The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform
N Kasinathan - One of the best experts on this subject based on the ideXlab platform.
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numerical prediction of fire extinguishment characteristics of sodium leak Collection Tray in a fast breeder reactor
Nuclear Engineering and Design, 2011Co-Authors: S V Diwakar, N Kasinathan, T SundararajanAbstract:Abstract Sodium leak Collection Tray (LCT) is an efficient passive device used for the extinguishment of liquid sodium fire in case of an accidental leakage from the secondary circuit of a fast breeder reactor. The LCT essentially isolates the leaking sodium into closed containers where the resulting fire is extinguished due to limited availability of oxygen. The current work aims to highlight the combustion extinguishment characteristics of LCT through a lumped formulation by conserving the mass and energy of liquid sodium and constituent gases in various parts of the LCT. Here, the complex hydrodynamics of liquid sodium is emulated through a semi-analytical draining/sloshing model and its burning rates are predicted through a three-dimensional open pool combustion model for the Tray region and a closed pool combustion model for the holdup vessel. These simulations evaluate the burning rates at discrete levels of liquid sodium which are subsequently interpolated to establish correlations involving instantaneous liquid levels and oxygen concentration. Using the correlations obtained from the draining and combustion models, the overall lumped formulation directly predicts the un-burnt sodium recoverable after the extinguishment of fire in the LCT. The predicted results of this model compare well with the available experimental data.
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thermal hydraulic analysis towards a robust design of leak Collection Tray for pool type sodium cooled fast reactors
18th International Conference on Nuclear Engineering: Volume 3, 2010Co-Authors: Anil Kumar Sharma, N Kasinathan, K Velusamy, P Chellapandi, S C ChetalAbstract:To protect the sodium cooled FBR plant against the hazardous effects of sodium leak into the ambient, one of the passive protection devices used is the Leak Collection Trays (LCT) below the secondary sodium carrying pipelines in the Steam Generator Building (SGB). The design of LCT is based on immediate channeling of burning liquid sodium on the funnel shaped ‘sloping cover Tray’ to the bottom ‘sodium hold-up vessel’ in which self-extinction of the fire occurs due to oxygen starvation. In the secondary heat transfer circuits of FBRs, leakage of liquid sodium from the pipelines is postulated as one of the design basis accidents with probability of occurrence at 10−2 per reactor year. LCT collect the leaked sodium in a hold up vessel, suppress the sodium fire due to oxygen starvation and guide the sodium to an inerted ‘sodium transfer tank’ located at the bottom most elevation of the SGB. The procedure of draining the leaked sodium into the transfer tank has been envisaged as a defense in depth measure against the handling of un-burnt sodium and to guard against larger leak rates than that can be handled by the LCT effectively. Towards this, a network of carbon steel pipelines are laid out connecting all the LCT and the transfer tank through headers in strategic locations, each having a fusible plug. The fusible plug separates the air environment in LCT and argon environment in sodium transfer tank. Woods metal is the preliminary choice for the fusible plug. It is an alloy of 50% Bi, 25% Pb, 12.5% Sn and 12.5% Cd with a melting point of 72°C. The transfer tank is filled with argon at ∼ 0.03 bars-g pressure. Both the header and the tank are at room temperature during normal conditions. Leaked sodium by virtue of its high temperature has to heat up the fusible plug to melt the same and drain into the transfer tank. Transient thermal hydraulic investigations have been carried out to predict the fusing characteristics of woods metal plug. The numerical results have been validated against analytical solutions for idealized conditions. Detailed parametric studies have been carried out with plug thickness as a parameter. It is established that effective melting of the plug and trouble free draining of the leaked sodium is possible for a 3 mm thick fusible plug.Copyright © 2010 by ASME
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development of mathematical model for optimization of sodium leak Collection Tray
Nuclear Engineering and Design, 2008Co-Authors: S V Diwakar, T Sundararajan, N KasinathanAbstract:Sodium leaks and resultant fire containment play an important role in the safe operation of a fast breeder reactor. Leak Collection Tray (LCT) is a passive device which is used to collect the highly reactive liquid sodium in the case of an accidental leakage. The consequences of sodium fire are mitigated by oxygen starvation in the vessel which collects the liquid sodium after leakage. The current paper deals with the optimization of the LCT geometry based on the hydrodynamic characteristics of the leaked liquid sodium. Isothermal numerical simulations have been performed to understand the interfacial dynamics of the hot liquid sodium flow in the top Tray part and the variation of sodium draining rate into the holdup vessel for various drainpipe diameters and leak rates. Since the numerical simulations involve very high computational effort, an equivalent semi-analytical sloshing/draining model has also been developed which emulates the flow process in the LCT. The predictions of transient mass distributions in the top part and in the holdup vessel for the semi-analytical model are in close match with the results obtained from the detailed numerical study. The results reveal critical geometric parameters at which the un-burnt sodium collected in the LCT will be maximum.
