Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2001. / Includes bibliographical references (p. 139-143). / The purpose of this work is to evaluate the potential for enhancing the performance of the once-through PWR fuel cycle by appropriate design of thorium containing fuel with concurrent consideration of neutronics, thermal-hydraulics, and proliferation resistance. CASMO-4 is employed to model a fuel assembly consisting of a homogeneously fueled ThO2-UO2 lattice of conventional design. It is found that homogeneously mixed ThO2-UO2 fuel in general has better physics behavior than all-UO2 fuel, e.g. more negative MTC and less reactivity swing. The H/HM ratio can be optimized to extend the burnup of both ThO2-UO2 and all-UO2 fuel about 10% and 5% respectively. However, it is found that the all-UO2 fuel provides higher potential energy generation (or achievable burnup) than the homogeneously mixed ThO2-UO2 fuel. MOCUP (MCNP+ORIGEN) is used to model unit cells of the micro-heterogeneous fuel. The key findings for the best micro-heterogeneous configurations are as follows: (1) For a given U-235 inventory, a 20% to 30% increase in fuel cycle achievable bumup above the homogeneous case is possible, therefore 10% to 15% above the all-UO2 fuel; (2) For certain axially heterogeneous configurations, a "burnable poison" reactivity suppression effect appears at the beginning of irradiation. Analysis of the possible mechanisms behind these effects shows that they are due to a combination of changes in self-shielding, local fissile worth, and conversion ratio. / (cont.) Economic evaluations show that the homogeneous ThO2-UO2 fuel is 20%-30% more expensive than the equivalent all-U fuel but micro-heterogeneous fuel can be comparable to or even cheaper than the all-UO2 fuel. In terms of the plutonium content, the micro-heterogeneous Th/U fuel is more proliferation-resistant than the homogeneous Th/U fuel, and the homogeneous Th/U fuel is more proliferation-resistant than the all-UO2 fuel. However, the uranium produced in the ThO2 zone of any undenatured micro-heterogeneous design should be considered of proliferative concern. Adding natural or depleted uranium to the ThO2 zone can make the material not weapon-usable at the expense of degrading the neutronic performance. Placing some enriched uranium within the thorium zone may be needed to reduce local thermal peaking to a manageable level. / by Xiaofeng Zhao. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1998. / Includes bibliographical references (p. 162-174). / by Rena Jae Lee. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1997. / Includes bibliographical references (p. 189-194). / by Daniel Hung Chee Lo. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1997. / Includes bibliographical references (p. 91-92). / by Aaron John Allen. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1994. / Includes bibliographical references (leaves 200-205). / by John A. Urbahn. / Ph.D.

Includes bibliographical references (p. 167-168). / Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995. / by Sangman Kwak. / Sc.D.

Massachusetts Institute of Technology. Dept. of Nuclear Engineering. Thesis. 1974. M.S. / Includes bibliographical references. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1991. / Includes bibliographical references (leaves 330-337). / by Scott Y. Peng. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1991. / Includes bibliographical references (leaves 149-153). / by Jerry Lynn Martin. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1985. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Bibliography: leaves 118-121. / by Kirby Burkholder. / M.S.