Nuclear Engineering Commons^™

Prediction Interval Estimation Techniques For Empirical Modeling Strategies And Their Applications To Signal Validation Tasks, Brandon Peter Rasmussen

Doctoral Dissertations

The basis of this work was to evaluate both parametric and non-parametric empirical modeling strategies applied to signal validation or on-line monitoring tasks. On-line monitoring methods assess signal channel performance to aid in making instrument calibration decisions, enabling the use of condition-based calibration schedules. The three non-linear empirical modeling strategies studied were: artificial neural networks (ANN), neural network partial least squares (NNPLS), and local polynomial regression (LPR). These three types are the most common nonlinear models for applications to signal validation tasks. Of the class of local polynomials (for LPR), two were studied in this work: zero-order (kernel regression), and …

Monte Carlo Simulation Of Neutron Detectors, Andrew Curtis Stephan

Doctoral Dissertations

Neutron detectors are simulated using Monte Carlo methods in order to gain insight into how they work and optimize their performance. Simulated results for a Micromegas neutron beam monitor using a custom computer code are compared with published experimental data to verify the accuracy of the simulation. Different designs (e.g. neutron converter material, gas chamber width, gas pressure) are tested to assess their impact on detector performance. It is determined that a ¹⁰B converter foil and 1 mm drift gap width work best for a neutron beam monitor. The Micromegas neutron beam monitor neutronics are evaluated using the computer …

Theoretical And Experimental Study Of Degradation Monitoring Of Steam Generators And Heat Exchangers, Xuedong Huang

Masters Theses

The objective of this research is focused on the modeling, analysis, and experimental study of steam generator and heat exchanger degradation monitoring and fault diagnosis. Experimental and analytical studies of tube fouling are performed and the system-level degradations are monitored using data-driven modeling of heat exchanger measurements. Initially, a comprehensive literature study was made on the steam generator and heat exchanger degradation types and mechanisms, including fouling and corrosion.

Based on the mass balance, energy balance, and momentum balance and the moving-boundary method, a multi-node SIMULINK model of a U-tube steam generator (UTSG) has been developed so as to simulate …

Burnable Poison Design For The International Reactor, Innovative And Secure (Iris), Allan Benton Wollaber

Masters Theses

The purpose of this research was to create computer models to expedite the core design of the International Reactor, Innovative and Secure (IRIS), specifically, so that it may employ burnable absorbers to achieve a longer cycle length and enhanced safety while minimizing the use of soluble boron. The IRIS is a next-generation, integral pressurized water reactor (PWR) being designed by an international consortium led by Westinghouse Electric. Two series of comparison benchmarks, defined by Westinghouse, were completed to validate computer models of representative pin cell, assembly, and whole core geometries. The models were created using the collision probability code HELIOS …

Learning From Data With Localized Regression And Differential Evolution, Mark A. Buckner

Doctoral Dissertations

Learning from data is fast becoming the rule rather than the exception for many science and engineering research problems, particularly those encountered in nuclear engineering. Problems associated with learning from data fall under the more general category of inverse problems. A data-drive inverse problem involves constructing a predictive model of a target system from a collection of input/output observations. One of the difficulties associated with constructing a model that approximates such unknown causes based solely on observations of their effects is that collinearities in the input data result in the problem being ill-posed. Ill-posed problems cause models obtained by …