Drum Failure Research Articles

Performance of square UHPC filled high-strength steel tubular columns under axial compression: Experiment and theory analysis

In this paper, 12 ultra-high performance concrete (UHPC) filled high-strength steel tubular (UHPCFST) short columns with square-section were subjected to axial compression tests. The effects of confinement factor (ξ) on the axial compression performance of UHPCFST were discussed, and the failure modes, axial load–strain curves, and strain responses were discussed. The results showed that the specimens mainly had two failure modes: shear failure and waist drum failure, and all specimens showed good ductility and high post-peak bearing capacity, indicating that high-strength steel tubes could provide higher restraint for UHPC and form a high-strength and high-performance steel-UHPC system. When ξ ≥ 1.42, the strength index (SI) increased significantly with the increase of ξ. When ξ ≤ 1.06, the SI was close to 1. With the increase of ξ, the ductility and toughness of the specimens were improved. Finally, considering the non-uniformity of the confinement of the core UHPC by the square-section steel tube, a calculation model of the ultimate compressive capacity of UHPCFST specimens with square-section was proposed. Compared with the seven classical models, the calculation model proposed in this paper was more accurate.

Mechanical performance of marine concrete filled CFRP-aluminum alloy tube columns under axial compression: Experiment and finite element analysis

This study presents the mechanical performance of marine concrete filled carbon fiber reinforced polymer (CFRP)-Aluminum alloy tube columns (CFRP-CFAT) through axial compression experiment and finite element analysis. 18 specimens were tested including 3 marine concrete filled aluminum alloy tubes (CFAT) and 15 CFRP-CFATs. The effects of the CFRP pasting position (outer and inner CFRP) and the number of CFRP layers were investigated. The typical failure pattern of specimens without inner CFRP was waist drum failure of aluminum alloy tube and concrete crushed, aluminum tube and concrete of specimens with inner CFRP were shear failure, the CFRP of all specimens was fractured. CFRP and aluminum alloy tube have fine deformation coordination performance. With the confinement of CFRP, the ultimate bearing capacity and energy absorption capacity of CFRP-CFATs were increased by up to 60.0% and 37.3%, respectively, also effectively inhibited the damage development of specimens. Moreover, a finite element model was developed, a parametric study was carried and a model for calculating the ultimate bearing capacity of CFRP-CFAT was proposed. The simulated results and calculated results were consistent with experimental results.

Neutronics analysis of a 200 kWe space nuclear reactor with an integrated honeycomb core design

Heat pipe cooled nuclear reactor has been a very attractive technical solution to provide the power for deep space applications. In this paper, a 200 kWe space nuclear reactor power design has been proposed based on the combination of an integrated UN ceramic fuel, a heat pipe cooling system and the Stirling power generators. Neutronics and thermal analysis have been performed on the space nuclear reactor. It was found that the entire reactor core has at least 3.9 $ subcritical even under the worst-case submersion accident superimposed a single safety drum failure, and results from fuel temperature coefficient, neutron spectrum and power distribution analysis also showed that this reactor design satisfies the neutronics requirements. Thermal analysis showed that the power in the core can be successfully removed both in normal operation or under one or more heat pipes failure scenarios.

Compressive performance of high-strength seawater and sea sand concrete-filled circular FRP-steel composite tube columns

A new high-strength seawater and sea sand concrete (HSSC)-filled circular FRP-steel composite tube (HFSCT) structure, consisting of an internal FRP, carbon steel tube and external FRP, was investigated in this study. Thirty-six specimens were tested to investigate the axial behaviour of HFSCTs. FRPs and steel tubes were used as the test parameters. The results indicate that the specimen failure modes change from shear failure to waist drum failure based on the steel tube thickness (4.5–7.0 mm). An increase in the FRP and steel tube significantly affect the axial compressive behaviour of HFSCTs. The ultimate stress of specimens confined by CFRPs is better than those confined by BFRPs; however, specimens confined by BFRPs show excellent ultimate deformation ability. Additionally, 155 axial compressive data samples of concrete-filled circular FRP-steel composite tube columns were collected to establish the test database. The calculation formulas for the ultimate stress, ultimate strain, peak stress and peak strain were developed by considering the efficiency of different FRP types in lateral confinement, which possess a more accurate applicability for concrete-filled circular FRP-steel composite tube columns. Last, a complete calculation model was recommended to predict the full nominal stress–strain curve and accurately reflect the stress–strain behaviour.

