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Portfolio of Analytical Tools for Reactor Component Integrity Assessment MissionThe Component Integrity Branch (CIB) in the Division of Engineering of the U.S. Nuclear Regulatory Commission's (NRC's) Office of Nuclear Regulatory Research develops and maintains a portfolio of software codes and capabilities to support a sound and independent regulatory decisionmaking process.
In addition to computational tools and expertise, CIB provides other offices directly involved in evaluating licensee applications with technical support and training related to CIB’s in-house analytical and software capabilities.
Probabilistic Analysis Codes
Fracture Analysis of Vessels—Oak Ridge (FAVOR)
Current version v16.1 (released in 2016)
Extremely Low Probability of Rupture (xLPR)
Current version v2.0 (to be released in 2019)
Deterministic Analysis Codes
Flaw Evaluation Software (FES)
Internal use only
Leak Analysis of Piping—Oak Ridge—Standalone (LEAPOR-SA)
Standalone version released in 2018
Finite Element Capabilities
Commercial Finite Element Software (ABAQUS)
Residual stress modeling
Crack growth modeling with extended finite element method (XFEM)
Probabilistic Fracture Mechanics Codes
Extremely Low Probability of Rupture (xLPR)A computer code used for calculating leak and rupture probabilities for nuclear power plant piping components.
A joint effort by the NRC’s Office of Nuclear Regulatory Research and the Electric Power Research Institute (EPRI), now in its second version.
Capable of modeling the effects of stress-corrosion cracking, fatigue, crack initiation, residual stresses, mechanical and chemical mitigation, and more.
Used by NRC and EPRI staff and contractors to risk-inform industrywide emerging piping integrity issues via probabilistic approaches.
Fracture Analysis of Vessels—Oak Ridge (FAVOR)A computer code used for assessing the probabilities of reactor pressure vessel (RPV) crack growth initiation and RPV failure.
Historically developed by Oak Ridge National Laboratory for the NRC and now maintained, distributed, and developed primarily by NRC staff.
Used to risk-inform the Alternate Pressurized Thermal Shock rule (10 CFR 50.61a), to update Regulatory Guide 1.230, and to address current RPV integrity issues such as shallow inner-surface flaws.
Used by domestic and international utilities, technical support organizations, and regulators, as well as NRC staff, to probabilistically evaluate and risk-inform RPV integrity issues.
Probabilistic fracture mechanics codes account for uncertainties by randomly sampling from input distributions.
FAVOR flaw modeling xLPR modeling scheme
Probabilistic fracture mechanics can be used to gain greater insights into the structural integrity of components.
Deterministic Component Integrity Tools
Flaw Evaluation Software (FES)Developed by CIB for use by the NRC staff in performing deterministic confirmatory analyses and sensitivity studies of piping welds susceptible to primary water stress-corrosion cracking (PWSCC).
FES estimates crack growth from PWSCC and the time to reach the American Society of Mechanical Engineers Boiler and Pressure Vessel Code limit of 75 percent though-wall, as well as the time to first leakage, subsequent leak rate, and, for circumferentially oriented flaws, the time to rupture.
FES uses methods from xLPR to calculate the time margin between Code-allowable crack depth, detectable leakage (defined by the user), and pipe rupture.
Leak Analysis of Piping—Oak Ridge—Standalone (LEAPOR-SA): Leak Before BreakA graphical user interface developed by CIB used to call the LEAPOR (Leak Analysis of Piping—Oak Ridge) two-phase leak rate code and return tabular results.
LEAPOR-SA provides a user-friendly method of entering the necessary parameters, including crack morphology parameters, that are needed to calculate leak rates for ranges of flaw lengths and crack opening displacements.
LEAPOR is a part of the xLPR code. It was programmed using the models employed in the SQUIRT leak rate code (NUREG/CR-5128, Rev. 1, and NUREG/CR-6004).
Deterministic fracture mechanics computational tools and analyses can be used to rapidly evaluate a specific set of assumptions.
Effect of initial flaw depth on PWSCC crack growth for a 3.0-millimeter inlay thickness
Finite Element Modeling Capabilities
Residual Stress ModelingResidual stress predictions are needed to improve the accuracy of component integrity analyses. Residual stresses resulting from welding and from PWSCC mitigation operations are of particular interest.
CIB uses the ABAQUS finite element software, coupled with pre- and post-processing tools, as well as custom subroutines developed in-house to predict residual stresses in nuclear plant components.
CIB has developed capabilities to reliably produce high-quality weld residual stress predictions for use in confirmatory regulatory analyses.
Crack Growth Modeling with Extended Finite Element Modeling (XFEM)Crack growth in complex geometries and as a result of complex three-dimensional weld configurations cannot readily be predicted with simple analytical tools or standard solutions.
CIB has developed the procedures required to predict natural crack growth using XFEM in ABAQUS.
These capabilities are being benchmarked via ongoing participation in Organization for Co-operation and Development round-robin studies.
Finite element modeling can be used to perform indepth studies of more complex phenomena. Currently, CIB uses ABAQUS. Temperature
during Welding Weld Residual Stress XFEM Crack Growth
Contact Information
Probabilistic Analysis Codes
Fracture Analysis of Vessels—Ridge (FAVOR)
Patrick Raynaud: [email protected]
Extremely Low Probability of Rupture (xLPR)
Matthew Homiack: [email protected]
Deterministic Analysis Codes
Flaw Evaluation Software (FES)
Jay Wallace: [email protected]
Leak Analysis of Piping—Oak Ridge—Standalone (LEAPOR-SA)
Jay Wallace: [email protected]
Finite Element Capabilities
Commercial Finite Element Software (ABAQUS)
Giovanni Facco: [email protected]
Patrick Raynaud: [email protected]
