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Title: APT Characterization of Irradiated High Nickel RPV Steels

Authors:
 [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shared Research Equipment Collaborative Research Center
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931780
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Nuclear Materials; Journal Volume: 361
Country of Publication:
United States
Language:
English

Citation Formats

Miller, Michael K, Russell, Kaye F, Sokolov, Mikhail A, and Nanstad, Randy K. APT Characterization of Irradiated High Nickel RPV Steels. United States: N. p., 2007. Web. doi:10.1016/j.jnucmat.2006.12.015.
Miller, Michael K, Russell, Kaye F, Sokolov, Mikhail A, & Nanstad, Randy K. APT Characterization of Irradiated High Nickel RPV Steels. United States. doi:10.1016/j.jnucmat.2006.12.015.
Miller, Michael K, Russell, Kaye F, Sokolov, Mikhail A, and Nanstad, Randy K. Mon . "APT Characterization of Irradiated High Nickel RPV Steels". United States. doi:10.1016/j.jnucmat.2006.12.015.
@article{osti_931780,
title = {APT Characterization of Irradiated High Nickel RPV Steels},
author = {Miller, Michael K and Russell, Kaye F and Sokolov, Mikhail A and Nanstad, Randy K},
abstractNote = {},
doi = {10.1016/j.jnucmat.2006.12.015},
journal = {Journal of Nuclear Materials},
number = ,
volume = 361,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The planned life extension of nuclear reactors throughout the US and abroad will cause reactor vessel and internals materials to be exposed to more neutron irradiation than was originally intended. A nondestructive evaluation (NDE) method to monitor radiation damage would enable safe and cost-effective continued operation of nuclear reactors. Radiation damage in reactor pressure vessel (RPV) steels causes microstructural changes that leave the material in an embrittled state. Nonlinear ultrasound is an NDE technique quantified by the measurable acoustic nonlinearity parameter, which is sensitive to microstructural changes in metallic materials such as dislocations, precipitates and their combinations. Recent research hasmore » demonstrated the sensitivity of the acoustic nonlinearity parameter to increasing neutron fluence in representative RPV steels. The current work considers nonlinear ultrasonic experiments conducted on similar RPV steel samples that had a combination of irradiation, annealing, re-irradiation, and/or re-annealing to a total neutron fluence of 0.5 5 1019 n/cm2 (E > 1 MeV) at an irradiation temperature of 290 C. The acoustic nonlinearity parameter generally increased with increasing neutron fluence, and consistently decreased from the irradiated to the annealed state over different levels of neutron fluence. Results of the measured acoustic nonlinearity parameter are compared with those from previous measurements on other RPV steel samples. This comprehensive set of results illustrates the dependence of the measured acoustic nonlinearity parameter on neutron fluence, material composition, irradiation temperature and annealing.« less
  • Atom probe tomography has played a key role in the understanding of the embrittlement of neutron irradiated reactor pressure vessel steels through the atomic level characterization of the microstructure. Atom probe tomography has been used to demonstrate the importance of the post weld stress relief treatment in reducing the matrix copper content in high copper alloys, the formation of {approx}-nm-diameter copper-, nickel-, manganese- and silicon-enriched precipitates during neutron irradiation in copper containing RPV steels, and the coarsening of these precipitates during post irradiation heat treatments. Atom probe tomography has been used to detect {approx}2-nm-diameter nickel-, silicon- and manganese-enriched clusters inmore » neutron irradiated low copper and copper free alloys. Atom probe tomography has also been used to quantify solute segregation to, and precipitation on, dislocations and grain boundaries.« less
  • Moessbauer spectroscopy (MS) and Positron annihilation spectroscopy (PAS) were applied in the evaluation of the microstructure parameters and degradation processes of nuclear reactor pressure vessel (RPV) steel surveillance specimens. Study was oriented to the material investigation of Russian WWER-1000 steels (15Kh2MNFAA and 12Kh2N2MAA) with higher Ni content (1.26 wt.% in base metal and 1.7 wt.% in weld). For comparison, the WWER-440 weld metal (Sv10KhMFT) without Ni was measured too. Specimens were studied in as received form, after irradiation in LVR-15 experimental reactor to the neutron fluence F(E>0.5 MeV) = 1.47x1024 m-2s-1 and after annealing process in vacuum at 475 deg.more » C/2h. Changes due to different chemical composition and due to irradiation were registered using MS. Post-irradiation thermal treatment and annealing of defects was well detected by different PAS techniques. Results confirm the hypothesis that Ni affects size (decrease) and distribution (more homogeneous) of the Cu- and P-rich clusters and MxCx carbides.« less