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1

Fully stressed head of a pressure vessel  

Microsoft Academic Search

This work is devoted to a head of a vessel charged with internal uniform pressure. The analysis is aimed at finding a shape of the head that ensures its full charge with stresses. In a classical torispherical or ellipsoidal head the region of its joint with the cylindrical shell is loaded with shear force and bending moment as a result

K. Magnucki; J. Lewi?ski

2000-01-01

2

Stress analysis and evaluation of a rectangular pressure vessel  

NASA Astrophysics Data System (ADS)

This study addresses structural analysis and evaluation of an abnormal rectangular pressure vessel, designed to house equipment for drilling and collecting samples from Hanford radioactive waste storage tanks. It had to be qualified according to ASME boiler and pressure vessel code, section 8; however, it had the cover plate bolted along the long face, a configuration not addressed by the code. Finite element method was used to calculate stresses resulting from internal pressure; these stresses were then used to evaluate and qualify the vessel. Fatigue is not a concern; thus, it can be built according to section 8, division 1 instead of division 2. Stress analysis was checked against the code. A stayed plate was added to stiffen the long side of the vessel.

Rezvani, M. A.; Ziada, H. H.; Shurrab, M. S.

1992-10-01

3

Residual Stress Measurements of Explosively Clad Cylindrical Pressure Vessels  

SciTech Connect

Tantalum refractory liners were explosively clad into cylindrical pressure vessels, some of which had been previously autofrettaged. Using explosive cladding, the refractory liner formed a metallurgical bond with the steel of the pressure vessel at a cost of induced strain. Two techniques were employed to determine the residual stress state of the clad steel cylinders: neutron diffraction and mechanical slitting. Neutron diffraction is typically nondestructive; however, due to attenuation along the beam path, the cylinders had to be sectioned into rings that were nominally 25 mm thick. Slitting is a destructive method, requiring the sectioning of the cylindrical samples. Both techniques provided triaxial stress data and useful information on the effects of explosive cladding. The stress profiles in the hoop and radial directions were similar for an autofrettaged, nonclad vessel and a clad, nonautofrettaged vessel. The stress profiles in the axial direction appeared to be different. Further, the data suggested that residual stresses from the autofrettage and explosive cladding processes were not additive, in part due to evidence of reverse yielding. The residual stress data are presented, compared and discussed.

Taylor, Douglas J [TPL, Inc; Watkins, Thomas R [ORNL; Hubbard, Camden R [ORNL; Hill, M. R. [Hill Engineering; Meith, W. A. [Hill Engineering

2012-01-01

4

Stress Concentration Factors of Various Adjacent Holes Configurations in a Spherical Pressure Vessel  

Microsoft Academic Search

The analysis of stress concentration factor (SCF) of adjacent holes in a spherical pressure vessel can be approached by considering a thin plate undergoing hydrostatic stresses. This work adopts the approach to investigate the SCF of various adjacent holes configurations in a spherical pressure vessel using finite element analysis. The von Mises stress is considered to determine the SCF. Various

Kh. Fuad; R. A. Siregar; Ch. Rangkuti; B. Ariwahjoedi; M. Firdaus

5

Minimization of stress concentration factor in cylindrical pressure vessels with ellipsoidal heads  

Microsoft Academic Search

The paper presents the problem of stress concentration in a cylindrical pressure vessel with ellipsoidal heads subject to internal pressure. At the line, where the ellipsoidal head is adjacent to the circular cylindrical shell, a shear force and bending moment occur, disturbing the membrane stress state in the vessel. The degree of stress concentration depends on the ratio of thicknesses

K Magnucki; W Szyc; J Lewi?ski

2002-01-01

6

The inclusion of weld residual stress in fracture margin assessments of embrittled nuclear reactor pressure vessels  

SciTech Connect

Analyses were performed to determine the impact of weld residual stresses in a reactor pressure vessel (RPV) on (1) the generation of pressure temperature (P-T) curves required for maintaining specified fracture prevention margins during nuclear plant startup and shutdown, and (2) the conditional probability of vessel failure due to pressurized thermal shock (PTS) loading. The through wall residual stress distribution in an axially oriented weld was derived using measurements taken from a shell segment of a canceled RPV and finite element thermal stress analyses. The P-T curve derived from the best estimate load analysis and a t / 8 deep flaw, based on K{sub Ic}, was less limiting than the one derived from the current methodology prescribed in the ASME Boiler and Pressure Vessel Code. The inclusion of the weld residual stresses increased the conditional probability of cleavage fracture due to PTS loading by a factor ranging from 2 to 4.

Dickson, T.L.; Bass, B.R.; McAfee, W.J.

1998-01-01

7

Stress analysis and evaluation of a rectangular pressure vessel. [For equipment for sampling Hanford tank radwaste  

SciTech Connect

This study addresses structural analysis and evaluation of an abnormal rectangular pressure vessel, designed to house equipment for drilling and collecting samples from Hanford radioactive waste storage tanks. It had to be qualified according to ASME boiler and pressure vessel code, Section VIII; however, it had the cover plate bolted along the long face, a configuration not addressed by the code. Finite element method was used to calculate stresses resulting from internal pressure; these stresses were then used to evaluate and qualify the vessel. Fatigue is not a concern; thus, it can be built according to Section VIII, Division I instead of Division 2. Stress analysis was checked against the code. A stayed plate was added to stiffen the long side of the vessel.

Rezvani, M.A.; Ziada, H.H. (Westinghouse Hanford Co., Richland, WA (United States)); Shurrab, M.S. (Westinghouse Savannah River Co., Aiken, SC (United States))

1992-10-01

8

NDE methodologies for characterisation of defects, stresses and microstructures in pressure vessels and pipes  

Microsoft Academic Search

Assessment of integrity of pressure vessels and pipes is becoming increasingly important for both economic and safety reasons. Presence of harmful defects, tensile residual stresses and unacceptable microstructures may affect the integrity of any component and therefore assessment of defects, residual stresses and microstructures is essential. Many non-destructive testing techniques are employed for high sensitive detection and complete characterisation of

Baldev Raj; T. Jayakumar

1997-01-01

9

Study of stress concentration at the round corners of flat heads in pressure vessels subjected to internal pressure  

Microsoft Academic Search

Results from finite element analysis were used to show that the stress index K{sub Ï} and the nondimensionalized highly stressed hub length k{sub h} of a flat head with a round corner in a pressure vessel subjected to internal pressure are functions of three dimensionless parameters: λ â¡ h\\/â(dt), η â¡ t\\/d, and ρ â¡ r\\/t. Approximate formulas for estimating

H. Chen; J. Jin; J. Yu

1996-01-01

10

Stress Analysis of Conical Shell Skirt Support for High Pressure Vessel Using Finite Element Method  

Microsoft Academic Search

Pressure vessel is a closed cylindrical vessel for storing gaseous, liquids or solid products. The stored medium is at a particular pressure and temperature. The cylindrical vessel is closed at both ends by means of dished head, which may be hemispherical, ellipsoidal. The pressure vessels may be horizontal or vertical. The supporting system of this vertical vessel plays an important

K. Tamil Mannan; Rakesh Saxena; R. Murugavel; P. L. Sah

2009-01-01

11

Measurements of stress-concentration factors in the external fillets of a cylindrical pressure vessel  

Microsoft Academic Search

Strain-gage measurements were made in and near the external circumferential fillets of a circular cylindrical pressure vessel with stepped wall thicknesses. Six combinations of fillet radii and wall thicknesses were tested. Data were obtained along the inside and outside surfaces of four equally spaced longitudinal sections. Discrete strain-gage measurements in the high-straingradient areas were transformed to continuous stress distributions. This

J. H. Heifetz; I. Berman

1967-01-01

12

PRESTRESSED CONCRETE PRESSURE VESSELS  

Microsoft Academic Search

The pros and cons of using prestressed concrete pressure vessels, based ; on observations of model tests, for the next British nuclear power station are ; reviewed. The characteristics, present development, and design methods are ; considered. The results indicate that the prestressed concrete pressure vessel ; is more practicable, safe, and economical than the steel vessel. (N.W.R.)

S. Gill; I. W. Hannah

1962-01-01

13

Dual shell pressure balanced vessel  

DOEpatents

A dual-wall pressure balanced vessel for processing high viscosity slurries at high temperatures and pressures having an outer pressure vessel and an inner vessel with an annular space between the vessels pressurized at a pressure slightly less than or equivalent to the pressure within the inner vessel.

Fassbender, Alexander G. (West Richland, WA)

1992-01-01

14

Pressurized Vessel Slurry Pumping  

SciTech Connect

This report summarizes testing of an alternate ''pressurized vessel slurry pumping'' apparatus. The principle is similar to rural domestic water systems and ''acid eggs'' used in chemical laboratories in that material is extruded by displacement with compressed air.

Pound, C.R.

2001-09-17

15

Sapphire tube pressure vessel  

SciTech Connect

A pressure vessel is provided for observing corrosive fluids at high temperatures and pressures. A transparent Teflon bag contains the corrosive fluid and provides an inert barrier. The Teflon bag is placed within a sapphire tube, which forms a pressure boundary. The tube is received within a pipe including a viewing window. The combination of the Teflon bag, sapphire tube and pipe provides a strong and inert pressure vessel. In an alternative embodiment, tie rods connect together compression fittings at opposite ends of the sapphire tube.

Outwater, J.O.

2000-05-23

16

Creep deformations and stresses in thick-walled cylindrical vessels of functionally graded materials subjected to internal pressure  

Microsoft Academic Search

Steady-state creep of thick-walled cylindrical vessels made of functionally graded materials subjected to internal pressure is investigated in this paper. Taking material parameters involved in Norton’s law to be the functions of the radial coordinate, a simple and accurate method is developed from the strain rate–stress relations, Norton’s law, deformation compatibility condition and equilibrium equation of axisymmetric, plane strain problems.

L. H. You; H. Ou; Z. Y. Zheng

2007-01-01

17

Finite Element Analysis of Pressure Vessels  

Microsoft Academic Search

Pressure vessels are a commonly used device in marine engineering. Until recently the primary analysis method had been hand calculations and empirical curves. New computer advances have made finite element analysis (FEA) a practical tool in the study of pressure vessels, especially in determining stresses in local areas such as penetrations, O-ring grooves and other areas difficult to analyze by

David Heckman

1998-01-01

18

High pressure storage vessel  

DOEpatents

Disclosed herein is a composite pressure vessel with a liner having a polar boss and a blind boss a shell is formed around the liner via one or more filament wrappings continuously disposed around at least a substantial portion of the liner assembly combined the liner and filament wrapping have a support profile. To reduce susceptible to rupture a locally disposed filament fiber is added.

Liu, Qiang

2013-08-27

19

Stress concentration factors for an internally pressurized circular vessel containing a radial U-notch  

Microsoft Academic Search

This paper evaluates the stress concentration factors for an internally pressurized cylinder containing a radial U-notch along its length. This work studies the cases where the external to internal radius ratio (?) is equal to 1.26, 1.52, 2.00, and 3.00 and the notch radius to internal radius ratio (?) is fixed and equal to 0.026. The U-notch depth varies from

E. A. de Carvalho

2005-01-01

20

Shape optimization of a perforated pressure vessel cover under linearized stress constraints  

Microsoft Academic Search

One of the general methods to evaluate a failure condition is to compare a maximum stress with an allowable stress. A failure condition for a stress is usually applied to a concerned point rather than a concerned section. In an optimization procedure, these stress conditions are applied as constraints. But the ASME code that prescribes its general rules upon the

Woo-Seok Choi; Tae-Wan Kim; Ki-Seog Seo

2008-01-01

21

Life prediction of pressure vessel nozzles  

Microsoft Academic Search

When the material yields local stress and strain behaviour changes, especially if there is a notch, determination of the local strain value can be difficult. Therefore it is not easy to predict the life of mechanical components in the low-cycle region. In the present work pressure vessels are considered and fatigue tests carried out. The most stressed zones, which are

M. Giglio; L. Vergani

1995-01-01

22

STRESS CONCENTRATION IN HEAVY-WALLED CYLINDRICAL PRESSURE VESSELS. EFFECT OF ELLIPTIC AND CIRCULAR SIDE HOLES  

Microsoft Academic Search

This work was done to establish realistic stress concentration factors ; for side holes in cylinders. Contrary to intuitive reasoning, the ; circumferential stress at the cylinder bore-circular side hole interface is ; intensified by a factor less than 3.0. These factors for both elliptic and ; circular side holes approach a maximum with increasing ratio of outside to inside

J. H. Faupel; D. B. Harris

1957-01-01

23

Image-based biomechanical modeling of aortic wall stress and vessel deformation: response to pulsatile arterial pressure simulations  

NASA Astrophysics Data System (ADS)

Image-based modeling of cardiovascular biomechanics may be very helpful for patients with aortic aneurysms to predict the risk of rupture and evaluate the necessity of a surgical intervention. In order to generate a reliable support it is necessary to develop exact patient-specific models that simulate biomechanical parameters and provide individual structural analysis of the state of fatigue and characterize this to the potential of rupture of the aortic wall. The patient-specific geometry used here originates from a CT scan of an Abdominal Aortic Aneurysm (AAA). The computations are based on the Finite Element Method (FEM) and simulate the wall stress distribution and the vessel deformation. The wall transient boundary conditions are based on real time-dependent pressure simulations obtained from a previous computational fluid dynamics study. The physiological wall material properties consider a nonlinear hyperelastic constitutive model, based on realistic ex-vivo analysis of the aneurismal arterial tissue. The results showed complex deformation and stress distribution on the AAA wall. The maximum stresses occurred at the systole and are found around the aneurismal bulge in regions close to inflection points. Biomechanical modeling based on medical images and coupled with patient-specific hemodynamics allows analysing and quantifying the effects of dilatation of the arterial wall due to the pulsatile aortic pressure. It provides a physical and realistic insight into the wall mechanics and enables predictive simulations of AAA growth and assessment of rupture. Further development integrating endovascular models would help evaluating non-invasively individual treatment strategies for optimal placement and improved device design.

Hazer, Dilana; Bauer, Miriam; Unterhinninghofen, Roland; Dillmann, Rüdiger; Richter, Götz-M.

2008-04-01

24

Thermionic fuel element pressure vessel  

SciTech Connect

This patent describes a thermionic convertor core. It comprises an array of thermionic fuel elements wherein each fuel element comprises: a nuclear fuel heat source; an emitter thermally coupled to and generally surrounding the heat source; a collector in a spaced relationship from and generally surrounding the emitter; and a pressure vessel generally surrounding the collector; and, wherein an axial cross-section of each pressure vessel surrounding a collector has generally the shape of a polygon and the pressure vessels are arranged in physical contact polygon side to polygon side.

Kennel, E.B.; Perry, M.S.; Leland, J.E.

1991-08-13

25

Isotropic and Anisotropic Creep Characteristics of Thick-Walled Pressure Vessels under Elastic/Plastic Stress.  

National Technical Information Service (NTIS)

By using the theory of finite deformations the isochoric creep behaviour of thick-walled high-pressure containers (multi-layer containers) which have been deformed elastoplastically at the beginning of creep due to internal and external pressure is descri...

D. Knoerzer

1985-01-01

26

46 CFR 169.249 - Pressure vessels.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Pressure vessels. 169.249 Section...SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Inspection and Certification... Inspections § 169.249 Pressure vessels. Pressure...

2009-10-01

27

46 CFR 169.249 - Pressure vessels.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Pressure vessels. 169.249 Section...SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Inspection and Certification... Inspections § 169.249 Pressure vessels. Pressure...

2012-10-01

28

46 CFR 169.249 - Pressure vessels.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Pressure vessels. 169.249 Section...SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Inspection and Certification... Inspections § 169.249 Pressure vessels. Pressure...

2011-10-01

29

46 CFR 169.249 - Pressure vessels.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Pressure vessels. 169.249 Section...SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Inspection and Certification... Inspections § 169.249 Pressure vessels. Pressure...

2010-10-01

30

Level indicator for pressure vessels  

DOEpatents

A liquid-level monitor for tracking the level of a coal slurry in a high-pressure vessel including a toroidal-shaped float with magnetically permeable bands thereon disposed within the vessel, two pairs of magnetic-field generators and detectors disposed outside the vessel adjacent the top and bottom thereof and magnetically coupled to the magnetically permeable bands on the float, and signal-processing circuitry for combining signals from the top and bottom detectors for generating a monotonically increasing analog control signal which is a function of liquid level. The control signal may be utilized to operate high-pressure control valves associated with processes in which the high-pressure vessel is used.

Not Available

1982-04-28

31

PWR pressure vessel integrity during overcooling accidents  

SciTech Connect

Pressurized water reactors are susceptible to certain types of hypothetical accidents that under some circumstances, including operation of the reactor beyond a critical time in its life, could result in failure of the pressure vessel as a result of propagation of crack-like defects in the vessel wall. The accidents of concern are those that result in thermal shock to the vessel while the vessel is subjected to internal pressure. Such accidents, referred to as pressurized thermal shock or overcooling accidents (OCA), include a steamline break, small-break LOCA, turbine trip followed by stuck-open bypass valves, the 1978 Rancho Seco and the TMI accidents and many other postulated and actual accidents. The source of cold water for the thermal shock is either emergency core coolant or the normal primary-system coolant. ORNL performed fracture-mechanics calculations for a steamline break in 1978 and for a turbine-trip case in 1980 and concluded on the basis of the results that many more such calculations would be required. To meet the expected demand in a realistic way a computer code, OCA-I, was developed that accepts primary-system temperature and pressure transients as input and then performs one-dimensional thermal and stress analyses for the wall and a corresponding fracture-mechanics analysis for a long axial flaw. The code is briefly described, and its use in both generic and specific plant analyses is discussed.

Cheverton, R.D.

1981-01-01

32

Burst failure load of composite pressure vessels  

Microsoft Academic Search

In this study, optimal angle-ply orientations of symmetric and antisymmetric [?\\/??]s shells designed for maximum burst pressure were examined. Burst pressure of filament wound composite pressure vessels under alternating pure internal pressure was investigated. The study deals with the influences of temperature and winding angle on filament wound composite pressure vessels. Finite element method and experimental approaches were employed to

Aziz Onder; Onur Sayman; Tolga Dogan; Necmettin Tarakcioglu

2009-01-01

33

Development of Residual Stress Improvement for Nuclear Pressure Vessel Instrumentation Nozzle Weld Joint (P-43+P-8) by Means of Induction Heating  

SciTech Connect

As a counter measurement of intergranular stress corrosion cracking (IGSCC) in boiling water reactors, the induction heating stress improvement (IHSI) has been developed as a method to improve the stress factor, especially residual stresses in affected areas of pipe joint welds. In this method, a pipe is heated from the outside by an induction coil and cooled from the inside with water simultaneously. By thermal stresses to produce a temperature differential between the inner and outer pipe surfaces, the residual stress inside the pipe is improved compression. IHSI had been applied to weld joints of austenitic stainless steel pipes (P-8+P-8). However IHSI had not been applied to weld joints of nickel-chromium-iron alloy (P-43) and austenitic stainless steel (P-8). This weld joint (P-43+P-8) is used for instrumentation nozzles in nuclear power plants' reactor pressure vessels. Therefore for the purpose of applying IHSI to this one, we studied the following: Investigation of IHSI conditions (Essential Variables); Residual stresses after IHSI; Mechanical properties after IHSI. This paper explains that IHSI is sufficiently effective in improvement of the residual stresses for this weld joint (P-43+P-8), and that IHSI does not cause negative effects by results of mechanical properties, and IHSI is verified concerning applying it to this kind of weld joint. (authors)

Takuro Terajima; Takashi Hirano [Ishikawajima-Harima Heavy Industies Co., Ltd (Japan)

2006-07-01

34

Investigation on constraint effect of reactor pressure vessel under pressurized thermal shock  

Microsoft Academic Search

In recent years, the integrity of reactor pressure vessels (RPVs) under pressurized thermal shock (PTS) accident has been treated as one of the most critical issues. Under PTS condition, the combination of thermal stress due to a steep temperature gradient and mechanical stress due to internal pressure causes considerable tensile stress inside the RPV wall. As a result, cracks on

Jin-Su Kim; Jae-Boong Choi; Young-Jin Kim; Youn-Won Park

2003-01-01

35

Three-term Asymptotic Stress Field Expansion for Analysis of Surface Cracked Elbows in Nuclear Pressure Vessels  

NASA Astrophysics Data System (ADS)

Elbows with a shallow surface cracks in nuclear pressure pipes have been recognized as a major origin of potential catastrophic failures. Crack assessment is normally performed by using the J-integral approach. Although this one-parameter-based approach is useful to predict the ductile crack onset, it depends strongly on specimen geometry or constraint level. When a shallow crack exists (depth crack-to-thickness wall ratio less than 0.2) and/or a fully plastic condition develops around the crack, the J-integral alone does not describe completely the crack-tip stress field. In this paper, we report on the use of a three-term asymptotic expansion, referred to as the J- A 2 methodology, for modeling the elastic-plastic stress field around a three-dimensional shallow surface crack in an elbow subjected to internal pressure and out-of-plane bending. The material, an A 516 Gr. 70 steel, used in the nuclear industry, was modeled with a Ramberg-Osgood power law and flow theory of plasticity. A finite deformation theory was included to account for the highly nonlinear behavior around the crack tip. Numerical finite element results were used to calculate a second fracture parameter A 2 for the J- A 2 methodology. We found that the used three-term asymptotic expansion accurately describes the stress field around the considered three-dimensional shallow surface crack.

Labbe, Fernando

2007-04-01

36

LPT. EBOR reactor vessel in TAN 646. Pressure vessel head ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

LPT. EBOR reactor vessel in TAN 646. Pressure vessel head being installed in vault. Refueling port extension (right) and control rod nozzles (center). Camera facing northwest. Photographer: Comiskey. Date: January 20, 1965. INEEL negative no. 65-241 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

37

Nuclear reactor pressure vessel support system  

DOEpatents

A support system for nuclear reactor pressure vessels which can withstand all possible combinations of stresses caused by a postulated core disrupting accident during reactor operation. The nuclear reactor pressure vessel is provided with a flange around the upper periphery thereof, and the flange includes an annular vertical extension formed integral therewith. A support ring is positioned atop of the support ledge and the flange vertical extension, and is bolted to both members. The plug riser is secured to the flange vertical extension and to the top of a radially outwardly extension of the rotatable plug. This system eliminates one joint through which fluids contained in the vessel could escape by making the fluid flow path through the joint between the flange and the support ring follow the same path through which fluid could escape through the plug risers. In this manner, the sealing means to prohibit the escape of contained fluids through the plug risers can also prohibit the escape of contained fluid through the securing joint.

Sepelak, George R. (McMurray, PA)

1978-01-01

38

Expanded Fermilab pressure vessel directory program  

SciTech Connect

Several procedures have been written to manage the information pertaining to the vacuum tanks and pressure vessels for which the laboratory is responsible. These procedures have been named TANK1 for the vessels belonging to the Accelerator Division, TANK2 and TANK3 for the vessels belonging to the Research Division and to Technical Support respectively, and TANK4 for the vessels belonging to the Business Division. The operating procedures are otherwise identical in every respect.

Tanner, A.

1983-01-01

39

Reactor pressure vessel. Status report  

SciTech Connect

This report describes the issues raised as a result of the staffs review of Generic Letter (GL) 92-01, Revision 1, responses and plant-specific reactor pressure vessel (RPV) assessments and the actions taken or work in progress to address these issues. In addition, the report describes actions taken by the staff and the nuclear industry to develop a thermal annealing process for use at U.S. commercial nuclear power plants. This process is intended to be used as a means of mitigating the effects of neutron radiation on the fracture toughness of RPV materials. The Nuclear Regulatory Commission (NRC) issued GL 92-01, Revision 1, Supplement 1, to obtain information needed to assess compliance with regulatory requirements and licensee commitments regarding RPV integrity. GL 92-01, Revision 1, Supplement 1, was issued as a result of generic issues that were raised in the NRC staff`s reviews of licensee responses to GL 92-01, Revision 1, and plant-specific RPV evaluations. In particular, an integrated review of all data submitted in response to GL 92-01, Revision 1, indicated that licensees may not have considered all relevant data in their RPV assessments. This report is representative of submittals to and evaluations by the staff as of September 30, 1996. An update of this report will be issued at a later date.

Elliot, B.J.; Hackett, E.M.; Lee, A.D. [and others

1996-10-01

40

Lightweight bladder lined pressure vessels  

DOEpatents

A lightweight, low permeability liner for graphite epoxy composite compressed gas storage vessels. The liner is composed of polymers that may or may not be coated with a thin layer of a low permeability material, such as silver, gold, or aluminum, deposited on a thin polymeric layer or substrate which is formed into a closed bladder using torispherical or near torispherical end caps, with or without bosses therein, about which a high strength to weight material, such as graphite epoxy composite shell, is formed to withstand the storage pressure forces. The polymeric substrate may be laminated on one or both sides with additional layers of polymeric film. The liner may be formed to a desired configuration using a dissolvable mandrel or by inflation techniques and the edges of the film seamed by heat sealing. The liner may be utilized in most any type of gas storage system, and is particularly applicable for hydrogen, gas mixtures, and oxygen used for vehicles, fuel cells or regenerative fuel cell applications, high altitude solar powered aircraft, hybrid energy storage/propulsion systems, and lunar/Mars space applications, and other applications requiring high cycle life.

Mitlitsky, Fred (1125 Canton Ave., Livermore, CA 94550); Myers, Blake (4650 Almond Cir., Livermore, CA 94550); Magnotta, Frank (1206 Bacon Way, Lafayette, CA 94549)

1998-01-01

41

Lightweight bladder lined pressure vessels  

DOEpatents

A lightweight, low permeability liner is described for graphite epoxy composite compressed gas storage vessels. The liner is composed of polymers that may or may not be coated with a thin layer of a low permeability material, such as silver, gold, or aluminum, deposited on a thin polymeric layer or substrate which is formed into a closed bladder using tori spherical or near tori spherical end caps, with or without bosses therein, about which a high strength to weight material, such as graphite epoxy composite shell, is formed to withstand the storage pressure forces. The polymeric substrate may be laminated on one or both sides with additional layers of polymeric film. The liner may be formed to a desired configuration using a dissolvable mandrel or by inflation techniques and the edges of the film sealed by heat sealing. The liner may be utilized in most any type of gas storage system, and is particularly applicable for hydrogen, gas mixtures, and oxygen used for vehicles, fuel cells or regenerative fuel cell applications, high altitude solar powered aircraft, hybrid energy storage/propulsion systems, and lunar/Mars space applications, and other applications requiring high cycle life. 19 figs.

Mitlitsky, F.; Myers, B.; Magnotta, F.

1998-08-25

42

Thick-wall Kevlar 49/Epoxy pressure vessels  

SciTech Connect

The feasibility of thick-wall composite vessels for very high pressure applications is demonstrated. Prototype vessels, in both spherical and cylindrical geometries, were designed, fabricated and burst tested. It is shown that experimental burst pressures are in excellent agreement with predicted values for burst pressures up to 60 ksi. Each unit consisted of a thin, seamless, copper liner with stainless steel fill stems and a filament-wound Kevlar 49/epoxy outer shell. Analysis of vessel performance accounted for liner thickness and yield strengths, composite thickness, mechanical properties and fiber volume fraction, and stress concentrations caused by the fill stem. Spherical vessels of three different sizes (inside diameters of 2.15 inches, 4.0 inches and 5.3 inches) with either 30 ksi or 60 ksi design burst pressure are discussed. Also, cylindrical vessels with identical liners but of two different composite thicknesses are described. These vessels achieved 50 ksi and 57 ksi burst pressures, respectively. In addition to the design considerations alluded to throughout the paper, the stress state in a thin metal liner during cyclic loading and the life prediction of composite vessels under sustained loading are discussed.

Guess, T.R.

1984-01-01

43

In-service pressure vessel inspections  

NASA Astrophysics Data System (ADS)

Eliminate any doubt that the vessel condition is suitable for continued operation through a planned inspection program that can mitigate or avoid failure of a pressure vessel due to corrosion or erosion. Proper inspection and documentation help you in identifying the problem and confirming the actual thickness leading to properly correcting deficiencies. Proper inspection is the antidote for any inspection program. Vessel life can be extended, risk can be minimized and unscheduled downtime can be prevented by implementing and managing your inspection program. A successful program includes maintaining accurate records, conducting inspections in regular intervals, and taking proper action on deficiencies. Therefore, you will know what you have and the condition of your equipment. Pressure vessel inspections can be classified into two general categories: surface inspection and volumetric inspection. Surface techniques for vessels include two of the commonest types: dye-penetrant and magnetic particle testing. Board qualified inspectors are required to perform these two tests. Volumetric techniques for vessels include three common types: ultrasonic testing, eddy current testing, and radiography. At Abbott the use of advanced NDE (non destructive examination) techniques, ultrasonic b-scan, has provided us with the proper tools to obtain the above objectives. We have been applying ultrasonic b-scan utilizing a pulse echo pitch catch technique to provide us with essential data on each of our pressure vessels. This reduces equipment downtime because the nondestructive examination usually takes place while our vessels are in service. As inspections take place we are able to view a real time image of the defective discontinuities on a video monitor. This ultrasonic b-scan technique is allowing us to perform fast accurate examinations covering up to 96% of the surface area of each pressure vessel.

Fields, Marvin

1998-03-01

44

Liquid Nitrogen Subcooler Pressure Vessel Engineering Note  

SciTech Connect

The normal operating pressure of this dewar is expected to be less than 15 psig. This vessel is open to atmospheric pressure thru a non-isolatable vent line. The backpressure in the vent line was calculated to be less than 1.5 psig at maximum anticipated flow rates.

Rucinski, R.; /Fermilab

1997-04-24

45

Vehicular storage of hydrogen in insulated pressure vessels  

Microsoft Academic Search

This paper describes an alternative technology for storing hydrogen fuel onboard vehicles. Insulated pressure vessels are cryogenic capable vessels that can accept cryogenic liquid hydrogen, cryogenic compressed gas or compressed hydrogen gas at ambient temperature. Insulated pressure vessels offer advantages over conventional storage approaches. Insulated pressure vessels are more compact and require less carbon fiber than compressed hydrogen vessels. They

Salvador M. Aceves; Gene D. Berry; Joel Martinez-Frias; Francisco Espinosa-Loza

2006-01-01

46

Fatigue design of an autofrettaged thick-walled pressure vessel using CAE techniques  

Microsoft Academic Search

In order to increase the fatigue life of an autofrettaged thick-walled pressure vessel, computer aided engineering techniques were applied. The fatigue life increase of the external grooved pressure vessel was achieved by relieving the high-stress concentration at the external groove. Shape optimization of the external groove incorporating the finite element stress analysis was performed, resulting in an optimized double grooved

S. K. Koh; S. I. Lee; S. H. Chung; K. Y. Lee

1997-01-01

47

Finite Element Analysis for a Two-Layered Spherical High-Pressure Vessel  

Microsoft Academic Search

Stress analysis is of importance for security assessment of pressure vessels in the design and manufacture processes. This paper presents a stress analysis for a two-layered spherical high-pressure vessel of special steel. Firstly, the finite element model was built by the software ANSYS. In order to get an acceptable analysis precision, the proper mesh density distribution was obtained by the

Yu Shaorong; Yin Yihui; Xu Bing; Tan Yun; Sun Ying

2010-01-01

48

Beryllium pressure vessels for creep tests in magnetic fusion energy  

SciTech Connect

Beryllium has interesting applications in magnetic fusion experimental machines and future power-producing fusion reactors. Chief among the properties of beryllium that make these applications possible is its ability to act as a neutron multiplier, thereby increasing the tritium breeding ability of energy conversion blankets. Another property, the behavior of beryllium in a 14-MeV neutron environment, has not been fully investigated, nor has the creep behavior of beryllium been studied in an energetic neutron flux at thermodynamically interesting temperatures. This small beryllium pressure vessel could be charged with gas to test pressures around 3, 000 psi to produce stress in the metal of 15,000 to 20,000 psi. Such stress levels are typical of those that might be reached in fusion blanket applications of beryllium. After contacting R. Powell at HEDL about including some of the pressure vessels in future test programs, we sent one sample pressure vessel with a pressurizing tube attached (Fig. 1) for burst tests so the quality of the diffusion bond joints could be evaluated. The gas used was helium. Unfortunately, budget restrictions did not permit us to proceed in the creep test program. The purpose of this engineering note is to document the lessons learned to date, including photographs of the test pressure vessel that show the tooling necessary to satisfactorily produce the diffusion bonds. This document can serve as a starting point for those engineers who resume this task when funds become available.

Neef, W.S.

1990-07-20

49

Tougher steels improve pressure vessel performance  

SciTech Connect

Safe operation of pressure vessels requires conservative design and construction practices, and use of materials having adequate safety margins. Pressure vessel safety is of particular concern to petroleum refiners, coal converters, and others in the hydrocarbon processing industries, where high temperatures and hydrogen-containing environments put an added strain on equipment. Because of these concerns, designers and fabricators have imposed increasingly stringent specifications on ASTM A 387 steel plate, which is widely used for pressure vessel applications. One requirement that has had a major impact on the evolution of A 387 steels is the need for improved toughness. As customer requirements have become more stringent, steelmakers have responded with methods that yield lower sulfur content and help control other chemical elements. These efforts have resulted in some significant benefits, including improved toughness and reduced susceptibility to temper embrittlement. Yet, at the same time, producers are realizing they will soon have reached the limit of capability for further improving A 387 steels.

Wilson, A.D. (Lukens Steel Co., Coatesville, PA (United States))

1993-04-01

50

Tests of torispherical pressure vessel heads convex to pressure  

Microsoft Academic Search

Eighteen pressure vessel heads having nine different geometries and made from two different steels were subjected to monotonically increasing external pressure until collapse occurred. Deflection of the crown and strains in the most highly strained regions of the concave side of the heads were recorded as functions of pressure. All heads underwent permanent deformations. Four modes of failure were observed:

C. E. Washington; R. J. Clifton; B. W. Costerus

1977-01-01

51

Boiling water reactor pressure vessel life extension  

SciTech Connect

The reactor pressure vessel (RPV) is one of the components which is critical to a potential nuclear power plant life extension. Previous EPRI research has indicated that plant life extension may be feasible, even assuming wholesale replacement of a pressurized water reactor RPV. This paper describes the results of a service life extension study for an operating boiling water reactor (BWR) vessel. The study was conducted under a BWR pilot plant program sponsored in part by EPRI and the Department of Energy. The purpose of the investigation was to identify the probable RPV life limiting effects, and the potential for extending life.

Gregor, F.E.; Hagan, K.A.

1986-04-01

52

Pressurized wet digestion in open vessels.  

PubMed

The High Pressure Asher (HPA-S) was adapted with a Teflon liner for pressurized wet digestion in open vessels. The autoclave was partly filled with water containing 5% (vol/vol) hydrogen peroxide. The digestion vessels dipped partly into the water or were arranged on top of the water by means of a special rack made of titanium or PTFE-coated stainless steel. The HPA-S was closed and pressurized with nitrogen up to 100 bars. The maximum digestion temperature was 250 degrees C for PFA vessels and 270 degrees C for quartz vessels. Digestion vessels made of quartz or PFA-Teflon with volumes between 1.5 mL (auto sampler cups) and 50 mL were tested. The maximum sample amount for quartz vessels was 0.5-1.5 g and for PFA vessels 0.2-0.5 g, depending on the material. Higher sample intake may lead to fast reactions with losses of digestion solution. The samples were digested with 5 mL HNO(3) or with 2 mL HNO(3)+6 mL H(2)O+2 mL H(2)O(2). The total digestion time was 90-120 min and 30 min for cooling down to room temperature. Auto sampler cups made of PFA were used as digestion vessels for GFAAS. Sample material (50 mg) was digested with 0.2 mL HNO(3)+0.5 mL H(2)O+0.2 mL H(2)O(2). The analytical data of nine certified reference materials are also within the confidential intervals for volatile elements like mercury, selenium and arsenic. No cross contamination between the digestion vessels could be observed. Due to the high gas pressure, the diffusion rate of volatile species is low and losses of elements by volatilisation could be observed only with diluted nitric acid and vessels with large cross section. In addition, cocoa, walnuts, nicotinic acid, pumpkin seeds, lubrication oil, straw, polyethylene and coal were digested and the TOC values measured. The residual carbon content came to 0.2-10% depending on the sample matrix and amount. PMID:12802569

Maichin, B; Zischka, M; Knapp, G

2003-06-11

53

Guidelines for pressure vessel safety assessment  

NASA Astrophysics Data System (ADS)

A technical overview and information on metallic pressure containment vessels and tanks is given. The intent is to provide Occupational Safety and Health Administration (OSHA) personnel and other persons with information to assist in the evaluation of the safety of operating pressure vessels and low pressure storage tanks. The scope is limited to general industrial application vessels and tanks constructed of carbon or low alloy steels and used at temperatures between -75 and 315 C (-100 and 600 F). Information on design codes, materials, fabrication processes, inspection and testing applicable to the vessels and tanks are presented. The majority of the vessels and tanks are made to the rules and requirements of ASME Code Section VIII or API Standard 620. The causes of deterioration and damage in operation are described and methods and capabilities of detecting serious damage and cracking are discussed. Guidelines and recommendations formulated by various groups to inspect for the damages being found and to mitigate the causes and effects of the problems are presented.

Yukawa, S.

1990-04-01

54

Annealing of nuclear reactor pressure vessels  

Microsoft Academic Search

The neutron embrittlement that occurs in the beltline of reactor pressure vessels (RPV) can be managed by various techniques such as fuel management, but only thermal annealing can reverse the effects and result in a restoration of RPV beltline material toughness. The US Nuclear Regulatory Commission has recently revised the Code of Federal Regulations to include the use of thermal

M. G Vassilaros; M. E Mayfield; K. R Wichman

1998-01-01

55

Influence of mosaic patterns on the structural integrity of filament wound composite pressure vessels  

Microsoft Academic Search

Purpose – Filament wound pressure vessels have a characteristic pattern observed in their helical layers. These are mosaic-shaped patterns and affect the layer structural behavior. The present research aims to focus on the influence of mosaic patterns on stress-strain field and structural design of thin-walled internally pressurized filament wound pressure vessel. The widely used stress analysis procedures and the commercially

Haris Hameed Mian; Hammad Rahman

2011-01-01

56

Pressure vessel burst test program - Progress paper No. 4  

NASA Astrophysics Data System (ADS)

A status report is presented for a program studying the characteristics of the blast waves and fragmentation caused by ruptured gas-filled pressure vessels. Experimental data trends have been derived from 14 burst pressure vessels. Attention is given to energy release in bursting, blast wave and fragmentation behavior, height of burst effects, fragment velocity vs vessel pressure, and comparative blast effects for spherical/composite vs cylindrical/steel pressure vessels.

Cain, Maurice R.; Sharp, Douglas E.

1993-06-01

57

Critical crack depth diagram of reactor vessel for pressurized thermal shock  

Microsoft Academic Search

During the operation of a pressurized water reactor, a certain type of transients could induce rapid cooldown of the reactor pressure vessel (RPV) with relatively high or increasing system pressure. This induces a high tensile stress at the inner surface of the RPV, which is called the pressurized thermal shock (PTS). The structural integrity of the RPV during PTS should

Myung Jo Jhung; Young Hwan Choi

2009-01-01

58

Pool critical assembly pressure vessel facility benchmark  

SciTech Connect

This pool critical assembly (PCA) pressure vessel wall facility benchmark (PCA benchmark) is described and analyzed in this report. Analysis of the PCA benchmark can be used for partial fulfillment of the requirements for the qualification of the methodology for pressure vessel neutron fluence calculations, as required by the US Nuclear Regulatory Commission regulatory guide DG-1053. Section 1 of this report describes the PCA benchmark and provides all data necessary for the benchmark analysis. The measured quantities, to be compared with the calculated values, are the equivalent fission fluxes. In Section 2 the analysis of the PCA benchmark is described. Calculations with the computer code DORT, based on the discrete-ordinates method, were performed for three ENDF/B-VI-based multigroup libraries: BUGLE-93, SAILOR-95, and BUGLE-96. An excellent agreement of the calculated (C) and measures (M) equivalent fission fluxes was obtained. The arithmetic average C/M for all the dosimeters (total of 31) was 0.93 {+-} 0.03 and 0.92 {+-} 0.03 for the SAILOR-95 and BUGLE-96 libraries, respectively. The average C/M ratio, obtained with the BUGLE-93 library, for the 28 measurements was 0.93 {+-} 0.03 (the neptunium measurements in the water and air regions were overpredicted and excluded from the average). No systematic decrease in the C/M ratios with increasing distance from the core was observed for any of the libraries used.

Remec, I.; Kam, F.B.K. [Oak Ridge National Lab., TN (United States)

1997-07-01

59

46 CFR 61.10-5 - Pressure vessels in service.  

Code of Federal Regulations, 2011 CFR

...Guard Symbol. (f) Compressed gas or hazardous liquid...vessel tests. Cargo tanks of pressure vessel configuration...containing liquefied, compressed gases or hazardous...chapter. (g) Bulk storage tanks. Each bulk...

2011-10-01

60

High pressure magnetic resonance imaging with metallic vessels.  

PubMed

High pressure measurements in most scientific fields rely on metal vessels given the superior tensile strength of metals. We introduce high pressure magnetic resonance imaging (MRI) measurements with metallic vessels. The developed MRI compatible metallic pressure vessel concept is very general in application. Macroscopic physical systems are now amenable to spatially resolved nuclear magnetic resonance (NMR) study at variable pressure and temperature. Metallic pressure vessels not only provide inherently high tensile strengths and efficient temperature control, they also permit optimization of the MRI RF probe sensitivity. An MRI compatible pressure vessel is demonstrated with a rock core holder fabricated using non-magnetic stainless steel. Water flooding through a porous rock under pressure is shown as an example of its applications. High pressure NMR spectroscopy plays an indispensable role in several science fields. This work will open new vistas of study for high pressure material science MRI and MR. PMID:21962929

Han, Hui; Ouellette, Matthew; MacMillan, Bryce; Goora, Frederic; MacGregor, Rodney; Green, Derrick; Balcom, Bruce J

2011-09-10

61

Hydroide Storage Vessel wall stress measurements  

SciTech Connect

Holographic Interferometry and strain gauge measurements were used to determine whether a prototype Hydride Storage Vessel (HSV) swelled while it was loaded in eleven stages with hydrogen. Bed swelling is inferred from deformation of the surface of the HSV. No swelling was detected, even after saturating the hydride material inside the HSV. The large chunky morphology of the titanium is likely responsible for the lack of wall stress. This morphology also implies that decay helium that remains in the titanium hydride (that is, helium that is not released as gas to the free volume) should not cause significant wall stresses when the HSV is used for long-term tritium storage. Holographic interferometry proved to be an extremely sensitive technique to measure swelling, having a detection limit of about 3 microns surface displacement.

Clark, E.A. [Westinghouse Savannah River Company, AIKEN, SC (United States); Pechersky, M.J.

1997-07-31

62

Leak testing device for pressure vessels  

SciTech Connect

A removable leak test device for radiators and the like is described; consisting of: a base plate adapted to overlap the open top of the neck having diametrically opposite up-turned ears and a central aperture therethrough; toggle latches having handles pivoted on the ears and fingers pivoted on the handles for engaging the under face of the rim; a hollow stem slideable through the central aperture of the base plate, the stem having a threaded section; a resilient seal on the end of the stem for engaging the seat; a compression spring around the stem between the base plate and the seal; a nut threaded on the stem bottomed on the base plate to adjust the compression oof the spring; and means on the stem for attaching a pressure conduit to pressurize the vessel; whereby when the handles are pulled upwardly on the ears, the fingers will pull the base plate toward the rim of the neck to compress the spring and load the seal against the seat.

Jones, J.L.

1989-03-07

63

Controlling and cooling core melts outside the pressure vessel  

Microsoft Academic Search

For future reactors, the control and cooling of ex-vessel corium melts is under consideration to increase the passive safety features even for very unlikely severe accidents. In this context, different research activities are studying ex-vessel corium behaviour and control, including the implementation of a core cooling device outside the reactor pressure vessel in order to prevent basement erosion and to

H Alsmeyer; G Albrecht; G Fieg; U Stegmaier; W Tromm; H Werle

2000-01-01

64

Nonlinear finite element analysis of mechanical characteristics on CFRP composite pressure vessels  

Microsoft Academic Search

CFRP(Carbon Fibre Reinforced Plastic) composite pressure vessel was calculated using finite element program of ANSYS for their mechanical characteristics in this paper. The elastic-plastic model and elements of Solid95 were selected for aluminium alloys of gas cylinder. Also liner-elastic model and layer elements of Shell99 were adopted for carbon fibre\\/epoxy resin. The stress state of CFRP composite pressure vessel was

Dong-xia Liu; Li Liang; Ming Li

2010-01-01

65

Comparison of pressure vessel integrity analyses and approaches for VVER 1000 and PWR vessels for PTS conditions  

Microsoft Academic Search

Currently, license renewals and plant-life extension are important issues for nuclear industry. Pressure vessel integrity is one of the main concerns related to these issues. Pressure vessel integrity is of prime concern for pressurized reactors, since they operate at higher pressures and neutron fluxes when compared to boiling water reactors. Pressure vessel integrity analyses for two commercial pressurized water reactors

Oya Özdere Gülol; Üner Çolak

2003-01-01

66

Composite Pressure Vessel Variability in Geometry and Filament Winding Model.  

National Technical Information Service (NTIS)

Composite pressure vessels (CPVs) are used in a variety of applications ranging from carbon dioxide canisters for paintball guns to life support and pressurant storage on the International Space Station. With widespread use, it is important to be able to ...

N. J. Greene S. J. Green

2012-01-01

67

EPRI activities to address reactor pressure vessel integrity issues  

Microsoft Academic Search

The demonstration of reactor pressure vessel (RPV) structural integrity is an essential element in ensuring the continued safe and reliable operation of US nuclear power plants. The Electric Power Research Institute (EPRI), through its domestic and international member utilities, continues to pursue an aggressive research program to develop technologies and capabilities that will address issues associated with reactor pressure vessel

Stan T Rosinski; Robert G Carter

1999-01-01

68

Reactor Pressure Vessel Head Packaging & Disposal  

SciTech Connect

Reactor Pressure Vessel (RPV) Head replacements have come to the forefront due to erosion/corrosion and wastage problems resulting from the susceptibility of the RPV Head alloy steel material to water/boric acid corrosion from reactor coolant leakage through the various RPV Head penetrations. A case in point is the recent Davis-Besse RPV Head project, where detailed inspections in early 2002 revealed significant wastage of head material adjacent to one of the Control Rod Drive Mechanism (CRDM) nozzles. In lieu of making ASME weld repairs to the damaged head, Davis-Besse made the decision to replace the RPV Head. The decision was made on the basis that the required weld repair would be too extensive and almost impractical. This paper presents the packaging, transport, and disposal considerations for the damaged Davis-Besse RPV Head. It addresses the requirements necessary to meet Davis Besse needs, as well as the regulatory criteria, for shipping and burial of the head. It focuses on the radiological characterization, shipping/disposal package design, site preparation and packaging, and the transportation and emergency response plans that were developed for the Davis-Besse RPV Head project.

