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<p><font face="Arial"> <p align="left">In this study, the capabilities of Neutron Radiography (NRad) and -Tomography (NTomo), as well as X-ray Radiography (XRad) to investigate chlorides and chlorides corrosion effects within steel reinforced laboratory concrete samples are practically explored. Capabilities of Scanning Electron Microscopy (SEM), Prompt Gamma Neutron Activation Analysis (PGNAA), Particle Induced X-ray Emission (PIXE), Small-Angle Neutron Scattering (SANS), Neutron Diffraction (NDIFF) and X-ray Diffraction (XDIFF) analytical techniques are also explored through review of literature.</p> </font></p>

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With an increase in the capabilities and sophistication of terrorist networks worldwide comes a corresponding increase in the probability of a radiological or nuclear device being detonated within the borders of the United States. One method to decrease the risk associated with this threat is to interdict the material during transport into the US. Current RPMS have limitations in their ability to detect shielded nuclear materials. It was proposed that directionally sensitive neutron detectors might be able to overcome many of these limitations. This thesis presents a method to create a directionally sensitive neutron detector using a unique characteristic of 10B. This characteristic is the Doppler broadening of the de-excitation gamma-ray from the 10B(n, alpha) reaction. Using conservation principles and the method of cone superposition, the mathematics for determining the incoming neutron direction vector from counts in a boron loaded cloud chamber and boron loaded semiconductor were derived. An external routine for MCNPX was developed to calculate the Doppler broaden de-excitation gamma-rays. The calculated spectrum of Doppler broadened de-excitation gamma-rays was then compared to measured and analytical spectrums and matched with a high degree of accuracy. MCNPX simulations were performed for both a prototype 10B loaded cloud chamber and prototype 10B loaded semiconductor detector. These simulations assessed the detectors' abilities to determine incoming neutron direction vectors using simulated particle reactant data. A sensitivity analysis was also performed by modifying the energy and direction vector of the simulated output data for 7Li* particles. Deviation coefficients showed a respective angular uncertainty of 1.86 degrees and 6.07 degrees for the boron loaded cloud chamber and a boron loaded semiconductor detectors. These capabilities were used to propose a possible RPM design that could be implemented.

Neutron scattering at extremes of pressure is a powerful tool for studying the response of structural and magnetic properties of materials on microscopic level to applied stresses. However, experimental neutron studies require a relatively large sample volume, which makes it necessary to use rather large presses. One of the most commonly used high-pressure devices in neutron diffraction experiments is the Paris-Edinburgh (P-E) press. This compact hydraulic press has been successfully used at various neutron facilities across the world for over 20 years. However, there are some limitations imposed by the design of the press and this project addressed two of them. The first objective of this research was to solve the problem of the spatial restriction on the scattered beam imposed by the tie-rods of the P-E press which results in the limited access to the reciprocal space of a single-crystalline sample. In order to overcome this challenge a rotating device has been designed and built to work with the existing P-E press mainframe. The purpose of the device is to rotate the anvils at a high load in a controlled fashion so that neutron diffraction data can be collected from the sample at particular angles. A number of technical challenges had to be overcome in the design process. One of the problems was caused by the significant friction in the commercially available thrust roller bearings at loads above 25 tonnes. To resolve this issue a set of custom-designed hydraulic bearings has been developed. In these bearings a thin layer of oil separates the two parts that can rotate with respect to each other.

Recent work by Yasseri and Rahnema has introduced a consistent spatial homogenization (CSH) method completely in transport theory. The CSH method can very accurately reproduce the heterogeneous flux shape and eigenvalue of a reactor, but at high computational cost. Other recent works for homogenization in diffusion or quasi-diffusion theory are accurate for problems with low heterogeneity, such as PWRs, but are not proven for more heterogeneous reactors such as BWRs or GCRs. To address these issues, a consistent hybrid diffusion-transport spatial homogenization (CHSH) method is developed as an extension of the CSH method that uses conventional flux weighted homogenized cross sections to calculate the heterogeneous solution. The whole-core homogenized transport calculation step of the CSH method has been replaced with a whole- core homogenized diffusion calculation. A whole-core diffusion calculation is a reasonable replacement for transport because the homogenization procedure tends to smear out transport effects at the core level. The CHSH solution procedure is to solve a core-level homogenized diffusion equation with the auxiliary source term and then to apply an on-the-fly transport-based re-homogenization at the assembly level to correct the homogenized and auxiliary cross sections. The method has been derived in general geometry with continuous energy, and it is implemented and tested in fine group, 1-D slab geometry on controlled and uncontrolled BWR and HTTR benchmark problems. The method converges to within 2% mean relative error for all four configurations tested and has computational efficiency 2 to 4 times faster than the reference calculation.

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Pseudo-plane strain compression tests are carried out on rolled plate Zircaloy-2 using different combinations of loaded and constrained sample directions relative to the plate principal directions. Lattice strains are measured for 17 out of 18 possible measureable sample directions. The inability to obtain true plane strain led to little effect of the compression rig on deformation during elastic loading; however noticeable differences are seen when compared to similar uniaxial data for Zircaloy-2 in the plastic region. Work hardening increased with increased constraint and was affected by the configuration of loaded and constrained sample directions. Constraint showed significant effects on twinning when twinning was present. For the RD loaded cases the initiation of twinning occurs at -318 MPa for the RD/ND case (RD loaded, ND constrained direction) and -420 MPa for the RD/TD case. Intensity profiles of the (0002) and {101 ̅ 0} indicate that more twinning occurs in the RD/TD case than the RD/ND case. For TD/YD an amplification of twinning was seen in the TD/RD when compared to the TD/ND. This is indicated both by texture results as well as the intensity profiles of the (0002) and {101 ̅ 0}. Using the experimental data an elastic-plastic self-consistent (EPSC) code was used to probe the micromechanical processes that are occurring when the compression rig is operated. The experimental data was used further to constrain the hardening parameters of the EPSC code using an inverse approach. The EPSC code was able to capture the relative activity of the twinning characteristics found by the experimental data but unable to truly capture the evolution of the (0002) lattice strains when twinning occurs. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2014-01-13 11:24:21.692