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Sample records for controlled thermonuclear reactor

  1. Feedback control of major disruptions in International Thermonuclear Experimental Reactor

    SciTech Connect

    Sen, A. K.

    2011-08-15

    It is argued that major disruptions in ITER can be avoided by the feedback control of the causative MHD precursors. The sensors will be 2D-arrays of ECE detectors and the suppressors will be modulated ECH beams injected radially to produce non-thermal radial pressures to counter the radial dynamics of MHD modes. The appropriate amplitude and phase of this signal can stabilize the relevant MHD modes and prevent their evolution to a major disruption. For multimode MHD precursors, an optimal feedback scheme with a Kalman filter is discussed.

  2. The polonium-210 problem in thermonuclear reactor

    SciTech Connect

    Shchipakhin, O.L.; Borisov, N.B.; Churkin, S.L.

    1993-12-31

    Polonium 210 forms in the lithium-lead eutectic blanket of a thermonuclear reactor. On the basis of obtained experimental data some estimates have been calculated on the ITER blanket accident consequences. The LOCA type accident represents the failure of eutectic circuit in the process of transfusion of liquid eutectic from blanket to the tritium reprocessing plant.

  3. Current drive for stability of thermonuclear plasma reactor

    NASA Astrophysics Data System (ADS)

    Amicucci, L.; Cardinali, A.; Castaldo, C.; Cesario, R.; Galli, A.; Panaccione, L.; Paoletti, F.; Schettini, G.; Spigler, R.; Tuccillo, A.

    2016-01-01

    To produce in a thermonuclear fusion reactor based on the tokamak concept a sufficiently high fusion gain together stability necessary for operations represent a major challenge, which depends on the capability of driving non-inductive current in the hydrogen plasma. This request should be satisfied by radio-frequency (RF) power suitable for producing the lower hybrid current drive (LHCD) effect, recently demonstrated successfully occurring also at reactor-graded high plasma densities. An LHCD-based tool should be in principle capable of tailoring the plasma current density in the outer radial half of plasma column, where other methods are much less effective, in order to ensure operations in the presence of unpredictably changes of the plasma pressure profiles. In the presence of too high electron temperatures even at the periphery of the plasma column, as envisaged in DEMO reactor, the penetration of the coupled RF power into the plasma core was believed for long time problematic and, only recently, numerical modelling results based on standard plasma wave theory, have shown that this problem should be solved by using suitable parameter of the antenna power spectrum. We show here further information on the new understanding of the RF power deposition profile dependence on antenna parameters, which supports the conclusion that current can be actively driven over a broad layer of the outer radial half of plasma column, thus enabling current profile control necessary for the stability of a reactor.

  4. Plasma physics and controlled thermonuclear fusion

    SciTech Connect

    Krikorian, R. )

    1989-01-01

    This proceedings contains papers on plasma physics and controlled thermonuclear fusion. Included are the following topics: Plasma focus and Z-pinch, Review of mirror fusion research, Progress in studies of x-ray and ion-beam emission from plasma focus facilities.

  5. Thermonuclear inverse magnetic pumping power cycle for stellarator reactors

    NASA Astrophysics Data System (ADS)

    Ho, D. D. M.; Kulsrud, R. M.

    1985-09-01

    A novel power cycle for direct conversion of alpha-particle energy into electricity is proposed for an ignited plasma in a stellerator reactor. The plasma column is alternately compressed and expanded in minor radius by periodic variation of the toroidal magnetic field strength. As a result of the way a stellarator is expected to work, the plasma pressure during expansion is greater than the corresponding pressure during compression. Therefore, negative work is done on the plasma during a complete cycle. This work manifests itself as a back-voltage in the toroidal field coils, and direct electrical energy is obtained from this voltage. For a typical reactor, the average power obtained from this cycle (with a minor radius compression factor on the order of 50%) can be as much as 50% of the electrical power obtained from the thermonuclear neutrons without compressing the plasma. Thus, if it is feasible to vary the toroidal field strength, the power cycle provides an alternative scheme of energy conversion for a deuterium-tritium fueled reactor. The cycle may become an important method of energy conversion for advanced neutron-lean fueled reactors. By operating two or more reactors in tandem, the cycle can be made self-sustaining.

  6. Energy Balance of Controlled Thermonuclear Fusion

    NASA Astrophysics Data System (ADS)

    Hashmi, M.; Staudenmaier, G.

    It is shown that a discrepancy and incompatibility persist between basic physics and fusion-literature regarding the radiation losses from a thermonuclear plasma. Whereas the fusion-literature neglects the excitation or line radiation completely, according to basic physics it depends upon the prevailing conditions and cannot be neglected in general. Moreover, for a magnetized plasma, while the fusion-literature assumes a self-absorption or reabsorption of cyclotron or synchrotron radiation emitted by the electrons spiraling along the magnetic field, the basic physics does not allow any effective reabsorption of cyclotron or synchrotron radiation. As is demonstrated, fallacious assumptions and notions, which somehow or other crept into the fusion-literature, are responsible for this discrepancy. In the present work, the theory is corrected. On the grounds of basic physics, a complete energy balance of magnetized and non-magnetized plasmas is presented for pulsed, stationary and self-sustaining operations by taking into account the energy release by reactions of light nuclei as well as different kinds of diffusive (conduction) and radiative (bremsstrahlung, cyclotron or synchrotron radiation and excitation radiation) energy losses. Already the energy losses by radiation make the energy balance negative. Hence, a fusion reactor - an energy producing device - seems to be beyond the realms of realization.

  7. Current drive at plasma densities required for thermonuclear reactors.

    PubMed

    Cesario, R; Amicucci, L; Cardinali, A; Castaldo, C; Marinucci, M; Panaccione, L; Santini, F; Tudisco, O; Apicella, M L; Calabrò, G; Cianfarani, C; Frigione, D; Galli, A; Mazzitelli, G; Mazzotta, C; Pericoli, V; Schettini, G; Tuccillo, A A

    2010-08-10

    Progress in thermonuclear fusion energy research based on deuterium plasmas magnetically confined in toroidal tokamak devices requires the development of efficient current drive methods. Previous experiments have shown that plasma current can be driven effectively by externally launched radio frequency power coupled to lower hybrid plasma waves. However, at the high plasma densities required for fusion power plants, the coupled radio frequency power does not penetrate into the plasma core, possibly because of strong wave interactions with the plasma edge. Here we show experiments performed on FTU (Frascati Tokamak Upgrade) based on theoretical predictions that nonlinear interactions diminish when the peripheral plasma electron temperature is high, allowing significant wave penetration at high density. The results show that the coupled radio frequency power can penetrate into high-density plasmas due to weaker plasma edge effects, thus extending the effective range of lower hybrid current drive towards the domain relevant for fusion reactors.

  8. Operating large controlled thermonuclear fusion research facilities

    SciTech Connect

    Gaudreau, M.P.J.; Tarrh, J.M.; Post, R.S.; Thomas, P.

    1987-10-01

    The MIT Tara Tandem Mirror is a large, state of the art controlled thermonuclear fusion research facility. Over the six years of its design, implementation, and operation, every effort was made to minimize cost and maximize performance by using the best and latest hardware, software, and scientific and operational techniques. After reviewing all major DOE fusion facilities, an independent DOE review committee concluded that the Tara operation was the most automated and efficient of all DOE facilities. This paper includes a review of the key elements of the Tara design, construction, operation, management, physics milestones, and funding that led to this success. We emphasize a chronological description of how the system evolved from the proposal stage to a mature device with an emphasis on the basic philosophies behind the implementation process. This description can serve both as a qualitative and quantitative database for future large experiment planning. It includes actual final costs and manpower spent as well as actual run and maintenance schedules, number of data shots, major system failures, etc. The paper concludes with recommendations for the next generation of facilities. 13 refs., 15 figs., 3 tabs.

  9. Thermonuclear Fusion Research Progress and the Way to the Reactor

    NASA Astrophysics Data System (ADS)

    Koch, Raymond

    2006-06-01

    The paper reviews the progress of fusion research and its prospects for electricity generation. It starts with a reminder of the principles of thermonuclear fusion and a brief discussion of its potential role in the future of the world energy production. The reactions allowing energy production by fusion of nuclei in stars and on earth and the conditions required to sustain them are reviewed. At the high temperatures required for fusion (hundred millions kelvins), matter is completely ionized and has reached what is called its 4th state: the plasma state. The possible means to achieve these extreme temperatures is discussed. The remainder of the paper focuses on the most promising of these approaches, magnetic confinement. The operating principles of the presently most efficient machine of this type — the tokamak — is described in some detail. On the road to producing energy with fusion, a number of obstacles have to be overcome. The plasma, a fluid that reacts to electromagnetic forces and carries currents and charges, is a complex medium. Fusion plasma is strongly heated and is therefore a good example of a system far from equilibrium. A wide variety of instabilities can grow in this system and lead to self-organized structures and spontaneous cycles. Turbulence is generated that degrades the confinement and hinders easy achievement of long lasting hot plasmas. Physicists have learned how to quench turbulence, thereby creating sort of insulating bottles inside the plasma itself to circumvent this problem. The recent history of fusion performance is outlined and the prospect of achieving power generation by fusion in a near future is discussed in the light of the development of the "International Tokamak Experimental Reactor" project ITER.

  10. [Human life and energy production. Prospects opened up by controlled thermonuclear fusion].

    PubMed

    Escande, D

    1997-03-18

    The massive and presently increasing energy production is going to confront mankind with a very important problem in the forthcoming decades, in particular due to the vanishing of resources and to the greenhouse effect. The share of fossil fuels in the energy production will have to decrease, and other energy sources will be needed. Among them controlled thermonuclear fusion has may assets due to its non-radioactive fuel with plentiful supply, its non radioactive and non polluting ashes, its safety, its weak environmental impact, and its irrelevance to nuclear proliferation in a normal setting. During the last three decades, physicists have made a series of steps toward the peaceful use of the dominant source of energy in the Universe. They have learned how to confine by magnetic fields plasmas at temperatures of 200 millions degrees centigrade, and they have developed several specific technologies. This way, they produced 11 million watts of nuclear power by fusing two isotopes of hydrogen. These investigations are conducted in a responsible spirit, that of ecoproduction, where possible negative consequences are anticipated, are made as low as reasonably achievable, and their management is studied. Yet several fundamental issues still have to be solved before on economically efficient industrial thermonuclear power plant be operated. A huge international collaboration involving Japan, the USA, the Russian Federation, and the European Union joined with Switzerland and Canada, is presently designing the first experimental thermonuclear reactor, the International Thermonuclear Experimental Reactor (ITER). It would cost 9 billion dollars, a cost similar to other large scientific projects. This is an important step toward an electricity producing thermonuclear reactor that would be both safe and respectful of human health and of environment. PMID:9203740

  11. [Human life and energy production. Prospects opened up by controlled thermonuclear fusion].

    PubMed

    Escande, D

    1997-03-18

    The massive and presently increasing energy production is going to confront mankind with a very important problem in the forthcoming decades, in particular due to the vanishing of resources and to the greenhouse effect. The share of fossil fuels in the energy production will have to decrease, and other energy sources will be needed. Among them controlled thermonuclear fusion has may assets due to its non-radioactive fuel with plentiful supply, its non radioactive and non polluting ashes, its safety, its weak environmental impact, and its irrelevance to nuclear proliferation in a normal setting. During the last three decades, physicists have made a series of steps toward the peaceful use of the dominant source of energy in the Universe. They have learned how to confine by magnetic fields plasmas at temperatures of 200 millions degrees centigrade, and they have developed several specific technologies. This way, they produced 11 million watts of nuclear power by fusing two isotopes of hydrogen. These investigations are conducted in a responsible spirit, that of ecoproduction, where possible negative consequences are anticipated, are made as low as reasonably achievable, and their management is studied. Yet several fundamental issues still have to be solved before on economically efficient industrial thermonuclear power plant be operated. A huge international collaboration involving Japan, the USA, the Russian Federation, and the European Union joined with Switzerland and Canada, is presently designing the first experimental thermonuclear reactor, the International Thermonuclear Experimental Reactor (ITER). It would cost 9 billion dollars, a cost similar to other large scientific projects. This is an important step toward an electricity producing thermonuclear reactor that would be both safe and respectful of human health and of environment.

  12. Method of achieving the controlled release of thermonuclear energy

    DOEpatents

    Brueckner, Keith A.

    1986-01-01

    A method of achieving the controlled release of thermonuclear energy by illuminating a minute, solid density, hollow shell of a mixture of material such as deuterium and tritium with a high intensity, uniformly converging laser wave to effect an extremely rapid build-up of energy in inwardly traveling shock waves to implode the shell creating thermonuclear conditions causing a reaction of deuterons and tritons and a resultant high energy thermonuclear burn. Utilizing the resulting energy as a thermal source and to breed tritium or plutonium. The invention also contemplates a laser source wherein the flux level is increased with time to reduce the initial shock heating of fuel and provide maximum compression after implosion; and, in addition, computations and an equation are provided to enable the selection of a design having a high degree of stability and a dependable fusion performance by establishing a proper relationship between the laser energy input and the size and character of the selected material for the fusion capsule.

  13. Thermonuclear inverse magnetic pumping power cycle for stellarator reactor

    DOEpatents

    Ho, Darwin D.; Kulsrud, Russell M.

    1991-01-01

    The plasma column in a stellarator is compressed and expanded alternatively in minor radius. First a plasma in thermal balance is compressed adiabatically. The volume of the compressed plasma is maintained until the plasma reaches a new thermal equilibrium. The plasma is then expanded to its original volume. As a result of the way a stellarator works, the plasma pressure during compression is less than the corresponding pressure during expansion. Therefore, negative work is done on the plasma over a complete cycle. This work manifests itself as a back-voltage in the toroidal field coils. Direct electrical energy is obtained from this voltage. Alternatively, after the compression step, the plasma can be expanded at constant pressure. The cycle can be made self-sustaining by operating a system of two stellarator reactors in tandem. Part of the energy derived from the expansion phase of a first stellarator reactor is used to compress the plasma in a second stellarator reactor.

  14. The use of idle equipment for ITER (International Thermonuclear Engineering Reactor) magnet development

    SciTech Connect

    Miller, J.R.

    1988-07-11

    Test facilities that can be effectively applied to International Thermonuclear Engineering Reactor (ITER) magnet needs are scarce because the costs and the time required to produce them from the ground up tend to be prohibitive. It has been proposed as an option that several unique and valuable pieces of equipment that are already owned by the DOE be consolidated into the Lawrence Livermore National High Field Test Facility (HFTF) which may be uniquely qualified to make effective use of them. 6 figs., 4 tabs.

  15. Pilot experiments for the International Thermonuclear Experimental Reactor active beam spectroscopy diagnostic

    NASA Astrophysics Data System (ADS)

    Hellermann, M. von; Bock, M. de; Jaspers, R.; Jakubowska, K.; Barnsley, R.; Giroud, C.; Hawkes, N. C.; Zastrow, K. D.; Lotte, P.; Giannella, R.; Malaquias, A.; Rachlew, E.; Tugarinov, S.; Krasilnikov, A.; Litnovsky, A.; Philipps, V.; Wienhold, P.; Oelhafen, P.; Temmerman, G. De; Shmaenok, L.

