Assessing Steady-State Neutron Exposure Effects Through Analyses of Reactor Vessel Surveillance Data

2009 ◽  
pp. 155-155-11
Author(s):  
TR Mager ◽  
TU Martson ◽  
SE Yanichko
Keyword(s):  
Steady State ◽  
Reactor Vessel ◽  
Surveillance Data ◽  
Neutron Exposure

Creep Damage Assessment of a Low Alloy Pressure Vessel With Dissimilar Metal Welded Joint

2020 ◽  
Author(s):  
Robert Loomis ◽  
Srikanth Srigiriraju ◽  
Arindam Chakraborty
Keyword(s):  
Steady State ◽  
Carbon Steel ◽  
Creep Damage ◽  
Reactor Vessel ◽  
Flaw Size ◽  
Normal Operation ◽  
Low Alloy Steel ◽  
Design Life ◽  
First Case ◽  
Adjustment Factors

Abstract Creep damage in low alloy steel plates welded using carbon steel filler can be of concern for petroleum and petrochemical industry due to differential thermal strain and creep behavior. An aggravated scenario can occur when a flaw is present at the weld. The current work considers a catalytic reactor vessel in steady-state operation whose design life is consumed by 80%. It is assumed that after few years of initial operation a low alloy steel patch (similar to the vessel plate) was welded to the vessel using carbon steel filler. A crack like flaw is assumed to be present currently and was sized using non-destructive testing. However, uncertainty remains regarding the time when the crack first appeared, which is often a representative case for a vessel in operation for many years. The objective of the current study is to, by following API 579-1/ASME FFS-1 code procedures, assess the creep damage at the end of the design life considering the postulated scenario as described above. Two cases are considered. For the first case, the currently observed flaw was assumed to be present as is since the beginning of time when the welded patch was made. No flaw growth is assumed for this case from initial time till present. This represents a conservative upper bound case. For the second case, it is assumed that a smaller initial flaw grew to the current size during normal operation. The initial flaw size was determined iteratively such that after growth it matches the currently determined flaw size. For the ease of calculations, the time from initiation of the flaw to the present was discretized into three time intervals during which it is assumed that the flaw size remains constant for the time interval. This removes some of the conservatism inherent in the first case. For both the cases, additional accumulated creep damage is determined considering crack growth. A Finite Element Analysis (FEA) is performed for the reactor vessel patch consisting of a single crack at the weld-patch interface to assess the accumulated creep damage from normal operation till the end of design life. Due to inherent uncertainties in the parameters, sensitivity studies on creep damage due to Adjustment Factors were also performed, based on which Adjustment Factors for Creep Strain Rate (material scatter) and Creep Ductility were chosen appropriately. Steady-state crack growth is considered for creep damage using analytical approach. The current work shows a practical approach combining FEA and analytical calculations to determine accumulated creep damage where a crack appears to have initiated sometime during the past normal operation.

Neutron Exposure of the PM-2A Reactor Vessel

1967 ◽  
Vol 27 (2) ◽  
pp. 348-359 ◽  
Author(s):  
K. Shure ◽  
Carl T. Oberg
Keyword(s):  
Reactor Vessel ◽  
Neutron Exposure

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 544-545
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
Steady State ◽  
Room Temperature ◽  
Small Mass ◽  
Equilibrium Pressure ◽  
Biological Objects ◽  
Mechanical Pump ◽  
Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

Observations oh Nucleation and Growth of Voids in Nickel

1970 ◽  
Vol 28 ◽  
pp. 414-415
Author(s):  
J. L. Brimhall ◽  
H. E. Kissinger ◽  
B. Mastel
Keyword(s):  
High Purity ◽  
Growth Stage ◽  
Elevated Temperatures ◽  
Early Growth ◽  
Nucleation And Growth ◽  
Pure Nickel ◽  
Different Temperatures ◽  
Total Fluence ◽  
Neutron Exposure ◽  
Growth Of Voids

Some information on the size and density of voids that develop in several high purity metals and alloys during irradiation with neutrons at elevated temperatures has been reported as a function of irradiation parameters. An area of particular interest is the nucleation and early growth stage of voids. It is the purpose of this paper to describe the microstructure in high purity nickel after irradiation to a very low but constant neutron exposure at three different temperatures.Annealed specimens of 99-997% pure nickel in the form of foils 75μ thick were irradiated in a capsule to a total fluence of 2.2 × 1019 n/cm2 (E > 1.0 MeV). The capsule consisted of three temperature zones maintained by heaters and monitored by thermocouples at 350, 400, and 450°C, respectively. The temperature was automatically dropped to 60°C while the reactor was down.

Continuous hydrogenolysis of acetal-stabilized lignin in flow

2021 ◽  
Author(s):  
Wu Lan ◽  
Yuan Peng Du ◽  
Songlan Sun ◽  
Jean Behaghel de Bueren ◽  
Florent Héroguel ◽  
...  
Keyword(s):  
Steady State ◽  
Challenges And Opportunities

We performed a steady state high-yielding depolymerization of soluble acetal-stabilized lignin in flow, which offered a window into challenges and opportunities that will be faced when continuously processing this feedstock.

Network reconstruction based on steady-state data

2008 ◽  
Vol 45 ◽  
pp. 161-176 ◽  
Author(s):  
Eduardo D. Sontag
Keyword(s):  
Steady State ◽  
Reverse Engineering ◽  
Theoretical Method ◽  
Network Reconstruction ◽  
Quasi Steady State ◽  
State Data

This paper discusses a theoretical method for the “reverse engineering” of networks based solely on steady-state (and quasi-steady-state) data.

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