Thickness Of Vessel Research Articles

VVER-440 and VVER-1000 Reactor Dosimetry Benchmark —BUGLE-96 Versus ALPAN VII.0

Abstract Analytical results of the vodo-vodyanoi energetichesky reactor- (VVER-) 440 and VVER-1000 reactor dosimetry benchmarks developed from engineering mockups at the Nuclear Research Institute Rez LR-0 reactor are discussed. These benchmarks provide accurate determination of radiation field parameters in the vicinity and over the thickness of the reactor pressure vessel. Measurements are compared to calculated results with two sets of tools: TORT discrete ordinates code and BUGLE-96 cross-section library versus the newly Westinghouse-developed RAPTOR-M3G and ALPAN VII.0. The parallel code RAPTOR-M3G enables detailed neutron distributions in energy and space in reduced computational time. ALPAN VII.0 cross-section library is based on ENDF/B-VII.0 and is designed for reactor dosimetry applications. It uses a unique broad group structure to enhance resolution in thermal-neutron-energy range compared to other analogous libraries. The comparison of fast neutron (E > 0.5 MeV) results shows good agreement (within 10 %) between BUGLE-96 and ALPAN VII.0 libraries. Furthermore, the results compare well with analogous results of participants of the REDOS program (2005). Finally, the analytical results for fast neutrons agree within 15 % with the measurements, for most locations in all three mockups. In general, however, the analytical results underestimate the attenuation through the reactor pressure vessel thickness compared to the measurements.

Use of corrosion-resistant steels and alloys in sulfuric acid media

Within the chemical industry, and also in some other branches, there is extensive use of sulfuric acid solutions of different concentration and corrosiveness, containing metal ions of varied valency (Cu2+, Fe3+, Ni2+, Cr3+, etc.), which appear in a medium, for example, as a result of equipment corrosion, etc. In sulfuric acid media, corrosion can be uniform or local, i.e., pitting, spot corrosion, intercrystalline corrosion (ICC). Whereas uniform corrosion develops as a gradual reduction in the thickness of an original vessel, equipment, and machine component elements, whose corrosion rate may be calculated previously from existing data for the corrosion resistance of structural materials in specific production media, it is almost impossible to predict ICC development, and therefore in many cases it leads to sudden structural breakdown. In order to predict corrosion, it is recommended to use for article manufacture corrosion-resistant steels and alloys with alloying providing in sulfuric acid solutions resistance to uniform and local corrosion with the required heat treatment and monitoring for ICC resistance.

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

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 longitudinal modulus, inside radius of composite layers, unsupported length and external pressure significantly affect the design results, whereas transversal modulus, Poisson’s ratio, shear modulus and winding angle have little effects. In order to validate the design results, a filament-wound composite pressure vessel is manufactured, and the buckling test is performed. It is observed that when the applied external hydrostatic pressure is a little more than the designed critical buckling pressure, the buckling and subsequent burst behaviours occur, which shows a good agreement between the experimental and analytical results.

Effect of wind loads on the stability of conical tanks

During the past few decades, a number of conical tanks have collapsed in various locations around the globe. Previous studies attributed the reason of collapse to inadequate thickness of the conical vessel especially at the bottom part. Most of the previous studies focused on studying the stability of conical tanks under the effect of only hydrostatic pressure. The current study focuses on studying the combined effect of wind loading and hydrostatic pressure on the stability of conical tanks. The study is conducted numerically, using a three-dimensional finite element model that is developed in-house. The critical imperfection shapes leading to minimum buckling capacity of conical shells under wind load alone, and under the combined effect of wind load and hydrostatic pressure, are determined. The study shows that a non-axisymmetric imperfection shape leads to minimum buckling capacity of empty conical tanks subjected to wind loads, while an axisymmetric distribution is noticed in the case of conical tanks under the combined effect of wind loads and hydrostatic pressure. In addition, the current study assesses the adequacy of an existing design procedure, which accounts for hydrostatic pressure, when the combination of hydrostatic pressure and wind load is considered.