    2004-10-01

    Supporting pilot experiments and activities which are currently considered or already performed for the development of the International Thermonuclear Experiment Reactor active beam spectroscopy diagnostic are addressed in this article. Four key issues are presented including optimization of spectral instrumentation, feasibility of a motional Stark effect (MSE) evaluation based on line ratios, "first-mirror" test-bed experiments at the tokamak TEXTOR, and finally the role of integrated data analysis for the conceptual layout of the change exchange recombination spectroscopy and MSE diagnostic.

  16. The development and the tests of the electrostatic probe for dust particle collection in thermonuclear reactors

    NASA Astrophysics Data System (ADS)

    Begrambekov, L. B.; Voityuk, A. N.; Zakharov, A. M.

    2016-09-01

    Formation of dust particles in thermonuclear reactors can greatly affect the plasma parameters and lead to accumulation of tritium. The rates of formation and deposition of dust need to be measured, and the parameters of formation of dust particles and clusters need to be studied. A model of a device for collection of fine conductive particles capable of removing them from the reactor chamber for future research is proposed in this paper. The dust collector's operation is based on a principle of applied electrostatic field. The model was tested in different operating conditions: in vacuum, at the atmospheric pressure in the atmosphere of air and dry nitrogen. The experiments were conducted with a stationary system and with the dust collector in motion relative to the dusty surface. It is shown that, during the probe moving relative to the surface, it can remove up to 95% of fine tungsten particles with sizes ranging from 1 to 10 μm.

  17. REACTOR CONTROL

    DOEpatents

    Fortescue, P.; Nicoll, D.

    1962-04-24

    A control system employed with a high pressure gas cooled reactor in which a control rod is positioned for upward and downward movement into the neutron field from a position beneath the reactor is described. The control rod is positioned by a coupled piston cylinder releasably coupled to a power drive means and the pressurized coolant is directed against the lower side of the piston. The coolant pressure is offset by a higher fiuid pressure applied to the upper surface of the piston and means are provided for releasing the higher pressure on the upper side of the piston so that the pressure of the coolant drives the piston upwardly, forcing the coupled control rod into the ncutron field of the reactor. (AEC)

  18. Magnetohydrodynamic-calibrated edge-localized mode model in simulations of International Thermonuclear Experimental Reactor

    NASA Astrophysics Data System (ADS)

    Onjun, Thawatchai; Kritz, Arnold H.; Bateman, Glenn; Parail, Vassili

    2005-08-01

    Self-consistent simulations of the International Thermonuclear Experimental Reactor (ITER) [R. Aymar, P. Barabaschi, and Y. Shimomura, Plasma Phys. Controlled Fusion 44, 519 (2002)] have been carried out using the JETTO-integrated modeling code in which theory-motivated models are used for the H-mode pedestal and for the stability conditions that lead to the edge-localized mode (ELM) crashes. Transport is described by combining the anomalous mixed Bohm/gyro-Bohm model [M. Erba, A. Cherubini, V. V. Parail, and A. Taroni, Plasma Phys. Controlled Fusion 39, 261 (1997)] with the NCLASS neoclassical transport model [W. A. Houlberg, K. C. Shaing, S. P. Hirshman, and M. C. Zarnstorff, Phys. Plasmas 4, 3231 (1997)] in the core region, while only neoclassical transport is used in the pedestal region. In the simulations, an ELM crash can be triggered either by a pressure-driven ballooning mode or by a current-driven peeling mode, depending on which instability reaches its stability criterion first. The equilibrium and magnetohydrodynamics (MHD) stability analyses codes, HELENA and MISHKA [A. B. Mikhailovskii, G. T. A. Huysmans, S. E. Sharapov, and W. Kerner, Plasma Phys. Rep. 23, 713 (1997)], are used to evaluate the edge stability of the plasma just prior to an ELM crash in order to calibrate and confirm the validity of the stability criteria used to trigger ELMs in the JETTO simulations. It is found that the simulation of the ITER baseline case yields a fusion Q of 16.6, with the electron and ion temperatures at the top of the pedestal of 4.4 and 4.9keV, respectively. The high values of the pedestal temperature result from access to the second stability region of the ballooning mode. Simulation sensitivity studies are carried out by varying parameters such as the auxiliary heating power and the width of the pedestal. When the auxiliary heating power is turned off, it is found that significant fusion power is sustained and that access to ballooning mode second stability is

  19. Review of the International Thermonuclear Experimental Reactor (ITER) detailed design report

    SciTech Connect

    1997-04-18

    Dr. Martha Krebs, Director, Office of Energy Research at the US Department of Energy (DOE), wrote to the Fusion Energy Sciences Advisory Committee (FESAC), in letters dated September 23 and November 6, 1996, requesting that FESAC review the International Thermonuclear Experimental Reactor (ITER) Detailed Design Report (DDR) and provide its view of the adequacy of the DDR as part of the basis for the United States decision to enter negotiations with the other interested Parties regarding the terms and conditions for an agreement for the construction, operations, exploitation and decommissioning of ITER. The letter from Dr. Krebs, referred to as the Charge Letter, provided context for the review and a set of questions of specific interest.

  20. The development of beryllium plasma spray technology for the International Thermonuclear Experimental Reactor (ITER)

    SciTech Connect

    Castro, R.G.; Elliott, K.E.; Hollis, K.J.; Bartlett, A.H.; Watson, R.D.

    1999-02-01

    Over the past five years, four international parties, which include the European Communities, Japan, the Russian Federation and the United States, have been collaborating on the design and development of the International Thermonuclear Experimental Reactor (ITER), the next generation magnetic fusion energy device. During the ITER Engineering Design Activity (EDA), beryllium plasma spray technology was investigated by Los Alamos National Laboratory as a method for fabricating and repairing and the beryllium first wall surface of the ITER tokamak. Significant progress has been made in developing beryllium plasma spraying technology for this application. Information will be presented on the research performed to improve the thermal properties of plasma sprayed beryllium coatings and a method that was developed for cleaning and preparing the surface of beryllium prior to depositing plasma sprayed beryllium coatings. Results of high heat flux testing of the beryllium coatings using electron beam simulated ITER conditions will also be presented.

  1. REACTOR CONTROL

    DOEpatents

    Ruano, W.J.

    1957-12-10

    This patent relates to nuclear reactors of the type which utilize elongited rod type fuel elements immersed in a liquid moderator and shows a design whereby control of the chain reaction is obtained by varying the amount of moderator or reflector material. A central tank for containing liquid moderator and fuel elements immersed therein is disposed within a surrounding outer tank providing an annular space between the two tanks. This annular space is filled with liquid moderator which functions as a reflector to reflect neutrons back into the central reactor tank to increase the reproduction ratio. Means are provided for circulating and cooling the moderator material in both tanks and additional means are provided for controlling separately the volume of moderator in each tank, which latter means may be operated automatically by a neutron density monitoring device. The patent also shows an arrangement for controlling the chain reaction by injecting and varying an amount of poisoning material in the moderator used in the reflector portion of the reactor.

  2. Thermonuclear land of plenty

    NASA Astrophysics Data System (ADS)

    Gasior, P.

    2014-11-01

    Since the process of energy production in the stars has been identified as the thermonuclear fusion, this mechanism has been proclaimed as a future, extremely modern, reliable and safe for sustaining energetic needs of the humankind. However, the idea itself was rather straightforward and the first attempts to harness thermonuclear reactions have been taken yet in 40s of the twentieth century, it quickly appeared that physical and technical problems of domesticating exotic high temperature medium known as plasma are far from being trivial. Though technical developments as lasers, superconductors or advanced semiconductor electronics and computers gave significant contribution for the development of the thermonuclear fusion reactors, for a very long time their efficient performance was out of reach of technology. Years of the scientific progress brought the conclusions that for the development of the thermonuclear power plants an enormous interdisciplinary effort is needed in many fields of science covering not only plasma physics but also material research, superconductors, lasers, advanced diagnostic systems (e.g. spectroscopy, interferometry, scattering techniques, etc.) with huge amounts of data to be processed, cryogenics, measurement-control systems, automatics, robotics, nanotechnology, etc. Due to the sophistication of the problems with plasma control and plasma material interactions only such a combination of the research effort can give a positive output which can assure the energy needs of our civilization. In this paper the problems of thermonuclear technology are briefly outlined and it is shown why this domain can be a broad field for the experts dealing with electronics, optoelectronics, programming and numerical simulations, who at first glance can have nothing common with the plasma or nuclear physics.

  3. Economic impacts on the United States of siting decisions for the international thermonuclear experimental reactor

    SciTech Connect

    Peerenboom, J.P.; Hanson, M.E.; Huddleston, J.R.

    1996-08-01

    This report presents the results of a study that examines and compares the probable short-term economic impacts of the International Thermonuclear Experimental Reactor (ITER) on the United States (U.S.) if (1) ITER were to be sited in the U.S., or (2) ITER were to be sited in one of the other countries that, along with the U.S., is currently participating in the ITER program. Life-cycle costs associated with ITER construction, operation, and decommissioning are analyzed to assess their economic impact. A number of possible U.S. host and U.S. non-host technology and cost-sharing arrangements with the other ITER Parties are examined, although cost-sharing arrangements and the process by which the Parties will select a host country and an ITER site remain open issues. Both national and local/regional economic impacts, as measured by gross domestic product, regional output, employment, net exports, and income, are considered. These impacts represent a portion of the complex, interrelated set of economic considerations that characterize U.S. host and U.S. non-host participation in ITER. A number of other potentially important economic and noneconomic considerations are discussed qualitatively.

  4. Recommendations for a cryogenic system for ITER (International Thermonuclear Experimental Reactor)

    SciTech Connect

    Slack, D.S.

    1989-09-20

    The International Thermonuclear Experimental Reactor (ITER) is a new tokamak design project with joint participation from Japan, the European Community, the Soviet Union, and the United States. ITER will be a large machine requiring up to 100 kW of refrigeration at 4.5 K to cool its superconducting magnets. Unlike earlier fusion experiments, the ITER cryogenic system must handle pulse loads constituting a large percentage of the total load. These come from neutron heating during a fusion burn and from ac losses during ramping of current in the PF (poloidal field) coils. This paper presents a conceptual design for a cryogenic system that meets ITER requirements. It describes a system with the following features: Only time-proven components are used. The system obtains a high efficiency without use of cold pumps or other developmental components. High reliability is achieved by paralleling compressors and expanders and by using adequate isolation valving. The problem of load fluctuations is solved by a simple load-leveling device. The cryogenic system can be housed in a separate building located at a considerable distance from the ITER core, if desired. The paper also summarizes physical plant size, cost estimates, and means of handling vented helium during magnet quench. 4 refs., 4 figs., 3 tabs.

  5. Design considerations for ITER (International Thermonuclear Experimental Reactor) toroidal field coils

    SciTech Connect

    Kalsi, S.S.; Lousteau, D.C.; Miller, J.R.

    1987-01-01

    The International Thermonuclear Experimental Reactor (ITER) is a new tokamak design project with joint participation from Europe, Japan, the Union of Soviet Socialist Republics (USSR), and the United States. This paper describes a magnetic and mechanical design methodology for toroidal field (TF) coils that employs Nb/sub 3/Sn superconductor technology. Coil winding is sized by using conductor concepts developed for the US TIBER concept. The nuclear heating generated during operation is removed from the windings by helium flowing through the conductor. The heat in the coil case is removed through a separate cooling circuit operating at approximately 20 K. Manifold concepts are presented for the complete coil cooling system. Also included are concepts for the coil structural arrangement. The effects of in-plane and out-of-plane loads are included in the design considerations for the windings and case. Concepts are presented for reacting these loads with a minimum amount of additional structural material. Concepts discussed in this paper could be considered for the ITER TF coils. 6 refs., 5 figs., 1 tab.

  6. Antenna design for fast ion collective Thomson scattering diagnostic for the international thermonuclear experimental reactor.

    PubMed

    Leipold, F; Furtula, V; Salewski, M; Bindslev, H; Korsholm, S B; Meo, F; Michelsen, P K; Moseev, D; Nielsen, S K; Stejner, M

    2009-09-01

    Fast ion physics will play an important role for the international thermonuclear experimental reactor (ITER), where confined alpha particles will affect and be affected by plasma dynamics and thereby have impacts on the overall confinement. A fast ion collective Thomson scattering (CTS) diagnostic using gyrotrons operated at 60 GHz will meet the requirements for spatially and temporally resolved measurements of the velocity distributions of confined fast alphas in ITER by evaluating the scattered radiation (CTS signal). While a receiver antenna on the low field side of the tokamak, resolving near perpendicular (to the magnetic field) velocity components, has been enabled, an additional antenna on the high field side (HFS) would enable measurements of near parallel (to the magnetic field) velocity components. A compact design solution for the proposed mirror system on the HFS is presented. The HFS CTS antenna is located behind the blankets and views the plasma through the gap between two blanket modules. The viewing gap has been modified to dimensions 30x500 mm(2) to optimize the CTS signal. A 1:1 mock-up of the HFS mirror system was built. Measurements of the beam characteristics for millimeter-waves at 60 GHz used in the mock-up agree well with the modeling.

  7. Bulk-bronzied graphites for plasma-facing components in ITER (International Thermonuclear Experimental Reactor)

    SciTech Connect

    Hirooka, Y.; Conn, R.W.; Doerner, R.; Khandagle, M. . Inst. of Plasma and Fusion Research); Causey, R.; Wilson, K. ); Croessmann, D.; Whitley, J. ); Holland, D.; Smolik, G. ); Matsuda, T.; Sogabe, T. (Toyo Tanso Co. Ltd., O

    1990-06-01

    Newly developed bulk-boronized graphites and boronized C-C composites with a total boron concentration ranging from 1 wt % to 30 wt % have been evaluated as plasma-facing component materials for the International Thermonuclear Experimental Reactor (ITER). Bulk-boronized graphites have been bombarded with high-flux deuterium plasmas at temperatures between 200 and 1600{degree}C. Plasma interaction induced erosion of bulk-boronized graphites is observed to be a factor of 2--3 smaller than that of pyrolytic graphite, in regimes of physical sputtering, chemical sputtering and radiation enhanced sublimation. Postbombardment thermal desorption spectroscopy indicates that bulk-boronized graphites enhance recombinative desorption of deuterium, which leads to a suppression of the formation of deuterocarbon due to chemical sputtering. The tritium inventory in graphite has been found to decrease by an order of magnitude due to 10 wt % bulk-boronization at temperatures above 1000{degree}C. The critical heat flux to induce cracking for bulk-boronized graphites has been found to be essentially the same as that for non-boronized graphites. Also, 10 wt % bulk-boronization of graphite hinders air oxidation nearly completely at 800{degree}C and reduces the steam oxidation rate by a factor of 2--3 at around 1100 and 1350{degree}C. 38 refs., 5 figs.

  8. Development of multifilamentary niobium titanium and niobium tin strands for the International Thermonuclear Experimental Reactor project

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Zhang, P. X.; Tang, X. D.; Liu, X. H.; Lu, Y. F.; Weng, P. D.; Grunblatt, G.; Hoang, Gia K.; Verwaerde, C.

