbers.

scholarly journals Cost of coils for intracranial aneurysms: clinical decision analysis for implementation of a capitation model

2018 ◽  
Vol 128 (6) ◽  
pp. 1792-1798 ◽  
Author(s):  
Gurpreet S. Gandhoke ◽  
Yash K. Pandya ◽  
Ashutosh P. Jadhav ◽  
Tudor Jovin ◽  
Robert M. Friedlander ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Probabilistic Sensitivity Analysis ◽  
Cost Savings ◽  
Clinical Decision ◽  
Sensitivity Analyses ◽  
List Price ◽  
Maximum Dimension ◽  
Total Length ◽  
The Mean ◽  
Mean Cost

OBJECTIVEThe price of coils used for intracranial aneurysm embolization has continued to rise despite an increase in competition in the marketplace. Coils on the US market range in list price from $500 to $3000. The purpose of this study was to investigate potential cost savings with the use of a price capitation model.METHODSThe authors built a clinical decision analytical tree and compared their institution’s current expenditure on endovascular coils to the costs if a capped-price model were implemented. They retrospectively reviewed coil and cost data for 148 patients who underwent coil embolization from January 2015 through September 2016. Data on the length and number of coils used in all patients were collected and analyzed. The probabilities of a treated aneurysm being ≤/> 10 mm in maximum dimension, the total number of coils used for a case being ≤/> 5, and the total length of coils used for a case being ≤/> 50 cm were calculated, as was the mean cost of the currently used coils for all possible combinations of events with these probabilities. Using the same probabilities, the authors calculated the expected value of the capped-price strategy in comparison with the current one. They also conducted multiple 1-way sensitivity analyses by applying plausible ranges to the probabilities and cost variables. The robustness of the results was confirmed by applying individual distributions to all studied variables and conducting probabilistic sensitivity analysis.RESULTSNinety-five (64%) of 148 patients presented with a rupture, and 53 (36%) were treated on an elective basis. The mean aneurysm size was 6.7 mm. A total of 1061 coils were used from a total of 4 different providers. Companies A (72%) and B (16%) accounted for the major share of coil consumption. The mean number of coils per case was 7.3. The mean cost per case (for all coils) was $10,434. The median total length of coils used, for all coils, was 42 cm. The calculated probability of treating an aneurysm less than 10 mm in maximum dimension was 0.83, for using 5 coils or fewer per case it was 0.42, and for coil length of 50 cm or less it was 0.89. The expected cost per case with the capped policy was calculated to be $4000, a cost savings of $6564 in comparison with using the price of Company A. Multiple 1-way sensitivity analyses revealed that the capped policy was cost saving if its cost was less than $10,500. In probabilistic sensitivity analyses, the lowest cost difference between current and capped policies was $2750.CONCLUSIONSIn comparison with the cost of coils from the authors’ current provider, their decision model and probabilistic sensitivity analysis predicted a minimum $407,000 to a maximum $1,799,976 cost savings in 148 cases by adapting the capped-price policy for coils.

scholarly journals Measuring the sensitivity of difference-in-difference estimates to the parallel trends assumption

2021 ◽  
pp. 263208432110613
Author(s):  
Landon Gibson ◽  
Frederick Zimmerman
Keyword(s):  
Sensitivity Analysis ◽  
Treatment Period ◽  
Treatment Effect ◽  
Statistical Tests ◽  
Sensitivity Analyses ◽  
Difference In Difference ◽  
Control Groups ◽  
Pre Treatment ◽  
Background Difference ◽  
And Control

Background. Difference-in-Difference makes a critical assumption that the changes in the outcomes, over the post-treatment period, are similar between the treated and control groups—the parallel trends assumption. Evaluation of this assumption is often done either by graphical examination or by statistical tests in the pre-treatment period. They result in a binary conclusion about the validity of the assumption. Purpose. This paper proposes a sensitivity analysis that quantifies the departure from parallel trends necessary to meaningfully change the estimated treatment effect. Results. Sensitivity analyses have an advantage over traditional parallel trends tests: they use all available data and thereby work even if only one pre-period is available, and they quantify the strength of unobserved confounder(s) required to change the conclusions of a study. Conclusions. We apply the sensitivity analysis metrics developed by Cinelli and Hazlett (2020) and illustrate them on two studies.