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experimental evaluation of pool fire suppression performance of sodium leak Collection Tray in open air
Volume 5: Safety and Security; Low Level Waste Management Decontamination and Decommissioning; Nuclear Industry Forum, 2006Co-Authors: F C Parida, N Kasinathan, S S Ramesh, B Malarvizhi, V Gopalakrishnan, S E KannanAbstract:In the event of sodium leakage from heat transfer circuits of fast breeder reactors (FBR), liquid sodium catches fire in ambient air leading to production of flame, smoke and heat. One of the passive fire protection methods involves immediate Collection of the leaking sodium to a sodium hold-up vessel (SHV) covered with a sloping cover Tray (SCT) having a few drain pipes and one vent pipe (as in Fig. 1). As soon as the liquid sodium falls on the sloping cover Tray, gravity guides the sodium through drain pipes into the bottom Tray in which self-extinction occurs due to oxygen starvation. This sodium fire protection equipment called leak Collection Tray (LCT) works without the intervention of an operator and external power source. A large number of LCTs are strategically arranged under the sodium circulating pipe lines in the FBR plants to serve as passive suppression devices. In order to test the efficacy of the LCT, four tests were conducted. Two tests were with LCT having three drain pipes and rest with one. In each experiment, nearly 40 kg of hot liquid sodium at 550 deg. C was discharged on the LCT in the open air. Continuous on-line monitoring of temperaturemore » at strategic locations ({approx} 28 points) were carried out. Colour video-graphy was employed for taking motion pictures of various time-dependent events like sodium dumping, appearance of flame and release of smoke through vent pipes. After self-extinction of sodium fire, the LCT was allowed to cool overnight in an argon atmosphere. Solid samples of sodium debris in the SCT and SHV were collected by manual core drilling machine. The samples were subjected to chemical analysis for determination of unburnt and burnt sodium. The results of the four tests revealed an interesting feature: LCT with three drain pipes showed far lower sodium Collection efficiency and much higher sodium combustion than that with just one drain pipe. Thermal fluctuations in temperature sensor located near the tip of the drain pipe have indicated that transient freezing and remelting processes are responsible for this phenomenon. Moreover comparison of test results between present and earlier experiments has revealed that the LCT with funnel shaped SCT is superior to that with boat shaped SCT. (authors)« less
Ruxu Du - One of the best experts on this subject based on the ideXlab platform.
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A precision CNC turn-mill machining center with gear hobbing capability
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2015Co-Authors: Xianshuai Chen, Wei Feng, Songmei Yuan, Ruxu DuAbstract:Abstract With ever increasing demand for small parts with complex shapes and high dimensional accuracy, many traditional machine tools have become ineffective for machining these miniature components. Typical examples include dental implants, parts used in mechanical watch movements, and parts used in medical endoscopes. This paper introduces our PC-controlled CNC turn-mill machining center. It has 5 axes, an automatic bar feeder, an automatic part Collection Tray, and a tool changer. It features a special control algorithm for the synchronization of its axes that produces not only higher accuracy but also makes the machine easier to use. In addition, a volumetric error compensation algorithm is implemented to improve accuracy. Based on experiments, the machining error is ±3 μm for turning, ±7 μm for milling and the maximum profile error is less than ±7.5 μm for gear hobbing.