    2007-05-01

    The International Thermonuclear Experimental Reactor(ITER) device should demonstrate the scientific and technological possibility of commercial fusion energy production in large scale in order to solve the worldwide energy problem in the future. The superconducting magnet system is the key part of the ITER device to supply high magnetic fields for confining the deuterium-tritium plasma. The multifilament NbTi and Nb3Sn strands with high quality have been studied to meet the specifications of superconducting strands for fabricating poloidal field coils (PF) and toroidal field coils (TF). For NbTi strands with 8306 filaments, Jc of 2910 A mm-2 (4.2 K, 5 T, 0.1 μV cm-1) has been obtained by a conventional process. The proposed process could be used for fabrication of long strands with a unit length more than 5000 m. By an internal tin process the multifilamentary Nb3Sn strands with a diameter of 0.79 mm and a unit length longer than 5000 m have been successfully fabricated. The highest non-Cu Jcn (12 T, 4.2 K, 0.1 μV cm-1) value of 1249 A mm-2 has been obtained. The n-value of Nb3Sn strands is larger than 20 and the residual resistance ratio (RRR) value lies between 150 and 220. The formation of the Nb3Sn superconducting phase together with the evolution of microstructure has been investigated by neutron diffraction and scanning electron microscopy. The results indicate that the properties of NbTi and Nb3Sn strands have already met basically the specifications proposed by the ITER program.

  9. Transmission thermography for inspecting the busbar insulation layer in thermonuclear experimental reactor

    NASA Astrophysics Data System (ADS)

    Chen, Dapeng; Zhang, Guang; Zhang, Xiaolong; Zeng, Zhi

    2014-11-01

    In Thermonuclear Experimental Reactor, Superconducting Busbar is used for current transmission between magnet coils and current leads. The work temperature of the Busbar is about 4K because of liquid helium via inside. The large temperature grad from 300K to 4K could lead to the defects and damages occur on the insulation layer, which is made of glass fiber and polyimide and has a big different thermal expansion coefficient compared with the metal inner cylinder. This paper aims at developing an infrared transmission non-destructive evaluation (NDE) method for inspecting the insulation layer of Superconducting Busbar; theoretical model of transient heat conduction under a continuous inner heat source for cylindrical structure is described in the paper; a Busbar specimen which is designed with three delamination defects of different depths is heated inside by pouring hot water and monitored by an infrared detector located outside. Results demonstrate excellent detection performance for delamination defects in the insulation layer by using transmission thermography, all of the three defects of different depths can be visualized clearly in the thermal images, and the deeper defect has a better signal contrast, which is also shown in the temperature difference between defects and sound area vs. time curves. The results of light pulse thermography is also shown as a comparison, and it is found that the thermal images obtained by the transmission thermography has a much better signal contrast than that of the pulse thermography. In order to verify the experiments, finite element method is applied to simulate the heat conduction in the Busbar under the continuous inside heating, and it is found that the simulated temperature vs. time and simulated temperature difference vs. time curves are basically coincident with the experimental results. In addition, the possibility of in-service inspection for Busbar insulation layer in ITER item is discussed.

  10. Control Means for Reactor

    DOEpatents

    Manley, J. H.

    1961-06-27

    An apparatus for controlling a nuclear reactor includes a tank just below the reactor, tubes extending from the tank into the reactor, and a thermally expansible liquid neutron absorbent material in the tank. The liquid in the tank is exposed to a beam of neutrons from the reactor which heats the liquid causing it to expand into the reactor when the neutron flux in the reactor rises above a predetermincd danger point. Boron triamine may be used for this purpose.

  11. Ion species mix measurements in DIII-D and International Thermonuclear Experimental Reactor using ion-ion hybrid layer reflectometry

    SciTech Connect

    Heidbrink, W.W.; Watson, G.W.; Burrell, K.H.

    2004-10-01

    A superheterodyne reflectometer can provide a direct and inexpensive measurement of the concentrations of ion species with different charge to mass ratios. The ion-ion hybrid cutoff frequency is uniquely determined by the cyclotron frequencies and concentrations of the different species. The phase of a {approx}20 MHz wave that travels from a launching antenna on the low-field side of a tokamak, reflects off the cutoff layer, then travels to a receiving antenna provides a direct measure of the species mix. Hydrogen concentrations between 3% and 67% are measured in DIII-D using this technique. In theory, the technique can measure the spatial profile of the tritium concentration in the International Thermonuclear Experimental Reactor. Possible practical difficulties include attenuation of the wave in the evanescent layer near the antenna.

  12. NUCLEAR REACTOR CONTROL SYSTEM

    DOEpatents

    Epler, E.P.; Hanauer, S.H.; Oakes, L.C.

    1959-11-01

    A control system is described for a nuclear reactor using enriched uranium fuel of the type of the swimming pool and other heterogeneous nuclear reactors. Circuits are included for automatically removing and inserting the control rods during the course of normal operation. Appropriate safety circuits close down the nuclear reactor in the event of emergency.

  13. Mechanical tests of the conduit tubes of a conductor for the Toroidal winding of the International Thermonuclear Experimental Reactor (ITER)

    NASA Astrophysics Data System (ADS)

    Krivykh, A. V.; Anashkin, O. P.; Keilin, V. E.; Diev, D. N.; Dinisilov, A. S.; Shcherbakov, V. I.; Tronza, V. I.

    2012-11-01

    Extremely stringent requirements, which include the impact toughness at the liquid-helium temperature, are imposed on the material of the conduit tubes for International Thermonuclear Experimental Reactor (ITER) Toroidal Field (TF) conductors. Modified 316LN-IG stainless steel is recommended as the conduit tube material. Steel 316LN-IG tube samples (both full-size samples and sub-sized samples) are subjected to mechanical tests at various stages of the process of conductor production: in the as-recieved state and after compacting, preliminary elongation by 2.5% at room temperature, and annealing at 650°C for 200 h in a pure helium gas atmosphere. The tests are carried out at room, liquid nitrogen, and liquid helium temperatures and satisfy the standards of the American Society of Mechanical Engineers (ASME and ASTM). The results of sub-size and full-size samples testing show that the last one gives more representative results to qualify the weld joints in liquid nitrogen. When the temperature decreases or the strain increases, the magnetization of the samples increases, especially in the weld area. Strain measurements with an extensometer demonstrate that the intracrystal processes occurring at the liquid-helium temperature can lead to a significant change in the local load, up to complete unloading in a deformation zone. Unusual local serrated deformation is observed with an extensometer installed in the weld area during tests in liquid helium: this deformation is the result of compressive jumps opposite to the loading direction.

  14. Annual report of the Summit Members' Working Group on Controlled Thermonuclear Fusion (Fusin Working Group (FWG))

    SciTech Connect

    none,

    1987-04-01

    The Summit Members' Working Group on Controlled Thermonuclear Fusion (Fusion Working Group (FWG)) was established in 1983 in response to the Declaration of the Heads of State and Government at the Versailles Economic Summit meeting of 1982, and in response to the subsequent report of the Working Group in Technology, Growth and Employment (TGE) as endorsed at the Williamsburg Summit meeting, 1983. This document contains the complete written record of each of the three FWG meetings which include the minutes, lists of attendees, agendas, statements, and summary conclusions as well as the full reports of the Technical Working Party. In addition, there is a pertinent exchange of correspondence between FWG members on the role of the Technical Working Party and a requested background paper on the modalities associated with a possible future ETR project.

  15. CONTROL FOR NEUTRONIC REACTOR

    DOEpatents

    Lichtenberger, H.V.; Cameron, R.A.

    1959-03-31

    S>A control rod operating device in a nuclear reactor of the type in which the control rod is gradually withdrawn from the reactor to a position desired during stable operation is described. The apparatus is comprised essentially of a stop member movable in the direction of withdrawal of the control rod, a follower on the control rod engageable with the stop and means urging the follower against the stop in the direction of withdrawal. A means responsive to disengagement of the follower from the stop is provided for actuating the control rod to return to the reactor shut-down position.

  16. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Dreffin, R.S.

    1959-12-15

    A control means for a nuclear reactor is described. Particularly a device extending into the active portion of the reactor consisting of two hollow elements coaxially disposed and forming a channel therebetween, the cross sectional area of the channel increasing from each extremity of the device towards the center thereof. An element of neutron absorbing material is slidably positionable within the inner hollow element and a fluid reactor poison is introduced into the channel defined by the two hollow elements.

  17. Effect of particle pinch on the fusion performance and profile features of an international thermonuclear experimental reactor-like fusion reactor

    NASA Astrophysics Data System (ADS)

    Wang, Shijia; Wang, Shaojie

    2015-04-01

    The evolution of the plasma temperature and density in an international thermonuclear experimental reactor (ITER)-like fusion device has been studied by numerically solving the energy transport equation coupled with the particle transport equation. The effect of particle pinch, which depends on the magnetic curvature and the safety factor, has been taken into account. The plasma is primarily heated by the alpha particles which are produced by the deuterium-tritium fusion reactions. A semi-empirical method, which adopts the ITERH-98P(y,2) scaling law, has been used to evaluate the transport coefficients. The fusion performances (the fusion energy gain factor, Q) similar to the ITER inductive scenario and non-inductive scenario (with reversed magnetic shear) are obtained. It is shown that the particle pinch has significant effects on the fusion performance and profiles of a fusion reactor. When the volume-averaged density is fixed, particle pinch can lower the pedestal density by ˜30 % , with the Q value and the central pressure almost unchanged. When the particle source or the pedestal density is fixed, the particle pinch can significantly enhance the Q value by 60 % , with the central pressure also significantly raised.

  18. Effect of particle pinch on the fusion performance and profile features of an international thermonuclear experimental reactor-like fusion reactor

    SciTech Connect

    Wang, Shijia Wang, Shaojie

    2015-04-15

    The evolution of the plasma temperature and density in an international thermonuclear experimental reactor (ITER)-like fusion device has been studied by numerically solving the energy transport equation coupled with the particle transport equation. The effect of particle pinch, which depends on the magnetic curvature and the safety factor, has been taken into account. The plasma is primarily heated by the alpha particles which are produced by the deuterium-tritium fusion reactions. A semi-empirical method, which adopts the ITERH-98P(y,2) scaling law, has been used to evaluate the transport coefficients. The fusion performances (the fusion energy gain factor, Q) similar to the ITER inductive scenario and non-inductive scenario (with reversed magnetic shear) are obtained. It is shown that the particle pinch has significant effects on the fusion performance and profiles of a fusion reactor. When the volume-averaged density is fixed, particle pinch can lower the pedestal density by ∼30%, with the Q value and the central pressure almost unchanged. When the particle source or the pedestal density is fixed, the particle pinch can significantly enhance the Q value by  60%, with the central pressure also significantly raised.

  19. Nuclear reactor control column

    DOEpatents

    Bachovchin, Dennis M.

    1982-01-01

    The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest cross-sectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor.

  20. REACTOR CONTROL SYSTEM

    DOEpatents

    MacNeill, J.H.; Estabrook, J.Y.

    1960-05-10

    A reactor control system including a continuous tape passing through a first coolant passageway, over idler rollers, back through another parallel passageway, and over motor-driven rollers is described. Discrete portions of fuel or poison are carried on two opposed active sections of the tape. Driving the tape in forward or reverse directions causes both active sections to be simultaneously inserted or withdrawn uniformly, tending to maintain a more uniform flux within the reactor. The system is particularly useful in mobile reactors, where reduced inertial resistance to control rod movement is important.

  1. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Metcalf, H.E.

    1958-10-14

    Methods of controlling reactors are presented. Specifically, a plurality of neutron absorber members are adjustably disposed in the reactor core at different distances from the center thereof. The absorber members extend into the core from opposite faces thereof and are operated by motive means coupled in a manner to simultaneously withdraw at least one of the absorber members while inserting one of the other absorber members. This feature effects fine control of the neutron reproduction ratio by varying the total volume of the reactor effective in developing the neutronic reaction.

  2. Method and system to directly produce electrical power within the lithium blanket region of a magnetically confined, deuterium-tritium (DT) fueled, thermonuclear fusion reactor

    DOEpatents

    Woolley, Robert D.

    1999-01-01

    A method for integrating liquid metal magnetohydrodynamic power generation with fusion blanket technology to produce electrical power from a thermonuclear fusion reactor located within a confining magnetic field and within a toroidal structure. A hot liquid metal flows from a liquid metal blanket region into a pump duct of an electromagnetic pump which moves the liquid metal to a mixer where a gas of predetermined pressure is mixed with the pressurized liquid metal to form a Froth mixture. Electrical power is generated by flowing the Froth mixture between electrodes in a generator duct. When the Froth mixture exits the generator the gas is separated from the liquid metal and both are recycled.

  3. Method and System to Directly Produce Electrical Power within the Lithium Blanket Region of a Magnetically Confined, Deuterium-Tritium (DT) Fueled, Thermonuclear Fusion Reactor

    SciTech Connect

    Woolley, Robert D.

    1998-09-22

    A method for integrating liquid metal magnetohydrodynamic power generation with fusion blanket technology to produce electrical power from a thermonuclear fusion reactor located within a confining magnetic field and within a toroidal structure. A hot liquid metal flows from a liquid metal blanket region into a pump duct of an electromagnetic pump which moves the liquid metal to a mixer where a gas of predetermined pressure is mixed with the pressurized liquid metal to form a Froth mixture. Electrical power is generated by flowing the Froth mixture between electrodes in a generator duct. When the Froth mixture exits the generator the gas is separated from the liquid metal and both are recycled.

  4. Progress in preparing scenarios for operation of the International Thermonuclear Experimental Reactor

    NASA Astrophysics Data System (ADS)

    Sips, A. C. C.; Giruzzi, G.; Ide, S.; Kessel, C.; Luce, T. C.; Snipes, J. A.; Stober, J. K.

    2015-02-01

    -mode operation in helium may be possible at input powers above 35 MW at a toroidal field of 2.65 T, for studying H-modes and ELM mitigation. In hydrogen, H-mode operation is expected to be marginal, even at 2.65 T with 60 MW of input power. Simulation code benchmark studies using hybrid and steady state scenario parameters have proved to be a very challenging and lengthy task of testing suites of codes, consisting of tens of sophisticated modules. Nevertheless, the general basis of the modelling appears sound, with substantial consistency among codes developed by different groups. For a hybrid scenario at 12 MA, the code simulations give a range for Q = 6.5-8.3, using 30 MW neutral beam injection and 20 MW ICRH. For non-inductive operation at 7-9 MA, the simulation results show more variation. At high edge pedestal pressure (Tped ˜ 7 keV), the codes predict Q = 3.3-3.8 using 33 MW NB, 20 MW EC, and 20 MW ion cyclotron to demonstrate the feasibility of steady-state operation with the day-1 heating systems in ITER. Simulations using a lower edge pedestal temperature (˜3 keV) but improved core confinement obtain Q = 5-6.5, when ECCD is concentrated at mid-radius and ˜20 MW off-axis current drive (ECCD or LHCD) is added. Several issues remain to be studied, including plasmas with dominant electron heating, mitigation of transient heat loads integrated in scenario demonstrations and (burn) control simulations in ITER scenarios.

  5. Progress in preparing scenarios for operation of the International Thermonuclear Experimental Reactor

    SciTech Connect

    Sips, A. C. C.; Giruzzi, G.; Ide, S.; Kessel, C.; Luce, T. C.; Snipes, J. A.; Stober, J. K.

