Micro-porous coatings and enhanced chf for downward facing boiling during passive emergency reactor cooling

Albert E. Segall, Faruk A. Sohag, Faith R. Beck, Lokanath Mohanta, Fan Bill Cheung, Timothy J. Eden, John Potter

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

During a Reaction Initiated Accident (RIA) or Loss of Coolant Accident (LOCA), passive external-cooling of the reactor lower head is a viable approach for the in-vessel retention of Corium; while this concept can certainly be applied to new constructions, it may also be viable for operational systems with existing cavities below the reactor. However, a boiling crisis will inevitably develop on the reactor lower head owing to the occurrence of Critical Heat Flux or CHF that could reduce the decay heat removal capability as the vapor phase impedes continuous boiling. Fortunately, this effect can be minimized for both new and existing reactors through the use of a Cold-Spray delivered, micro-porous coating that facilitates the formation of vapor micro-jets from the reactor surface. The micro-porous coatings were created by first spraying a binary mixture with the sacrificial material then removed via etching. Subsequent quenching experiments on uncoated and coated hemispherical surfaces showed that local CHF values for the coated vessel were consistently higher relative to the bare surface. Moreover, it was observed for both coated and uncoated surfaces that the local rate of boiling and local CHF limit varied appreciably along the outer surface. Nevertheless, the results of this intriguing study clearly show that the use of Cold Spray coatings could enhance the local CHF limit for downward facing boiling by more than 88%. Moreover, the Cold-Spray process is amenable to coating the lower heads of operating reactors.

Original languageEnglish (US)
Title of host publicationDesign and Analysis
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791850398
DOIs
StatePublished - Jan 1 2016
EventASME 2016 Pressure Vessels and Piping Conference, PVP 2016 - Vancouver, Canada
Duration: Jul 17 2016Jul 21 2016

Publication series

NameAmerican Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
Volume3
ISSN (Print)0277-027X

Other

OtherASME 2016 Pressure Vessels and Piping Conference, PVP 2016
CountryCanada
CityVancouver
Period7/17/167/21/16

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All Science Journal Classification (ASJC) codes

  • Mechanical Engineering

Cite this

Segall, A. E., Sohag, F. A., Beck, F. R., Mohanta, L., Cheung, F. B., Eden, T. J., & Potter, J. (2016). Micro-porous coatings and enhanced chf for downward facing boiling during passive emergency reactor cooling. In Design and Analysis [V003T03A088] (American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP; Vol. 3). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/PVP2016-63014