Technical Basis for Proposed Fourth Revision to ASME Code Case N-513

2014 ◽  
Author(s):  
Robert O. McGill ◽  
Guy DeBoo ◽  
Russell C. Cipolla ◽  
Eric J. Houston
Keyword(s):  
Nuclear Regulatory Commission ◽  
Short Term ◽  
Safety Issues ◽  
Evaluation Procedures ◽  
The Us ◽  
Bent Pipe ◽  
Asme Code ◽  
Moderate Energy ◽  
Regulatory Commission ◽  
Technical Basis

Code Case N-513 provides evaluation rules and criteria for temporary acceptance of flaws, including through-wall flaws, in moderate energy piping. The application of the Code Case is restricted to moderate energy, Class 2 and 3 systems, so that safety issues regarding short-term, degraded system operation are minimized. The first version of the Code Case was published in 1997. Since then, there have been three revisions to augment and clarify the evaluation requirements and acceptance criteria of the Code Case that have been published by ASME. The technical bases for the original version of the Code Case and the three revisions have been previously published. There is currently work underway to incorporate additional changes to the Code Case and this paper provides the technical basis for the changes proposed in a fourth revision. These changes include addressing the current condition on the Code Case acceptance by the US Nuclear Regulatory Commission (NRC), clarification of the Code Case applicability limits and expansion of Code Case scope to additional piping components. New flaw evaluation procedures are given for through-wall flaws in elbows, bent pipe, reducers, expanders and branch tees. These procedures evaluate flaws in the piping components as if in straight pipe by adjusting hoop and axial stresses to account for the geometry differences. These changes and their technical bases are described in this paper.

Technical Basis for Cases N-629 and N-631 as an Alternative for RTNDT Reference Temperature

2007 ◽  
Author(s):  
J. G. Merkle ◽  
K. K. Yoon ◽  
W. A. VanDerSluys ◽  
W. Server
Keyword(s):  
Pressure Vessel ◽  
Nuclear Power ◽  
Power Plants ◽  
Threshold Level ◽  
Nuclear Regulatory Commission ◽  
New Approach ◽  
The Us ◽  
Asme Code ◽  
Regulatory Commission ◽  
Technical Basis

ASME Code Cases N-629/N-631, published in 1999, provided an important new approach to allow material specific, measured fracture toughness curves for ferritic steels in the code applications. This has enabled some of the nuclear power plants whose reactor pressure vessel materials reached a certain threshold level based on overly conservative rules to use an alternative RTNDT to justify continued operation of their plants. These code cases have been approved by the US Nuclear Regulatory Commission and these have been proposed to be codified in Appendix A and Appendix G of the ASME Boiler and Pressure Vessel Code. This paper summarizes the basis of this approach for the record.

Technical Basis for Proposed Fifth Revision to ASME Code Case N-513

2018 ◽  
Author(s):  
Dylan Cimock ◽  
Eric J. Houston ◽  
Russell C. Cipolla ◽  
Robert O. McGill
Keyword(s):  
Gate Valve ◽  
Evaluation Procedure ◽  
Straight Pipe ◽  
System Operation ◽  
Short Term ◽  
Valve Body ◽  
Safety Issues ◽  
Asme Code ◽  
Moderate Energy ◽  
Technical Basis

Code Case N-513 provides evaluation rules and criteria for temporary acceptance of flaws, including through-wall flaws, in moderate energy piping. The application of the Code Case is restricted to moderate energy, Class 2 and 3 systems, so that safety issues regarding short-term, degraded system operation are minimized. The first version of the Code Case was published in 1997. Since then, there have been four revisions to augment and clarify the evaluation requirements and acceptance criteria of the Code Case that have been published by ASME. The technical bases for the original version of the Code Case and the four revisions have been previously published [1, 2, and 3]. There is currently work underway to incorporate additional changes to the Code Case and this paper provides the technical basis for the changes proposed in a fifth revision. These changes include clarification for buried piping, investigation of various radii used in the Code Case, removal of the 0.1 limit on the flexibility characteristic for elbow flaw evaluation, and an update of the stress intensity factor parameters for circumferential through-wall flaws. In addition, a new flaw evaluation procedure is given for through-wall flaws in gate valve body ends. This procedure evaluates flaws in the end of the valve body as if in straight pipe. These changes and their technical bases are described in this paper. Clarifications and changes deemed editorial are not documented in this paper.