    2015-02-15

    in hydrogen and helium requires high input power (>50 MW). H-mode operation in helium may be possible at input powers above 35 MW at a toroidal field of 2.65 T, for studying H-modes and ELM mitigation. In hydrogen, H-mode operation is expected to be marginal, even at 2.65 T with 60 MW of input power. Simulation code benchmark studies using hybrid and steady state scenario parameters have proved to be a very challenging and lengthy task of testing suites of codes, consisting of tens of sophisticated modules. Nevertheless, the general basis of the modelling appears sound, with substantial consistency among codes developed by different groups. For a hybrid scenario at 12 MA, the code simulations give a range for Q = 6.5–8.3, using 30 MW neutral beam injection and 20 MW ICRH. For non-inductive operation at 7–9 MA, the simulation results show more variation. At high edge pedestal pressure (T{sub ped} ∼ 7 keV), the codes predict Q = 3.3–3.8 using 33 MW NB, 20 MW EC, and 20 MW ion cyclotron to demonstrate the feasibility of steady-state operation with the day-1 heating systems in ITER. Simulations using a lower edge pedestal temperature (∼3 keV) but improved core confinement obtain Q = 5–6.5, when ECCD is concentrated at mid-radius and ∼20 MW off-axis current drive (ECCD or LHCD) is added. Several issues remain to be studied, including plasmas with dominant electron heating, mitigation of transient heat loads integrated in scenario demonstrations and (burn) control simulations in ITER scenarios.

  6. NEUTRONIC REACTOR CONTROL ELEMENT

    DOEpatents

    Newson, H.W.

    1960-09-13

    A novel composite neutronic reactor control element is offered. The element comprises a multiplicity of sections arranged in end-to-end relationship, each of the sections having a markedly different neutron-reactive characteristic. For example, a three-section control element could contain absorber, moderator, and fuel sections. By moving such an element longitudinally through a reactor core, reactivity is decreased by the absorber, increased slightly by the moderator, or increased substantially by the fuel. Thus, control over a wide reactivity range is provided.

  7. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Untermyer, S.; Hutter, E.

    1959-08-01

    This patent relates to "shadow" control of a nuclear reactor. The control means comprises a plurality ot elongated rods disposed adjacent and parallel to each other, The morphology and effects of gases generated within sections of neutron absorbing materials and equal length sections of neutron permeable materials together with means for longitudinally pcsitioning the rcds relative to each other.

  8. REACTOR CONTROL DEVICE

    DOEpatents

    Graham, R.H.

    1962-09-01

    A wholly mechanical compact control device is designed for automatically rendering the core of a fission reactor subcritical in response to core temperatures in excess of the design operating temperature limit. The control device comprises an expansible bellows interposed between the base of a channel in a reactor core and the inner end of a fuel cylinder therein which is normally resiliently urged inwardly. The bellows contains a working fluid which undergoes a liquid to vapor phase change at a temperature substantially equal to the design temperature limit. Hence, the bellows abruptiy expands at this limiting temperature to force the fuel cylinder outward and render the core subcritical. The control device is particularly applicable to aircraft propulsion reactor service. (AEC)

  9. Nuclear reactor control apparatus

    DOEpatents

    Sridhar, Bettadapur N.

    1983-11-01

    Nuclear reactor core safety rod release apparatus comprises a control rod having a detent notch in the form of an annular peripheral recess at its upper end, a control rod support tube for raising and lowering the control rod under normal conditions, latches pivotally mounted on the control support tube with free ends thereof normally disposed in the recess in the control rod, and cam means for pivoting the latches out of the recess in the control rod when a scram condition occurs. One embodiment of the invention comprises an additional magnetically-operated latch for releasing the control rod under two different conditions, one involving seismic shock.

  10. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Physics of the plasma corona in the problem of laser controlled thermonuclear fusion

    NASA Astrophysics Data System (ADS)

    Andreev, N. E.; Gorbunov, Leonid M.; Tikhonchuk, Vladimir T.

    1994-09-01

    A brief analysis is made of the most important nonlinear processes which result from the interaction of laser radiation with thermonuclear targets. lt is shown that problems in the physics of the plasma corona should be an essential part of any programme of research on laser controlled thermonuclear fusion. A list is given of the problems that have to be solved first before going to the next level of laser energies.

  11. REACTOR CONTROL DEVICE

    DOEpatents

    Kaufman, H.B.; Weiss, A.A.

    1959-08-18

    A shadow control device for controlling a nuclear reactor is described. The device comprises a series of hollow neutron-absorbing elements arranged in groups, each element having a cavity for substantially housing an adjoining element and a longitudinal member for commonly supporting the groups of elements. Longitudinal actuation of the longitudinal member distributes the elements along its entire length in which position maximum worth is achieved.

  12. Neutron behavior, reactor control, and reactor heat transfer. Volume four

    SciTech Connect

    Not Available

    1986-01-01

    Volume four covers neutron behavior (neutron absorption, how big are nuclei, neutron slowing down, neutron losses, the self-sustaining reactor), reactor control (what is controlled in a reactor, controlling neutron population, is it easy to control a reactor, range of reactor control, what happens when the fuel burns up, controlling a PWR, controlling a BWR, inherent safety of reactors), and reactor heat transfer (heat generation in a nuclear reactor, how is heat removed from a reactor core, heat transfer rate, heat transfer properties of the reactor coolant).

  13. Nuclear reactor control

    DOEpatents

    Cawley, William E.; Warnick, Robert F.

    1982-01-01

    1. In a nuclear reactor incorporating a plurality of columns of tubular fuel elements disposed in horizontal tubes in a mass of graphite wherein water flows through the tubes to cool the fuel elements, the improvement comprising at least one control column disposed in a horizontal tube including fewer fuel elements than in a normal column of fuel elements and tubular control elements disposed at both ends of said control column, and means for varying the horizontal displacement of the control column comprising a winch at the upstream end of the control column and a cable extending through the fuel and control elements and attached to the element at the downstream end of the column.

  14. FENIX (Fusion ENgineering International eXperimental): A test facility for ITER (International Thermonuclear Experimental Reactor) and other new superconducting magnets

    SciTech Connect

    Slack, D.S.; Patrick, R.E.; Miller, J.R.

    1990-09-21

    The Fusion ENgineering International eXperimental (FENIX) Test Facility which is nearing completion at Lawrence Livermore National Laboratory, is a 76-t set of superconducting magnets housed in a 4-m-diameter cryostat. It represents a significant step toward meeting the testing needs for the development of superconductors appropriate for large-scale magnet applications such as the International Thermonuclear Experimental Reactor (ITER). The magnet set is configured to allow radial access to the 0.4-m-diameter high-field region where maximum fields up to 14 T will be provided. The facility is fitted with a thermally isolated test well with a port to the high-field region that allows insertion and removal of test conductors without disturbing the cryogenic environment of the magnets. It is expected that the facility will be made available to magnet developers internationally, and this paper discusses its general design features, its construction, and its capabilities.

  15. NUCLEAR REACTOR CONTROL SYSTEM

    DOEpatents

    Howard, D.F.; Motta, E.E.

    1961-06-27

    A method for controlling the excess reactivity in a nuclear reactor throughout the core life while maintaining the neutron flux distribution at the desired level is described. The control unit embodies a container having two electrodes of different surface area immersed in an electrolytic solution of a good neutron sbsorbing metal ion such as boron, gadolinium, or cadmium. Initially, the neutron absorber is plated on the larger electrode to control the greater neutron flux of a freshly refueled core. As the fuel burns up, the excess reactivity decreases and the neutron absorber is then plated onto the smaller electrode so that the number of neutrons absorbed also decreases. The excess reactivity in the core may thus be maintained without the introduction of serious perturbations in the neutron flux distributibn.

  16. Nuclear Reactor Kinetics and Control.

    SciTech Connect

    JEFFERY,; LEWINS, D.

    2009-07-27

    Version 00 Dr. J.D. Lewins has now released the following legacy book for free distribution: Nuclear Reactor Kinetics and Control, Pergamon Press, London, 275 pages, 1978. 1. Introductory Review 2. Neutron and Precursor Equations 3. Elementary Solutions of the Kinetics Equations at Low Power 4. Linear Reactor Process Dynamics with Feedback 5. Power Reactor Control Systems 6. Fluctuations and Reactor Noise 7. Safety and Reliability 8. Non Linear Systems; Stability and Control 9. Analogue Computing Addendum: Jay Basken and Jeffery D. Lewins: Power Series Solution of the Reactor Kinetics Equations, Nuclear Science and Engineering: 122, 407-436 (1996) (authorized for distribution with the book: courtesy of the American Nuclear Society)

  17. REACTOR CONTROL MECHANISM

    DOEpatents

    Lane, J.A.; Engberg, R.E.; Welch, J.M.

    1959-05-12

    A quick-releasing mechanism is described which may be used to rapidiy drop a device supported from beneath during normal use, such as a safety rod in a nuclear reactor. In accordance with this invention an electrical control signal, such as may be provided by radiation detection or other alarm condition sensing devices, is delivered to an electromagnetic solenoid, the armature of which is coupled to an actuating mechanism. The solenoid is energized when the mechanism is in its upper or cocked position. In such position, the mechanism engages a plurality of retaining balls, forcing them outward into engagement with a shoulder or recess in a corresponding section of a tubular extension on the upheld device. When the control signal to the solenoid suddenly ceases, the armature drops out, allowing the actuating mechanism to move slightly but rapidly under the force of a compressed spring. The weight of the device will urge the balls inward against a beveled portion of the actuating mechanism and away from the engaging section on the tubular extension, thus allowing the upheld device to fall freely under the influence of gravity.

  18. Nuclear Reactor Kinetics and Control.

    2009-07-27

    Version 00 Dr. J.D. Lewins has now released the following legacy book for free distribution: Nuclear Reactor Kinetics and Control, Pergamon Press, London, 275 pages, 1978. 1. Introductory Review 2. Neutron and Precursor Equations 3. Elementary Solutions of the Kinetics Equations at Low Power 4. Linear Reactor Process Dynamics with Feedback 5. Power Reactor Control Systems 6. Fluctuations and Reactor Noise 7. Safety and Reliability 8. Non Linear Systems; Stability and Control 9. Analogue Computingmore » Addendum: Jay Basken and Jeffery D. Lewins: Power Series Solution of the Reactor Kinetics Equations, Nuclear Science and Engineering: 122, 407-436 (1996) (authorized for distribution with the book: courtesy of the American Nuclear Society)« less

  19. REACTOR CONTROL ROD OPERATING SYSTEM

    DOEpatents

    Miller, G.

    1961-12-12

    A nuclear reactor control rod mechanism is designed which mechanically moves the control rods into and out of the core under normal conditions but rapidly forces the control rods into the core by catapultic action in the event of an emergency. (AEC)

  20. Reactor control rod timing system

    DOEpatents

    Wu, Peter T. K.

    1982-01-01

    A fluid driven jet-edge whistle timing system for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

  1. Reactor control rod timing system

    SciTech Connect

    Wu, P.T.

    1982-02-09

    A fluid driven jet-edge whistle timing system for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (Above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

  2. Development of a Jones vector based model for the measurement of a plasma current in a thermonuclear fusion reactor with a POTDR setup

    NASA Astrophysics Data System (ADS)

    Aerssens, M.; Gusarov, A.; Moreau, P.; Malard, P.; Massaut, V.; Mégret, P.; Wuilpart, M.

    2012-04-01

    Fibre optical current sensor (FOCS) is a promising alternative to inductive sensors for the measurement of the plasma current in future thermonuclear fusion reactors. Standard FOCS relies on the measurement of the state of polarisation (SOP) of light at the output of an optical bre surrounding a current. Because of the Faraday eect, magnetic eld induced by electrical current rotates the SOP of light travelling into the bre. According to the Ampere's theorem this rotation is proportional to the surrounded current. In future tokamaks like ITER and DEMO, the plasma current will be suciently high to generate a rotation of the SOP higher than 2 radians. These conditions may lead to uncertainties on the determination of the plasma current if no post processing is performed. In this paper we propose a solution with a Polarisation Optical Time Domain Re ectometer (POTDR) setup allowing both unambiguous plasma current measurement and also local magnetic eld measurements. This measurement is based on the assessment of the SOP rotation of the Rayleigh backscattered POTDR signal. Thanks to the presence of an input polarizer, SOP variations are converted into power uctuations that contain information about the distribution of the magnetic eld and therefore about the plasma current. Using the Jones formalism we have developed a model accounting for the modication of the SOP of light travelling into the optical bre and the evolution of the POTDR signal. In parallel experimental PODTR measurements have been performed on the Tore Supra tokamak situated at CEA Cadarache in France. A comparison between the models and the experimental results conrms the capability of the system to measure the plasma current and the local magnetic eld even if further data post processing are still required.

  3. Nuclear reactor control apparatus

    DOEpatents

    Sridhar, Bettadapur N.

    1983-10-25

    Nuclear reactor safety rod release apparatus comprises a ring which carries detents normally positioned in an annular recess in outer side of the rod, the ring being held against the lower end of a drive shaft by magnetic force exerted by a solenoid carried by the drive shaft. When the solenoid is de-energized, the detent-carrying ring drops until the detents contact a cam surface associated with the lower end of the drive shaft, at which point the detents are cammed out of the recess in the safety rod to release the rod from the drive shaft. In preferred embodiments of the invention, an additional latch is provided to release a lower portion of a safety rod under conditions that may interfere with movement of the entire rod.

  4. Laser Fusion - A New Thermonuclear Concept

    ERIC Educational Resources Information Center

    Cooper, Ralph S.

    1975-01-01

    Describes thermonuclear processes induced by interaction of a laser beam with the surface of a fuel pellet. An expanding plasma is formed which results in compression of the element. Laser and reactor technology are discussed. Pictures and diagrams are included. (GH)

  5. Nucleosynthesis in Thermonuclear Supernovae

    SciTech Connect

    Claudia, Travaglio; Hix, William Raphael

    2013-01-01

    We review our understanding of the nucleosynthesis that occurs in thermonuclear supernovae and their contribution to Galactic Chemical evolution. We discuss the prospects to improve the modeling of the nucleosynthesis within simulations of these events.

  6. CONTROL SYSTEM FOR NEUTRONIC REACTORS

    DOEpatents

    Crever, F.E.

    1962-05-01

    BS>A slow-acting shim rod for control of major variations in reactor neutron flux and a fast-acting control rod to correct minor flux variations are employed to provide a sensitive, accurate control system. The fast-acting rod is responsive to an error signal which is produced by changes in the neutron flux from a predetermined optimum level. When the fast rod is thus actuated in a given direction, means is provided to actuate the slow-moving rod in that direction to return the fast rod to a position near the midpoint of its control range. (AEC)

  7. Reactivity control assembly for nuclear reactor

    DOEpatents

    Bollinger, Lawrence R.

    1984-01-01

    Reactivity control assembly for nuclear reactor comprises supports stacked above reactor core for holding control rods. Couplers associated with the supports and a vertically movable drive shaft have lugs at their lower ends for engagement with the supports.

  8. Fast-acting nuclear reactor control device

    DOEpatents

    Kotlyar, Oleg M.; West, Phillip B.

    1993-01-01

    A fast-acting nuclear reactor control device for moving and positioning a fety control rod to desired positions within the core of the reactor between a run position in which the safety control rod is outside the reactor core, and a shutdown position in which the rod is fully inserted in the reactor core. The device employs a hydraulic pump/motor, an electric gear motor, and solenoid valve to drive the safety control rod into the reactor core through the entire stroke of the safety control rod. An overrunning clutch allows the safety control rod to freely travel toward a safe position in the event of a partial drive system failure.

