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Titanium-Water Thermosyphon Gamma Radiation Exposure and ResultsTitanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some gamma irradiation. Noncondensable gas formation from radiation-induced breakdown of water over time may render portions of the thermosyphon condenser inoperable. A series of developmental thermosyphons were operated at nominal operating temperature under accelerated gamma irradiation, with exposures on the same order of magnitude as that expected in 8 years of heat rejection system operation. Temperature data were obtained during exposure at three locations on each thermosyphon: evaporator, condenser, and condenser end cap. Some noncondensable gas was evident; however, thermosyphon performance was not affected because the noncondensable gas was compressed into the fill tube region at the top of the thermosyphon, away from the heat rejecting fin. The trend appeared to be an increasing amount of noncondensable gas formation with increasing gamma irradiation dose. Hydrogen is thought to be the most likely candidate for the noncondensable gas and hydrogen is known to diffuse through grain boundaries. Post-exposure evaluation of one thermosyphon in a vacuum chamber and at temperature revealed that the noncondensable gas diffused out of the thermosyphon over a relatively short period of time. Further research shows a number of experimental and theoretical examples of radiolysis occurring through gamma radiation alone in pure water.
Document ID
20120015480
Document Type
Technical Memorandum (TM)
Authors
Sanzi, James, L.A (Sest, Inc. Middleburgh Heights, OH, United States)
Jaworske, Donald, A. (NASA Glenn Research Center Cleveland, OH, United States)
Goodenow, Debra, A. (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 26, 2013
Publication Date
September 1, 2012
Subject Category
Spacecraft Propulsion and Power
Report/Patent Number
AIAA Paper 2012-4078
NASA/TM-2012-217732
E-18229
Meeting Information
International Energy Conversion Engineering Conference(Atlanta, GA)
Funding Number(s)
WBS: WBS 887359.01.04
Distribution Limits
Public
Copyright
Public Use Permitted.

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