Dome Thickness Prediction of Composite Pressure Vessels by a Cubic Spline Function and Finite Element Analysis

Nowadays, finite element analysis (FEA) plays an important role in the design of composite pressure vessel. The more accurate finite element models are created, the more precise results could be obtained. In order to create the accurate finite element model for composite pressure vessels, a cubic spline function was developed to predict the dome thickness basing on the principle of total volume preservation of all bands at dome section. In the paper, the dome thickness of an arbitrary composite pressure vessel was forecasted by the cubic spline function and compared with the existing methods and actual measured values. The results show that the cubic spline function is more realistic than the other methods. Then the FEA considering the dome thickness pre-calculated by various methods was performed and compared with experimental data. The results further indicate that the cubic spline function could provide a more accurate model, which is approaching the real case.

A new method for predicting dome thickness of composite pressure vessels

This research aims to establish a new method to predict the dome thickness of composite pressure vessels. A cubic spline function was presented to calculate the dome thickness. Using this cubic spline function, the dome thickness of an arbitrary composite pressure vessel was forecasted. The predictive results were compared with the existing methods and actual measured thickness. Then, the accuracy of this cubic spline function was discussed for predicting the dome thickness of composite pressure vessels with different polar radii and different fiber band width values. The results showed that dome thickness obtained from the cubic spline function could reflect the actual measured thickness well and it could provide an accurate model for the finite element analysis.

406 FBR炉容器へのLRFD適用に関する検討(OS4-2 LRFD法の展開)

This paper introduces an example of reliability evaluation for Fast Breeder Reactor (FBR) around sodium surface based on Load and Resistance Factor Design (LRFD) method. The reliability evaluation is conducted for some of failure modes due to seismic load and thermal load. Considered failure modes are buckling due to seismic load and ratcheting and creep fatigue due to thermal load. Relationship between design wall thickness of FBR reactor vessel and reliability index is calculated by the reliability evaluation applying advanced first-order second-moment method (AFOSM)

Proposal of a Mechanical Index for Arteries

Arteriosclerosis is such a phenomena hardening of arteries, with thickening and loss of elasticity. Previous indexes are included both geometric factor and mechanical factor as the radius, the wall thickness and mechanical properties of blood vessel. Furthermore, those indexes are formulated based on the static relationship between a pressure and a radial change. In this study, we suggested an evaluation index formulated by thin cylindrical shell theory estimated dynamic strain, and this index was independent of wall thickness and radius of arterial vessel. To confirm the validity of the evaluation index, we evaluated the parameters of viscosity and elasticity using the latex tube with different wall thickness of blood vessel model. We measured a radius of the latex tube and an inner pressure maintained a pulsatile pump in a mock circuit filled with the water. Estimating the parameters of viscosity and elasticity using these measurement values, we concluded that a proposal index was independent of the wall thickness and the radius of the arterial vessel.

Liquid Metal Free Surface Motion Submerged in an AC Magnetic Field

Free surface motion of a liquid metal submerged in an alternating magnetic field has been examined. A copper vessel filled with a liquid gallium is set in a coil for the imposition of the alternating magnetic field. The alternating magnetic field penetrates into a liquid gallium only from an upper free surface because thickness of the copper vessel is larger than the electromagnetic skin layer of copper. Time variation of displacement of the standing wave loop excited on the free surface is detected by a laser level sensor. The standing wave was suppressed not only by intensification of the magnetic field magnitude but also increase of the magnetic field frequency.

