In Auburngrads/SMRD: Statistical Methods For Reliability Data

Example 1.5 - Heat Exchanger Tube Crack Data (Meeker & Escobar, 1996)

• Motivation for the study

  • Nuclear power plants use heat exchangers to transfer energy from the reactor to the steam turbines

  • Heat exchangers can contain thousands of tubes to transfer steam

  • As result of continuous exposure to steam and pressure, the tubes can develop cracks

  • If the cracks grow large enough, a catastrophic failure could occur

  • Tubes are periodically inspected (nondestructive) for cracks

  • If a crack is found that tube is sealed off and no longer used

  • Once a certain number of tubes have been sealed, the entire heat exchanger must be replaced

• Study objectives

  • Engineers what to estimate the service life of the tubes at three nuclear power plants

  • Only a sample of the tubes at each nuclear power plant (100) can be inspected

  • If the from all three plants could be combined a better estimate of the the service life could be found

  • The data can only be combined if the tubes came from a similar manufacturing process and were used under similar conditions

• Data set heatexchanger

  • The data are inspection results from 300 heat exchanger tubes across three geographically separated plants

  • The observations are right, left and interval censored since each plant began operating one year apart

  • Across the 300 tubes inspected, 11 were found to have cracks of sufficient length to be sealed off

Auburngrads/SMRD documentation built on Sept. 14, 2020, 2:21 a.m.