Micro-heterogeneous thorium based fuel concepts for pressurized water reactions

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.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Nuclear Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Zhao, Xianfeng, 1971-

Advisor dc:contributor.advisor

• Michael J. Driscoll.

• Nuclear Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/8680

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8680