Coolant Tubes Research Articles

An Assessment Of Critical Thermal-Hydraulic Problems in A Deuterium-Tritium Solid Breeder Blanket

Steady-state thermal-hydraulic analyses were carried out for the DEMO/STARFIRE fusion reactor based on solid breeder blankets and pressurized water as the coolant. The results of the parametric studies show that a coolant in-tube design, i.e., coolant tubes embedded in solid breeder blanket, with a contact resistance between the coolant tube and the solid breeder tailored to maintain the operating temperature window (i.e., the maximum and the minimum temperature imposed on the solid breeder) is viable. However, design of such a solid breeder blanket will present serious challenges because of uncertainty in the thermophysical properties of breeder materials, the narrow operating temperature window, the close manufacturing tolerances necessary to control the gap conductance, the sensitivity of tritium inventory and tritium extraction to breeder temperature distribution, and the deleterious effect of neutron irradiation on breeder material properties. The study shows that even modest uncertainties in the thermal conductivity of solid breeders, interfacial gap conductances, and operating power levels can have significant impact on blanket design. Therefore, the designer should include the expected variations in these parameters. Experimental programs are needed to quantify the above factors and to develop methods (e.g., insulated coatings) for gap conductance control and in situ recovery of tritiummore » via helium purge gas channels.« less

Design and Analysis of the Solid Breeder Integral Simulation Test for PE-IIa

The PE-II Solid Breeder Concept Integral Simulation Test is designed to simulate (by way of nonnuclear heating) the thermal-hydraulic/ thermomechanical operating characteristics of a water-cooled, Li/sub 2/O fusion reactor blanket. The test piece consists of a central coolant tube surrounded by a cylinder of solid breeder material. This test piece, which simulates a unit cell of a blanket, is then subjected to an external heat flux and a purge flow of helium at carefully controlled conditions. Instrumentation provides information on temperature profiles, moisture levels, and purge flow conditions. Pretest thermal/stress analysis of this experiment indicates that it can provide an accurate simulation of actual conditions in a prototypical fusion reactor blanket.

Design and Construction of a Low-Flow, Low-Power Torch for Inductively Coupled Plasma Spectrometry

A detailed study of the importance of various spatial dimensions in an ICP torch is described. Of the various dimensions which were examined, the annular spacing between the coolant (outer) and plasma (flared) tube is the most critical for plasma stabilization at low argon coolant flows and applied radio-frequency powers. Similarly, the inner diameter of the aerosol injection tube was found to be important, with the value of 1.0 mm chosen for a compromise between low-power, low-flow capability and routine analysis of high-solids sample solutions. A constriction at the inlet of the coolant argon was found not to affect plasma stability greatly, but altered significantly the applied powers and coolant flows which were necessary for plasma ignition. With these and other torch dimensions optimized, it was found to be possible to ignite a plasma at a coolant flow of 5 L/min and an applied radio frequency power of 450 W. Continued operation of the plasma during analysis of real samples or during aspiration of a 1% NaCl solution was found to be possible alternatively at 500 W (rf power) and 3.5 L/min coolant argon or 125 W and 5.5 L/min, respectively.

Characteristics of the background emission spectrum from a miniature inductively-coupled plasma

The spectral characteristics of the background radiation emitted by a miniature inductively-coupled plasma (i.c.p.) are carefully examined and methods for reducing undesirable features discussed. The complex nature of the background emission spectrum for the mini-i.c.p. indicates that careful line selection criteria and background correction procedures should be employed. Extending the torch coolant tube to the bottom of the region being observed in the plasma proved to be the most effective method for reducing undesirable spectral band features. Acute changes in background emission levels with r.f. power and nebulizer gas flow rates emphasize the need for careful control of these parameters to achieve high precision. Comparison between mini-i.c.p. and conventional i.c.p. spectra reveals the basic similarity of the two sources.

Fabrication of Grid-Spaced Bundle for the F-5 (X317) Irradiation Experiment

The fabrication of special components and hardware and the assembly of the grid-spaced bundle for the gas-cooled fast breeder reactor (GCFR) F-5 (X317) irradiation experiment now being irradiated in row 5 of the Experimental Breeder Reactor II are described. The F-5 experiment consists of 31 fueled rods and six coolant bypass tubes for the initial loading. The components fabricated and assembled by General Atomic Company are ribbed cladding, UO/sub 2/ blanket pellets (80% +- 2% TD), fission product traps, dosimeters, insulated flow bypass tubes, grid spacers, specially shaped axial spacer tubes, a thermal shield/orifice/flow mixer, a bundle attachment ring, hexagonal tubes with key slots for rod holddown, a rail assembly with attachment to the bottom subassembly shield, dummy fuel rods for flow testing, and assembly of the grid-spaced bundle including check-fit into the flow duct. A variety of fabrication methods, including powder pressing, sintering, outer diameter grinding, thread grinding, metal forming, machining, chemical milling, electrical discharge machining, and tungsten inert gas welding, were used to produce the components.

