3.8.1. Overview of integrated safety performance assessments

To properly set up a PLiM driven action plan, compounded effects of interfacing ageing components and systems must be considered. For example PT creep must be considered in concert with the other PHTS ageing mechanisms and effects such as boiler fouling, increased resistance in the boilers, effects on reactor overpower (ROP) and bundle power and channel power limits, evolution of the inlet feeder temperature, heat transport system asymmetries, effects on Steam Generator pressure and on critical channel power limits. A corrective maintenance plan should be devised in view of the overall objectives. For example PLiM results may suggest boiler divider plate change out, steam generator cleaning, ultrasonic flow measurement (USFM) both cold & on line, trip calibration, use of high performance fuel to restore original design margins, but all these suggestions must be vetted in the context of overall performance, safety parameters and operating margins, etc.

Stations may be required to incorporate effect into ROP set point and perform detailed assessment for ROP, time to contact studies, studies to determine the effect on Reactor control, on bundle power and channel power (BP/CP) affecting uncertainties & limits, shutdown system effectiveness for LOCA and in-core breaks.