  9. Control rod drive for reactor shutdown

    DOEpatents

    McKeehan, Ernest R.; Shawver, Bruce M.; Schiro, Donald J.; Taft, William E.

    1976-01-20

    A means for rapidly shutting down or scramming a nuclear reactor, such as a liquid metal-cooled fast breeder reactor, and serves as a backup to the primary shutdown system. The control rod drive consists basically of an in-core assembly, a drive shaft and seal assembly, and a control drive mechanism. The control rod is driven into the core region of the reactor by gravity and hydraulic pressure forces supplied by the reactor coolant, thus assuring that common mode failures will not interfere with or prohibit scramming the reactor when necessary.

  10. PID Control Effectiveness for Surface Reactor Concepts

    SciTech Connect

    Dixon, David D.; Marsh, Christopher L.; Poston, David I.

    2007-01-30

    Control of space and surface fission reactors should be kept as simple as possible, because of the need for high reliability and the difficulty to diagnose and adapt to control system failures. Fortunately, compact, fast-spectrum, externally controlled reactors are very simple in operation. In fact, for some applications it may be possible to design low-power surface reactors without the need for any reactor control after startup; however, a simple proportional, integral, derivative (PID) controller can allow a higher performance concept and add more flexibility to system operation. This paper investigates the effectiveness of a PID control scheme for several anticipated transients that a surface reactor might experience. To perform these analyses, the surface reactor transient code FRINK was modified to simulate control drum movements based on bulk coolant temperature.

  11. BOILING SLURRY REACTOR AND METHOD FO CONTROL

    DOEpatents

    Petrick, M.; Marchaterre, J.F.

    1963-05-01

    The control of a boiling slurry nuclear reactor is described. The reactor consists of a vertical tube having an enlarged portion, a steam drum at the top of the vertical tube, and at least one downcomer connecting the steam drum and the bottom of the vertical tube, the reactor being filled with a slurry of fissionabie material in water of such concentration that the enlarged portion of the vertical tube contains a critical mass. The slurry boils in the vertical tube and circulates upwardly therein and downwardly in the downcomer. To control the reactor by controlling the circulation of the slurry, a gas is introduced into the downcomer. (AEC)

  12. Topaz-II reactor control unit development

    SciTech Connect

    Wyant, F.J.; Jensen, D.; Logothetis, J.

    1994-12-31

    The development for a new digital reactor control unit for the Topaz-II reactor is described. The unit is expected to provide the means for automated control during a possible Topaz flight experiment. The breadboard design and development is discussed.

  13. Safety control circuit for a neutronic reactor

    DOEpatents

    Ellsworth, Howard C.

    2004-04-27

    A neutronic reactor comprising an active portion containing material fissionable by neutrons of thermal energy, means to control a neutronic chain reaction within the reactor comprising a safety device and a regulating device, a safety device including means defining a vertical channel extending into the reactor from an aperture in the upper surface of the reactor, a rod containing neutron-absorbing materials slidably disposed within the channel, means for maintaining the safety rod in a withdrawn position relative to the active portion of the reactor including means for releasing said rod on actuation thereof, a hopper mounted above the active portion of the reactor having a door disposed at the bottom of the hopper opening into the vertical channel, a plurality of bodies of neutron-absorbing materials disposed within the hopper, and means responsive to the failure of the safety rod on actuation thereof to enter the active portion of the reactor for opening the door in the hopper.

  14. NEUTRON DENSITY CONTROL IN A NEUTRONIC REACTOR

    DOEpatents

    Young, G.J.

    1959-06-30

    The method and means for controlling the neutron density in a nuclear reactor is described. It describes the method and means for flattening the neutron density distribution curve across the reactor by spacing the absorbing control members to varying depths in the central region closer to the center than to the periphery of the active portion of the reactor to provide a smaller neutron reproduction ratio in the region wherein the members are inserted, than in the remainder of the reactor thereby increasing the over-all potential power output.

  15. Autonomous Control of Space Nuclear Reactors

    NASA Technical Reports Server (NTRS)

    Merk, John

    2013-01-01

    Nuclear reactors to support future robotic and manned missions impose new and innovative technological requirements for their control and protection instrumentation. Long-duration surface missions necessitate reliable autonomous operation, and manned missions impose added requirements for failsafe reactor protection. There is a need for an advanced instrumentation and control system for space-nuclear reactors that addresses both aspects of autonomous operation and safety. The Reactor Instrumentation and Control System (RICS) consists of two functionally independent systems: the Reactor Protection System (RPS) and the Supervision and Control System (SCS). Through these two systems, the RICS both supervises and controls a nuclear reactor during normal operational states, as well as monitors the operation of the reactor and, upon sensing a system anomaly, automatically takes the appropriate actions to prevent an unsafe or potentially unsafe condition from occurring. The RPS encompasses all electrical and mechanical devices and circuitry, from sensors to actuation device output terminals. The SCS contains a comprehensive data acquisition system to measure continuously different groups of variables consisting of primary measurement elements, transmitters, or conditioning modules. These reactor control variables can be categorized into two groups: those directly related to the behavior of the core (known as nuclear variables) and those related to secondary systems (known as process variables). Reliable closed-loop reactor control is achieved by processing the acquired variables and actuating the appropriate device drivers to maintain the reactor in a safe operating state. The SCS must prevent a deviation from the reactor nominal conditions by managing limitation functions in order to avoid RPS actions. The RICS has four identical redundancies that comply with physical separation, electrical isolation, and functional independence. This architecture complies with the

  16. Nuclear electric propulsion reactor control systems status

    NASA Technical Reports Server (NTRS)

    Ferg, D. A.

    1973-01-01

    The thermionic reactor control system design studies conducted over the past several years for a nuclear electric propulsion system are described and summarized. The relevant reactor control system studies are discussed in qualitative terms, pointing out the significant advantages and disadvantages including the impact that the various control systems would have on the nuclear electric propulsion system design. A recommendation for the reference control system is made, and a program for future work leading to an engineering model is described.

  17. TREAT Reactor Control and Protection System

    SciTech Connect

    Lipinski, W.C.; Brookshier, W.K.; Burrows, D.R.; Lenkszus, F.R.; McDowell, W.P.

    1985-01-01

    The main control algorithm of the Transient Reactor Test Facility (TREAT) Automatic Reactor Control System (ARCS) resides in Read Only Memory (ROM) and only experiment specific parameters are input via keyboard entry. Prior to executing an experiment, the software and hardware of the control computer is tested by a closed loop real-time simulation. Two computers with parallel processing are used for the reactor simulation and another computer is used for simulation of the control rod system. A monitor computer, used as a redundant diverse reactor protection channel, uses more conservative setpoints and reduces challenges to the Reactor Trip System (RTS). The RTS consists of triplicated hardwired channels with one out of three logic. The RTS is automatically tested by a digital Dedicated Microprocessor Tester (DMT) prior to the execution of an experiment. 6 refs., 5 figs., 1 tab.

  18. Reactivity control assembly for nuclear reactor. [LMFBR

    DOEpatents

    Bollinger, L.R.

    1982-03-17

    This invention, which resulted from a contact with the United States Department of Energy, relates to a control mechanism for a nuclear reactor and, more particularly, to an assembly for selectively shifting different numbers of reactivity modifying rods into and out of the core of a nuclear reactor. It has been proposed heretofore to control the reactivity of a breeder reactor by varying the depth of insertion of control rods (e.g., rods containing a fertile material such as ThO/sub 2/) in the core of the reactor, thereby varying the amount of neutron-thermalizing coolant and the amount of neutron-capturing material in the core. This invention relates to a mechanism which can advantageously be used in this type of reactor control system.

  19. Fission control system for nuclear reactor

    DOEpatents

    Conley, G.H.; Estes, G.P.

    Control system for nuclear reactor comprises a first set of reactivity modifying rods fixed in a reactor core with their upper ends stepped in height across the core, and a second set of reactivity modifying rods movable vertically within the reactor core and having their lower ends stepped to correspond with the stepped arrangement of the first set of rods, pairs of the rods of the first and second sets being in coaxial alignment.

  20. DENSITY CONTROL IN A REACTOR

    DOEpatents

    Marshall, J. Jr.

    1961-10-24

    A reactor is described in which natural-uranium bodies are located in parallel channels which extend through the graphite mass in a regular lattice. The graphite mass has additional channels that are out of the lattice and contain no uranium. These additional channels decrease in number per unit volume of graphite from the center of the reactor to the exterior and have the effect of reducing the density of the graphite more at the center than at the exterior, thereby spreading neutron activity throughout the reactor. (AEC)

  1. NEUTRONIC REACTOR CONTROL ROD DRIVE APPARATUS

    DOEpatents

    Oakes, L.C.; Walker, C.S.

    1959-12-15

    ABS>A suspension mechanism between a vertically movable nuclear reactor control rod and a rod extension, which also provides information for the operator or an automatic control signal, is described. A spring connects the rod extension to a drive shift. The extension of the spring indicates whether (1) the rod is at rest on the reactor, (2) the rod and extension are suspended, or (3) the extension alone is suspended, the spring controlling a 3-position electrical switch.

  2. Control system for a small fission reactor

    DOEpatents

    Burelbach, James P.; Kann, William J.; Saiveau, James G.

    1986-01-01

    A system for controlling the reactivity of a small fission reactor includes an elongated, flexible hollow tube in the general form of a helical coiled spring axially positioned around and outside of the reactor vessel in an annular space between the reactor vessel and a surrounding cylindrical-shaped neutron reflector. A neutron absorbing material is provided within the hollow tube with the rate of the reaction controlled by the extension and compression of the hollow tube, e.g., extension of the tube increases reactivity while its compression reduces reactivity, in varying the amount of neutron absorbing material disposed between the reactor vessel and the neutron reflector. Conventional mechanical displacement means may be employed to control the coil density of the hollow tube as desired. In another embodiment, a plurality of flexible hollow tubes each containing a neutron absorber are positioned adjacent to one another in spaced relation around the periphery of the reactor vessel and inside the outer neutron reflector with reactivity controlled by the extension and compression of all or some of the coiled hollow tubes. Yet another embodiment of the invention envisions the neutron reflector in the form of an expandable coil spring positioned in an annular space between the reactor vessel and an outer neutron absorbing structure for controlling the neutron flux reflected back into the reactor vessel.

  3. Control system for a small fission reactor

    DOEpatents

    Burelbach, J.P.; Kann, W.J.; Saiveau, J.G.

    1985-02-08

    A system for controlling the reactivity of a small fission reactor includes an elongated, flexible hollow tube in the general form of a helical coiled spring axially positioned around and outside of the reactor vessel in an annular space between the reactor vessel and a surrounding cylindrical-shaped neutron reflector. A neutron absorbing material is provided within the hollow tube with the rate of the reaction controlled by the extension and compression of the hollow tube, e.g., extension of the tube increases reactivity while its compression reduces reactivity, in varying the amount of neutron absorbing material disposed between the reactor vessel and the neutron reflector. Conventional mechanical displacement means may be employed to control the coil density of the hollow tube as desired.

  4. METHOD AND APPARATUS FOR CONTROLLING DIRECT-CYCLE NEUTRONIC REACTORS

    DOEpatents

    Reed, G.A.

    1961-01-10

    A control arrangement is offered for a boiling-water reactor. Boric acid is maintained in the water in the reactor and the amount in the reactor is controlled by continuously removing a portion of the water from the reactor, concentrating the boric acid by evaporating the water therefrom, returning a controlled amount of the acid to the reactor, and simultaneously controlling the water level by varying the rate of spent steam return to the reactor.

  5. APPARATUS FOR CONTROLLING NEUTRONIC REACTORS

    DOEpatents

    Dietrich, J.R.; Harrer, J.M.

    1958-09-16

    A device is described for rapidly cortrolling the reactivity of an active portion of a reactor. The inveniion consists of coaxially disposed members each having circumferenital sections of material having dlfferent neutron absorbing characteristics and means fur moving the members rotatably and translatably relative to each other within the active portion to vary the neutron flux therein. The angular and translational movements of any member change the neutron flux shadowing effect of that member upon the other member.

  6. Control Rod Malfunction at the NRAD Reactor

    SciTech Connect

    Thomas L. Maddock

    2010-05-01

    The neutron Radiography Reactor (NRAD) is a training, research, and isotope (TRIGA) reactor located at the INL. The reactor is normally shut down by the insertion of three control rods that drop into the core when power is removed from electromagnets. During a routine shutdown, indicator lights on the console showed that one of the control rods was not inserted. It was initially thought that the indicator lights were in error because of a limit switch that was out of adjustment. Through further testing, it was determined that the control rod did not drop when the scram switch was initially pressed. The control rod anomaly led to a six month shutdown of the reactor and an in depth investigation of the reactor protective system. The investigation looked into: scram switch operation, console modifications, and control rod drive mechanisms. A number of latent issues were discovered and corrected during the investigation. The cause of the control rod malfunction was found to be a buildup of corrosion in the control rod drive mechanism. The investigation resulted in modifications to equipment, changes to both operation and maintenance procedures, and additional training. No reoccurrences of the problem have been observed since corrective actions were implemented.

  7. Reactor control rod timing system. [LMFBR

    DOEpatents

    Wu, P.T.K.

    1980-03-18

    A fluid driven jet-edge whistle timing system is described for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

  8. Autonomous Control of Space Reactor Systems

    SciTech Connect

    Belle R. Upadhyaya; K. Zhao; S.R.P. Perillo; Xiaojia Xu; M.G. Na

    2007-11-30

    Autonomous and semi-autonomous control is a key element of space reactor design in order to meet the mission requirements of safety, reliability, survivability, and life expectancy. Interrestrial nuclear power plants, human operators are avilable to perform intelligent control functions that are necessary for both normal and abnormal operational conditions.

  9. CONTROL MEANS FOR A NUCLEAR REACTOR

    DOEpatents

    Teitel, R.J.

    1961-09-01

    A control means is described for a reactor which employs a liquid fuel consisting of a fissile isotope in a liquid bismuth solvent. The liquid fuel is contained in a plurality of tubular vessels. Control is effected by inserting plungers in the vessels to displace the liquid fuel and provide a critical or non- critical fuel configuration as desired.

  10. Damper mechanism for nuclear reactor control elements

    DOEpatents

    Taft, William Elwood

    1976-01-01

    A damper mechanism which provides a nuclear reactor control element decelerating function at the end of the scram stroke. The total damping function is produced by the combination of two assemblies, which operate in sequence. First, a tapered dashram assembly decelerates the control element to a lower velocity, after which a spring hydraulic damper assembly takes over to complete the final damping.

  11. Control system studies for thermionic reactors

    NASA Technical Reports Server (NTRS)

    Hermsen, R. J.; Gronroos, H. G.

    1978-01-01

    In core thermionic reactor concepts are of interest for space missions that require electrical power in the range of a few tens of kilowatts up to several megawatts. The physical principle involved--thermionic direct conversion of heat to electricity at net efficiencies up to 15 percent--offers potential advantages when compared to other nuclear powerplant concepts. However, the integration of the thermionic diode electrode structure with high-temperature nuclear fuel materials presents new design problems and new reactor physical constraints. Among the topics that must be investigated are those associated with the control system. The results of analytical and simulation studies of thermionic reactor control performed at the Jet Propulsion Laboratory are discussed.

