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A Comparison of Materials Issues for Cermet and Graphite-Based NTP FuelsThis paper compares material issues for cermet and graphite fuel elements. In particular, two issues in NTP fuel element performance are considered here: ductile to brittle transition in relation to crack propagation, and orificing individual coolant channels in fuel elements. Their relevance to fuel element performance is supported by considering material properties, experimental data, and results from multidisciplinary fluid/thermal/structural simulations. Ductile to brittle transition results in a fuel element region prone to brittle fracture under stress, while outside this region, stresses lead to deformation and resilience under stress. Poor coolant distribution between fuel element channels can increase stresses in certain channels. NERVA fuel element experimental results are consistent with this interpretation. An understanding of these mechanisms will help interpret fuel element testing results.
Document ID
Document Type
Conference Paper
Stewart, Mark E. (Vantage Partners, LLC Brook Park, OH, United States)
Schnitzler, Bruce G. (Oak Ridge National Lab. TN, United States)
Date Acquired
August 13, 2014
Publication Date
June 24, 2013
Subject Category
Spacecraft Propulsion and Power
Propellants and Fuels
Report/Patent Number
Meeting Information
AIAA Annual Joint Propulsion Conference(San Jose, CA)
Funding Number(s)
WBS: WBS 279585.04.02.22
Distribution Limits
Public Use Permitted.
Nuclear Propulsion
Mathematical Models
Fracture Mechanics

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