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Title: Laser ultrasonic assessment of the effects of porosity and microcracking on the elastic moduli of nuclear graphites

Abstract

Laser ultrasonic methods have been used to measure the elastic moduli of various nuclear graphites. Measurements were made to assess wavespeeds for longitudinal and shear waves in different propagation directions and these were used along with density measurements to compute the longitudinal and shear moduli as well as Young's modulus. All moduli decreased with increasing graphite porosity and these variations could be interpreted using models describing the effect of porosity on material stiffness. Extrapolations for these models to zero porosity were used to infer the moduli for theoretically dense graphite; the results were far below predicted values reported in the literature for fully dense, polycrystalline, isotropic graphite. Differences can be attributed to microcracking in the graphite microstructure. Using models for the effects of microcracking on modulus, estimates for microcrack populations indicate that the number of cracks per unit volume must be much greater than the number of pores per unit volume. Experimental results reported in the literature for irradiated graphites as well as for the stress dependence of graphite modulus are consistent with the influence of microcracking on elastic behavior and could be interpreted using concepts developed here. In conclusion, results in this work for graphite structure- property relationships shouldmore » allow for more sophisticated characterization of nuclear graphites using ultrasonic methods.« less

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [2];  [2]
  1. Johns Hopkins Univ., Baltimore, MD (United States). Department of Materials Science and Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE). Nuclear Energy University Program (NEUP); Work for Others (WFO)
OSTI Identifier:
1364292
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 471; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 36 MATERIALS SCIENCE; Laser ultrasonics; Nuclear graphite; Porosity; Microcracking

Citation Formats

Spicer, James B., Olasov, Lauren R., Zeng, Fan W., Han, Karen, Gallego, Nidia C., and Contescu, Cristian I. Laser ultrasonic assessment of the effects of porosity and microcracking on the elastic moduli of nuclear graphites. United States: N. p., 2015. Web. doi:10.1016/j.jnucmat.2015.12.015.
Spicer, James B., Olasov, Lauren R., Zeng, Fan W., Han, Karen, Gallego, Nidia C., & Contescu, Cristian I. Laser ultrasonic assessment of the effects of porosity and microcracking on the elastic moduli of nuclear graphites. United States. https://doi.org/10.1016/j.jnucmat.2015.12.015
Spicer, James B., Olasov, Lauren R., Zeng, Fan W., Han, Karen, Gallego, Nidia C., and Contescu, Cristian I. Thu . "Laser ultrasonic assessment of the effects of porosity and microcracking on the elastic moduli of nuclear graphites". United States. https://doi.org/10.1016/j.jnucmat.2015.12.015.
@article{osti_1364292,
title = {Laser ultrasonic assessment of the effects of porosity and microcracking on the elastic moduli of nuclear graphites},
author = {Spicer, James B. and Olasov, Lauren R. and Zeng, Fan W. and Han, Karen and Gallego, Nidia C. and Contescu, Cristian I.},
abstractNote = {Laser ultrasonic methods have been used to measure the elastic moduli of various nuclear graphites. Measurements were made to assess wavespeeds for longitudinal and shear waves in different propagation directions and these were used along with density measurements to compute the longitudinal and shear moduli as well as Young's modulus. All moduli decreased with increasing graphite porosity and these variations could be interpreted using models describing the effect of porosity on material stiffness. Extrapolations for these models to zero porosity were used to infer the moduli for theoretically dense graphite; the results were far below predicted values reported in the literature for fully dense, polycrystalline, isotropic graphite. Differences can be attributed to microcracking in the graphite microstructure. Using models for the effects of microcracking on modulus, estimates for microcrack populations indicate that the number of cracks per unit volume must be much greater than the number of pores per unit volume. Experimental results reported in the literature for irradiated graphites as well as for the stress dependence of graphite modulus are consistent with the influence of microcracking on elastic behavior and could be interpreted using concepts developed here. In conclusion, results in this work for graphite structure- property relationships should allow for more sophisticated characterization of nuclear graphites using ultrasonic methods.},
doi = {10.1016/j.jnucmat.2015.12.015},
url = {https://www.osti.gov/biblio/1364292}, journal = {Journal of Nuclear Materials},
issn = {0022-3115},
number = C,
volume = 471,
place = {United States},
year = {2015},
month = {12}
}