Technical Basis for Acceptance of Flaws in Moderate Energy Class 2 and 3 Vessels and Tanks

2004 ◽  
Author(s):  
Pat L. Strauch ◽  
Warren H. Bamford ◽  
Sushil K. Daftuar
Keyword(s):  
Structural Integrity ◽  
Growth Curves ◽  
Nuclear Regulatory Commission ◽  
Operating Conditions ◽  
Energy Class ◽  
Asme Code ◽  
Moderate Energy ◽  
Leakage Monitoring ◽  
Regulatory Commission ◽  
Technical Basis

New procedures and acceptance criteria for the evaluation of degradation, including through-wall flaws, in moderate energy Class 2 and 3 vessels and tanks have been prepared for implementation within Section XI of the ASME Code. The provisions are contained in a proposed Code Case and are focused on the structural integrity margin of the vessel or tank against gross failure. The assessment of the degraded condition is based on the flaw evaluation procedures already established in ASME Section XI. Additional provisions for periodic inspection and leakage monitoring are included to assure that analysis assumptions are conservative for the operating conditions. The precedent for permitting operation with degraded components was established in United States Nuclear Regulatory Commission (NRC) Generic Letter 90-05 and Code Case N-513-1 for piping, as well as several NRC-accepted plant-specific relief requests associated with leaking tanks. The technical basis for the procedures is presented, and the objectives and scope of its application are explained. The basis for the analytical procedures follows from evaluation rules contained in ASME Section XI, Appendix A. Other issues regarding consequences of leakage, growth of degradation, and augmented inspections and surveillance are also addressed, as well as reference crack growth curves for stress corrosion cracking for conditions appropriate for application of these procedures.

Technical Basis for Proposed ASME Code Case Based on N-513 for Higher Pressure Applications

2017 ◽  
Author(s):  
Robert O. McGill ◽  
Ronald J. Janowiak ◽  
Eric J. Houston ◽  
Do Jun Shim
Keyword(s):  
Structural Integrity ◽  
Temperature Limit ◽  
System Operation ◽  
Short Term ◽  
Safety Issues ◽  
Asme Code ◽  
Moderate Energy ◽  
Technical Basis ◽  
Thrust Forces ◽  
Case Based

Code Case N-513 provides evaluation rules and criteria for temporary acceptance of flaws, including through-wall flaws, in moderate energy piping. The application of the Code Case is restricted to Class 2 and 3 systems, so that safety issues regarding short-term system operation are minimized. The first version of the Code Case was published in 2000. Since then, there have been four revisions to the Code Case that have been published by ASME. The technical bases for the original version of the Code Case and the four revisions have been previously published. There is currently work underway to employ the methods given in N-513 for a new and separate Code Case for higher pressure piping applications. This paper provides the technical basis for the proposed Code Case that includes a structural integrity evaluation and consideration of potential jet thrust forces. In addition, discussion is provided on additional Code Case requirements considering the application to higher pressure systems in order to bolster defense-in-depth. Note that the proposed Code Case still maintains the temperature limit given in N-513.

Technical Basis for Proposed Revisions to ASME Code Case N-513 and Some Applications to Moderate Energy Piping

2006 ◽  
Author(s):  
Robert O. McGill ◽  
Nathaniel G. Cofie ◽  
Russell C. Cipolla ◽  
Guy DeBoo
Keyword(s):  
Original Version ◽  
System Operation ◽  
Short Term ◽  
Safety Issues ◽  
Asme Code ◽  
Moderate Energy ◽  
Technical Basis ◽  
Planar Flaw

