Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1994. / Includes bibliographical references. / by Jeffrey R. O'Donnell. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1987. / Bibliography: v. 2, leaves 498-511. / by Il Soon Hwang. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1992. / Includes bibliographical references (leaves 133-140). / by Riccardo Betti. / Ph.D.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2004. / Includes bibliographical references (leaves 83-85). / Nuclear materials and their uses are regulated differently in countries around the world. In the United States, the Nuclear Regulatory Commission regulates the different commercial and academic uses of nuclear technology, including nuclear power plants. In France, the Direction Generale de la Surete Nucleaire et de la Radioprotection (DGSNR) and the Electricite de France (EDF) control the nuclear industry, with the DGSNR controlling most of the regulation and the EDF presiding over the construction. In this thesis, the two systems of regulation will be reviewed and compared for efficiency and efficacy. Furthermore, those efficiencies will be examined for implications in the technical, social, and economic regimes. This thesis will review the histories and present-day structures of two different regulatory agencies, propose reasons for the difference, and argue the benefits and shortcomings of each. At first glance, the American regulatory system appears to be in the hands of the lawmakers and founded on a legal basis. The French system, however, emphasizes the scientists and engineers as the regulatory experts and is thus founded more on a scientific and technical foundation. / by Matthew D. Aichele. / S.B.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2004. / Includes bibliographical references (p. 77-79). / Initial plasma experiments in the Levitated Dipole Experiment focus on producing hot electron, high beta plasmas using a supported dipole configuration. Plasmas are created using multifrequency ECRH and it is therefore expected that most of the plasma energy will be stored in the fast electrons, Te > 100 keV. As a consequence, x-ray flux from bremsstrahlung emission is expected to be easily detectable. The energy spectrum of the x-ray emission below 740 keV is measured by a four channel pulse height analyzer using cadmium zinc telluride detectors. In addition, a single sodium iodide detector, which views energies up to 3 MeV, measures the intensity of the hot electron population. The electron temperature may be inferred from the x-ray energy. X-ray measurements are essential in diagnosing the effectiveness of various ECRH configurations. The design and installation of the pulse height analyzer are discussed in addition to the preliminary results from first plasma experiments. / by Jennifer L. Ellsworth. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2005. / Includes bibliographical references (leaves 195-200). / A new approach to the detection of concealed nuclear weapons and fissile material aboard cargo containerships is proposed. The ship-based approach removes the constraints of current thinking by addressing the threat of containerized nuclear terror in a novel way. Critical tactical misjudgments exist in currently deployed detection systems, which expose U.S. cities to an act of nuclear terrorism. Current port-based systems position defenses within the perimeter of each coastal city and the assumption that terrorists would not remotely detonate the weapon while taxiing past urban areas en route to the port is irrational. The new approach protects this hole in national security by moving defenses outside the perimeter and onto the containership. A networked system of radiation detectors, aboard all inbound containerships, does not allow a concealed nuclear weapon to ever approach the U.S. homeland. This thesis describes the ship-based system in detail, outlines its capabilities and suggests possible deployment scenarios. The basic concept of the ship-based system is to hide detectors in empty standard 40-foot shipping containers and send them back and forth across the ocean alongside normal cargo. Containerized arrays of gamma and neutron detectors are linked to small data processing and transmitting devices. / (cont.) Data is transmitted to a central U.S. location for collection, assessment, and possible dissemination to responders in the event of threat identification. Upon positive detection, an alarm condition is signaled and interception of the containership occurs while still at sea. Monte Carlo based simulations suggest that due to long count times during typical two week voyages, radiation transport is significant enough such that containerized units will detect weapons grade uranium and plutonium in implosion-type configurations with three-sigma confidence from distances averaging 22.0 and 23.5 meters of cargo respectively. The vast majority of containerships require between 3 and 15 units deployed on each ship depending on its capacity and degree of control over container placement. Given the low number of units required for each ship, deployment of a containerized detector network is practical and an initial limited deployment increases the level of deterrence by, denial against containerized nuclear terror. / by Shawn P. Gallagher. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2005. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 265-271). / A ten channel Motional Stark Effect diagnostic has been installed on Alcator C-Mod to measure the plasma internal magnetic pitch angle profile. The C-Mod MSE measures the local electric field direction by measuring the polarization angle of Balmer-[alpha] n=2) emission from a radially injected hydrogen Diagnostic Neutral Beam (50 keV, 5 A, 50 ms). The Lorentz electric field (EL = v ) and the magnetic field cause the nominally fully degenerate Balmer-[alpha] to split into a partially degenerate multiplet whose components are polarized relative to the local fields. Through careful spectral filtering, MSE measures the polarization angle of select multiplet components using a photoelastic modulator based polarimeter. Investigation of hydrogenic Balmer-[alpha] transitions in crossed E and B fields typical of MSE has led to the discovery of new features of the Stark-Zeeman Balmer-[alpha] multiplet. Three different transitions are found for this EB = ( ... ) configuration. In the regime where the Stark effect dominates over the Zeeman effect, transitions polarize parallel to E, B, or ... with ellipticity a function of the beam velocity. More important for MSE diagnostics is the discovery that multiplet lines (summed over degenerate transitions) will be observed to be orthogonally polarized only for statistical (i.e. equally) upper hybrid state populations. / (cont.) This contradicts the pure Stark case that is typically assumed for MSE, where Stark- lines are always observed to be orthogonal to Stark-[pi] lines. Non-statistical upper hybrid states populations are expected in certain situations including the propagation of beam neutrals through neutral gas, which is often used to calibrate MSE diagnostics in situ. Implementation of MSE on C-Mod required significant optical and optomechanical engineering. Satisfying MSE viewing geometry requirements for a radial beam on C-Mod resulted in an extended periscope inside the vacuum vessel. A successful design with robust performance against disruption accelerations, fatigue, creep, thermal stresses, and impact while being vacuum compatible has been developed for mounting the necessary polarization preserving optics. Full Stokes polarimeter modeling and calibration has been performed for the C-Mod MSE. An invessel apparatus has been constructed that is capable of generating pure, linearly polarized light absolutely aligned (to gravity) at arbitrary angles,circularly polarized light, as well as unpolarized light. This device has been used in situ to measure the MSE response to all possible Stokes vectors. Results have been compared to a Mueller matrix model of MSE including real geometry and one imperfect mirror with an arbitrary s&p phase shift and s&p reflectivity ratio. / (cont.) Geometric and optical properties of MSE have been deduced by matching measured responses with modeled responses. A method for concurrently measuring the PEM retardances has been developed as part of this effort. A complementary calibration technique using DNB injection into a gas-filled torus with known fields capable of measuring in situ optical Faraday rotation was also performed. Results show possible molecular deuterium contamination arising from the fill gas used in the calibration. MSE polarization measurements displayed discrepancies of over 20 with expected values from a vacuum field reconstruction. Motivated by spectral observations, an inclusion of Zeeman polarized D2 molecular emission reconciled measured and modeled values of the linear angle and polarization fraction. Observed on-linearities in angular response and the strong viewing geometry dependency are also reproduced in the model when Zeeman polarized D2 emission is included. Experiments testing this hypothesis are proposed. Pitch angle measurements in plasmas show that MSE has statistical uncertainties of 0.4 for all but the edge channel up to plasma densities of ne = 1.5 x 1020 m-3. This is insufficient to explain remaining discrepancies with magnetic reconstruction results at the plasma edge. While Faraday rotation and PEM retardance changes could play a role, these instrumental effects are also insufficient. Radial electric fields and beam induced charge exchange emission have been suggested as causes for errors in MSE measurements of plasma. / by Howard Yung-Hao Yuh. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995. / Includes bibliographical references (leaves 113-115). / by Tamer Bahadir. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995. / Includes bibliographical references (p. 76-78). / by Brett T. Mattingly. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1996. / Includes bibliographical references (leaves 124-125). / by Hideki Masui. / M.S.