Research Papers: Materials and Fabrication

An Approach for a Statistical Evaluation of Uncertainty in Assessing Fatigue Usage Including Environmental Effects

[+] Author and Article Information
Yogendra S. Garud

San Jose, CA 95124
e-mail: yogen@garud.com

David A. Steininger

Electric Power Research Institute,
Palo Alto, CA 94303
e-mail: dsteinin@epri.com

Ken Wolfe

Electric Power Research Institute,
Palo Alto, CA 94303
e-mail: kwolfe@epri.com

1Corresponding author.

Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received August 2, 2014; final manuscript received October 19, 2014; published online February 27, 2015. Assoc. Editor: Marina Ruggles-Wrenn.

J. Pressure Vessel Technol 137(5), 051403 (Oct 01, 2015) (7 pages) Paper No: PVT-14-1123; doi: 10.1115/1.4028894 History: Received August 02, 2014; Revised October 19, 2014; Online February 27, 2015

The assessment for adequacy in managing the effects of fatigue in the ASME Code Class-1 (pressure boundary) components is based on a calculated measure of the projected fatigue damage. This measure is the highest cumulative usage factor (CUF) in a given component under a specified set of cyclic loadings and their expected number of repetitions. The Code based calculation of CUF and its adjustments for potential environmentally assisted fatigue (EAF) damage accumulation utilize a multitude of inputs, and conservative assumptions and applied margins. To support the extended service life beyond the original design, or longer life of new designs, changes in inputs and/or conservative assumptions used in these deterministically calculated CUFs are often made to meet a deterministic performance criterion. This makes the impact of uncertainty in the inputs and/or changes in the conservative adjustments difficult to assess. This paper presents a generic, engineering approach for estimation of the uncertainty distribution of CUF based on the expected statistical characteristics of input variables used in the calculation of EAF-based CUF. The approach does not involve Monte Carlo sampling. The proposed statistical approach analytically combines variances of the inputs leading to an acceptable estimation of the total variance of the CUF. The approach does not require specification of full probability distribution(s) for the input variables, nor is the dependence between variables a critical issue from the analytical point of view. Feasibility and limitations of the approach are discussed in relation to the NB-3200 and NB-3600 procedures of the ASME Code and the current Fen-based augmentation for environmental effects. This approach is further examined in the framework of stress–strength interference methodology to account for the uncertainty in the fatigue performance criterion which can lead to a rational deterministic safety factor interpretation and its relation to a quantifiable measure of the probability of exceeding the fatigue performance criterion.

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ASME, 2010, “ASME Boiler and Pressure Vessel Code, Section III, Division 1—Subsection NB, Class 1 Components, 2010 Edition,” The American Society of Mechanical Engineers, NY.
Chopra, O. K., and Shack, W. J., 2007, “Effect of LWR Coolant Environments on the Fatigue Life of Reactor Materials,” U.S. Nuclear Regulatory Commission, Washington, DC, Report No. NUREG/CR-6909 and ANL-06/08.
USNRC, 2007, “Guidelines for Evaluating Fatigue Analyses Incorporating the Life Reduction of Metal Components due to the Effects of the Light-Water Reactor Environment for New Reactors,” U.S. Nuclear Regulatory Commission, Washington, DC, US NRC Reg. Guide 1.207.
EPRI, 2014, “Generic Evaluation of Environmentally Assisted Fatigue in BWR and PWR Reactors: A Feasibility Study,” EPRI, Palo Alto, CA, No. 2014.3002003922.
Chopra, O. K., Garud, Y. S., and Stevens, G. L., 2012, “Update of NUREG/CR-6909 Methodology for Environmentally Assisted Fatigue (EAF)—Revised Fen Expressions,” ASME Code Meetings, Section III Subgroup on Fatigue Strength, Nashville, TN, May 15. [Also, presentation by Stevens, G. L., Chopra, O. K., Garud, Y. S., and Midmore, L., International Boiling Water Reactor and Pressurized Water Reactor Materials Reliability Conference and Exhibit Show 2012, National Harbor, MD, July 19.]
Davis, J. M., and Stevens, G. L., 2007, “Evaluation of Controlling Transient Ramp Times Using Piping Methodologies When Considering Environmental Fatigue (Fen) Effects,” ASME Paper No. PVP2007-26210. [CrossRef]
Ware, A. G., Morton, D. K., and Nitzel, M. E., 1995, “Application of NUREG/CR-5999 Interim Fatigue Curves to Selected Nuclear Power Plant,” U.S. Nuclear Regulatory Commission, Washington, DC, Report No. NUREG/CR-6260.
Hahn, G. J., and Shapiro, S. S., 1967, Statistical Models in Engineering, Wiley, NY.
Vesely, W. E., 1991, “Incorporating Aging Effects into Probabilistic Risk Analysis Using a Taylor Expansion Approach,” Reliab. Eng. Syst. Saf., 32(3), pp. 315–337. [CrossRef]
Santos Filho, J. C. S., Yacoub, M. D., and Cardieri, P., 2006, “Highly Accurate Range-Adaptive Lognormal Approximation to Lognormal Sum Distributions,” Electron. Lett., 42(6), pp. 361–363. [CrossRef]
ASME, 1969, “Criteria of the ASME Boiler and Pressure Vessel Code for Design by Analysis in Sections III and VIII, Division 2,” The American Society of Mechanical Engineers, NY.
Miner, M. A., 1945, “Cumulative Damage in Fatigue,” ASME J. Appl. Mech., 67, pp. A-159–A-164.
Lipson, C., and Sheth, N. J., 1973, Statistical Design and Analysis of Engineering Experiments, McGraw-Hill, NY.
American Institute of Steel Construction, 1986, “Load and Resistance Factor Design Specification for Structural Steel Building,” AISC Publications, Chicago, IL.
Griesbach, T. J., Riccardella, P. C., and Gosselin, S. R., 1991, “Application of Fatigue Monitoring to the Evaluation of Pressurizer Surge Lines,” Nucl. Eng. Des., 129(2), pp.163–176. [CrossRef]
Rudolph, J., Bergholz, S., and Wirtz, N., 2009, “AREVA's Fatigue Concept (AFC)—An Integrated and Multidisciplinary Approach to the Fatigue Assessment of NPP Components,” 20th International Conference on Structural Mechanics in Reactor Technology, Espoo, Finland, SMiRT 20—Division III, Paper 1962.
Monette, P., Joly, P., Roux, V., and Thiry, J-M., 2009, “Longevity Curves for Probabilistic Lifetime Assessment,” 20th International Conference on Structural Mechanics in Reactor Technology, Espoo, Finland, SMiRT 20—Division 7, Paper 1684.
Khaleel, M. A., and Simonen, F. A., 2009, “Evaluations of Structural Failure Probabilities and Candidate Inservice Inspection Programs,” U.S. Nuclear Regulatory Commission, Washington, DC, Report No. NUREG/CR-6986.
Rudland, D., and Harrington, C., 2012, “xLPR Pilot Study Report,” U.S. Nuclear Regulatory Commission, Washington, DC, Report No. NUREG-2110.


Grahic Jump Location
Fig. 1

Comparison of the impact of service loading assumptions on the probability distribution of CUF taking into account various sources of uncertainty affecting the calculated CUF



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