3.6.1. Operating experience feedback

Sharing of experience and learning from operating experience (including errors), from R&D programmes and the assessment of performance trends should be used as input to an effective PLiM programme. However, relying solely on a “learning by mistake” strategy is not advisable, because it involves reliance on “unanticipated ageing” and unanticipated ageing is costly. It generally requires more extensive equipment refurbishment and costs replacement power, if it causes a forced maintenance shutdown. Examples of unanticipated ageing are:

• EWS spray header erosion in CANDU 6

• Feeder thinning rates and higher flow assisted corrosion of carbon steel

• Pressure tube Spacer shifting and repositioning

• Pressure tube creep rates higher than anticipated.

• Steam generator (higher than anticipated deposition rates, divider plate accelerated leakage rate)

If unanticipated ageing (learn by mistake attitude) remains unchecked, it has the potential to also adversely affect safety, due to undetected changes in equipment condition and it tends to produce “institutional or safety culture degradation” as well.