Characterization and Structural Integrity Tests of Ex-Service Steam Generator Tubes

2008 ◽  
Author(s):  
Sandra Pagan ◽  
Xinjian Duan ◽  
Michael J. Kozluk ◽  
Brian Mills ◽  
Guylaine Goszczynski
Keyword(s):  
Mechanical Properties ◽  
Power Generation ◽  
Steam Generator ◽  
Structural Integrity ◽  
Incoloy 800 ◽  
Full Power ◽  
Monel 400 ◽  
Integrity Tests ◽  
Steam Generator Tubes

Canadian nuclear standard CSA N285.4 requires the periodic metallurgical examination of removed ex-service steam generator tubes. This paper describes the practices used for the characterization and structural integrity tests of ex-service steam generator tubes at Ontario Power Generation (OPG). It shows that there is no degradation in mechanical properties of Monel 400 tubes after 7 to 18 Effective Full Power Years (EFPY) of operation and Incoloy 800 tubes after more than 10 EFPY of operation.

Characterization and structural integrity tests of ex-service steam generator tubes at Ontario Power Generation

2009 ◽  
Vol 239 (3) ◽  
pp. 477-483 ◽  
Author(s):  
Sandra Pagan ◽  
Xinjian Duan ◽  
Michael J. Kozluk ◽  
Brian Mills ◽  
Guylaine Goszczynski
Keyword(s):  
Power Generation ◽  
Steam Generator ◽  
Structural Integrity ◽  
Integrity Tests ◽  
Steam Generator Tubes

Evaluation of Interaction Effects on Part-Through Cracks in Steam Generator Tubes

2013 ◽  
Author(s):  
Yong-Seok Kang ◽  
Hong-Deok Kim ◽  
Kuk-Hee Lee ◽  
Jai-Hak Park
Keyword(s):  
Steam Generator ◽  
Interaction Effect ◽  
Structural Integrity ◽  
Structural Parameters ◽  
Interaction Effects ◽  
Multiple Cracks ◽  
Performance Limit ◽  
Steam Generator Tubing ◽  
Steam Generator Tubes

Degraded steam generator tubing can affect its safety functions. Therefore, its integrity should be maintained for each degradation form and all detected degradation must be assessed to verify that if adequate integrity is retained. Determination of tube integrity limits includes identifying acceptable structural parameters such as flaw length, depth, and amplitude of signals. If we consider just single-cracked tubes, short and deep flaws are not likely to threaten structural integrity of tubes. But if it has multiple-cracks, we have to consider interaction effects of multiple adjacent cracks on its burst pressure. Because adjacent multiple cracks can be merged due to the crack growth then it can challenge against the structural performance limit. There are some studies on the interaction effects of adjacent cracks. However, existing works on the interaction effect consider only through-wall cracks. No study has been carried out on the interaction effects of part-through cracks. Most cracks existing in real steam generator tubing are not through-wall cracks but part-through cracks. Hence, integrity of part-through cracks is more practical issue than that of through-wall cracks. This paper presents experimental burst test results with steam generator tubing for evaluation of interaction effects with axial oriented two collinear and parallel part-through cracks. The interaction effect between two adjacent cracks disappeared when the distance exceeds about 2 mm.

Fitness-for-Service Assessment of Steam Generator Tubing Subject to Dealloying Degradation

2017 ◽  
Author(s):  
Rosita Mousavi ◽  
Xinjian Duan ◽  
Michael Kozluk ◽  
Min Wang ◽  
Yihai Shi
Keyword(s):  
Steam Generator ◽  
Degradation Mechanism ◽  
Life Cycle Management ◽  
Steam Generators ◽  
Nickel Copper ◽  
Steam Generator Tubing ◽  
Management Plans ◽  
Monel 400 ◽  
Technical Basis ◽  
Steam Generator Tubes

