Abstract
Threshold conditions for DHC initiation at volumetric flaws—which require a different treatment than is appropriate for DHC initiation at cracks—is summarized in this chapter. The initial approach, based on a peak stress threshold criterion, resulted in this threshold decreasing with the number of reactor shutdown cycles. This was found to be too restrictive on reactor operation. Moreover, the method did not have an explicit dependence on flaw geometry (root radius) nor could it readily be used to assess the DHC initiation potential of sharp secondary flaws at the root of blunt flaws. The hydride process zone model that was developed to eliminate these deficiencies of the peak threshold stress model is described in this chapter. Details of the validation procedures of the engineering process zone model in relation to the experimental data base for DHC initiation from blunt flaws in unirradiated and pre-irradiated Zr–2.5Nb pressure tube material are given.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsNotes
- 1.
This expression was not actually given in the original derivation but follows from standard fracture mechanics theory for a strip-yield model.
- 2.
The notation for the hydrided region’s stress and relative displacement at the flaw tip (\( p_{ * } \) and \( v_{ * } \), respectively) used in Smith’s paper is different from what is used here. The notation has been changed to be consistent with Smith’s later notation for these parameters.
- 3.
These two values are presently considered as the nominal lower bound values for \( K_{IH} \) and \( p_{c} \) for use in assessment methodologies.
References
Anon: Technical Basis for the Fitness-for-service Guidelines for Zirconium Alloy Pressure Tubes in Operating CANDU Reactors. Internal report of CANDU Owners Group (COG) COG Report No. COG-96–651, Revision 0 (1996)
Bilby, B.A., Cottrell, A.H., Swinden, K.H.: The spread of plastic yield from a notch. Proc. Roy. Soc. London A 272, 304–314 (1963)
CSA: Technical Requirements for the In-service Evaluation of Zirconium Alloy Pressure Tubes in CANDU Reactors. Canadian Standards Association, Mississauga, Ontario, Canada, Nuclear Standard N285.8–10 (2010)
Cui, J., Scarth, D.A., Shek, D.K., et al.: Delayed hydride cracking initiation at simulated secondary flaws in Zr–2.5 Nb pressure tube material. Int. J. Pres. Ves. Piping 474, 53–65 (2004)
Dugdale, D.S.: Yielding of steel sheets containing slits. J. Mech. Phys. Solids 8, 100–104 (1960)
Eadie, R.L., Metzger, D.R., Léger, M.: The thermal ratcheting of hydrogen in zirconium-niobium: An illustration using finite element modeling. Scripta Metall. 29, 335–340 (1993)
Eshelby, J.D.: The determination of the elastic field of an ellipsoidal inclusion, and related problems. Proc. Roy. Soc. London A 241, 376–396 (1957)
Eshelby, J.D.: Elastic inclusions and inhomogeneities. Prog. Sol. Mech. 2, 89–140 (1961)
Sagat, S., Shi, S.Q., Puls, M.P.: Crack initiation criterion at notches in Zr–2.5Nb alloys. Mater. Sci. Eng. A176, 237–247 (1994)
Scarth, D.A.: A new procedure for evaluating flaws in CANDU nuclear reactor pressure tubes for the initiation of delayed hydride cracking. PhD Thesis, University of Manchester, Manchester (2002)
Scarth, D.A.: Unpublished. Kinectrics Inc., Toronto, Ontario, Canada (2004)
Scarth, D.A., Smith, E.: Developments in flaw evaluation for CANDU reactor Zr–Nb pressure tubes. Int. J. Pres. Ves. Piping 123, 41–48 (2001)
Scarth, D.A., Smith, E.: The use of failure assessment diagrams to describe DHC initiation at a blunt flaw. Int. J. Pres. Ves. Piping 412, 63–73 (2002)
Scarth, D.A., Smith, E.: The effect of plasticity on process zone predictions of DHC initiation at a flaw in CANDU reactor Zr–Nb pressure tubes. Int. J. Pres. Ves. Piping 437, 19–30 (2003)
Shi, S.Q., Puls, M.P.: Criteria for fracture initiation at hydrides in zirconium alloys II. Shallow notch. J. Nucl. Mater 208, 243–250 (1994)
Shi, S.Q., Puls, M.P.: Criteria for fracture initiation at hydrides in zirconium alloys I. Sharp crack tip. J. Nucl. Mater. 208, 232–242 (1994)
Smith, E.: The initiation of delayed hydride cracking at a blunt flaw. Int. J. Pres. Ves. Piping 62, 9–17 (1995)
Smith, E.: The fracture of hydrided material during delayed hydride cracking (DHC) crack growth. Int. J. Pres. Ves. Piping 61, 1–7 (1995)
Smith, E.: Near threshold delayed hydride crack growth in zirconium alloys. J. Mater. Sci. 30, 5910–5914 (1995)
Smith, E.: Threshold stress criterion for delayed hydride crack initiation at a blunt notch in zirconium alloys. Int. J. Pres. Ves. Piping 68, 53–61 (1996)
Smith, E: Unpublished. Kinectrics Inc., Toronto, Ontario, Canada (1996–2006)
Simpson, L.A., Cann, C.D.: Fracture toughness of zirconium hydride and its influence on the crack resistance of zirconium alloys. J. Nucl. Mater. 87, 303–316 (1979)
Xu, S., Scarth, D.A.: Unpublished. Kinectrics Inc., Toronto, Ontario, Canada (2009)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Copyright information
© 2012 Springer-Verlag London
About this chapter
Cite this chapter
Puls, M.P. (2012). DHC Initiation at Volumetric Flaws. In: The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components. Engineering Materials. Springer, London. https://doi.org/10.1007/978-1-4471-4195-2_11
Download citation
DOI: https://doi.org/10.1007/978-1-4471-4195-2_11
Published:
Publisher Name: Springer, London
Print ISBN: 978-1-4471-4194-5
Online ISBN: 978-1-4471-4195-2
eBook Packages: EngineeringEngineering (R0)