scholarly journals Stand Alone 1-MW Microgrid for Remote locations of Armed Forces with PV-Battery-Diesel Generator

2020 ◽  
Vol 10 (1) ◽  
pp. 350-358
Keyword(s):  
Renewable Energy ◽  
Solar Power ◽  
Storage System ◽  
Armed Forces ◽  
Diesel Generator ◽  
Pv System ◽  
Night Time ◽  
Power Requirement ◽  
Remote Areas ◽  
Diesel Generators

Many times, Armed Forces are deployed in bases in remote areas on the borders or Islands, which are far flung areas away from mainland. In many such cases, these areas do not have their power requirements through the main grid supply and entire power requirement of the deployment is supplied by diesel generators. These diesel generators have high environmental impact due to emission of greenhouse gases and are highly uneconomical as logistic sustenance of remote bases for supply of fuel is very challenging, Fossil fuel has to be supplied by vehicles, helicopters, boats or manually carried to hill tops. This increases the overall cost of deploying armed forces in remote areas. In recent years with the advancements in power electronic components and renewable energy, development in Microgrids (MGs) have shown a way to reduce dependency on main power grids. Hence, with the help of MGs, renewable energy can be used to fulfill power requirements of the armed forces deployed in remote places. In this work, a MG with capacity of 1MW has been designed keeping the special needs of armed forces as a major consideration. Solar power has been used as a primary renewable energy source in the proposed design. In order to mitigate the adverse effects of meteorological and extreme conditions on the solar power generation capacity, energy storage system in the form of batteries has also been provided. Batteries store power when excess power is generated from the photo voltaic (PV) system and discharge the power when power demand is higher than the PV generated power. Diesel generator sets have also been used to run critical loads, provide reliability and as backup to critical operations catering for outages, night time needs and un-expected meteorological conditions. MATLAB has been used to design and simulate the proposed MG. Working of the MG has also been demonstrated for varying meteorological and varying load conditions as well. The proposed design works satisfactory in all cases.

scholarly journals Exergoeconomic and Normalized Sensitivity Analysis of Plate Heat Exchangers: A Theoretical Framework with Application

2021 ◽  
Author(s):  
Muhammad Ahmad Jamil ◽  
Talha S. Goraya ◽  
Haseeb Yaqoob ◽  
Kim Choon Ng ◽  
Muhammad Wakil Shahzad ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Heat Exchangers ◽  
Power Plants ◽  
Theoretical Framework ◽  
Plate Heat Exchanger ◽  
Sensitivity Analyses ◽  
Thermal Systems ◽  
Plate Heat ◽  
Economic Analyses ◽  
Exergoeconomic Analysis

Heat exchangers are the mainstay of thermal systems and have been extensively used in desalination systems, heating, cooling units, power plants, and energy recovery systems. This chapter demonstrates a robust theoretical framework for heat exchangers investigation based on two advanced tools, i.e., exergoeconomic analysis and Normalized Sensitivity Analysis. The former is applied as a mutual application of economic and thermodynamic analyses, which is much more impactful than the conventional thermodynamic and economic analyses. This is because it allows the investigation of combinatory effects of thermodynamic and fiscal parameters which are not achieved with the conventional methods. Similarly, the Normalized Sensitivity Analysis allows a one-on-one comparison of the sensitivity of output parameters to the input parameters with entirely different magnitudes on a common platform. This rationale comparison is obtained by normalizing the sensitivity coefficients by their nominal values, which is not possible with the conventional sensitivity analyses. An experimentally validated example of a plate heat exchanger is used to demonstrate the application of the proposed framework from a desalination system.

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