Behaviors of RPC-filled double skin steel tubular stub columns under axial compression loading

This paper presents the compressive behaviors of RPC-filled double skin steel tubular (RFDST) stub columns. Six RFDST stub column specimens, with different hollow ratios and constraint coefficients, were tested under axial compression loading. The compressive behaviors, such as failure mode, strength and ductility, were analyzed. It is found that the failure mode of RPC filled steel tube (RFST) stub column is shear failure, while RFDST stub columns are waist drum failure. The load deformation curves of RFDST specimens with different hollow ratio and constraint coefficient show different characteristics. RFDST specimens exhibit high bearing capacity and good ductility. Based on the test results of existing RFDST stub columns, a design formula for predicting the ultimate bearing capacity is given. A finite element model is also presented to analyze the compressive behaviors, and good agreement is obtained. The influences of hollow ratio and constraint coefficient on the ultimate bearing capacity are discussed.

An Investigation of Plume Response to Soil Vapor Extraction and Hypothetical Drum Failure

Core Ideas Soil vapor extraction (SVE) wells are an effective interim remediation technique. Flow and transport modeling assists in evaluation of vapor plume behavior. Plume simulations assuming drum failure and SVE provide a framework for remediation planning. A small borehole subset could be monitored for detection of VOC releases due to drum failure. Soil vapor extraction (SVE) has been used at sites across the Department of Energy complex, including sites where legacy subsurface wastes represent a potential source of groundwater contamination. At Los Alamos National Laboratory (LANL), leakage from waste drums buried at an inactive chemical waste site has created a subsurface vapor plume of volatile organic compounds (VOCs). Soil vapor extraction operation in 2015 and rebound testing through 2017 were successful in reducing the plume's mass and mitigating VOC migration toward the water table. However, the possibility that waste drums could fail and release VOCs could pose a challenge in the future. To explore the impacts of drum failure, as well as the capabilities of SVE remediation, we simulated hypothetical contaminant release scenarios and subsequent SVE remediation. Three‐dimensional subsurface VOC behavior, including advection, diffusion, and plume interactions with topography, were simulated using the porous flow simulator Finite Element Heat and Mass Transfer. Simulations of future site conditions have allowed identification of “sentry” boreholes that can be monitored for early detection in case of drum failure. Sentry boreholes can also be used to set concentration thresholds above which SVE should be initiated. For the LANL site, simulations show that SVE can be started 3 yr following drum failure and remain a viable remediation tool. More broadly, the principles outlined in this work can be used to support remediation planning at other subsurface waste sites. Predictive models of future releases can be analyzed to set concentration threshold values, guide selection of sentry boreholes, and increase operational efficiency.

Axial compression performance research on large diameter CFST column-beam connection after cycle reversed loading

In order to study the mechanical properties of large diameter CFST column-beam connection after earthquake, axial compression test was carried out on the connection specimens that experienced low cycle reversed loading. The failure shapes, ultimate bearing capacities and strains characteristics of the connection were investigated. The results show that the improved interior diaphragm CFST column-H-shaped steel beam joints show waist drum failure modes. The column-beam joints still have high axial bearing capacity after cycle reversed loading. The interior diaphragms and linking reinforcing bars effectively restrain the transverse deformation of the steel tube of the connection zone.

C&EN talks with David T. Hobbs, nuclear waste expert

David T. Hobbs is an expert in the complicated chemistry of nuclear waste management. He’s studied nuclear waste materials, radiochemical separations, and complex chemical environments for more than three decades. But three years ago, when an accident in a New Mexico repository brought disposal of U.S. defense nuclear wastes to a standstill, he was called to investigate a different kind of material—cat litter. Hobbs, who doesn’t own a cat, is one of the researchers who studied the nuclear waste mixture that in 2014 led to a drum failure and radiological release at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, N.M. The accident shut down the facility for three years. It was ultimately traced to an unorthodox sorbent, an organic cat litter called sWheat Scoop, that was used in error to prepare the nuclear waste for disposal at WIPP. After a 33-year tenure, Hobbs retires this month from Savannah River

Accident analysis of heat pipe cooled and AMTEC conversion space reactor system

A space power with high power density, light weight, low cost and high reliability is of crucial importance to future exploration of deep space. Space reactor is an excellent candidate because of its unique characteristics of high specific power, low cost, strong environment adaptability and so on. Among all types of space reactors, heat pipe cooled space reactor, which adopts the passive heat pipe (HP) as core cooling component, is considered as one of the most promising choices and is widely studied all over the world.This paper develops a transient analysis code (TAPIRS) for heat pipe cooled space reactor power system (HPS) based on point reactor kinetics model, lumped parameter core heat transfer model, combined HP model (self-diffusion model, flat-front startup model and network model), energy conversion model of Alkali Metal Thermal-to-Electric Conversion units (AMTEC), and HP radiator model. Three typical accidents, i.e., control drum failure, AMTEC failure and partial loss of the heat transfer area of radiator are then analyzed using TAPIRS. By comparing the simulation results of the models and steady state with those in the references, the rationality of the models and the solution method is validated. The results show the following. (1) After the failure of one set of control drums, the reactor power finally reaches a stable value after two local peaks under the temperature feedback. The fuel temperature rises rapidly, however it is still under safe limit. (2) The fuel temperature is below a safe limit under the AMTEC failure and partial loss of the heat transfer area of radiator. This demonstrates the rationality of the system design and the potential applicability of the TAPIRS code for the future engineering application of heat pipe cooled space reactor.