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A Precision CNC Turn-Mill Machining Center with Gear Hobbing Capability
Applied Mechanics and Materials, 2013Co-Authors: Xianshuai Chen, Songmei Yuan, Dai Lin Zhang, Xiao Zhang, Jian Yu Chen, Ruxu DuAbstract:With ever increased demand for reduced sizes and increased complexity and accuracy, traditional machine tools have become ineffective for machining miniature components. Typical examples include dental implants, the parts used in mechanical watch movement, and the parts used in medical endoscope. With complex geometry and tight tolerance, few machine tools are capable of making them. This paper introduces our PC-based CNC Turn-Mill Machining Center. It has 5 axes, an automatic bar feeder, an automatic part Collection Tray, and a tool changer. In particularly, it has a special synchronization control algorithm that gives not only higher accuracy but also ease of use. In addition, to improve the accuracy, the software based volumetric error compensation system is implemented. Based on the experiment testing, the machining error is ± 3 µm in turning, ± 7 µm in milling and the maximum profile error is less than ± 7.5 µm in gear hobbing.
Xianshuai Chen - One of the best experts on this subject based on the ideXlab platform.
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A precision CNC turn-mill machining center with gear hobbing capability
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2015Co-Authors: Xianshuai Chen, Wei Feng, Songmei Yuan, Ruxu DuAbstract:Abstract With ever increasing demand for small parts with complex shapes and high dimensional accuracy, many traditional machine tools have become ineffective for machining these miniature components. Typical examples include dental implants, parts used in mechanical watch movements, and parts used in medical endoscopes. This paper introduces our PC-controlled CNC turn-mill machining center. It has 5 axes, an automatic bar feeder, an automatic part Collection Tray, and a tool changer. It features a special control algorithm for the synchronization of its axes that produces not only higher accuracy but also makes the machine easier to use. In addition, a volumetric error compensation algorithm is implemented to improve accuracy. Based on experiments, the machining error is ±3 μm for turning, ±7 μm for milling and the maximum profile error is less than ±7.5 μm for gear hobbing.
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A Precision CNC Turn-Mill Machining Center with Gear Hobbing Capability
Applied Mechanics and Materials, 2013Co-Authors: Xianshuai Chen, Songmei Yuan, Dai Lin Zhang, Xiao Zhang, Jian Yu Chen, Ruxu DuAbstract:With ever increased demand for reduced sizes and increased complexity and accuracy, traditional machine tools have become ineffective for machining miniature components. Typical examples include dental implants, the parts used in mechanical watch movement, and the parts used in medical endoscope. With complex geometry and tight tolerance, few machine tools are capable of making them. This paper introduces our PC-based CNC Turn-Mill Machining Center. It has 5 axes, an automatic bar feeder, an automatic part Collection Tray, and a tool changer. In particularly, it has a special synchronization control algorithm that gives not only higher accuracy but also ease of use. In addition, to improve the accuracy, the software based volumetric error compensation system is implemented. Based on the experiment testing, the machining error is ± 3 µm in turning, ± 7 µm in milling and the maximum profile error is less than ± 7.5 µm in gear hobbing.
A.l. Pitner - One of the best experts on this subject based on the ideXlab platform.
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Acceptance Test Plan for the Sludge Pickup Adaptor
2000Co-Authors: A.l. PitnerAbstract:This test plan documents the acceptance testing of the sludge pickup adapter for potential use during PSI Phases 3 and 4 fuel cleanliness inspection activities. The adaptex is attached to the strainer tip of the vacuum wand and used to suction up residual sludge captured in a sludge Collection Tray. The material is vacuumed into a chamber of known volume in the sludge pickup adapter. The device serves as an aid in helping to determine whether the observed quantity of sludge is within allowable limits (1.4 cm{sup 3} per fuel assembly). This functionality test involves underwater testing in the 305 Building Cold Test Facility to verify that sludge can be successfully vacuumed from a Collection Tray. Ancillary activities in this acceptance test include demonstration that the sludge pickup adapter CM be successfully attached to and detached from the vacuum wand underwater.