Wheeler, D. M.; Posivak, E.; Freitag, A.; Geddes, B.

2003-02-26

69

The effect of stress relaxation loading cycles on the creep behaviour of 2.25Cr–1Mo pressure vessel steel  

Microsoft Academic Search

This paper investigates the effects of repeated stress relaxation loadings and post stress relaxation creep to assess the stress relaxation–creep interaction and microstructural evolution of 2.25Cr–1Mo steel. Prior to creep testing, the microstructure of the material subjected to stress relaxation exhibited a structure which was non-conservative in predicting the remaining creep life of the material. The results obtained in the

S. R. Humphries; W. Y. Yeung; M. D. Callaghan

2011-01-01

70

Recent progress in understanding reactor pressure vessel steel embrittlement  

NASA Astrophysics Data System (ADS)

This paper reviews the current understanding of the basic mechanisms of irradiation embrittlement in reactor pressure vessel steels. Radiation enhanced diffusiona at operating temperatures around 290°C leads to the formation of various ultrafine scale hardening phases, including copper rich and copper catalysed manganese-nickel rich precipitates. Other nanofeatures that do not require copper, so-called matrix defects, include alloy phosphides and carbonitrides as well as defect cluster-solute complexes. Matrix defects that are thermally unstable (anneal) under irradiation play a very important role in mediating flux and temperature effects. The balance of features depends on the composition of the steel and the irradiation conditions. Copper enriched phases, which are the dominant embrittling feature in alloys containing significant trace quantities of this element, are fairly well understood. In contrast, the detailed identity and etiology of the matrix defects and manganese-nickel rich phases that may form in very low copper steels has not yet been established. Embrittlement of typical (Mn-Mo-Ni) pressure vessel steels, manifested as shifts in Charpy V-notch transition temperature, can generally be related to yield stress increases. Yield stress increases from copper rich precipitates are consistent with predictions using defect-obstacle interaction theory coupled with a new model for superposition of the hardening from both pre- and post-irradiation sources of strength. Details of the strengthening contributions from the other irradiation features are not as well established, but appear to be reasonably consistent with theory. These concepts have led to the development of thermodynamic-kinetic-micromechanical models that are broadly consistent with experiment, and rationalize the highly synergistic effects of important irradiation (e.g., temperature, flux, fluence) and metallurgical (e.g., copper, nickel, manganese, phosphorous and heat treatment) variables on both irradiation hardening and hardening recovery during post-irradiation annealing. Open questions can be addressed with a hierarchy of new theoretical and experimental tools, which range from atomistic modeling to tomographic methods of observing the sequence-of-events leading to fracture. Advanced microstructural evolution, microstructure-property and micromechanical models, validated and calibrated by well designed experiments, will greatly enhance our ability to predict pressure vessel embrittlement and to resolve out-standing technical issues.

Odette, G. R.; Lucas, G. E.

71

In-place thermal annealing of nuclear reactor pressure vessels  

Microsoft Academic Search

Radiation embrittlement of ferritic pressure vessel steels increases the ductile-brittle transition temperature and decreases the upper shelf level of toughness as measured by Charpy impact tests. A thermal anneal cycle well above the normal operating temperature of the vessel can restore most of the original Charpy V-notch energy properties. The Amry SM-1A test reactor vessel was wet annealed in 1967

Server

1985-01-01

72

Decreased elastin in vessel walls puts the pressure on  

PubMed Central

Mice haploinsufficient for elastin develop structural changes in vessel walls similar to those seen in patients with mutations in the elastin gene. A new study demonstrates that due to mechanical changes in the vessel wall, these animals exhibit increased mean arterial pressures. The results evoke the possibility that alterations in elastin may contribute to the development of essential hypertension in patients.

D'Armiento, Jeanine

2003-01-01

73

SMART composite high pressure vessels with integrated optical fiber sensors  

Microsoft Academic Search

In this paper application of integrated Optical Fiber Sensors for strain state monitoring of composite high pressure vessels is presented. The composite tanks find broad application in areas such as: automotive industry, aeronautics, rescue services, etc. In automotive application they are mainly used for gaseous fuels storage (like CNG or compressed Hydrogen). In comparison with standard steel vessels, composite ones

Wojciech Blazejewski; Andrzej Czulak; Pawel Gasior; Jerzy Kaleta; Rafal Mech

2010-01-01

74

Lightweight pressure vessels and unitized regenerative fuel cells  

Microsoft Academic Search

Energy storage systems have been designed using lightweight pressure vessels with unitized regenerative fuel cells (URFCs). The vessels provide a means of storing reactant gases required for URFCs; they use lightweight bladder liners that act as inflatable mandrels for composite overwrap and provide a permeation barrier. URFC systems have been designed for zero emission vehicles (ZEVs); they are cost competitive

F. Mitlitsky; B. Myers; A. H. Weisberg

1996-01-01

75

46 CFR 50.30-15 - Class II pressure vessels.  

Code of Federal Regulations, 2011 CFR

...vessels. (a) Class II pressure...subchapter. (b) The first inspection of Class II welded pressure...second inspection of Class II welded pressure...inspector shall check any new material being used...at the time of the first inspection,...

2011-10-01

76

Crashworthy sealed pressure vessel for plutonium transport  

SciTech Connect

A rugged transportation package for the air shipment of radioisotopic materials was recently developed. This package includes a tough, sealed, stainless steel inner containment vessel of 1460 cc capacity. This vessel, intended for a mass load of up to 2 Kg PuO/sub 2/ in various isotopic forms (not to exceed 25 watts thermal activity), has a positive closure design consisting of a recessed, shouldered lid fastened to the vessel body by twelve stainless-steel bolts; sealing is accomplished by a ductile copper gasket in conjunction with knife-edge sealing beads on both the body and lid. Follow-on applications of this seal in newer, smaller packages for international air shipments of plutonium safeguards samples, and in newer, more optimized packages for greater payload and improved efficiency and utility, are briefly presented.

Andersen, J.A.

1980-01-01

77

30 CFR 56.13001 - General requirements for boilers and pressure vessels.  

Code of Federal Regulations, 2013 CFR

...requirements for boilers and pressure vessels. 56.13001 Section...NONMETAL MINES Compressed Air and Boilers § 56.13001...requirements for boilers and pressure vessels. All boilers and pressure vessels shall be...

2013-07-01

78

30 CFR 57.13001 - General requirements for boilers and pressure vessels.  

Code of Federal Regulations, 2013 CFR

...requirements for boilers and pressure vessels. 57.13001 Section...NONMETAL MINES Compressed Air and Boilers § 57.13001...requirements for boilers and pressure vessels. All boilers and pressure vessels shall be...

2013-07-01

79

29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Portable air receivers and other unfired pressure vessels. 1915.172... Portable, Unfired Pressure Vessels, Drums and...1915.172 Portable air receivers and other unfired pressure vessels. (a)...

2013-07-01

80

29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Portable air receivers and other unfired pressure vessels. 1915.172... Portable, Unfired Pressure Vessels, Drums and...1915.172 Portable air receivers and other unfired pressure vessels. (a)...

2009-07-01

81

29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Portable air receivers and other unfired pressure vessels. 1915.172... Portable, Unfired Pressure Vessels, Drums and...1915.172 Portable air receivers and other unfired pressure vessels. (a)...

2010-07-01

82

Residual Stresses at Girth-Butt Welds in Pipes and Pressure Vessels. Quarterly Progress Report, July 15, 1976--October 15, 1976.  

National Technical Information Service (NTIS)

A progress summary is presented for a combined experimental and analytical study to develop mathematical models for predicting residual stresses in girth-butt welds. The program is divided into three tasks, a critical literature review, laboratory tests, ...

E. F. Rybicki

1976-01-01

83

Advanced Technology for Minimum Weight Pressure Vessel System.  

National Technical Information Service (NTIS)

Bosses were made of fiber/resin composite materials to evaluate their potential in lightweight pressure vessels. An approximate 25% weight savings over the standard aluminum boss was achieved without boss failures during burst tests. Polymer liners and me...

M. A. Hamstad E. S. Jessop R. H. Toland

1977-01-01

84

Nonlinear Analyses for Embedded Cracks Under Pressurized Thermal Shock: Comparisons with FAVOR and Weibull Stress Approaches.  

National Technical Information Service (NTIS)

Thick-walled reactor pressure vessels (RPVs) can potentially experience rapid temperature and pressure changes under pressurized thermal shock (PTS) conditions. This work describes progress towards utilization of a Weibull stress approach for cleavage fra...

B. Wasiluk R. H. Dodds X. Qian

2008-01-01

85

Large deflection analysis of conical head pressure vessels  

Microsoft Academic Search

The present work investigates the nonlinear behaviour at and near the junction of cylindrical and conical shells under internal\\u000a or external pressure. The results are useful for studying conical head pressure vessels and components of missiles, spacecrafts,\\u000a underwater vessels, nuclear reactors, etc.Reissner's basic concept for the large deformation of axisymmetric shells, with proper modification and specialization, are used in\\u000a the

1986-01-01

86

Low-Cost, Lightweight Pressure Vessel Proof Test  

NASA Astrophysics Data System (ADS)

This experiment seeks to determine the burst strength of the low-cost, lightweight pressure vessel fabricated by the Suborbital Center of Excellence (SCE). Moreover, the test explores the effects of relatively large gage pressures on material strain for ‘pumpkin-shaped' pressure vessels. The SCE team used pressure transducers and analog gauges to measure the gage pressure while a video camera assembly recorded several gores in the shell for strain analysis. The team loaded the vessel in small intervals of pressure until the structure failed. Upon test completion, the pressure readings and video recordings were analyzed to determine the burst strength and material strain in the shell. The analysis yielded a burst pressure of 13.5 psi while the strain analysis reported in the shell. While the results of this proof test are encouraging, the structure's factor of safety must be increased for actual balloon flights. Furthermore, the pressure vessel prototype must be subjected to reliability tests to show the design can sustain gage pressures for the length of a balloon flight.

Chanez, Eric

87

LOFT Pressurizer Pressure Relief Piping System Stress Analysis and Fatigue Life Report.  

National Technical Information Service (NTIS)

A stress analysis was performed on the LOFT Pressurizer Pressure Relief System to determine if it met the requirements of the ASME Boiler and Pressure Vessel Code, Section III, 1974 Edition, for Class 1 and Class 2 components. Deadweight, thermal expansio...

J. W. Muffett

1978-01-01

88

Reliability-based load and resistance factor design of composite pressure vessel under external hydrostatic pressure  

Microsoft Academic Search

A reliability-based load and resistance factor design procedure for subsea composite pressure vessel subjected to external hydrostatic pressure is presented. The failure criterion for defining the performance function is considered as buckling. A sensitivity analysis is conducted to research influences of statistical characteristics of variables on the partial safety factors and the thickness of pressure vessel. The results shows the

Baoping Cai; Yonghong Liu; Zengkai Liu; Xiaojie Tian; Renjie Ji; Hang Li

89

Light Water Reactor-Pressure Vessel Surveillance project computer system  

SciTech Connect

A dedicated process control computer has been implemented for regulating the metallurgical Pressure Vessel Wall Benchmark Facility (PSF) at the Oak Ridge Research Reactor. The purpose of the PSF is to provide reliable standards and methods by which to judge the radiation damage to reactor pressure vessel specimens. Benchmark data gathered from the PSF will be used to improve and standardize procedures for assessing the remaining safe operating lifetime of aging reactors. The computer system controls the pressure vessel specimen environment in the presence of gamma heating so that in-vessel conditions are simulated. Instrumented irradiation capsules, in which the specimens are housed, contain temperature sensors and electrical heaters. The computer system regulates the amount of power delivered to the electrical heaters based on the temperature distribution within the capsules. Time-temperature profiles are recorded along with reactor conditions for later correlation with specimen metallurgical changes.

Merriman, S.H.

1980-10-01

90

Integrity of PWR pressure vessels during overcooling accidents  

SciTech Connect

The reactor pressure vessel in a pressurized water reactor is normally subjected to temperatures and pressures that preclude propagation of sharp, crack-like defects that might exist in the wall of the vessel. However, there is a class of postulated accidents, referred to as overcooling accidents, that can subject the pressure vessel to severe thermal shock while the pressure is substantial. As a result of such accidents vessels containing high concentrations of copper and nickel, which enhance radiation embrittlement, may possess a potential for extensive propagation of preexistent inner surface flaws prior to the vessel's normal end of life. For the purpose of evaluating this problem a state-of-the-art fracture mechanics model was developed and has been used for conducting parametric analyses and for calculating several recorded PWR transients. Results of the latter analysis indicate that there may be some vessels that have a potential for failure today if subjected to a Rancho Seco (1978) or TMI-2 (1979) type transient. However, the calculational model may be excessively conservative, and this possibility is under investigation.

Cheverton, R.D.; Iskander, S.K.; Whitman, G.D.

1982-01-01

91

Integrity of PWR pressure vessels during overcooling accidents  

SciTech Connect

The reactor pressure vessel in a pressurized water reactor is normally subjected to temperatures and pressures that preclude propagation of sharp, crack-like defects that might exist in the wall of the vessel. However, there is a class of postulated accidents, referred to as overcooling accidents, that can subject the pressure vessel to severe thermal shock while the pressure is substantial. As a result of such accidents, vessels containing high concentrations of copper and nickel, which enhance radiation embrittlement, may possess a potential for extensive propagation of preexistent inner surface flaws prior to the vessel's normal end of life. A state-of-the-art fracture-mechanics model was developed and has been used for conducting parametric analyses and for calculating several recorded PWR transients. Results of the latter analysis indicate that there may be some vessels that have a potential for failure in a few years if subjected to a Rancho Seco-type transient. However, the calculational model may be excessively conservative, and this possibility is under investigation.

Cheverton, R.D.; Iskander, S.K.; Whitman, G.D.

1982-01-01

92

Hydroide Storage Vessel wall stress measurements.  

National Technical Information Service (NTIS)

Holographic Interferometry and strain gauge measurements were used to determine whether a prototype Hydride Storage Vessel (HSV) swelled while it was loaded in eleven stages with hydrogen. Bed swelling is inferred from deformation of the surface of the HS...

E. A. Clark M. J. Pechersky

1997-01-01

93

Elastic analysis of heterogeneous thick-walled spherical pressure vessels with parabolic varying properties  

NASA Astrophysics Data System (ADS)

On the basis of plane elasticity theory (PET), the displacement and stress components in a thick-walled spherical pressure vessels made of heterogeneous materials subjected to internal and external pressure is developed. The mechanical properties except the Poisson's ratio are assumed to obey the parabolic variations throughout the thickness. Effect of material inhomogeneity on the elastic deformations and stresses is investigated. The analytical solutions and the solutions carried out through the FEM have a good agreement. The values used in this study are arbitrary chosen to demonstrate the effect of inhomogeneity on displacements, and stresses distributions.

Karami, Keyhan; Abedi, Majid; Zamani Nejad, Mohammad; Lotfian, Mohammad Hassan

2012-12-01

94

Dual shell pressure balanced reactor vessel. Final project report  

Microsoft Academic Search

The Department of Energy`s Office of Energy Research (OER) has previously provided support for the development of several chemical processes, including supercritical water oxidation, liquefaction, and aqueous hazardous waste destruction, where chemical and phase transformations are conducted at high pressure and temperature. These and many other commercial processes require a pressure vessel capable of operating in a corrosive environment where

R. J. Robertus; A. G. Fassbender

1994-01-01

95

On the thermal hydraulics of Magnox reactor pressure vessel insulation  

Microsoft Academic Search

The thermal conductivity of multiple plate insulation used in ‘Magnox’ reactor pressure vessels has been investigated experimentally. In the reactor application the fluid within the insulation pack is carbon dioxide at 20bar, however, in this experimental investigation the insulation was tested in air at lower pressures. The conductivity of the insulation was measured using a test facility based on the

B. P. Axcell; T. K. Lim; M. A. Cotton

2007-01-01

96

Transient Response of FGM Pressure Vessels  

NASA Astrophysics Data System (ADS)

The present study aims to investigate the transient behavior of thick-walled cylinders under dynamic internal pressure. Analytical solutions are possible only for simple time-dependent pressure functions. The solution procedure presented is general in the sense that the pressure applied may be an arbitrary continuous function of time, impulsive or given in a discrete form. The material considered is isotropic and heterogeneous with properties varying in the radial direction termed as Functionally Graded Material (FGM). Laplace transform method is used and the inversion into the time domain is performed using the modified Durbin's method. Verification of the numerical procedure is performed by comparing the results with those of an analytical solution available in the literature for a simple exponentially-varying pressure. The inhomogeneity constant in the material property model is shown to have a significant effect on the transient response.

Pekel, Hakan; Keles, Ibrahim; Temel, Beytullah; Tutuncu, Naki

97

Proceedings of the 13. international conference on NDE in the nuclear and pressure vessel industries  

SciTech Connect

This book is divided into the following sections: plenary session; role of NDE (nondestructive evaluation) 1; x-ray technology; role of NDE 2; piping and major components; reactor pressure vessel inspection; advanced ultrasonic inspection technologies 1; performance demonstration initiative and inspection qualification approaches; electromagnetic technologies; advanced ultrasonic inspection technologies 2; advanced inspection technologies 1; advanced inspection technologies 2; material characterization 1; material characterization 2; steam generators 1; steam generators 2; BWR reactor pressure vessel inspection; modelling of NDE inspections; turbine inspection; stress measurement; and control rod drive mechanism. Separate abstracts were prepared for 66 papers in this book.

Iida, Kunihiro [ed.] [Shibaura Inst. of Technology, Tokyo (Japan); Light, G.M [ed.] [Southwest Research Inst., San Antonio, TX (United States); Whittle, M.J. [ed.] [John Whittle and Associates, Cheshire (United Kingdom)

1995-08-01

98

Hydroide Storage Vessel wall stress measurements  

Microsoft Academic Search

Holographic Interferometry and strain gauge measurements were used to determine whether a prototype Hydride Storage Vessel (HSV) swelled while it was loaded in eleven stages with hydrogen. Bed swelling is inferred from deformation of the surface of the HSV. No swelling was detected, even after saturating the hydride material inside the HSV. The large chunky morphology of the titanium is

E. A. Clark; M. J. Pechersky

1997-01-01

99

Using the adaptive SMA composite cylinder concept to reduce radial dilation in composite pressure vessels  

NASA Astrophysics Data System (ADS)

Composite materials are widely used in the design of pressurized gas and fluid vessels for applications ranging from underground gasoline storage tanks to rocket motors for the space shuttle. In the design of a high pressure composite vessel (Pi > 12 Ksi), thick-wall (R/h < 15) vessels are required. For efficient material use in composite material vessels, the radial dilation (expansion or swelling) of the composite vessel can often approach values nearing 2 percent of the diameter. Over long periods of internal pressure loading over elevated temperatures, composite material cylinders may also experience substantial creep. The short term dilation and long term creep are not problematic for applications requiring only the containment of the pressurized fluid. In applications where metallic liners are required, however, substantial dilation and creep causes plastic yielding which leads to reduced fatigue life. To applications such as a hydraulic accumulator, where a piston is employed to fit and seal the fluid in the composite cylinder, the dilation and creep may allow leakage and pressure loss around the piston. A concept called the adaptive composite cylinder is experimentally presented. Shape memory alloy wire in epoxy resin is wrapped around or within polymer matrix composite cylinders to reduce radial dilation of the cylinder. Experimental results are presented that demonstrate the ability of the SMA wire layers to reduce radial dilation. Results from experimental testing of the recovery stress fatigue response of nitinol shape memory alloy wires is also presented.

Paine, Jeffrey S.; Rogers, Craig A.

1995-05-01

100

SMART composite high pressure vessels with integrated optical fiber sensors  

NASA Astrophysics Data System (ADS)

In this paper application of integrated Optical Fiber Sensors for strain state monitoring of composite high pressure vessels is presented. The composite tanks find broad application in areas such as: automotive industry, aeronautics, rescue services, etc. In automotive application they are mainly used for gaseous fuels storage (like CNG or compressed Hydrogen). In comparison with standard steel vessels, composite ones have many advantages (i.e. high mechanical strength, significant weight reduction, etc). In the present work a novel technique of vessel manufacturing, according to this construction, was applied. It is called braiding technique, and can be used as an alternative to the winding method. During braiding process, between GFRC layers, two types of optical fiber sensors were installed: point sensors in the form of FBGs as well as interferometric sensors with long measuring arms (SOFO®). Integrated optical fiber sensors create the nervous system of the pressure vessel and are used for its structural health monitoring. OFS register deformation areas and detect construction damages in their early stage (ensure a high safety level for users). Applied sensor system also ensured a possibility of strain state monitoring even during the vessel manufacturing process. However the main application of OFS based monitoring system is to detect defects in the composite structure. An idea of such a SMART vessel with integrated sensor system as well as an algorithm of defect detection was presented.

Blazejewski, Wojciech; Czulak, Andrzej; Gasior, Pawel; Kaleta, Jerzy; Mech, Rafal

2010-03-01

101

Temperature and pressure influence on explosion pressures of closed vessel propane–air deflagrations  

Microsoft Academic Search

An experimental study on pressure evolution during closed vessel explosions of propane–air mixtures was performed, for systems with various initial concentrations and pressures ([C3H8]=2.50–6.20vol.%, p0=0.3–1.2bar). The explosion pressures and explosion times were measured in a spherical vessel (?=10cm), at various initial temperatures (T0=298–423K) and in a cylindrical vessel (?=10cm; h=15cm), at ambient initial temperature. The experimental values of explosion pressures

Domnina Razus; Venera Brinzea; Maria Mitu; Dumitru Oancea

2010-01-01

102

Neural network/acoustic emission burst pressure prediction for impact damaged composite pressure vessels  

SciTech Connect

Acoustic emission signal analysis has been used to measure the effect impact damage has on the burst pressure of 146 mm (5.75 in.) diameter graphite/epoxy and the organic polymer, Kevlar/epoxy filament wound pressure vessels. Burst pressure prediction models were developed by correlating the differential acoustic emission amplitude distribution collected during low level hydroproof tests to known burst pressures using backpropagation artificial neural networks. Impact damage conditions ranging from barely visible to obvious fiber breakage, matrix cracking, and delamination were included in this work. A simulated (inert) propellant was also cast into a series of the vessels from each material class, before impact loading, to provide boundary conditions during impact that would simulate those found on solid rocket motors. The results of this research effort demonstrate that a quantitative assessment of the effects that impact damage has on burst pressure can be made for both organic polymer/epoxy and graphite/epoxy pressure vessels. Here, an artificial neural network analysis of the acoustic emission parametric data recorded during low pressure hydroproof testing is used to relate burst pressure to the vessel`s acoustic signature. Burst pressure predictions within 6.0% of the actual failure pressure are demonstrated for a series of vessels.

Walker, J.L.; Workman, G.L. [Univ. of Alabama, Huntsville, AL (United States); Russell, S.S. [National Aeronautics and Space Administration, Huntsville, AL (United States). Marshall Space Flight Center; Hill, E.V.K. [Embry-Riddle Aeronautical Univ., Daytona Beach, FL (United States)

1997-08-01

103

Thermoelastic\\/plastic semi-analytical solution of incompressible functionally graded spherical pressure vessel under thermo-mechanical loading  

Microsoft Academic Search

In this paper, numerical solutions to assess partially plastic and fully plastic deformation behavior of a functionally graded\\u000a spherical pressure vessel are presented. The modulus of elasticity of the material is assumed to vary nonlinearly in the radial\\u000a direction and axisymmetric displacements and stresses in the functionally graded spherical vessel subjected to thermal loading\\u000a and uniform internal pressure are determined

S. Rash Ahmadi; M. Sheikhlou; V. Mahmood Gharebagh

104

Cleavage Fracture Modeling of Pressure Vessels Under Transient Thermo-Mechanical Loading  

SciTech Connect

Abstract The next generation of fracture assessment procedures for nuclear reactor pressure vessels (RPVs) will combine nonlinear analyses of crack-front response with stochastic treatments of crack size, shape, orientation, location, material properties and thermal-pressure transients. The projected computational demands needed to support stochastic approaches with detailed 3-D, nonlinear stress analyses of vessels containing defects appear well beyond current and near-term capabilities. In the interim, 2-D models be-come appealing to approximate certain classes of critical flaws in RPVs, and have computational demands within reach for stochastic frameworks. The present work focuses on the capability of 2-D models to provide values for the Weibull stress fracture parameter with accuracy comparable to those from very detailed 3-D models. Weibull stress approaches provide one route to connect nonlinear vessel response with fracture toughness values measured using small laboratory specimens. The embedded axial flaw located in the RPV wall near the cladding-vessel interface emerges from current linear-elastic, stochastic investigations as a critical contributor to the conditional probability of initiation. Three different types of 2-D models reflecting this configuration are subjected to a thermal-pressure transient characteristic of a critical pressurized thermal shock event. The plane-strain, 2-D models include: the modified boundary layer (MBL) model, the middle tension (M(T)) model, and the 2-D RPV model. The 2-D MBL model provides a high quality estimate for the Weibull stress but only in crack-front regions with a positive T-stress. For crack-front locations with low constraint (T-stress < 0), the M(T) specimen provides very accurate Weibull stress values but only for pressure load acting alone on the RPV. For RPVs under a combined thermal-pressure transient, Weibull stresses computed from the 2-D RPV model demonstrate close agreement with those computed from the corresponding crack-front locations in the 3-D RPV model having large negative T-stresses. Applications of this family of 2-D models provide Weibull stress values in excellent agreement with very detailed 3-D models while retaining practical levels of computational effort.

Qian, Xudong [National University of Singapore; Dodds, Robert [University of Illinois; Yin, Shengjun [ORNL; Bass, Bennett Richard [ORNL

2008-01-01

105

Cleavage Fracture Modeling of Pressure Vessels under Transient Thermo-Mechanical Loading  

SciTech Connect

The next generation of fracture assessment procedures for nuclear reactor pressure vessels (RPVs) will combine nonlinear analyses of crack-front response with stochastic treatments of crack size, shape, orientation, location, material properties and thermal-pressure transients. The projected computational demands needed to support stochastic approaches with detailed 3-D, nonlinear stress analyses of vessels containing defects appear well beyond current and near-term capabilities. In the interim, 2-D models become appealing to approximate certain classes of critical flaws in RPVs, and have computational demands within reach for stochastic frameworks. The present work focuses on the capability of 2-D models to provide values for the Weibull stress fracture parameter with accuracy comparable to those from very detailed 3-D models. Weibull stress approaches provide one route to connect nonlinear vessel response with fracture toughness values measured using small laboratory specimens. The embedded axial flaw located in the RPV wall near the cladding-vessel interface emerges from current linear-elastic, stochastic investigations as a critical contributor to the conditional probability of initiation. Three different types of 2-D models reflecting this configuration are subjected to a thermal-pressure transient characteristic of a critical pressurized thermal shock event. The plane-strain, 2-D models include: the modified boundary layer (MBL) model, the middle tension (M(T)) model, and the 2-D RPV model. The 2-D MBL model provides a high quality estimate for the Weibull stress but only in crack-front regions with a positive T-stress. For crack-front locations with low constraint (T-stress < 0), the M(T) specimen provides very accurate Weibull stress values but only for pressure load acting alone on the RPV. For RPVs under a combined thermal-pressure transient, Weibull stresses computed from the 2-D RPV model demonstrate close agreement with those computed from the corresponding crack-front locations in the 3-D RPV model having large negative T-stresses. Applications of this family of 2-D models provide Weibull stress values in excellent agreement with very detailed 3-D models while retaining practical levels of computational effort.

Qian, Xudong [National University of Singapore; Dodds, Robert [University of Illinois; Yin, Shengjun [ORNL; Bass, Bennett Richard [ORNL

2008-02-01

106

Reactor Pressure Vessel Preparation for Shipment and Burial.  

National Technical Information Service (NTIS)

This paper describes the preparation of the Shippingport Reactor Pressure Vessel/Neutron Shield Tank (RPV/NST) for removal, barge shipment and burial. The preparation of the RPV/NST package results in a monolithic package that more than meets the requirem...

K. I. Kea

1987-01-01

107

Radiation Hardening in Magnox Pressure-Vessel Steels  

Microsoft Academic Search

The ferritic steels used for reactor pressure vessels undergo a marked transition from ductile to brittle fracture behaviour over a relatively narrow temperature range. For most unirradiated mild steels the ductile to brittle transition temperature (d.b.t.t.) is between -50 degrees and 20 degrees C. The process of irradiation hardening, through the formation of clusters of intersitial or vacancy defects, increases

S. B. Fisher; J. E. Harbottle; N. Aldridge

1985-01-01

108

Fatigue crack initiation and propagation behavior of pressure vessel steels  

Microsoft Academic Search

In this investigation, replication techniques were employed to monitor the fatigue crack initiation and growth behavior of a pressure vessel steel. Crack initiation was found to be related to the presence of inclusions. In the crack initiation region, transgranular fracture was the prime mode of fracture mixed with some intergranular fracture. As the crack propagated, the extent of intergranular fracture

P. K. Liaw; C. Y. Yang; S. S. Palusamy; W. Ren

1997-01-01

109

On the thermal hydraulics of Magnox reactor pressure vessel insulation  

Microsoft Academic Search

The paper presents a computational study of laminar flow and heat transfer in a layer of the multiple plate insulation used to line the interior surface of ‘Magnox’ reactor pressure vessels. The flow passage consists of a 2mm deep channel, which is plane on its upper surface and has raised ‘dimples’ on its lower surface. Under forced convection conditions strong

M. A. Cotton; T. K. Lim; B. P. Axcell

2007-01-01

110

MATERIAL REQUIREMENTS FOR LONG-LIFE PRESSURE VESSELS  

Microsoft Academic Search

A treatment is given of the various possible modes of failure of a ; pressure vessel intended for long service and of the material properties which ; are of significance in preventing them. The failure modes discussed are: plastic ; deformation and bursting; brittle fracture; fatigue failure; creep deformation ; and creep rupture; and corrosion. The need for additional information

B. F. Langer; W. L. Harding

1963-01-01

111

ECN Pressure and Vacuum Vessel Engineering Notes  

SciTech Connect

The following calculations arranged in a spreadsheet format derive the flowrate from both ECN relieving devices. In this case it is assumed that the ECN is full of liquid argon and it is in its steady state cooling mode. One of the other cryostats is assumed to be cooling down while the other is being filled with LAr. Other assumptions in this analysis include: (1) Pressure in the cryostat is 19.75 psig (1.16X(MAWP+FV)). (2) Gaseous Nitrogen is concurrently flowing in the vent piping at a rate of 3477 lb/hr. This is derived from 0.3 gpm required for ECN steady state conditions, 4 gpm required for cooldown (max.), and 5 gpm required for filling with LAr (max.). (3) Mixture mass flows are at their maximum at the junction of the relief device outlets on the ECN (GN2 mass flow actually increases gradually at junctions toward the ECS and there is a short segment of piping between the GAr outlets and the condenser exhaust). (4) The temperature in the vent piping is negligible since a large majority of this piping is insulated. (5) All flows are treated as incompressible (max. Mach No. < 0.3). (6) The temperature of the GN2 prior to mixing in the vent manifold is 84 K, saturated property at 2 atm. (7) Flow equations apply to weight-averaged mixture densities and viscosities.

Wu, J.; Dixon, K.; /Fermilab

1991-10-17

112

Residual life assessment of light water reactor pressure vessels  

SciTech Connect

The service-dependent degradation (agina) of light water reactor (LWR) pressure vessels due to irradiation embrittlement is discussed in this paper. The major variable which influence the irradiation embrittlement of LWR vessels are the copper and nickel content of the vessel materials and the fluence. The vessel beltline region is subjected to the largest fluences. A surveillance program, which consists of tensile and Charpy-V-notch (CVN) testing of irradiated specimens of base, heat-affected-zone, and weld materials, is required to monitor changes in their embrittlement. Three main unresolved technical issues are: the limited range and accuracy of the current correlations for caluclating shifts in the reference temperature for nil-ductility transition (RT/sub NDT/) and changes in the Charpy upper shelf energy: the need to demonstrate the conservatism of using CVN-based RT/sub NDT/ shifts for certain sensitive reactor pressure vessel materials; and the type of surveillance program required for any renewed operating license period. The damage caused by irradiation embrittlement can impact plant operating procedures, including heatupcooldown and hydrostatic test procedures, as well as the acceptability of various plant transients. 23 refs., 3 figs., 1 tab

Shah, V.N.; Server, W.L.; Odette, G.R.; Swaroop, A.V.

1987-01-01

113

Taxane-induced Apoptosis Decompresses Blood Vessels and Lowers Interstitial Fluid Pressure in Solid Tumors: Clinical Implications1  

Microsoft Academic Search

Elevated tumor interstitial fluid pressure (IFP) is partly responsible for the poor penetration and distribution of therapeutic agents in solid tu- mors. The etiology of tumor interstitial hypertension is poorly understood. We have postulated that the solid stress generated by tumor cells growing in a confined space compresses blood vessels and increases tumor micro- vascular pressure and IFP. To test

Genevieve Griffon-Etienne; Yves Boucher; Christian Brekken; Herman D. Suit; Rakesh K. Jain

1999-01-01

114

Reactor pressure vessel failure probability following through-wall cracks due to pressurized thermal shock events  

Microsoft Academic Search

A fracture mechanics model was developed at the Pacific Northwest Laboratory (PNL) to predict the behavior of a reactor pressure vessel following a through-wall crack that occurs during a pressurized thermal shock (PTS) event. This study, which contributed to a US Nuclear Regulatory Commission (NRC) program to study PTS risk, was coordinated with the Integrated Pressurized Thermal Shock (IPTS) Program

F. A. Simonen; M. R. Garnich; E. P. Simonen; S. H. Bian; K. K. Nomura; W. E. Anderson; L. T. Pedersen

1986-01-01

115

Behavior of a corium jet in high pressure melt ejection from a reactor pressure vessel.  

National Technical Information Service (NTIS)

This report provides results from analytical and experimental investigations on the behavior of a gas supersaturated molten jet expelled from a pressurized vessel. Aero-hydrodynamic stability of liquid jets in gas, stream degassing of molten metals and ga...

W. Frid

1987-01-01

116

Pressurized thermal shock probabilistic fracture mechanics sensitivity analysis for Yankee Rowe reactor pressure vessel  

Microsoft Academic Search

The Nuclear Regulatory Commission (NRC) requested Oak Ridge National Laboratory (ORNL) to perform a pressurized-thermal-shock (PTS) probabilistic fracture mechanics (PFM) sensitivity analysis for the Yankee Rowe reactor pressure vessel, for the fluences corresponding to the end of operating cycle 22, using a specific small-break-loss- of-coolant transient as the loading condition. Regions of the vessel with distinguishing features were to be

T. L. Dickson; R. D. Cheverton; J. W. Bryson; B. R. Bass; D. K. M. Shum; J. A. Keeney

1993-01-01

117

Using the adaptive SMA composite cylinder concept to reduce radial dilation in composite pressure vessels  

Microsoft Academic Search

Composite materials are widely used in the design of pressurized gas and fluid vessels for applications ranging from underground gasoline storage tanks to rocket motors for the space shuttle. In the design of a high pressure composite vessel (Pi > 12 Ksi), thick-wall (R\\/h < 15) vessels are required. For efficient material use in composite material vessels, the radial dilation

Jeffrey S. Paine; Craig A. Rogers

1995-01-01

118

Insulated pressure vessels for hydrogen storage on vehicles  

Microsoft Academic Search

Probably the most significant hurdle for hydrogen vehicles is storing sufficient hydrogen onboard. Three viable technologies for storing hydrogen fuel on cars are: compressed gas, metal hydride adsorption, and cryogenic liquid. However, each of these has significant disadvantages: volume, weight, boiling losses, or energy to compress or liquefy the hydrogen.Insulated pressure vessels can reduce these problems for hydrogen-fueled light-duty vehicles.

S. M. Aceves; G. D. Berry; G. D. Rambach

1998-01-01

119

H.B. Robinson-2 pressure vessel benchmark  

SciTech Connect

The H. B. Robinson Unit 2 Pressure Vessel Benchmark (HBR-2 benchmark) is described and analyzed in this report. Analysis of the HBR-2 benchmark can be used as partial fulfillment of the requirements for the qualification of the methodology for calculating neutron fluence in pressure vessels, as required by the U.S. Nuclear Regulatory Commission Regulatory Guide DG-1053, Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence. Section 1 of this report describes the HBR-2 benchmark and provides all the dimensions, material compositions, and neutron source data necessary for the analysis. The measured quantities, to be compared with the calculated values, are the specific activities at the end of fuel cycle 9. The characteristic feature of the HBR-2 benchmark is that it provides measurements on both sides of the pressure vessel: in the surveillance capsule attached to the thermal shield and in the reactor cavity. In section 2, the analysis of the HBR-2 benchmark is described. Calculations with the computer code DORT, based on the discrete-ordinates method, were performed with three multigroup libraries based on ENDF/B-VI: BUGLE-93, SAILOR-95 and BUGLE-96. The average ratio of the calculated-to-measured specific activities (C/M) for the six dosimeters in the surveillance capsule was 0.90 {+-} 0.04 for all three libraries. The average C/Ms for the cavity dosimeters (without neptunium dosimeter) were 0.89 {+-} 0.10, 0.91 {+-} 0.10, and 0.90 {+-} 0.09 for the BUGLE-93, SAILOR-95 and BUGLE-96 libraries, respectively. It is expected that the agreement of the calculations with the measurements, similar to the agreement obtained in this research, should typically be observed when the discrete-ordinates method and ENDF/B-VI libraries are used for the HBR-2 benchmark analysis.

Remec, I.; Kam, F.B.K.

1998-02-01

120

Temperature and pressure influence on explosion pressures of closed vessel propane-air deflagrations.  

PubMed

An experimental study on pressure evolution during closed vessel explosions of propane-air mixtures was performed, for systems with various initial concentrations and pressures ([C(3)H(8)]=2.50-6.20 vol.%, p(0)=0.3-1.2 bar). The explosion pressures and explosion times were measured in a spherical vessel (Phi=10 cm), at various initial temperatures (T(0)=298-423 K) and in a cylindrical vessel (Phi=10 cm; h=15 cm), at ambient initial temperature. The experimental values of explosion pressures are examined against literature values and compared to adiabatic explosion pressures, computed by assuming chemical equilibrium within the flame front. The influence of initial pressure, initial temperature and fuel concentration on explosion pressures and explosion times are discussed. At constant temperature and fuel/oxygen ratio, the explosion pressures are linear functions of total initial pressure, as reported for other fuel-air mixtures. At constant initial pressure and composition, both the measured and calculated (adiabatic) explosion pressures are linear functions of reciprocal value of initial temperature. Such correlations are extremely useful for predicting the explosion pressures of flammable mixtures at elevated temperatures and/or pressures, when direct measurements are not available. PMID:19818553

Razus, Domnina; Brinzea, Venera; Mitu, Maria; Oancea, Dumitru

2009-09-23

121

Application of Negligible Creep Criteria to Candidate Materials for HTGR Pressure Vessels  

SciTech Connect

Two of the proposed High Temperature Gas Reactors (HTGRs) under consideration for a demonstration plant have the design object of avoiding creep effects in the reactor pressure vessel (RPV) during normal operation. This work addresses the criteria for negligible creep in Subsection NH, Division 1 of the ASME B&PV (Boiler and Pressure Vessel) Code, Section III, other international design codes and some currently suggested criteria modifications and their impact on permissible operating temperatures for various reactor pressure vessel materials. The goal of negligible creep could have different interpretations depending upon what failure modes are considered and associated criteria for avoiding the effects of creep. It is shown that for the materials of this study, consideration of localized damage due to cycling of peak stresses results in a lower temperature for negligible creep than consideration of the temperature at which the allowable stress is governed by creep properties. In assessing the effect of localized cyclic stresses it is also shown that consideration of cyclic softening is an important effect that results in a higher estimated temperature for the onset of significant creep effects than would be the case if the material were cyclically hardening. There are other considerations for the selection of vessel material besides avoiding creep effects. Of interest for this review are (1) the material s allowable stress level and impact on wall thickness (the goal being to minimize required wall thickness) and (2) ASME Code approval (inclusion as a permitted material in the relevant Section and Subsection of interest) to expedite regulatory review and approval. The application of negligible creep criteria to two of the candidate materials, SA533 and Mod 9Cr-1Mo (also referred to as Grade 91), and to a potential alternate, normalized and tempered 2 Cr-1Mo, is illustrated and the relative advantages and disadvantages of the materials are discussed.

Jetter, Robert I [Consultant; Sham, Sam [ORNL; Swindeman, Robert W [Consultant

2011-01-01

122

Experimental Investigation of Composite Pressure Vessel Performance and Joint Stiffness for Pyramid and Inverted Pyramid Joints.  

National Technical Information Service (NTIS)

The focus of this study is on the suitability in the application of classical laminate theory analysis tools for filament wound pressure vessels with adhesive laminated joints in particular: pressure vessel wall performance, joint stiffness and failure pr...

J. M. Verhage M. V. Bower

2001-01-01

123

46 CFR 167.25-5 - Inspection of boilers, pressure vessels, piping and appurtenances.  

Code of Federal Regulations, 2010 CFR

...false Inspection of boilers, pressure vessels, piping and appurtenances...SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Marine Engineering...25-5 Inspection of boilers, pressure vessels, piping and...

2009-10-01

124

46 CFR 167.25-1 - Boilers, pressure vessels, piping and appurtenances.  

Code of Federal Regulations, 2010 CFR

...CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Marine Engineering...25-1 Boilers, pressure vessels, piping and...reconverted to use as nautical school ships on or after...standards for boilers, pressure vessels, piping...

2009-10-01

125

46 CFR 167.25-5 - Inspection of boilers, pressure vessels, piping and appurtenances.  

Code of Federal Regulations, 2010 CFR

...false Inspection of boilers, pressure vessels, piping and appurtenances...SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Marine Engineering...25-5 Inspection of boilers, pressure vessels, piping and...

2010-10-01

126

46 CFR 167.25-1 - Boilers, pressure vessels, piping and appurtenances.  

Code of Federal Regulations, 2010 CFR

...CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Marine Engineering...25-1 Boilers, pressure vessels, piping and...reconverted to use as nautical school ships on or after...standards for boilers, pressure vessels, piping...

2010-10-01

127

30 CFR 57.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2013 CFR

... Inspection of compressed-air receivers and other unfired pressure vessels. 57.13015 Section... Inspection of compressed-air receivers and other unfired pressure vessels. (a) Compressed-air receivers and other...

2013-07-01

128

30 CFR 56.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.  

Code of Federal Regulations, 2013 CFR

... Inspection of compressed-air receivers and other unfired pressure vessels. 56.13015 Section... Inspection of compressed-air receivers and other unfired pressure vessels. (a) Compressed-air receivers and other...

2013-07-01

129

Hydrogen attack of pressure-vessel steel. Progress report, April 1, 1980-March 31, 1981  

SciTech Connect

The nucleation and growth of methane bubbles in the hydrogen attack of pressure vessel steel has been shown to obey models developed to describe the growth of bubbles limiting the creep ductility of metals. This has been done through studies of the effect of prior deformation on bubble nucleation as well as the effect of methane pressure (stress) and temperature on growth kinetics. A comprehensive model of the factors limiting growth has been developed. Its application to the hydrogen attack of a 2 1/4 Cr-1 Mo steel leads to several interesting predictions.

Shewmon, P.G.

1980-12-01

130

Slideline verification for multilayer pressure vessels and piping analysis including strain hardening  

SciTech Connect

Nonlinear finite element computer codes with slideline algorithm implementations are useful for the analysis of prestressed pressure vessels and piping. This paper presents closed form solutions including the effects of linear strain hardening useful for verifying slideline implementations for this application. The solutions describe stresses and displacements of an internally pressurized inner sphere initially separated from an outer sphere by a uniform gap. Linear strain hardening material behavior following yield for the inner sphere and elastic material behavior for the outer sphere are assumed. Comparison of closed form and finite element results evaluates the usefulness of the closed form solutions and the validity of the slideline implementation used. 9 refs., 9 figs.

Van Gulick, L.A.

1985-01-01

131

Investigation of postweld heat treatment of quenched and tempered pressure vessel steels  

Microsoft Academic Search

Longitudinal and circumferential welds in transportable pressure vessels are produced by submerged-arc welding using a single vee preparation and multiple weld runs. Quenched and tempered (QT) steels, which are commonly used for transportable pressure vessels, require mandatory postweld heat treatment (PWHT) regardless of the plate thickness. During their life transportable pressure vessels may have up to four PWHT cycles, and

Zoran Sterjovski

2003-01-01

132

A new method of nondestructive measurement for assessment of material degradation of aged reactor pressure vessels  

Microsoft Academic Search

A method, MIM (magnetic interrogation method), is proposed for nondestructive measurement of radiation damage of nuclear reactor pressure vessels. The method relies on good correlation between the levels of radiation-induced hardness change and magnetic coercivity change in pressure vessel steel. A part of the pressure vessel to be inspected is magnetized with two-pole magnetic yokes through the overlay clad of

K. Ara; N. Ebine; N. Nakajima

1996-01-01

133

Low Pressure Corium Dispersion Experiments with Lateral Failure in the Bottom Head of the Pressure Vessel  

Microsoft Academic Search

Experiments were performed in a scaled annular cavity design, to investigate melt dispersal from the reactor pit when the reactor pressure vessel lower head fails at low system pressure of less than 2 MPa. In the part of the experimental program presented in this paper, the fluid dynamics of the dispersion process was studied using model fluids, water or bismuth

L. MEYER; M. GARGALLO

134

PRESSURIZATION OF CONTAINMENT VESSELS FROM PLUTONIUM OXIDE CONTENTS  

SciTech Connect

Transportation and storage of plutonium oxide is typically done using a convenience container to hold the oxide powder which is then placed inside a containment vessel. Intermediate containers which act as uncredited confinement barriers may also be used. The containment vessel is subject to an internal pressure due to several sources including; (1) plutonium oxide provides a heat source which raises the temperature of the gas space, (2) helium generation due to alpha decay of the plutonium, (3) hydrogen generation due to radiolysis of the water which has been adsorbed onto the plutonium oxide, and (4) degradation of plastic bags which may be used to bag out the convenience can from a glove box. The contributions of these sources are evaluated in a reasonably conservative manner.

Hensel, S.

2012-03-27

135

Jam proof closure assembly for lidded pressure vessels  

DOEpatents

An expendable closure assembly is provided for use (in multiple units) with a lockable pressure vessel cover along its rim, such as of an autoclave. This assembly is suited to variable compressive contact and locking with the vessel lid sealing gasket. The closure assembly consists of a thick walled sleeve insert for retention in the under bores fabricated in the cover periphery and the sleeve is provided with internal threading only. A snap serves as a retainer on the underside of the sleeve, locking it into an under bore retention channel. Finally, a standard elongate externally threaded bolt is sized for mating cooperation with the so positioned sleeve, whereby the location of the bolt shaft in the cover bore hole determines its compressive contact on the underlying gasket.

