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The Effects Of A Power Iteration-Based K-Eigenvalue Solver For Various Subcritical Parameters And Calculations, Daniel H. Timmons

Nuclear Engineering ETDs

The need to simulate subcritical benchmark parameters quickly and accurately is becoming increasing important. When using Monte Carlo methods this is traditionally done using a fixed-source calculation where a particle and its progeny are tracked until their removal from the system. This method can be slow for near critical systems. The use of a k-eigenvalue solver could reduce the computational footprint and reduce the need to post process data.

This is done for four parameters from the ICSBEP benchmark values: R_1 , R_2 , M_L, and M_eff. These parameters are calculated in two new distinct ways. First, is directly …

Monte Carlo Perturbation Analysis Of Fuel Temperature Variations In The Mcnp Model Of The Annular Core Research Reactor, Melissa Andrea Moreno

Nuclear Engineering ETDs

The Annular Core Research Reactor (ACRR) Monte Carlo N-Particle (MCNP) model is used for a variety of computational calculations ranging from reactor kinetics metrics to safety analyses. To understand the dominant source of uncertainty within the model, perturbations in temperature were applied to individual ACRR MCNP fuel rods. Assigning random temperatures, selected uniformly, from the operational temperature ranges of the fuel enables a study of uncertainty effects based on temperature variations. Stochastic mixing was used to blend the cross-sections of the desired temperatures using the MCNP continuous and Thermal Neutron Scattering Treatment (S(α,β)) libraries in ENDF/B-VII.1. The uncertainty quantification process …

Characterization Of Uranium Foil Irradiations At The Wsu Triga Reactor Using A New Reactor Model In Scale, Kimberly A. Hinrichs

Nuclear Engineering ETDs

A new reactor model of the Washington State University TRIGA was developed in the SCALE neutron transport code, and its fidelity was verified by comparison to MCNP and available data for several reactor parameters. The model was used to characterize irradiations designed to produce the short-lived actinides ²³⁷U and ²³⁹U, two key isotopes for nuclear forensics. These short-lived actinides, their decay daughters ²³⁷Np and ²³⁹Pu, and total fissions (via ⁹⁹Mo) were measured in irradiated foils at Los Alamos National Laboratory and other labs with good agreement among parent/daughter pairs and among labs. The laboratory-measured isotope …

Time And Energy Characterization Of A Neutron Time Of Flight Detector Using A Novel Coincidence Method For Constraining Neutron Yield, Ion Temperature And Liner Density Measurements From Maglif Experiments, Jedediah Styron

Nuclear Engineering ETDs

The focus of this work is the characterization of a typical neutron time-of-flight (NTOF) detector that is fielded on inertial confinement fusion (ICF) experiments conducted at the Z-experimental facility with emphasis on the Magnetized Liner Fusion (MagLIF) concept. An NTOF detector consisting of EJ-228 scintillator and two independent photomultiplier tubes (PMTs), a Hamamatsu-mod 5 and Photek-PMT240, has been characterized in terms of the absolute time and energy response. The characterization was done by measuring single, neutron-induced events in the scintillator by measuring the alpha particle and neutron produced from the D-T reaction in kinematic coincidence. The results of these experiments …

Doppler Temperature Coefficient Calculations Using Adjoint-Weighted Tallies And Continuous-Energy Cross Sections In Mcnp6, Matthew A. Gonzales

Nuclear Engineering ETDs

The calculation of the thermal neutron Doppler temperature reactivity feedback co- efficient, a key parameter in the design and safe operation of advanced reactors, using first order perturbation theory in continuous energy Monte Carlo codes is challenging as the continuous energy adjoint flux is not readily available. Traditional approaches of obtaining the adjoint flux attempt to invert the random walk process as well as require data corresponding to all temperatures and their respective tem- perature derivatives within the system in order to accurately calculate the Doppler temperature feedback.

A new method has been developed using adjoint-weighted tallies and On-The-Fly (OTF) …