This thesis presents methods for treating annihilation photon pairs in deterministic pulse height distribution (PHD) simulations. The methods are applied in PHD simulations for monoenergtic sources of 1.6 and 2.6 MeV photons incident on 5 and 10 cm 1-D slabs of germanium, sodium iodide, and lead and the results are...
The implementation of advanced hybrid (Monte Carlo/Deterministic) transport methods for realistic test problems has been a challenge due to the overhead efforts associated with interfacing a solution generated by a deterministic solver with a Monte Carlo based radiation transport code. In this work, with the help of Transpire, Inc., a...
A new method for accelerating the Upstream Corner Balance (UCB) discretization of the equation of transfer is introduced. The inconsistent acceleration equations for the UCB discretization are derived by applying the "Modified 4-Step" diffusion synthetic acceleration technique not to the UCB discretization, but instead to the simple corner balance (SCB)...
A hybrid Quasi-diffusion/Monte Carlo Method for solving multigroup criticality problems in slab geometry was investigated. Analog Monte Carlo was used to calculate functionals (Eddington Factors) that were then used in solution of the quasi-diffusion equations. The hybrid method was shown to accurately and precisely predict the k-eigenvalue and fission source...
Adjoint-derived weight windowing is a hybrid deterministic/Monte Carlo method to simulate radiation transport. In adjoint-derived weight windowing, a deterministic adjoint solution is used to create weight windows for a Monte Carlo simulation. The intent of this work is to identify factors that reduce the Figure of Merit (FOM) of Monte...
The intent of this work is to extend Implicit Monte Carlo Diffusion (IMD)[Gen.
2001] to account for frequency dependence and to incorporate the difference formulation[Szo. 2005] as a source manipulation variance reduction technique. This
work shows the derivation of the probabilities and the associated proofs which
govern the frequency dependent...
The high-order finite element S[subscript N] transport equations are solved on several test problems to investigate the behavior of the discretization method on meshes with curved edges in X-Y geometry. Simpler problems ensured the correct implementation of MFEM, the general fi nite element library employed. A convergence study using the...
For over 30 years, the Implicit Monte Carlo (IMC) method has been used to
solve challenging problems in thermal radiative transfer. These problems are typically optically thick and di ffusive, as a consequence of the high degree of "pseudo-scattering" introduced to model the absorption and reemission of photons from a...
One method of estimating the longwave radiative heating of the atmosphere is to combine satellite observations of emitted radiances with those computed from synoptic temperature and humidity profiles. Modeled and observed radiances are brought into agreement by altering cloud properties or even by adjusting the temperature and water vapor profiles....