Proactive Pressure Relief System Management of Life Cycle and Ageing in Nuclear Power Plants
9th International Conference on CANDU® Maintenance - 2011 December 04-06

Presented at:
9th International Conference on CANDU® Maintenance
2011 December 04-06
Toronto, Canada
Session Title:
Getting it Right Session B2

Josh Kolenc (Farris Engineering)
Steve Ferrar (Farris Engineering)
Sean Croxford (Farris Engineering)
Steve Saunders (Farris Engineering)


1.1 Introduction

As the world’s aging nuclear plants continue to be challenged with maintenance and replacement issues (obsolescence) as well making improvements within their systems, proper pressure relief system management looms as a growing concern. This problem grows more acute as new engineering best practices are promulgated across industries and regulatory standards and regulations become more rigorous and much more strictly enforced.

Unlike most pieces of operating equipment in a nuclear facility, pressure relief systems and pressure relief devices demand an extra level of consideration; as they form the “last line of defense” to prevent potential catastrophic events. Combine the on-going obsolescence issue with today’s ever increasing demands for overall plant and public safety; pressure relief safety management will require a much more “proactive” effort.

1.1.1 Basic Management Issues - for pressure relief systems involve:

  • Understanding the ageing and obsolescence phenomena along with changes/upgrades within pressure relief systems and identifying the (potential) effects on pressure relief devices and their associated equipment
  • Advanced technological tools to seamlessly integrate plant PRV maintenance and plant PRV engineering
  • Advance technological tools to address 2phase flow modeling in pressure relief system hydraulic systems
  • Using newer technologies to address overpressure scenario oversights on existing systems
  • Addressing the specific impact of these effects on the plant taking into account the operational profiles and analyzing the risks
  • Carrying out the necessary mitigating actions to counteract the effects of the ageing and obsolescence.
  • Having a robust, reliable and actionable Management of Change system Proactive Management Requirements - for ageing and obsolescence processes requires the following:

Maintainable relief system design documentation for the life of a relief system designed in accordance with relevant codes and standards

Supports PHA’s and audits

Facilitates Management of Change

Provides a record of the current relief system

Documentation of user supplied relief system design guidance

Documentation of references used in a relief system study (relief system load calculations

Protected Equipment (P&ID’s, PFD’s etc.)

List of Overpressure scenarios

Pressure relief device documentation

Installation documentation (Piping ISO’s, inlet/outlet pressure drop calculations) Solution

Today’s high end software solutions, combined with new innovative maintenance and engineering capabilities can easily address the proactive management of relief systems safety compliance according to best-practices principles, including:

  • the management of compliance-related as-operating data
  • the ongoing verification of standards-based compliance

and produces:

  • tasks for plant management
  • reports for regulatory purposes
  • easily accessible compilation of overpressure protection systems data and basis

The net results are:

  • safer plants

major cost savings due to the elimination of duplication of effort in plant data recording and tracking.

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