Design and Analysis

Determination of CANDU End Fitting Jacking Limits Using Elastic–Plastic Finite Element Analysis1

[+] Author and Article Information
Bing Li

Mech & Civil Engineering,
AMEC NSS Limited,
700 University Ave, 2nd floor,
Toronto, Ontario, Canada M5G 1X6
e-mail: bing.li@amec.com

David McNeish

Major Reactor Components,
Bruce Power,
177 Tie Road,
Tiverton, Ontario, Canada N0G 2T0
e-mail: david.mcneish@brucepower.com

Seyun Eom

Assessment and Analysis,
Canadian Nuclear Safety Commission,
280 Slater Street,
Ottawa, Ontario, Canada K1P 5S9
e-mail: seyun.eom@cnsc-ccsn.gc.ca

Dk Vijay

e-mail: dk.vijay@amec.com

Si-tsai Lin

e-mail: si-tsai.lin@amec.com

Jian Li

e-mail: jian.li@amec.com
Major Component Engineering,
AMEC NSS Limited,
393 University Ave, 4th floor,
Toronto, Ontario, Canada M5G 1E6

This paper should be considered research, not constituting official regulatory position, which has to be in the form of formal letter from the CNSC.

Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received February 24, 2011; final manuscript received February 14, 2012; published online November 8, 2012. Assoc. Editor: Maher Y. A. Younan.

J. Pressure Vessel Technol 134(6), 061208 (Nov 08, 2012) (5 pages) doi:10.1115/1.4006120 History: Received February 24, 2011; Revised February 14, 2012

In one CANDU reactor unit in Ontario, the west end fitting is designed to connect to the end shield via a stop collar. The outboard end of the stop collar is welded to an attachment ring, which shrink-fits on the end fitting body. The east side end fitting is supported by inboard and outboard journal rings resting on their respective bearing sleeves, which allow the “free” axial movement of the channel. In support of some maintenance activities, the west end fitting is required to be jacked to get certain clearance for accommodating the operating tools. The previous elastic calculation got the jacking limit of 8.89 mm, which did not provide enough clearance for tooling. In this paper, an elastic–plastic finite element analysis following ASME B&PV code Section III, Division 1, Subsection NB is performed to increase the jacking limit. The finite element analysis is carried out using ANSYS and validated by an ABAQUS model. In the elastic–plastic finite element analysis, the following effects are considered: strain hardening of stop collar material, stress concentration in stop collar weld, notch effect on stress concentration, and fatigue in stop collar. Cyclic jacking loads as displacement controlled loading are applied in the analysis. Considering the time to the end of unit life, the maximum anticipated end fitting jacking cycles are eight. The higher jacking limit is achieved with an acceptable plastic deformation and fatigue damage at the stop collar, which is the weakest part during the end fitting jacking. The results show that the end fitting can be jacked at west side end-face with 29.7 mm for 1–3 cycles, 29.2 mm for 4 cycles, 26.2 mm for 5 cycles, 24.1 mm for 6 cycles, 21.6 mm for 7 cycles, and 20.3 mm for 8 cycles. The jacking limits achieved in this paper provide enough clearance for the required maintenance operations.

Copyright © 2012 by ASME
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ASME Boiler and Pressure Vessel Code, 2007, Section III, Division 1, Subsection NB, ASME, New York.
ANSYS Release 10.0, ANSYS, Inc., Canonsburg, PA.
ASME Code for Pressure Piping, 2007, Power Piping B31.1, ASME, New York.
ASME Boiler and Pressure Vessel Code, 2007, Section II, Part D—Material Properties, ASME, New York.
ABAQUS Version 6.7, Dassault Systems SIMULIA, Providence, RI.
Neuber, H., 1961, “Theory of Stress Concentration for Shear-Strained Prismatical Bodies With Arbitrary Nonlinear Stress-Strain Law,” J. Appl. Mech., 28, pp. 544–550. [CrossRef]
Pilkey, W. D., and Pilkey, D. F., 2008, Peterson’s Stress Concentration Factors, Wiley, New York.
Peterson, R. E., 1953, Stress Concentration Design Factors, Wiley, New York.
ASME Boiler and Pressure Vessel Code Case, 2003, N-597-2, ASME, New York.
ASME Boiler and Pressure Vessel Code, 2007, Section III, Division 1, Appendix I, ASME, New York.


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Fig. 2

West end fitting jacking model

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Fig. 1

Schematic view of a CANDU fuel channel

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Fig. 3

Stress–strain curve applied in FE model for the stop collar material

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Fig. 4

Maximum principal strain at stop collar—ANSYS

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Fig. 5

Maximum principal strain at stop collar—ABAQUS

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Fig. 6

ANSYS plot of principal strain with deformed shape of end fitting (scale factor of 12 applied)

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Fig. 7

Schematic view of the stop collar

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Fig. 8

Cyclic stress–strain curve for the stop collar



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