On the use of high performance annular fuel in PWRs

Recently, MIT's Center for Advanced Nuclear Energy Systems developed a new high burnup annular fuel that features both internal and external cooling. Implementation of this fuel design in current pressurized water reactors (PWRs) will allow power uprates up to 50% while maintaining or improving its existing thermal and safety margins. Each annular fuel assembly is arranged in a 13x13 array but has the same side dimensions as a 17x17 solid fuel assembly. Even at much higher power densities, the peak fuel temperatures are substantially lower and the MDNBR is comparable to that of solid fuel at 100% power. The main motivation for utilizing this fuel is the lower capital construction cost per kilowatt of electrical production compared to new reactors using solid fuel. To elaborate on the previous work, three remaining issues were addressed: the shutdown margin deficiency at 50% uprated power, effect of inner channel flow restrictions due to crud buildup and obstructions, and the economic impact of a fleet of reactors using high burnup annular fuel. All of the work was done using computer codes specializing in core neutronics, thermal hydraulics, and fuel cycle analysis. The reduced shutdown margin was found to be caused mainly by a reduction in control material volume coupled with a higher power density. This issue was resolved by changing the control material from traditional Ag-In-Cd to 25 wt% B-10 enriched B₄C. Increasing the control rod surface area was also investigated as a possible solution but it was revealed that any departure from the cylindrical shape would lead to a reduction in control volume which resulted in decreased rod worth. Simultaneous oxide growth and crud buildup on the inner cladding of the annular fuel was simulated in a whole core thermal-hydraulics model to determine the maximum thickness that the annular fuel can tolerate while maintaining an MDNBR greater than 1.3 under transient overpower conditions.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Nuclear Science and Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Feng, Bo, 1971-

Advisor dc:contributor.advisor

• Mujid S. Kazimi.

• Nuclear Science and 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/1721.1/44791

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/44791