A new degradation mechanism has been observed in Monel 400 Steam Generator tubing material, a nickel-copper alloy (63Ni-28Cu-2½Fe) with the ASME material designation SB-163/N04400. The location is above the top preheater support plate of the two re-circulating steam generator in one of the units of the Pickering Nuclear Generating Station. This paper provides a brief description of the regulatory environment, OPG’s steam generator life cycle management plans, the Canadian Industry’s fitness-for-service guidelines for steam generator tubes, and the afflicted steam generators. The paper then goes on to discuss the following activities that were conducted to support the technical basis to justify that the steam generators fit to be returned to service: • Inspection scope expansion, methods, and results. • Examination of removed tubes. • Condition monitoring assessment. • Operational assessment. • Burst-pressure tests of removed tubes and of fabricated test specimens. • Degradation specific flaw model and acceptance standards. • Flaw growth rate predictions. • Plugging limit adopted.

Structural Integrity Assessment of Steam Generator Tube by the Use of Heterogeneous Finite Element Method

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Xinjian Duan ◽  
Michael J. Kozluk ◽  
Sandra Pagan ◽  
Brian Mills
Keyword(s):  
Finite Element ◽  
Steam Generator ◽  
Failure Modes ◽  
Structural Integrity ◽  
Fretting Wear ◽  
Defect Depth ◽  
Steam Generator Tube ◽  
Integrity Assessment ◽  
Failure Pressure ◽  
Steam Generator Tubes

Aging steam generator tubes have been experiencing a variety of degradations such as pitting, fretting wear, erosion-corrosion, thinning, cracking, and denting. To assist with steam generator life cycle management, some defect-specific flaw models have been developed from burst pressure testing results. In this work, an alternative approach; heterogeneous finite element model (HFEM), is explored. The HFEM is first validated by comparing the predicted failure modes and failure pressure with experimental measurements of several tubes. Several issues related to the finite element analyses such as temporal convergence, mesh size effect, and the determination of critical failure parameters are detailed. The HFEM is then applied to predict the failure pressure for use in a fitness-for-service condition monitoring assessment of one removed steam generator tube. HFEM not only calculates the correct failure pressure for a variety of defects, but also predicts the correct change of failure mode. The Taguchi experimental design method is also applied to prioritize the flaw dimensions that affect the integrity of degraded steam generator tubes such as the defect length, depth, and width. It has been shown that the defect depth is the dominant parameter controlling the failure pressure. The failure pressure varies almost linearly with defect depth when the defect length is greater than two times the tube diameter. An axial slot specific flaw model is finally developed.

A Review of Some Degradation Mechanisms in CANDU Steam Generator Tubing

2006 ◽  
Author(s):  
G. Ogundele ◽  
M. Clark ◽  
G. Goszczynski ◽  
A. Lloyd ◽  
S. Pagan ◽  
...  
Keyword(s):  
Steam Generator ◽  
Operating Conditions ◽  
Degradation Mechanisms ◽  
Operating Period ◽  
Inconel 600 ◽  
Causative Factors ◽  
Steam Generator Tubing ◽  
Incoloy 800 ◽  
Heavy Water Reactor ◽  
Monel 400

The first CANDU (CANadian Deuterium Uranium) pressurized heavy water reactor (PHWR) went into operation in July 1971. Today, there are several units in operation at the Pickering, Bruce, and Darlington sites in Ontario, Canada. The steam generator tubing materials were manufactured from Monel 400, Inconel 600, and Incoloy 800 for the Pickering, Bruce, and Darlington respectively and are subjected to different operating conditions. This paper presents a review of some of the various types of degradation mechanisms that have been observed on these tubing materials over the operating period of the respective plants. The results presented are based on the metallurgical examination of removed tubes. The mechanisms that have been observed include pitting, stress corrosion cracking, intergranular attack, fretting, and erosion corrosion. The nature of the flaws and causative factors (if known) are discussed.

Structural integrity assessments of steam generator tubes using the FAD methodology

2015 ◽  
Vol 295 ◽  
pp. 457-467 ◽  
Author(s):  
Marcos A. Bergant ◽  
Alejandro A. Yawny ◽  
Juan E. Perez Ipiña
Keyword(s):  
Steam Generator ◽  
Structural Integrity ◽  
Steam Generator Tubes ◽  
Integrity Assessments
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