Cioletti, Olisse C. (Pittsburgh, PA)

1992-01-01

136

Jam proof closure assembly for lidded pressure vessels  

DOEpatents

An expendable closure assembly is provided for use (in multiple units) with a lockable pressure vessel cover along its rim, such as of an autoclave. This assembly is suited to variable compressive contact and locking with the vessel lid sealing gasket. The closure assembly consists of a thick walled sleeve insert for retention in the under bores fabricated in the cover periphery and the sleeve is provided with internal threading only. A snap serves as a retainer on the underside of the sleeve, locking it into an under bore retention channel. Finally, a standard elongate externally threaded bolt is sized for mating cooperation with the so positioned sleeve, whereby the location of the bolt shaft in the cover bore hole determines its compressive contact an the underlying gasket.

Cioletti, O.C.

1991-01-01

137

Jam proof closure assembly for lidded pressure vessels  

DOEpatents

An expendable closure assembly is provided for use (in multiple units) with a lockable pressure vessel cover along its rim, such as of an autoclave. This assembly is suited to variable compressive contact and locking with the vessel lid sealing gasket. The closure assembly consists of a thick walled sleeve insert for retention in the under bores fabricated in the cover periphery and the sleeve is provided with internal threading only. A snap serves as a retainer on the underside of the sleeve, locking it into an under bore retention channel. Finally, a standard elongate externally threaded bolt is sized for mating cooperation with the so positioned sleeve, whereby the location of the bolt shaft in the cover bore hole determines its compressive contact an the underlying gasket.

Cioletti, O.C.

1991-12-31

138

[Model experiment and numerical simulation of marginal pressure in the flow field downstream of the stenostic vessel in vitro].  

PubMed

For the defects of interpreting the relationship between the distribution and severity of vascular stenostic disease and the low shear stress, the study focus on and explore the rules of the pressure distribution and variation downstream of the stenostic vessel with the numerical simulation and the hydrodynamic model of turbulent flow separation area for in vitro experiment. The results reveal that there is a good compatibility between the model experiment and the numerical simulation; there exists a marked pressure decrease downstream of the stenosis. And the distribution area of low pressure is similar to the characteristic distribution of the stenostic vessel diseases. The study suggested that the numerical simulation can be applied in the study of micro-flow field; the presure distribution and variatioin downstream of the stenostic vessel maybe another factor to trigger the pathogenesis of vessel stenostic diseases. PMID:16706352

Guo, Yingqiang; Shi, Yingkan; Zhang, Jianmin; Xue, Weilin; Liu, Shanjun

2006-04-01

139

The effects of fatigue loading frequency on fatigue life of high-strength pressure vessel steels  

NASA Astrophysics Data System (ADS)

Bend specimens of high-strength pressure vessel steel were tested in bending fatigue to failure at 1.5, 15, 30, arid 75 Hz fatigue loading frequencies. In the 1.5 to 15 Hz range, there was no discernible difference in the frequency effect on fatigue life. However, in the 30 to 75 Hz range, there was a definite increase in fatigue life compared to the lower range of frequency. The average increase in fatigue over the stress range was a factor of 10 greater than the life at the lower frequency range. This factor increased at lower stresses decreased at higher stresses, but even at the highest stresses tested, the increase was significant, about 5 to 1. This indicates that the frequency effect is more effective at high-cycle fatigue and diminishes with low-cycle fatigue. A model for fatigue life deterioration caused by superimposition of loads under different frequencies is introduced.

Fujczak, Robert R.

1994-06-01

140

Condition health monitoring of composite wound pressure vessels using fiber Bragg gratings  

NASA Astrophysics Data System (ADS)

Structure health monitoring refers to a real time and in situ monitoring system. It can diagnose the condition status of composite structure in time and effectively estimate the safety, increasing the reliability, extending the service life, at the same time, reducing the maintenance cost. In this paper, the sensing technology based on FBG sensors is employed to monitor the health of composite wound pressure vessel in service. Strain monitoring of the vessel in fatigue tests is carried out with the surface mounted FBG sensors. The experiment result shows that FBG sensors have several excellent performances: it has anti-fatigue capability to accurately measure the cycle strain; it is linear with the inner pressure and can be used as pressure sensor; the wavelength is diverged in the high stress gradient field, so the FBG can be used to measure the non-homogeneous strain field. Based on the fatigue damage mechanism of composite laminates and stiffness degradation model, the variation regularity of cycle strain of composite pressure vessel is studied and the residual stiffness during damage is obtained.

Zhang, Xiaojing; Zhang, Boming; Wu, Zhanjun

2007-10-01

141

Coevolution of solid stress and interstitial fluid pressure in tumors during progression: implications for vascular collapse.  

PubMed

The stress harbored by the solid phase of tumors is known as solid stress. Solid stress can be either applied externally by the surrounding normal tissue or induced by the tumor itself due to its growth. Fluid pressure is the isotropic stress exerted by the fluid phase. We recently showed that growth-induced solid stress is on the order of 1.3 to 13.0 kPa (10-100 mmHg)--high enough to cause compression of fragile blood vessels, resulting in poor perfusion and hypoxia. However, the evolution of growth-induced stress with tumor progression and its effect on cancer cell proliferation in vivo is not understood. To this end, we developed a mathematical model for tumor growth that takes into account all three types of stresses: growth-induced stress, externally applied stress, and fluid pressure. First, we conducted in vivo experiments and found that growth-induced stress is related to tumor volume through a biexponential relationship. Then, we incorporated this information into our mathematical model and showed that due to the evolution of growth-induced stress, total solid stress levels are higher in the tumor interior and lower in the periphery. Elevated compressive solid stress in the interior of the tumor is sufficient to cause the collapse of blood vessels and results in a lower growth rate of cancer cells compared with the periphery, independently from that caused by the lack of nutrients due to vessel collapse. Furthermore, solid stress in the periphery of the tumor causes blood vessels in the surrounding normal tissue to deform to elliptical shapes. We present histologic sections of human cancers that show such vessel deformations. Finally, we found that fluid pressure increases with tumor growth due to increased vascular permeability and lymphatic impairment, and is governed by the microvascular pressure. Crucially, fluid pressure does not cause vessel compression of tumor vessels. PMID:23633490

Stylianopoulos, Triantafyllos; Martin, John D; Snuderl, Matija; Mpekris, Fotios; Jain, Saloni R; Jain, Rakesh K

2013-04-30

142

Fabrication Flaws in Reactor Pressure Vessel Repair Welds  

SciTech Connect

This paper describes the fabrication flaw distribution and characterization in the repair weld metal of reactor pressure vessels. This work indicates that the large flaws occur in these repairs. These results show that repair flaws are complex in composition and sometimes include cracks on the repair ends. Parametric analysis using an exponential fit is performed on the data. A description of repair flaw morphology is provided. Fabrication flaws in repairs are characterized using high sensitivity nondestructive ultrasonic testing, validation by other nondestructive evaluation (NDE) techniques, and complemented by destructive testing.

Schuster, George J.; Doctor, Steven R.

2007-12-01

143

Steel-concrete combination element for lining vessels such as storage tanks, prestressed concrete reactor pressure vessels, and the like  

Microsoft Academic Search

Compound elements are disclosed for lining such vessels as storage tanks, prestressed concrete reactor pressure vessels, and other gastight areas for use in nuclear reactor construction. The compound elements have a leakproof, plate-shaped metal base, and comprise anchors, contact elements, and reinforced concrete. The contact elements and base of one compound element are welded to a contact element and the

H. Sturmer; K. Schweim

1977-01-01

144

Non-Invasive Method and Apparatus for Measuring Pressure within a Pliable Vessel.  

National Technical Information Service (NTIS)

A non-invasive method and apparatus for measuring pressure within a pliable vessel such as a blood vessel are described. The blood vessel is clamped by means of a clamping structure having a first portion housing a pressure sensor, and a second portion ex...

M. Shimizu

1981-01-01

145

Performance Evaluation Tests of Insulated Pressure Vessels for Vehicular Hydrogen Storage  

Microsoft Academic Search

Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen or ambient-temperature compressed hydrogen. This flexibility results in multiple advantages with respect to compressed hydrogen tanks or low-pressure liquid hydrogen tanks. Our work is directed at verifying that commercially available aluminum-lined, fiber-wrapped pressure vessels can be safely used to store liquid hydrogen. A series of tests

S M Aceves; J Martinez-Frias; F Espinoza-Loza

2002-01-01

146

Certification Testing and Demonstration of Insulated Pressure Vessels for Vehicular Hydrogen Storage  

Microsoft Academic Search

Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen or ambient-temperature compressed hydrogen. This flexibility results in multiple advantages with respect to compressed hydrogen tanks or low-pressure liquid hydrogen tanks. Our work is directed at verifying that commercially available aluminum-lined, fiber-wrapped pressure vessels can be safely used to store liquid hydrogen. A series of tests

S M Aceves; J Martinez-Frias; F Espinosa-Loza

2002-01-01

147

Influence of crack depth on the fracture toughness of reactor pressure vessel steel  

SciTech Connect

The Heavy Section Steel Technology Program (HSST) at Oak Ridge National Laboratory (ORNL) is investigating the influence of flaw depth on the fracture toughness of reactor pressure vessel (RPV) steel. Recently, it has been shown that, in notched beam testing, shallow cracks tend to exhibit an elevated toughness as a result of a loss of constraint at the crack tip. The loss of constraint takes place when interaction occurs between the elastic-plastic crack-tip stress field and the specimen surface nearest the crack tip. An increased shallow-crack fracture toughness is of interest to the nuclear industry because probabilistic fracture-mechanics evaluations show that shallow flaws play a dominant role in the probability of vessel failure during postulated pressurized-thermal-shock (PTS) events. Tests have been performed on beam specimens loaded in 3-point bending using unirradiated reactor pressure vessel material (A533 B). Testing has been conducted using specimens with a constant beam depth (W = 94 mm) and within the lower transition region of the toughness curve for A533 B. Test results indicate a significantly higher fracture toughness associated with the shallow flaw specimens compared to the fracture toughness determined using deep-crack (a/W = 0.5) specimens. Test data also show little influence of thickness on the fracture toughness for the current test temperature ({minus}60{degree}C). 21 refs., 5 figs., 3 tabs.

Theiss, T.J.; Bryson, J.W.

1991-01-01

148

77 FR 16270 - Updated Aging Management Criteria for Reactor Vessel Internal Components of Pressurized Water...  

Federal Register 2010, 2011, 2012, 2013

...Management Criteria for Reactor Vessel Internal Components of Pressurized Water Reactors AGENCY: Nuclear Regulatory...Management Criteria for PWR Reactor Vessel Internal Components...exposed to treated borated water. DATES: Submit...

2012-03-20

149

77 FR 23513 - Updated Aging Management Criteria for Reactor Vessel Internal Components of Pressurized Water...  

Federal Register 2010, 2011, 2012, 2013

...Updated Aging Management Criteria for Reactor Vessel Internal Components of Pressurized Water Reactors AGENCY: Nuclear Regulatory Commission...Updated Aging Management Criteria for PWR Reactor Vessel Internal Components.'' The...

2012-04-19

150

Round robin analysis for probabilistic structural integrity of reactor pressure vessel under pressurized thermal shock  

Microsoft Academic Search

Performed here is a comparative assessment study for the probabilistic fracture mechanics approach of the pressurized thermal\\u000a shock of the reactor pressure vessel A round robin consisting of one prerequisite deterministic study and five cases for probabilistic\\u000a approaches is proposed, and all organizations interested are invited The problems are solved by the paiticipants and their\\u000a results are compared to issue

Myung Jo Jhung; Changheui Jang; Seok Hun Kim; Young Hwan Choi; Hho Jung Kim; Sunggyu Jung; Jong Min Kim; Gap Heon Sohn; Tae Eun Jin; Taek Sang Choi; Ji Ho Kim; Jong Wook Kim; Keun Bae Park

2005-01-01

151

A Review of Large-Scale Fracture Experiments Relevant to Pressure Vessel Integrity Under Pressurized Thermal Shock Conditions  

Microsoft Academic Search

Numerous large-scale fracture experiments have been performed over the past thirty years to advance fracture mechanics methodologies applicable to thick-wall pressure vessels. This report first identifies major factors important to nuclear reactor pressure vessel (RPV) integrity under pressurized thermal shock (PTS) conditions. It then covers 20 key experiments that have contributed to identifying fracture behavior of RPVs and to validating

C. E. Pugh; B. R. Bass

2001-01-01

152

Role of Crack Arrest in the Evaluation of PWR Pressure Vessel Integrity During PTS Transients.  

National Technical Information Service (NTIS)

The PWR pressurized thermal-shock (PTS) issue, which is concerned with the integrity of the reactor pressure vessel during postulated overcooling transients, is under intensive investigation by the USNRC. The USNRC-sponsored Integrated Pressurized Thermal...

R. D. Cheverton D. G. Ball

1984-01-01

153

46 CFR 54.01-10 - Steam-generating pressure vessels (modifies U-1(g)).  

Code of Federal Regulations, 2010 CFR

...U-1(g)). (a) Pressure vessels in which steam...fitted with an efficient water level indicator, a pressure gage, a blowdown valve...fitted with an efficient water level indicator, a pressure gage, and a blowdown...

2010-10-01

154

46 CFR 54.01-10 - Steam-generating pressure vessels (modifies U-1(g)).  

Code of Federal Regulations, 2010 CFR

...U-1(g)). (a) Pressure vessels in which steam...fitted with an efficient water level indicator, a pressure gage, a blowdown valve...fitted with an efficient water level indicator, a pressure gage, and a blowdown...

2009-10-01

155

Some mechanistic observations on the crack growth characteristics of pressure vessel and piping steels in PWR environment  

Microsoft Academic Search

The fatigue crack growth behavior of A533B and A508 pressure vessel steel and AISI Types 304 and 316 steels used in reactor coolant piping have been studied in a pressurized water reactor environment at 288°C (550°F). The influence of stress ratio (P\\/sub min\\/\\/P\\/sub max\\/), frequency, ramp times, specimen orientation and material microstructures were included in the study. While none of

W. H. Bamford; D. M. Moon

1979-01-01

156

D-Zero Central Calorimeter Pressure Vessel and Vacuum Vessel Safety Notes  

SciTech Connect

The relief valve and relief piping capacity was calculated to be 908 sefm air. This exceeds all relieving conditions. The vessel also has a rupture disc with a 2640 scfm air stamped capacity. In order to significantly decrease the amount of time required to fill the cryostats, it is desired to raise the setpoint of the 'operating' relief valve on the argon storage dewar to 20 psig from its existing 16 psig setting. This additional pressure increases the flow to the cryostats and will overwhelm the relief capacity if the temperature of the modules within these vessels is warm enough. Using some conservative assumptions and simple calculations within this note, the maximum average temperature that the modules within each cryostat can be at prior to filling from the storage dewar with liquid argon is at least 290 K. The average temperature of the module mass for any of the three cryostats can be as high as 290 K prior to filling that particular cryostat. This should not be confused with the average temperature of a single type or location which is useful in protecting the modules-not necessarily the vessel itself. A few modules of each type and at different elevations should be used in an average which would account for the different weights of each module. Note that at 290 K, the actual flow of argon through the relief valve and the rupture disk was under the maximum theoretical flows for each relief device. This means that the bulk temperature could actually have been raised to flow argon through the reliefs at their maximum capacity. Therefore, the temperature of 290 K is a conservative value for the calculated flow rate of 12.3 gpm. Safeguards in addition to and used in conjunction with operating procedures shall be implemented in such a way so that the above temperature limitation is not exceeded and such that it is exclusive of the programmable logic controller (PLC). One suggestion is using a toggle switch for each cryostat mounted in the PLC I/O box which would maintain control of the signals to open the cold fill valves of each cryostat. With the safeguards in place while carefully monitoring the temperatures during a cooldown cycle in each cryostat, the set pressure in the argon storage dewar can safely be increased to 20 psig.

Rucinski, R.; Luther, R.; /Fermilab

1990-10-25

157

ASTM Standards for Reactor Dosimetry and Pressure Vessel Surveillance  

SciTech Connect

The ASTM standards provide guidance and instruction on how to field and interpret reactor dosimetry. They provide a roadmap towards understanding the current ''state-of-the-art'' in reactor dosimetry, as reflected by the technical community. The consensus basis to the ASTM standards assures the user of an unbiased presentation of technical procedures and interpretations of the measurements. Some insight into the types of standards and the way in which they are organized can assist one in using them in an expeditious manner. Two example are presented to help orient new users to the breadth and interrelationship between the ASTM nuclear metrology standards. One example involves the testing of a new ''widget'' to verify the radiation hardness. The second example involves quantifying the radiation damage at a pressure vessel critical weld location through surveillance dosimetry and calculation.

GRIFFIN, PATRICK J.

1999-09-14

158

Pressurized thermal shock probabilistic fracture mechanics sensitivity analysis for Yankee Rowe reactor pressure vessel  

SciTech Connect

The Nuclear Regulatory Commission (NRC) requested Oak Ridge National Laboratory (ORNL) to perform a pressurized-thermal-shock (PTS) probabilistic fracture mechanics (PFM) sensitivity analysis for the Yankee Rowe reactor pressure vessel, for the fluences corresponding to the end of operating cycle 22, using a specific small-break-loss- of-coolant transient as the loading condition. Regions of the vessel with distinguishing features were to be treated individually -- upper axial weld, lower axial weld, circumferential weld, upper plate spot welds, upper plate regions between the spot welds, lower plate spot welds, and the lower plate regions between the spot welds. The fracture analysis methods used in the analysis of through-clad surface flaws were those contained in the established OCA-P computer code, which was developed during the Integrated Pressurized Thermal Shock (IPTS) Program. The NRC request specified that the OCA-P code be enhanced for this study to also calculate the conditional probabilities of failure for subclad flaws and embedded flaws. The results of this sensitivity analysis provide the NRC with (1) data that could be used to assess the relative influence of a number of key input parameters in the Yankee Rowe PTS analysis and (2) data that can be used for readily determining the probability of vessel failure once a more accurate indication of vessel embrittlement becomes available. This report is designated as HSST report No. 117.

Dickson, T.L.; Cheverton, R.D.; Bryson, J.W.; Bass, B.R.; Shum, D.K.M.; Keeney, J.A. [Oak Ridge National Lab., TN (United States)

1993-08-01

159

The behavior of shallow flaws in reactor pressure vessels  

SciTech Connect

Both analytical and experimental studies have shown that the effect of crack length, a, on the elastic-plastic toughness of structural steels is significant. The objective of this report is to recommend those research investigations that are necessary to understand the phenomenon of shallow behavior as it affects fracture toughness so that the results can be used properly in the structural margin assessment of reactor pressure vessels (RPVs) with flaws. Preliminary test results of A 533 B steel show an elevated crack-tip-opening displacement (CTOD) toughness similar to that observed for structural steels tested at the University of Kansas. Thus, the inherent resistance to fracture initiation of A 533 B steel with shallow flaws appears to be higher than that used in the current American Society of Mechanical Engineers (ASME) design curves based on testing fracture mechanics specimens with deep flaws. If this higher toughness of laboratory specimens with shallow flaws can be transferred to a higher resistance to failure in RPV design or analysis, then the actual margin of safety in nuclear vessels with shallow flaws would be greater than is currently assumed on the basis of deep-flaw test results. This elevation in toughness and greater resistance to fracture would be a very desirable situation, particularly for the pressurized-thermal shock (PTS) analysis in which shallow flaws are assumed to exist. Before any advantage can be taken of this possible increase in initiation toughness, numerous factors must be analyzed to ensure the transferability of the data. This report reviews those factors and makes recommendations of studies that are needed to assess the transferability of shallow-flaw toughness test results to the structural margin assessment of RPV with shallow flaws. 14 refs., 8 figs.

Rolfe, S.T. (Kansas Univ., Lawrence, KS (United States))

1991-11-01

160

CYCLIC PRESSURE TESTS OF LARGE SIZE PRESSURE VESSELS. Progress Report No. 1, October 15, 1962 to January 15, 1963  

Microsoft Academic Search

Activities in a program to study the effects of welding defects on low-; cycle fatigue of pressure vessels are reported. The vessels under study have 36-; in. ID and 2-in. wall thicknesses, and contain nozzles of various designs and ; sizes. A cylindrical portion of vessel #4 was removed by flame cutting and ; replaced by welding; cyclic testing is

A. G. Pickett; J. D. Michie

1963-01-01

161

Evidence of Increased Oxidative Stress in Aged Mesenteric Lymphatic Vessels  

PubMed Central

Abstract Background We have previously shown that aging is associated with weakened rat mesenteric lymphatic vessel (MLV) contractility. However, the specific mechanisms contributing to this aging-associated contractile degeneration remain unknown. Aging is often associated with elevations in oxidative stress, and reactive oxygen species (ROS) have been shown to reduce the contractility of MLV. Thus in the present study, we sought to assess whether aging is associated with increased levels of oxidative stress and oxidative damage in MLV. Methods and Results MLV were isolated from 9-mo- and 24-mo-old Fischer-344 rats and subjected to the following experimental techniques: measurement of total superoxide dismutase (SOD) activity; estimation of lipid peroxidation levels via measurement of thiobarbituric acid reactive substances (TBARS); detection of superoxide and mitochondrial ROS in live MLV; Western blot analysis, and immunohistochemical labeling of the SOD isoforms and nitro-tyrosine proteins. We found that aging is associated with increased levels of cellular superoxide and mitochondrial ROS concomitant with a reduction in Cu/Zn-SOD protein expression and total SOD enzymatic activity in MLV. This increase in oxidative stress and decrease in antioxidant activity was associated with evidence of increased lipid (as indicated by TBARS) and protein (as indicated by nitro-tyrosine labeling) oxidative damage. Conclusions Thus for the first time, we demonstrate that aging-associated increases in oxidative stress and oxidative damage is indeed present in the walls of MLV and may contribute to the aging-associated lymphatic pump dysfunction we previously reported.

Thangaswamy, Sangeetha; Bridenbaugh, Eric A.

2012-01-01

162

Microorganism inactivation using high-pressure generation in sealed vessels under sub-zero temperature  

Microsoft Academic Search

In order to test the possibility of utilizing high pressure in bioscience and biotechnology, a simple method for high-pressure\\u000a generation and its use for microbial inactivation have been studied. When a pressure vessel was filled with water, sealed\\u000a tightly and cooled to sub-zero temperatures, high pressure was generated in the vessel. The pressure generation was 60?MPa\\u000a at ?5?C, 103?MPa at

K. Hayakawa; Y. Ueno; S. Kawamura; T. Kato; R. Hayashi

1998-01-01

163

Deformation behavior in reactor pressure vessel steels as a clue to understanding irradiation hardening.  

SciTech Connect

In this paper, we examine the post-yield true stress vs true strain behavior of irradiated pressure vessel steels and iron-based alloys to reveal differences in strain-hardening behavior associated with different irradiating particles (neutrons and electrons) and different alloy chernky. It is important to understand the effects on mechanical properties caused by displacement producing radiation of nuclear reactor pressure steels. Critical embrittling effects, e.g. increases in the ductile-to-brittle-transition-temperature, are associated with irradiation-induced increases in yield strength. In addition, fatigue-life and loading-rate effects on fracture can be related to the post-irradiation strain-hardening behavior of the steels. All of these properties affect the expected service life of nuclear reactor pressure vessels. We address the characteristics of two general strengthening effects that we believe are relevant to the differing defect cluster characters produced by neutrons and electrons in four different alloys: two pressure vessel steels, A212B and A350, and two binary alloys, Fe-0.28 wt%Cu and Fe-0.74 wt%Ni. Our results show that there are differences in the post-irradiation mechanical behavior for the two kinds of irradiation and that the differences are related both to differences in damage produced and alloy chemistry. We find that while electron and neutron irradiations (at T {le} 60 C) of pressure vessel steels and binary iron-based model alloys produce similar increases in yield strength for the same dose level, they do not result in the same post-yield hardening behavior. For neutron irradiation, the true stress flow curves of the irradiated material can be made to superimpose on that of the unirradiated material, when the former are shifted appropriately along the strain axis. This behavior suggests that neutron irradiation hardening has the same effect as strain hardening for all of the materials analyzed. For electron irradiated steels, the post-yield hardening rate is clearly greater than that of the unirradiated material, and the flow curves cannot be made to superimpose. The binary iron-base model alloys studied here show a less pronounced difference in flow behavior for neutrons and electrons than exhibited by the steels, implicating the effect of alloy chemistry. Our results are analyzed in the context of classical theories dealing with the interaction between the deformation microstructure, i.e. glide dislocations, and irradiation-produced defects. Our findings provide clues about the way different alloy constituents interact with the different kinds of irradiation damage to strengthen the material differently.

DiMelfi, R. J.; Alexander, D. E.; Rehn, L. E.

1999-10-25

164

Detection and characterization of indications in segments of reactor pressure vessels  

Microsoft Academic Search

Studies have been conducted to estimate flaw density in segments cut from light water reactor (LWR) pressure vessels as part of the Oak Ridge National Laboratory's Heavy-Section Steel Technology (HSST) Program. Segments from the Hope Creek Unit 2 vessel and the Pilgrim Unit 2 vessel were purchased from salvage dealers. Hope Creek was a boiling water reactor (BWR) design and

K. V. Cook; R. A. Jr. Cunningham; R. W. McClung

1989-01-01

165

Stress concentration factors of flat end to cylindrical shell connection with a fillet or stress relief groove subjected to internal pressure  

Microsoft Academic Search

For fatigue assessment of pressure vessels (parts), as proposed by the CEN Technical Committee 54, the knowledge of some stress quantities in the structure is necessary, e.g. equivalent stresses according to Tresca's yield criterion and principal stresses at welds. In this article, these quantities are given in the form of stress concentration factors for the flat end to cylindrical shell

Reinhard Preiss

1997-01-01

166

Robust stress-classification of pressure components using the GLOSS and GLOSS r-node methods  

SciTech Connect

The GLOSS and GLOSS r-mode methods are used to classify stresses in pressure components. The classification scheme is akin to the prevailing ASME Boiler and Pressure Vessel Code procedures. The proposed method is applied to a cylinder flat-head configuration for thin as well as thick heads, and the stress classification methodology is outlined. The methods described in this paper can be readily applied to a general three-dimensional pressure component configuration.

Seshadri, R. [Memorial Univ. of Newfoundland, St. John`s (Canada). Faculty of Engineering and Applied Science

1996-05-01

167

Design of Semi-composite Pressure Vessel using Fuzzy and FEM  

Microsoft Academic Search

The present study attempts to present a new method to design a semi-composite pressure vessel (known as hoop-wrapped composite\\u000a cylinder) using fuzzy decision making and finite element method. A metal-composite vessel was designed based on ISO criteria\\u000a and then the weight of the vessel was optimized for various fibers of carbon, glass and Kevlar in the cylindrical vessel.\\u000a Failure criteria

Mohammad H. Sabour; Mohammad F. Foghani

2010-01-01

168

Design of Semi-composite Pressure Vessel using Fuzzy and FEM  

Microsoft Academic Search

The present study attempts to present a new method to design a semi-composite pressure vessel (known as hoop-wrapped composite cylinder) using fuzzy decision making and finite element method. A metal-composite vessel was designed based on ISO criteria and then the weight of the vessel was optimized for various fibers of carbon, glass and Kevlar in the cylindrical vessel. Failure criteria

Mohammad H. Sabour; Mohammad F. Foghani

2010-01-01

169

Failure analysis of a pressure vessel bolt in a nuclear fuel fretting wear simulator  

Microsoft Academic Search

This paper presents a failure analysis on a pressure vessel bolt of a fretting wear simulator. After 500h tests, in an upper pressure vessel of a fretting wear simulator, one bolt among eight was fractured near the bolt neck regions. The fracture surface was examined by using a scanning electron microscope (SEM) to determine the failure initiation and failure mode.

Young-Ho Lee; Hyung-Kyu Kim

2011-01-01

170

Deterministic assessment of reactor pressure vessel integrity under pressurised thermal shock  

Microsoft Academic Search

Numerical investigations were carried out to assess the integrity of reactor pressure vessels under pressurised thermal shock (PTS). The 4-loop reactor pressure vessel with cladding was subjected to thermo-mechanical loading owing to loss of coolant accident. The loss of coolant accident corresponding to small break as well as hot leg breaks were considered separately, which led to axisymmetric and asymmetric

N. K Mukhopadhyay; T. V Pavan Kumar; J Chattopadhyay; B. K Dutta; H. S Kushwaha; V Venkat Raj

1998-01-01

171

Statistical Analysis of Reactor Pressure Vessel Fluence Calculation Benchmark Data Using Multiple Regression Techniques  

Microsoft Academic Search

The calculated >1-MeV pressure vessel fluence is used to determine the fracture toughness and integrity of the reactor pressure vessel. It is therefore of the utmost importance to ensure that the fluence prediction is accurate and unbiased. In practice, this assurance is provided by comparing the predictions of the calculational methodology with an extensive set of accurate benchmarks. A benchmarking

John F. Carew; Stephen J. Finch; Lambros Lois

2003-01-01

172

Dual shell reactor vessel: A pressure-balanced system for high pressure and temperature reactions  

SciTech Connect

The main purpose of this work was to demonstrate the Dual Shell Pressure Balanced Vessel (DSPBV) as a safe and economical reactor for the hydrothermal water oxidation of hazardous wastes. Experimental tests proved that the pressure balancing piston and the leak detection concept designed for this project will work. The DSPBV was sized to process 10 gal/hr of hazardous waste at up to 399{degree}C (750{degree}F) and 5000 psia (34.5 MPa) with a residence time of 10 min. The first prototype reactor is a certified ASME pressure vessel. It was purchased by Innotek Corporation (licensee) and shipped to Pacific Northwest Laboratory for testing. Supporting equipment and instrumentation were, to a large extent, transported here from Battelle Columbus Division. A special air feed system and liquid pump were purchased to complete the package. The entire integrated demonstration system was assembled at PNL. During the activities conducted for this report, the leak detector design was tested on bench top equipment. Response to low levels of water in oil was considered adequate to ensure safety of the pressure vessel. Shakedown tests with water only were completed to prove the system could operate at 350{degree}C at pressures up to 3300 psia. Two demonstration tests with industrial waste streams were conducted, which showed that the DSPBV could be used for hydrothermal oxidation. In the first test with a metal plating waste, chemical oxygen demand, total organic carbon, and cyanide concentrations were reduced over 90%. In the second test with a munitions waste, the organics were reduced over 90% using H{sub 2}O{sub 2} as the oxidant.

Robertus, R.J.; Fassbender, A.G.; Deverman, G.S.

1995-03-01

173

Coordinated sensing and autonomous repair of pressure vessels and structures  

NASA Astrophysics Data System (ADS)

Self-repairing structural systems can potentially improve performance ranges and lifetimes compared to those of conventional systems without self-healing capability. Self-healing materials have been used in automotive and aeronautical applications for over a century. The bulk of these systems operate by using the damage to directly initiate the repair response without any supervisory coordination. Integrating sensing and supervisory control technologies with self-healing may improve the safety and reliability of critical components and structures. This project used laboratory scale test beds to illustrate the benefit of an integrated sensing, control and self-healing system. A thermal healing polymer embedded with resistive heating wires acted as the sensing-healing material. Sensing duties were performed using an impedance, capacitance, and resistance testing device and a PC acted as the controller. As damage occurs to the polymer it is detected, located, and characterized. Based on the sensor signal, a decision is made as to whether to execute a repair and then to subsequently monitor the repair process to ensure completeness. The second demonstration was a self-sealing pressure vessel with integrated sensing and healing capability. These proof-of-concept prototypes can likely be expanded and improved with alternative sensor options, sensing-healing materials, and system architecture.

Huston, Dryver R.; Hurley, David A.; Gollins, Kenneth; Gervais, Anthony

2010-03-01

174

Advances in crack-arrest technology for reactor pressure vessels  

SciTech Connect

The Heavy-Section Steel Technology (HSST) Program at the Oak Ridge National Laboratory (ORNL) under the sponsorship of the US Nuclear Regulatory Commission is continuing to improve the understanding of conditions that govern the initiation, rapid propagation, arrest, and ductile tearing of cracks in reactor pressure vessel (RPV) steels. This paper describes recent advances in a coordinated effort being conducted under the HSST Program by ORNL and several subcontracting groups to develop the crack-arrest data base and the analytical tools required to construct inelastic dynamic fracture models for RPV steels. Large-scale tests are being carried out to generate crack-arrest toughness data at temperatures approaching and above the onset of Charpy upper-shelf behavior. Small- and intermediate-size specimens subjected to static and dynamic loading are being developed and tested to provide additional fracture data for RPV steels. Viscoplastic effects are being included in dynamic fracture models and computer programs and their utility validated through analyses of data from carefully controlled experiments. Recent studies are described that examine convergence problems associated with energy-based fracture parameters in viscoplastic-dynamic fracture applications. Alternative techniques that have potential for achieving convergent solutions for fracture parameters in the context of viscoplastic-dynamic models are discussed. 46 refs., 15 figs., 3 tabs.

Bass, B.R.; Pugh, C.E.

1988-01-01

175

Pressure vessel steel embrittlement monitoring by magnetic properties measurements  

SciTech Connect

The magnetic properties of specimens of one heat of A533B nuclear pressure vessel grade steel have been examined in the as-received condition and after neutron irradiation to various fluence levels up to 4 [times] 10[sup 18] cm[sup [minus]2] (E > 0.1 MeV) in the University of Illinois Advanced TRIGA reactor core at two temperatures, approximately 120 and 260[degrees]C. The effect of some heat treatments was also investigated. The magnetic properties were measured by an automated hysteresis curve tracing method using a miniature transformer which incorporated the specimens in its core. Changes in magnetic hysteresis energy loss were correlated with neutron fluence in the case of certain irradiated specimens, and with microhardness measurements in the case of heat treated specimens. At the higher irradiation temperatures, no significant changes in either the magnetic hysteresis properties or the microhardness were noted for the present fluences. The relationship between the observed magnetic properties response and irradiation-induced embrittlement is discussed.

Stubbins, J.F.; Shong, W-J.; Giacobbe, M.; Ougouag, A.M. (Illinois Univ., Urbana, IL (United States). Dept. of Nuclear Engineering); Williams, J.G. (Arizona Univ., Tucson, AZ (United States). Dept. of Nuclear Engineering)

1992-01-01

176

Pressure vessel steel embrittlement monitoring by magnetic properties measurements  

SciTech Connect

The magnetic properties of specimens of one heat of A533B nuclear pressure vessel grade steel have been examined in the as-received condition and after neutron irradiation to various fluence levels up to 4 {times} 10{sup 18} cm{sup {minus}2} (E > 0.1 MeV) in the University of Illinois Advanced TRIGA reactor core at two temperatures, approximately 120 and 260{degrees}C. The effect of some heat treatments was also investigated. The magnetic properties were measured by an automated hysteresis curve tracing method using a miniature transformer which incorporated the specimens in its core. Changes in magnetic hysteresis energy loss were correlated with neutron fluence in the case of certain irradiated specimens, and with microhardness measurements in the case of heat treated specimens. At the higher irradiation temperatures, no significant changes in either the magnetic hysteresis properties or the microhardness were noted for the present fluences. The relationship between the observed magnetic properties response and irradiation-induced embrittlement is discussed.

Stubbins, J.F.; Shong, W-J.; Giacobbe, M.; Ougouag, A.M. [Illinois Univ., Urbana, IL (United States). Dept. of Nuclear Engineering; Williams, J.G. [Arizona Univ., Tucson, AZ (United States). Dept. of Nuclear Engineering

1992-12-01

177

HFIR (High Flux Isotope Reactor) pressure vessel and structural components materials surveillance program: Supplement 1  

SciTech Connect

Extending the life of the HFIR vessel by the proposed 10 effective full-power years is contingent upon a continuation of the materials surveillance program and the application of hydrostatic proof testing. As a part of the surveillance program, Charpy V-notch (CVN) specimens of shell, weld and nozzle materials are installed adjacent to the inner surface of the vessel and are removed periodically for testing to determine the radiation-induced increase in the nil-ductility transition temperature. Hydro testing is conducted to prove that a critical combination of flaw size, stress and fracture toughness does not exist. Information from the materials surveillance program is used in a fracture mechanics analysis to confirm that the hydro-test pressure being applied is appropriate for the desired life extension of the vessel. This report specifies (1) the number, type, location and schedule for removal-testing of the CVN specimens for the continuing materials surveillance program, and (2) the procedures and test conditions for the hydro test.

Cheverton, R.D.; McGinty, D.M.; McWherter, J.R.; Nanstad, R.K.

1987-10-01

178

Experimental investigation into water-filled pressurized vessels damaged by high-velocity projectile impact  

NASA Astrophysics Data System (ADS)

All spacecraft in orbit are susceptible to high velocity impact by meteoroid and space debris. Pressure vessels are the most critical components onboard spacecraft. Impacts of meteoroid or space debris on pressure vessels can indeed lead to the rupturing failure of the vessel and terminate prematurely spacecraft mission. The aim of this work is to explore experimentally the condition and the limit between simple perforation and rupturing damage of pressure vessels under high velocity impacts. Preliminary results are presented from high-velocity impact tests on thin-walled aluminum and steel cylindrical pressurized vessels filled with different percent volume of water and different pressure of gas. Damage patterns and mechanisms leading to rupturing failure are discussed.

Pang, Baojun; Zhang, Wei; Luo, Dekun; Zhang, Zehua

2001-10-01

179

Factors affecting the integrity of PWR pressure vessels during overcooling accidents  

SciTech Connect

The reactor pressure vessel in a pressurized water reactor is normally subjected to temperatures and pressures that preclude propagation of sharp, crack-like defects that might exist in the wall of the vessel. However, if certain postulated accidents, referred to as overcooling accidents, were to occur, the pressure vessel could be subjected to severe thermal shock while the pressure is substantial. As a result, vessels containing high concentrations of copper and nickel, which enhance radiation embrittlement, may possess a potential for extensive propagation of preexistent inner-surface flaws prior to the vessel's normal end of life. A fracture-mechanics analysis for a typical postulated accident and also related thermal-shock experiments indicate that very shallow surface flaws that extend through the cladding into the base material could propagate. This is of particular concern because shallow flaws appear to be the most probable and presumably are the most difficult to detect.

Cheverton, R.D.

1983-01-01

180

Fundamental study of failure mechanisms of pressure vessels under thermo-mechanical cycling in multiphase environments  

NASA Astrophysics Data System (ADS)

Cracking and bulging in welded and internally lined pressure vessels that work in thermal-mechanical cycling services have been well known problems in the petrochemical, power and nuclear industries. Published literature and industry surveys show that similar problems have been occurring during the last 50 years. Understanding the causes of cracking and bulging would lead to improvements in the reliability of these pressure vessels. This study attempts to add information required for improving the knowledge and fundamental understanding of these problems. Cracking and bulging, most often in the weld areas, commonly experienced in delayed coking units (e.g. coke drums) in oil refineries are typical examples. The coke drum was selected for this study because of the existing field experience and past industrial investigation results that were available to serve as the baseline references for the analytical studies performed for this dissertation. Another reason for selecting the delayed coking units for this study was due to their high economical yields. Shutting down these units would cause a high negative economic impact on the refinery operations. Several failure mechanisms were hypothesized. The finite element method was used to analyze these significant variables and to verify the hypotheses. In conclusion, a fundamental explanation of the occurrence of bulging and cracking in pressure vessels in multiphase environments has been developed. Several important factors have been identified, including the high convection coefficient of the boiling layer during filling and quenching, the mismatch in physical, thermal and mechanical properties in the dissimilar weld of the clad plates and process conditions such as heating and quenching rate and warming time. Material selection for coke drums should consider not only fatigue strength but also corrosion resistance at high temperatures and low temperatures. Cracking occurs due to low cycle fatigue and corrosion. The FEA-subroutine process simulation was able to capture the important aspects of the thermo-mechanical cycle that influence the thermal and stress gradients in the shell.

Penso Mula, Jorge Antonio

181

Design of a standalone-type beryllium vessel for high-pressure protein crystallography  

NASA Astrophysics Data System (ADS)

A standalone-type beryllium (Be) high-pressure crystallography vessel has been developed. Using a coupler-joint unit and a pressure valve, we could keep the pressure in the vessel constant at 100+/-1 MPa for more than 24 h without connecting to a pressure-generating apparatus. Diffraction spots of a glucose isomerase (GI) crystal under 100 MPa were collected using the vessel and a rotating copper-anode in-house x-ray generator (0.8 kW). We successfully collected a 2.0 A? resolution data set of a 0.5 mm size GI crystal in an aqueous solution at 100 MPa.

Suzuki, Yoshihisa; Tsukamoto, Masayuki; Sakuraba, Haruhiko; Matsumoto, Masamitsu; Nagasawa, Makoto; Tamura, Katsuhiro

2010-08-01

182

Applications of energy-release-rate techniques to part-through cracks in experimental pressure vessels  

SciTech Connect

In nonlinear applications of computational fracture mechanics, energy release rate techniques are used increasingly for computing stress intensity parameters of crack configurations. Recently, deLorenzi used the virtual-crack-extension method to derive an analytical expression for the energy release rate that is better suited for three-dimensional calculations than the well-known J-integral. Certain studies of fracture phenomena, such as pressurized-thermal-shock of cracked structures, require that crack tip parameters be determined for combined thermal and mechanical loads. A method is proposed here that modifies the isothermal formulation of deLorenzi to account for thermal strains in cracked bodies. This combined thermo-mechanical formulation of the energy release rate is valid for general fracture, including nonplanar fracture, and applies to thermo-elastic as well as deformation plasticity material models. Two applications of the technique are described here. In the first, semi-elliptical surface cracks in an experimental test vessel are analyzed under elastic-plastic conditions using the finite element method. The second application is a thick-walled test vessel subjected to combined pressure and thermal shock loadings.

Bass, B.R.; Bryan, R.H.; Bryson, J.W.; Merkle, J.G.

1982-01-01

183

A survey of pressure vessel code compliance methods for superconducting radio frequency cryomodules  

NASA Astrophysics Data System (ADS)

Superconducting radio frequency (SRF) cavities made from niobium and cooled with liquid helium are becoming key components of many particle accelerators. The helium vessels surrounding the RF cavities, portions of the niobium cavities themselves, and also possibly the vacuum vessels containing these assemblies, generally fall under the scope of local and national pressure vessel codes. In the U.S., Department of Energy rules require national laboratories to follow national consensus pressure vessel standards or to show "a level of safety greater than or equal to" that of the applicable standard. Thus, while used for its superconducting properties, niobium ends up being treated as a low-temperature pressure vessel material. Niobium material is not a code listed material and therefore requires the designer to understand the mechanical properties for material used in each pressure vessel fabrication; compliance with pressure vessel codes therefore becomes a problem. This report summarizes the approaches that various institutions have taken in order to bring superconducting RF cryomodules into compliance with pressure vessel codes.

Peterson, Thomas J.; Hayano, Hitoshi; Jensch, Kay; Kako, Eiji; Klebaner, Arkadiy; Mammosser, John; Matheisen, Axel; Nakai, Hirotaka; Nicol, Thomas H.; Theilacker, Jay; Yamamoto, Akira

2012-06-01

184

The Mechanical Analysis of a New MultiChannel High-Pressure Vessel  

Microsoft Academic Search

With the rapid development of science and technology, high-pressure vessel has been widely used in petroleum, chemical industry, aerospace, and pharmaceutical areas, and is the key equipment in these areas, and its structure increasing size, operating pressure and operating temperature getting higher and higher, and thus the design of pressure vessels have become increasingly demanding. This type of multi-channel single-cylinder

Xuefei Qiao; Bin Wang; Wen Liu; Junfeng Yang

2010-01-01

185

Response of a LWR pressure vessel to severe-accident loadings  

SciTech Connect

In the recent emphasis on nuclear safety, structural studies of nuclear reactor vessels have been directed toward evaluating their response during severe loading incidents or accidents including even core meltdown - however improbable these accidents may be. The present paper will address some of these problems. The ultimate load carrying capacity of an unflawed nuclear pressure vessel is estimated. The measure of the maximum pressure that the vessel can resist during quasistatic loading is a useful quantitative estimate of overall vessel strength. The paper than analyzes two structural problems during a hypothetical meltdown. In the initial stage, the molten core mixture drops into the lower portion of the pressure vessel, resulting in both temperature and pressure rises. Subsequently, a vapor explosion may occur as a result of the molten metal coming in sudden contact with the water in the lower portion of the vessel. The explosion is postulated to propel a slug of molten metalup the vessel barrel that eventually impacts the upper head of the vessel potentially generating missiles in the containment building. The reactor vessel at Indian Point, New York is used as a prototype of this analysis.

Ju, F.D.; Bennett, J.G.; Anderson, C.A.

1982-01-01

186

Elastostatic stress fields from pressurized cavities  

Microsoft Academic Search

The elastostatic version of the null field approach is applied to the problem of computing the stress field around one or\\u000a more pressurized cavities. The translation properties of the spherical solutions to the elastostatic equation of equilibrium\\u000a are derived, and it is shown how to compute stresses also inside the circumscribing spheres of the cavities.

Peter Olsson

1985-01-01

187

HFIR Pressure Vessel and Structural Components Materials Surveillance Program  

SciTech Connect

A proposal has been made to increase the size of the HFIR HB-2 and HB-4 beam tubes and to extend the life of the vessel to 50 EFPY(100 MW). Studies indicate that the increase in radiation-induced embrittlement of the vessel can be tolerated, and an appropriate expanded vessel-materials surveillance program has been devised. This program, which is the subject of this report, includes additional beam-tube nozzle-material surveillance specimens, relocation of existing specimens of all materials, and additional dosimetry. As an aid in the placement of specimens and dosimeters, extensive two- and three-dimensional neutron and gamma flux/dpa transport calculations were made. Surveillance data will be added to the HFIR vessel (delta)NDTT vs dpa data base, and dosimetry will be used to normalize the calculated fluxes. The updated (delta)NDTT vs dpa correlation and the normalized dpa values will be used in the calculation of the probability of vessel failure. This procedure, in conjunction with periodic hydrostatic proof testing, is used to determine the useful life of the vessel.

Blakeman, E.D.; Cheverton, R.D.; Nanstad, R.K.

1999-08-01

188

Programmable calculator stress analysis  

SciTech Connect

Advanced programmable alphanumeric calculators are well suited for closed-form calculation of pressure-vessel stresses. They offer adequate computing power, portability, special programming features, and simple interactive execution procedures. Representative programs that demonstrate calculator capabilities are presented. Problems treated are stress and strength calculations in thick-walled pressure vessels and the computation of stresses near head/pressure-vessel junctures.

Van Gulick, L.A.

