Controlling CRUD vapor chimney formation in LWRs through surface modification

Fouling has been a persistent problem for fluid-solid interfaces, varying from heat exchangers to ship hulls. In nuclear power plants, buildup of CRUD can accelerate corrosion, increase pressure drops, cause axial power shifts, and increase radiation dose to workers. In this experiment, we studied the effect of induced microcavity and micropost patterns on CRUD morphology at atmospheric pressure. Samples with various pitches of microcavities and microposts were boiled in simulated PWR coolant. The effect of heat flux on CRUD formation was also examined. The experiments support previous theories that subcooled nucleate boiling is enhanced at microcavities, and that CRUD deposition is promoted at those sites. A thin ring of particles, less than a micrometer in width, was seen around most microcavities even when the surrounding areas were crudded. However, some of the samples with microcavity pitches 50 pm and smaller experienced a pattern of clean and crudded areas, with the region around the microcavities free of CRUD more often than not. A theory is put forth that this is caused by interfering forces due to bubbles collapsing. The micropost samples showed substantial CRUD growth, particularly for the sample subjected to a high heat flux. The results of this experiment could have major implications for development of a self-cleaning material for heated surfaces.

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

2014

Author dc:creator

• Lin, Leigh

Advisor dc:contributor.advisor

• Michael P. Short.

• 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/1721.1/95594

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/95594