Session: OAC-07-01 Plant Life Extension: Aging & Life Management-1

Paper Number: 153692

153692 - A Methodology for the Management of Stress Corrosion Cracking in Ageing Pressurised Water Reactor Plants 

Abstract: 

As the operating lifetimes of nuclear plants is increasing, effective management of ageing assets is required to ensure continued safety and availability.  Prolonging of plant lifetimes increases exposure to the three fundamental precursors for Stress Corrosion Cracking (SCC); tensile stress, corrosive environment and susceptible material. 

The majority of SCC initiation in civil nuclear plants has occurred in occluded and/or stagnant dead leg regions exposed to oxygenated and/or contaminated conditions.  Although, it has been recognised instances can occur within good quality primary coolant. 

Operating events have demonstrated the influence of historical actions and their impact on the through life management of ageing Pressurised Water Reactor (PWR).  The culmination of sensitised material, maintenance activities introducing oxygenated conditions and residual stresses has led to initiation in regions previously considered to be low risk.

This paper reviews the initiating and growth thresholds of SCC within ageing PWR and the methodology for the management of risk when considering plant life extensions through:

a) Review of plant components against SCC initiators and contributory factors including material susceptibility to sensitisation, manufacturing processes inducing elevated stresses and entrapment of oxygenated conditions during build and through life maintenance activities.

b) Quantification of the level of risk for plant components to identify regions which may have previously been considered negligible.

c) Review of the availability and suitability of current in-service inspection techniques to inform of the level of risk.

d) Considerations of plant management for the mitigation of SCC initiation and growth during periods of deviation from normal operating conditions.

Presenting Author: Matthew Hoyle Rolls-Royce Plc.

Presenting Author Biography: Matthew Hoyle has worked for Rolls-Royce Plc. since 2021 with experience in both the aerospace and defence industries. He currently holds an MEng in Mechanical Engineering, but more recently is working towards an MSc in Nuclear Science and Technology from the University of Manchester. In his current role as a mechanical design engineer, Matthew covers vessels, mounting and pipework components.

Authors:

Matthew Hoyle Rolls-Royce Plc.
James Wilson Rolls-Royce
Timothy Watkins Rolls-Royce