1983-01-01

189

DEVELOPMENT OF ASME SECTION X CODE RULES FOR HIGH PRESSURE COMPOSITE HYDROGEN PRESSURE VESSELS WITH NON-LOAD SHARING LINERS  

SciTech Connect

The Boiler and Pressure Vessel Project Team on Hydrogen Tanks was formed in 2004 to develop Code rules to address the various needs that had been identified for the design and construction of up to 15000 psi hydrogen storage vessel. One of these needs was the development of Code rules for high pressure composite vessels with non-load sharing liners for stationary applications. In 2009, ASME approved new Appendix 8, for Section X Code which contains the rules for these vessels. These vessels are designated as Class III vessels with design pressure ranging from 20.7 MPa (3,000 ps)i to 103.4 MPa (15,000 psi) and maximum allowable outside liner diameter of 2.54 m (100 inches). The maximum design life of these vessels is limited to 20 years. Design, fabrication, and examination requirements have been specified, included Acoustic Emission testing at time of manufacture. The Code rules include the design qualification testing of prototype vessels. Qualification includes proof, expansion, burst, cyclic fatigue, creep, flaw, permeability, torque, penetration, and environmental testing.

Rawls, G.; Newhouse, N.; Rana, M.; Shelley, B.; Gorman, M.

2010-04-13

190

NANO-REINFORCED TITANIUM COMPOSITES AS CANDIDATE PRESSURE VESSEL MATERIALS FOR DEEP ATMOSPHERIC PROBES  

Microsoft Academic Search

Probes to Venus and the gas giants are generally composed of a heat shield protecting a spherical titanium pressure vessel. Once the high-speed entry portion of the entry is completed, the heat shield may be ejected (as was the case with Pioneer Venus) and the titanium vessel, housing the scientific instruments, is exposed to perform in-situ atmospheric measurements. The effort

M. Stackpoole; D. Srivastava; A. Fuentes; B. Cruden; J. O. Arnold

191

Pesticide Chemical Runaway Reaction Pressure Vessel Explosion (Two Killed, Eight Injured). Investigation Report.  

National Technical Information Service (NTIS)

On August 28, 2008, at about 10:35 p.m., a runaway chemical reaction occurred inside a 4,500 gallon pressure vessel known as a residue treater, causing the vessel to explode violently in the methomyl unit at the Bayer CropScience facility in Institute, We...

2011-01-01

192

HFIR Vessel Pressure\\/Temperature Limits Corresponding to the Upgrade Design  

Microsoft Academic Search

Pressure\\/temperature limits were calculated for the HFIR pressure vessel for a temperature range of 40 to 120 F. New values were necessary for the upgrade design of the reactor and were calculated using a probabilistic fracture mechanics approach that accounts for the success of periodic hydrostatic proof testing. The range of calculated pressure corresponding to the specific range of temperatures

R. D. Cheverton; J. W. Bryson

2000-01-01

193

Pressure Vessel and Internals of the International Reactor Innovative and Secure  

SciTech Connect

IRIS (International Reactor Innovative and Secure) is a modular, integral light water cooled, low-to-medium power reactor, which addresses the requirements defined by the US DOE for Generation IV reactors. Its integrated layout features a pressure vessel containing all the main primary circuit components: the internals and the biological shield, here described together with the pressure vessel, plus the steam generators, the pressurizer, and the main coolant pumps described in companion papers. For this reason the pressure vessel is a crucial component of the plant, which deserves the most demanding design effort. The wide inner annulus around the core is exploited to insert steel plates, in order to improve the inner shielding capability up to the elimination of the external biological shielding and to simplify decommissioning activities by having all the irradiated components inside the vessel. (authors)

Lombardi, C.V.; Padovani, E.; Cammi, A. [Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133 Milano (Italy); Collado, J.M. [Equipos Nucleares S.A. (Spain); Santoro, R.T.; Barnes, J.M. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States)

2002-07-01

194

Dosimetry and Fluence Calculations on French PWR (Pressurized Water Reactor) Vessels Comparisons Between Experiments and Calculations.  

National Technical Information Service (NTIS)

Fluence and damage calculations on PWR pressure vessels and irradiation test specimens are presented for two types of reactor: the Franco-Belgian (reactor CHOOZ) and the French reactors (CPY program). Comparisons with measurements are given for activation...

J. C. Nimal L. Bourdet R. Lloret A. Abevilaqua

1988-01-01

195

Fabrication Flaw Density and Distribution in Repairs to Reactor Pressure Vessel and Piping Welds.  

National Technical Information Service (NTIS)

The Pacific Northwest National Laboratory is developing a generalized fabrication flaw distribution for the population of nuclear reactor pressure vessels and for piping welds in U.S. operating reactors. The purpose of the generalized flaw distribution is...

F. A. Simonen G. J. Schuster S. R. Doctor

2008-01-01

196

98. ARAIII. ML1 reactor pressure vessel is lowered into reactor ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

98. ARA-III. ML-1 reactor pressure vessel is lowered into reactor pit by hoist. July 13, 1963. Ineel photo no. 63-4049. Photographer: Lowin. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

197

Behavior of surface flaws in reactor pressure vessels under thermal-shock loading conditions  

Microsoft Academic Search

A pressurized-water, nuclear-reactor pressure vessel can be subjected to a severe thermal shock in the event of a loss-of-coolant accident (LOCA). If at the time of the LOCA there is a crack-like defect on the inner surface of the vessel, the crack may propagate as a result of the thermal shock. This paper discusses the conditions necessary for crack propagation

R. D. Cheverton; S. E. Bolt; P. P. Holz; S. K. Iskander

1981-01-01

198

Pressure measurements of nonplanar stress waves  

SciTech Connect

A useful gage has been developed for measuring pressure of nonplanar or obliquely incident stress waves. The measurements made with these gages are not as precise as direct strain gage measurements, but are very good considering the conditions under which these gages are used. We feel a need to further develop our ability to measure nonplanar stress waves in the 0 to 10 kbar range. Carbon or ytterbium will probably be chosen for the sensing element.

Carlson, G.H.; Charest, J.A.

1981-02-27

199

Analysis of gamma ray displacement damage in Light Water Reactor pressure vessels  

SciTech Connect

In addition to fast neutrons, the copious energetic gamma rays, present in a reactor environment, induce displacement damage in the reactor pressure vessel. The contribution of gamma ray damage to embrittlement is most pronounced in reactors with large water gaps separating the core from the reactor pressure vessel. Water moderates the energies of fast neutrons much more effectively than it attenuates the high energy gamma flux, and thus enhances the high energy gamma flux, incident on the vessel relative to the fast neutron flux. In this paper, an analysis of computer transport calculations is presented which quantifies the relative contribution of gamma ray damage in various pressure vessels. The results indicate that gamma ray damage must be included for accurate predictions of radiation-induced embrittlement.

Alexander, D.E.; Rehn, L.E.

1995-05-01

200

HFIR Vessel Pressure/Temperature Limits Corresponding to the Upgrade Design  

SciTech Connect

Pressure/temperature limits were calculated for the HFIR pressure vessel for a temperature range of 40 to 120 F. New values were necessary for the upgrade design of the reactor and were calculated using a probabilistic fracture mechanics approach that accounts for the success of periodic hydrostatic proof testing. The range of calculated pressure corresponding to the specific range of temperatures is 634 to 987 psi for ''pressure safety limit'' and 564 to 895 psi for the ''limiting conditions for operation.''

Cheverton, R.D.; Bryson, J.W.

2000-03-01

201

Oxidative stress in hypobaric hypoxia and influence on vessel-tone modifying mediators.  

PubMed

Abstract Pichler Hefti, Jacqueline, Denise Sonntag, Urs Hefti, Lorenz Risch, Otto D. Schoch, Alexander J. Turk, Thomas Hess, Konrad E Bloch, Marco Maggiorini, Tobias M. Merz, Klaus M. Weinberger, and Andreas R. Huber. Oxidative stress in hypobaric hypoxia and influence on vessel-tone modifying mediators. High Alt Med Biol. 14:273-279, 2013.-Increased pulmonary artery pressure is a well-known phenomenon of hypoxia and is seen in patients with chronic pulmonary diseases, and also in mountaineers on high altitude expedition. Different mediators are known to regulate pulmonary artery vessel tone. However, exact mechanisms are not fully understood and a multimodal process consisting of a whole panel of mediators is supposed to cause pulmonary artery vasoconstriction. We hypothesized that increased hypoxemia is associated with an increase in vasoconstrictive mediators and decrease of vasodilatators leading to a vasoconstrictive net effect. Furthermore, we suggested oxidative stress being partly involved in changement of these parameters. Oxygen saturation (Sao2) and clinical parameters were assessed in 34 volunteers before and during a Swiss research expedition to Mount Muztagh Ata (7549?m) in Western China. Blood samples were taken at four different sites up to an altitude of 6865?m. A mass spectrometry-based targeted metabolomic platform was used to detect multiple parameters, and revealed functional impairment of enzymes that require oxidation-sensitive cofactors. Specifically, the tetrahydrobiopterin (BH4)-dependent enzyme nitric oxide synthase (NOS) showed significantly lower activities (citrulline-to-arginine ratio decreased from baseline median 0.21 to 0.14 at 6265?m), indicating lower NO availability resulting in less vasodilatative activity. Correspondingly, an increase in systemic oxidative stress was found with a significant increase of the percentage of methionine sulfoxide from a median 6% under normoxic condition to a median level of 30% (p<0.001) in camp 1 at 5533?m. Furthermore, significant increase in vasoconstrictive mediators (e.g., tryptophan, serotonin, and peroxidation-sensitive lipids) were found. During ascent up to 6865?m, significant altitude-dependent changes in multiple vessel-tone modifying mediators with excess in vasoconstrictive metabolites could be demonstrated. These changes, as well as highly significant increase in systemic oxidative stress, may be predictive for increase in acute mountain sickness score and changes in Sao2. PMID:24067187

Pichler Hefti, Jacqueline; Sonntag, Denise; Hefti, Urs; Risch, Lorenz; Schoch, Otto D; Turk, Alexander J; Hess, Thomas; Bloch, Konrad E; Maggiorini, Marco; Merz, Tobias M; Weinberger, Klaus M; Huber, Andreas R

2013-09-01

202

Investigation of hydrogen-assisted cracking in low strength pressure vessel steels  

NASA Astrophysics Data System (ADS)

Hydrogen assisted cracking (HAC) has been investigated in high strength 4140 and low strength Z17D pressure vessel steels, charged at --50 mA/cm 2 in 1N H2SO4 + 25 mg/l As2O 3 and tested under three-point bend decreasing load. The HAC growth rate for Z17D steel (1.4 x 10--7 cm/s) was found to be approximately two orders of magnitude slower than that of 4140 steel (3.3 x 10--5 cm/s), while the threshold stress intensity factor for Z17D steel (˜37 MPa?m) was significantly higher than that of 4140 steel ˜7 MPa?m). This thesis will show that a single analytical model, based on the hypothesis that hydrogen both reduces crack resistance (R) and increases crack driving force (G), can explain HAC in 4140 and Z17D steels. The model predicts the hydrogen concentration required to initiate HAC as a function of the stress intensity factor and yield strength of the steel. Hydrogen-induced reduction of R was found to dominate HAC in 4140 steel, while hydrogen-induced reduction of R was combined with an increase in G for HAC cracking of Z17D steel.

Tantaseraneewat, Samerjit

2000-10-01

203

The influence of long-time stress relief treatments on the dynamic fracture toughness properties of ASME SA508 C1 2a and ASME SA533 Gr B C1 2 pressure vessel steels  

Microsoft Academic Search

Dynamic fracture toughness tests were performed on SA508 Cl 2a and SA533 Gr B Cl 2 parent base materials which had been subjected\\u000a to one of three longtime post weld type stress relief heat treatments: 48 hours at 1000 °F (538 °C), 24 hours at 1125 °F (607\\u000a °C), and 48 hours at 1125 °F (607 °C). Linear elastic Kld

W. A. Logsdon

1982-01-01

204

Creep failure of a reactor pressure vessel lower head under severe accident conditions  

SciTech Connect

A severe accident in a nuclear power plant could result in the relocation of large quantities of molten core material onto the lower head of he reactor pressure vessel (RPV). In the absence of inherent cooling mechanisms, failure of the RPV ultimately becomes possible under the combined effects of system pressure and the thermal heat-up of the lower head. Sandia National Laboratories has performed seven experiments at 1:5th scale simulating creep failure of a RPV lower head. This paper describes a modeling program that complements the experimental program. Analyses have been performed using the general-purpose finite-element code ABAQUS-5.6. In order to make ABAQUS solve the specific problem at hand, a material constitutive model that utilizes temperature dependent properties has been developed and attached to ABAQUS-executable through its UMAT utility. Analyses of the LHF-1 experiment predict instability-type failure. Predicted strains are delayed relative to the observed strain histories. Parametric variations on either the yield stress, creep rate, or both (within the range of material property data) can bring predictions into agreement with experiment. The analysis indicates that it is necessary to conduct material property tests on the actual material used in the experimental program. The constitutive model employed in the present analyses is the subject of a separate publication.

Pilch, M.M.; Ludwigsen, J.S.; Chu, T.Y. [Sandia National Labs., Albuquerque, NM (United States); Rashid, Y.R. [Anatech, San Diego, CA (United States)

1998-08-01

205

A study of fatigue crack propagation in prior hydrogen attacked pressure vessel steels  

NASA Astrophysics Data System (ADS)

A study has been made of the effects of prior hydrogen attack damage on fatigue crack propagation behavior in commercial pressure vessel steels. Quenched and tempered Mn-Mo-Ni steel (ASTM A533B Class 2) and normalized and tempered 2.25Cr-1Mo steel (ASTM A387 Class 2 Grade 22) were exposed to gaseous hydrogen atmospheres for up to 1480 hours at hydrogen pressures of 12.4 to 17.2 MPa and temperatures of 550° to 600°C and tested in fatigue. Mild degrees of hydrogen damage, characterized by limited methane bubble formation with no appreciable decarburization, were found to increase growth rates slightly at near-threshold stress intensities. Severe degrees of hydrogen damage, characterized by extensive intergranular bubble formation and decarburization with associated large reductions in strength and toughness, were found to have no further influence on near-threshold growth rates. The minor influence of prior hydrogen damage on fatigue crack extension, even for cases of severe attack, is attributed to result from two mutually competitive mechanisms, namely, the creation of methane-filled voids on prior austenite grain boundaries, which increases growth rates, and the enhancement in crack closure from decarburization-induced softening and rough cavitated intergranular fracture surfaces, which decreases growth rates.

Pendse, R. D.; Ritchie, R. O.

1985-08-01

206

Lessons learned from the plant-specific pressurized thermal shock integrity analysis on an embrittled reactor pressure vessel  

Microsoft Academic Search

The reference temperature of pressurized thermal shock (PTS) of the reactor pressure vessel (RPV) for the oldest pressurized water reactor in Korea had been predicted to exceed screening criteria of 10CFR50.61. To cope with this issue, a plant-specific PTS analysis had been performed following the methodology and procedures suggested in Reg. Guide 1.154. In this paper, the details of the

Ill-Seok Jeong; Changhuei Jang; Jun-Hyun Park; Sung-Yull Hong; Tae-Eun Jin; Hag-Gi Yuem; Sung-Gyu Jeong

2001-01-01

207

Teaching Evolutionary Biology: Pressures, Stress, and Coping  

ERIC Educational Resources Information Center

|Understanding what teachers need to be more comfortable and confident in their profession is crucial to the future of effective teachers and scientific literacy in public schools. This study focuses on the experiences of Arizona biology teachers in teaching evolution, using a clinical model of stress to identify sources of pressure, the resulting…

Griffith, Joyce A.; Brem, Sarah K.

2004-01-01

208

Probabilistic deformation and strength prediction for a filament wound pressure vessel  

Microsoft Academic Search

In this study; probabilistic analysis and experimental tests are conducted to predict the probabilistic deformation and strength of composite pressure vessels subjected to inner pressure loading. A computer code was utilized for the progressive failure analysis and probabilistic strength analysis with the Edgeworth expansion method and the Monte-Carlo method. The effects of design random variables on the structural behavior of

Tae-Kyung Hwang; Chang-Sun Hong; Chun-Gon Kim

2003-01-01

209

HFIR Vessel Maximum Permissible Pressures for Operating Period 26 to 50 EFPY (100 MW)  

SciTech Connect

Extending the life of the HFIR pressure vessel from 26 to 50 EFPY (100 MW) requires an updated calculation of the maximum permissible pressure for a range in vessel operating temperatures (40-120 F). The maximum permissible pressure is calculated using the equal-potential method, which takes advantage of knowledge gained from periodic hydrostatic proof tests and uses the test conditions (pressure, temperature, and frequency) as input. The maximum permissible pressure decreases with increasing time between hydro tests but is increased each time a test is conducted. The minimum values that occur just prior to a test either increase or decrease with time, depending on the vessel temperature. The minimum value of these minimums is presently specified as the maximum permissible pressure. For three vessel temperatures of particular interest (80, 88, and 110 F) and a nominal time of 3.0 EFPY(100 MVV)between hydro tests, these pressures are 677, 753, and 850 psi. For the lowest temperature of interest (40 F), the maximum permissible pressure is 295 psi.

Cheverton, R.D.; Inger, J.R.

1999-01-01

210

Thrombospondin1 and CD47 regulate blood pressure and cardiac responses to vasoactive stress  

Microsoft Academic Search

Nitric oxide (NO) locally regulates vascular resistance and blood pressure by modulating blood vessel tone. Thrombospondin-1 signaling via its receptor CD47 locally limits the ability of NO to relax vascular smooth muscle cells and increase regional blood flow in ischemic tissues. To determine whether thrombospondin-1 plays a broader role in central cardiovascular physiology, we examined vasoactive stress responses in mice

Jeff S. Isenberg; Yan Qin; Justin B. Maxhimer; John M. Sipes; Daryl Despres; Jurgen Schnermann; William A. Frazier; David D. Roberts

2009-01-01

211

Design of a standalone-type beryllium vessel for high-pressure protein crystallography.  

PubMed

A standalone-type beryllium (Be) high-pressure crystallography vessel has been developed. Using a coupler-joint unit and a pressure valve, we could keep the pressure in the vessel constant at 100+/-1 MPa for more than 24 h without connecting to a pressure-generating apparatus. Diffraction spots of a glucose isomerase (GI) crystal under 100 MPa were collected using the vessel and a rotating copper-anode in-house x-ray generator (0.8 kW). We successfully collected a 2.0 A resolution data set of a 0.5 mm size GI crystal in an aqueous solution at 100 MPa. PMID:20815618

Suzuki, Yoshihisa; Tsukamoto, Masayuki; Sakuraba, Haruhiko; Matsumoto, Masamitsu; Nagasawa, Makoto; Tamura, Katsuhiro

2010-08-01

212

Development of composite pressure vessels with nonmetallic liners  

NASA Astrophysics Data System (ADS)

Brunswick composites has developed metallic liners and composite cylinders for use in military and civilian aircraft, missiles, inflation systems and space applications. At present an all-composite pressurant tank is being developed for use in the natural gas vehicle (NGV). This tank uses a plastic liner of high density polyethylene (HDPE) as a leak-tight permeation barrier. Tank characteristics and testing are described. HDPE reduces cost, meets all space and missile pressurant tank requirements, and is readily availble. Test results indicate that an all-composite pressurant tank with an HDPE liner provides a tough, high cycle life, lightweight, environmentally stable pressurant tank with very low permeability. HDPE offers a viable, low cost alternative to conventional metal liners as well as many design advantages.

Murray, Con F.; Newhouse, Norman L.; Schimenti, John D.; Tiller, Dale B.

1992-07-01

213

Impact of radiation embrittlement on integrity of pressure vessel supports for two PWR (pressurized-water-reactor) plants  

SciTech Connect

Recent pressure-vessel surveillance data from the High Flux Isotope Reactor (HFIR) indicate an embrittlement fluence-rate effect that is applicable to the evaluation of the integrity of light-water reactor (LWR) pressure vessel supports. A preliminary evaluation using the HFIR data indicated increases in the nil ductility transition temperature at 32 effective full-power years (EFPY) of 100 to 130/degree/C for pressurized-water-reactor (PWR) vessel supports located in the cavity at midheight of the core. This result indicated a potential problem with regard to life expectancy. However, an accurate assessment required a detailed, specific-plant, fracture-mechanics analysis. After a survey and cursory evaluation of all LWR plants, two PWR plants that appeared to have a potential problem were selected. Results of the analyses indicate minimum critical flaw sizes small enough to be of concern before 32 EFPY. 24 refs., 16 figs., 7 tabs.

Cheverton, R.D.; Pennell, W.E.; Robinson, G.C.; Nanstad, R.K.

1988-01-01

214

OPTIMAL DESIGN OF TORISPHERICAL PRESSURE VESSEL END CLOSURES  

Microsoft Academic Search

The problem of minimizing the maximum shearing stresses occurring in torispherical heads of two and three radii is presented. A system model is formulated from the design variables describing the head shapes and this model is optimized by using a penalty function procedure combined with a variable metric unconstrained minimization technique. Various examples of the algorithm are illustrated and the

J. MIDDLETON

1979-01-01

215

Feasibility for development of a nuclear reactor pressure vessel flaw distribution: Sensitivity analyses and NDE (nondestructive evaluation) capability  

SciTech Connect

Pressurized water reactor pressure vessels operate under US Nuclear Regulatory Commission (NRC) rules and regulatory guides that are intended to maintain a low probability of vessel failure. The NRC has also addressed neutron embrittlement of pressurized water reactor pressure vessels by imposing regulations on plant operation. Plants failing to meet the operating criteria specified by these rules and regulations are required, among other things, to analytically demonstrate fitness for service in order to continue safe operation. The initial flaw size or distribution of initial vessel flaws is a key input to the required vessel integrity analyses. A fracture mechanics sensitivity study was performed to quantify the effect of the assumed flaw distribution on the predicted vessel performance under a specified pressurized thermal shock transient and to determine the critical crack size. Results of the analysis indicate that vessel performance in terms of the estimated probability of failure is very sensitive to the assumed flaw distribution. 20 refs., 3 figs., 2 tabs.

Rosinski, S.T. (Sandia National Labs., Albuquerque, NM (USA)); Kennedy, E.L.; Foulds, J.R. (Failure Analysis Associates, Inc., Menlo Park, CA (USA))

1990-01-01

216

Role of crack arrest in the evaluation of PWR pressure vessel integrity during PTS transients  

Microsoft Academic Search

The PWR pressurized thermal-shock (PTS) issue, which is concerned with the integrity of the reactor pressure vessel during postulated overcooling transients, is under intensive investigation by the USNRC. The USNRC-sponsored Integrated Pressurized Thermal-Shock (IPTS) and Heavy-Section Steel Technology (HSST) Programs are dedicated to a better understanding and a timely resolution of the problem. The HSST program is investigating flaw behavior

R. D. Cheverton; D. G. Ball

1984-01-01

217

Pressure measurements of nonplanar stress waves  

SciTech Connect

Measuring the pressure of non-planar stress waves using thin piezo-resistive gages requires correcting for induced strain parallel to the sensing elements. A technique has been developed that permits such measurements, making use of a dual element gage. One element, Manganin, is sensitive to stress both parallel and perpendicular to the sensing element; the other element, Constantan, is primarily sensitive to stress parallel to the sensing element. The change in resistance in the Constantan element is thereby used to correct for the strain effect parallel to the Manganin element axis. Individual and combined Manganin and Constantan elements were subjected to controlled gas gun impact tests in the pressure and strain ranges of 0 to 50 kbar and 0 to 7%, respectively. From planar wave tests, the piezoresistivity of Constantan was found to be positive but negligible in comparison with Manganin. From combined stress and strain environments, the compression and tension strain factors of Constantan were found to be constant and equal to 2.06. The strain factors of Manganin were found to increase from 1.2 to 2.0 asymptotically in the range of 0 to 3% strain. It was experimentally demonstrated that, because of the closeness of their strain factors, the Manganin-Constantan dual element gage could be used in the differential recording mode to yield pressure directly. In this mode the gage is a strain compensating gage. Analytical techniques have also been developed for more accurate strain compensation.

Carlson, G.H.; Charest, J.A.

1981-01-01

218

Failure analysis of ETAC (Enrichment Technology Applications Center) pressure vessel  

SciTech Connect

This report presents the results of an investigation into the failure of a graphite-epoxy composite cylinder. It investigates the quality of the as-fabricated cylinder and provides a verification of compressive material property input used in its design. The design is reevaluated in terms of the adjusted composition and material property input for its suitability for 18,000-psi pressure applications. A comparison between the composition and layup of a cylinder manufactured by Hitco is also provided, as well as the results of a pressurization test of an identical ETAC cylinder tested by the Naval Ocean Systems Center.

Frame, B.J.

1987-06-01

219

J-integral patch for finite element analysis of dynamic fracture due to impact of pressure vessels  

NASA Astrophysics Data System (ADS)

Prediction of whether a pressurized cylinder will fail catastrophically when impacted by a projectile has important applications ranging from perforation of an airplane's skin by a failed turbine blade to meteorite impact of a space station habitation module. This report summarizes the accomplishment of one task for a project whose aim is to simulate numerically the outcome of a high velocity impact of pressure vessels. A finite element patch covering the vicinity of a growing crack has been constructed to estimate the J-integral (crack driving force) during the impact. Explicit expressions for the J-integral through the nodal values of displacement, strain, and stress have been written. The patch is to be used repeatedly to estimate the amount of crack growth during the time of the impact. The resulting crack size is to be compared to an estimated critical crack size for the pressurized cylinder.

Kunin, Boris I.

1993-11-01

220

Use of Master Curve technology for assessing shallow flaws in a reactor pressure vessel material  

SciTech Connect

In the NESC-IV project an experimental/analytical program was performed to develop validated analysis methods for transferring fracture toughness data to shallow flaws in reactor pressure vessels subject to biaxial loading in the lower-transition temperature region. Within this scope an extensive range of fracture tests was performed on material removed from a production-quality reactor pressure vessel. The Master Curve analysis of this data is reported and its application to the assessment of the project feature tests on large beam test pieces.

Bass, Bennett Richard [ORNL; Taylor, Nigel [EC JRC-IE, Petten, The Netherlands

2006-01-01

221

PALS combined with Charpy-V tests at WWER reactor pressure vessel steels  

NASA Astrophysics Data System (ADS)

This paper presents results from our long-term studies of irradiated, commercially used WWER reactor pressure vessel steels. Results from Charpy-V tests and positron annihilation spectroscopy techniques are compared and discussed in details, having in mind actual state of art and other microstructural studies in this area. The optimal region for annealing of irradiation induced defects was analyzed. It was shown that WWER steel with low impurity contents has good radiation stability and operation these reactor pressure vessels could be extended beyond a design lifetime.

Sluge?, V.; Kryukov, A.; Petriska, M.; Veterníková, J.; Sojak, S.; Sabelová, V.; Hinca, R.

2013-06-01

222

Role of probabilistic analysis in integrity assessments of reactor pressure vessels exposed to pressurized thermal-shock conditions  

Microsoft Academic Search

In recent years, probabilistic analyses have been playing an increasing role in safety assessments for nuclear power plants (NPPs) in the USA. An important example is the treatment of integrity analyses for the primary reactor pressure vessel (RPV) when it is exposed to pressurized thermal-shock (PTS) events. The U.S. Nuclear Regulatory Commission’s (NRC) approach to ensuring PTS integrity over the

Claud E. Pugh; B. Richard Bass; Terry L. Dickson

2007-01-01

223

Rupture Properties of Blood Vessel Walls Measured by Pressure-Imposed Test  

NASA Astrophysics Data System (ADS)

It is expected to be clinically useful to know the mechanical properties of human aortic aneurysms in assessing the potential for aneurysm rupture. For this purpose, a newly designed experimental setup was fabricated to measure the rupture properties of blood vessel walls. A square specimen of porcine thoracic aortas is inflated by air pressure at a rate of 10mmHg/s (?1.3MPa/s) until rupture occurs. Mean breaking stress was 1.8±0.4 MPa (mean±SD) for the specimens proximal to the heart and 2.3±0.8MPa for the distal specimens, which are not significantly different to those values obtained longitudinally from conventional tensile tests. Moreover, the local breaking stretch ratio in the longitudinal direction was significantly higher at the ruptured site (2.7±0.5) than at the unruptured site (2.2±0.4). This testing system for studying the rupture properties of aortic walls is expected to be applicable to aortic aneurysms. Experimental verification of the present technique for the homogeneous, isotropic material is also presented.

Ohashi, Toshiro; Sugita, Syukei; Matsumoto, Takeo; Kumagai, Kiichiro; Akimoto, Hiroji; Tabayashi, Koichi; Sato, Masaaki

224

Temperature Field and Thermal Stress Analysis of the HT-7U Vacuum Vessel  

NASA Astrophysics Data System (ADS)

The HT-7U vacuum vessel is an all-metal-welded double-wall interconnected with toroidal and poloidal stiffening ribs. The channels formed between the ribs and walls are filled with boride water as a nuclear shielding. On the vessel surface facing the plasma are installed cable-based Ohmic heaters. Prior to plasma operation the vessel is to be baked out and discharge cleaned at about 250°C. During baking out the non-uniformity of temperature distribution on the vacuum vessel will bring about serious thermal stress that can damage the vessel. In order to determine and optimize the design of the HT-7U vacuum vessel, a three-dimensional finite element model was performed to analyse its temperature field and thermal stress. The maximal thermal stress appeared on the round of lower vertical port and maximal deformation located just on the region between the upper vertical port and the horizontal port. The results show that the reinforced structure has a good capability of withstanding the thermal loads.

Song, Yun-tao; Yao, Da-mao; Wu, Song-tao; Weng, Pei-de

2000-10-01

225

Fast neutron fluence of yonggwang nuclear unit 1 reactor pressure vessel  

SciTech Connect

The Code of Federal Regulations, Title 10, Part 50, Appendix H, requires that the neutron dosimetry be present to monitor the reactor vessel throughout plant life. The Ex-Vessel Neutron Dosimetry System has been installed for Yonggwang Nuclear Unit 1 after complete withdrawal of all six in-vessel surveillance capsules. This system has been installed in the reactor cavity annulus in order to measure the fast neutron spectrum coming out through the reactor pressure vessel. Cycle specific neutron transport calculations were performed to obtain the energy dependent neutron flux throughout the reactor geometry including dosimetry positions. Comparisons between calculations and measurements were performed for the reaction rates of each dosimetry sensors and results show good agreements. (authors)

Yoo, C.; Km, B.; Chang, K.; Leeand, S. [Korea Atomic Energy Research Inst., 150 Dukjin-dong, Yuseung-gu, Daejeon 305-353 (Korea, Republic of); Park, J. [Chungnam National Univ., 220 Gung-dong, Yuseung-gu, Daejeon 305-764 (Korea, Republic of)

2006-07-01

226

Reactor Pressure Vessel Temperature Analysis for Prismatic and Pebble-Bed VHTR Designs  

SciTech Connect

Analyses were performed to determine maximum temperatures in the reactor pressure vessel for two potential Very-High Temperature Reactor (VHTR) designs during normal operation and during a depressurized conduction cooldown accident. The purpose of the analyses was to aid in the determination of appropriate reactor vessel materials for the VHTR. The designs evaluated utilized both prismatic and pebble-bed cores that generated 600 MW of thermal power. Calculations were performed for fluid outlet temperatures of 900 and 950 °C, corresponding to the expected range for the VHTR. The analyses were performed using the RELAP5-3D and PEBBED-THERMIX computer codes. Results of the calculations were compared with preliminary temperature limits derived from the ASME pressure vessel code.

H. D. Gougar; C. B. Davis

2006-04-01

227

EQUATIONS FOR GAS RELEASING PROCESS FROM PRESSURIZED VESSELS IN ODH EVALUATION.  

SciTech Connect

IN THE EVALUATION OF ODH, THE CALCULATION OF THE SPILL RATE FROM THE PRESSURIZED VESSEL IS THE CENTRAL TASK. THE ACCURACY OF THE ENGINEERING ESTIMATION BECOMES ONE OF THE SAFETY DESIGN ISSUES. THIS PAPER SUMMARIZES THE EQUATIONS FOR THE OXYGEN CONCENTRATION CALCULATION IN DIFFERENT CASES, AND DISCUSSES THE EQUATIONS FOR THE GAS RELEASE PROCESS CALCULATION BOTH FOR THE HIGH-PRESSURE GAS TANK AND THE LOW-TEMPERATURE LIQUID CONTAINER.

JIA,L.X.; WANG,L.

2001-07-16

228

A study of fatigue crack propagation in prior hydrogen attacked pressure vessel steels  

Microsoft Academic Search

A study has been made of the effects of prior hydrogen attack damage on fatigue crack propagation behavior in commercial pressure vessel steels. Quenched and tempered Mn-Mo-Ni steel (ASTM A533B Class 2) and normalized and tempered 2.25Cr-1Mo steel (ASTM A387 Class 2 Grade 22) were exposed to gaseous hydrogen atmospheres for up to 1480 hours at hydrogen pressures of 12.4

R. D. Pendse; R. O. Ritchie

1985-01-01

229

A study of fatigue crack propagation in prior hydrogen attacked pressure vessel steels  

Microsoft Academic Search

A study has been made of the effects of prior hydrogen attack damage on fatigue crack propagation behavior in commercial pressure\\u000a vessel steels. Quenched and tempered Mn-Mo-Ni steel (ASTM A533B Class 2) and normalized and tempered 2.25Cr-1Mo steel (ASTM\\u000a A387 Class 2 Grade 22) were exposed to gaseous hydrogen atmospheres for up to 1480 hours at hydrogen pressures of 12.4

R. D. Pendse; R. O. Ritchie

1985-01-01

230

Creep failure of a reactor pressure vessel lower head under severe accident conditions.  

National Technical Information Service (NTIS)

A severe accident in a nuclear power plant could result in the relocation of large quantities of molten core material onto the lower head of he reactor pressure vessel (RPV). In the absence of inherent cooling mechanisms, failure of the RPV ultimately bec...

M. M. Pilch J. S. Ludwigsen T. Y. Chu Y. R. Rashid

1998-01-01

231

Effect of welding processes on toe cracking behaviour of pressure vessel grade steel  

Microsoft Academic Search

The effect of welding processes on fatigue crack growth behaviour of load carrying cruciform joints has been analysed. Cruciform joints were fabricated from pressure vessel grade (ASTM 517 ‘F’ grade) steel using shielded metal arc welding (SMAW) and flux cored arc welding (FCAW) processes. Fatigue crack growth experiments were carried out in a mechanical resonance vertical pulsator (SCHENCK 200 kN

V. Balasubramanian; B. Guha

2004-01-01

232

Corrosion fatigue in pressure vessel steels: Results of ENEL-CISE programs.  

National Technical Information Service (NTIS)

This paper briefly describes the results of a large ENEL (Italian Electricity Board) program on corrosion fatigue in pressure vessel steel in nuclear grade water. The experimental data show that, for this material, the use of the superposition model can b...

G. Gabetta S. Ragazzoni

1989-01-01

233

Test Results Using a Bell Jar to Measure Containment Vessel Pressurization  

SciTech Connect

A bell jar is used to determine containment vessel pressurization due to outgassing of plutonium materials. Fifteen food cans containing plutonium bearing materials, including plutonium packaged in direct contact with plastic and plutonium contaminated enriched oxide have been tested to date.

Hensel, S.J.

2002-05-10

234

Fatigue Fracture Features of Pressure Vessel Steel in Simulated Light Water Reactor Environment  

Microsoft Academic Search

To evaluate fatigue crack growth of reactor pressure vessel steel at reactor operating conditions, tests were performed in air saturated hot water. The main test parameter was a loading frequency. Crack growth rate was increased with decreasing frequency up to a critical value. It was assumed through fractographic study and surface analysis that the enhancement of crack growth rate was

Sang Gyu LEE; In Sup KIM

2001-01-01

235

Exploratory Study of Irradiation, Annealing, and Reirradiation Effects on American and Russian Reactor Pressure Vessel Steels  

Microsoft Academic Search

One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPVS) is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. even though a postirradiation anneal may be deemed successful, a critical aspect of continued RPV operation is the rate of embrittlement upon reirradiation. There are insufficient data available

Chernobaeva; Kryukov; Nikolaev

1997-01-01

236

Irradiation, Annealing, and Reirradiation Effects on American and Russian Reactor Pressure Vessel Steels  

Microsoft Academic Search

One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPVs) is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. Even though a postirradiation anneal may be deemed successful, a critical aspect of continued RPV operation is the rate of embrittlement upon reirradiation. There are insufficient data available

A. A. Chernobaeva; Y. N. Korolev; R. K. Nanstad; Y. A. Nikolaev; M. A. Sokolov

1998-01-01

237

Solving pressure vessel design problems by an effective global harmony search algorithm  

Microsoft Academic Search

We use an effective global harmony search algorithm (EGHS) to solve two kinds of pressure vessel design problems. In general, the two problems are formulated as mixed-integer non-linear programming problems with several constraints. The EGHS combines harmony search algorithm (HS) with concepts from the swarm intelligence of particle swarm optimization algorithm (PSO) to solve the two optimization problems. The EGHS

Liqun Gao; Dexuan Zou; Yanfeng Ge; Wenjing Jin

2010-01-01

238

FATIGUE ANALYSIS METHODS: THEIR PERFORMANCE EVALUATION FOR A CLASS OF PRESSURE VESSELS WITH WELDED JOINTS  

Microsoft Academic Search

This paper provides a basis for evaluating the performance of a fatigue analysis method for a selected class of welded pressure vessels. After the allowable number of cycles that the method permits for a member of the class is calculated, the question is addressed whether that number of cycles can be regarded as conservative or unconservative. To answer that question,

Arturs Kalnins

2009-01-01

239

Detailed evaluation of coolant injection into the reactor vessel with RCS depressurization for high pressure sequences  

Microsoft Academic Search

A coolant injection into the reactor vessel with depressurization of the reactor coolant system (RCS) has been evaluated as part of the evaluation for a strategy of the severe accident management guidance (SAMG). Two high pressure sequences of a small break loss of coolant accident (LOCA) without safety injection (SI) and a total loss of feedwater (LOFW) accident in Optimized

Rae-Joon Park; Sang-Baik Kim; Seong-Wan Hong; Hee-Dong Kim

2009-01-01

240

An investigation of temperature measurement methods in nuclear power plant reactor pressure vessel annealing  

Microsoft Academic Search

The objective of this project was to provide an assessment of several methods by which the temperature of a commercial nuclear power plant reactor pressure vessel (RPV) could be measured during an annealing process. This project was a coordinated effort between DOE`s Office of Nuclear Energy, Science and Technology; DOE`s Light Water Reactor Technology Center at Sandia National Laboratories; and

R. U. Acton; W. Gill; D. J. Sais; D. H. Schulze; J. T. Nakos

1996-01-01

241

Walking and Climbing Service Robots for Safety Inspection of Nuclear Reactor Pressure Vessels  

Microsoft Academic Search

Nuclear reactor pressure vessels are often required regular inspection and maintenance in order to ensure the safety of the reactors. Failing to carry out proper maintenance could cause severe casualty. The usual way of carrying out inspection in these hazardous environments is using long reach fixed base manipulators. However, these manipulators suffer from low payload capacity and relatively large end

B. L. Luka; A. A. Collie; S. Chen

242

Probabilistic fracture mechanics analyses of nuclear pressure vessels under PTS events  

Microsoft Academic Search

This paper describes some recent research activities on probabilistic fracture mechanics (PFM) for nuclear reactor pressure vessels (RPVs) performed by the RC111 research committee of the Japan Society of Mechanical Engineers (JSME) under a subcontract of the Japan Atomic Energy Research Institute (JAERI). To establish standard procedures for evaluating failure probabilities of nuclear RPVs, we have performed PFM analyses for

G Yagawa; S Yoshimura; N Soneda; M Hirano

1997-01-01

243

Fundamental study of failure mechanisms of pressure vessels under thermo-mechanical cycling in multiphase environments  

Microsoft Academic Search

Cracking and bulging in welded and internally lined pressure vessels that work in thermal-mechanical cycling services have been well known problems in the petrochemical, power and nuclear industries. Published literature and industry surveys show that similar problems have been occurring during the last 50 years. Understanding the causes of cracking and bulging would lead to improvements in the reliability of

Jorge Antonio Penso Mula

2001-01-01

244

On the character of nanoscale features in reactor pressure vessel steels under neutron irradiation  

Microsoft Academic Search

Nanostructural features that form in reactor pressure vessel steels under neutron irradiation at around 290°C are responsible for significant hardening and embrittlement. It is well established that the nanostructural features can be separated into well formed precipitates and matrix features comprised of point defect clusters complexed with solutes, which may also include regions of solute enrichment that are not well

Brian David Wirth

1998-01-01

245

Prediction of Fracture in the Transition Regime : Application to an A533B Pressure Vessel Steel  

Microsoft Academic Search

In order to model the fracture behaviour of pressure vessel steels in the transition regime, a new model has been developped in 1991 at EDF R&D Division in the framework of local approach to fracture. This approach couples the damage mechanics model developped by Rousselier which is accounting for ductile propagation of a crack, and the Beremin's model based on

C. Eripret; D. P. G. Lidbury; A. Sherry; I. Howard

1996-01-01

246

Proceedings of the 1985 pressure vessels and piping conference. Volume PVP98-6. Structural dynamics  

Microsoft Academic Search

Structural dynamics is important in the design and assessment of pressure vessels and piping components. Extensive studies on the subject are being continued to enhance understanding of response characteristics, develop new\\/improved analytical, numerical and experimental techniques, and provide more reliable design guidelines. This volume contains thirty-seven papers covering a wide variety of topics. The structural components considered vary from fueling

1985-01-01

247

Welded Joint Analysis for Pressure Vessels with Medium and Large Diameters  

Microsoft Academic Search

Welded seal joints are recommended for applications where leak proof conditions are necessary and also when the disassembly of the closure parts is not required. Normally, for pressure vessels of medium and large diameters, the relative movements between parts of the joint is considerable due to the different movements of the individual parts or different thermal expansion coefficients. The use

E. Gómez; Equipos Nucleares

248

Graphite/Epoxy Heat Sink/Mounting for Common Pressure Vessel.  

National Technical Information Service (NTIS)

The graphite-epoxy heat sink and mounting structure is comprised of a mounting structure constructed of a graphite-epoxy material that is mounted around a heat generating pressure vessel located inside a spacecraft. The mounting structure is a graphite-ep...

W. R. Braun J. C. Garner S. M. Turner N. L. Hyman

1995-01-01

249

PWR 900 MWe pressure vessel surveillance - analysis of neutron field characteristics and damage function experimental determination.  

National Technical Information Service (NTIS)

This paper presents an overview of the studies performed by CEA and EDF in the scope of the pressure vessel surveillance of the nuclear installations in France. The power plants are equipped with specimens for monitoring the effects of the irradiation to ...

J. C. Nimal L. Bourdet S. H. Zheng I. Kodeli R. Lloret

1994-01-01

250

Irradiation surveillant test of High Flux Engineering Test Reactor (HFETR) pressure vessel.  

National Technical Information Service (NTIS)

The result of irradiation surveillant test of HFETR pressure vessel is presented. It shows that after 3.3 x 10(sup 20) n/cm(sup 2) irradiation the irradiation brittleness effect in welding seam (ws) is smaller than in heat-affected zone (HAZ), and the irr...

W. Gao Y. Cui

1991-01-01

251

Numerical modeling of the behaviour of high pressure vessel under hypervelocity impact  

Microsoft Academic Search

The increase of the number of space debris, particularly in LEO, has become a menace for space missions, and Space Agencies such as CNES (French Space Agency) are worried about this phenomenon. Because high pressure vessels are critical components onboard satellites, it is important to know their behaviour under hypervelocity impact induced by space debris. The aim of the study

C. Maveyraud; J. P. Vila; D. Sornette; C. Le Floc'h; J. M. Dupillier; R. Salomé

2001-01-01

252

Dynamic fracture toughness of irradiated A533 Grade B Class 1 pressure vessel steel  

Microsoft Academic Search

The effect of neutron radiation on the fracture characteristics of an A533 Grade B Class 1 pressure vessel steel was investigated using standard and instrumented precracked Charpy impact tests. Use of the instrumented impact test with precracked specimens has allowed fracture toughness values to be determined from the Charpy test. Neutron exposure resulted in minute decreases in the upper-shelf Charpy

K. L. Murty; W. H. Bamford; R. P. Shogun

1984-01-01

253

2 1\\/4Cr1Mo steels for coal conversion pressure vessels  

Microsoft Academic Search

Pressure vessels for coal conversion processes are likely to be made of a 2 1\\/4 Cr-1 Mo steel, covered by ASTM specification A387, class 2, grade 22. Under the projected operating conditions, degradation of the mechanical properties of the steel by temper embrittlement and hydrogen embrittlement is a major concern. The significance of these degradation mechanisms is reviewed here in

R. Viswanathan; R. I. Jaffee

1982-01-01

254

2 1\\/4 Cr1 Mo steels for coal-conversion pressure vessels. [Tempering; hydrogen  

Microsoft Academic Search

Pressure vessels for coal conversion processes are likely to be made of a 2 1\\/4 Cr-1 Mo steel, covered by ASTM specification A387, class 2, grade 22. Under the projected operating conditions, degradation of the mechanical properties of the steel by temper embrittlement, hydrogen embrittlement and hydrogen attack is a major concern. The significance of these degradation mechanisms is reviewed

R. Viswanathan; R. I. Jaffee

1981-01-01

255

Optimization of Composite Material System and Lay-up to Achieve Minimum Weight Pressure Vessel  

NASA Astrophysics Data System (ADS)

The use of composite pressure vessels particularly in the aerospace industry is escalating rapidly because of their superiority in directional strength and colossal weight advantage. The present work elucidates the procedure to optimize the lay-up for composite pressure vessel using finite element analysis and calculate the relative weight saving compared with the reference metallic pressure vessel. The determination of proper fiber orientation and laminate thickness is very important to decrease manufacturing difficulties and increase structural efficiency. In the present work different lay-up sequences for laminates including, cross-ply [ 0 m /90 n ] s , angle-ply [ ±?] ns , [ 90/±?] ns and [ 0/±?] ns , are analyzed. The lay-up sequence, orientation and laminate thickness (number of layers) are optimized for three candidate composite materials S-glass/epoxy, Kevlar/epoxy and Carbon/epoxy. Finite element analysis of composite pressure vessel is performed by using commercial finite element code ANSYS and utilizing the capabilities of ANSYS Parametric Design Language and Design Optimization module to automate the process of optimization. For verification, a code is developed in MATLAB based on classical lamination theory; incorporating Tsai-Wu failure criterion for first-ply failure (FPF). The results of the MATLAB code shows its effectiveness in theoretical prediction of first-ply failure strengths of laminated composite pressure vessels and close agreement with the FEA results. The optimization results shows that for all the composite material systems considered, the angle-ply [ ±?] ns is the optimum lay-up. For given fixed ply thickness the total thickness of laminate is obtained resulting in factor of safety slightly higher than two. Both Carbon/epoxy and Kevlar/Epoxy resulted in approximately same laminate thickness and considerable percentage of weight saving, but S-glass/epoxy resulted in weight increment.