  12. Magnetic switch for reactor control rod. [LMFBR

    DOEpatents

    Germer, J.H.

    1982-09-30

    A magnetic reed switch assembly is described for activating an electromagnetic grapple utilized to hold a control rod in position above a reactor core. In normal operation the magnetic field of a permanent magnet is short-circuited by a magnetic shunt, diverting the magnetic field away from the reed switch. The magnetic shunt is made of a material having a Curie-point at the desired release temperature. Above that temperature the material loses its ferromagnetic properties, and the magnetic path is diverted to the reed switch which closes and short-circuits the control circuit for the control rod electro-magnetic grapple which allows the control rod to drop into the reactor core for controlling the reactivity of the core.

  13. Magnetic switch for reactor control rod

    DOEpatents

    Germer, John H.

    1986-01-01

    A magnetic reed switch assembly for activating an electromagnetic grapple utilized to hold a control rod in position above a reactor core. In normal operation the magnetic field of a permanent magnet is short-circuited by a magnetic shunt, diverting the magnetic field away from the reed switch. The magnetic shunt is made of a material having a Curie-point at the desired release temperature. Above that temperature the material loses its ferromagnetic properties, and the magnetic path is diverted to the reed switch which closes and short-circuits the control circuit for the control rod electromagnetic grapple which allows the control rod to drop into the reactor core for controlling the reactivity of the core.

  14. Nuclear reactor control room construction

    DOEpatents

    Lamuro, Robert C.; Orr, Richard

    1993-01-01

    A control room 10 for a nuclear plant is disclosed. In the control room, objects 12, 20, 22, 26, 30 are no less than four inches from walls 10.2. A ceiling 32 contains cooling fins 35 that extend downwards toward the floor from metal plates 34. A concrete slab 33 is poured over the plates. Studs 36 are welded to the plates and are encased in the concrete.

  15. Nuclear reactor control room construction

    DOEpatents

    Lamuro, R.C.; Orr, R.

    1993-11-16

    A control room for a nuclear plant is disclosed. In the control room, objects labelled 12, 20, 22, 26, 30 in the drawing are no less than four inches from walls labelled 10.2. A ceiling contains cooling fins that extend downwards toward the floor from metal plates. A concrete slab is poured over the plates. Studs are welded to the plates and are encased in the concrete. 6 figures.

  16. METHOD AND APPARATUS FOR REACTOR SAFETY CONTROL

    DOEpatents

    Huston, N.E.

    1961-06-01

    A self-contained nuclear reactor fuse controlled device tron absorbing material, normally in a compact form but which can be expanded into an extended form presenting a large surface for neutron absorption when triggered by an increase in neutron flux, is described.

  17. Nuclear reactor shutdown control rod assembly

    DOEpatents

    Bilibin, Konstantin

    1988-01-01

    A temperature responsive, self-actuated nuclear reactor shutdown control rod assembly 10. The upper end 18 of a lower drive line 17 fits within the lower end of an upper drive line 12. The lower end (not shown) of the lower drive line 17 is connected to a neutron absorber. During normal temperature conditions the lower drive line 17 is supported by detent means 22,26. When an overtemperature condition occurs thermal actuation means 34 urges ring 26 upwardly sufficiently to allow balls 22 to move radially outwardly thereby allowing lower drive line 17 to move downwardly toward the core of the nuclear reactor resulting in automatic reduction of the reactor powder.

  18. Power flow control using distributed saturable reactors

    DOEpatents

    Dimitrovski, Aleksandar D.

    2016-02-13

    A magnetic amplifier includes a saturable core having a plurality of legs. Control windings wound around separate legs are spaced apart from each other and connected in series in an anti-symmetric relation. The control windings are configured in such a way that a biasing magnetic flux arising from a control current flowing through one of the plurality of control windings is substantially equal to the biasing magnetic flux flowing into a second of the plurality of control windings. The flow of the control current through each of the plurality of control windings changes the reactance of the saturable core reactor by driving those portions of the saturable core that convey the biasing magnetic flux in the saturable core into saturation. The phasing of the control winding limits a voltage induced in the plurality of control windings caused by a magnetic flux passing around a portion of the saturable core.

  19. MEANS FOR CONTROLLING A NUCLEAR REACTOR

    DOEpatents

    Wilson, V.C.; Overbeck, W.P.; Slotin, L.; Froman, D.K.

    1957-12-17

    This patent relates to nuclear reactors of the type using a solid neutron absorbing material as a means for controlling the reproduction ratio of the system and thereby the power output. Elongated rods of neutron absorbing material, such as boron steel for example, are adapted to be inserted and removed from the core of tae reactor by electronic motors and suitable drive means. The motors and drive means are controlled by means responsive to the neutron density, such as ionization chambers. The control system is designed to be responsive also to the rate of change in neutron density to automatically maintain the total power output at a substantially constant predetermined value. A safety rod means responsive to neutron density is also provided for keeping the power output below a predetermined maximum value at all times.

  20. Thermomagnetic burn control for magnetic fusion reactor

    DOEpatents

    Rawls, John M.; Peuron, Unto A.

    1982-01-01

    Apparatus is provided for controlling the plasma energy production rate of a magnetic-confinement fusion reactor, by controlling the magnetic field ripple. The apparatus includes a group of shield sectors (30a, 30b, etc.) formed of ferromagnetic material which has a temperature-dependent saturation magnetization, with each shield lying between the plasma (12) and a toroidal field coil (18). A mechanism (60) for controlling the temperature of the magnetic shields, as by controlling the flow of cooling water therethrough, thereby controls the saturation magnetization of the shields and therefore the amount of ripple in the magnetic field that confines the plasma, to thereby control the amount of heat loss from the plasma. This heat loss in turn determines the plasma state and thus the rate of energy production.

  1. Thermomagnetic burn control for magnetic fusion reactor

    DOEpatents

    Rawls, J.M.; Peuron, A.U.

    1980-07-01

    Apparatus is provided for controlling the plasma energy production rate of a magnetic-confinement fusion reactor, by controlling the magnetic field ripple. The apparatus includes a group of shield sectors formed of ferromagnetic material which has a temperature-dependent saturation magnetization, with each shield lying between the plasma and a toroidal field coil. A mechanism for controlling the temperature of the magnetic shields, as by controlling the flow of cooling water therethrough, thereby controls the saturation magnetization of the shields and therefore the amount of ripple in the magnetic field that confines the plasma, to thereby control the amount of heat loss from the plasma. This heat loss in turn determines the plasma state and thus the rate of energy production.

  2. SPRING DRIVEN ACTUATING MECHANISM FOR NUCLEAR REACTOR CONTROL

    DOEpatents

    Bevilacqua, F.; Uecker, D.F.; Groh, E.F.

    1962-01-23

    l962. rod in a nuclear reactor to shut it down. The control rod or an extension thereof is wound on a drum as it is withdrawn from the reactor. When an emergency occurs requiring the reactor to be shut down, the drum is released so as to be free to rotate, and the tendency of the control rod or its extension coiled on the drum to straighten itself is used for quickly returning the control rod to the reactor. (AEC)

  3. HIGH STRENGTH CONTROL RODS FOR NEUTRONIC REACTORS

    DOEpatents

    Lustman, B.; Losco, E.F.; Cohen, I.

    1961-07-11

    Nuclear reactor control rods comprised of highly compressed and sintered finely divided metal alloy panticles and fine metal oxide panticles substantially uniformly distributed theretbrough are described. The metal alloy consists essentially of silver, indium, cadmium, tin, and aluminum, the amount of each being present in centain percentages by weight. The oxide particles are metal oxides of the metal alloy composition, the amount of oxygen being present in certain percentages by weight and all the oxygen present being substantially in the form of metal oxide. This control rod is characterized by its high strength and resistance to creep at elevated temperatures.

  4. Variable flow control for a nuclear reactor control rod

    DOEpatents

    Carleton, Richard D.; Bhattacharyya, Ajay

    1978-01-01

    A variable flow control for a control rod assembly of a nuclear reactor that depends on turbulent friction though an annulus. The annulus is formed by a piston attached to the control rod drive shaft and a housing or sleeve fitted to the enclosure housing the control rod. As the nuclear fuel is burned up and the need exists for increased reactivity, the control rods are withdrawn, which increases the length of the annulus and decreases the rate of coolant flow through the control rod assembly.

  5. Control rod for a nuclear reactor

    DOEpatents

    Roman, Walter G.; Sutton, Jr., Harry G.

    1979-01-01

    A control rod assembly for a nuclear reactor is disclosed having a remotely disengageable coupling between the control rod and the control rod drive shaft. The coupling is actuated by first lowering then raising the drive shaft. The described motion causes axial repositioning of a pin in a grooved rotatable cylinder, each being attached to different parts of the drive shaft which are axially movable relative to each other. In one embodiment, the relative axial motion of the parts of the drive shaft is used either to couple or to uncouple the connection by forcing resilient members attached to the drive shaft into or out of shouldered engagement, respectively, with an indentation formed in the control rod.

  6. Programmable AC power supply for simulating power transient expected in fusion reactor

    SciTech Connect

    Halimi, B.; Suh, K. Y.

    2012-07-01

    This paper focus on control engineering of the programmable AC power source which has capability to simulate power transient expected in fusion reactor. To generate the programmable power source, AC-AC power electronics converter is adopted to control the power of a set of heaters to represent the transient phenomena of heat exchangers or heat sources of a fusion reactor. The International Thermonuclear Experimental Reactor (ITER) plasma operation scenario is used as the basic reference for producing this transient power source. (authors)

  7. Thermonuclear supernovae: simulations of the deflagration stage and their implications.

    PubMed

    Gamezo, Vadim N; Khokhlov, Alexei M; Oran, Elaine S; Chtchelkanova, Almadena Y; Rosenberg, Robert O

    2003-01-01

    Large-scale, three-dimensional numerical simulations of the deflagration stage of a thermonuclear supernova explosion show the formation and evolution of a highly convoluted turbulent flame in the gravitational field of an expanding carbon-oxygen white dwarf. The flame dynamics are dominated by the gravity-induced Rayleigh-Taylor instability that controls the burning rate. The thermonuclear deflagration releases enough energy to produce a healthy explosion. The turbulent flame, however, leaves large amounts of unburned and partially burned material near the star center, whereas observations that imply these materials are present only in outer layers. This disagreement could be resolved if the deflagration triggers a detonation. PMID:12446871

  8. Thermonuclear supernovae: simulations of the deflagration stage and their implications.

    PubMed

    Gamezo, Vadim N; Khokhlov, Alexei M; Oran, Elaine S; Chtchelkanova, Almadena Y; Rosenberg, Robert O

    2003-01-01

    Large-scale, three-dimensional numerical simulations of the deflagration stage of a thermonuclear supernova explosion show the formation and evolution of a highly convoluted turbulent flame in the gravitational field of an expanding carbon-oxygen white dwarf. The flame dynamics are dominated by the gravity-induced Rayleigh-Taylor instability that controls the burning rate. The thermonuclear deflagration releases enough energy to produce a healthy explosion. The turbulent flame, however, leaves large amounts of unburned and partially burned material near the star center, whereas observations that imply these materials are present only in outer layers. This disagreement could be resolved if the deflagration triggers a detonation.

  9. Adaptive robust control of the EBR-II reactor

    SciTech Connect

    Power, M.A.; Edwards, R.M.

    1996-05-01

    Simulation results are presented for an adaptive H{sub {infinity}} controller, a fixed H{sub {infinity}} controller, and a classical controller. The controllers are applied to a simulation of the Experimental Breeder Reactor II primary system. The controllers are tested for the best robustness and performance by step-changing the demanded reactor power and by varying the combined uncertainty in initial reactor power and control rod worth. The adaptive H{sub {infinity}} controller shows the fastest settling time, fastest rise time and smallest peak overshoot when compared to the fixed H{sub {infinity}} and classical controllers. This makes for a superior and more robust controller.

  10. Active disturbance rejection controller for chemical reactor

    SciTech Connect

    Both, Roxana; Dulf, Eva H.; Muresan, Cristina I.

    2015-03-10

    In the petrochemical industry, the synthesis of 2 ethyl-hexanol-oxo-alcohols (plasticizers alcohol) is of high importance, being achieved through hydrogenation of 2 ethyl-hexenal inside catalytic trickle bed three-phase reactors. For this type of processes the use of advanced control strategies is suitable due to their nonlinear behavior and extreme sensitivity to load changes and other disturbances. Due to the complexity of the mathematical model an approach was to use a simple linear model of the process in combination with an advanced control algorithm which takes into account the model uncertainties, the disturbances and command signal limitations like robust control. However the resulting controller is complex, involving cost effective hardware. This paper proposes a simple integer-order control scheme using a linear model of the process, based on active disturbance rejection method. By treating the model dynamics as a common disturbance and actively rejecting it, active disturbance rejection control (ADRC) can achieve the desired response. Simulation results are provided to demonstrate the effectiveness of the proposed method.

  11. Self-teaching neural network learns difficult reactor control problem

    SciTech Connect

    Jouse, W.C.

    1989-01-01

    A self-teaching neural network used as an adaptive controller quickly learns to control an unstable reactor configuration. The network models the behavior of a human operator. It is trained by allowing it to operate the reactivity control impulsively. It is punished whenever either the power or fuel temperature stray outside technical limits. Using a simple paradigm, the network constructs an internal representation of the punishment and of the reactor system. The reactor is constrained to small power orbits.

  12. Autonomous Control and Diagnostics of Space Reactor Systems

    SciTech Connect

    Upadhyaya, B.R.; Xu, X.; Perillo, S.R.P.; Na, M.G.

    2006-07-01

    This paper describes three key features of the development of an autonomous control strategy for space reactor systems. These include the development of a reactor simulation model for transient analysis, development of model-predictive control as part of the autonomous control strategy, and a fault detection and isolation module. The latter is interfaced with the control supervisor as part of a hierarchical control system. The approach has been applied to the nodal model of the SP-100 reactor with a thermo-electric generator. The results of application demonstrate the effectiveness of the control approach and its ability to reconfigure the control mode under fault conditions. (authors)

  13. Thermonuclear ignition criterion in ICF

    NASA Astrophysics Data System (ADS)

    Cheng, Baolian

    2010-11-01

    The Lawson criterion, which determines the onset of thermonuclear ignition in inertial confinement fusion (ICF), is re-derived in terms of physical measurable quantities: the hot spot ion temperature T and the areal density (ρR) of the deuterium-tritium (DT) gas. From this criterion, an ignition curve is generated in the ρR -T plane. In addition, a minimal required implosion energy for laser-drive and a minimal DT gas mass for a sustainable ignition with respect to the condition are derived.

  14. Theoretical determination of the strength characteristics of multilayer materials intended for nuclear and thermonuclear engineering

    NASA Astrophysics Data System (ADS)

    Vitkovskii, I. V.; Leshukov, A. Yu.; Romashin, S. N.; Shorkin, V. S.

    2015-12-01

    A method is developed to estimate the integrity of multilayer structures. This method is based on the version of the theory of adhesion and cohesion interactions of structure elements that only takes into account their thermomechanical properties. The structures to be studied are the material of the multilayer wall of the liquid-metal thermonuclear reactor blanket and a heat-resistant magnet wire with a bimetallic conductor, which is the base of the windings of the magnetohydrodynamic machines and electric motors intended for operation at high temperatures under ionizing radiation in, e.g., the machines and facilities in nuclear and thermonuclear reactors.

