In-Service Inspection Strategy for Alloy X-750 BWR Jet Pump Beams Based Upon Linear Elastic Fracture Mechanics Analysis

2009 ◽  
Author(s):  
Daniel V. Sommerville ◽  
Hardayal Mehta ◽  
Robert Carter ◽  
Jonathon Kubiak
Keyword(s):  
Fracture Mechanics ◽  
Pump Beam ◽  
Operating Experience ◽  
Linear Elastic Fracture Mechanics ◽  
Jet Pump ◽  
Linear Elastic ◽  
Flaw Tolerance ◽  
Beam Design ◽  
Jet Pumps ◽  
Elastic Fracture

Jet pumps in a boiling water reactor (BWR) are located in the annulus region between the core shroud and the reactor vessel wall and provide core flow to control reactor power. Between 16 and 24 jet pumps are included in BWR/3 through BWR/6 plants, depending on the plant rating. The inlet mixer assembly of the jet pump is secured in place with a hold down mechanism called a jet pump beam. This beam is fabricated of alloy X-750 and tensioned to 58–74% of the yield stress of the material, depending on the beam design. In recent years, more attention has been placed upon inter-granular stress corrosion cracking (IGSCC) of alloy X-750 BWR internal components as a result of in-service cracking and failures. BWR plant owners have implemented actions to manage IGSCC of jet pump beams and assemblies through increased inspections and changes to process specifications for X-750. However, a thorough understanding of the flaw tolerance of the jet pump beam was not available to guide the periodicity of inspections as well as to define critical flaw sizes needed to validate the capability of inspection techniques. This paper describes a linear elastic fracture mechanics (LEFM) evaluation in which the flaw tolerance of the existing jet pump beam designs is established and used to recommend inspection frequencies for the jet pump beam. Industry operating experience is used to assess the credibility of the results obtained from this evaluation. This work illustrates an example of the use of LEFM to develop a technically defensible basis for the required inspection regions and the frequency of inspection for an alloy X-750 BWR internal component and helps to establish the necessary sensitivity of non-destructive examination technology to be used to examine the component.

Alternative Acceptance Criteria for Flaws in Ferritic Steel Components Operating in the Upper Shelf Temperature Range

2012 ◽  
Author(s):  
H. L. Gustin ◽  
R. C. Cipolla ◽  
S. X. Xu ◽  
D. A. Scarth
Keyword(s):  
Fracture Mechanics ◽  
Ferritic Steel ◽  
Linear Elastic Fracture Mechanics ◽  
Acceptance Criteria ◽  
Temperature Range ◽  
Linear Elastic ◽  
Flaw Tolerance ◽  
Elastic Fracture ◽  
Shelf Temperature ◽  
Reactor Pressure

The flaw evaluation rules for ferritic vessels in IWB-3610, IWB-3620 and Appendix A of ASME Section XI are based on linear elastic fracture mechanics techniques and were developed primarily for the irradiated reactor pressure vessel beltline region and other low temperature carbon and low-alloy steel applications in which the material exhibits limited or no ductility prior to failure. There are situations in which ferritic steel components operate in the upper shelf temperature range and therefore exhibit significant ductility and increased flaw tolerance. Application of linear elastic fracture mechanics techniques to these cases can be very conservative. In order to address flaw evaluation of ferritic materials exhibiting upper shelf toughness and high ductility, the proposed Code Case N-749 of ASME Section XI was developed and is currently under committee review. This proposed Code Case provides alternate acceptance criteria for situations in which the component is operating in the upper shelf temperature range and therefore has adequate ductility to allow the use of elastic-plastic fracture mechanics techniques.

Fracture Mechanics Assessment of Hydrogen Storage Vessel

2021 ◽  
Author(s):  
Xiaoliang Jia ◽  
Zhiwei Chen ◽  
Fang Ji
Keyword(s):  
High Pressure ◽  
Fracture Mechanics ◽  
Hydrogen Storage ◽  
High Strength Steel ◽  
High Strength ◽  
Linear Elastic Fracture Mechanics ◽  
Storage Vessel ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Hydrogen Storage Vessel

Abstract High strength steel is usually used in fabrication of hydrogen storage vessel. The fracture toughness of high strength steel will be decreased and the crack sensitivity of the structures will be increased when high strength steels are applied in hydrogen environment with high pressure. Hence, the small cracks on the surface of pressure vessel may grow rapidly then lead to rupture. Therefore, this paper makes a series of research on how to evaluate the 4130X steel hydrogen storage vessel with fracture mechanics. This study is based on the assumption that there is a semi-elliptic crack on internal surface of hydrogen storage vessel. First of all, based on linear elastic fracture mechanics, the stress intensity factors and crack tolerance of 4130X steel hydrogen storage vessel have been calculated by means of finite element method based on interaction integral theory and polynomial-approximated approach from GB/T 34019 Ultra-high pressure vessels. Then, a comparative study has been made from the results of above methods to find out the difference between them. At last, the fatigue life of a 4130X steel hydrogen storage vessel has been predicted based on linear elastic fracture mechanics and Paris formula. The calculation methods and analysis conclusion can be used to direct the design and manufacture of hydrogen storage vessel.

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