Positron Lifetime Characterization of Irradiated Pressure Vessel Model Alloys

2008 ◽  
pp. 257-257-5
Author(s):  
M Valo ◽  
H Huomo ◽  
P Nyberg ◽  
P Hautojarvi
Keyword(s):  
Pressure Vessel ◽  
Positron Lifetime

scholarly journals Use of Mini-CT Specimens for Fracture Toughness Characterization of Low Upper-Shelf Linde 80 Weld Before and After Irradiation

2018 ◽  
Author(s):  
Mikhail A. Sokolov
Keyword(s):  
Fracture Toughness ◽  
Pressure Vessel ◽  
Master Curve ◽  
Collaborative Program ◽  
Before And After ◽  
Minimum Number ◽  
Real Practice ◽  
Reactor Pressure ◽  
Good Agreement

Mini-CT specimens are becoming a highly popular geometry for use in reactor pressure vessel (RPV) community for direct measurement of fracture toughness in the transition region using the Master Curve methodology. In the present study, Mini-CT specimens were machined from previously tested Charpy specimens of the Midland low upper-shelf Linde 80 weld in both, unirradiated and irradiated conditions. The irradiated specimens have been characterized as part of a joint ORNL-EPRI-CRIEPI collaborative program. The Linde 80 weld was selected because it has been extensively characterized in the irradiated condition by conventional specimens, and because of the need to validate application of Mini-CT specimens for low upper-shelf materials — a more likely case for some irradiated materials of older generation RPVs. It is shown that the fracture toughness reference temperatures, To, derived from these Mini-CT specimens are in good agreement with To values previously recorded for this material in the unirradiated and irradiated conditions. However, this study indicates that in real practice it is highly advisable to use a much larger number of specimens than the minimum number prescribed in ASTM E1921.

Characterization of free volumes in amorphous and nanostructured Pr2Fe14B using positron lifetime spectroscopy

2003 ◽  
Vol 198 (1) ◽  
pp. 204-209
Author(s):  
Y. C. Wu ◽  
F. Ye ◽  
V. Barbe ◽  
W. Sprengel ◽  
K. Reimann ◽  
...  
Keyword(s):  
Positron Lifetime ◽  
Positron Lifetime Spectroscopy

Radiological Characterization of the Pressure Vessel Internals of the BNL High Flux Beam Reactor

2004 ◽  
Vol 87 ◽  
pp. S25-S30 ◽  
Author(s):  
Norman E. Holden ◽  
Richard N. Reciniello ◽  
Jih-Perng Hu
Keyword(s):  
Pressure Vessel ◽  
High Flux ◽  
Radiological Characterization

Microstructure Development and Precipitation Effects in Ultra Fine Grained Mg-3Tb-2Nd Alloy Prepared by High Pressure Torsion

2008 ◽  
Vol 584-586 ◽  
pp. 591-596 ◽  
Author(s):  
Jakub Čížek ◽  
Ivan Procházka ◽  
Bohumil Smola ◽  
Ivana Stulíková ◽  
Martin Vlach ◽  
...  
Keyword(s):  
High Pressure ◽  
Positron Lifetime ◽  
High Pressure Torsion ◽  
Creep Properties ◽  
Fine Grained ◽  
Transmission Electron ◽  
Highly Sensitive ◽  
Ideal Tool ◽  
Increasing Temperature

Mg-Tb-Nd ternary alloy represents a novel hardenable Mg-based alloy with enhanced strength and favorable creep properties. In the present work we studied microstructure of ultra fine grained (UFG) Mg-Tb-Nd alloy prepared by high pressure torsion (HPT). Lattice defects introduced into the specimen by the severe plastic deformation play a key role in physical properties of UFG specimens. It is known that positron lifetime (PL) spectroscopy is highly sensitive to open volume defects (like vacancies, dislocations, etc.). Therefore, PL spectroscopy is an ideal tool for defect characterizations in the HPT deformed specimens. In the present work we combined PL studies with transmission electron microscopy and microhardness measurements. After detailed characterization of the as-deformed structure, the specimens were step-by-step isochronally annealed and we investigated the development of microstructure with increasing temperature.

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