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  • Optimization is implemented in accordance with existing guidance docs.

  • Minor site procedure changes beneficial to support maximum optimization.

  • Optimization uses existing software and databases.

  • PRA input to the Maintenance Rule program is reviewed and adjustments made accordingly

  • Expert panel role for Maintenance Rule activities can then be focused on risk as described in regulations.

  • Line Management can approve Maintenance Rule program decisions (A1, A2, plan approval, monitoring thresholds………..)

Maintenance Rule Program savings for an optimized site typically exceed 2.5 person-years per year, representing a substantial reduction in implementation costs and freeing up site personnel to perform other core business activities.


  • Maintenance Rule programs as currently implemented are man-hour intensive and duplicate efforts of other programs.

  • Maintenance Rule programs classify equipment problems as functional failures when the design function was not lost.

  • Maintenance Rule programs do not implement a graded approach and assign investigations/evaluations to degraded conditions that are not an actual loss of risk significant functions.

  • Consolidate and Align Maintenance Rule function definitions to the design mitigation function and monitor for loss of that function.

    • Many sites have hundreds of functions defined

    • Post consolidation and realignment results in approximately 120 functions (1 to 3 per system)

  • Set thresholds for degraded functionality using Condition Monitoring and evaluate trends when thresholds are exceeded.​

  • Design graded approach so Corrective Action Programs and Work Management are leading programs and Maintenance Rule is a backstop.



  • Unavailability monitoring is over applied throughout the industry.

  • NUMARC discusses using availability monitoring for goal setting A1 if value is provided and where balancing is needed. Gives Emergency Diesel Generators as an example.

  • With Maintenance Rule optimization, unavailability monitoring can be aligned and/or limited to Mitigating System Performance Index requirements.

  •  Action to balance reliability and availability is seldom needed.

    •  Needed if too much Preventative Maintenance is being done.

    • Needed if not enough Preventative Maintenance or inadequate Preventative Maintenance is evident through Functional Failure and Condition Monitoring.

  • Need for Balancing should be a rare event and can be identified with existing indicators during periodic reviews.

  • Balancing is a utility option as stated in NUMARC 93-01.



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