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Engineering Work Plan for Development of Sludge Pickup Adapter for Fuel Cleanliness Inspections
2000Co-Authors: A.l. PitnerAbstract:The plan for developing an adapter to suction up sludge into a calibrated tube for fuel cleanliness inspection activities is described. A primary assessment of fuel cleanliness to be performed after processing through the Primary Cleaning Machine is whether the volume of any remaining canister sludge in or on a fuel assembly exceeds the allowable 14 cm{sup 3} limit. It is anticipated that a general visual inspection of the sludge inventory after fuel assembly separation will usually suffice in making this assessment, but occasions may arise where there is some question as to whether or not the observed quantity of sludge exceeds this limit. Therefore a quantitative method of collecting and measuring the sludge volume is needed for these borderline situations. It is proposed to develop an adapter that fits on the end of the secondary cleaning station vacuum wand that will suction the material from the sludge Collection Tray into a chamber marked with the limiting volume to permit a direct go/no-go assessment of the sludge quantity.
T Sundararajan - One of the best experts on this subject based on the ideXlab platform.
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numerical prediction of fire extinguishment characteristics of sodium leak Collection Tray in a fast breeder reactor
Nuclear Engineering and Design, 2011Co-Authors: S V Diwakar, N Kasinathan, T SundararajanAbstract:Abstract Sodium leak Collection Tray (LCT) is an efficient passive device used for the extinguishment of liquid sodium fire in case of an accidental leakage from the secondary circuit of a fast breeder reactor. The LCT essentially isolates the leaking sodium into closed containers where the resulting fire is extinguished due to limited availability of oxygen. The current work aims to highlight the combustion extinguishment characteristics of LCT through a lumped formulation by conserving the mass and energy of liquid sodium and constituent gases in various parts of the LCT. Here, the complex hydrodynamics of liquid sodium is emulated through a semi-analytical draining/sloshing model and its burning rates are predicted through a three-dimensional open pool combustion model for the Tray region and a closed pool combustion model for the holdup vessel. These simulations evaluate the burning rates at discrete levels of liquid sodium which are subsequently interpolated to establish correlations involving instantaneous liquid levels and oxygen concentration. Using the correlations obtained from the draining and combustion models, the overall lumped formulation directly predicts the un-burnt sodium recoverable after the extinguishment of fire in the LCT. The predicted results of this model compare well with the available experimental data.
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development of mathematical model for optimization of sodium leak Collection Tray
Nuclear Engineering and Design, 2008Co-Authors: S V Diwakar, T Sundararajan, N KasinathanAbstract:Sodium leaks and resultant fire containment play an important role in the safe operation of a fast breeder reactor. Leak Collection Tray (LCT) is a passive device which is used to collect the highly reactive liquid sodium in the case of an accidental leakage. The consequences of sodium fire are mitigated by oxygen starvation in the vessel which collects the liquid sodium after leakage. The current paper deals with the optimization of the LCT geometry based on the hydrodynamic characteristics of the leaked liquid sodium. Isothermal numerical simulations have been performed to understand the interfacial dynamics of the hot liquid sodium flow in the top Tray part and the variation of sodium draining rate into the holdup vessel for various drainpipe diameters and leak rates. Since the numerical simulations involve very high computational effort, an equivalent semi-analytical sloshing/draining model has also been developed which emulates the flow process in the LCT. The predictions of transient mass distributions in the top part and in the holdup vessel for the semi-analytical model are in close match with the results obtained from the detailed numerical study. The results reveal critical geometric parameters at which the un-burnt sodium collected in the LCT will be maximum.