Validation of nuclear and radiation safety of a container for spent amb reactor fuel assemblies at the Beloyarskaya nuclear power plant

An approach is proposed for validating the nuclear and radiation safety of a container for spent fuel assemblies from AMB-100 and-200 reactors at the Beloyarskaya nuclear power plant. To validate the radiation safety, the characteristics of fuel assemblies and their classification according to the average fuel burnup in the casing, and the intensities of n and γ radiation in the casing are analyzed. Nuclear safety is validated on the basis of the concept of a “model” casing. This model makes it possible to obtain an upper estimate of the effective coefficient of neutron multiplication for all real casings with fuel assemblies. Calculations are used to determine the minimum necessary thickness of the vessel, bottom, and cover for 17-and 35-place casings. It is shown that no special neutron protection is needed. The container design to be developed meets the IAEA and OPBZ-83 safety standards.

Error estimation of geometrical data obtained by histomorphometry of oblique vessel sections: a computer model study

The errors of radius and wall thickness of a single vessel due to oblique sectioning in histomorphometry are expressed as a function of the circular shape factor (CSF) of the section's lumen, assuming cylindrical geometry and the absence of tissue deformation. Using computer model trees generated by constrained constructive optimization, mean errors are estimated for an ensemble of vessel segments. A geometrical exclusion criterion for segments cut too obliquely is defined on the basis of a CSF-cutoff value. It is shown that CSF-values ranging from 0.95 to 0.9 are reasonable choices for a cutoff and lead to mean errors of the same order of magnitude ( 9.6 % [ 9.3 % ] to 15.4 % [ 14.8 % ] for the radius [wall thickness]) as errors due to histological tissue processing.

The man-loading high-temperature superconducting maglev test vehicle

The first man-loading high-temperature superconducting (HTS) Maglev test vehicle in the world was successfully developed on Dec. 31, 2000 in the Applied Superconductivity Laboratory, Southwest Jiaotong University, China. Heretofore over 24 500 passengers took the vehicle, and it has been operating back and forth for about 400 km. The HTS Maglev vehicle provides inherent stability both in the vertical and lateral direction, so no control system is needed. The only control system is used for linear motor driving devices. The melt-textured YBaCuO bulk superconductors are fixed on the bottom of a liquid nitrogen vessel and cooled by liquid nitrogen. The bottom thickness of the rectangle liquid nitrogen vessel with its thin wall is only 3 mm. The onboard HTS Maglev module is placed over the guideway. The guideway consists of two parallel permanent magnetic tracks, whose concentrating magnetic field at 20 mm height above the surface is about 0.5 T. The levitation forces of 8 HTS Maglev modules were measured. The total levitation force of 8 onboard Maglev modules was 10431 N at the levitation gap of 10 mm, and 8486 N at the levitation gap of 15 mm, respectively. These results were measured on May 28, 2002.

Preparation of sheet polypyrrole with vertical anisotropy: A self-organized bending-beam actuator

In this paper, a method to prepare large anisotropic PPy films using a thin slab vessel consisting of PTFE films is proposed. Our recent studies show that polypyrrole (PPy) films grown in a slender pipe of poly(tetrafluoroethylene) (PTFE) have a considerable vertical anisotropy (anisotropy along thickness), and therefore is available as a self-organized bending-beam actuator. However, poor productivity is one of the main problems of this method. It has been found that the thickness of the slab vessel considerably affects the morphology of the resulted film. The obtained PPy films bend and revert during redox cycles, as PPy films grown in a slender PTFE pipe do.

Some issues by using the master curve concept

The master curve concept allows to quantify the variation of fracture toughness with the temperature throughout the ductile-to-brittle transition region. Limit curves of fracture toughness for defined failure probabilities and reference temperatures can be determined using this method. Thus, fracture mechanical values can be supplied for an integrity assessment of structural components. This paper presents the application of the master curve concept to the reference temperature determination over the thickness of the reactor pressure vessel (RPV) steel plate. It was shown that the master curve concept is applicable to the fracture mechanical characterisation of material with different microstructures using small test specimens. The influence of the materials homogeneity and the test temperature on the resulting reference temperature was investigated.