  15. REACTOR

    DOEpatents

    Szilard, L.

    1963-09-10

    A breeder reactor is described, including a mass of fissionable material that is less than critical with respect to unmoderated neutrons and greater than critical with respect to neutrons of average energies substantially greater than thermal, a coolant selected from sodium or sodium--potassium alloys, a control liquid selected from lead or lead--bismuth alloys, and means for varying the quantity of control liquid in the reactor. (AEC)

  16. PBF Reactor Building (PER620). Camera looks into reactor vessel. Control ...

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

    PBF Reactor Building (PER-620). Camera looks into reactor vessel. Control rods are positioned at outer perimeter; transient rods, at inner perimeter. Photographer: Larry Page. Date: November 2, 1972. INEEL negative no. 72-5266 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

  17. Tidally-Induced Thermonuclear Supernovae

    SciTech Connect

    Rosswog, S.; Ramirez-Ruiz, E.; Hix, William Raphael

    2009-01-01

    We discuss the results of 3D simulations of tidal disruptions of white dwarfs by moderate-mass black holes as they may exist in the cores of globular clusters or dwarf galaxies. Our simulations follow self-consistently the hydrodynamic and nuclear evolution from the initial parabolic orbit over the disruption to the build-up of an accretion disk around the black hole. For strong enough encounters (pericentre distances smaller than about 1/3 of the tidal radius) the tidal compression is reversed by a shock and finally results in a thermonuclear explosion. These explosions are not restricted to progenitor masses close to the Chandrasekhar limit, we find exploding examples throughout the whole white dwarf mass range. There is, however, a restriction on the masses of the involved black holes: black holes more massive than 2x105M{circle_dot} swallow a typical 0.6M{circle_dot} white dwarf before their tidal forces can overwhelm the star's selfgravity. Therefore, this mechanism is characteristic for black holes of moderate masses. The material that remains bound to the black hole settles into an accretion disk and produces an Xray flare close to the Eddington limit of L{sub Edd} {approx} 10{sup 41}erg/s (Mbh/1000M{circle_dot}), typically lasting for a few months. The combination of a peculiar thermonuclear supernova together with an X-ray flare thus whistle-blows the existence of such moderate-mass black holes. The next generation of wide field space-based instruments should be able to detect such events.

  18. REACTOR

    DOEpatents

    Christy, R.F.

    1961-07-25

    A means is described for co-relating the essential physical requirements of a fission chain reaction in order that practical, compact, and easily controllable reactors can be built. These objects are obtained by employing a composition of fissionsble isotope and moderator in fluid form in which the amount of fissionsble isotcpe present governs the reaction. The size of the reactor is no longer a critical factor, the new criterion being the concentration of the fissionable isotope.

  19. Control of autothermal reforming reactor of diesel fuel

    NASA Astrophysics Data System (ADS)

    Dolanc, Gregor; Pregelj, Boštjan; Petrovčič, Janko; Pasel, Joachim; Kolb, Gunther

    2016-05-01

    In this paper a control system for autothermal reforming reactor for diesel fuel is presented. Autothermal reforming reactors and the pertaining purification reactors are used to convert diesel fuel into hydrogen-rich reformate gas, which is then converted into electricity by the fuel cell. The purpose of the presented control system is to control the hydrogen production rate and the temperature of the autothermal reforming reactor. The system is designed in such a way that the two control loops do not interact, which is required for stable operation of the fuel cell. The presented control system is a part of the complete control system of the diesel fuel cell auxiliary power unit (APU).

  20. METHOD AND APPARATUS FOR CONTROL OF A NUCLEAR REACTOR

    DOEpatents

    Cawley, W.E.

    1962-12-11

    A method and apparatus are described for controlling an overmoderated nuclear reactor containing columns of fuel elements aligned in a plurality of coolant tubes in a stream of coolant water. The invention includes means for adjusting the distance between halves of the fuel element column to vary the relative proportion of fuel and moderator at the center of the reactor. (AEC)

  1. REACTOR

    DOEpatents

    Roman, W.G.

    1961-06-27

    A pressurized water reactor in which automatic control is achieved by varying the average density of the liquid moderator-cooiant is patented. Density is controlled by the temperature and power level of the reactor ftself. This control can be effected by the use of either plate, pellet, or tubular fuel elements. The fuel elements are disposed between upper and lower coolant plenum chambers and are designed to permit unrestricted coolant flow. The control chamber has an inlet opening communicating with the lower coolant plenum chamber and a restricted vapor vent communicating with the upper coolant plenum chamber. Thus, a variation in temperature of the fuel elements will cause a variation in the average moderator density in the chamber which directly affects the power level of the reactor.

  2. Dual annular rotating "windowed" nuclear reflector reactor control system

    DOEpatents

    Jacox, Michael G.; Drexler, Robert L.; Hunt, Robert N. M.; Lake, James A.

    1994-01-01

    A nuclear reactor control system is provided in a nuclear reactor having a core operating in the fast neutron energy spectrum where criticality control is achieved by neutron leakage. The control system includes dual annular, rotatable reflector rings. There are two reflector rings: an inner reflector ring and an outer reflector ring. The reflectors are concentrically assembled, surround the reactor core, and each reflector ring includes a plurality of openings. The openings in each ring are capable of being aligned or non-aligned with each other. Independent driving means for each of the annular reflector rings is provided so that reactor criticality can be initiated and controlled by rotation of either reflector ring such that the extent of alignment of the openings in each ring controls the reflection of neutrons from the core.

  3. Use of liquid metals in nuclear and thermonuclear engineering, and in other innovative technologies

    NASA Astrophysics Data System (ADS)

    Rachkov, V. I.; Arnol'dov, M. N.; Efanov, A. D.; Kalyakin, S. G.; Kozlov, F. A.; Loginov, N. I.; Orlov, Yu. I.; Sorokin, A. P.

    2014-05-01

    By now, a good deal of experience has been gained with using liquid metals as coolants in nuclear power installations; extensive knowledge has been gained about the physical, thermophysical, and physicochemical properties of these coolants; and the scientific principles and a set of methods and means for handling liquid metals as coolants for nuclear power installations have been elaborated. Prototype and commercialgrade sodium-cooled NPP power units have been developed, including the BOR-60, BN-350, and BN-600 power units (the Soviet Union); the Rapsodie, Phenix, and Superphenix power units (France), the EBR-II power unit (the United States); and the PFR power unit (the United Kingdom). In Russia, dedicated nuclear power installations have been constructed, including those with a lead-bismuth coolant for nuclear submarines and with sodium-potassium alloy for spacecraft (the Buk and Topol installations), which have no analogs around the world. Liquid metals (primarily lithium and its alloy with lead) hold promise for use in thermonuclear power engineering, where they can serve not only as a coolant, but also as tritium-producing medium. In this article, the physicochemical properties of liquid metal coolants, as well as practical experience gained from using them in nuclear and thermonuclear power engineering and in innovative technologies are considered, and the lines of further research works are formulated. New results obtained from investigations carried out on the Pb-Bi and Pb for the SVBR and BREST fast-neutron reactors (referred to henceforth as fast reactors) and for controlled accelerator systems are described.

  4. NGNP Reactor Coolant Chemistry Control Study

    SciTech Connect

    Brian Castle

    2010-11-01

    The main focus of this paper is to identify the most desirable ranges of impurity levels in the primary coolant to optimize component life in the primary circuit of the Next Generation Nuclear Plant (NGNP), which will either be a prismatic block or pebble bed reactor.

  5. Nuclear reactor flow control method and apparatus

    DOEpatents

    Church, John P.

    1993-01-01

    Method and apparatus for improving coolant flow in a nuclear reactor during accident as well as nominal conditions. The reactor has a plurality of fuel elements in sleeves and a plenum above the fuel and through which the sleeves penetrate. Holes are provided in the sleeve so that coolant from the plenum can enter the sleeve and cool the fuel. The number and size of the holes are varied from sleeve to sleeve with the number and size of holes being greater for sleeves toward the center of the core and less for sleeves toward the periphery of the core. Preferably the holes are all the same diameter and arranged in rows and columns, the rows starting from the bottom of every sleeve and fewer rows in peripheral sleeves and more rows in the central sleeves.

  6. 28. A typical main control panel in a 105 reactor ...

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

    28. A typical main control panel in a 105 reactor building, in this case 105-F in February 1945. A single operator sat at the controls to regulate the pile's rate of reaction and monitor it for safety. The galvanometer screens (the two horizontal bars just below the nine round gauges that showed the positions of the control rods) showed the pile's current power setting. With that information, the operator could set the control rod positions to increase, decrease, or maintain the power. D-8310 - B Reactor, Richland, Benton County, WA

  7. Instrumentation and control improvements at Experimental Breeder Reactor II

    SciTech Connect

    Christensen, L.J.; Planchon, H.P.

    1993-01-01

    The purpose of this paper is to describe instrumentation and control (I C) system improvements at Experimental Breeder Reactor 11 (EBR-11). The improvements are focused on three objectives; to keep the reactor and balance of plant (BOP) I C systems at a high level of reliability, to provide diagnostic systems that can provide accurate information needed for analysis of fuel performance, and to provide systems that will be prototypic of I C systems of the next generation of liquid metal reactor (LMR) plants.

  8. Instrumentation and control improvements at Experimental Breeder Reactor II

    SciTech Connect

    Christensen, L.J.; Planchon, H.P.

    1993-03-01

    The purpose of this paper is to describe instrumentation and control (I&C) system improvements at Experimental Breeder Reactor 11 (EBR-11). The improvements are focused on three objectives; to keep the reactor and balance of plant (BOP) I&C systems at a high level of reliability, to provide diagnostic systems that can provide accurate information needed for analysis of fuel performance, and to provide systems that will be prototypic of I&C systems of the next generation of liquid metal reactor (LMR) plants.

  9. Anticipatory control of xenon in a pressurized water reactor

    SciTech Connect

    Impink, A.J. Jr.

    1987-02-10

    A method is described for automatically dampening xenon-135 spatial transients in the core of a pressurized water reactor having control rods which regulate reactor power level, comprising the steps of: measuring the neutron flu in the reactor core at a plurality of axially spaced locations on a real-time, on-line basis; repetitively generating from the neutron flux measurements, on a point-by-point basis, signals representative of the current axial distribution of xenon-135, and signals representative of the current rate of change of the axial distribution of xenon-135; generating from the xenon-135 distribution signals and the rate of change of xenon distribution signals, control signals for reducing the xenon transients; and positioning the control rods as a function of the control signals to dampen the xenon-135 spatial transients.

  10. Reactivity Control Schemes for Fast Spectrum Space Nuclear Reactors

    SciTech Connect

    Craft, Aaron E.; King, Jeffrey C.

    2008-01-21

    Several different reactivity control schemes are considered for future space nuclear reactor power systems. Each of these control schemes uses a combination of boron carbide absorbers and/or beryllium oxide reflectors to achieve sufficient reactivity swing to keep the reactor subcritical during launch and to provide sufficient excess reactivity to operate the reactor over its expected 7-15 year lifetime. The size and shape of the control system directly impacts the size and mass of the space reactor's reflector and shadow shield, leading to a tradeoff between reactivity swing and total system mass. This paper presents a trade study of drum, shutter, and petal control schemes based on reactivity swing and mass effects for a representative fast-spectrum, gas-cooled reactor. For each control scheme, the dimensions and composition of the core are constant, and the reflector is sized to provide $5 of cold-clean excess reactivity with each configuration in its most reactive state. The advantages and disadvantages of each configuration are discussed, along with optimization techniques and novel geometric approaches for each scheme.

  11. On extended thermonuclear functions through pathway model

    NASA Astrophysics Data System (ADS)

    Kumar, Dilip

    when α → 1. The beauty of the result is that these different families of three different functional forms are covered through the pathway parameter α. In a physical set up if f (x) in (3) is the stable or limiting form, the Maxwell-Boltzmann approach to thermonuclear functions, then f (x) in (1) and (2) will contain a large variety of unstable or chaotic situations which will all tend to (3) in the limit. Thus we get a clear idea of all the stable and unstable situations around the Maxwell-Boltzmann approach. Thus the current theory is given a mathematical extension and physical interpretations can be found to situations in (1) and (2). Incidently Tsallis statistics is a special case of (1) for γ = 0, a = 1, δ = 1, η = 1. The Beck-Cohen superstatistics, discussed in current statistical mechanics literature is a special case of (2) for a = 1, η = 1, α > 1. The main purpose of the present paper is to investigate in some more detail, mathematically, the extended thermonuclear functions for Maxwell-Boltzmann statistics and in the cut-off case. The extended thermonuclear functions will be evaluated in closed form for all convenient values of the parameter by means of residue calculus. A comparison of the standard thermonuclear functions with the extended thermonuclear functions is also done. The results and derivations in this paper are new and these will be of interest to physicists, mathematicians, probabilists, and statisticians.

  12. CONTROL ROD FOR A NUCLEAR REACTOR AND METHOD OF PREPARATION

    DOEpatents

    Hausner, H.H.

    1958-12-30

    BS>An improved control rod is presented for a nuclear reactor. This control rod is comprised of a rare earth metal oxide or rare earth metal carbide such as gadolinium oxide or gadolinium carbide, uniformly distributed in a metal matrix having a low cross sectional area of absorption for thermal neutrons, such as aluminum, beryllium, and zirconium.

  13. SPERTI plot plan, showing reactor and control areas after 1956 ...

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

    SPERT-I plot plan, showing reactor and control areas after 1956 addition to PER-601. Includes reactor-area buildings PER-605, -606, and -607; Terminal Building (PER-604), and control-area buildings PER-601, -602, -603 along with associated parking areas and fencing. Vicinity map shows relationship of SPERT-I to SPERT-II, SPERT-III, central facilities area (at west end of E. Portland Avenue) and Highways 20 and 26. Idaho Operations Office PER-103-IDO-1. Date: December 1955. INEEL index no. 760-0103-396-109112 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

  14. Nuclear reactor remote disconnect control rod coupling indicator

    DOEpatents

    Vuckovich, Michael

    1977-01-01

    A coupling indicator for use with nuclear reactor control rod assemblies which have remotely disengageable couplings between the control rod and the control rod drive shaft. The coupling indicator indicates whether the control rod and the control rod drive shaft are engaged or disengaged. A resistive network, utilizing magnetic reed switches, senses the position of the control rod drive mechanism lead screw and the control rod position indicating tube, and the relative position of these two elements with respect to each other is compared to determine whether the coupling is engaged or disengaged.

  15. Temperature controlled material irradiation in the advanced test reactor

    SciTech Connect

    Furstenau, R.V.; Ingrahm, F.W.

