Session: DA-02-02 Design & Analysis of Piping and Components - 2

Paper Number: 108378

108378 - A Methodology for Management of the Risk of Stress Corrosion Cracking of Cold Worked Austenitic Stainless Steels in Good Quality Water in Pressurised Water Reactor Plant 

Although a complex degradation mechanism, the precursors for Stress Corrosion Cracking (SCC) are simply tensile stress, susceptible material and a corrosive environment as expressed by the textbook Venn Diagram.  The vast majority of inservices failures in civil nuclear reactors relating to SCC have typically occurred in sensitised stainless steel components located in occluded and/or stagnant regions.   However, recent operating events have highlighted the risk of Stress Corrosion Cracking SCC of cold worked austenitic stainless steels exposed to good quality primary coolant  This paper explores the thresholds for initiation and growth of SCC in good quality water and outlines a methodology for the management of plant risks through:

a) Review of plant components versus the key risk indicators –fabrication processes that introduce cold work, elevated surface hardness, high operational loads, chemical composition and primary circuit operating temperatures.

b) SCC growth rate calculations for high risk sites to determine if SCC initiation could pose a threat to integrity over the plant lifetime

c) Review of the adequacy of existing in-service inspection regimes for defence in depth monitoring for signs of SCC

d) Deployment of supplementary optimised inspection techniques for high risk sites

e) Factoring of operational experience and examination of decommissioned plant components

 

 

Presenting Author: Joseph Malin Rolls royce

Presenting Author Biography: Rollsroyce design engineer

Authors:

Joseph Malin Rolls royce
James Wilson Rollsroyce
Timothy Watkins Rollsroyce
Timothy Harrison rolls-royce
Benjamin Pellereau rolls-royce