Development of Probabilistic Fracture Mechanics Analysis Code for Pipes with Stress Corrosion Cracks

Abstract

Risk-Informed integrity management methodologies have been developed for Japanese nuclear power plants. One of the issues of concern is the reliability assessment of piping with flaws due to stress corrosion cracking (SCC). Therefore, the probabilistic fracture mechanics analysis code has been developed, which can perform the reliability assessment for austenitic stainless steel piping with flaws due to SCC. This paper describes technical basis of this code. This method is based on Monte-Carlo technique considering many sample cases in a piping section, where the initiation and growth of cracks are calculated and piping failures, including leaks and rapture, are evaluated. A notable feature is that multiple cracks can be treated, consequently, assessment of coalescence of cracks and intricate break evaluation of piping section have been included. Moreover, the in-service inspection (ISI) and integrity evaluation by Fitness-for-Service (FFS) code are integrated into the analysis, and the contribution to failure probability decrease can be assessed. Key parameters are determined on a probability basis with the designated probability type throughout the procedure. Size, location and time of crack initiation, coefficients of crack growth due to SCC and factors for piping failure are included in those parameters. With this method the reliability level of the piping through the operation periods can be estimated and the contribution of various parameters including ISI can be quantitatively evaluated.

Influence of Non-Destructive Examination Performance on Reliability of Pipes Having Stress Corrosion Cracks

“…© 2011 The Japan Society of Mechanical Engineers らないことが条件となっている．これらの PD 試験受験者の実績が公開され (3) ，検査のばらつきを確率論的に取 り扱うことが可能となった．また，SCC に対する確率論的破壊力学(Probabilistic Fracture Mechanics．以下，PFM) 解析コードも整備され (4) (5)…”

Stress Measurement of Stainless Steel Piping Welds by Complementary Use of High-Energy Synchrotron X-rays and Neutrons

“…In recent years, probabilistic fracture mechanics (PFM) has emerged as a significant method for evaluating the integrity of nuclear components prone to SCC. Several PFM codes specifically designed for piping applications have been developed [3][4][5][6]. PFM evaluations involving SCC require specific input parameters, such as SCC initiation time, crack growth rate, and residual stress distribution, within the assessment section.…”

Object-Oriented Software for Fitness-For-Service Assessment of Cracked Cylinder Based on API RP 579

“…To enhance FFS assessment activities, Filiou et al [2] suggested the development of FFS software. Researchers from universities, organizations, and companies have attempted to develop these software packages [3][4][5][6][7][8][9][10][11][12][13][14]. The computational basis within these packages may refer to a single specific FFS standard [3,6,9,11,14], an integration of several FFS standards [12,13], or a direct implementation of a fracture mechanics methodology without referring to any standard [4,5,7,8,10].…”