The basis for determining the size of the random sample of tubes to be inspected in replacement steam generators is revisited in this paper. A procedure to estimate the maximum number of defective tubes left in the steam generator after no defective tubes have been detected in the randomly selected inspection sample is proposed. A Bayesian estimation is used to obtain closed-form solutions for uniform, triangular, and binomial prior densities describing the number of failed tubes in steam generators. It is shown that the particular way of selecting the random inspection sample (e.g., one sample from both SG, one sample from each SG, etc.) does not affect the results of the inspection and also the information obtained about the state of the uninspected tubing, as long as the inspected steam generators belong to the same population. Numerical examples further demonstrate two possible states of the knowledge existing before the inspection of the tubing. First, virtually no knowledge about the state of the steam generator tubing before the inspection is modeled using uniform and triangular prior densities. It is shown that the knowledge about the uninspected part of the tubing strongly depends on the size of the sample inspected. Further, even small inspection samples may significantly improve our knowledge about the uninspected part. On the other hand, rather strong belief on the state of the tubing prior to the inspection is modeled using binomial prior density. In this case, the knowledge about the uninspected part of the tubing is virtually independent on the size of the sample. Furthermore, it is shown qualitatively and quantitatively that such inspection brings no additional knowledge on the uninspected part of the tubing.
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February 2007
Research Papers
Reliability of Sampling Inspection Schemes Applied to Replacement Steam Generators
Guy Roussel,
e-mail: gr@avn.be
Guy Roussel
Association Vinçotte Nuclear
, Rue Walcourt 148 Walcourtstraat, B-1070 Brussels, Belgium
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Leon Cizelj
Leon Cizelj
Search for other works by this author on:
Guy Roussel
Association Vinçotte Nuclear
, Rue Walcourt 148 Walcourtstraat, B-1070 Brussels, Belgiume-mail: gr@avn.be
Leon Cizelj
J. Pressure Vessel Technol. Feb 2007, 129(1): 109-117 (9 pages)
Published Online: March 21, 2006
Article history
Received:
July 14, 2005
Revised:
March 21, 2006
Citation
Roussel, G., and Cizelj, L. (March 21, 2006). "Reliability of Sampling Inspection Schemes Applied to Replacement Steam Generators." ASME. J. Pressure Vessel Technol. February 2007; 129(1): 109–117. https://doi.org/10.1115/1.2389027
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