Code Case N-513 provides evaluation rules and criteria for temporary acceptance of flaws, including through-wall flaws, in moderate energy piping. The application of the Code Case is restricted to Class 2 and 3 systems, so that safety issues regarding short-term system operation are minimized. The first version of the Code Case was published in 2000. Since then, there have been two revisions to the Code Case (N-513-1 [1] and N-513-2 [2]) that have been published by ASME. There is currently work underway to incorporate additional changes to the Code Case to make it easier to apply to through-wall, nonplanar flaws. The technical basis for the original version of the Code Case and the first revision, N-513-1, has been previously published [3]. This paper provides the technical basis for the changes in the second revision of the Code Case, N-513-2, and the proposed changes to a third revision. These changes specifically address exceptions taken by the NRC in the first version of the Code Case and more importantly provide flaw evaluation rules for through-wall, nonplanar flaws. The flaw evaluation rules for through-wall, nonplanar flaws are based on ASME Code Section III branch reinforcement rules and also a quasi planar flaw approach. These developments are described in the paper. In addition, practical examples involving the application of the Code Case to through-wall, nonplanar flaws are also provided.

Application Examples of ASME Code Case N-513 Implementation

2019 ◽  
Author(s):  
Robert O. McGill ◽  
Russell C. Cipolla ◽  
Eric J. Houston ◽  
Ronald J. Janowiak
Keyword(s):  
Gate Valve ◽  
Operating Experience ◽  
Straight Pipe ◽  
System Operation ◽  
Short Term ◽  
Valve Body ◽  
Safety Issues ◽  
Plant Safety ◽  
Asme Code ◽  
Moderate Energy

Abstract Code Case N-513 provides evaluation rules and criteria for temporary acceptance of flaws, including through-wall flaws, in moderate energy piping. The application of the Code Case is restricted to Class 2 and 3 systems, so that safety issues regarding short-term system operation are minimized. The first version of the Code Case was published in 1997. Since then, there have been five revisions to the Code Case that have been published by ASME. The Code Case has been used numerous times by utilities to avoid unscheduled shutdowns without impacting plant safety. Recent revisions of Code Case N-513 continue to expand its scope to piping components including elbows, reducers, branch tees and gate valve body ends. This paper provides three application examples of the Code Case implementation based on US plant operating experience. Specifically, detailed evaluations of through-wall leakage in straight pipe, a piping elbow and gate valve body end are provided. These examples will help facilitate Code Case implementation by future users.

Evolution of Section XI of the ASME Boiler and Pressure Vessel Code

2000 ◽  
Vol 122 (3) ◽  
pp. 234-241 ◽  
Author(s):  
Owen F. Hedden
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Nuclear Regulatory Commission ◽  
Operating Conditions ◽  
Nondestructive Examination ◽  
The Us ◽  
Regulatory Commission ◽  
Technical Basis ◽  
Year 2000

This article will describe the development of Section XI from a pamphlet-sized document to the lengthy and complex set of requirements, interpretations, and Code Cases that it has become by the year 2000. Section XI began as a set of rules for inservice inspection of the primary pressure boundary system of nuclear power plants. It has evolved to include other aspects of maintaining the structural integrity of safety class pressure boundaries. These include procedures for component repair/replacement activities, analysis of revised and new plant operating conditions, and specialized provisions for nondestructive examination of components and piping. It has also increased in scope to cover other Section III construction: Class 2, Class 3 and containment structures. First, to provide a context for the discussions to follow, the differences in administration and enforcement between Section XI and the other Code Sections will be explained, including its dependence on the US Nuclear Regulatory Commission. The importance of interpretations and Code Cases then will be discussed. The development of general requirements and requirements for each class of structure will be traced. The movement of Section XI toward a new philosophy, risk-informed inspection, will also be discussed. Finally, an annotated bibliography of papers describing the philosophy and technical basis behind Section XI will be provided. [S0094-9930(00)01703-0]

Risk-Based Fracture Evaluation of Reactor Vessels Subjected to Cool-Down Transients Associated With Shutdown: An Examination of the Effects of Different Modeling Approaches on Estimated Failure Probabilities

2006 ◽  
Author(s):  
T. L. Dickson ◽  
M. T. EricksonKirk
Keyword(s):  
Nuclear Reactor ◽  
Structural Integrity ◽  
Nuclear Regulatory Commission ◽  
The United States ◽  
Pressure Vessels ◽  
Asme Code ◽  
Computational Methodology ◽  
Regulatory Commission ◽  
Technical Basis ◽  
Evaluation Project