Anwendung des instrumentierten Kerbschlagbiegeversuchs zur Ermittlung von Referenztemperaturen nach dem Master-Curve-Konzept

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Evaluation of Nuclear Heat and Dose Rate for JT-60SU

Neutronics investigation has been made for the JT-60SU. Under the neutron production rate of l×l020n/s due to D-T operation, peak nuclear heating rate in a superconducting magnet (SCM) winding pack is 0.19 mW/cm2 at the inboard on the mid-plane, and that at the outboard near the NBI duct is 0.27 mW/cm3. These values satisfy the design limit of 0.2 mW/cm3 in inboard SCM winding pack and that of 1 mW/cm3 in the outboard SCM near the duct, respectively. The dose rate in one month after shutdown of 8000 s operation in the cryostat near the NBI duct is obtained ~10 μSv/h. The dose rate in the cryostat in one month after shutdown satisfies the design target of 20 μ Sv/h. Consequently, total shield thickness of the vacuum vessel in inboard and outboard, and additional shielding in the present design is expected to be enough.

Detection of Micro Cracks in a Model Structure under Thermal Transient Loading by Micro Indentation Test.

The micro hardness testing machine was applied to detect micro cracks on the model vessel under cyclic thermal transient with creep and fatigue. Micro hardness by the micro indentation test was measured along thickness of the model vessel. The micro hardness value decreased in the region of intergranular cracks from surface of the vesel and increased near the crack tip in comparison with no crack region. The decrease of micro hardness value in the crack region corresponded to creep-fatigue damage Dg1 under the cyclic thermal transient, where the creep-fatigue damage was calculated by the linear damage fraction rule. The micro indentation method was applicable to the detection of micro cracks.

Creep considerations for the lower head

The purpose of this technical note is to illustrate how creep on the inside high temperature portion of the lower head thickness of reactor vessel acts to relieve stresses. The creep behavior of the vessel lower head requires detailed finite-element-based finite-strain time-dependent analysis

Effects of acute and chronic treatment of haloperidol, clozapine and sulpiride on c-fos mRNA expression in rat forebrain regions

Stable VN micro-alloying for WH630E steel plate can be achieved by utilization of blowing nitrogen at the bottom of BOF and refining process. Steel plate WH630E with thickness of 8-25 mm was rolled by TMCP process and was treated by normalizing. By comparing mechanical properties and microstructure changes in as-rolled plate and normalized plates, it was found out that ferrite grain size can be refined by normalizing process and the low temperature impact energy can be improved by normalizing. The main Strengthening mechanism for normalized WH630E steel plate was ferrite grain refining, grain refining plays a more stronger role than V(CN) precipitation strengthening. Cold crack and reheated crack can be avoided by preheating treatment with no more than 170 ̊C before welding WH630E plate, strength and toughness for welded joint can have good match with the base metal by the process of 15∼35 kJ/cm welding heat input energy and 500∼580 ̊C SR(stress relief)heat treatment. Yield strength of normalized high strength pressure vessel steel plate can be improved by VN micro-alloying, and then the wall thickness of pressure vessel can be thinned or operating pressure can be increased, therefore overall weight of transportable pressure vessel can be reduced, and there will be significant economic and social benefits for the application of this kind pressure vessel steel plate.

Eddy Current Analysis of Superconducting Magnets for Magnetically Levitated Trains-Influence of Ground Coil Harmonics.

For the practical design of the superconducting magnet for high speed trains, the heat encroachment to the liquid helium and the mechanical deformation of the magnet must be solved.Our purpose is the estimation of very small Joule loss in the liquid helium vessel and magnetic force distribution caused by the ‘6-th harmonics’ flux from the ground coils for levitation. To estimate this small loss and magnetic force distribution accurately, a big scale 3-dimensional analysis considering the complex structure is necessary. However, the full model of the magnet couldn't be analyzed. The conventional thin conductor approximation method cannot solve this model accurately, because the vacuum vessel is thicker than its skin depth.In this paper, by using the finite element method with edge elements and EWS mounted full memory 512MByte, the small loss, magnetic force distribution and eddy current phase varying on thickness of the vacuum vessel is solved accurately.