Flaws in Zr-2.5 Nb alloy pressure tubes of CANDU nuclear reactors are susceptible to a crack initiation and growth mechanism called Delayed Hydride Cracking (DHC), which is a repetitive process that involves hydrogen diffusion, hydride precipitation, growth of the hydrided region and fracture of the hydrided region at the flaw-tip. The presence of small surface irregularities, or secondary flaws, at the bottom of service-induced fretting flaws in pressure tubes requires an integrity assessment in terms of DHC initiation. Experimental data and analytical modeling are required to predict whether DHC initiation can occur from the secondary flaws. In the present work, an experimental program was carried out to examine the impact of small secondary flaws with sharp radii on DHC initiation from simulated fretting flaws. Groups of cantilever beam specimens containing blunt notches with and without secondary flaws were prepared from unirradiated pressure tube materials hydrided to a nominal concentration of 50 wt ppm hydrogen. The specimens were subjected to multiple thermal cycles to form hydrides at the flaw-tip at different applied stress levels, which straddled the threshold value for DHC initiation. The threshold conditions for DHC initiation were established for different simulated fretting and secondary flaws. The experimental results are compared with predictions from the engineering process-zone DHC initiation model.
Skip Nav Destination
ASME/JSME 2004 Pressure Vessels and Piping Conference
July 25–29, 2004
San Diego, California, USA
Conference Sponsors:
- Pressure Vessels and Piping Division
ISBN:
0-7918-4669-5
PROCEEDINGS PAPER
Delayed Hydride Cracking Initiation at Simulated Secondary Flaws in Zr-2.5 Nb Pressure Tube Material
Jun Cui,
Jun Cui
Kinectrics, Inc., Toronto, Ontario, Canada
Search for other works by this author on:
Gordon K. Shek,
Gordon K. Shek
Kinectrics, Inc., Toronto, Ontario, Canada
Search for other works by this author on:
Douglas A. Scarth,
Douglas A. Scarth
Kinectrics, Inc., Toronto, Ontario, Canada
Search for other works by this author on:
William K. Lee
William K. Lee
Ontario Power Generation, Pickering, Ontario, Canada
Search for other works by this author on:
Jun Cui
Kinectrics, Inc., Toronto, Ontario, Canada
Gordon K. Shek
Kinectrics, Inc., Toronto, Ontario, Canada
Douglas A. Scarth
Kinectrics, Inc., Toronto, Ontario, Canada
William K. Lee
Ontario Power Generation, Pickering, Ontario, Canada
Paper No:
PVP2004-2301, pp. 53-65; 13 pages
Published Online:
August 12, 2008
Citation
Cui, J, Shek, GK, Scarth, DA, & Lee, WK. "Delayed Hydride Cracking Initiation at Simulated Secondary Flaws in Zr-2.5 Nb Pressure Tube Material." Proceedings of the ASME/JSME 2004 Pressure Vessels and Piping Conference. Fracture Methodologies and Manufacturing Processes. San Diego, California, USA. July 25–29, 2004. pp. 53-65. ASME. https://doi.org/10.1115/PVP2004-2301
Download citation file:
15
Views
Related Proceedings Papers
Related Articles
Delayed Hydride Cracking Initiation at Notches in Zr-2.5Nb Alloys
J. Pressure Vessel Technol (August,2009)
Initiation and Arrest of Delayed Hydride Cracking in Zr–2.5Nb Tubes
J. Pressure Vessel Technol (February,2009)
Overload Fracture of Hydrided Region at Simulated Blunt Flaws in Zr-2.5Nb Pressure Tube Material
J. Pressure Vessel Technol (August,2009)
Related Chapters
Radial Delayed Hydride Cracking in Irradiated Zircaloy-2 Cladding: Advanced Characterization Techniques
Zirconium in the Nuclear Industry: 20th International Symposium
Mechanical Behavior of Zircaloy-4 in the Presence of Hydrogen in Solid Solution at Elevated Temperatures
Zirconium in the Nuclear Industry: 20th International Symposium
On Interfacial Ribbons of ζ- and γ-Hydride Phases Surrounding δ Precipitates in Zircaloy-2
Zirconium in the Nuclear Industry: 20th International Symposium