Mian, Haris Hameed; Wang, Gang; Dar, Uzair Ahmed; Zhang, Weihong

2013-10-01

256

Optimization of Composite Material System and Lay-up to Achieve Minimum Weight Pressure Vessel  

NASA Astrophysics Data System (ADS)

The use of composite pressure vessels particularly in the aerospace industry is escalating rapidly because of their superiority in directional strength and colossal weight advantage. The present work elucidates the procedure to optimize the lay-up for composite pressure vessel using finite element analysis and calculate the relative weight saving compared with the reference metallic pressure vessel. The determination of proper fiber orientation and laminate thickness is very important to decrease manufacturing difficulties and increase structural efficiency. In the present work different lay-up sequences for laminates including, cross-ply [0 m /90 n ] s , angle-ply [±?] ns , [90/±?] ns and [0/±?] ns , are analyzed. The lay-up sequence, orientation and laminate thickness (number of layers) are optimized for three candidate composite materials S-glass/epoxy, Kevlar/epoxy and Carbon/epoxy. Finite element analysis of composite pressure vessel is performed by using commercial finite element code ANSYS and utilizing the capabilities of ANSYS Parametric Design Language and Design Optimization module to automate the process of optimization. For verification, a code is developed in MATLAB based on classical lamination theory; incorporating Tsai-Wu failure criterion for first-ply failure (FPF). The results of the MATLAB code shows its effectiveness in theoretical prediction of first-ply failure strengths of laminated composite pressure vessels and close agreement with the FEA results. The optimization results shows that for all the composite material systems considered, the angle-ply [±?] ns is the optimum lay-up. For given fixed ply thickness the total thickness of laminate is obtained resulting in factor of safety slightly higher than two. Both Carbon/epoxy and Kevlar/Epoxy resulted in approximately same laminate thickness and considerable percentage of weight saving, but S-glass/epoxy resulted in weight increment.

Mian, Haris Hameed; Wang, Gang; Dar, Uzair Ahmed; Zhang, Weihong

2013-01-01

257

Fracture-Mechanics Data Deduced from Thermal-Shock and Related Experiments with LWR Pressure-Vessel Material.  

National Technical Information Service (NTIS)

Pressurized water reactors (PWRs) are susceptible to certain types of hypothetical accidents that can subject the reactor pressure vessel to severe thermal shock, that is, a rapid cooling of the inner surface of the vessel wall. The thermal-shock loading,...

R. D. Cheverton D. A. Canonico S. K. Iskander S. E. Bolt P. P. Holz

1982-01-01

258

Coronary stent implantation changes 3-D vessel geometry and 3-D shear stress distribution  

Microsoft Academic Search

Mechanisms of in-stent restenosis are not fully understood. Shear stress is known to play a role in plaque and thrombus formation and is sensitive to changes in regional vessel geometry. Hence, we evaluated the regional changes in 3-D geometry and shear stress induced by stent placement in coronary arteries of pigs.Methods. 3-D reconstruction was performed, applying a combined angiographic and

Jolanda J. Wentzel; Deirdre M. Whelan; Willem J. van der Giessen; Heleen M. M. van Beusekom; Ivan Andhyiswara; Patrick W. Serruys; Cornelis J. Slager; Rob Krams

2000-01-01

259

Characteristics of Turbulent Premixed Flames under the Pressure Rising Process in a Closed Vessel  

NASA Astrophysics Data System (ADS)

In a closed vessel such as SI engines, the internal pressure increases due to dilatation during the combustion after the ignition. To clarify quantitative characteristics of turbulent premixed flames under the pressure rising process, direct numerical simulation (DNS) of turbulent premixed flames in a closed vessel at relatively high Reynolds number has been conducted. Detailed kinetic mechanism for hydrogen-air mixtures is used. Because of the local pressure rise, turbulence is enhanced at the unburnt side and flame surface is distorted, which results in increase of the flame surface. Heat release rate of each flame element is augmented since the pressure rise makes flame thickness thin. Under this pressure rising process, the flame thickness, the flame front curvature and the local heat release rate can be scaled by laminar flame thickness and the maximum heat release rate obtained from one dimensional DNS of laminar flame propagation by using averaged temperature in the unburnt region of the vessel as the inlet temperature. The tangential strain rate on the flame front can be scaled by Taylor micro scale averaged in the unburnt side. The local heat release rate is positively correlated with the curvature and the tangential strain. The time evolution of the flame surface area is also investigated quantitatively.

Fukushima, Naoya; Yenerdag, Basmil; Shimura, Masayasu; Tanahashi, Mamoru; Miyauchi, Toshio

2011-11-01

260

Dual Shell Pressure Balanced Reactor Vessel cooperative research and development agreement with Innotek, Inc., Final report  

SciTech Connect

The Department of Energy`s Office of Energy Research (OER) has provided support for the development of several chemical processes, including supercritical water oxidation, liquefaction, and aqueous hazardous waste destruction, where chemical and phase transformations are conducted at high pressure and temperature. These and many other commercial processes require a pressure vessel capable of operating in a corrosive environment where safety and economy are important requirements. This document details a cooperative research and development agreement for a novel Dual Shell Pressure Balanced Vessel (DSPBV) which could solve a number of these problems. The Technology could be immediately useful in continuing commercialization of an R&D 100 award-winning technology, Sludge-to-oil Reactor System (STORS), originally developed through funding by OER.

Robertus, R.J.; Fassbender, A.G.; Deverman, G.S.

1995-04-01

261

Assessment of fire damage to pressure vessels in a refinery unit  

SciTech Connect

A systematic approach is proposed to assess the fitness of pressure vessels in the alkylation unit of a refinery after fire damage. Techniques used to study a Jan. 11, 1991, fire included in-situ metallography; hardness testing; crack detection; and measurements of thicknesses, plumb, circumference, and straightness. Emphasis is placed not on conventional techniques such as hardness testing and in-situ metallography, but on methods of measuring the affected vessels and effectively detecting and sizing distortions caused by the fire. Though these methods have been available in the past, they are not used in typical damage assessments.

Hau, J.L. (Petroleos de Venezuela, Curacao (Netherlands Antilles))

1993-05-01

262

Report No. 1 -- Review of procedures in the U. K. for the assessment of reactor pressure vessel integrity  

SciTech Connect

There is one pressurized water reactor (PWR) in the U.K., at Sizewell, which is currently under construction. There are several steel MAGNOX gas-cooled reactors in operation. The MAGNOX reactor operates at a lower pressure than a PWR, and has a large, relatively thin-walled ferritic steel reactor pressure vessel. The wall thickness is typically between 3 to 4.5 in. There is currently no formalized code or standard in the U.K. to which reactor pressure vessels are designed and operated. Guidelines have been published and these will be reviewed in this document. This document will present the current industry practice in the U.K. for assessing the integrity of steel reactor pressure vessels. The findings and recommendations in the second report from the Marshall Study Group on the Integrity of Pressurized Water Reactor Pressure Vessels are given particular emphasis.

Scarth, D.A. (Ontario Hydro, Mississauga, ON (Canada))

1993-11-01

263

Next Generation Nuclear Plant Reactor Pressure Vessel Materials Research and Development Plan (PLN-2803)  

SciTech Connect

The U.S. Department of Energy has selected the High Temperature Gas-cooled Reactor design for the Next Generation Nuclear Plant (NGNP) Project. The NGNP will demonstrate the use of nuclear power for electricity and hydrogen production. It will have an outlet gas temperature in the range of 900°C and a plant design service life of 60 years. The reactor design will be a graphite moderated, helium-cooled, prismatic, or pebble-bed reactor and use low-enriched uranium, Tri-Isotopic-coated fuel. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during accidents. The NGNP Materials Research and Development Program is responsible for performing research and development on likely NGNP materials in support of the NGNP design, licensing, and construction activities. Selection of the technology and design configuration for the NGNP must consider both the cost and risk profiles to ensure that the demonstration plant establishes a sound foundation for future commercial deployments. The NGNP challenge is to achieve a significant advancement in nuclear technology while setting the stage for an economically viable deployment of the new technology in the commercial sector soon after 2020. Studies of potential Reactor Pressure Vessel (RPV) steels have been carried out as part of the pre-conceptual design studies. These design studies generally focus on American Society of Mechanical Engineers (ASME) Code status of the steels, temperature limits, and allowable stresses. Three realistic candidate materials have been identified by this process: conventional light water reactor RPV steels A508/533, 2¼Cr-1Mo in the annealed condition, and modified 9Cr 1Mo ferritic martenistic steel. Based on superior strength and higher temperature limits, the modified 9Cr-1Mo steel has been identified by the majority of design engineers as the preferred choice for the RPV. All of the vendors have concluded, however, that with adequate engineered cooling of the vessel, the A508/533 steels are also acceptable.

J. K. Wright; R. N. Wright

2008-04-01

264

Heat Transfer Characteristics for Practical Hydrogen Pressure Vessels Being Filled at High Pressure  

NASA Astrophysics Data System (ADS)

Experiments have been conducted to measure the rise in temperature of hydrogen and vessel wall during filling of commercially available, practical tanks to 35 and 70 MPa. Three test vessels with volumes 205, 130 and 39 liters are investigated. The filling time ranges from 5 to 20 minutes. The heat transfer process is modeled using a one-dimensional unsteady heat conduction equation for the wall coupled with a flow and heat balance for the compressed gas. The model requires heat transfer coefficients between the hydrogen and the wall and the wall and surrounding air. Values of 500 W/(m2K) during filling, 250 W/(m2K) after filling for the inside wall and 4.5 W/(m2K) for the outside tank wall are tentatively assumed based on results from a previous study on a smaller vessel. The measured temperatures for the hydrogen gas and the wall are in good agreement with the calculations.

Woodfield, Peter L.; Monde, Masanori; Takano, Toshio

265

Influence of mis-match of weld and base material creep properties on elevated temperature design of pressure vessels and piping  

Microsoft Academic Search

The stress and strain concentrations developed at the weldments during the long time operation of pressure vessels and piping at high temperature due to the mis-match in the creep properties of weldment constituents (weld, heat affected zone and base metal) are estimated using detailed finite element analysis. Three materials, viz. 2.25Cr 1Mo, SS 316 LN and modified 9Cr 1 Mo

P Chellapandi; S. C Chetal

2000-01-01

266

Biaxial loading effects on fracture toughness of reactor pressure vessel steel  

SciTech Connect

The preliminary phases of a program to develop and evaluate fracture methodologies for assessing crack-tip constraint effects on fracture toughness of reactor pressure vessel (RPV) steels have been completed by the Heavy-Section Steel Technology (HSST) Program. Objectives were to investigate effect of biaxial loading on fracture toughness, quantify this effect through existing stress-based, dual-parameter, fracture-toughness correlations, or propose and verify alternate correlations. A cruciform beam specimen with 2-D, shallow, through-thickness flaw and a special loading fixture was designed and fabricated. Tests were performed using biaxial loading ratios of 0:1 (uniaxial), 0.6:1, and 1:1 (equi-biaxial). Critical fracture-toughness values were calculated for each test. Biaxial loading of 0.6:1 resulted in a reduction in the lower bound fracture toughness of {approximately}12% as compared to that from the uniaxial tests. The biaxial loading of 1:1 yielded two subsets of toughness values; one agreed well with the uniaxial data, while one was reduced by {approximately}43% when compared to the uniaxial data. Results were evaluated using J-Q theory and Dodds-Anderson (D-A) micromechanical scaling model. The D-A model predicted no biaxial effect, while the J-Q method gave inconclusive results. When applied to the 1:1 biaxial data, these constraint methodologies failed to predict the observed reduction in fracture toughness obtained in one experiment. A strain-based constraint methodology that considers the relationship between applied biaxial load, the plastic zone width in the crack plane, and fracture toughness was formulated and applied successfully to the data. Evaluation of this dual-parameter strain-based model led to the conclusion that it has the capability of representing fracture behavior of RPV steels in the transition region, including the effects of out-of-plane loading on fracture toughness. This report is designated as HSST Report No. 150.

McAfee, W.J.; Bass, B.R.; Bryson, J.W. Jr.; Pennell, W.E. [Oak Ridge National Lab., TN (United States)

1995-03-01

267

Acute and chronic stress influence blood pressure variability in mice  

Microsoft Academic Search

There is evidence that alterations in heart rate and blood pressure variability (BPV) are associated with cardiovascular disease. We used a mice model to investigate the effects of acute and chronic stress on blood pressure variability (BPV) and heat rate variability (HRV). Shaker stress was given acutely (5 min, 150 cycles\\/min) and chronically (3 days, 2 min stress, 150 cycles\\/min,

Vera M. A. Farah; Luis F. Joaquim; Iveta Bernatova; Mariana Morris

2004-01-01

268

Dosimetry assessments for the reactor pressure vessel and core barrel in UK PWR plant  

SciTech Connect

Specimens for the Sizewell B reactor pressure vessel (RPV) inservice steels surveillance program are irradiated inside eight capsules located within the reactor pressure vessel and loaded prior to commissioning. The periodic removal of these capsules and testing of their contents provides material properties data at intervals during the lifetime of the plant. Neutron activation measurements and radiation transport calculations play an essential role in assessing the neutron exposure of the specimens and RPV. Following the most recent withdrawal, seven capsules have now been removed covering nine cycles of reactor operation. This paper summarizes the dosimetry results of the Sizewell B surveillance program obtained to date. In addition to an overview of the calculational methodology it includes a review of the measurements. Finally, it describes an extension of the methodology to provide dosimetry recommendations for the core barrel and briefly discusses the results that were obtained. (authors)

Thornton, D.A.; Allen, D.A.; Huggon, A.P.; Picton, D.J.; Robinson, A.T.; Steadman, R.J. [Serco, Rutherford House, Quedgeley, Gloucester, Gl2 4NF (United Kingdom); Seren, T.; Lipponen, M.; Kekki, T. [VTT, Technical Research Centre of Finland, Otakaari 3 K, P.O. BOX 1000, Espoo, FI-02044 (Finland)

2011-07-01

269

Dynamics of cryogenic hydrogen storage in insulated pressure vessels for automotive applications  

Microsoft Academic Search

A dynamic model is used to characterize cryogenic H2 storage in an insulated pressure vessel that can flexibly hold liquid H2 and compressed H2 at 350bar. A double-flow refueling device is needed to ensure that the tank can be consistently refueled to its theoretical capacity regardless of the initial conditions. Liquid H2 charged into the tank is stored as supercritical

R. K. Ahluwalia; J. K. Peng

2008-01-01

270

High-density automotive hydrogen storage with cryogenic capable pressure vessels  

Microsoft Academic Search

LLNL is developing cryogenic capable pressure vessels with thermal endurance 5–10 times greater than conventional liquid hydrogen (LH2) tanks that can eliminate evaporative losses in routine usage of (L)H2 automobiles. In a joint effort BMW is working on a proof of concept for a first automotive cryo-compressed hydrogen storage system that can fulfill automotive requirements on system performance, life cycle,

Salvador M. Aceves; Francisco Espinosa-Loza; Elias Ledesma-Orozco; Timothy O. Ross; Andrew H. Weisberg; Tobias C. Brunner; Oliver Kircher

2010-01-01

271

Low-temperature fracture mechanisms in a spheroidised reactor pressure vessel steel  

Microsoft Academic Search

The micromechanisms of fracture of a spheroidised A533B reactor pressure vessel steel over the temperature range of ?190°C\\u000a to + 60°C were investigated by performing uniaxial tensile tests on double-notched cylindrical specimens. Failure was by quasi-cleavage\\u000a at temperatures between ?190°C and ?145°C. Quasi-cleavage fracture surfaces are characterised by clusters of planar facets\\u000a that are separated from other facets either by large

A. Kumar; S. G. Roberts; A. J. Wilkinson

2007-01-01

272

Investigation of black spots and other blemishes inside small stainless steel pressure vessels  

SciTech Connect

Black spots and other blemishes were found on the inside surface of small stainless steel pressure vessels by borescope inspection. Most of the black spots originated from pyrolysis of lint contaminating the interior surface of these parts prior to welding. The lint originated from cotton gloves used to handle parts and from cotton gauze used to clean the parts. Pyrolysis of other hydrocarbons can also create black spots. 34 figs.

Heiple, C.R.; Doyle, J.H.; Burgardt, P.

1990-08-14

273

Pressure vessel sliding support unit and system using the sliding support unit  

DOEpatents

Provided is a sliding support and a system using the sliding support unit. The sliding support unit may include a fulcrum capture configured to attach to a support flange, a fulcrum support configured to attach to the fulcrum capture, and a baseplate block configured to support the fulcrum support. The system using the sliding support unit may include a pressure vessel, a pedestal bracket, and a plurality of sliding support units.

Breach, Michael R.; Keck, David J.; Deaver, Gerald A.

2013-01-15

274

Role of crack arrest in the evaluation of PWR pressure vessel integrity during PTS transients  

Microsoft Academic Search

The HSST program is investigating flaw behavior in large cylinders and is also obtaining fracture-mechanics-related material properties, while the Integrated Pressurized Thermal-Shock (IPTS) program is primarily concerned with an estimation of the overall frequency of vessel failure and identification of dominant transients and design and operating features contributing thereto for specific nuclear plants. One important component of the IPTS study

R. D. Cheverton; D. G. Ball

1984-01-01

275

Ultrasonic NDE of Kevlar-epoxy filament wound spherical pressure vessels  

SciTech Connect

The nondestructive evaluation of Kevlar-epoxy filament wound spherical composite pressure vessels is performed through the use of a six axis rotatorially articulated robotic manipulator. Ultrasonic pulse-echo techniques are employed to form C-scan images based upon amplitude and attenuation data gathered by a 68000 based microcomputer system. The data are imaged in planar and three dimensional forms and are further enhanced and analyzed through image processing techniques specifically developed for the analysis of complex composite structures. 25 figs.

Blake, R.A.; Steiner, K.V.

1985-10-01

276

2 1/4 Cr-1 Mo steels for coal-conversion pressure vessels. [Tempering; hydrogen  

SciTech Connect

Pressure vessels for coal conversion processes are likely to be made of a 2 1/4 Cr-1 Mo steel, covered by ASTM specification A387, class 2, grade 22. Under the projected operating conditions, degradation of the mechanical properties of the steel by temper embrittlement, hydrogen embrittlement and hydrogen attack is a major concern. The significance of these degradation mechanisms is reviewed in the light of experimental results recently generated by EPRI projects and other results published in the literature.

Viswanathan, R.; Jaffee, R.I.

1981-11-01

277

2 1/4Cr-1Mo steels for coal conversion pressure vessels  

SciTech Connect

Pressure vessels for coal conversion processes are likely to be made of a 2 1/4 Cr-1 Mo steel, covered by ASTM specification A387, class 2, grade 22. Under the projected operating conditions, degradation of the mechanical properties of the steel by temper embrittlement and hydrogen embrittlement is a major concern. The significance of these degradation mechanisms is reviewed here in the light of experimental results recently generated by EPRI projects and other results published in the literature. 39 refs.

Viswanathan, R.; Jaffee, R.I.

1982-07-01

278

Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.  

SciTech Connect

Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K{sub THi}* is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; K{sub THa} is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K{sub JH} is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K{sub THi}*, and the crack arrest threshold, K{sub THa}, were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustained-load cracking tests under constant displacement. In contrast, K{sub JH}, which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which sub-critical crack extension is driven by internal hydrogen gas pressure.

Nibur, Kevin A.

2010-11-01

279

Stress-strain measurements and viscoelastic response of blood vessels cryopreserved by vitrification.  

PubMed

To gain increased insight into thermo-mechanical phenomena during cryopreservation, tensile stress relaxation experiments were conducted on vitrified blood vessels (vitreous in Latin means Glassy), and the results compared with various viscoelastic models. Using a recently presented device, isothermal stress-relaxation results were obtained for a bovine carotid artery model, permeated with the cryoprotectant cocktail VS55 and a reference solution of 7.05 M DMSO. After a rapidly applied tensile strain, experimental results display exponential decay of stress with time; the stress at a given time increases with decreasing specimen temperature. Among the viscoelastic models investigated, the Williams-Landel-Ferry model was found to best-fit the variation of the stress relaxation data with temperature, while a Maxwell-Weichert model is used to represent the exponential decay of the stress with time. Blood vessel properties were found to dominate at temperatures above roughly -100 degrees C, while the properties of the cryoprotectant dominate below this temperature. A suitably defined steady-state viscosity displayed a similar behavior for both cryoprotectants, when normalized with respect to the cryoprotectant glass transition temperature. PMID:17828592

Jimenez Rios, Jorge L; Steif, Paul S; Rabin, Yoed

2007-09-09

280

Fabrication Flaw Density and Distribution In Repairs to Reactor Pressure Vessel and Piping Welds  

SciTech Connect

The Pacific Northwest National Laboratory is developing a generalized fabrication flaw distribution for the population of nuclear reactor pressure vessels and for piping welds in U.S. operating reactors. The purpose of the generalized flaw distribution is to predict component-specific flaw densities. The estimates of fabrication flaws are intended for use in fracture mechanics structural integrity assessments. Structural integrity assessments, such as estimating the frequency of loss-of-coolant accidents, are performed by computer codes that require, as input, accurate estimates of flaw densities. Welds from four different reactor pressure vessels and a collection of archived pipes have been studied to develop empirical estimates of fabrication flaw densities. This report describes the fabrication flaw distribution and characterization in the repair weld metal of vessels and piping. This work indicates that large flaws occur in these repairs. These results show that repair flaws are complex in composition and sometimes include cracks on the ends of the repair cavities. Parametric analysis using an exponential fit is performed on the data. The relevance of construction records is established for describing fabrication processes and product forms. An analysis of these records shows there was a significant change in repair frequency over the years when these components were fabricated. A description of repair flaw morphology is provided with a discussion of fracture mechanics significance. Fabrication flaws in repairs are characterized using optimized-access, high-sensitivity nondestructive ultrasonic testing. Flaw characterizations are then validated by other nondestructive evaluation techniques and complemented by destructive testing.

GJ Schuster, FA Simonen, SR Doctor

2008-04-01

281

Response Margins Investigation of Piping Dynamic Analyses Using the Independent Support Motion Method and PVRC (Pressure Vessel Research Committee) Damping.  

National Technical Information Service (NTIS)

An evaluation of Independent Support Motion (ISM) response spectrum methods of analysis coupled with the Pressure Vessel Research Committee (PVRC) recommendation for damping, to compute the dynamic component of the seismic response of piping systems, was ...

M. Reich P. Bezler Y. K. Wang

1988-01-01

282

Reactor Pressure Vessel Steels Asme sa 533B and SA508.C1.2: Microstructural Investigations.  

National Technical Information Service (NTIS)

The as-quenched and variably tempered microstructures of pressure vessel steels were studied with optical, scanning and transmission electron microscopes. The microstructure consists mainly of granular bainite. Tempering transforms the martensite-austenit...

R. Pelli P. Nenonen M. Kemppainen K. Toerroenen

1983-01-01

283

Prestressed-concrete pressure vessels and their applicability to advanced-energy-system concepts  

SciTech Connect

Prestressed concrete pressure vessels (PCPVs) are, in essence, spaced steel structures since their strength is derived from a multitude of steel elements made up of deformed reinforcing bars and prestressing tendons which are present in sufficient quantities to carry tension loads imposed on the vessel. Other major components of a PCPV include the concrete, liner and cooling system, and insulation. PCPVs exhibit a number of advantages which make them ideally suited for application to advanced energy concepts: fabricability in virtually any size and shape using available technology, improved safety, reduced capital costs, and a history of proven performance. PCPVs have many applications to both nuclear- and non-nuclear-based energy systems concepts. Several of these concepts will be discussed as well as the research and development activities conducted at ORNL in support of PCPV development.

Naus, D.J

1983-01-01

284

RADIATION DOSIMETRY OF THE PRESSURE VESSEL INTERNALS OF THE HIGH FLUX BEAM REACTOR.  

SciTech Connect

In preparation for the eventual decommissioning of the High Flux Beam Reactor after the permanent removal of its fuel elements from the Brookhaven National Laboratory, both measurements and calculations of the decay gamma-ray dose rate have been performed for the reactor pressure vessel and vessel internal structures which included the upper and lower thermal shields, the transition plate, and the control rod blades. The measurements were made using Red Perspex{trademark} polymethyl methacrylate high-level film dosimeters, a Radcal ''peanut'' ion chamber, and Eberline's high-range ion chamber. To compare with measured gamma-ray dose rate, the Monte Carlo MCNP code and geometric progressive Microshield code were used to model the gamma transport and dose buildup.

HOLDEN,N.E.; RECINIELLO,R.N.; HU,J.P.; RORER,D.C.

2002-08-18

285

D-Zero Central Calorimeter Technical Appendix to Cryogenic Pressure Vessels  

SciTech Connect

DO (D Zero) is a large Liquid Argon (LAr) HEP Calorimeter designed to function in the laboratories P-Pbar collider at the DO section of the Tevatron accelerator. It contains 5,000 gls. of LAr in the CC cryostat, and 3,000 gls. in each of two, a north and south, EC cryostats. These low pressure vessels are filled with detector modules built of stainless steel, copper and depleted uranium. The LAr functions as the ionization medium, and the spatial and temporal of the collection of the charge of the electrons produced signals the passsage of charged particles. The collection of these charges in 4 pi is related to the energy of the particles, and their measurement is called calorimetry. The contained LAr (T=90K) is isolated from the ambient temperatures in specially designed, vacuum and superinsulated, vessels (cryostats) provided with liquid nitrogen, heat of vaporization, cooling.

Mulholland, G.T.; Rucinski, R.A.; /Fermilab

1990-11-19

286

Estimation of mechanical properties of irradiated nuclear pressure vessel steel by use of subsized CT specimen and small punch specimen  

Microsoft Academic Search

This paper reports on the 2-1\\/4 Cr-1Mâ steel that has been selected as the material for the reactor pressure vessel (RPV) of a multipurpose experimental high temperature gas cooled reactor designed by JAERI. The 2-1\\/4 Cr-1Mâ steel has successful records for high temperature pressure vessels in the petrochemical industries and the ASME Code Case authorizes the use of the steel

X. Mao; H. Takahashi; T. Kodaira

1991-01-01

287

Measuring occupational stress: Development of the Pressure Management Indicator  

Microsoft Academic Search

The study of occupational stress is hindered by the lack of compact and comprehensive standardized measurement tools. The Pressure Management Indicator (PMI) is a 120-item self-report questionnaire developed from the Occupational Stress Indicator (OSI). The PMI is more reliable, more comprehensive, and shorter than the OSI. It provides an integrated measure of the major dimensions of occupational stress. The outcome

Stephen Williams; Cary L. Cooper

1998-01-01

288

Solid-state track recorder neutron dosimetry in light water reactor pressure vessel surveillance mockups  

SciTech Connect

Solid-State Track Recorder (SSTR) measurements of neutron-induced fission rates have been made in several pressure vessel mockup facilities as part of the US Nuclear Regulatory Commission's (NRC) Light Water Reactor Pressure Vessel Surveillance Dosimetry Improvement Program (LWR-PV-SDIP). The results of extensive physics-dosimetry measurements made at the Pool Critical Assembly (PCA) at Oak Ridge National Laboratory (ORNL) in Oak Ridge, TN are summarized. Included are /sup 235/U, /sup 238/U, /sup 237/Np and /sup 232/Th fission rates in the PCA 12/13, 8/7, and 4/12 SSC configurations. Additional low power measurements have been made in an engineering mockup at the VENUS critical assembly at CEN-SCK, Mol, Belgium. /sup 237/Np and /sup 238/U fission rates were made at selected locations in the VENUS mockup, which models the in-core and near-core regions of a pressurized water reactor (PWR). Absolute core power measurements were made at VENUS by exposing solid-state track recorders (SSTRs) to polished fuel pellets within in-core fuel pins. 8 references, 4 figures, 10 tables.

Ruddy, F.H.; Roberts, J.H.; Gold, R.; Preston, C.C.

1984-09-01

289

Influence of pore pressure and production-induced changes in pore pressure on in situ stress  

SciTech Connect

Knowledge of in situ stress and how stress changes with reservoir depletion and pore pressure drawdown is important in a multi-disciplinary approach to reservoir characterization, reservoir management, and improved oil recovery projects. This report summarizes a compilation of in situ stress data from six fields showing the effects of pore pressure and production-induced changes in pore pressure on the minimum horizontal stress. The in situ stress data and corresponding pore pressure data were obtained from field records of the operating companies and published reports. Horizontal stress was determined from closure pressure data of hydraulic fractures and leak-off tests. The stress measurements clearly demonstrate that the total minimum-horizontal stress is dependent on pore pressure. A decrease in pore pressure either by geologic processes or production of a reservoir will result in a decrease in the total minimum-horizontal stress. The magnitude of changes in stress state with net changes in pore pressure is dependent on local field conditions and cannot be accurately predicted by the uniaxial strain model that is commonly used by the petroleum industry.

Teufel, L.W.

1996-02-01

290

Strength and life of pressure vessels subjected to impacts and thermomechanical GFRP loading  

NASA Astrophysics Data System (ADS)

Non-insulated GRFP (Glass Fiber Reinforced Plastics) pipes were experimentally investigated. Particular consideration was given to the effects of short term thermal overloads and impact damage. It was shown that for a matrix with a long term specified service temperature of less than 140 C and starting from 140 C at 10 bar pressure up to 200 C and 30 bar pressure up to 170 C such thermalcycling up to some 100 cycles is acceptable when the hold time at the peak temperature is less than one hour. A prerequisite for this is the outer surface of the pipes remaining non-insulated and cooler (by about 30 C) than the content. No significant creep strain under static 10 bar pressure at 140 C was measured up to 350 hours of testing time. At 200 C and 30 bar, creep was fast enough to produce failure in a few hours. Clearly, the matrix material is not well suited to these high temperatures. Nevertheless, temporary surges in inside temperature to 170 C or even relatively long periods peaking at 140 C should not cause significant problems at normal service pressures near 10 bar, at least up to some 100 cycles. Impact testing and subsequent static pressure testing showed that for a given type of material, the leakage pressure of the vessel can be relatively easily predicted from the incident impact energy or from the ultrasonically determined size of the impact defect.

Pankakoski, Pekka H.; Uuttu, Tero; Kauppinen, Pentti; Sarkimo, Matti; Auerkari, Pertti

1992-10-01

291

Review of the Palisades pressure vessel accumulated fluence estimate and of the least squares methodology employed  

SciTech Connect

This report provides a review of the Palisades submittal to the Nuclear Regulatory Commission requesting endorsement of their accumulated neutron fluence estimates based on a least squares adjustment methodology. This review highlights some minor issues in the applied methodology and provides some recommendations for future work. The overall conclusion is that the Palisades fluence estimation methodology provides a reasonable approach to a {open_quotes}best estimate{close_quotes} of the accumulated pressure vessel neutron fluence and is consistent with the state-of-the-art analysis as detailed in community consensus ASTM standards.

Griffin, P.J.

1998-05-01

292

Fatal and non-fatal injuries from vessels under air pressure in construction.  

PubMed

Using a surveillance system that captures data on construction workers treated in an urban emergency department, we identified a series of injuries caused by vessels and tools under air pressure. We describe those six cases, as well as similar cases found in the Census of Fatal Occupational Injuries; we also review data from the National Surveillance for Traumatic Occupational Fatalities database and data from the Bureau of Labor Statistics. Among the injuries and deaths for which we had good case descriptions, the majority would have been prevented by adherence to existing Occupational Safety and Health Administration standards in the construction industry. PMID:10029954

Welch, L S; Weeks, J; Hunting, K L

1999-02-01

293

Supplementary neutron-flux calculations for the ORNL Pool Critical Assembly Pressure Vessel Facility  

SciTech Connect

A three-dimensional Monte Carlo calculation using the MORSE code was performed to validate a procedure previously adopted in the ORNL discrete ordinate analysis of measurements made in the ORNL Pool Critical Assembly Pressure Vessel Facility. The results of these flux calculations agree, within statistical undertainties of about 5%, with those obtained from a discrete ordinate analysis employing the same procedure. This study therefore concludes that the procedure for combining several one- and two-dimensional discrete ordinate calculations into a three-dimensional flux is sufficiently accurate that it does not account for the existing discrepancies observed between calculations and measurements in this facility.

Maudlin, P.J.; Maerker, R.E.

1982-01-01

294

A structural evaluation of the Shippingport reactor pressure vessel for transport impact conditions  

SciTech Connect

The Shippingport Atomic Power Station in Shippingport, Pennsylvania, is being decommissioned and dismantled. This government-leased property will be returned, in a radiologically safe condition, to its owner. All radioactive material is being removed from the Shippingport Station and transported for burial to the DOE Hanford Reservation in Richland, Washington. The reactor pressure vessel (RPV) will be transported by barge to Hanford. This paper describes an evaluation of the structural response of the RPV to the normal and accident impact test conditions as required by the Code of Federal Regulations. 3 refs., 5 figs., 3 tabs.

Witte, M.C.; Chou, C.K.

1989-03-24

295

Stress and Thermal Analysis of the In-Vessel RMP Coils in HL-2M  

NASA Astrophysics Data System (ADS)

A set of in-vessel resonant magnetic perturbation (RMP) coils for MHD instability suppression is proposed for the design of a HL-2M tokamak. Each coil is to be fed with a current of up to 5 kA, operated in a frequency range from DC to about 1 kHz. Stainless steel (SS) jacketed mineral insulated cables are proposed for the conductor of the coils. In-vessel coils must withstand large electromagnetic (EM) and thermal loads. The support, insulation and vacuum sealing in a very limited space are crucial issues for engineering design. Hence finite element calculations are performed to verify the design, optimize the support by minimizing stress caused by EM forces on the coil conductors and work out the temperature rise occurring on the coil in different working conditions, the corresponding thermal stress caused by the thermal expansion of materials is evaluated to be allowable. The techniques to develop the in-vessel RMP coils, such as support, insulation and cooling, are discussed.

Cen, Yishun; Li, Qiang; Ding, Yonghua; Cai, Lijun; Jiang, Jiaming; Li, Guangsheng; Liu, Yi

2013-09-01

296

Characteristics of the turbulent boundary layer pressure spectra for high-speed vessels  

NASA Astrophysics Data System (ADS)

Recent studies demonstrate that the fluctuating pressure field generated by the turbulent boundary layer (TBL) is an important flow noise source for high-speed marine vehicles. In fact, wall-pressure fluctuations induce vibrations in the hull plates of the vessel that are responsible for undesirable noise on board. In this framework, the correct description of the pressure load acting on the hull needs a deep knowledge of its spectral features and, in this work, the problem of the power spectral density characterization is analysed. This quantity is usually obtained experimentally, because of limitations of the available computational resources at the high Reynolds numbers typical of engineering applications. However, the experimental evaluation of the power spectral density presents as well some problems because of the low frequency pollution due to the background noise of the facilities and because of the high frequency attenuation due to the finite size of the pressure sensors. Boundary-layer characteristics depend, for a body moving in an unbounded flow, on the Reynolds number, while, in the case of a surface ship, a Froude number dependency must be taken into account. In view of the evaluation of the noise level on board of civil high-speed vessels generated by flow-induced vibrations, an experimental campaign aimed at measuring the pressure fluctuations beneath the TBL attached to the hull of a ship model was performed in a towing tank. The use of this facility, new for this kind of experiments, provides ideal flow conditions because background noise and turbulence are absent. Pressure signals are acquired for a large range of Reynolds numbers by varying both the model velocity and the test-section along the hull length. With this experimental set-up it was possible to analyse the details of the pressure spectra in the different frequency regions. In this work, a detailed discussion on the pressure scaling laws is provided together with a critical comparison with the available results obtained for different facilities and experimental conditions.

Ciappi, E.; Magionesi, F.

2005-11-01

297

Damage dosimetry and embrittlement monitoring of nuclear pressure vessels in real time by magnetic properties measurement  

NASA Astrophysics Data System (ADS)

This program developed a nondestructive technique for gauging the progress of embrittlement of nuclear pressure vessel steels (PVS) by means of monitoring radiation-induced changes in magnetic properties. The technique was developed by running a series of experiments in reactor on typical nuclear pressure vessel steels and weldment material. Following irradiation, changes in magnetic properties were measured and correlated with irradiation dose and with mechanical properties changes, where possible. The changes in magnetic properties were unique to the irradiation environment, and were much larger than those produce by thermal aging in the absence of irradiation. Special techniques for magnetic properties change measurement were developed and complimented by more standard magnetic properties measurement techniques including SQUID measurements. The results of the experiments revealed that magnetic properties were very sensitive to irradiation. Changes in microstructurally-related magnetic properties of as much as 40% were noted after irradiation exposure of as little as 10(exp 17) n/sq cm (E greater than 0.1 MeV). The magnetic properties changes plateaued out after doses of around as 10(exp 18) n/cm(sup 2) (E greater than 0.1 MeV). It is unclear whether further changes would be noted at higher doses which would also be useful for tracking the embrittlement phenomenon. This is recommended for further study. The work supported here resulted in several publications in the open scientific literature.

Ougouag, A. M.; Stubbins, J. F.; Williams, J. F.; Shong, Wei-Ja

1995-04-01

298

Assessment of Radiation Embrittlement in Nuclear Reactor Pressure Vessel Surrogate Materials  

NASA Astrophysics Data System (ADS)

The radiation-enhanced formation of small (1-2 nm) copper-rich precipitates (CRPs) is critical for the occurrence of embrittlement in nuclear-reactor pressure vessels. Small CRPs are coherent with the bcc matrix, which causes local matrix strain and interaction with the dislocation strain fields, thus impeding dislocation mobility. As CRPs grow, there is a critical size at which a phase transformation occurs, whereby the CRPs are no longer coherent with the matrix, and the strain is relieved. Diffraction-line-broadening analysis (DLBA) and small-angle neutron scattering (SANS) were used to characterize the precipitate formation in surrogate ferritic reactor-pressure vessel steels. The materials were aged for different times at elevated temperature to produce a series of specimens with different degrees of copper precipitation. SANS measurements showed that the precipitate size distribution broadens and shifts toward larger sizes as a function of ageing time. Mechanical hardness showed an increase with ageing time, followed by a decrease, which can be associated with the reduction in the number density as well as the loss of coherency at larger sizes. Inhomogeneous strain correlated with mechanical hardness.

Balzar, Davor

2010-10-01

299

Helium leak testing of a radioactive contaminated vessel under high pressure in a contaminated environment  

SciTech Connect

At ANL-W, with the shutdown of EBR-II, R&D has evolved from advanced reactor design to the safe handling, processing, packaging, and transporting spent nuclear fuel and nuclear waste. New methods of processing spent fuel rods and transforming contaminated material into acceptable waste forms are now in development. Storage of nuclear waste is a high interest item. ANL-W is participating in research of safe storage of nuclear waste, with the WIPP (Waste Isolation Pilot Plant) site in New Mexico the repository. The vessel under test simulates gas generated by contaminated materials stored underground at the WIPP site. The test vessel is 90% filled with a mixture of contaminated material and salt brine (from WIPP site) and pressurized with N2-1% He at 2500 psia. Test acceptance criteria is leakage < 10{sup -7} cc/seconds at 2500 psia. The bell jar method is used to determine leakage rate using a mass spectrometer leak detector (MSLD). The efficient MSLD and an Al bell jar replaced a costly, time consuming pressure decay test setup. Misinterpretation of test criterion data caused lengthy delays, resulting in the development of a unique procedure. Reevaluation of the initial intent of the test criteria resulted in leak tolerances being corrected and test efficiency improved.

Winter, M.E.

1996-10-01

300

Computational experiments; Proceedings of the ASME/JSME Pressure Vessels and Piping Conference, Honolulu, HI, July 23-27, 1989  

NASA Astrophysics Data System (ADS)

Papers applying FEM to engineering problems are presented, covering topics such as a numerical approach to software development for thermoforming simulations, flow three-dimensional analysis of pressure responses in an enclosed launching system, comparing flow three-dimensional calculations with very large amplitude slosh data, and the computational analysis of stress concentrations in pressure vessel cascades. Other topics include FEM studies of flow past an array of plates, stochastic finite elements for automotive impact, numerical simulation in the deployment of space structures, axial buckling of a thin cylindrical shell, applying FEM to the prediction of vibrations of liquid propelled launch vehicles, analysis of a large bore piping system supported with viscodampers, stochastic simulation of lubricant depletion on a magnetic storage disk, and two-dimensional crak inclusion interaction effects. Additional topics include analyzing damage mechanisms using the energy release rate, the suspension of solid particles in an aerospace plane's slush hydrogen tanks, modal methods for the analysis of vibrations of structures coupled with fluids, the elastic-plastic behavior of fibrous metal matrix composites, and stochastic finite element analysis of nonlinear media.

Liu, W. K.; Smolinski, P.; Ohayon, R.; Navickas, J.; Gvildys, J.

1989-06-01

301

Circadian Blood Pressure Patterns and Life Stress  

Microsoft Academic Search

Background: Scarce data are available on the influence of psychological aspects on 24-hour ambulatory blood pressure patterns either in normotensive or hypertensive subjects. This study was designed to evaluate the relationship between psychological profile and changes in daytime\\/nighttime blood pressure rhythm. Methods:Nocturnal dipping was defined as the night\\/day ratio of ambulatory mean systolic and\\/or diastolic blood pressure ?0.87. Three-hundred and

Francesco Fallo; Luisa Barzon; Franco Rabbia; Cecilia Navarrini; Andrea Conterno; Franco Veglio; Manuela Cazzaro; Giovanni A. Fava; Nicoletta Sonino

2002-01-01

302

Temperature and pressure influence on maximum rates of pressure rise during explosions of propane–air mixtures in a spherical vessel  

Microsoft Academic Search

The maximum rates of pressure rise during closed vessel explosions of propane–air mixtures are reported, for systems with various initial concentrations, pressures and temperatures ([C3H8]=2.50–6.20vol.%, p0=0.3–1.3bar; T0=298–423K). Experiments were performed in a spherical vessel (?=10cm) with central ignition. The deflagration (severity) index KG, calculated from experimental values of maximum rates of pressure rise is examined against the adiabatic deflagration index,

D. Razus; V. Brinzea; M. Mitu; C. Movileanu; D. Oancea

2011-01-01

303

Effect of the Blood Vessel Viscoelasticity on Periodic Blood Pressure Wave Propagation  

NASA Astrophysics Data System (ADS)

Clinical arterial stiffness indexes such as PWV (pulse wave velocity) or PP (pulse pressure), which are obtained by analyzing blood pressure pulse waveforms in vivo, are used in the prognosis of cardiovascular diseases and thus analyses of pulse waveform are clinically important. The pulse wave in vivo, however, is complicated because of the complex viscoelastic property of the blood vessel wall. In addition, numerical flow simulations are useful for understanding pulse wave propagation in circulatory systems. Our proposed nonlinear one-dimensional numerical simulation model can accurately simulate the measurements of pressure waves in a silicone rubber tube and indicate that the viscoelasticity of the tube wall was significantly influenced by a single pulse waveform; however, the influence of viscoelasticity change on periodic pulsatile wave propagation has not yet been studied. The purpose of this study was therefore to investigate the effect of viscoelasticity change on the periodic pulsatile wave. For this purpose, we examined the effect of the viscoelasticity of a single silicone tube on periodic pulse wave propagation by comparing the calculated results using a one-dimensional model. As a result, the one-dimensional model could accurately express the experimental results with periodic pulsatile waves. In addition, both PWV and PP increase when the viscoelastic value of the dynamic modulus elasticity ratio increases, because increasing the elastic modulus is more effective than the energy dissipation effect by viscoelasticity change. Consequently, it is necessary to measure the viscoelastic property of the vessel wall accurately in order to estimate the arterial stiffness index (PWV and PP) accurately.

Kitawaki, Tomoki; Shimizu, Masashi

304

An investigation of cladding effects on shallow-flaw fracture toughness of reactor pressure vessel steel under prototypic biaxial loading  

SciTech Connect

Potential structural-integrity benefits or liabilities of the stainless steel cladding on the inner surface of a reactor pressure vessel (RPV) are important considerations in the effort to refine or improve safety assessment procedures applied to RPVs. Clad-beam tests were carried out to investigate and quantify effects of the clad structure on fracture initiation toughness of through-clad shallow surface flaws in RPV material. A cruciform beam specimen was developed at ORNL to introduce a prototypic, far-field, out-of-plane biaxial stress component that provides a linear approximation of the nonlinear stress distribution generated by thermo-mechanical loading transients in an RPV. The cruciform specimens (102-mm-thick test section) were fabricated from RPV shell segments available from a canceled pressurized-water reactor plant. The specimens were tested under biaxial load ratios ranging from 0.0 (uniaxial) to 1.0 (full biaxial), the ratio being defined as the total load applied to the transverse beam arms divided by that applied to the longitudinal arms. The test results imply that biaxial loading is effective in reducing the shallow-flaw fracture toughness of the clad/heat-affected zone/structural-weld region of the RPV shell below that determined from uniaxial loading conditions. The lowest toughness value from the clad cruciform specimens tested under biaxial loading is only slightly above the ASME Section XI K{sub lc} curve. For all biaxiality ratios, the test results imply that shallow-flaw fracture toughness data from the RPV structural weld material are significantly lower than that obtained from a high-yield strength plate material.

Bass, B.R.; McAfee, W.J.; Bryson, J.W.; Pennell, W.E. [Oak Ridge National Lab., TN (United States). Heavy Section Steel Technology Program

1999-08-01

305

Comparison of fracture toughness and Charpy impact properties recovery by thermal annealing of irradiated reactor pressure vessel steels  

Microsoft Academic Search

The objective of this investigation was to study the effects of thermal annealing on the recovery of the transition region toughness of reactor pressure vessel steels. The toughness was measured by Charpy V-notch impact energy and fracture initiation toughness, K{sub Jc}. The materials were A 533 grade B class 1 plate and a commercial reactor vessel submerged-arc weld irradiated at

M. A. Sokolov; D. E. McCabe; S. K. Iskander; R. K. Nanstad

1995-01-01

306

Low-alloy steels for thick-walled pressure vessels. Summary report, February 1, 1980January 31, 1982  

Microsoft Academic Search

This program aimed to modify existing commercial pressure vessel steels to provide strong, tough, creep resistant materials, with low hydrogen attack and temper embrittlement susceptibilities, which can also be field-fabricated into thick-section vessels for coal conversion systems. Emphasis was placed on determining the effects of Mn, Ni and Cr on the creep rupture and hydrogen attack susceptibilities of Cr-Mo steels.

J. A. Todd; D. W. Chung; E. R. Parker

1982-01-01

307

Pore-pressure gradients, stresses, and induced earthquakes  

SciTech Connect

In the theory of poroelasticity, spatial gradients in pore-pressure enter the equilibrium equations in the same way as distributed body forces. Pore-pressure gradients are thus associated with poroelastic stresses in the same way that temperature gradients associated with thermoelastic stresses. The author has suggested that pore-pressure gradients caused by pumping are responsible for earthquakes near some oil and gas fields. Seismic data from a number of active oil and gas fields in California, Texas, Alberta, and elsewhere clearly show that earthquakes are occurring near fields where pore pressures have declined by several 10's of MPa. These observations can not be explained by changes in effective stress alone, which predicts that decreasing pore-fluid pressures tend to stabilize faults. He believes that poro-elastic stresses resulting from pore-fluid extraction are responsible for earthquakes in these situations. Fluid injection also induces poro-elastic stresses, however it is difficult to separate this effect from the destabilizing effect of increased pore-pressure within fault zones. To test the poroelastic model for induced seismicity, theoretical predictions are compared to data from a deep gas field in the Pyrenean foreland. Hundreds of shallow, small to moderate earthquakes have occurred there since 1969. The earthquakes are tightly clustered near the gas field. Reservoir pressure had declined by 30 MPa at the onset of seismicity. The relationship between average reservoir pressure decline and subsidence is remarkably linear, lending support to the linear poroelastic model. Using laboratory derived material parameters and in situ reservoir pressure measurements, it is possible to predict the surface deformations and the change in stress field without adjustable parameters. The computed vertical displacements are in good agreement with the observed subsidence. The poroelastic stress changes at the onset of seismicity are of the order of a few bars.