A High Power Inductively Coupled Plasma Torch and Impedance Matching Network

The relative ease of operation, power handling capabilities, and overall performance of an inductively coupled plasma-optical emission spectrometer depends upon numerous factors, not the least important of which is the design of the torch. A variety of such designs has appeared in the literature. Most workers have employed three concentric fused silica and/or Pyrex tubes, referred to as an inner sample gas tube, a flaired mouth plasma gas tube, and an outer coolant tube. These tubes are either fused into one- or two-piece units through glass blowing techniques or mounted in some type of dismantleable base assembly.

Review: BNL Tokamak graphite blanket design concepts

The BNL minimum activity graphite blanket designs are reviewed, and three are discussed in the context of an experimental power reactor (EPR) and commercial power reactor. Basically, the three designs employ a 30 cm or thicker graphite screen. Bremsstrahlung energy is deposited on the graphite surface and re-radiated away as thermal radiation. Fast neutrons are slowed down in the graphite, depositing most of their energy, which is then radiated to a secondary blanket with coolant tubes, as in types A and B, or removed by intermittent direct gas cooling (type C). In types A and B, radiation damage to the coolant tubes in the secondary blanket is reduced by one or two orders of magnitude, while in type C, the blanket is only cooled when the reactor is shut down, so that coolant cannot quench the plasma.

Parametric study of flat plate solar collectors

An analytical program, suitable for use on a digital computer is developed for the purpose of studying the hourly behavior of a flat plate solar collector. The influence of a large variety of collector parameters over the period of a year are shown in the plotted results. The solar energy that arrives at the collector is based on average conditions for the State of Rhode Island. Weather Bureau records and Eppley Laboratory data for the past ten years were studied to determine the ambient temperature, average diffuse radiation on clear days, average cloudiness, and influence of cloudiness on total radiation. These quantities were then put in the form of empirical equations so that they would predict the proper input for a computer program. The results indicate that the energy absorbed by a collector and its daily efficiency are strongly dependent on collector temperature and cloudiness. One must be very careful not to report a collector efficiency without giving the conditions under which a collector operates and the collector geometry. The results presented in this paper show the influence of cloudiness, collector temperature, number of covers, wind velocity, air space heat transfer coefficient, coolant heat transfer coefficient, tube spacing, azimuth angle and slope of surface, and plate absorptivity on collector performance.

Effect of Wall Temperature Spatial Variations on Aerodynamic Heatingto an Actively Cooled Aircraft

The design of cooled skin panels, which requires consideration of many parameters such as heat load, skin thickness, panel size, tube spacing, tube size, temperature limits, coolant flow, etc., must minimize weight and thermal stresses. A design procedure for such panels has been developed by Bell Aerospace Company (Helenbrook and Anthony, 1971). This design procedure assumes a uniform heating rate to the panel, i.e., the variation of aerodynamic heating rate due to the cyclic wall temperature distribution, which results from the discrete coolant tube locations in such a panel, has been neglected. This study was made to determine if these variations were sufficiently large to cause variations in aerodynamic heating rate which would require coupling of boundary layer and conductive thermal analysis solutions.

A variable temperature cryostat with external coolant source for the preparation and measurement of thin film in vacuum

The cryostat is basically the one designed by Klipping et al. Coolant is sucked from an outside reservoir through passages in the cryostat proper, from there to passages in its radiation shield, and then to a vacuum pump through a control valve. The cryostat can be kept at any desired temperature above that of liquid helium for long periods, consuming only small amounts of coolant. The underside of the main cryostat body is flat and has provisions for the attachment of thin film specimens and auxiliary equipment. The cryostat is mounted under a vacuum belljar together with an evaporation source for the preparation of thin-film samples, so that measurements can be made on a sample without exposing it to the atmosphere after its preparation. Coolant inlet and outlet tubes are concentric and pass through a single hole in the baseplate.

A Simulation of a Generalized Thermal Radiating Fin

The purpose of this paper is to provide a method for designing radiator fins with maximum heat removal capability per pound of construction material. This problem becomes important when radiators are designed for space applications, since all of the heat from the thermodynamic cycle must be removed by means of radiation. Moreover, space transportation vehicles are seriously limited as to payload, so that weight must be saved in all parts of a power plant. An increase in the output of a space power plant does not change the reactor, turbine, and generator as much as the radiator, with the result that, for megawatt electrical systems, the radiator is the dominant weight contributing component. A radiator could be built of coolant tubes alone, but this increases certain hazards. Meteor punctures can occur, so that the amount of area devoted to coolant tubes should be reduced as much as pos sible. Fins attached between the tubes can perform this function by extending the heat radiating surface. The extra weight of the fins is partly compensated for by a reduction in tubes and coolant. Extra savings can occur if the weight of the fin is minimized; optimum thickness, length, and cross section must be found. This paper studies the relationship between fin cross- section and radiating power.