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Author:
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ISBN:
Category :
Languages : en
Pages : 38
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Book Description
The life of the High Flux Isotope Reactor (HFIR) pressure vessel is limited by a radiation induced reduction in the material's fracture toughness. Hydrostatic proof testing and probabilistic fracture mechanics analyses are being used to meet the intent of the ASME Code, while extending the life of the vessel well beyond its original design value. The most recent probabilistic evaluation is more precise and accounts for the effects of gamma as well as neutron radiation embrittlement. This analysis confirms the earlier estimates of a permissible vessel lifetime of at least 50 EFPY (100 MW).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
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Book Description
The life of the High Flux Isotope Reactor (HFIR) pressure vessel is limited by a radiation induced reduction in the material's fracture toughness. Hydrostatic proof testing and probabilistic fracture mechanics analyses are being used to meet the intent of the ASME Code, while extending the life of the vessel well beyond its original design value. The most recent probabilistic evaluation is more precise and accounts for the effects of gamma as well as neutron radiation embrittlement. This analysis confirms the earlier estimates of a permissible vessel lifetime of at least 50 EFPY (100 MW).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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The state of the vessel steel embrittlement as a result of neutron irradiation can be measured by its increase in the nil ductility temperature (NDT). This temperature is sometimes referred to as the brittle-ductile transition temperature (DBT) for fracture. The life extension of the High Flux Isotope Reactor (HFIR) vessel is calculated by using the method of fracture mechanics. A new method of fracture probability calculation is presented in this paper. The fracture probability as a result of the hydrostatic pressure test (hydrotest) is used to determine the life of the vessel. The hydrotest is performed in order to determine a safe vessel static pressure. It is then followed by using fracture mechanics to project the safe reactor operation time from the time of the satisfactory hydrostatic test. The life extension calculation provides the following information on the remaining life of the reactor as a function of the NDT increase: (1) the life of the vessel is determined by the probability of vessel fracture as a result of hydrotest at several hydrotest pressures and vessel embrittlement conditions, (2) the hydrotest time interval vs the NDT increase rate, and (3) the hydrotest pressure vs the NDT increase rate. It is understood that the use of a complete range of uncertainties of the NDT increase is equivalent to the entire range of radiation damage that can be experienced by the vessel steel. From the numerical values for the probabilities of the vessel fracture as a result of hydrotest, it is estimated that the reactor vessel life can be extended up to 50 EFPY (100 MW) with the minimum vessel operating temperature equal to 85°F.
Author:
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ISBN:
Category :
Languages : en
Pages : 17
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Book Description
Periodic hydrostatic proof testing and probabilistic fracture mechanics analyses are performed to demonstrate the structural integrity and useful life of the High Flux Isotope Reactor (HFIR) pressure vessel. Calculations of the hydro-test conditions (pressure, temperature, and frequency) and of the probability of failure account for vessel degradation (flaw growth and radiation-induced embrittlement) that takes place between tests and of the credible worst-case-operating condition. The specified useful life of the vessel is limited by specified maximum permissible calculated probabilities of failure for hydro-test and worst-case-operating conditions. The probability of failure can be calculated with or without accounting for the success (absence of failure) of a test, but if success is accounted for, the calculated probabilities are less and thus the maximum permissible life greater. This report describes a simple method for including the success of a test.
Author: John D. Landes
Publisher: ASTM International
ISBN: 0803119909
Category : Electronic book
Languages : en
Pages : 805
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Book Description
Author: J.W. Provan
Publisher: Springer Science & Business Media
ISBN: 9401727643
Category : Science
Languages : en
Pages : 477
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Book Description
With the advent of the 80's there has been an increasing need for analytic and numerical techniques, based on a thorough understanding of microstructural processes, that express in a manner suitable for practicing engineers the reliability of components and structures that are being subjected to degradation situations. Such situations fall within the framework offracture mechanics, fatigue, corrosion fatigue and pitting corrosion. Luckily, such techniques are now being developed and it was felt timely to combine in one volume reports by the leaders in this field who are currently making great strides towards solving these problems. Hence the idea of this monograph was born and I am pleased to be associated both with it and the contributors whose chapters are included in this volume. A very large part of the credit for this monograph must go to the authors who have taken time out from their busy schedules to prepare their submissions. They have all worked diligently over the last few months in order to get their manuscripts to me on time and I sincerely thank them for their help throughout the preparation of this volume.
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Category :
Languages : en
Pages : 24
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Book Description
The probability of fracture versus a range of applied hoop stresses along the High Flux Isotope Reactor vessel is obtained as an estimate of its fracture capacity. Both the crack size and the fracture toughness are assumed to be random variables and subject to assumed distribution functions. Possible hoop stress is based on the numerical solution of the vessel response by applying a point pressure-pulse at the center of the fluid volume within the vessel. Both the fluid-structure interaction and radiation embrittlement are taken into consideration. Elastic fracture mechanics is used throughout the analysis. The probability function of fracture for a single crack due to either a variable crack depth or a variable toughness is derived. Both the variable crack size and the variable toughness are assumed to follow known distributions. The probability of vessel fracture with multiple number of cracks is then obtained as a function of the applied hoop stress. The probability of fracture function is, then, extended to include different levels of confidence and variability. It, therefore, enables one to estimate the high confidence and low probability fracture capacity of the reactor vessel under a range of accident loading conditions.
Author: S-J Chang
Publisher:
ISBN:
Category : Embrittlement
Languages : en
Pages : 16
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Book Description
The probability of fracture versus a range of applied hoop stresses along the high flux isotope reactor (HFIR) vessel is obtained as an estimate of its fracture capacity. Both the crack size and the fracture toughness are assumed to be random variables and subject to assumed distribution functions. Possible hoop stress is based on the numerical solution of the vessel response by applying a point pressure-pulse at the center of the fluid volume within the vessel. Both the fluid-structure interaction and radiation embrittlement are taken into consideration. Elastic fracture mechanics is used throughout the analysis. The probability function of fracture for a single crack due to either a variable crack depth or a variable toughness is derived. Both the variable crack size and the variable toughness are assumed to follow known distributions. The probability of vessel fracture with a multiple number of cracks is then obtained as a function of the applied hoop stress. The probability of fracture function is, then, extended to include different levels of confidence and variability. It, therefore, enables one to estimate the high confidence and low probability fracture capacity of the reactor vessel under a range of accident loading conditions.
Author: C. Sundararajan
Publisher:
ISBN:
Category : Fracture mechanics
Languages : en
Pages : 226
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Book Description
Author: DG. Ball
Publisher:
ISBN:
Category : Fracture mechanics
Languages : en
Pages : 16
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Book Description
As a part of the Nuclear Regulatory Commission (NRC) effort to obtain a resolution to the pressurized water reactor (PWR) pressurized-thermal-shock (PTS) issue, a probabilistic approach has been applied that includes a probabilistic fracture-mechanics (PFM) analysis. The PFM analysis is performed with OCA-P, a computer code that performs thermal, stress, and fracture-mechanics analyses and estimates the conditional probability of vessel failure, P(F|E), using Monte Carlo techniques. The stress intensity factor (K1) is calculated for two- and three-dimensional surface flaws using superposition techniques and influence coefficients. Importance-sampling techniques are used, as necessary, to limit to a reasonable value the number of vessels actually calculated.
Author: J. M. Bloom
Publisher: ASTM International
ISBN: 9780803102422
Category : Technology & Engineering
Languages : en
Pages : 228
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Book Description