Segall, P. (Stanford Univ., CA (United States). Geophysics Dept. Geological Survey, Menlo Park, CA (United States))

1992-01-01

308

Report No. 1 -- Review of procedures in the U. K. for the assessment of reactor pressure vessel integrity  

Microsoft Academic Search

There is one pressurized water reactor (PWR) in the U.K., at Sizewell, which is currently under construction. There are several steel MAGNOX gas-cooled reactors in operation. The MAGNOX reactor operates at a lower pressure than a PWR, and has a large, relatively thin-walled ferritic steel reactor pressure vessel. The wall thickness is typically between 3 to 4.5 in. There is

Scarth

1993-01-01

309

Volume Change during Deformation and Pressure Dependence of Yield Stress  

Microsoft Academic Search

Polymers are distinguished from metals by the considerable pressure dependence of their yield stresses, and one might expect this to be associated with a plastic volume change during yielding. We have measured the macroscopic volume changes during uniaxial compression of PMMA and PC, using a mercury-filled dilatometer. For PMMA a plastic volume change cannot be defined unambiguously because the volume-stress

C. A. Pampillo; L. A. Davis

1971-01-01

310

Blood Pressure Variability and Stress Management Training for Essential Hypertension  

ERIC Educational Resources Information Center

|The purpose of this study was to determine whether stress management training reduces blood pressure (BP) variability in hypertensive patients. Previous literature suggests that cardiovascular risk is not only a function of BP levels, but also of BP variability, and this partially depends on changes induced by the stress of everyday life. The…

Garcia-Vera, Maria Paz; Sanz, Jesus; Labrador, Francisco J.

2004-01-01

311

Survey of welding processes for field fabrication of 2 1/4 Cr-1 Mo steel pressure vessels. [128 references  

SciTech Connect

Any evaluation of fabrication methods for massive pressure vessels must consider several welding processes with potential for heavy-section applications. These include submerged-arc and shielded metal-arc, narrow-joint modifications of inert-gas metal-arc and inert-gas tungsten-arc processes, electroslag, and electron beam. The advantage and disadvantages of each are discussed. Electroslag welding can be dropped from consideration for joining of 2 1/4 Cr-1 Mo steel because welds made with this method do not provide the required mechanical properties in the welded and stress relieved condition. The extension of electron-beam welding to sections as thick as 4 or 8 inches (100 or 200 mm) is too recent a development to permit full evaluation. The manual shielded metal-arc and submerged-arc welding processes have both been employed, often together, for field fabrication of large vessels. They have the historical advantage of successful application but present other disadvantages that make them otherwise less attractive. The manual shielded metal-arc process can be used for all-position welding. It is however, a slow and expensive technique for joining heavy sections, requires large amounts of skilled labor that is in critically short supply, and introduces a high incidence of weld repairs. Automatic submerged-arc welding has been employed in many critical applications and for welding in the flat position is free of most of the criticism that can be leveled at the shielded metal-arc process. Specialized techniques have been developed for horizontal and vertical position welding but, used in this manner, the applications are limited and the cost advantage of the process is lost.

Grotke, G.E.

1980-04-01

312

Comparison of attenuation coefficients for VVER-440 and VVER-1000 pressure vessels  

SciTech Connect

The paper summarizes the attenuation coefficient of the neutron fluence with E > 0.5 MeV through a reactor pressure vessel for vodo-vodyanoi energetichesky reactor (VVER) reactor types measured and/or calculated for mock-up experiments, as well as for operated nuclear power plant (NPP) units. The attenuation coefficient is possible to evaluate directly only by using the retro-dosimetry, based on a combination of the measured activities from the weld sample and concurrent ex-vessel measurement. The available neutron fluence attenuation coefficients (E > 0.5 MeV), calculated and measured at a mock-up experiment simulating the VVER-440-unit conditions, vary from 3.5 to 6.15. A similar situation is used for the calculations and mock-up experiment measurements for the VVER-1000 RPV, where the attenuation coefficient of the neutron fluence varies from 5.99 to 8.85. Because of the difference in calculations for the real units and the mock-up experiments, the necessity to design and perform calculation benchmarks both for VVER-440 and VVER-1000 would be meaningful if the calculation model is designed adequately to a given unit. (authors)

Marek, M.; Rataj, J.; Vandlik, S. [Reactor Physics Dept., Research Centre Rez, Husinec 130, 25068 (Czech Republic)

2011-07-01

313

Boric acid corrosion of light water reactor pressure vessel head materials.  

SciTech Connect

This work presents experimental data on electrochemical potential and corrosion rates for the materials found in the reactor pressure vessel head and control rod drive mechanism (CRDM) nozzles in boric acid solutions of varying concentrations at temperatures of 95-316 C. Tests were conducted in (a) high-temperature, high-pressure aqueous solutions with a range of boric acid concentrations, (b) high-temperature (150-316 C)H-B-Osolutions at ambient pressure, in wet and dry conditions, and (c) low-temperature (95 C) saturated, aqueous, boric acid solutions. These correspond to the following situations: (a) low leakage through the nozzle and nozzle/head annulus plugged, (b) low leakage through the nozzle and nozzle/head annulus open, and (c) significant cooling due to high leakage and nozzle/head annulus open. The results showed significant corrosion only for the low-alloy steel and no corrosion for Alloy 600 or 308 stainless steel cladding. Also, corrosion rates were significant in saturated boric acid solutions, and no material loss was observed in H-B-O solution in the absence of moisture. The results are compared with the existing corrosion/wastage data in the literature.

Park, J.-H.; Chopra, O. K.; Natesan, K.; Shack, W. J.; Cullen, Jr.; W. H.; Energy Technology; USNRC

2005-01-01

314

Response of Soviet-designed VVER-440 steam generator vessel to pressurization  

SciTech Connect

The Soviet-designed VVER (Water-Cooled, Water-Moderated Energy Reactors) pressurized water reactors use horizontal steam generators to transfer energy from the primary to secondary coolant systems (DOE/NE-0084 Revision 2, 1989). Primary coolant flowing from the reactor vessel enters the steam generator through a vertical, circular, manifold header that also serves as the tubesheet distributing coolant to the horizontal tube bundle. Primary coolant exits the tube bundle and steam generator through a second similar vertical manifold header. The header design includes the provision for access by a person to inspect the mainfolds through bolted down closure heads atop each manifold. The internal diameter of each header exceeds that of the connected primary coolant system piping. The postulated failure of a manifold closure head or the manifold itself provides a pathway for primary coolant to enter the secondary system. Steam formation due to flashing of primary coolant inside the steam generator secondary side region can result in pressurization of the steam generator shell to values above the nominal secondary side operating pressure. The present work involves the investigation of the consequences of manifold failure for the case of the VVER-440 reactor system. An analysis has been performed of the loadings upon and the mechanical response of the steam generator shell for the case of a postulated large break in the manifold wall. The objectives were to calculate the maximum pressure attained inside the shell and to predict the shell failure pressure as well as the failure mechanism. 6 refs., 8 figs., 1 tab.

Kennedy, J.M.; Sienicki, J.J.

1989-01-01

315

Role of gas pressure and lateral stress on blistering  

SciTech Connect

Both gas pressure in bubbles and lateral stress have been suggested as primary causes of blistering. An analysis of both mechanisms is presented, and the conditions for blistering are examined. To realistically predict the gas pressure in bubbles, a recently derived high-density equation of state for helium is utilized.

Wolfer, W.G.

1980-04-01

316

Pressure and stress analysis for an underwater vehicle  

Microsoft Academic Search

Underwater vehicles are widely used in both military and civilian operations for more than 60 years. They are the best tools to perform dull, dangerous and dirty tasks in the water. So the distribution principles of static pressure and stress along the vehicle hull must be found out when designing hull shape and choosing the materials. The static pressure and

Yanhui Ai

2011-01-01

317

Manufacturing of Advanced Titanium (Lined) Propellant Tanks and High Pressure Vessels  

NASA Astrophysics Data System (ADS)

A modular titanium tank and liner manufacturing approach is presented. Special forgings with long lead time and important recurrent and non-recurrent cost are avoided. Starting with standard forms of supply, special forming methods allow for quick and cost efficient accommodation to the spacecraft requirements. Even propellant tanks for pressure-fed engines are proposed to be CFRP over-wrapped for mass savings reasons. Skirt mounting is realized by integral CFRP wrapping on the vessel's own over-wrap. Compatibility problems are hence avoided. The approach to apply standard forms of supply has been qualified for the first time with the ATV propellant tanks. It is currently expanded to the whole field of spacecraft tanks in terms of hardware demonstration and with respect to the related engineering effort.

Radtke, W.

2004-10-01

318

Assemblies and methods for mitigating effects of reactor pressure vessel expansion  

DOEpatents

Support assemblies for allowing RPV radial expansion while simultaneously limiting horizontal, vertical, and azimuthal movement of the RPV within a nuclear reactor are described. In one embodiment, the support assembly includes a support block and a guide block. The support block includes a first portion and a second portion, and the first portion is rigidly coupled to the RPV adjacent the first portion. The guide block is rigidly coupled to a reactor pressure vessel support structure and includes a channel sized to receive the second portion of the support block. The second portion of the support block is positioned in the guide block channel to movably couple the guide block to the support block.

Challberg, Roy C. (Livermore, CA); Gou, Perng-Fei (Saratoga, CA); Chu, Cherk Lam (San Jose, CA); Oliver, Robert P. (Topsham, ME)

1999-01-01

319

Analysis of the pool critical assembly pressure vessel benchmark using pentran  

SciTech Connect

The internationally circulated Pool Critical Assembly (PCA) Pressure Vessel Benchmark was analyzed using the PENTRAN Parallel Sn code system for the geometry, material, and source specifications as described in the PCA Benchmark documentation. This research focused on utilizing the BUGLE-96 cross section library and accompanying reaction rates, while examining both adaptive differencing on a coarse mesh basis as well as Directional Theta Weighted Sn differencing in order to compare the calculated PENTRAN results to measured data. The results show good comparison with the measured data as well as to the calculated results provided from TORT for the BUGLE-96 cross sections and reaction rates, which suggests PENTRAN is a viable and reliable code system for calculation of light water reactor neutron shielding and dosimetry calculations. (authors)

Edgar, C. A.; Sjoden, G. E. [Nuclear and Radiological Engineering Program, George W. Woodruff School of Mechanical Engineering, Georgia Inst. of Technology, 770 State St, Atlanta, GA 30332-0745 (United States)

2012-07-01

320

Development of a shallow-flaw fracture assessment methodology for nuclear reactor pressure vessels  

SciTech Connect

Shallow-flaw fracture technology is being developed within the Heavy-Section Steel Technology (HSST) Program for application to the safety assessment of radiation-embrittled nuclear reactor pressure vessels (RPVs) containing postulated shallow flaws. Cleavage fracture in shallow-flaw cruciform beam specimens tested under biaxial loading at temperatures in the lower transition temperature range was shown to be strain-controlled. A strain-based dual-parameter fracture toughness correlation was developed and shown to be capable of predicting the effect of crack-tip constraint on fracture toughness for strain-controlled fracture. A probabilistic fracture mechanics (PFM) model that includes both the properties of the inner-surface stainless-steel cladding and a biaxial shallow-flaw fracture toughness correlation gave a reduction in probability of cleavage initiation of more than two orders of magnitude from an ASME-based reference case.

Bass, B.R.; Bryson, J.W.; Dickson, T.L.; McAfee, W.J.; Pennell, W.E.

1996-06-01

321

Kinetics of irradiation-induced Cu precipitation in nuclear reactor pressure vessel steels  

NASA Astrophysics Data System (ADS)

The followup of the embrittlement of nuclear power reactor pressure vessels (RPVs) is of critical importance for the safety assessment in the nuclear industry. The prediction of their future degradation is based on the extrapolation of the past testing of surveillance materials irradiated in the power reactor and in material testing reactors with accelerated dose rates. Using positron annihilation spectroscopy, however, we here reveal a kinetics of irradiation-induced precipitation, i.e., very low dose rate can significantly enhance Cu nanoprecipitation. The mechanism results in the embrittlement in practical RPVs, occurring at a much earlier stage than that found from accelerated tests, suggesting that accelerated tests are not enough for prediction of the embrittlement from Cu nanoprecipitation.

Nagai, Y.; Toyama, T.; Nishiyama, Y.; Suzuki, M.; Tang, Z.; Hasegawa, M.

2005-12-01

322

Characterisation of creep cavitation damage in a stainless steel pressure vessel using small angle neutron scattering  

NASA Astrophysics Data System (ADS)

Grain-boundary cavitation is the dominant failure mode associated with initiation of reheat cracking, which has been widely observed in austenitic stainless steel pressure vessels operating at temperatures within the creep range (>450 °C). Small angle neutron scattering (SANS) experiments at the LLB PAXE instrument (Saclay) and the V12 double-crystal diffractometer of the HMI-BENSC facility (Berlin) are used to characterise cavitation damage (in the size range R=10-2000 nm) in a variety of creep specimens extracted from ex-service plant. Factors that affect the evolution of cavities and the cavity-size distribution are discussed. The results demonstrate that SANS techniques have the potential to quantify the development of creep damage in type-316H stainless steel, and thereby link microstructural damage with ductility-exhaustion models of reheat cracking.

Bouchard, P. J.; Fiori, F.; Treimer, W.

323

Fatigue crack growth behavior of pressure vessel steels and submerged arc weldments in a high-temperature pressurized water environment  

SciTech Connect

The fatigue crack growth rate (FCGR) properties of SA508 Cl 2a and SA533 Gr A Cl 2 pressure vessel steels and the corresponding automatic submerged arc weldments were developed in a high-temperature pressurized water (HPW) environment at 288{degrees} C (550{degrees} F) and 7.2 MPa (1044 psi) at load ratios of 0.20 and 0.50. The properties were generally conservative compared to American Society of Mechanical Engineers Section XI water environment reference curve. The growth rate of fatigue cracks in the base materials, however, was faster in the HPW environment than in a 288{degrees} C (550{degrees} F) base line air environment. The growth rate of fatigue cracks in the two submerged arc weldments was also accelerated in the HPW environment but to a lesser degree than that demonstrated by the base materials. In the air environment, fatigue striations were observed, independent of material and load ratio, while in the HPW environment, some intergranular facets were present. The greater environmental effect on crack growth rates displayed by the base materials compared the weldments attributed to a different sulfide composition and morphology.

Liaw, P.K.; Logsdon, W.A.; Begley, J.A. (Westinghouse Electric Corp., Pittsburgh, PA (USA). Research and Development Center)

1989-10-01

324

Crack inspection of sour and amine service vessels and amine service vessels in hydrocarbon production  

SciTech Connect

This paper reports on crack inspection of sour and amine service vessels in hydrocarbon production. Amoco Production Company initiated an internal inspection program to detect cracking in sour and amine service pressure vessels. Wet fluorescent magnetic particle testing of welds revealed environmental stress cracking in 13 percent of the vessels. However, this sensitive technique also detected manufacturing-related cracking and/or defects in an additional 35 percent of the vessels.

Miller, C.F. (Amoco Production Co., Houston, TX (United States)); Sperling, E.J. (Amoco Oil Co., Naperville, IL (United States). Research and Development Dept.)

1992-07-01

325

Effects of Hyperbaric Pressure on a Deep-Sea Archaebacterium in Stainless Steel and Glass-Lined Vessels  

PubMed Central

The effects of hyperbaric helium pressures on the growth and metabolism of the deep-sea isolate ES4 were investigated. In a stainless steel reactor, cell growth was completely inhibited but metabolic gas production was observed. From 85 to 100°C, CO2 production proceeded two to three times faster at 500 atm (1 atm = 101.29 kPa) than at 8 atm. At 105°C, no CO2 was produced until the pressure was increased to 500 atm. Hydrogen and H2S were also produced biotically but were not quantifiable at pressures above 8 atm because of the high concentration of helium. In a glass-lined vessel, growth occurred but the growth rate was not accelerated by pressure. In most cases at temperatures below 100°C, the growth rate was lower at elevated pressures; at 100°C, the growth rates at 8, 250, and 500 atm were nearly identical. Unlike in the stainless steel vessel, CO2 production was exponential during growth and continued for only a short time after growth. In addition, relatively little H2 was produced in the glass-lined vessel, and there was no growth or gas production at 105°C at any pressure. The behavior of ES4 as a function of temperature and pressure was thus very sensitive to the experimental conditions.

Nelson, Chad M.; Schuppenhauer, Michael R.; Clark, Douglas S.

1991-01-01

326

Solid State Track Recorder fission rate measurements in low power light water reactor pressure vessel mockups  

SciTech Connect

The results of extensive SSTR measurements made at the Pool Critical Assembly (PCA) facility at Oak Ridge National Laboratory have been reported previously. Measurements were made at key locations in PCA which is an idealized mockup of the water gap, thermal shield, pressure vessel geometry of a light water reactor. Recently, additional SSTR fission rate measurements have been carried out for 237-Np, 238-U, and 235-U in key locations in the NESTOR Shielding and Dosimetry Improvement Program (NESDIP) mockup facility located at Winfrith, England. NESDIP is a replica of the PCA facility, and comparisons will be made between PCA and NESDIP measurements. The results of measurements made at the engineering mockup at the VENUS critical assembly at CEN/SCK, Mol, Belgium will also be reported. Measurements were made at selected radial and azimuthal locations in VENUS, which models the in-core and near-core regions of a pressurized water reactor. Comparisons of absolute SSTR fission rates with absolute fission rates made with the Mol miniature fission chamber will be reported. Absolute fission rate comparisons have also been made between the NBS fission chamber, radiometric fission foils, and SSTRs, and these results will be summarized.

Ruddy, F.H.; Roberts, J.H.; Kellogg, L.S.; Gold, R.; Lippincott, E.P.; Preston, C.C.; Leenders, L.; Fabry, A.; McGarry, E.D.; Murphy, M.F.

1985-06-14

327

Embedded fiber optic sensor arrays for structural health monitoring of filament wound composite pressure vessels  

NASA Astrophysics Data System (ADS)

Optical Fiber Bragg Grating (FBG) strain and temperature sensors were embedded into four carbon/epoxy, filament-wound 5.75' diameter Standard Testing and Evaluation Bottles (STEBs). These sensors were used to monitor temperature and strain during cure and pressurization of the pressure vessels. Preliminary to this work, micrographs were made of embedded fiber, showing good incorporation of the fiber into the material and no degradation of the optical fiber's acrylate coating. A survey was also made of different ingress/egress techniques to protecting the fiber as in enters the bottle and preventing attenuation and power fluctuation, with Tefzel tubing proving to be the most effective method. The FBGs were embedded parallel to the reinforcing fibers, in the hoop and helical directions, and also in the axial direction. The sensors showed close agreement with surface-mounted Resistance Strain Gages (RSGs),as well as finite element modeling. Sensors in the hoop direction embedded at mid-cylinder showed the closest agreement (-1.2%), while agreement for hoop- direction sensors embedded near the ends of the bottle (11%) was not as close. The agreement was also better for helically directed sensors embedded at mid-cylinder (-1.6%?) than for those embedded near the ends (-24%). Some preliminary impact testing was conducted that indicated FBG sensors would be appropriate for sensing impact damage.

Foedinger, Richard C.; Rea, David L.; Sirkis, James S.; Baldwin, Christopher S.; Troll, John R.; Grande, Robert; Davis, Craig S.; Vandiver, Terry L.

1999-05-01

328

A perspective on thermal annealing of reactor pressure vessel materials from the viewpoint of experimental results  

SciTech Connect

It is believed that in the next decade or so, several nuclear reactor pressure vessels (RPVs) may exceed the reference temperature limits set by the pressurized thermal shock screening criteria. One of the options to mitigate the effects of irradiation on RPVs is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. This paper summarizes recent experimental results from work performed at the Oak Ridge National Laboratory to study the annealing response, or ``recovery`` of several irradiated RPV steels. The fracture toughness is one of the important properties used in the evaluation of the integrity of RPVs. Optimally, the fracture toughness is measured directly by fracture toughness specimens, such as compact tension or precracked Charpy specimens, but is often inferred from the results of Charpy V-notch impact specimens. The experimental results are compared to the predictions of models for embrittlement recovery which have been developed by Eason et al. Some of the issues in annealing that still need to be resolved are discussed.

Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K.

1996-04-01

329

Thermal-Hydraulic Analyses of Pressurized-Thermal-Shock-Induced Vessel Ruptures.  

National Technical Information Service (NTIS)

A severe overcooling transient was postulated to produce vessel wall temperatures below the nil-ductility transition temperature which in conjunction with system repressurization, led to vessel rupture at the core midplane. Such transients are referred to...

D. Dobranich

1982-01-01

330

The use of excised, pressurized blood vessels to study the physiology of vascular smooth muscle  

Microsoft Academic Search

constriction. Such a mechanism may need to operate with some precision as blood flow is a high power function of the internal radius of a blood vessel. Precise control may be particularly important for those vessels which play a major role in regulating the peripheral resistance or have the capacity to do so. Folkow ~~ believes that the arterial vessels

R. N. Speden

1985-01-01

331

Dome Shape Optimization of Composite Pressure Vessels Based on Rational B-Spline Curve and Genetic Algorithm  

NASA Astrophysics Data System (ADS)

This paper presents an algorithm for shape optimization of composite pressure vessels head. The shape factor which is defined as the ratio of internal volume to weight of the vessel is used as an objective function. Design constrains consist of the geometrical limitations, winding conditions, and Tsai-Wu failure criterion. The geometry of dome shape is defined by a B-spline rational curve. By altering the weights of control points, depth of dome, and winding angle, the dome shape is changed. The proposed algorithm uses genetic algorithm and finite element analysis to optimize the design parameters. The algorithm is applied on a CNG pressure vessel and the results show that the proposed algorithm can efficiently define the optimal dome shape. This algorithm is general and can be used for general shape optimization.

Vafaeesefat, Abbas

2009-10-01

332

Neutron spectra at different High Flux Isotope Reactor (HFIR) pressure vessel surveillance locations  

SciTech Connect

This project addresses the potential problem of radiation embrittlement of reactor pressure vessel (RPV) supports. Surveillance specimens irradiated at the High Flux Isotope Reactor (HFIR) at relatively low neutron flux levels (about 1.5E + 8 cm{sup {minus}2}.s{sup {minus}1}) and low temperatures (about 50{degrees}C) showed embrittlement more rapidly than expected. Commercial power reactors have similar flux levels and temperatures at the level vessel support structures. The purposes of this work are to provide the neutron fluence spectra data that are needed to evaluate previously measured mechanical property changes in the HFIR, to explain the discrepancies in neutron flux levels between the nickel dosimeters and two other dosimeters, neptunium and beryllium, and to address any questions or peculiarities of the HFIR reactor environment. The current work consists of neutron and gamma transport calculations, dosimetry measurements, and least-squares logarithmic adjustment to obtain the best estimates for the neutron spectra and the related neutron exposure parameters. The results indicate that the fission rates in neptunium-237 (Np-237) and uranium-238 (U-238) and the helium production rates in beryllium-9 (Be-9) are dominated by photo-induced reactions. The displacements per atom rate for iron (dpa/s) from gamma rays is five times higher than the dpa/s from neutrons. The neutron fluxes in key 7, position 5 do not show any significant gradient in the surveillance capsule, but key 4 and key 2 showed differences in magnitude as well as in the shape of the spectrum. The stainless steel monitor in the V-notch of the Charpy specimens of the surveillance capsules is adequate to determine the neutron flux above 1.0 MeV at the desired V-notch location. Simultaneous adjustment of neutron and gamma fluxes with the measurements has been demonstrated and should avoid future problems with photo-induced reactions.

Remec, I. [Josef Sefan Inst., Ljubljana (Slovenia); Kam, F.B. [Oak Ridge National Lab., TN (United States)

1993-12-01

333

Survey of Welding Processes for Field Fabrication of 2 1/4 Cr-1 Mo Steel Pressure Vessels.  

National Technical Information Service (NTIS)

Any evaluation of fabrication methods for massive pressure vessels must consider several welding processes with potential for heavy-section applications. These include submerged-arc and shielded metal-arc, narrow-joint modifications of inert-gas metal-arc...

G. E. Grotke

1980-01-01

334

Influences of welding processes on fatigue life of cruciform joints of pressure vessel grade steels containing LOP defects  

Microsoft Academic Search

The influences of two welding processes, namely, shielded metal arc welding (SMAW) and flux cored arc welding (FCAW), on fatigue life of cruciform joints, containing lack of penetration (LOP) defects, have been studied. Load carrying cruciform joints were fabricated from high strength, quenched and tempered steels of pressure vessel (ASTM 517 ‘F’) grade. Fatigue crack growth experiments were carried out

V Balasubramanian; B Guha

2000-01-01

335

Establishing criteria for root and toe cracking of load carrying cruciform joints of pressure vessel grade steel  

Microsoft Academic Search

In this investigation an attempt has been made to establish a criterion to forecast the possible crack initiation region (toe or root) in double fillet welded load carrying cruciform joints and also to know the probable failure mode. Cruciform joints were fabricated from pressure vessel grade (ASTM 517 ‘F’ grade) steel using shielded metal arc welding (SMAW) and flux cored

V. Balasubramanian; B. Guha

2004-01-01

336

Fatigue Crack Propagation and Fracture Studies of a Pressure Vessel Steel Temper Embrittled to Simulate Irradiation Damage.  

National Technical Information Service (NTIS)

Fatigue crack propagation tests were conducted using plate bend specimens machined from shell material of the PM-2A half-scale model pressure vessel. The material is a Cr-Mo-V rotor steel, temper embrittled to represent the irradiated shell of the PM-2A r...

T. W. Crooker L. A. Cooley E. A. Lange

1967-01-01

337

A new series of advanced 3Cr-Mo-Ni steels for thick section pressure vessels in high temperature and pressure hydrogen service  

Microsoft Academic Search

A new series of 3Cr-Mo-Ni steels has been developed for use in thick section pressure vessels, specifically for coal conversion\\u000a (high temperature and high pressure hydrogen) service. The new steels rely on minor alloy modifications to commercial 2.25Cr-1Mo\\u000a (ASTM A387 Grade 22 Class 2) steel. Based on evaluations in relatively small heats (55 kg), the experimental alloys, which\\u000a employ additions

R. O. Ritchie; E. R. Parker; P. N. Spencer; J. A. Todd

1984-01-01

338

Characterization of Quench-Extracted High Pressure Stressed Microorganisms  

NASA Astrophysics Data System (ADS)

In-situ high pressure microbiology work by Sharma et al (2002) presented a unique approach with diamond anvil cells to the study of microbes under environmental stress. This study focused on high pressure exposure as the stress component and provided a technique to directly monitor microbial activity. However, it lacked the much desired biochemical and biophysical information that could reflect the state of surviving microorganisms with insights into the process of adaptation at extreme. More recent work (Sharma et al 2011) expands on the previous study by including synergistic effect of high temperature with increased pressures along variable time scale. With the cell extraction and subsequent cell growth demonstrated, Sharma et al. (2011) show that more than pressure, temperature remains the environmental variable that defines the limits of life's survival. In this study we have refined the extraction process from the diamond anvil cell such that the stressed microorganisms can be routinely available for in-depth physiological study using conventional and state-of-the-art high resolution imaging tools. Here we present some recent in-depth FESEM, AFM and optical spectroscopy data to study the effect of stress on Escherichia coli. Contrary to earlier studies where various cell membrane ruptures were reported after moderate pressure exposure, we find that most cells remain viable and except for some occasional anomalous morphology, the surviving cells were similar to the unstressed state. Preliminary results suggest that the stress response in Escherichia coli exposed to short term extreme pressures (ranging from 1 -24 hrs) seems rapidly reversible. Biophysical entities such as the cell membrane, therefore, remain intact in the whole organism (and colony of microorganisms) at significantly higher pressure conditions than 300 MPa as reported in previous biophysics literature.

Sharma, P.; Sharma, A.

2011-12-01

339

Balancing food and predator pressure induces chronic stress in songbirds.  

PubMed Central

The never-ending tension between finding food and avoiding predators may be the most universal natural stressor wild animals experience. The 'chronic stress' hypothesis predicts: (i) an animal's stress profile will be a simultaneous function of food and predator pressures given the aforesaid tension; and (ii) these inseparable effects on physiology will produce inseparable effects on demography because of the resulting adverse health effects. This hypothesis was originally proposed to explain synergistic (inseparable) food and predator effects on demography in snowshoe hares (Lepus americanus). We conducted a 2 x 2, manipulative food addition plus natural predator reduction experiment on song sparrows (Melospiza melodia) that was, to our knowledge, the first to demonstrate comparable synergistic effects in a bird: added food and lower predator pressure in combination produced an increase in annual reproductive success almost double that expected from an additive model. Here we report the predicted simultaneous food and predator effects on measures of chronic stress in the context of the same experiment: birds at unfed, high predator pressure (HPP) sites had the highest stress levels; those at either unfed or HPP sites showed intermediate levels; and fed birds at low predator pressure sites had the lowest stress levels.

Clinchy, Michael; Zanette, Liana; Boonstra, Rudy; Wingfield, John C; Smith, James N M

2004-01-01

340

Thermal Analysis to Calculate the Vessel Temperature and Stress in Alcator C-Mod Due to the Divertor Upgrade  

SciTech Connect

Alcator C-Mod is planning an upgrade to its outer divertor. The upgrade is intended to correct the existing outer divertor alignment with the plasma, and to operate at elevated temperatures. Higher temperature operation will allow study of edge physics behavior at reactor relevant temperatures. The outer divertor and tiles will be capable of operating at 600oC. Longer pulse length, together with the plasma and RF heat of 9MW, and the inclusion of heater elements within the outer divertor produces radiative energy which makes the sustained operation much more difficult than before. An ANSYS model based on ref. 1 was built for the global thermal analysis of C-Mod. It models the radiative surfaces inside the vessel and between the components, and also includes plasma energy deposition. Different geometries have been simulated and compared. Results show that steady state operation with the divertor at 600oC is possible with no damage to major vessel internal components. The differential temperature between inner divertor structure, or "girdle" and inner vessel wall is ~70oC. This differential temperature is limited by the capacity of the studs that hold the inner divertor backing plates to the vessel wall. At a 70oC temperature differential the stress on the studs is within allowable limits. The thermal model was then used for a stress pass to quantify vessel shell stresses where thermal gradients are significant.

Han Zhang, Peter H. Titus, Robert Ellis, Soren Harrison and Rui Vieira

2012-08-29

341

Calculation of Mechanical Strength of the Bolts of the Flanged Joints of LWR-Type Reactor Pressure Vessels (With Particular Emphasis on the Behaviour under Critical Internal Excess Pressure, Acting Like a ''Safety Valve''). 5. Technical Report.  

National Technical Information Service (NTIS)

The reactor pressure vessel has to be made absolutely fail-safe towards excess primary loads (internal pressure). For this purpose, the vessel is equipped with safety valves (e.g. at the pressurizer) which normally are fully sufficient to master any press...

K. H. Herter

1984-01-01

342

Life management of reactor pressure vessels under pressurized thermal shock loading: deterministic procedure and application to Western and Eastern type of reactors  

Microsoft Academic Search

The integrity of the reactor pressure vessel (RPV) has to be maintained throughout the plant life and it is also one of the main considerations regarding the plant life extension. Adequate approaches to the RPV integrity assessment provides a basis for plant-safe operation and for timely implementation of preventive and corrective measures if necessary. A substantial part of the RPV

Elisabeth Keim; Cornelia Schmidt; Albert Schöpper; Roland Hertlein

2001-01-01

343

A Review of Fatigue Crack Growth of Pressure Vessel and Piping Steels in High-Temperature, Pressurized Reactor-Grade Water.  

National Technical Information Service (NTIS)

Fatigue crack growth data sets, for pressure vessel and piping steels, in reactor-grade water environment have appeared in various reports and publications since about 1972. All of the results which have been published from 1972 through 1979 have been plo...

W. H. Cullen K. Torronen

1980-01-01

344

A review of fatigue crack growth of pressure vessel and piping steels in high-temperature, pressurized reactor-grade water. Interim report  

Microsoft Academic Search

Fatigue crack growth data sets, for pressure vessel and piping steels, in reactor-grade water environment have appeared in various reports and publications since about 1972. All of the results which have been published from 1972 through 1979 have been plotted and are presented in this report. Beginning with a discussion of the need for these data, and an explanation of

W. H. Cullen; K. Torronen

1980-01-01

345

A review of fatigue crack growth of pressure vessel and piping steels in high-temperature, pressurized reactor-grade water. Memorandum report  

Microsoft Academic Search

Fatigue crack growth data sets, for pressure vessel and piping steels, in reactor-grade water environment have appeared in various reports and publications since about 1972. All of the results which have been published from 1972 through 1979 have been plotted and are presented in this report. Beginning with a discussion of the need for these data, and an explanation of

W. H. Cullen; K. Torronen

1980-01-01

346

Effects of 50/degree/C surveillance and test reactor irradiations on ferritic pressure vessel steel embrittlement  

SciTech Connect

The results of surveillance tests on the High-Flux Isotope Reactor (HFIR) pressure vessel at the Oak Ridge National Laboratory revealed that a greater than expected embrittlement had taken place after about 17.5 effective full-power years of operation and an operational assessment program was undertaken to fully evaluate the vessel condition and recommend conditions under which operation could be resumed. A research program was undertaken that included irradiating specimens in the Oak Ridge Research Reactor. Specimens of the A212 grade B vessel shell material were included, along with specimens from a nozzle qualification weld and a submerged-arc weld fabricated at ORNL to reproduce the vessel seam weld. The results of the surveillance program and the materials research program performed in support of the evaluation of the HFIR pressure vessel are presented and show the welds to be more radiation resistant than the A212B. Results of irradiated tensile and annealing experiments are described as well as a discussion of mechanisms which may be responsible for enhanced hardening at low damage rates. 20 refs., 22 figs., 5 tabs.

Nanstad, R.K.; Iskander, S.K.; Rowcliffe, A.F.; Corwin, W.R.; Odette, G.R.

1988-01-01

347

Results of examinations of pressure vessel samples and instrument nozzles from the TMI-2 lower head  

SciTech Connect

Fifteen prism-shaped steel samples were removed from the lower head of the damaged TMI-2 reactor pressure vessel to assess the effects of approximately 19 metric tons of molten core debris that had relocated there during the 1979 loss-of-coolant accident. Metallographic examinations of the samples revealed that inside surface temperatures of 800 to 1,100{degree}C were attained during the accident in an elliptical shaped ``hot spot`` {approx}1 {times} 0.7 m. Tensile, creep, and Charpy V-notch specimens were also cut from the samples to assess the mechanical properties of the lower head material at temperatures up to the peak accident temperature. These properties were used in a margin to failure analysis of the lower head. Examinations of instrument nozzles removed from the lower head region assisted in defining the relocation scenario of the molten core debris and showed that the lower head was largely protected from catastrophic failure by a solidified layer around the molten core debris that acted as a partial thermal insulator.

Korth, G.E. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Diercks, D.R.; Neimark, L.A. [Argonne National Lab., IL (United States)

1993-10-01

348

Methods for incorporating the effects of LWR coolant environments in pressure vessel and piping fatigue evaluations.  

SciTech Connect

This paper summarizes the work performed at Argonne National Laboratory on the fatigue of piping and pressure vessel steels in the coolant environments of light water reactors. The existing fatigue strain vs. life ({var_epsilon}-N) data were evaluated to establish the effects of various material and loading variables, such as steel type, strain range, strain rate, temperature, and dissolved-oxygen level in water, on the fatigue lives of these steels. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for carbon and low-alloy steels and austenitic stainless steels as a function of material, loading, and environment variables. Case studies of fatigue failures in nuclear power plants are presented, and the contribution of environmental effects to crack initiation is discussed. Methods for incorporating environmental effects into the ASME Code fatigue evaluations are discussed. Data available in the literature have been reviewed to evaluate the possible conservatism in the existing fatigue design curves of the ASME Code.

Chopra, O. K.; Shack, W. J.

2002-07-31

349

The role of point defect clusters in reactor pressure vessel embrittlement  

SciTech Connect

Radiation-induced point defect clusters (PDC) are a plausible source of matrix hardening in reactor pressure vessel (RPV) steels in addition to copper-rich precipitates. These PDCs can be of either interstitial or vacancy type, and could exist in either 2 or 3-D shapes, e.g. small loops, voids, or stacking fault tetrahedra. Formation and evolution of PDCs are primarily determined by displacement damage rate and irradiation temperature. There is experimental evidence that size distributions of these clusters are also influenced by impurities such as copper. A theoretical model has been developed to investigate potential role of PDCs in RPV embrittlement. The model includes a detailed description of interstitial cluster population; vacancy clusters are treated in a more approximate fashion. The model has been used to examine a broad range of irradiation and material parameters. Results indicate that magnitude of hardening increment due to these clusters can be comparable to that attributed to copper precipitates. Both interstitial and vacancy type defects contribute to this hardening, with their relative importance determined by the specific irradiation conditions.

Stoller, R.E.

1993-10-01

350

Metallographic and hardness examinations of TMI-2 lower pressure vessel head samples  

SciTech Connect

Fifteen steel samples were removed from the lower pressure vessel head of the damaged TMI-2 nuclear reactor to assess the thermal threat to the head posed by 15 to 20 metric tons of molten core debris relocating there during the accident. Full sections of thirteen of the samples and partial sections of the other two samples underwent hardness and metallographic examinations at the Idaho National Engineering Laboratory. These examinations have shown that eleven of the fifteen samples did not exceed the ferrite-austenite transformation temperature of 727 C during the accident. The remaining four samples did show evidence of having a much more severe thermal history. The samples from core grid positions F-10 and G-8 are believed to have experienced temperatures of 1,040 to 1,060 C for about 30 minutes. Samples from positions E-8 and E-6 appear to have been subjected to 1,075 to 1,100 C for approximately 30 minutes.

Korth, G. E. [EG and G Idaho, Inc., Idaho Falls, ID (United States)

1994-03-01

351

The impact of mobile point defect clusters in a kinetic model of pressure vessel embrittlement  

SciTech Connect

The results of recent molecular dynamics simulations of displacement cascades in iron indicate that small interstitial clusters may have a very low activation energy for migration, and that their migration is 1-dimensional, rather than 3-dimensional. The mobility of these clusters can have a significant impact on the predictions of radiation damage models, particularly at the relatively low temperatures typical of commercial, light water reactor pressure vessels (RPV) and other out-of-core components. A previously-developed kinetic model used to investigate RPV embrittlement has been modified to permit an evaluation of the mobile interstitial clusters. Sink strengths appropriate to both 1- and 3-dimensional motion of the clusters were evaluated. High cluster mobility leads to a reduction in the amount of predicted embrittlement due to interstitial clusters since they are lost to sinks rather than building up in the microstructure. The sensitivity of the predictions to displacement rate also increases. The magnitude of this effect is somewhat reduced if the migration is 1-dimensional since the corresponding sink strengths are lower than those for 3-dimensional diffusion. The cluster mobility can also affect the evolution of copper-rich precipitates in the model since the radiation-enhanced diffusion coefficient increases due to the lower interstitial cluster sink strength. The overall impact of the modifications to the model is discussed in terms of the major irradiation variables and material parameter uncertainties.

Stoller, R.E.

1998-05-01

352

Nondestructive Magnetic Adaptive Testing of nuclear reactor pressure vessel steel degradation  

NASA Astrophysics Data System (ADS)

Inspection of neutron-irradiation-generated degradation of nuclear reactor pressure vessel steel (RPVS) is a very important task. In ferromagnetic materials, such as RPVS, the structural degradation is connected with a change of their magnetic properties. In this work, applicability of a novel magnetic nondestructive method (Magnetic Adaptive Testing, MAT), based on systematic measurement and evaluation of minor magnetic hysteresis loops, is shown for inspection of neutron irradiation embrittlement in RPVS. Three series of samples, made of JRQ, 15CH2MFA and 10ChMFT type steels were measured by MAT. The samples were irradiated by E > 1 MeV energy neutrons with total neutron fluence of 1.58 × 1019-11.9 × 1019 n/cm2. Regular correlation was found between the optimally chosen MAT degradation functions and the neutron fluence in all three types of the materials. Shift of the ductile-brittle transition temperature, ?DBTT, independently determined as a function of the neutron fluence for the 15CH2MFA material, was also evaluated. A sensitive, linear correlation was found between the ?DBTT and values of the relevant MAT degradation function. Based on these results, MAT is shown to be a promising (at least) complimentary tool of the destructive tests within the surveillance programs, which are presently used for inspection of neutron-irradiation-generated embrittlement of RPVS.

Tomáš, I.; Vértesy, G.; Gillemot, F.; Székely, R.

2013-01-01

353

Study, Examinations, and Stress: Blood Pressure Assessments in College Students  

ERIC Educational Resources Information Center

The issue of stress associated with higher education and its impact on markers of student health is explored in three experiments looking at blood pressure levels in college students. All participants were full-time undergraduate students of psychology. In Experiment 1, academic fear of failure, assessed using psychometric testing, was found to be…

Hughes, Brian M.

2005-01-01

354

Study, Examinations, and Stress: Blood Pressure Assessments in College Students  

ERIC Educational Resources Information Center

|The issue of stress associated with higher education and its impact on markers of student health is explored in three experiments looking at blood pressure levels in college students. All participants were full-time undergraduate students of psychology. In Experiment 1, academic fear of failure, assessed using psychometric testing, was found to…

Hughes, Brian M.

2005-01-01

355

Grain boundary cavity growth under applied stress and internal pressure  

SciTech Connect

The growth of grain boundary cavities under applied stress and internal gas pressure was investigated. Methane gas filled cavities were produced by the C + 4H reversible CH4 reaction in the grain boundaries of type 270 nickel by hydrogen charging in an autoclave at 500/sup 0/C with a hydrogen pressure of either 3.4 or 14.5 MPa. Intergranular fracture of nickel was achieved at a charging temperature of 300/sup 0/C and 10.3 MPa hydrogen pressure. Cavities on the grain boundaries were observed in the scanning electron microscope after fracture. Photomicrographs of the cavities were produced in stereo pairs which were analyzed so as to correct for perspective distortion and also to determine the orientational dependence of cavity growth under an applied tensile stress.

Mancuso, J.F.

1977-08-01

356

D0 Silicon Upgrade: Gas Helium Storage Tank Pressure Vessel Engineering Note  

SciTech Connect

This is to certify that Beaird Industries, Inc. has done a white metal blast per SSPC-SP5 as required per specifications on the vessel internal. Following the blast, a black light inspection was performed by Beaird Quality Control personnel to assure that all debris, grease, etc. was removed and interior was clean prior to closing vessel for helium test.

Rucinski, Russ; /Fermilab

1996-11-11

357

On the character of nanoscale features in reactor pressure vessel steels under neutron irradiation  

NASA Astrophysics Data System (ADS)

Nanostructural features that form in reactor pressure vessel steels under neutron irradiation at around 290°C are responsible for significant hardening and embrittlement. It is well established that the nanostructural features can be separated into well formed precipitates and matrix features comprised of point defect clusters complexed with solutes, which may also include regions of solute enrichment that are not well formed precipitates. However, a more detailed atomicscale understanding of these features is needed to better interpret experimental measurements and provide a physical basis for predictive embrittlement models. The overall objective of this work is to provide atomic-level insight into the character of the nanostructural features and the physical processes involved in their formation. One focus of this work has been on modeling cascade aging; defined as the evolution of self-interstitial and vacancy defects spanning from their spatially correlated birth in displacement cascades over picoseconds to times on the order of >10 5 seconds, when defect populations have built up to steady-state values and no longer have a geometric correlation. During cascade aging, the self-interstitial and vacancy fluxes are responsible for radiation enhanced diffusion, resulting in wellformed precipitates, and are a direct source of matrix defect features. Many-bodied molecular-statics energy relaxation methods have been used to investigate the structure and energetics of self-interstitial and vacancy clusters. The characterization reveals that self-interstitial clusters form as highly kinked, prismatic, perfect proto dislocation loops and vacancy clusters form as faceted three-dimensional clusters. Molecular dynamics simulations of self-interstitial cluster migration reveal that they undergo easy one-dimensional glide, probably due to the presence and easy motion of intrinsic kinks. Our study of the structural characteristics and mobility of the self-interstitial clusters leads to the conclusion of limited vacancy-interstitial recombination during cascade aging. Kinetic Lattice Monte Carlo (KLMC) simulations have been used to provide insight into the coupled vacancy and solute clustering during cascade aging. The simulations reveal that cascade vacancy-solute clustering may play a role in the formation of dilute atmospheres of solute enrichment and serve to enhance the formation of manganese-nickel rich precipitates at low copper levels. KLMC simulations have also been used to study copper diffusion and precipitation in dilute Fe-Cu alloys and reveal that highly correlated copper cluster migration mechanisms occur in these steels. The primary result is that larger clusters, with 5-30 vacancies, form in cascades with thermal lifetimes up to 7.1x105s . The nanostructural features have been experimentally characterized using small angle neutron scattering (SANS). This work describes the comprehensive single variable experimental studies which characterize the evolution of copper and/or manganese nickel rich precipitates (CRP and/or MNP) as a function of key embrittlement variables. Post-irradiation annealing is a method of ameliorating irradiation embrittlement in these steels, and a set of SANS experiments have been performed which characterize the precipitate evolution during post-irradiation annealing (PIA) at 400 and 450°C . The character of matrix defect features cannot be obtained from SANS experiments alone, but have been studied in irradiated low copper steels which do not contain well-formed precipitates. In summary, this work has provided a semi-quantitative analysis of cascade aging in reactor pressure vessel steels under neutron irradiation, with an emphasis on the character of the nano-scale features.

Wirth, Brian David

358

Stress intensity factors for an underclad nozzle corner crack subjected to pressure and thermal loading  

SciTech Connect

The opening mode linear elastic stress intensity factor, K{sub I}, was computed, via 3-D elastic finite element techniques, for an embedded elliptical crack located just beneath the cladding at the nozzle corner in a pressure vessel. Pressure loading and several thermal transient loading conditions were analyzed. The underclad crack was explicitly modeled and K{sub I} was computed explicitly, from the energy release rate, J. The variation of the maximum principal stress along the minor axis of the elliptical crack was determined for a companion set of thermal/structural analyses that were performed in the absence of the crack. These stress distributions were linearized into equivalent membrane and bending stress components that were used to compute K{sub I} from the Shah and Kobayashi solutions for near-surface embedded elliptical cracks. The explicitly computed K{sub I} values were found to be in very good agreement with the K{sub I} values computed from the flat plate'' solutions of Reference 1, for all the loading cases analyzed. An additional comparison was made between the energy release rate results and the results obtained by fitting the 1/{radical}r stress singularity to the crack tip stress field at the Gaussian integration points nearest to the crack front. The observed excellent agreement between the two independent explicit'' computational methods served to verify each of the methods and also demonstrated the adequacy of the refinement of the finite element mesh. These observations support the use of the Shah and Kobayashi flat plate K{sub I} solutions for analyzing underclad cracks at the nozzle corner. 7 refs., 11 figs.