The current regulations, as set forth by the United States Nuclear Regulatory Commission (USNRC), to insure that light-water nuclear reactor pressure vessels (RPVs) maintain their structural integrity when subjected to planned startup (heat-up) and shutdown (cool-down) transients are specified in Appendix G to 10 CFR Part 50, which incorporates by reference Appendix G to Section XI of the ASME Code. In 1999, the USNRC initiated the interdisciplinary Pressurized Thermal Shock (PTS) Re-evaluation Project to determine if a technical basis could be established to support a relaxation in the current PTS regulations. The PTS re-evaluation project included the development and application of an updated risk-based computational methodology that incorporates several advancements applicable to modeling the physics of vessel fracture due to thermal hydraulic transients imposed on the RPV inner surface. The results of the PTS re-evaluation project demonstrated that there is a sound technical basis to support a relaxation of the current PTS regulations. The results of the PTS re-evaluation are currently under review by the USNRC. Based on the promising results of the PTS re-evaluation, the USNRC has recently applied the updated computational methodology to fracture evaluations of RPVs subjected to planned cool-down transients, associated with reactor shutdown, derived in accordance with ASME Section XI – Appendix G. The objective of these analyses is to determine if a sound technical basis can be established to provide a relaxation to the current regulations for the derivation of bounding cool-down transients as specified in Appendix G to Section XI of the ASME Code. This paper provides a brief overview of these analyses, results, and the implications of the results.

Inspection Optimization Justification for PWR Main Steam and Feedwater Nozzles Using Probabilistic Fracture Mechanics

2019 ◽  
Author(s):  
C. Lohse ◽  
D. J. Shim ◽  
D. Somasundaram ◽  
R. Grizzi ◽  
G. L. Stevens ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Nuclear Regulatory Commission ◽  
Pressure Vessels ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Asme Code ◽  
Sensitivity Studies ◽  
Main Steam ◽  
Regulatory Commission ◽  
Technical Basis

Abstract Pressurized water reactor (PWR) steam generator (SG) main steam and feedwater nozzles are classified as ASME Code, Section XI, Class 2, Category C-B, pressure retaining welds in pressure vessels. Current ASME Code requirements specify that the nozzle-to-shell welds (Item No. C2.21 & C2.32) and nozzle inner radius sections (Item C2.22) are to be examined very 10 years. An evaluation was performed to establish a technical basis for optimized inspection frequencies for these items. The work included a review of inspection history and results, a survey of components in the PWR fleet (which included both U.S. and overseas plants), selection of representative main steam and feedwater nozzle configurations and operating transients for stress analysis, evaluation of potential degradation mechanisms, and flaw tolerance evaluations consisting of probabilistic and deterministic fracture mechanics analyses. The results of multiple inspection scenarios and sensitivity studies were compared to the U.S. Nuclear Regulatory Commission (NRC) safety goal of 10−6 failures per year.

Issues Regarding Use of Master Curve Data in Resetting Initial RTNDT

2006 ◽  
Author(s):  
K. K. Yoon ◽  
J. B. Hall
Keyword(s):  
National Laboratory ◽  
Safety Evaluation ◽  
Nuclear Regulatory Commission ◽  
Crack Size ◽  
Oak Ridge ◽  
The Us ◽  
Large Populations ◽  
Asme Code ◽  
Shock Experiment ◽  
Regulatory Commission

The B&W Owners Group submitted justification for resetting the initial RTNDT for the Linde 80 weld materials using ASME Code Case N-629/N-631 to the US Nuclear Regulatory Commission and received the NRC Safety Evaluation Report with some adjustments. Two major issues were encountered during the review and approval process: 1) The pressurized thermal shock experiment data from Oak Ridge National Laboratory with full-length axial (very long) cracks fall below the Code Case curve. This observation led to the question whether there are implicit crack size limitations in the code case, and 2) For the large populations of data examined, a larger portion of data falls below the Code Case N-629/N-631 curve than the ASME KIC curve, prompting a question whether the code case is functionally equivalent to the ASME KIC curve. This paper describes these major issues and how they were addressed.

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