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Title: Oxidation of PCEA nuclear graphite by low water concentrations in helium

Accelerated oxidation tests were performed to determine kinetic parameters of the chronic oxidation reaction of PCEA graphite in contact with helium coolant containing low moisture concentrations in high temperature gas-cooled reactors. To the authors best knowledge such a study has not been done since the detailed analysis of reaction of H-451 graphite with steam [Velasquez, Hightower, Burnette, 1978]. Since that H-451 graphite is now unavailable, it is urgently needed to characterize chronic oxidation behavior of new graphite grades under qualification for gas-cooled reactors. The Langmuir-Hinshelwood mechanism of carbon oxidation by water results in a non-linear reaction rate expression, with at least six different parameters. They were determined in accelerated oxidation experiments that covered a large range of temperatures (800 to 1100 oC), and partial pressures of water (15 to 850 Pa) and hydrogen (30 to 150 Pa) and used graphite specimens thin enough (4 mm) in order to avoid diffusion effects. Data analysis employed a statistical method based on multiple likelihood estimation of parameters and simultaneous fitting of non-linear equations. The results show significant material-specific differences between graphite grades PCEA and H-451 which were attributed to microstructural dissimilarity of the two materials. It is concluded that kinetic data cannot bemore » transferred from one graphite grade to another.« less
 [1] ;  [2] ;  [1] ;  [3] ;  [1]
  1. ORNL
  2. University of Tennessee (UT)
  3. University of Tennessee, Knoxville (UTK)
Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Nuclear Materials; Journal Volume: 453; Journal Issue: 1-3
Research Org:
Oak Ridge National Laboratory (ORNL)
Sponsoring Org:
ORNL work for others
Country of Publication:
United States
WATER; STEAM; KINETICS Nuclear graphite; chronic oxidation; water; steam; kinetics