Wilkening, W.W.

1991-06-01

359

Relation of Blood Pressure to Retinal Vessel Diameter in Type 1 Diabetes Mellitus  

PubMed Central

Objective To examine the relationship of blood pressure (BP) and use of angiotensin receptor blocker (ARB) or angiotensin converting enzyme inhibitor (ACEI) to retinal vessel diameter in normotensive, normoalbuminuric persons with type 1 diabetes mellitus (T1DM). Design Randomized controlled clinical trial. Participants Persons with T1DM and gradable fundus photographs both at baseline (n=147) and 5-year follow-up (n=124). Methods Clinic and 24-hour ambulatory BPs (ABP) were measured. Retinal arteriolar and venular diameters were measured using a computer-assisted technique. Individual arteriolar and venular measurements were combined into summary indices that reflect the average retinal arteriolar (central retinal arteriolar equivalent [CRAE]) and venular (central retinal venular equivalent [CRVE]) diameter of an eye, respectively. Main Outcome Measures CRAE and CRVE. Results While controlling for age, study site, glycosylated hemoglobin and ambulatory pulse rate, daytime ambulatory systolic (-0.29 ?m effect per 1mmHg, P=.02) and daytime ambulatory diastolic (-0.44 ?m effect per 1mmHg, P=.04), nighttime ambulatory systolic (-0.27 ?m effect per 1mmHg, P=.03), and 24-hour ambulatory systolic BP (-0.31 ?m effect per 1mmHg, P=.03) were cross-sectionally associated with a smaller CRAE. While controlling for age, study site, glycosylated hemoglobin, ambulatory pulse rate and baseline CRAE, no BP measure was associated with a change in CRAE or CRVE over 5 years of follow-up. Treatment with losartan or enalapril was not associated with a statistically significant change in CRAE or CRVE. Conclusions ACEI or ARB therapy does not affect retinal arteriolar or venular diameter in normotensive persons with T1DM.

Klein, Ronald; Myers, Chelsea E.; Klein, Barbara E. K.; Zinman, Bernard; Gardiner, Robert; Suissa, Samy; Sinaiko, Alan R.; Donnelly, Sandra M.; Goodyer, Paul; Strand, Trudy; Mauer, Michael

2009-01-01

360

An investigation of temperature measurement methods in nuclear power plant reactor pressure vessel annealing  

SciTech Connect

The objective of this project was to provide an assessment of several methods by which the temperature of a commercial nuclear power plant reactor pressure vessel (RPV) could be measured during an annealing process. This project was a coordinated effort between DOE`s Office of Nuclear Energy, Science and Technology; DOE`s Light Water Reactor Technology Center at Sandia National Laboratories; and the Electric Power Research Institute`s Non- Destructive Evaluation Center. Ball- thermocouple probes similar to those described in NUREG/CR-5760, spring-loaded, metal- sheathed thermocouple probes, and 1778 air- suspended thermocouples were investigated in experiments that heated a section of an RPV wall to simulate a thermal annealing treatment. A parametric study of ball material, emissivity, thermal conductivity, and thermocouple function locations was conducted. Also investigated was a sheathed thermocouple failure mode known as shunting (electrical breakdown of insulation separating the thermocouple wires). Large errors were found between the temperature as measured by the probes and the true RPV wall temperature during heat-up and cool-down. At the annealing soak temperature, in this case 454{degrees}C [850`F], all sensors measured the same temperature within about {plus_minus}5% (23.6{degrees}C [42.5{degrees}F]). Because of these errors, actual RPV wall heating and cooling rates differed from those prescribed (by up to 29%). Shunting does not appear to be a problem under these conditions. The large temperature measurement errors led to the development of a thermal model that predicts the RPV wall temperature from the temperature of a ball- probe. Comparisons between the model and the experimental data for ball-probes indicate that the model could be a useful tool in predicting the actual RPV temperature based on the indicated ball- probe temperature. The model does not predict the temperature as well for the spring-loaded and air suspended probes.

Acton, R.U.; Gill, W.; Sais, D.J.; Schulze, D.H.; Nakos, J.T. [Sandia National Labs., Albuquerque, NM (United States)

1996-05-01

361

An analysis of dynamic crack propagation and arrest in a nuclear pressure vessel under thermal shock conditions  

Microsoft Academic Search

The inner wall of a nuclear pressure vessel can become embrittled during service due to irradiation effects. As a result, a small flaw could become critical during the thermal shock that would accompany a loss-of-coolant-accident. To assess the consequences of this possibility, elastodynamic computations were performed on the subsequent rapid unstable crack run-arrest events. One difficulty is the lack of

J. Jung; M. F. Kanninen

1983-01-01

362

An analysis of dynamic crack propagation and arrest in a nuclear pressure vessel under thermal shock conditions  

Microsoft Academic Search

The inner wall of a nuclear pressure vessel can become embrittled during service due to irradiation effects. As a result, a small flaw could become critical during the thermal shock that would accompany a loss-of-coolant-accident. To assess the consequences of this possibility, elastodynamic computations were performed on the subsequent rapid unstable crack run-arrest events. One difficulty is the lack of

J. Jung; M. F. Kanninen

1982-01-01

363

Marine transportation and burial of the Shippingport Reactor Pressure Vessel/Neutron Shield Tank (RPV/NST) package  

SciTech Connect

The Shippingport Station Decommissioning Project (SSDP) is a Department of Energy (DOE) project to dismantle the Shippingport Atomic Power Station. One of the more significant and challenging technical aspects of the project, which is being managed for DOE by GE-Nuclear Energy, is the marine transport of the Reactor Pressure Vessel (RPV) and its associated Neutron Shield Tank (NST) to the government owned Hanford Reservation near Richland, WA. 2 refs.

Coughlin, P.J.

1989-01-01

364

The cryogenic bonding evaluation at the metallic-composite interface of a composite overwrapped pressure vessel with additional impact investigation  

Microsoft Academic Search

A bonding evaluation that investigated the cryogenic tensile strength of several different adhesives\\/resins was performed. The test materials consisted of 606 aluminum test pieces adhered to a wet-wound graphite laminate in order to simulate the bond created at the liner-composite interface of an aluminum-lined composite overwrapped pressure vessel. It was found that for cryogenic applications, a flexible, low modulus resin

Eric A. Clark

2010-01-01

365

Prediction of failure pressure and leak rate of stress corrosion.  

SciTech Connect

An ''equivalent rectangular crack'' approach was employed to predict rupture pressures and leak rates through laboratory generated stress corrosion cracks and steam generator tubes removed from the McGuire Nuclear Station. Specimen flaws were sized by post-test fractography in addition to a pre-test advanced eddy current technique. The predicted and observed test data on rupture and leak rate are compared. In general, the test failure pressures and leak rates are closer to those predicted on the basis of fractography than on nondestructive evaluation (NDE). However, the predictions based on NDE results are encouraging, particularly because they have the potential to determine a more detailed geometry of ligamented cracks, from which failure pressure and leak rate can be more accurately predicted. One test specimen displayed a time-dependent increase of leak rate under constant pressure.

Majumdar, S.; Kasza, K.; Park, J. Y.; Bakhtiari, S.

2002-06-24

366

Status of knowledge of radiation embrittlement in USA reactor pressure vessel steels  

SciTech Connect

Advances by experimental research in the USA toward an improved understanding of property changes in steel by elevated temperature (approximately 288C) irradiation are summarized. Four areas of investigation are reviewed including the confirmation and demonstration of guidelines for radiation resistant steels, the isolation of metallurgical factors contributing to variable radiation embrittlement sensitivity, the qualification of in situ heat treatments for periodic vessel embrittlement relief, and the correlation of notch ductility and fracture toughness changes with irradiation. Overall, the current state of the art provides both a high capability for tailoring steels for radiation service in new vessel construction and a promising method for controlling radiation embrittlement buildup in existing vessel construction.

Hawthorne, J.R.

1982-02-01

367

Effects of vasodilators on the systemic capacitance vessels, a study with the measurement of the mean circulatory pressure in dogs.  

PubMed

There have been yet only a few studies on the action of vasodilators on the entire systemic capacitance vessels of the living body. In the present study, we studied the action of the vasodilators on the systemic capacitance vessels by measuring the mean circulatory pressure (MCP), introduced by Guyton, and that on the systemic resistance vessels from total peripheral resistance, in anesthetized open chest dogs. We also studied the venous return curves. Depending on vasodilators and the dosages used, resistance vessels could be dilated, but capacitance vessels could not be dilated. The reverse was never true. It was also found frequently that capacitance vessels could be dilated only when the tone of the capacitance vessels have been previously elevated by norepinephrine. Again, depending on vasodilators and their dosages, the venous return curves were changed in position and/or slope. We constructed a venous return curve by connecting 2 points on the venous return-right atrial pressure (VR-RAP) plane, one, VR-RAP plot, and the other, the point of VR = 0, RAP = MCP. Changes in the venous return curve caused by these vasodilators were classified into three types; (a) a clockwise rotation with a constant MCP, where one sees no change in MCP and decreased resistance to venous return (RVR), so that one may call this RVR-type, (b) a parallel shift of the venous return curve to the left, where one sees no change in RVR but a decreased MCP, so that one may call this MCP-type and (c) a shift to the left plus clockwise rotation, where one sees a decrease in MCP and decrease in RVR, so that this is a mixture of patterns (a) and (b). One may call this the mixed-type. The existence of the response of mixed-type is worth special attention, because, in this type, cardiac output (CO) was increased by the predominant decrease in RVR in spite of a decreased MCP, leading to an important condition that the CO does not necessarily decrease when systemic capacitance vessels were dilated by the vasodilators. PMID:6232403

Ito, H; Hirakawa, S

1984-04-01

368

Effect of Dynamic Strain Aging on Fracture Characteristics of A533B-CL1 Nuclear Pressure Vessel Steel  

NASA Astrophysics Data System (ADS)

The role of interstitial impurities through dynamic strain-aging (DSA) in the upper shelf mechanical and fracture behaviors of nuclear grade pressure vessel steels was investigated using tensile, subsize Charpy three-point slow bend and single specimen (Charpy-size) unloading compliance J-integral tests. The tensile and fracture properties were studied as a function of the test temperature and applied strain -rate on the as-received pressure vessel steel material. The effect of DSA was noted to result in decreased ductility and fracture toughness of the as-received pressure vessel steel in the upper shelf region. Temperatures corresponding to fracture toughness minima and applied strain-rates followed an Arrhenius type rate equation with an activation energy identifiable with that for the diffusion of C and N in steels plus their binding energy with alloying elements such as Mn and V. Neutron irradiation suppressed DSA, resulting in improved mechanical and fracture properties of this steel in some temperature and strain-rate regimes. However, at very high temperatures, DSA exhibited embrittlement in addition to the radiation.

Jung, Youn Ho.

369

Effects of irradiation temperature on embrittlement of nuclear pressure vessel steels  

SciTech Connect

The effects of neutron irradiation on the steel reactor vessel for the modular high-temperature gas-cooled reactor (MHTGR) are being investigated, primarily because the operating temperatures are low [121 to 288{degrees}C (250--550{degrees}F)] compared to those for commercial light-water reactors (LWRs) [{approximately}288{degrees}C (550{degrees}F)]. The need for design data on the reference temperature (RT{sub NDT}) shift necessitated the irradiation at different temperatures of A 533 grade B class 1 plates, A 508 class 3 forging, and welds used for the vessel shell, vessel closure head, and vessel flange. This paper presents regular- and mini-tensile, Automated Ball Indentation (ABI), and Charpy V-notch (CVN) impact test results from five irradiation capsules of this program.

Haggag, F.M.

1992-12-31

370

Effects of irradiation temperature on embrittlement of nuclear pressure vessel steels  

SciTech Connect

The effects of neutron irradiation on the steel reactor vessel for the modular high-temperature gas-cooled reactor (MHTGR) are being investigated, primarily because the operating temperatures are low [121 to 288[degrees]C (250--550[degrees]F)] compared to those for commercial light-water reactors (LWRs) [[approximately]288[degrees]C (550[degrees]F)]. The need for design data on the reference temperature (RT[sub NDT]) shift necessitated the irradiation at different temperatures of A 533 grade B class 1 plates, A 508 class 3 forging, and welds used for the vessel shell, vessel closure head, and vessel flange. This paper presents regular- and mini-tensile, Automated Ball Indentation (ABI), and Charpy V-notch (CVN) impact test results from five irradiation capsules of this program.

Haggag, F.M.

1992-01-01

371

Yield Stress of Periclase at High Pressure and Low Temperature  

NASA Astrophysics Data System (ADS)

Magnesiowustite (Mg,Fe)O is a significant constituent of the Earth lower mantle. In a follow-up investigation of the rheological properties of MgO periclase as an analog for magnesiowustite, one powder specimen of MgO (micrometric grain size) has been investigated at pressures up to 10 GPa and temperatures ranging from 25\\deg C to 300\\deg C. The experiment was performed in a multi-anvil (SAM85, DIA-type) high-pressure apparatus, with boron epoxy as pressure medium and a BN capsule enclosing the specimen. Temperature was measured with a W3%Re-W25%Re thermocouple situated next to the sample, while the cell pressure (NaCl Decker's scale) and the stress in the sample (diffraction peak broadening, a review in Weidner, 1998) were monitored by using in-situ synchrotron X-ray diffraction at the superconductor wiggler beam line of the NSLS facility (Brookhaven, NY). The run product was investigated by Transmission Electron Microscopy (MET) using a Jeol 200 CX microscope. From the X-ray diffraction data, we infer that periclase exhibits at room temperature a transition from elastic to plastic deformation at differential stresses higher than 3 GPa. A yield stress value of just over 4 GPa was measured under these conditions. Slight sample relaxation over time was also observed during heating at 300\\deg C. Although the specimen average grain size was larger than typically 150 nm during the run, the run-product exhibits a very small average grain size (about 40 nm measured by X-ray diffraction), which suggests that nano-cracking occurred in the highly stressed material during decompression. Investigation of the run product by TEM confirms the X-ray diffraction data. Most crystals exhibit, indeed, nanometric sub-domains and numerous defects. Among these defects, the expected <110>\\{1/line{1} 0\\} slip systems have been identified and seems to dominate the deformation at high pressure and low temperature, although cleavage along the \\{001\\} planes may also have occurred at low pressure during decompression. Weidner (1998) Rheological studies at high pressure, in "Ultrahigh-pressure mineralogy: Physics and chemistry of the Earth's deep interior", R. J. Hemley Ed., Reviews in Mineralogy, vol.37, Mineralogical Society of America, Washington D.C., pp.493-524.

Schmidt, N.; Chen, J.; Raterron, P.

2001-12-01

372

Arterial stress from intraluminal pressure modified by tissue pressure offers a complete explanation for the distribution of atherosclerosis  

Microsoft Academic Search

Pressure-induced arterial stress is probably the principle factor in the localization of atherosclerotic disease. The occurrence of lesions at the bifurcations and ostia of arteries seems to be caused by the concentration of stress at these locations. Other puzzles and paradoxes regarding the distribution of atherosclerosis can be explained by dynamic extra-arterial pressure (DEAP): fluctuations in tissue pressure that occur

G. D. Saul

1999-01-01

373

Stress corrosion failure of high-pressure gas pipeline  

Microsoft Academic Search

Incidents of failure due to corrosion\\/stress corrosion cracking of high-pressure gas pipelines in Pakistan have been observed to occur after about 15–20 years of service. The present paper constitutes the failure analysis of an 18-inch diameter electric resistance-welded gas pipeline. The failure was characterized, on the basis of all the available evidence and the metallurgical examination carried out on the

F. Hasan; J. Iqbal; F. Ahmed

2007-01-01

374

COMPARING PEAK AND RESIDUAL SOIL PRESSURES MEASURED BY PRESSURE BULBS AND STRESS-STATE TRANSDUCERS  

Microsoft Academic Search

Measurement of soil compaction caused by vehicle loading is difficult and often subject to extreme variability. Two types of soil transducers were compared in an experiment conducted in a Norfolk sandy loam soil in the USDA-ARS National Soil Dynamics Laboratory's (NSDL) soil bin facilities. Stress-state transducers (SSTs), electronic transducers developed at the NSDL for measuring six directional pressures and determining

R. L. Raper; F. J. Arriaga

375

Comparing Peak and Residual Soil Pressures Measured by Pressure Bulbs and Stress-State Tranducers  

Technology Transfer Automated Retrieval System (TEKTRAN)

Measurement of soil pressures caused by vehicle loading is difficult and often subject to extreme variability. Two types of soil transducers were compared in an experiment conducted in a Norfolk sandy loam soil in the USDA-ARS National Soil Dynamics Laboratory’s (NSDL) soil bin facilities. Stress...

376

Preliminary materials selection issues for the next generation nuclear plant reactor pressure vessel.  

SciTech Connect

In the coming decades, the United States and the entire world will need energy supplies to meet the growing demands due to population increase and increase in consumption due to global industrialization. One of the reactor system concepts, the Very High Temperature Reactor (VHTR), with helium as the coolant, has been identified as uniquely suited for producing hydrogen without consumption of fossil fuels or the emission of greenhouse gases [Generation IV 2002]. The U.S. Department of Energy (DOE) has selected this system for the Next Generation Nuclear Plant (NGNP) Project, to demonstrate emissions-free nuclear-assisted electricity and hydrogen production within the next 15 years. The NGNP reference concepts are helium-cooled, graphite-moderated, thermal neutron spectrum reactors with a design goal outlet helium temperature of {approx}1000 C [MacDonald et al. 2004]. The reactor core could be either a prismatic graphite block type core or a pebble bed core. The use of molten salt coolant, especially for the transfer of heat to hydrogen production, is also being considered. The NGNP is expected to produce both electricity and hydrogen. The process heat for hydrogen production will be transferred to the hydrogen plant through an intermediate heat exchanger (IHX). The basic technology for the NGNP has been established in the former high temperature gas reactor (HTGR) and demonstration plants (DRAGON, Peach Bottom, AVR, Fort St. Vrain, and THTR). In addition, the technologies for the NGNP are being advanced in the Gas Turbine-Modular Helium Reactor (GT-MHR) project, and the South African state utility ESKOM-sponsored project to develop the Pebble Bed Modular Reactor (PBMR). Furthermore, the Japanese HTTR and Chinese HTR-10 test reactors are demonstrating the feasibility of some of the planned components and materials. The proposed high operating temperatures in the VHTR place significant constraints on the choice of material selected for the reactor pressure vessel for both the PBMR and prismatic design. The main focus of this report is the RPV for both design concepts with emphasis on material selection.

Natesan, K.; Majumdar, S.; Shankar, P. S.; Shah, V. N.; Nuclear Engineering Division

2007-03-21

377

Tachycardic vs. pharmacologic stress myocardial perfusion imaging: differential implications in multi-vessel ischemia  

PubMed Central

Background In patients unable to exercise, potential methods of induction of reversible myocardial ischemia include physiological heart rate acceleration via pacing or dobutamine infusion and asymmetric coronary vasodilatation using dipyridamole. Although their bases for induction of ischemia are widely disparate, no direct comparison of these techniques has previously been reported. Methods We performed a randomised, paired comparison of dipyridamole and pacing myocardial perfusion imaging (MPI) in 28 patients in whom exercise stress imaging was precluded, comparing the detection, localisation and quantitation of ischemia. Results Reversible myocardial ischemia was detected in 21 patients, concordantly in 13 (p = 0.042). There was a high degree of concordance (p < 0.0001) regarding locations of sites of ischemia. While there was a good correlation (r = 0.74, p < 0.0001) between size of total ischemic zones with dipyridamole and pacing, the magnitude of ischemia tended to be greater with dipyridamole (mean percentage of left ventricular myocardium ± SD, 9.4 ± 11.0% vs. 7.0 ± 9.0%, p = 0.091). Furthermore, this difference resulted from accentuation of the primary ischemic zone with dipyridamole in patients with multi-vessel ischemia (mean ± SD, 28.1 ± 21.1% vs. 18.7 ± 16.1%, p = 0.046). Conclusions Despite major differences in mechanism(s) of induction of ischemia, dipyridamole and pacing produce similar results regarding detection, localisation and severity of ischemia. However, dipyridamole accentuates ischemia in primary (vs. secondary) ischemic zones, consistent with known induction of coronary “steal". This should be taken into account in interpretation of scan results.

Nguyen, Thanh H; Horowitz, John D; Unger, Steven A

2012-01-01

378

NRL-EPRI research program (RP886-2), evaluation and prediction of neutron embrittlement in reactor pressure vessel materials. Annual progress report for CY 1978  

Microsoft Academic Search

Nuclear reactor pressure vessel materials are subject to progressive reductions in fracture resistance in service due to neutron irradiation. Current technology is inadequate to quantitatively predict radiation embrittlement for all vessel materials and their metallurgical variations for the neutron fluences of interest. In addition a relationship between apparent notch ductility and fracture toughness in the irradiated condition is needed to

Hawthorne

1979-01-01

379

Blood Pressure and Heart Rate Responses to Anticipated High-stress Dental Treatment  

Microsoft Academic Search

Twenty-four healthy adults participated in a study to determine the effects of anticipated high-stress dental treatment on blood pressure and heart rate. Blood pressure, heart rate, and state anxiety were assessed prior to four consecutive dental appointments. Appointments 1, 2, and 4 were of relatively low stress and appointment 3 was of relatively high stress. Blood pressure was unaffected while

Frank M. Beck; Joël M. Weaver

1981-01-01

380

Status of knowledge of radiation embrittlement in US reactor pressure vessels steels  

SciTech Connect

Advances in experimental research in the United States toward an improved understanding of property changes in steel by elevated temperature (about 288/sup 0/C) irradiation are summarized. Four areas of investigation are reviewed, including the confirmation and demonstration of guidelines for radiation-resistant steels, the isolation of metallurgical factors contributing to variable radiation embrittlement sensitivity, the qualification of in situ heat treatments for periodic vessel embrittlement relief, and the correlation of notch ductility and fracture toughness changes with irradiation. Overall, the current state of the art provides both a high capability for tailoring steels for radiation service in new vessel construction and a promising method for controlling radiation embrittlement buildup in existing vessel construction.

Hawthorne, J.R.

1981-10-01

381

Status of knowledge of radiation embrittlement in U. S. reactor pressure vessel steels  

SciTech Connect

Advances in experimental research in the United States toward an improved understanding of property changes in steel by elevated temperature ( about 288/sup 0/ C) irradiation ar summarized. Four areas of investigation are reviewed, including the confirmation and demonstration of guidelines for radiation-resistant steels, the isolation of metallurgical factors contributing to variable radiation embrittlement sensitivity, the qualification of in situ heat treatments for periodic vessel embrittlement relief, and the correlation of notch ductility and fracture toughness changes with irradiation. Overall, the current state of the art provides both a high capability for tailoring steels for radiation service in new vessel construction and a promising method for controlling radiation embrittlement buildup in existing vessel construction.

Hawthorne, J.R.

1981-10-01

382

Method for determining pore pressure and horizontal effective stress from overburden and effective vertical stresses  

Microsoft Academic Search

This patent describes a method for determining pore pressure in an in-situ subsurface formation. It comprises: causing a well logging tool to traverse an earth borehole between the earth's surface and the subsurface formation; determining the total overburden stress resulting from the integrated weight of material overlying the subsurface formation between the earth's surface and the subsurface formation. The overburden

P. Holbrook; H. A. Robertson; M. L. Hauck

1990-01-01

383

Untersuchung zur Wasserstoffversproedung von Staehlen fuer Wasserstoffstahlflaschen und Druckbehaelter (Investigation of the Hydrogen Embrittlement of Steels for Hydrogen Steel Cylinders and Pressure Vessels.  

National Technical Information Service (NTIS)

Investigations were made on the hydrogen embrittlement of chrome-molybdenum alloyed pressure vessel steels by using hollow specimens in tensile tests with constant strain rates. For comparison, tests were carried out with nitrogen, too.

R. Buechsenschuetz K. Dieser

1983-01-01

384

Damage dosimetry and embrittlement monitoring of nuclear pressure vessels in real time by magnetic properties measurement. Technical progress report for year 2, October 1, 1991--September 30, 1992  

SciTech Connect

The objective of this project is to develop a technique for real-time monitoring of neutron dose and of the onset and progression of embrittlement in operating nuclear pressure vessels. The technique relies on the measurement of magnetic properties of steel and other magnetic materials which are extremely sensitive to radiation-induced properties changes. The approach being developed here is innovative and unique. It promises to be readily applicable to all existing and planned reactor structures. The significance of this program is that it addresses a major concern in the operation of existing nuclear pressure vessels. The development of microscopic defect clusters during irradiation in the nuclear pressure vessel beltline region leads to an increase in material yield strength and a concomitant decrease in ductility, or ability to absorb energy in fracture (i.e. fracture toughness). This decrease in fracture toughness is alarming since it may impair the ability of the pressure vessel to resist fracture during unusual loading situations.

Stubbins, J.F.; Ougouag, A.M.; Williams, J.G.

1992-07-01

385

Analytical modeling of the effect of crack depth, specimen size, and biaxial stress on the fracture toughness of reactor vessel steels  

NASA Astrophysics Data System (ADS)

Fracture, toughness values for A533-B reactor pressure vessel (RPV) steel obtained from test programs at Oak Ridge National Laboratory (ORNL) and University of Kansas (KU) are interpreted using the J-A(sub 2) analytical model. The analytical model is based on the critical stress concept and takes into consideration the constraint effect using the second parameter A(sub 2) in addition to the generally accepted first parameter J which represents the loading level. It is demonstrated that with the constraint level included in the model effects of crack depth (shallow vs deep), specimen size (small vs. large), and loading type (uniaxial vs biaxial) on the fracture toughness from the test programs can be interpreted and predicted.

Chao, Yuh-Jin; Lam, Poh-Sang

1995-02-01

386

Analysis of designs for coal-conversion pressure vessels. Part III. Summary of activities. Final report. [Project personnel, companies visited, technical reports, journal articles and theses  

Microsoft Academic Search

This report summarizes the activities of a research project entitled Analysis of Designs for Coal Conversion Pressure Vessels, conducted at the University of Kentucky under the sponsorship of the Department of Energy (Contract DE-AS05-77ET05378). The objective of the project is to conduct a comprehensive study of alternate structural designs for large pressure vessels for use in processes for gasification and

D. C. Leigh; T. R. Tauchert

1980-01-01

387

Three-dimensional discrete ordinates radiation transport calculations of neutron fluxes for beginning-of-cycle at several pressure vessel surveillance positions in the high flux isotope reactor  

SciTech Connect

The objective of this research was to determine improved thermal, epithermal, and fast fluxes and several responses at mechanical test surveillance location keys 2, 4, 5, and 7 of the pressure vessel of the Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR) for the beginning of the fuel cycle. The purpose of the research was to provide essential flux data in support of radiation embrittlement studies of the pressure vessel shell and beam tubes at some of the important locations.

Pace, J.V. III; Slater, C.O.; Smith, M.S.

1993-11-01

388

Residual stress effects in containment analysis.  

SciTech Connect

The manufacturing of steel containment vessels starts with the forming of flat plates into curved plates. A steel containment structure is made by welding individual plates together to form the sections that make up the complex shaped vessels. The metal forming and welding process leaves residual stresses in the vessel walls. Generally, the effect of metal forming residual stresses can be reduced or virtually eliminated by thermally stress relieving the vessel. In large containment vessels this may not be practical and thus, the residual stresses due to manufacturing may become important. The residual stresses could possibly affect the response of the vessel to internal pressurization. When the level of residual stresses is significant it will affect the vessel's response, for instance the yielding pressure and possibly the failure pressure. This paper will address the effect of metal forming residual stresses on the response of a generic pressure vessel to internal pressurization. A scoping analysis investigated the effect of residual forming stresses on the response of an internally pressurized vessel. A simple model was developed to gain understanding of the mechanics of the problem. Residual stresses due to the welding process were not considered in this investigation.

Pfeiffer, P. A.

1998-04-24

389

Aging impact on the safety and operability of nuclear reactor pressure vessels  

Microsoft Academic Search

Irradiation embrittlement causes a loss of reactor vessel material fracture toughness as nuclear plants age. Fracture mechanics based regulatory requirements limit the permissible level of irradiation embrittlement such that essential fracture prevention margins are maintained throughout the plant operating life. This paper reviews the regulatory requirements and the underlying fracture mechanics technology. Issues identified with that technology are identified and

Pennell

1992-01-01

390

Pressure Vessel Investigations of the Former Greifswald NPP: Fluence Calculations and Niobium Based Fluence Measurements  

SciTech Connect

Pressure vessel integrity assessment after long-term service irradiation is commonly based on surveillance program results. Nevertheless, only the investigation of RPV material from decommissioned NPPs enables the evaluation of the real toughness response. Such a chance is given now through the investigation of material from the former Greifswald NPP (VVER-440/230) to evaluate the material state of a standard RPV design and to assess the quality of prediction rules and assessment tools. The operation of the four Greifswald units was finished in 1991 after 12--15 years of operation. In autumn 2005 the first trepans (diameter 120 mm) were gained from the unit 1 of this NPP. Some details of the trepanning procedure will be given. The paper mainly deals with the retrospective dosimetry based on Niobium, which is a trace element of the RPV material. The reaction {sup 93}Nb(n,n'){sup 93m}Nb with an energy dependence highly correlated to radiation damage and a half life of the reaction product of 16.13 years is well suited for retrospective fast neutron dosimetry. Fluence calculations using the code TRAMO were based on pin-wise time dependent neutron sources and an updated nuclear data base (ENDF/B-VI release 8). The neutron spectra were determined at the trepan positions. The different loading schemes of unit 1 (standard and with 4 or 6 dummy assemblies) were taken into account. The calculated specific {sup 93m}Nb activities for February, 2006 at the sample positions were determined to 16.3 Bq/{mu}g Nb for sample 1, (0.1 cm distance from inner wall), and 4.0 Bq/{mu}g Nb for sample 2 (11.5 cm distance from inner wall). Unfortunately, a second neutron reaction besides {sup 93}Nb(n,n') leading to {sup 93m}Nb-activity is the reaction {sup 92}Mo(n,{gamma}){sup 93}Mo. {sup 93}Mo decays by electron capture to {sup 93m}Nb with a half life of 4000 years and a branching ratio b{sub r} = 0.88. As (n,{gamma})-reactions are produced mainly by low energy neutrons, being less important for material damage, the {sup 93m}Nb-activity generated through the Mo-path should be determined separately and subtracted from the measured activity. For the sample 1 in the maximum flux azimuthal position of weld SN4 with a Nb-content of 8 ppm and an Mo-content of 4000 ppm for February 3, 2006 was obtained a Mo-induced {sup 93m}Nb-activity of 80 Bq/g steel, amounting to 37.7% of the total {sup 93m}Nb-activity. It turns out that the {sup 93m}Nb generation on the second path is nearly of the same order as the fast neutron induced generation from Niobium. For the experimental determination of the {sup 93m}Nb-activity the Nb-content was determined by ICP-MS (inductive coupled plasma mass spectrometry) after dissolution of the material sample. The radiochemical isolation of Nb was done by anion exchange separation. The radiochemical separation was accompanied by determination of the chemical yield of Nb using again the ICP-MS method. The measurement of the {sup 93m}Nb activity was realized by Liquid Scintillation Spectrometry (LSC). The first comparison between the calculated and the measured {sup 93m}Nb activities resulted in deviations between 15 and 50%. Possible reasons for the observed differences are discussed. (authors)

Konheiser, J.; Rindelhardt, U.; Viehrig, H.W.; Boehmer, B. [Forschungszentrum Dresden-Rossendorf e.V. Bautzner Landstrasse 128, P.O. Box 510119, 01314 Dresden (Germany); Gleisberg, B. [VKTA, Bautzner Landstrasse 128 (B6), D-01328 Dresden (Germany)

2006-07-01

391

Structural Analysis of the NCSX Vacuum Vessel  

SciTech Connect

The NCSX (National Compact Stellarator Experiment) vacuum vessel has a rather unique shape being very closely coupled topologically to the three-fold stellarator symmetry of the plasma it contains. This shape does not permit the use of the common forms of pressure vessel analysis and necessitates the reliance on finite element analysis. The current paper describes the NCSX vacuum vessel stress analysis including external pressure, thermal, and electro-magnetic loading from internal plasma disruptions and bakeout temperatures of up to 400 degrees centigrade. Buckling and dynamic loading conditions are also considered.

Fred Dahlgren; Art Brooks; Paul Goranson; Mike Cole; Peter Titus

2004-09-28

392

Test results on direct containment heating by high-pressure melt ejection into the Surtsey vessel: The TDS test series  

SciTech Connect

The Technology Development and Scoping (TDS) test series was conducted to test and develop instrumentation and procedures for performing steam-driven, high-pressure melt ejection (HPME) experiments at the Surtsey Test Facility to investigate direct containment heating (DCH). Seven experiments, designated TDS-1 through TDS-7, were performed in this test series. These experiments were conducted using similar initial conditions; the primary variable was the initial pressure in the Surtsey vessel. All experiments in this test series were performed with a steam driving gas pressure of {approx_equal} 4 MPa, 80 kg of lumina/iron/chromium thermite melt simulant, an initial hole diameter of 4.8 cm (which ablated to a final hole diameter of {approx_equal} 6 cm), and a 1/10th linear scale model of the Surry reactor cavity. The Surtsey vessel was purged with argon (<0.25 mol% O{sub 2}) to limit the recombination of hydrogen and oxygen, and gas grab samples were taken to measure the amount of hydrogen produced.

Allen, M.D.; Blanchat, T.K.; Pilch, M.M. [Sandia National Lab., Albuquerque, NM (United States). Severe Accident Phenomenology

1994-08-01

393

Use of miniature and standard specimens to evaluate effects of irradiation temperature on pressure vessel steels  

SciTech Connect

The effects of neutron irradiation on the steel reactor vessel for the modular high-temperature gas-cooled reactor (MHTGR) are being investigated, primarily because the operating temperatures are low (121 to 210{degrees}C (250--410{degrees}F)) compared to those for commercial light-water reactors (LWRs) ({approximately}288{degrees}C (550{degrees}F)). The need for design data on the reference temperature shift necessitated the irradiation at different temperatures of A 533 grade B class 1 plate. A 508 class 3 forging, and welds used for the vessel shell, vessel closure head, the vessel flange. This paper presents results from the first four irradiation capsules of this program. The four capsules were irradiated in the University of Buffalo Reactor to an effective fast fluence of 1 {times}10{sup 18} neutron/cm{sup 2} (0.68 {times} 10{sup 18} neutron/cm{sup 2} (>1 MeV)) at temperatures of 288, 204, 163, and 121{degrees}C (550, 400, 325, and 250{degrees}F), respectively. The yield and ultimate strengths of both steel plate materials of the MHTGR Program increased with decreasing irradiation temperature. Similarly, the 41-J Charpy V-notch (CVN) transition temperature shift increased with decreasing irradiation temperature (in agreement with the increase in yield strength). The miniature tensile and automated ball indentation (ABI) test results (yield strength and flow properties) were in good agreement with those from standard tensile specimens. The miniature tensile and ABI test results were also used in a model that utilizes the changes in yield strength to estimate the CVN ductile-to-brittle transition temperature shift due to irradiation. The model predictions were compared with CVN test results obtained here and in earlier work. 5 refs., 11 figs., 6 tabs.

Haggag, F.M.; Nanstad, R.K. (Oak Ridge National Lab., TN (United States)); Byrne, S.T. (ABB/Combustion Engineering, Inc., Windsor, CT (United States))

1991-01-01

394

Programmable Calculator Stress Analysis.  

National Technical Information Service (NTIS)

Advanced programmable alphanumeric calculators are well suited for closed-form calculation of pressure-vessel stresses. They offer adequate computing power, portability, special programming features, and simple interactive execution procedures. Representa...

L. A. Van Gulick

1983-01-01

395

Programmable calculator stress analysis  

SciTech Connect

This paper assesses the suitability of advanced programmable alphanumeric calculators for closed form calculation of pressure vessel stresses and offers, as their advantages, adequate computing power, portability, special programming features, and simple interactive execution procedures. Representative programs which demonstrate their capacities are presented. Problems dealing with stress and strength calculations in thick-walled pressure vessels and with the computation of stresses near head/pressure vessel junctures are treated. Assessed favorably in this paper as useful contributors to computeraided design of pressure vessels, programmable alphanumeric calculators have areas of implementation in checking finite element results, aiding in the development of an intuitive understanding of stresses and their parameter dependencies, and evaluating rapidly a variety of preliminary designs.

Van Gulick, L.A.

1983-01-01

396

Burst pressure prediction in graphite/epoxy pressure vessels using neural networks and acoustic emission amplitude data  

SciTech Connect

A burst pressure prediction model was generated from the acoustic emission amplitude distribution data taken during hydroproof for three sets of ASTM standard 145 mm (5.75 in.) diameter filament wound graphite/epoxy bottles. The three sets of bottles featured the same design parameters and were wound from the same graphite fiber, the only difference being in the epoxies used. Therefore, the three resin types were categorized using dummy variables, which allowed the prediction of burst pressures in all three sets of bottles using a single back-propagation neural network. Three bottles from each set were used to train the network. The resin category and the acoustic emission amplitude distribution data taken up to 25 percent of the expect burst pressure were used as network inputs. The actual burst pressures were supplied as target values for the supervised training phase. Architecturally, the network consisted of a 48 neuron input layer (a categorical variable defining the resin type, plus 47 integer variables for the acoustic emission amplitude distribution frequencies), a 15 neural hidden layer for mapping, and a single output neuron for burst pressure prediction. The network, trained on three bottles from each resin type, was able to predict burst pressures in the remaining bottles with a worst case error of {minus}3.89 percent, well within the desired goal of {+-}5 percent.

Hill, E.V.K [Embry-Riddle Aeronautical Univ., Daytona Beach, FL (United States). Aerospace Engineering Dept.; Walker, J.L. II [Univ. of Alabama, Huntsville, AL (United States). Dept. of Mechanical and Aerospace Engineering; Rowell, G.H. [Lander Univ., Greenwood, SC (United States). Dept. of Mathematics and Computer Science

1996-06-01

397

Noninvasive identification of left main and triple vessel coronary artery disease: improved accuracy using quantitative analysis of regional myocardial stress distribution and washout of thallium-201  

SciTech Connect

The capabilities of visual and quantitative analysis of stress redistribution thallium-201 scintigrams, exercise electrocardiography and exercise blood pressure response were compared for correct identification of extensive coronary disease, defined as left main or triple vessel coronary artery disease, or both (50% or more luminal diameter coronary narrowing), in 105 consecutive patients with suspected coronary artery disease. Extensive disease was present in 56 patients and the remaining 49 had either less extensive coronary artery disease (n = 34) or normal coronary arteriograms (n = 15). Although exercise blood pressure response, exercise electrocardiography and visual thallium-201 analysis were highly specific (98, 88 and 96%, respectively), they were insensitive for identification of patients with extensive disease (14, 45 and 16%, respectively). Quantitative thallium-201 analysis significantly improved the sensitivity of visual thallium-201 analysis for identification of patients with extensive disease (from 16 to 63%, p less than 0.001) without a significant loss of specificity (96 versus 86%, p = NS). Eighteen (64%) of the 28 patients who were misclassified by visual analysis as having less extensive disease were correctly classified as having extensive disease by virtue of quantitative analysis of regional myocardial thallium-201 washout. When the results of quantitative thallium-201 analysis were combined with those of blood pressure and electrocardiographic response to exercise, the sensitivity and specificity for identification of patients with extensive disease was 86 and 76%, respectively, and the highest overall accuracy (0.82) was obtained.

Maddahi, J.; Abdulla, A.; Garcia, E.V.; Swan, H.J.; Berman, D.S.

1986-01-01

398

Activation of Peripheral Opioid ?-Receptors in Blood Vessel May Lower Blood Pressure in Spontaneously Hypertensive Rats  

Microsoft Academic Search

Background\\/Aims: The role of opioid receptors in the regulation of vascular function remains unclear. In the current study, we evaluated the ability of loperamide, a peripheral opioid receptor agonist, to regulate blood pressure in spontaneously hypertensive rats (SHRs) and examined the mechanism(s) by which loperamide exerts its effects. Methods: In male SHRs, mean arterial pressure (MAP) was measured and hemodynamic

Zhih-Cherng Chen; Ja-Ping Shieh; Hsien-Hui Chung; Ching-Hsia Hung; Hung Jung Lin; Juei-Tang Cheng

2011-01-01

399

Low-alloy steels for thick-walled pressured vessels. Final report, October 1, 1978-March 31, 1980  

SciTech Connect

This program aims to modify existing commercially available pressure vessel steels and to develop new steels which can be field fabricated into thick sectioned pressure vessels for coal gasification and liquefaction systems. During 1978-79, transmission electron microscopy has been carried out on 2.25Cr-1Mo, samples of which have been cooled at rates simulating those obtained in commercial plates up to 16 in. thick. The tempering responses at different temperatures have also been fully characterised. These studies were repeated on the alloy modifications. Programs have been developed to eliminate temper embrittlement in 2.25Cr-1Mo and also in 3.5Ni-1.5Cr steels and a study of the microstructural aspects of weldability has also been initiated. Fracture mechanics studies have been initiated on A533B and its alloy modifications. Isothermal transformation of Alloy 4 (Fe-0.1%C-0.5V-0.5Mn) and Alloy 5 (Fe-0.1C-0.5V-0.5Mn-3Ni) showed that uniform VC particle dispersions with optimum strength and toughness properties could be achieved in Alloy (i.e. by addition of 3%Ni). Preliminary investigations indicate that this VC dispersion can also be produced during slow cooling, especially at rates equivalent to those for 12 to 16'' thick plates. 30 figures, 11 tables.

Todd, J.A.; Zackay, V.F.; Parker, E.R.

1980-01-01

400

High Stress Responsivity Predicts Later Blood Pressure Only in Combination With Positive Family History and High Life Stress  

Microsoft Academic Search

High cardiovascular responsivity to stressors has not consistently improved prediction of later blood pressure increases beyond the predictive effects of baseline pressure. Animal models suggest that genetic susceptibility to hypertension and frequent stress exposure are important modulating factors in stress-related hypertension. Thus in 103 men originally tested at age 18 to 22 years and reassessed 10 years later, interactive effects

Kathleen C. Light; Susan S. Girdler; Andrew Sherwood; Edith E. Bragdon; Kimberly A. Brownley; Sheila G. West; Alan L. Hinderliter

401

BIOASSAY VESSEL FAILURE ANALYSIS  

Microsoft Academic Search

Two high-pressure bioassay vessels failed at the Savannah River Site during a microwave heating process for biosample testing. Improper installation of the thermal shield in the first failure caused the vessel to burst during microwave heating. The second vessel failure is attributed to overpressurization during a test run. Vessel failure appeared to initiate in the mold parting line, the thinnest

Vormelker

2008-01-01

402

Analog experiments on magma-filled cracks: Competition between external stresses and internal pressure  

Microsoft Academic Search

We have performed two series of analog experiments using gelatin to study the propagation of liquid-filled cracks in stressed medium. The first series was designed to study the competition between the external stress and the liquid excess pressure in controlling the propagation direction. We systematically controlled the external stress and the liquid excess pressure by changing the surface load and

Tohru Watanabe; Takayuki Masuyama; Kazuhiro Nagaoka; T. Tahara

2002-01-01

403

Application of stress-pore pressure coupling theory for porous media to the Xinfengjiang reservoir earthquakes  

Microsoft Academic Search

Theory of the coupling of stress-pore pressure in the saturated, elastic porous media is used in the study of the formation mechanism of the Xinfengjiang reservoir-induced earthquakes. Based on the results, it is believed that compared with the mechanism of additional stress in the vicinity of the reservoir, the mechanism of the coupling of additional stress and pore pressure may

Li-Ying Shen; Bao-Qi Chang

1995-01-01

404

Estimation of Inelastic Behavior for a Tapered Nozzle in Vessel due to Thermal Transient Load using Stress Redistribution Locus Method  

NASA Astrophysics Data System (ADS)

Simplified inelastic design procedures have been required to reduce simulation cost and to shorten the development period for the modern high temperature machines and structures. Stress redistribution locus (SRL) method has been proposed to provide a reasonable solution employing both the elastic Finite Element (FE) analysis and a unique hyperbolic curve. In the SRL method, dimensionless stress and strain that were normalized using the inelastic stress/strain and the corresponding elastic stress/strain were introduced. This methodology is based on the fact that the stress distribution in well deformed or in high temperature components changes with deformation or time and that the dimensionless stress-strain relation traces a kind of the elastic follow-up locus in spite of the constitutive equation of the material. In this paper, FE analyses incorporating plasticity and creep were performed for a tapered nozzle of a reactor vessel under some thermal transient loads. The dimensionless stress-strain relation was compared with a conventional and newly proposed SRL curves. FE analysis results showed there to be a critical point in the tapered nozzle due to the thermal transient load dependant on a descending rate of temperature from the higher temperature in the operation cycle. Whenever a certain amount of inelastic strain in the nozzle is produced in a restricted area, the dimensionless stress-strain relation is depicted inside the presently proposed SRL curve. Thus the appropriate coefficient in the SRL method is found to be greater than the proposed one, and the present criterion guarantees robust structures for complicated components involving inelastic deformation.

Kobayashi, Ken-Ichi; Yamada, Jun-Ichi

405

Subjective Stress and Coping Resources Interact To Predict Blood Pressure Reactivity in Black College Students.  