Study on startup characteristics of heat pipe cooled and AMTEC conversion space reactor system

Future exploration of deep space requires space power with high power density, light weight, low cost and high reliability. Space reactor is an excellent candidate with its unique characteristics of high specific power, low cost, strong environment adaptability and so on. Among all types of space reactors, heat pipe cooled space reactor, which adopts the passive heat pipe as core cooling component, is considered as one of the most promising choice and is widely studied all over the world. Startup characteristics of this type space reactor are an active topic.Previous studies mainly focused on the startup from high temperature rather than environmental temperature. In order to simulate the transient startup process from frozen state, a transient analysis code (TAPIRS) for heat pipe cooled space reactor power system (HPS) has been developed and applied to investigate the system transient performance during a startup from zero cold power to full power. The code integrates separately validated point reactor kinetics model, lumped parameter core heat transfer model, combined heat pipe (HP) model (self-diffusion model, flat-front startup model and network model), energy conversion model of alkali metal thermal-to-electric conversion units (AMTEC), and HP radiator model. By comparing the simulation results of the models and steady state with those in the references, the rationality of the models and the solution method is validated. It is found that by adjusting the control drum's rotational speed, the reactor can startup from subcritical state to full power state while the heat pipe and AMTEC from solid state to normal operational state. HPS can startup entirely depending on the nuclear power, and the maximum temperature of the heat pipe does not exceed 1250 K in the whole startup process. The maximum errors of the parameters between the simulation results of this paper and those in the literature at the full power condition are less than 5%. Under the accident of control drum failure with largest reactivity insertion, the fuel temperature can be controlled within the safety limits. These show that the reactor system has characteristics of no single-point failures, the self-stabilization capability under accident conditions.

Reliability Analysis Based on Fault Tree of Failure of Boiler Drum

Drum is the core pressure equipment of Natural Circulation Boiler. The harsh working conditions lead drum to be prone to failure in power station boiler system. This article presents a systematic analysis of factors which may cause the failure of the drum and builds the fault tree with the drum failure as the top event. Through calculating each order of minimum cut sets and importance degree of each basic event probability to determine the major influent factors for the failure of drum, this article puts forward the corresponding solutions and brings reference value to safe operation and maintenance of boiler drum.

Brittle fractures of the drums of high-pressure boilers: Main causes and methods for preventing them

Factors causing damage to the metal of the drums of high-pressure boilers, as well as the known cases of drum failures, are analyzed. The totality of factors determining the operational reliability of drums is systematized. The process-related mechanism governing the destruction of the drums at the Kurgan cogeneration station and TETs-3 Yaroslavl cogeneration station, and the general factors caused these drums to fail are identified. Recommendations for reducing the risk of drum failures are formulated.

Crack growth modelling and probabilistic life assessment of coke drums operating under fatigue conditions

Coke drums are thin-walled pressure vessels that experience some of the most severe thermal cycling conditions of all the components on a refinery. The consequential high thermal stresses, applied in a cyclic manner, can lead to premature drum failure in the form of through wall low cycle fatigue cracking. Increasingly, coke drum operators are adopting risk based inspection and maintenance scheduling; utilising instrumentation for the on-line monitoring of strains and temperatures on the drums during cyclic operation as the technical basis for decision-making. The data collected can be analysed deterministically using classical solutions to enable the computation of mechanical and thermal stresses. Alternatively, the data can be treated statistically to form part of the input to a probabilistic assessment, which can be used to infer the cumulative probabilities of crack initiation and failure as functions of operational cycles, thus quantifying the likely risks associated with future operation. This latter approach enables both technical and economic factors to be reconciled when making decisions regarding future maintenance, inspection and replacement strategies. The approach has the advantage, amongst others, of reconciling potential variability of input data, for example, local material property variations and variable measured strain ranges, without being unnecessarily conservative.

An Investigation into Flange Forces in Winch Drums

This paper describes a series of experimental tests which were carried out to investigate the forces acting on a winch drum during multi-layer rope winding. Consideration is given mainly to flange forces which are one of the prime causes of winch drum failure. A new method of measuring flange forces is demonstrated and comparisons are made of test results for different rope constructions, rope tensions and spooling. To aid winch designers and operators, flange design curves are suggested which may be used to predict the failure limits of winch drums.