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Title: Characterization of nuclear graphite elastic properties using laser ultrasonic methods

Abstract

Laser ultrasonic methods have been used to characterize the elastic behaviors of commercially-available and legacy nuclear graphites. Since ultrasonic techniques are sensitive to various aspects of graphite microstructure including preferred grain orientation, microcrack orientation and porosity, laser ultrasonics is a candidate technique for monitoring graphite degradation and structural integrity in environments expected in high-temperature, gas-cooled nuclear reactors. Aspects of materials texture can be assessed by studying ultrasonic wavespeeds as a function of propagation direction and polarization. Shear wave birefringence measurements, in particular, can be used to evaluate elastic anisotropy. In this work, laser ultrasonic measurements of graphite moduli have been made to provide insight into the relationship between the microstructures and the macroscopic stiffnesses of these materials. In particular, laser ultrasonic measurements have been made using laser line sources to produce shear waves with specific polarizations. By varying the line orientation relative to the sample, shear wave birefringence measurements have been recorded. Results from shear wave birefringence measurements show that an isostatically molded graphite, such as PCIB, behaves isotropically, while an extruded graphite, such as H-451, displays significant ultrasonic texture. Graphites have complicated microstructures that depend on the manufacturing processes used, and ultrasonic texture in these materials could originate frommore » grain orientation and preferred microcrack alignment. Effects on material isotropy due to service related microstructural changes are possible and the ultimate aim of this work is to determine the degree to which these changes can be assessed nondestructively using laser ultrasonics measurements« less

Authors:
 [1];  [1];  [1];  [2];  [2];  [1]
  1. Johns Hopkins University
  2. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
Work for Others (WFO)
OSTI Identifier:
1265680
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: SPIE 2015, Baltimore, MD, USA, 20150512, 20150512
Country of Publication:
United States
Language:
English
Subject:
graphite; texture; laser ultrasonics; shear wave; shear modulus; anisotropy

Citation Formats

Zeng, Fan W, Han, Karen, Olasov, Lauren R, Gallego, Nidia C, Contescu, Cristian I, and Spicer, James B. Characterization of nuclear graphite elastic properties using laser ultrasonic methods. United States: N. p., 2015. Web.
Zeng, Fan W, Han, Karen, Olasov, Lauren R, Gallego, Nidia C, Contescu, Cristian I, & Spicer, James B. Characterization of nuclear graphite elastic properties using laser ultrasonic methods. United States.
Zeng, Fan W, Han, Karen, Olasov, Lauren R, Gallego, Nidia C, Contescu, Cristian I, and Spicer, James B. Thu . "Characterization of nuclear graphite elastic properties using laser ultrasonic methods". United States. doi:.
@article{osti_1265680,
title = {Characterization of nuclear graphite elastic properties using laser ultrasonic methods},
author = {Zeng, Fan W and Han, Karen and Olasov, Lauren R and Gallego, Nidia C and Contescu, Cristian I and Spicer, James B},
abstractNote = {Laser ultrasonic methods have been used to characterize the elastic behaviors of commercially-available and legacy nuclear graphites. Since ultrasonic techniques are sensitive to various aspects of graphite microstructure including preferred grain orientation, microcrack orientation and porosity, laser ultrasonics is a candidate technique for monitoring graphite degradation and structural integrity in environments expected in high-temperature, gas-cooled nuclear reactors. Aspects of materials texture can be assessed by studying ultrasonic wavespeeds as a function of propagation direction and polarization. Shear wave birefringence measurements, in particular, can be used to evaluate elastic anisotropy. In this work, laser ultrasonic measurements of graphite moduli have been made to provide insight into the relationship between the microstructures and the macroscopic stiffnesses of these materials. In particular, laser ultrasonic measurements have been made using laser line sources to produce shear waves with specific polarizations. By varying the line orientation relative to the sample, shear wave birefringence measurements have been recorded. Results from shear wave birefringence measurements show that an isostatically molded graphite, such as PCIB, behaves isotropically, while an extruded graphite, such as H-451, displays significant ultrasonic texture. Graphites have complicated microstructures that depend on the manufacturing processes used, and ultrasonic texture in these materials could originate from grain orientation and preferred microcrack alignment. Effects on material isotropy due to service related microstructural changes are possible and the ultimate aim of this work is to determine the degree to which these changes can be assessed nondestructively using laser ultrasonics measurements},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jan 01 00:00:00 EST 2015},
month = {Thu Jan 01 00:00:00 EST 2015}
}

Conference:
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