ERIC Educational Resources Information Center

|Examined the effects of subjective stress and coping resources on blood pressure reactivity among black college students. The interactive effects of subjective stress and coping resources predicted diastolic blood pressure reactivity. Higher levels of problem-focused coping related to more marked diastolic blood pressure changes under conditions…

Clark, Rodney

2003-01-01

406

Heat-stress-induced changes in central venous pressure do not explain interindividual differences in orthostatic tolerance during heat stress  

PubMed Central

The extent to which heat stress compromises blood pressure control is variable among individuals, with some individuals becoming very intolerant to a hypotensive challenge, such as lower body negative pressure (LBNP) while heat stressed, while others are relatively tolerant. Heat stress itself reduces indexes of ventricular filling pressure, including central venous pressure, which may be reflective of reductions in tolerance in this thermal condition. This study tested the hypothesis that the magnitude of the reduction in central venous pressure in response to heat stress alone is related to the subsequent decrement in LBNP tolerance. In 19 subjects, central hypovolemia was imposed via LBNP to presyncope in both normothermic and heat-stress conditions. Tolerance to LBNP was quantified using a cumulative stress index (CSI), and the difference between normothermic CSI and heat-stress CSI was calculated for each individual. The eight individuals with the greatest CSI difference between normothermic and heat-stress tolerances (LargeDif), and the eight individuals with the smallest CSI difference (SmallDif), were grouped together. By design, the difference in CSI between thermal conditions was greater in the LargeDif group (969 vs. 382 mmHg × min; P < 0.001). Despite this profound difference in the effect of heat stress in decreasing LBNP tolerance between groups, coupled with no difference in the rise in core body temperatures to the heat stress (LargeDif, 1.4 ± 0.1°C vs. SmallDif, 1.4 ± 0.1°C; interaction P = 0.89), the reduction in central venous pressure during heat stress alone was similar between groups (LargeDif: 5.7 ± 1.9 mmHg vs. SmallDif: 5.2 ± 2.0 mmHg; interaction P = 0.85). Contrary to the proposed hypothesis, differences in blood pressure control during LBNP are not related to differences in the magnitude of the heat-stress-induced reductions in central venous pressure.

Brothers, R. Matthew; Keller, David M.; Wingo, Jonathan E.; Ganio, Matthew S.

2011-01-01

407

Differential effects of alprazolam and clonazepam on the immune system and blood vessels of non-stressed and stressed adult male albino rats  

PubMed Central

Benzodiazepines belongs to one of the most commonly used anxiolytic and anticonvulsant drugs in the world. Full description of toxic effects on different organs is lacking for nearly all the current benzodiazepines. The aim of the current work was to study the immunologic and vascular changes induced by sub-chronic administration of alprazolam and clonazepam in non-stressed and stressed adult male albino rats. Forty-two adult male albino rats were divided into 6 groups (I): (Ia) Negative control rats, (Ib): Positive control rats received distilled water, (II): Stressed rats, (III): Non-stressed rats received daily oral dose of clonazepam (0.5 mg/kg), (IV): Stressed rats received daily oral dose of clonazepam (0.5 mg/kg), (V): Non-stressed rats received daily oral dose of alprazolam (0.3 mg/kg). (VI): Stressed rats received daily oral dose of alprazolam (0.3 mg/kg). At the end of the 4th week, total leukocyte count (WBCs) and differential count were determined, anti-sheep RBC antibody (Anti-SRBC) titer and interleukin-2 (IL-2) level were assessed, thymus glands, lymph nodes, spleens and abdominal aortae were submitted to histopathological examination. Alprazolam was found to induce a significant increase in neutrophil count and a significant decrease in lymphocytes, anti-SRBC titer and IL-2 level with severe depletion of the splenic, thymal and nodal lymphocytes, accompanied by congestion and eosinophilic vasculitis of all organs tested in comparison to clonazepam treated rats. Stress enhanced the toxic effects. It was concluded that the immune system and blood vessels can be adversely affected to a greater extent by short-term chronic administration of alprazolam than by clonazepam, and these toxic effects are aggravated by stress.

Elmesallamy, Ghada E.; Abass, Marwa A.; Ahmed Refat, Nahla A.G.; Atta, Amal H.

2011-01-01

408

Role of Crack Arrest in the Evaluation of PWR Pressure Vessel Integrity During PTS Transients.  

National Technical Information Service (NTIS)

The HSST program is investigating flaw behavior in large cylinders and is also obtaining fracture-mechanics-related material properties, while the Integrated Pressurized Thermal-Shock (IPTS) program is primarily concerned with an estimation of the overall...

R. D. Cheverton D. G. Ball

1984-01-01

409

Assessment of the advantages of a residual heat removal system inside the reactor pressure vessel.  

National Technical Information Service (NTIS)

In the framework of research on diversified means for removing the residual heat from pressurized water reactors, the CEA is studying a passive system called RRP (Refroidissement du Reacteur au Primaire, or primary circuit cooling system), which includes ...

G. M. Gautier

1995-01-01

410

PEG-albumin supraplasma expansion is due to increased vessel wall shear stress induced by blood viscosity shear thinning  

PubMed Central

We studied the extreme hemodilution to a hematocrit of 11% induced by three plasma expanders: polyethylene glycol (PEG)-conjugated albumin (PEG-Alb), 6% 70-kDa dextran, and 6% 500-kDa dextran. The experimental component of our study relied on microelectrodes and cardiac output to measure both the rheological properties of plasma-expander blood mixtures and nitric oxide (NO) bioavailability in vessel walls. The modeling component consisted of an analysis of the distribution of wall shear stress (WSS) in the microvessels. Our experiments demonstrated that plasma expansion with PEG-Alb caused a state of supraperfusion with cardiac output 40% above baseline, significantly increased NO vessel wall bioavailability, and lowered peripheral vascular resistance. We attributed this behavior to the shear thinning nature of blood and PEG-Alb mixtures. To substantiate this hypothesis, we developed a mathematical model of non-Newtonian blood flow in a vessel. Our model used the Quemada rheological constitutive relationship to express blood viscosity in terms of both hematocrit and shear rate. The model revealed that the net effect of the hemodilution induced by relatively low-viscosity shear thinning PEG-Alb plasma expanders is to reduce overall blood viscosity and to increase the WSS, thus intensifying endothelial NO production. These changes act synergistically, significantly increasing cardiac output and perfusion due to lowered overall peripheral vascular resistance.

Sriram, Krishna; Tsai, Amy G.; Cabrales, Pedro; Meng, Fantao; Acharya, Seetharama A.; Tartakovsky, Daniel M.

2012-01-01

411

PEG-albumin supraplasma expansion is due to increased vessel wall shear stress induced by blood viscosity shear thinning.  

PubMed

We studied the extreme hemodilution to a hematocrit of 11% induced by three plasma expanders: polyethylene glycol (PEG)-conjugated albumin (PEG-Alb), 6% 70-kDa dextran, and 6% 500-kDa dextran. The experimental component of our study relied on microelectrodes and cardiac output to measure both the rheological properties of plasma-expander blood mixtures and nitric oxide (NO) bioavailability in vessel walls. The modeling component consisted of an analysis of the distribution of wall shear stress (WSS) in the microvessels. Our experiments demonstrated that plasma expansion with PEG-Alb caused a state of supraperfusion with cardiac output 40% above baseline, significantly increased NO vessel wall bioavailability, and lowered peripheral vascular resistance. We attributed this behavior to the shear thinning nature of blood and PEG-Alb mixtures. To substantiate this hypothesis, we developed a mathematical model of non-Newtonian blood flow in a vessel. Our model used the Quemada rheological constitutive relationship to express blood viscosity in terms of both hematocrit and shear rate. The model revealed that the net effect of the hemodilution induced by relatively low-viscosity shear thinning PEG-Alb plasma expanders is to reduce overall blood viscosity and to increase the WSS, thus intensifying endothelial NO production. These changes act synergistically, significantly increasing cardiac output and perfusion due to lowered overall peripheral vascular resistance. PMID:22505638

Sriram, Krishna; Tsai, Amy G; Cabrales, Pedro; Meng, Fantao; Acharya, Seetharama A; Tartakovsky, Daniel M; Intaglietta, Marcos

2012-04-13

412

Potential impact of enhanced fracture-toughness data on fracture mechanics assessment of PWR vessel integrity for pressurized thermal shock  

SciTech Connect

The Heavy Section Steel Technology (HSST) Program is involved with the generation of enhanced fracture-initiation toughness and fracture-arrest toughness data of prototypic nuclear reactor vessel steels. These two sets of data are enhanced because they have distinguishing characteristics that could potentially impact PWR pressure vessel integrity assessments for the pressurized-thermal shock (PTS) loading condition which is a major plant-life extension issue to be confronted in the 1990's. A series of large-scale fracture-mechanics experiments have produced crack-arrest (K{sub Ia}) data with the distinguishing characteristic that the values are considerably above 220 MPA {center dot} {radical}m. The implicit limit of the ASME Code and the limit used in the Integrated Pressurized Thermal Shock (IPTS) studies. Currently, the HSST Program is planning experiments to verify and quantify for A533B steel the distinguishing characteristic of elevated the distinguishing characteristic of elevated initiation-fracture toughness for shallow flaws which has been observed for other steels. The results of the analyses indicated that application of the enhanced K{sub Ia} data does reduce the conditional probability of failure P(F{vert bar}E); however, it does not appear to have the potential to significantly impact the results of PTS analyses. The application of enhanced fracture-initiation-toughness data for shallow flaws also reduces P(F{vert bar}E), and does appear to have a potential for significantly affecting the results of PTS analyses. 19 refs., 11 figs., 1 tab.

Dickson, T.L.; Theiss, T.J.

1991-01-01

413

Arterial stress from intraluminal pressure modified by tissue pressure offers a complete explanation for the distribution of atherosclerosis.  

PubMed

Pressure-induced arterial stress is probably the principle factor in the localization of atherosclerotic disease. The occurrence of lesions at the bifurcations and ostia of arteries seems to be caused by the concentration of stress at these locations. Other puzzles and paradoxes regarding the distribution of atherosclerosis can be explained by dynamic extra-arterial pressure (DEAP): fluctuations in tissue pressure that occur with movement, body position, and the beating of the heart. These tissue pressures, both above and below atmospheric pressure, change the transmural pressures in arteries and thereby either retard or accelerate atherogenesis. The DEAP hypothesis predicts that physical fitness increases extra-arterial tissue pressure, which protects important arteries from high transmural pressure. Deconditioning is expected to have the exact opposite effect, producing the equivalent of localized hypertension in the cerebral, internal carotid, coronary, abdominal aorta, and lower extremity arteries. PMID:10465674

Saul, G D

1999-04-01

414

Next Generation Nuclear Plant Reactor Pressure Vessel Materials Research and Development Plan (PLN-2803)  

SciTech Connect

The U.S. Department of Energy (DOE) has selected the High-Temperature Gas-cooled Reactor (HTGR) design for the Next Generation Nuclear Plant (NGNP) Project. The NGNP will demonstrate the use of nuclear power for electricity and hydrogen production, with an outlet gas temperature in the range of 750°C, and a design service life of 60 years. The reactor design will be a graphite-moderated, helium-cooled, prismatic, or pebble bed reactor and use low-enriched uranium, Tri-Isotopic (TRISO)-coated fuel. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during accidents. Selection of the technology and design configuration for the NGNP must consider both the cost and risk profiles to ensure that the demonstration plant establishes a sound foundation for future commercial deployments. The NGNP challenge is to achieve a significant advancement in nuclear technology while setting the stage for an economically viable deployment of the new technology in the commercial sector soon after 2020. This technology development plan details the additional research and development (R&D) required to design and license the NGNP RPV, assuming that A 508/A 533 is the material of construction. The majority of additional information that is required is related to long-term aging behavior at NGNP vessel temperatures, which are somewhat above those commonly encountered in the existing database from LWR experience. Additional data are also required for the anticipated NGNP environment. An assessment of required R&D for a Grade 91 vessel has been retained from the first revision of the R&D plan in Appendix B in somewhat less detail. Considerably more development is required for this steel compared to A 508/A 533 including additional irradiation testing for expected NGNP operating temperatures, high-temperature mechanical properties, and extensive studies of long-term microstructural stability.

J. K. Wright; R. N. Wright

2010-07-01

415

Evaluation of Hydrogen Embrittlement in Cr-Mo Pressure Vessel Steels. Topical Report No. 1.  

National Technical Information Service (NTIS)

Commercial 2 1/4 Cr-1 Mo low strength steel specimens were tested to measure their susceptibility to hydrogen embrittlement in an environment of H sub 2 S at 50 psig. The plane stress zones on the crack front in compact tension specimens and incubation ti...

B. J. Shaw E. W. Johnson

1980-01-01

416

Analysis of the Fluid-Structure Dynamic Interaction of Reactor Pressure Vessel Internals During Blowdown.  

National Technical Information Service (NTIS)

The loadings on reactor internal structures (in particular the core barrel) induced during a PWR-blowdown must not result in excessive stresses and strains. The deformations are strongly influenced by the coupling of fluid and structure dynamics and it is...

C. W. Hirt E. G. Schlechtendahl R. Krieg U. Schumann

1977-01-01

417

Effects of isometric handgrip training dose on resting blood pressure and resistance vessel endothelial function in normotensive women.  

PubMed

Isometric handgrip (IHG) training lowers resting blood pressure (BP) in both hypertensives and normotensives, yet the effect of training dose on the magnitude of reduction and the mechanisms associated with the hypotensive response are elusive. We investigated, in normotensive women, the effects of two different doses of IHG training on resting BP, and explored improved resistance vessel endothelial function and heart rate variability (HRV) as potential mechanisms of BP reduction. Resting BP, HRV, and resistance vessel endothelial function (venous strain-gauge plethysmography with reactive hyperemia) were assessed in 32 women before and after 4 and 8 weeks of 3×/week (n = 12) or 5×/week (n = 11) IHG training (four, 2-min unilateral contractions at 30 % maximal voluntary contraction), or 0×/week control (n = 9). IHG training decreased systolic BP in the 3×/week (94 ± 6 to 91 ± 6 to 88 ± 5 mmHg, pre- to mid- to post-training; P < 0.01) and 5×/week (97 ± 11 to 90 ± 9 to 91 ± 9 mmHg, P < 0.01) groups, concomitant with increased forearm reactive hyperemic blood flow (26 ± 7 to 30 ± 8 to 36 ± 9 mL/min/100 mL tissue, P < 0.01; and 26 ± 7 to 29 ± 7 to 38 ± 13 mL/min/100 mL tissue, P < 0.01, respectively), yet both remained unchanged in the control group. No changes were observed in diastolic BP, mean arterial BP, or any indices of HRV in any group (all P > 0.05). In conclusion, IHG training lowers resting systolic BP and improves resistance vessel endothelial function independent of training dose in normotensive women. PMID:23588257

Badrov, Mark B; Bartol, Cassandra L; DiBartolomeo, Matthew A; Millar, Philip J; McNevin, Nancy H; McGowan, Cheri L

2013-04-16

418

Expert system for process planning of pressure vessel fabrication by deep drawing and ironing  

Microsoft Academic Search

The fiber reinforced composite material is widely used in the multi-industrial field where the weight reduction of the infrastructure is demanded because of their high specific modulus and specific strength. It has two main merits which are to cut down energy by reducing weight and to prevent explosive damage proceeding to the sudden bursting which is generated by the pressure

C. H. Kim; J. H. Park; J. C. Choi

2004-01-01

419

Strength and life of pressure vessels subjected to impacts and thermomechanical GFRP loading  

Microsoft Academic Search

Non-insulated GRFP (Glass Fiber Reinforced Plastics) pipes were experimentally investigated. Particular consideration was given to the effects of short term thermal overloads and impact damage. It was shown that for a matrix with a long term specified service temperature of less than 140 C and starting from 140 C at 10 bar pressure up to 200 C and 30 bar

Pekka H. Pankakoski; Tero Uuttu; Pentti Kauppinen; Matti Sarkimo; Pertti Auerkari

1992-01-01

420

EXPERIMENTS ON MELT DISPERSION WITH LATERAL FAILURE IN THE BOTTOM HEAD OF THE PRESSURE VESSEL  

Microsoft Academic Search

Melt dispersion experiments with lateral failure in the bottom head were carried out in a 1:18 scaled annular cavity design under low pressure conditions. Water and a bis- mut-alloy were used as melt simulant material and nitrogen as driving gas. With lat- eral breaches the liquid height in the lower head relative to the upper and lower edge of the

L. MEYER; M. GARGALLO

421

Low-alloy steels for thick-walled pressure vessels. Summary report, February 1, 1980-January 31, 1982  

SciTech Connect

This program aimed to modify existing commercial pressure vessel steels to provide strong, tough, creep resistant materials, with low hydrogen attack and temper embrittlement susceptibilities, which can also be field-fabricated into thick-section vessels for coal conversion systems. Emphasis was placed on determining the effects of Mn, Ni and Cr on the creep rupture and hydrogen attack susceptibilities of Cr-Mo steels. Hydrogen attack studies were also carried out on A533B and model alloy systems to investigate the role of alloy carbides in promoting resistance to hydrogen damage. Creep rupture fracture times were determined at 500, 560 and 600/sup 0/C for periods up to 2000 hours. The effects of cooling rate from the austenitizing temperature and tempering response on the microstructure of 3Cr-1Mo-1Mn-1Ni steel were studied. The carbide structures in all the alloy modifications were carefully characterized. Data were collected from preliminary weld bead-on-plate tests of A387 and temper embrittlement studies of A543 with mischmetal addition. The unloading compliance test technique for J/sub Ic/ measurements was completed for A533B specimens but shortage of material prevented testing of A387. The mechanical property, elevated temperature creep and hydrogen attack data suggested that addition of 0.75 Cr + 0.5 Mn + 1Ni was beneficial in reducing susceptibility to hydrogen damage but was detrimental to creep rupture properties. 44 figures, 14 tables.

Todd, J.A.; Chung, D.W.; Parker, E.R.

1982-01-01

422

Preliminary assessment of the effects of biaxial loading on reactor pressure vessel structural-integrity-assessment technology  

SciTech Connect

Effects of biaxial loading on shallow-flaw fracture toughness were studied to determine potential impact on structural integrity assessment of a reactor pressure vessel (RPV) under pressurized thermal shock (PTS) transient loading and pressure-temperature (PT) loading produced by reactor heatup and cooldown transients. Biaxial shallow-flaw fracture-toughness tests results were also used to determine the parameter controlling fracture in the transition temperature range, and to develop a related dual-parameter fracture-toughness correlation. Shallow-flaw and biaxial loading effects were found to reduce the conditional probability of crack initiation by a factor of nine when the shallow-flaw fracture-toughness K{sub Jc} data set, with biaxial-loading effects adjustments, was substituted in place of ASME Code K{sub Ic} data set in PTS analyses. Biaxial loading was found to reduce the shallow-flaw fracture toughness of RPV steel such that the lower-bound curve was located between ASME K{sub Ic} and K{sub IR} curves. This is relevant to future development of P-T curve analysis procedures. Fracture in shallow-flaw biaxial samples tested in the lower transition temperature range was shown to be strain controlled. A strain-based dual-parameter fracture-toughness correlation was developed and shown to be capable of predicting the effect of crack-tip constraint on fracture toughness for strain-controlled fracture.

Pennell, W.E.; Bass, B.R.; Bryson, J.W.; Dickson, T.L.; McAfee, W.J.; Merkle, J.G.

1996-04-01

423

Evaluation of hydrogen embrittlement in Cr-Mo pressure vessel steels. Topical report No. 1  

SciTech Connect

Commercial 2-1/4 Cr-1 Mo low strength steel specimens have been tested to measure their susceptibility to hydrogen embrittlement in an environment of H/sub 2/S at 50 psig. It was found that two factors, viz. (i) the plane stress zones on the crack front in compact tension specimens and (ii) incubation time effects, seriously confounded measurements on these steels when tested by conventional rising load experiments. Because of the incubation time effect, K/sub or/ (the stress intensity at which cracking starts in a rising load test) is a loading rate dependent variable and is usually significantly greater than the arrest stress intensity, K/sub arr/ in a bolt loaded test. K/sub arr/ must therefore be used as a measure of hydrogen resistance. The incubation time has been significantly reduced by cyclicly loading in the environment to initiate the crack and K/sub arr/ has been measured by holding the specimen in constant displacement immediately after crack initiation. The plane stress problem has been eliminated by deeply side grooving the compact tension (CT) specimens. As an example of the importance of these effects a 3T CT smooth sided specimen was compared with a side grooved 2T CT specimen of the same steel. Whereas the K/sub or/ value for the smooth 3T was approximately 150 ksi in/sup 1/2/ the K/sub arr/ value for the side notched 2T was approximately 20 ksi in/sup 1/2/. A study of the effect of strength level is included.

Shaw, B.J.; Johnson, E.W.

1980-08-24

424

Failure of a welded pressure vessel due to creep: damage initiation, evolution and reheat cracking  

Microsoft Academic Search

Continuum damage mechanics (CDM)-based constitutive equations are reviewed and presented for austenitic AISI 316H stainless steels, which undergo creep deformation and damage at 550°C. Two multi-axial stress rupture functions\\/criteria have been utilised. Equations and the finite element computer code, DAMAGE XX, were used to carry out CDM studies of the weldment in an axi-symmetric equivalent of the flank section of

F. Vakili-Tahami; Hayhurst

2007-01-01

425

Thermographic detection of fatigue damage of pressure vessel steels at 1,000 Hz and 20 Hz  

SciTech Connect

Fatigue behavior is strongly affected by the environment, materials, and loading conditions. The process of fatigue can be categorized into three stages: crack initiation, growth, and final fracture. Nondestruction evaluation (NDE) of fatigue damage is of critical importance for life assessments and structural integrity evaluations. Several NDE methods, including ultrasonics, acoustic emission, and thermography, have been used to monitor fatigue damage. However, relatively little work has been conducted to assess fatigue characteristics using thermographic infrared techniques. In this paper, a thermographic infrared imaging system was used to detect the heat conditions of fatigued pressure vessel steels at 1,000 Hz and 20 Hz. Moreover, the fatigue behavior has been investigated at 1,000 Hz using an advanced electrohydraulic machine.

Liaw, P.K.; Wang, H.; Jiang, L.; Yang, B.; Huang, J.Y.; Kuo, R.C.; Huang, J.G.

2000-01-31

426

46 CFR 54.30-10 - Method of performing mechanical stress relief.  

Code of Federal Regulations, 2010 CFR

...false Method of performing mechanical stress relief. 54.30-10 Section 54...ENGINEERING PRESSURE VESSELS Mechanical Stress Relief § 54.30-10 Method of performing mechanical stress relief. (a) The mechanical...

2009-10-01

427

46 CFR 54.30-10 - Method of performing mechanical stress relief.  

Code of Federal Regulations, 2010 CFR

...false Method of performing mechanical stress relief. 54.30-10 Section 54...ENGINEERING PRESSURE VESSELS Mechanical Stress Relief § 54.30-10 Method of performing mechanical stress relief. (a) The mechanical...

2010-10-01

428

Uniaxial stress component in tungsten carbide anvil high-pressure X-ray cameras  

Microsoft Academic Search

The tungsten carbide opposed anvil cameras have been used extensively in high-pressure X-ray diffraction studies. The powdered sample is placed in a fine hole at the center of a boron or boron-epoxy disk which acts as a pressure vessel. The sample is pressurized by pressing the boron (boron-epoxy) disk between two tungsten carbide anvils. The X-ray beam passes through the

A. K. Singh; G. C. Kennedy

1974-01-01

429

A numerical method for the computation of the effects of an air vessel on the pressure surges in pumping systems with air entrainment  

NASA Astrophysics Data System (ADS)

This paper describes an improved numerical method and computational procedure for the implementation of typical air vessel responses and their influence on the pressure transient for unsteady flow in a pipeline system with air entrainment. The proposed numerical method and computational procedure is without the necessity of an excessive iterative procedure as required previously by the conventional approach. The effects of air in the transient fluid system with the air vessel were then studied through the improved numerical computational method. Free and dissolved gases in the transported fluid, and cavitation at vapour pressure, are included.

Lee, T. S.

1998-09-01

430

Fractographic and Microstructural Analysis of Stress Corrosion Cracking of A533 Grade B Class 1 Plate and A508 Class 2 Forging in Pressurized Reactor-Grade Water at 93 C.  

National Technical Information Service (NTIS)

Stress corrosion cracking (SCC) studies were conducted in two commonly used pressure vessel steels: A533 Grade B Class 1 (A533-B-1) plate and an equivalent A508 Class 2 (A508-2) forging. The purpose of these studies was to determine the response of the ma...

V. Provenzano K. Torronen D. Sturm W. H. Cullen

1980-01-01

431

Fractographic and Microstructural Analysis of Stress Corrosion Cracking of A533 Grade B Class 1 Plate and A508 Class 2 Forging in Pressurized Reactor-Grade Water at 93 degrees C.  

National Technical Information Service (NTIS)

Stress corrosion cracking (SCC) studies were conducted in two commonly used pressure vessel steels: A533 Grade B Class 1 (A533-B-1) plate and an equivalent A508 Class 2 (A508-2) forging. The purpose of these studies was to determine the response of the ma...

V. Provenzano K. Torronen D. Sturm W. H. Cullen

1980-01-01

432

Development of a nuclear technique for monitoring water levels in pressurized vessels  

SciTech Connect

A new technique for monitoring water levels in pressurized stainless steel cylinders was developed. It is based on differences in attenuation coefficients of water and air for Cs137 (662 keV) gamma rays. Experimentally observed gamma ray counting rates with and without water in model reservoir cylinder were compared with corresponding calculated values for two different gamma ray detection theshold energies. Calculated values include the effects of multiple scattering and attendant gamma ray energy reductions. The agreement between the measured and calculated values is reasonably good. Computer programs for calculating angular and spectral distributions of scattered radition in various media are included.

Singh, J.J.; Davis, W.T.

1983-09-01

433

Changes in magnetic parameters of neutron irradiated SA 508 Cl. 3 reactor pressure vessel forging and weld surveillance specimens  

NASA Astrophysics Data System (ADS)

Irradiation-induced changes in the magnetic parameters and mechanical properties were measured and compared to explore possible correlations for reactor pressure vessel (RPV) forging and weld surveillance Charpy specimens which were irradiated to the neutron fluence of 2.3×1019 n/cm2 (E>1.0 MeV) in a typical pressurized water reactor environment at 290 °C. For mechanical property parameters, Vickers microhardness, tensile and Charpy impact tests were performed and saturation magnetization (Ms), remanence (Mr), coercivity (Hc), and Barkhausen noise amplitude (BNA) were measured for magnetic parameters for both unirradiated and irradiated specimens, respectively. Results of mechanical property measurements showed an increase in yield and tensile strength, Vickers microhardness, 30 ft. lb indexed RTNDT and a decrease in Charpy upper-shelf energy irrespective of forging and weld metals. Hysteresis loops appeared to turn clockwise, resulting in an increase in Hc, and BNA appeared to decrease after irradiation. Both magnetic parameters showed viable correlations to the changes in mechanical parameters (Vickers microhardness, Charpy upper shelf energy) due to irradiation. Even limited, the present study seems to show additional possibilities for the application of this magnetic method in monitoring the mechanical parameter changes due to neutron irradiation.

Chi, Se-Hwan; Chang, Kee-Ok; Hong, Jun-Hwa; Kuk, Il-Hiun; Kim, Chong-Oh

1999-04-01

434

Stress Singularities in a Model of a Wood Disk under Sinusoidal Pressure  

Microsoft Academic Search

A thin, solid, circular wood disk, cut from the transverse plane of a tree stem, can be modeled as a cylindrically orthotropic elastic material. It is known that a stress singularity can occur at the center of a cylindrically orthotropic disk subjected to uniform pressure. If a solid cylindrically orthotropic disk is subjected to sinusoidal pressure distributions, then other stress

Jay A. Johnson; John C. Hermanson; Steven M. Cramer

2005-01-01

435

Hydraulic fracture reopening pressure and the estimation of maximum horizontal stress  

Microsoft Academic Search

In hydrofracture stress measurements, the magnitude of the maximum horizontal stress, SH, is commonly estimated from the borehole pressure required to reopen an induced axial crack. Examination of the processes which govern the borehole pressure history recorded during the reopening cycle of such tests indicates two sources of error in the estimates of SH derived using the conventional method proposed

T. Ito; K. Evans; K. Kawai; K. Hayashi

1999-01-01

436

Abnormally High Fluid Pressures and Associated Porosities and Stress Regimes in Sedimentary Basins  

Microsoft Academic Search

The relationships between overpressures and porosity and overpressures and stress regime are found to differ significantly according to the geological setting and overpressure generating mechanism. These factors must be taken into account in pore pressure prediction techniques and in correlations between pore pressure and minimum horizontal stress. Two examples from overpressured Canadian basins are presented to illustrate the above.

N. A. Yassir; J. S. Bell

1996-01-01

437

Tissue Engineering of Ovine Aortic Blood Vessel Substitutes Using Applied Shear Stress and Enzymatically Derived Vascular Smooth Muscle Cells  

Microsoft Academic Search

Compared to native blood vessels, all clinically available blood vessel substitutes perform suboptimally. Numerous approaches to tissue engineer (TE) blood vessels have been pursued using different scaffold materials, cell types, and culture conditions. Several limitations however remain to be overcome prior to the potential application in the arterial system. This study aimed at tissue engineering viable ovine blood vessels suitable

F. Opitz; K. Schenke-Layland; W. Richter; D. P. Martin; I. Degenkolbe; Th. Wahlers; U. A. Stock

2004-01-01

438

Apparatus for the pneumatic injection of pulverulent materials into a pressurized vessel, and its application to the injection of powered coal into a shaft furnace  

SciTech Connect

This patent describes an apparatus for the pneumatic injection of pulverulent materials into a pressurized vessel, comprising a storage silo, a series of metering means for extracting the pulverulent material from the distribution silo, pneumatic conveying pipes connecting each of the metering means to the pressurized vessel, and also means for the automatic transfer of the pulverulent material from the storage silo. It includes: two intermediate silos, each intermediate silo is connected by first automatic valve means upstream to the storage silo and by second automatic valve means downstream to the distribution silo; pressurizing circuit means connecting a source of inert gas under pressure through third automatic valve means to each of the intermediate silos; and wherein the two intermediate silos are alternately connected to the storage silo and to the distribution silo to enable substantially continuous transfer of pulverulent material from the storage silo to the distribution silo.

Ulveling, L.; Schmit, L.; Legille, E.

1987-10-27

439

Composition and chemistry of particulates from the Tidd Clean Coal Demonstration Plant pressurized fluidized bed combustor, cyclone, and filter vessel  

SciTech Connect

In a Pressurized Fluidized Bed Combustion (PFBC)/cyclone/filter system ground coal and sorbent are injected as pastes into the PFBC bed; the hot gases and entrained fine particles of ash and calcined or reacted sorbent are passed through a cyclone (which removes the larger entrained particles); and the very-fine particles that remain are then filtered out, so that the cleaned hot gas can be sent through a non-ruggedized hot-gas turbine. The 70 MWe Tidd PFBC Demonstration Plant in Brilliant, Ohio was completed in late 1990. The initial design utilized seven strings of primary and secondary cyclones to remove 98% of the particulate matter. However, the Plant also included a pressurized filter vessel, placed between the primary and secondary cyclones of one of the seven strings. Coal and dolomitic limestone (i.e, SO{sub 2} sorbent) of various nominal sizes ranging from 12 to 18 mesh were injected into the combustor operating at about 10 atm pressure and 925{degree}C. The cyclone removed elutriated particles larger than about 0.025 mm, and particles larger than ca. 0.0005 mm were filtered at about 750{degree}C by ceramic candle filters. Thus, the chemical reaction times and temperatures, masses of material, particle-size distributions, and chemical compositions were substantially different for particulates removed from the bed drain, the cyclone drain, and the filter unit. Accordingly, we have measured the particle-size distributions and concentrations of calcium, magnesium, sulfur, silicon, and aluminum for material taken from the three units, and also determined the chemical formulas and predominant crystalline forms of the calcium and magnesium sulfate compounds formed. The latter information is particularly novel for the filter-cake material, from which we isolated the ``new`` compound Mg{sub 2}Ca(SO{sub 4}){sub 3}.

Smith, D.H.; Grimm, U.; Haddad, G.

1995-12-31

440

The assessment of reactor pressure vessel defects allowing for crack tip constraint and its effect on the calculation of the onset of the upper shelf  

Microsoft Academic Search

The paper shows how a specialised application of the R6 method could be used to calculate a pressure–temperature failure envelope for postulated defects in a reactor pressure vessel (RPV), making due allowance for the distribution of constraint around the crack front. As such, the technique provides a means of estimating a defect-specific onset of upper shelf temperature (OUST).A material's constraint-based

D. W. Beardsmore; A. R. Dowling; D. P. G. Lidbury; A. H. Sherry

2003-01-01

441

Sympathoexcitation by Oxidative Stress in the Brain Mediates Arterial Pressure Elevation in Obesity-Induced Hypertension  

Microsoft Academic Search

Background—Obesity is one of the major risk factors for cardiovascular disease and is often associated with increased oxidative stress and sympathoexcitation. We have already suggested that increased oxidative stress in the brain modulates the sympathetic regulation of arterial pressure in salt-sensitive hypertension, which is often associated with obesity. The present study was performed to determine whether oxidative stress could mediate

Ai Nagae; Megumi Fujita; Hiroo Kawarazaki; Hiromitsu Matsui; Katsuyuki Ando; Toshiro Fujita

2010-01-01

442

The NRL-EPRI research program (rp886-2) evaluation and prediction of neutron embrittlement in reactor pressure vessel materials. Annual progress report for CY 1977  

Microsoft Academic Search

Nuclear reactor pressure vessel materials are subject to progressive reductions in fracture resistance in service due to neutron irradiation. Current technology is insufficient to quantitatively predict radiation embrittlement for all typical materials and their metallurgical variations for neutron fluences of interest. Another needed refinement to radiation effects technology involves the establishment of a relationship between apparent notch ductility and fracture

Hawthorne

1978-01-01

443

A theoretical model for determination of fracture toughness of reactor pressure vessel steels in the transition region from automated ball indentation test  

Microsoft Academic Search

A theoretical model is proposed to estimate the fracture toughness of ferritic steels in the transition region from ball indentation test data. The key concept of the model is that the indentation energy to a critical load is related to the fracture energy of the material. By applying the new model, the fracture parameters of reactor pressure vessel steel base

Thak Sang Byun; Jin Weon Kim; Jun Hwa Hong

1998-01-01

444

An experimental study of elastic-plastic fracture on the special shape plate specimen with high strain gradient simulating pressure vessel nozzles  

Microsoft Academic Search

The paper presents a shape plate specimen with high strain gradient fields which are similar to those at pressure vessels nozzles. On the specimens, experimental J parameter was obtained by means of the multiple specimen technique; the CTOD δ of three definitions was measured with the microphotography technique; the fracture criteria of the crack initiation were examined at the same

Y. Zhao; Z. Z. Li; G. X. Y. P. Zheng; G. L. Cheng; Z. B. Huang

1989-01-01

445

Effects of Prolonged Hemorrhagic Hypotensive Stress on Catecholamine Concentration of Mesenteric Blood Vessels  

Microsoft Academic Search

Norepinephrine (NE) and epinephrine (E) concentrations were determined fluorometrically as an index of functional adrenergic innervation in small mesenteric arteries, veins, and superior mesenteric arteries of dogs and rats subjected to a period of prolonged hemorrhage at a constant mean arterial pressure of 35 mm Hg. In nonhemorrhaged animals, highest catecholamine concentrations were found in the small principal arteries, next

J. H. Lombard; D. J. Loegering; W. J. Stekiel

1977-01-01

446

Heat-stress-induced changes in central venous pressure do not explain interindividual differences in orthostatic tolerance during heat stress.  

PubMed

The extent to which heat stress compromises blood pressure control is variable among individuals, with some individuals becoming very intolerant to a hypotensive challenge, such as lower body negative pressure (LBNP) while heat stressed, while others are relatively tolerant. Heat stress itself reduces indexes of ventricular filling pressure, including central venous pressure, which may be reflective of reductions in tolerance in this thermal condition. This study tested the hypothesis that the magnitude of the reduction in central venous pressure in response to heat stress alone is related to the subsequent decrement in LBNP tolerance. In 19 subjects, central hypovolemia was imposed via LBNP to presyncope in both normothermic and heat-stress conditions. Tolerance to LBNP was quantified using a cumulative stress index (CSI), and the difference between normothermic CSI and heat-stress CSI was calculated for each individual. The eight individuals with the greatest CSI difference between normothermic and heat-stress tolerances (LargeDif), and the eight individuals with the smallest CSI difference (SmallDif), were grouped together. By design, the difference in CSI between thermal conditions was greater in the LargeDif group (969 vs. 382 mmHg × min; P < 0.001). Despite this profound difference in the effect of heat stress in decreasing LBNP tolerance between groups, coupled with no difference in the rise in core body temperatures to the heat stress (LargeDif, 1.4 ± 0.1°C vs. SmallDif, 1.4 ± 0.1°C; interaction P = 0.89), the reduction in central venous pressure during heat stress alone was similar between groups (LargeDif: 5.7 ± 1.9 mmHg vs. SmallDif: 5.2 ± 2.0 mmHg; interaction P = 0.85). Contrary to the proposed hypothesis, differences in blood pressure control during LBNP are not related to differences in the magnitude of the heat-stress-induced reductions in central venous pressure. PMID:21415173

Brothers, R Matthew; Keller, David M; Wingo, Jonathan E; Ganio, Matthew S; Crandall, Craig G

2011-03-17

447

Fractographic and microstructural analysis of stress corrosion cracking of A533 Grade B Class 1 plate and A508 Class 2 forging in pressurized reactor-grade water at 93 degrees C  

Microsoft Academic Search

Stress corrosion cracking (SCC) studies were conducted in two commonly used pressure vessel steels: A533 Grade B Class 1 (A533-B-1) plate and an equivalent A508 Class 2 (A508-2) forging. The purpose of these studies was to determine the response of the materials in simulated pressurized water reactor environment. Round tensile specimens, 32 mm (1.25 in.) along the gage section and

V. Provenzano; K. Torronen; D. Sturm; W. H. Cullen

1980-01-01

448

Crack extension caused by internal gas pressure compared with extension caused by tensile stress  

Microsoft Academic Search

Explosive loading in borehole configurations has been investigated to assess the relative importance of internal gas pressurization and stress-wave-induced circumferential tensions for extending radial cracks originating at the borehole walls. Simple calculations of an extending crack (with and without confining pressure) were performed to estimate an upper bound on crack length resulting solely from internal pressurization for comparison with the

Stuart McHugh

1983-01-01

449

Induction of Oxidative Stress by High Hydrostatic Pressure in Escherichia coli  

PubMed Central

Using leaderless alkaline phosphatase as a probe, it was demonstrated that pressure treatment induces endogenous intracellular oxidative stress in Escherichia coli MG1655. In stationary-phase cells, this oxidative stress increased with the applied pressure at least up to 400 MPa, which is well beyond the pressure at which the cells started to become inactivated (200 MPa). In exponential-phase cells, in contrast, oxidative stress increased with pressure treatment up to 150 MPa and then decreased again, together with the cell counts. Anaerobic incubation after pressure treatment significantly supported the recovery of MG1655, while mutants with increased intrinsic sensitivity toward oxidative stress (katE, katF, oxyR, sodAB, and soxS) were found to be more pressure sensitive than wild-type MG1655. Furthermore, mild pressure treatment strongly sensitized E. coli toward t-butylhydroperoxide and the superoxide generator plumbagin. Finally, previously described pressure-resistant mutants of E. coli MG1655 displayed enhanced resistance toward plumbagin. In one of these mutants, the induction of endogenous oxidative stress upon high hydrostatic pressure treatment was also investigated and found to be much lower than in MG1655. These results suggest that, at least under some conditions, the inactivation of E. coli by high hydrostatic pressure treatment is the consequence of a suicide mechanism involving the induction of an endogenous oxidative burst.

Aertsen, Abram; De Spiegeleer, Philipp; Vanoirbeek, Kristof; Lavilla, Maria; Michiels, Chris W.

2005-01-01

450

Damage evaluation and analysis of composite pressure vessels using fiber Bragg gratings to determine structural health  

NASA Astrophysics Data System (ADS)

The application of MEMS and nanotechnology (MNT) to the field of structural health monitoring (SHM) is a fairly recent development. The recent change in this focus for MNT has been driven by the need to expand the applications for much of the technologies that were developed in the late 1990s. In addition, many companies desire to expand beyond their target high volume market segments of automotive, wireless communications, and computer peripherals, since these market segments were not as lucrative as first predicted. Most of the aerospace structural health monitoring developmental activity has been sponsored by agencies of the U.S. Government, which serves to pace the examination of these newer technologies to some degree. With that said, efforts are underway by companies such as Acellent Technologies and Blue Road Research to explore various MNT structural health monitoring approaches. The MNT under test include embedded piezoelectric sensors, MEMS accelerometers, time domain region sensors, and topical and embedded single and multi-axis fiber optic Bragg grating sensors. The promise of MNT for the SHM market segment is very enticing. The many wireless communication developments and miniaturization developments of the past five years is very attractive to the SHM community, especially those that are able to reduce the cost and complexity of integration. The main challenge for the community is one of selective integration. That is, certain pieces may be appropriate for SHM systems and certain pieces may not be. The better companies will chose wisely and put forth an approach that can be seamlessly integrated into the larger structure. For over a decade, Blue Road Research has been developing technologies aimed at structural health monitoring of both composite and non-composite parts, through the use of single and multiaxis fiber optic Bragg grating sensors. These sensors are 80 to 120 microns in diameter making them smaller than the diameter of a human hair. Multiaxis fiber optic sensors are able to measure pressure, temperature, axial and transverse strain, chemical properties, corrosion, as well as transverse strain gradients. This technology is easily embedded in between the various layers of the composite structure, during manufacture, without compromising the structural integrity, in order to verify manufacturing parameters during the cure cycle and well as monitor the on-going condition of the composite structure throughout its life time. This paper reviews some of the technical work that has been accomplished during the past two years; specifically the embedding of fiber optic sensors into various composite structures in order to be able to conduct in situ non-destructive evaluation of the curing process and the service life of the component. The fiber optic technology has been developed to the point that it is at a TRL of 6.

Ortyl, Nicholas E.

2005-11-01

451

Effect of stress management on blood pressure in mild primary hypertension.  

PubMed Central

OBJECTIVE--To establish whether stress management had a larger effect than a control treatment on resting blood pressure, ambulatory blood pressure, and left ventricular mass. DESIGN--A 12 week baseline period of habituation to measurement of blood pressure was followed by randomisation to either stress management or mild exercise for six months and follow up six months later. SETTING--General practice, district general hospital, and medical school. PATIENTS--Of the 184 patients aged under 60 with mild primary hypertension who entered the baseline habituation period, 88 were excluded because they failed to meet the entry criteria or they withdrew from the study. The remaining 46 men and 50 women underwent treatment. INTERVENTIONS--10 clinical sessions and daily practice at home of either stress management based on relaxation or non-aerobic stretching exercises. Mildly stressful 15 minute interviews before and after treatment. MAIN OUTCOME MEASURES--Diastolic and systolic blood pressure in the clinic and during 12 hours of ambulatory recording, and left ventricular mass measured by echocardiography. RESULTS--The patients' blood pressure fell during habituation (systolic pressure from 152 mmHg to 140 mmHg, diastolic pressure from 98 to 93 mm Hg), but neither resting nor ambulatory blood pressure was changed by the treatments. Left ventricular mass was also unchanged. Blood pressure rose during the stressful interview, but this rise was reduced by stress management (systolic pressure rose by 7.4 mmHg before treatment and by 3.7 mmHg after treatment). CONCLUSION--Stress management of a type advocated for treating mild primary hypertension is ineffective in lowering blood pressure in patients who are well habituated to measuring blood pressure.

Johnston, D W; Gold, A; Kentish, J; Smith, D; Vallance, P; Shah, D; Leach, G; Robinson, B

1993-01-01

452

The mechanisms of immune suppression by high-pressure stress in mice.  

PubMed

The effects of high-pressure stress on the induction of anti-sheep red blood cells (SRBC) and of plaque-forming cells (PFC), and on thymus weight, were studied in BALB/c mice in-vivo and in-vitro. The efficacy of high-pressure stress in suppressing PFC and thymic involution was maximum when the stress was applied 1 h day(-1) for 2 days before immunization with SRBC. Both effects were blocked by administration of indomethacin, atropine, naloxone or phentolamine before the first application of stress, whereas hexamethonium and propranolol had no such effect. Hexamethonium, naloxone and propranolol administered before the second application of high-pressure stress blocked both effects. Prostaglandin and acetylcholine given 24 h before application of high-pressure stress caused a marked reduction in PFC count, but not in thymus weight. The reduced PFC count caused by acetylcholine was blocked by pretreatment with indomethacin. When adrenaline was injected 24 h after application of high-pressure stress a marked reduction in PFC was observed, but without thymic involution. When adrenaline was injected 24 h after prostaglandin injection the PFC count was also markedly reduced, but not thymus weight. The decrease in PFC caused by two exposures to stress or one exposure to stress plus injection of adrenaline was blocked by diethylcarbamazine before the second exposure to stress or the injection of adrenaline. In addition, normal spleen cells, were induced as suppressor cells when incubated with the serum of stressed mice, but not when supplemented with anti-leukotriene C4, D4 antibody. These data suggest that mice fall into a pre-stress condition via the release of prostaglandin after the first stress, and then immunosuppression is induced in these prestressed mice via the release of leukotriene C4, D4, caused by the activation of the autonomic nervous system by the second exposure to stress. PMID:10678494

Fujiwara, R; Shibata, H; Komori, T; Yokoyama, M M; Okazaki, Y; Ohmori, M

1999-12-01

453

On the use of expert judgments to estimate the pressure increment in the Sequoyah containment at vessel breach  

SciTech Connect

The use of expert judgments in probabilistic risk assessments has become common. Simple aggregation methods have often been used with the result that expert biases and interexpert dependence are often neglected. Sophisticated theoretical models for the use of expert opinions have been proposed that offer ways of incorporating expert biases and dependence, but they have not found wide acceptance because of the difficulty and rigor of these methods. Practical guidance on the use of the versatile Bayesian expert judgment aggregation model is provided. In particular, the case study of pressure increment due to vessel breach in the Sequoyah nuclear power plant is chosen to illustrate how phenomenological uncertainty can be addressed by using the Bayesian aggregation model. The results indicate that the Bayesian aggregation model is a suitable candidate model for aggregating expert judgments, especially if there is phenomenological uncertainty. Phenomenological uncertainty can be represented through the dependence parameter of the Bayesian model. This is because the sharing of assumptions by the experts tends to introduce dependence between the experts. The extent of commonality in the experts' beliefs can be characterized by assessing their interdependence. The results indicate that uncertainty is possibly underestimated by ignoring dependence.

Chhibber, S.; Apostolakis, G.E.; Okrent, D. (Univ. of California, Los Angeles, CA (United States). School of Engineering and Applied Science)

1994-01-01

454

[Self-regulation of xylem pressure in barley roots under salt stress].  

PubMed

Xylem pressure in young barley roots, measured in vivo with a xylem pressure probe, showed constant, irregular fluctuations both under altered or unchanged environmental conditions. When mild salt stress was applied or when the stress was eliminated, xylem pressure in barley roots exhibited intense self-regulation or relaxation, leading to a consequence that the difference of xylem pressure before and after the salt stress was greatly narrowed and the barley plants could maintain a relatively stable xylem pressure. The process of regulation or relaxation of xylem pressure in barley roots lasted about one hour or more before a relatively stable state was achieved. The self-regulation or relaxation of xylem pressure was not dependent on the initial status of the xylem pressure. Both the fluctuation and the self-regulation of xylem pressure in plant roots could exert substantial uncertainties on the conventional measurements of water potential and the radial reflection coefficient of barley roots, especially when the pressure bomb (Schollander bomb) or root