1 / 19

M. Hasegawa 1 ） , Y. Nagai 1) , T. Toyama 1) , Zheng Tang 1) , Y. Nishiyama 2) , M. Suzuki 2) ,

International Workshop on “Influence of atomic displacement rate, neutron spectrum and irradiation temperature on radiation-induced ageing of power reactor components”, October 4, 2005, Ulyanovsk, Russia. Effects of irradiation flux on embrittlement mechanisms

dalila
Download Presentation

M. Hasegawa 1 ） , Y. Nagai 1) , T. Toyama 1) , Zheng Tang 1) , Y. Nishiyama 2) , M. Suzuki 2) ,

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. International Workshop on“Influence of atomic displacement rate, neutron spectrum and irradiation temperature on radiation-induced ageing of power reactor components”, October 4, 2005, Ulyanovsk, Russia Effects of irradiation flux on embrittlement mechanisms on reactor pressure vessel steel: Cu nano-precipitates and defects studied by positron annihilation and 3 dimensional atom probe M. Hasegawa1）, Y. Nagai1), T. Toyama1), Zheng Tang1), Y. Nishiyama2), M. Suzuki2), T. Ohkubo4) and K. Hono4) 1) Tohoku University, Japan hasegawa@imr.tohoku.ac.jp 2) Japan Atomic Energy Research Institute (JAERI), Japan 3) National Institute for Materials Science (NIMS), Japan

  2. Outline RPV Surveillance Test Specimens 1) Introd. to Positron Annihilation (PA*)) 2) Flux Eeffcts Calder Hall Reactor vs JMTR (PA & 3D-AP**)) * ) Positron Annihilation (PA) **) 3Dimensional Atom Probe (3D-AP)

  3. 0 1.27 MeV 22Na Cu Fe e+ (a) (b) 0.511 MeV 1 (c) 0.511 MeV 2 (d) (a) Injection and thermalization, (b) Diffusion, (c) Trapping, (d) Annihilation. e+ annihilates with a Cu electron

  4. 22Na e+: Self-Searching Probe Cu Nanovoid Cu-V Complex Cu Nano-Precipitates Positron Quantum Dot State Positron Density 2 1

  5. Embedded Particles - Cu Precipitates in Dilute Fe-Cu Alloys - Positron Density Distributions Cu1 Cu5 Cu59 Diameter ~ 1 nm Fe Cu Super-Cell:1024 atom sites

  6. Positron Quantum-Dot Confinement in a Precipitate of 59 Cu Atoms Embedded in Fe Matrix Fe Cu Density isosurface ofa quantum-dot confined positron in a Cu59 in Fe matrix. The isodensity value is 0.5% of the maximum.

  7. Coincidence Doppler Broadening : CDB pL : Electron Momentum along the Emitted γ–ray γ1 γ2 e- e+ Ge detector Ge detector CDB CDB Ratio Spectra Cu 3d10 Electrons Normalize to Pure Fe Low High Low High Low Momentum Region :Vacancy type defects High Momentum Region: Cu Nano-Precipitates

  8. Fe-0.3wt%Cu: CDB Ratio Curves neutron-irrad.: 8.3×1018n/cm2, 100C Normalized toFe Normalized toCu Pure Cu Vac. Type Defects Vac. Type Defects Cu 3d Peak Pure Fe As-Irrad. Almost Flat As-Irrad. No Fe Valley τ1 = 165ps : ~ monovacancies(V1) τ2 = 405ps (51%) nanovoids (~V30) Vacancy & nanovoid covered with Cu atoms

  9. V2 [100] V2 [111] V9 V5 V15 Positron Lifetimeand Binding Energy in Vacancy Clusters in Fe Positron Binding Energy Positron Lifetime

  10. Embrittlement Mechanisms: Fluence Evolution Total Embrittlement Matrix Defects Cu Nano Precipitates Soneda (2003) Neutron Flux Effects on the Embrittlement Mechanisms ? 108 109 1010 1013 1014 1011 1012 Neutron Flux (n/cm2/s) Calder Hall-Type Reactor MTR BWR·PWR

  11. Calder Hall Reactor (CHR) in Tokai*, Japan: Surveillance Test Specimen C-Mn base Ferritic Steel wt.% *In –Service (1966 – 1998) Post-Weld Heat Treatment : 600ºC, 4h. Irradiation Conditions High flux Low flux *Japan Materials Testing Reactor

  12. Strengthening by Irradiation CHR vs. JMTR Irradiated at 240ºC JMTR 3.6x1012n/cm2·s CHR Surveillance 4.2x108n/cm2·s

  13. CDB (Low, High) Momentum Correlation Positron Lifetime I2 Pure Cu CHR Surveillance Thermal Ageing: Cu Nano Precipitates V1 τ2 V1 τav aged at 300ºC, 70,000h Pure Fe bulk Fe aged at 400ºC, 70,000h Unirrad. JMTR τ1 Vacancy-Type Defects Pure Fe irrad. 300ºC, 70,000h JMTR CHR Surveillance 400ºC, 70,000h Unirrad.

  14. 3D-AP Mapping : As-irrad. JMTR CHR Surveillance 10nm 10nm Cu 10nm 10nm 30nm 30nm Mn Ni Si

  15. CHR Surveillance CHR Surveillance JMTR JMTR Isochronal Annealing: CDB & Hardness 200~700ºC, 30 min. CDB Low/High Momentum Correlation Vickers Microhardness Recovery of Vacancy-Type Defects Recovery of Cu Nano- Precipitates Pure Fe（As-irrad.）

  16. CHR Surveillance JMTR Cu 10nm 10nm 10nm 10nm 30nm 30nm Mn Ni Si 3D-AP Mapping : Annealed at 450ºC for 0.5h

  17. Summary : CHR vs. JMTR CHR-Surveillance : Low Flux JMTR : High Flux Positron Annihilation and 3D-AP Analysis for RPV Steels As-irradiated State CHR-Surveillance : Cu nano-precipitates JMTR : Almost no Cu precipitates but vacancy-type defects Post-Irradiation Annealing CHR-Surveillance : The Cu nano-precipitates anneal out andHv recovers at 650ºC. JMTR : The vacancy-type defects recover at 450ºC. The Cu precipitation is not significant. • Marked Flux Effects • Low flux irradiation in CHR : • Strengthning is caused by enhanced Cu precipitation • at very low doses. • High flux irradiation in JMTR : • Almost the same strengthening is due to matrix defects • but not to Cu precipitates.

  18. LEAPin Hasegawa Lab. (Oarai Center) （Local Electrode Atom Probe: LEAPBy IMAGO） Position Sensitive Detector Local Electrode Specimen High Field Region

  19. Cu Precipitates: Fe-1.0wt%Cu Aged at 475C for 10h Conventional Atom Probe (Energy-Compensating Type) LEAP Atom Probe 2x107 Atoms, 1hour 3x105 Atoms, 6 hours 10x10x60 nm 60x60x170 nm

More Related