    1995-12-31

    The Advanced Test Reactor (ATR) is located at the Idaho National Engineering Laboratory (INEL) near Idaho Falls, Idaho, USA and is owned and regulated by the U.S. Department of Energy (US DOE). The ATR is operated for the US DOE by Lockheed Martin Idaho Technologies. In recent years, prime irradiation space in the ATR has been made available for use by customers having irradiation service needs in addition to the reactor`s principal user, the U.S. Naval Nuclear Propulsion Program. To enhance the reactor`s capabilities, the US DOE has initiated the development of an Irradiation Test Vehicle (ITV) capable of providing neutron spectral tailoring and temperature control for up to 28 experiments. The ATR-ITV will have the flexibility to simultaneously support a variety of experiments requiring fast, thermal or mixed spectrum neutron environments. Temperature control is accomplished by varying the thermal conductivity across a gas gap established between the experiment specimen capsule wall and the experiment `in-pile tube (IPT)` inside diameter. Thermal conductivity is adjusted by alternating the control gas mixture ratio of two gases with different thermal conductivities.

  16. Artificial Intelligent Control for a Novel Advanced Microwave Biodiesel Reactor

    NASA Astrophysics Data System (ADS)

    Wali, W. A.; Hassan, K. H.; Cullen, J. D.; Al-Shamma'a, A. I.; Shaw, A.; Wylie, S. R.

    2011-08-01

    Biodiesel, an alternative diesel fuel made from a renewable source, is produced by the transesterification of vegetable oil or fat with methanol or ethanol. In order to control and monitor the progress of this chemical reaction with complex and highly nonlinear dynamics, the controller must be able to overcome the challenges due to the difficulty in obtaining a mathematical model, as there are many uncertain factors and disturbances during the actual operation of biodiesel reactors. Classical controllers show significant difficulties when trying to control the system automatically. In this paper we propose a comparison of artificial intelligent controllers, Fuzzy logic and Adaptive Neuro-Fuzzy Inference System(ANFIS) for real time control of a novel advanced biodiesel microwave reactor for biodiesel production from waste cooking oil. Fuzzy logic can incorporate expert human judgment to define the system variables and their relationships which cannot be defined by mathematical relationships. The Neuro-fuzzy system consists of components of a fuzzy system except that computations at each stage are performed by a layer of hidden neurons and the neural network's learning capability is provided to enhance the system knowledge. The controllers are used to automatically and continuously adjust the applied power supplied to the microwave reactor under different perturbations. A Labview based software tool will be presented that is used for measurement and control of the full system, with real time monitoring.

  17. CADMIUM-RARE EARTH BORATE GLASS AS REACTOR CONTROL MATERIAL

    DOEpatents

    Ploetz, G.L.; Ray, W.E.

    1958-11-01

    A reactor control rod fabricated from a cadmiumrare earth-borate glass is presented. The rare earth component of this glass is selected from among those rare earths having large neutron capture cross sections, such as samarium, gadolinium or europium. Partlcles of this glass are then dispersed in a metal matrix by standard powder metallurgy techniques.

  18. Automatic coolant flow control device for a nuclear reactor assembly

    DOEpatents

    Hutter, E.

    1984-01-27

    A device which controls coolant flow through a nuclear reactor assembly comprises a baffle means at the exit end of said assembly having a plurality of orifices, and a bimetallic member in operative relation to the baffle means such that at increased temperatures said bimetallic member deforms to unblock some of said orifices and allow increased coolant flow therethrough.

  19. Method of controlling crystallite size in nuclear-reactor fuels

    DOEpatents

    Lloyd, Milton H.; Collins, Jack L.; Shell, Sam E.

    1985-01-01

    Improved spherules for making enhanced forms of nuclear-reactor fuels are prepared by internal gelation procedures within a sol-gel operation and are accomplished by first boiling the concentrated HMTA-urea feed solution before engaging in the spherule-forming operation thereby effectively controlling crystallite size in the product spherules.

  20. Method of controlling crystallite size in nuclear-reactor fuels

    DOEpatents

    Lloyd, M.H.; Collins, J.L.; Shell, S.E.

    Improved spherules for making enhanced forms of nuclear-reactor fuels are prepared by internal gelation procedures within a sol-gel operation and are accomplished by first boiling the concentrated HMTA-urea feed solution before engaging in the spherule-forming operation thereby effectively controlling crystallite size in the product spherules.

  1. Neutron Stars and Thermonuclear X-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, Supid

    2007-01-01

    This viewgraph presentation describes neutron stars and thermonuclear x ray bursts. The contents include: 1) Neutron Stars: why do we care?; 2) Thermonuclear Bursts: why do we care?; 3) Neutron Stars: Mass, Radius and Spin: a. Continuum Spectroscopy of Bursts b. Spectral Lines from Bursts c. Timing Properties of Bursts; 4) Neutron Star Atmosphere: Thermonuclear Flame Spreading; and 5) Future Prospects and Conclusions.

  2. Thermonuclear milestones: (1) The American effort

    SciTech Connect

    Goncharov, G.A.

    1996-11-01

    It took a decade for scientists in America to develop the first ideas for a {open_quote}Super{close_quote} bomb into a device that ignited {open_quote}the first small thermonuclear flame ever to burn on Earth.{close_quote} {copyright} {ital 1996 American Institute of Physics.}

  3. Enabling autonomous control for space reactor power systems

    SciTech Connect

    Wood, R. T.

    2006-07-01

    The application of nuclear reactors for space power and/or propulsion presents some unique challenges regarding the operations and control of the power system. Terrestrial nuclear reactors employ varying degrees of human control and decision-making for operations and benefit from periodic human interaction for maintenance. In contrast, the control system of a space reactor power system (SRPS) employed for deep space missions must be able to accommodate unattended operations due to communications delays and periods of planetary occlusion while adapting to evolving or degraded conditions with no opportunity for repair or refurbishment. Thus, a SRPS control system must provide for operational autonomy. Oak Ridge National Laboratory (ORNL) has conducted an investigation of the state of the technology for autonomous control to determine the experience base in the nuclear power application domain, both for space and terrestrial use. It was found that control systems with varying levels of autonomy have been employed in robotic, transportation, spacecraft, and manufacturing applications. However, autonomous control has not been implemented for an operating terrestrial nuclear power plant nor has there been any experience beyond automating simple control loops for space reactors. Current automated control technologies for nuclear power plants are reasonably mature, and basic control for a SRPS is clearly feasible under optimum circumstances. However, autonomous control is primarily intended to account for the non optimum circumstances when degradation, failure, and other off-normal events challenge the performance of the reactor and near-term human intervention is not possible. Thus, the development and demonstration of autonomous control capabilities for the specific domain of space nuclear power operations is needed. This paper will discuss the findings of the ORNL study and provide a description of the concept of autonomy, its key characteristics, and a prospective

  4. VARIABLE AREA CONTROL ROD FOR NUCLEAR REACTOR

    DOEpatents

    Huston, N.E.

    1960-05-01

    A control rod is described which permits continual variation of its absorbing strength uniformly along the length of the rod. The rod is fail safe and is fully inserted into the core but changes in its absorbing strength do not produce axial flux distortion. The control device comprises a sheet containing a material having a high thermal-neutron absorption cross section. A pair of shafts engage the sheet along the longitudinal axis of the shafts and gears associated with the shafts permit winding and unwinding of the sheet around the shafts.

  5. Spectrophotometric Procedure for Fast Reactor Advanced Coolant Manufacture Control

    NASA Astrophysics Data System (ADS)

    Andrienko, O. S.; Egorov, N. B.; Zherin, I. I.; Indyk, D. V.

    2016-01-01

    The paper describes a spectrophotometric procedure for fast reactor advanced coolant manufacture control. The molar absorption coefficient of dimethyllead dibromide with dithizone was defined as equal to 68864 ± 795 l·mole-1·cm-1, limit of detection as equal to 0.583 · 10-6 g/ml. The spectrophotometric procedure application range was found to be equal to 37.88 - 196.3 g. of dimethyllead dibromide in the sample. The procedure was used within the framework of the development of the method of synthesis of the advanced coolant for fast reactors.

  6. Hydraulic balancing of a control component within a nuclear reactor

    DOEpatents

    Marinos, D.; Ripfel, H.C.F.

    1975-10-14

    A reactor control component includes an inner conduit, for instance containing neutron absorber elements, adapted for longitudinal movement within an outer guide duct. A transverse partition partially encloses one end of the conduit and meets a transverse wall within the guide duct when the conduit is fully inserted into the reactor core. A tube piece extends from the transverse partition and is coaxially aligned to be received within a tubular receptacle which extends from the transverse wall. The tube piece and receptacle cooperate in engagement to restrict the flow and pressure of coolant beneath the transverse partition and thereby minimize upward forces tending to expel the inner conduit.

  7. Fabrication of control rods for the High Flux Isotope Reactor

    SciTech Connect

    Sease, J.D.

    1998-03-01

    The High Flux Isotope Reactor (HFIR) is a research-type nuclear reactor that was designed and built in the early 1960s and has been in continuous operation since its initial criticality in 1965. Under current plans, the HFIR is expected to continue in operation until 2035. This report updates ORNL/TM-9365, Fabrication Procedure for HFIR Control Plates, which was mainly prepared in the early 1970's but was not issued until 1984, and reflects process changes, lessons learned in the latest control rod fabrication campaign, and suggested process improvements to be considered in future campaigns. Most of the personnel involved with the initial development of the processes and in part campaigns have retired or will retire soon. Because their unlikely availability in future campaigns, emphasis has been placed on providing some explanation of why the processes were selected and some discussions about the importance of controlling critical process parameters. Contained in this report is a description of the function of control rods in the reactor, the brief history of the development of control rod fabrication processes, and a description of procedures used in the fabrication of control rods. A listing of the controlled documents and procedures used in the last fabrication campaigns is referenced in Appendix A.

  8. Slow control systems of the Reactor Experiment for Neutrino Oscillation

    NASA Astrophysics Data System (ADS)

    Choi, J. H.; Jang, H. I.; Choi, W. Q.; Choi, Y.; Jang, J. S.; Jeon, E. J.; Joo, K. K.; Kim, B. R.; Kim, H. S.; Kim, J. Y.; Kim, S. B.; Kim, S. Y.; Kim, W.; Kim, Y. D.; Ko, Y. J.; Lee, J. K.; Lim, I. T.; Pac, M. Y.; Park, I. G.; Park, J. S.; Park, R. G.; Seo, H. K.; Seo, S. H.; Shin, C. D.; Siyeon, K.; Yeo, I. S.; Yu, I.

    2016-02-01

    The RENO experiment has been in operation since August 2011 to measure reactor antineutrino disappearance using identical near and far detectors. For accurate measurements of neutrino mixing parameters and efficient data taking, it is crucial to monitor and control the detector in real time. Environmental conditions also need to be monitored for stable operation of detectors as well as for safety reasons. In this paper, we report the design, hardware, operation, and performance of the slow control system.

  9. Condensed hydrogen for thermonuclear fusion

    SciTech Connect

    Kucheyev, S. O.; Hamza, A. V.

    2010-11-15

    Inertial confinement fusion (ICF) power, in either pure fusion or fission-fusion hybrid reactors, is a possible solution for future world's energy demands. Formation of uniform layers of a condensed hydrogen fuel in ICF targets has been a long standing materials physics challenge. Here, we review the progress in this field. After a brief discussion of the major ICF target designs and the basic properties of condensed hydrogens, we review both liquid and solid layering methods, physical mechanisms causing layer nonuniformity, growth of hydrogen single crystals, attempts to prepare amorphous and nanostructured hydrogens, and mechanical deformation behavior. Emphasis is given to current challenges defining future research areas in the field of condensed hydrogens for fusion energy applications.

  10. Autonomous Control Capabilities for Space Reactor Power Systems

    NASA Astrophysics Data System (ADS)

    Wood, Richard T.; Neal, John S.; Brittain, C. Ray; Mullens, James A.

    2004-02-01

    The National Aeronautics and Space Administration's (NASA's) Project Prometheus, the Nuclear Systems Program, is investigating a possible Jupiter Icy Moons Orbiter (JIMO) mission, which would conduct in-depth studies of three of the moons of Jupiter by using a space reactor power system (SRPS) to provide energy for propulsion and spacecraft power for more than a decade. Terrestrial nuclear power plants rely upon varying degrees of direct human control and interaction for operations and maintenance over a forty to sixty year lifetime. In contrast, an SRPS is intended to provide continuous, remote, unattended operation for up to fifteen years with no maintenance. Uncertainties, rare events, degradation, and communications delays with Earth are challenges that SRPS control must accommodate. Autonomous control is needed to address these challenges and optimize the reactor control design. In this paper, we describe an autonomous control concept for generic SRPS designs. The formulation of an autonomous control concept, which includes identification of high-level functional requirements and generation of a research and development plan for enabling technologies, is among the technical activities that are being conducted under the U.S. Department of Energy's Space Reactor Technology Program in support of the NASA's Project Prometheus. The findings from this program are intended to contribute to the successful realization of the JIMO mission.

  11. Autonomous Control Capabilities for Space Reactor Power Systems

    SciTech Connect

    Wood, Richard T.; Neal, John S.; Brittain, C. Ray; Mullens, James A.

    2004-02-04

    The National Aeronautics and Space Administration's (NASA's) Project Prometheus, the Nuclear Systems Program, is investigating a possible Jupiter Icy Moons Orbiter (JIMO) mission, which would conduct in-depth studies of three of the moons of Jupiter by using a space reactor power system (SRPS) to provide energy for propulsion and spacecraft power for more than a decade. Terrestrial nuclear power plants rely upon varying degrees of direct human control and interaction for operations and maintenance over a forty to sixty year lifetime. In contrast, an SRPS is intended to provide continuous, remote, unattended operation for up to fifteen years with no maintenance. Uncertainties, rare events, degradation, and communications delays with Earth are challenges that SRPS control must accommodate. Autonomous control is needed to address these challenges and optimize the reactor control design. In this paper, we describe an autonomous control concept for generic SRPS designs. The formulation of an autonomous control concept, which includes identification of high-level functional requirements and generation of a research and development plan for enabling technologies, is among the technical activities that are being conducted under the U.S. Department of Energy's Space Reactor Technology Program in support of the NASA's Project Prometheus. The findings from this program are intended to contribute to the successful realization of the JIMO mission.

  12. COAXIAL CONTROL ROD DRIVE MECHANISM FOR NEUTRONIC REACTORS

    DOEpatents

    Fox, R.J.; Oakes, L.C.

    1959-04-14

    A drive mechanism is presented for the control rod or a nuclear reactor. In this device the control rod is coupled to a drive shaft which extends coaxially through the rotor of an electric motor for relative rotation with respect thereto. A gear reduction mehanism is coupled between the rotor and the drive shaft to convert the rotary motion of the motor into linear motion of the shaft with a comparatively great reduction in speed, thereby providing relatively glow linear movement of the shaft and control rod for control purposes.

  13. Merging white dwarfs and thermonuclear supernovae.

    PubMed

    van Kerkwijk, M H

    2013-06-13

    Thermonuclear supernovae result when interaction with a companion reignites nuclear fusion in a carbon-oxygen white dwarf, causing a thermonuclear runaway, a catastrophic gain in pressure and the disintegration of the whole white dwarf. It is usually thought that fusion is reignited in near-pycnonuclear conditions when the white dwarf approaches the Chandrasekhar mass. I briefly describe two long-standing problems faced by this scenario, and the suggestion that these supernovae instead result from mergers of carbon-oxygen white dwarfs, including those that produce sub-Chandrasekhar-mass remnants. I then turn to possible observational tests, in particular, those that test the absence or presence of electron captures during the burning. PMID:23630372

  14. Merging white dwarfs and thermonuclear supernovae.

    PubMed

    van Kerkwijk, M H

    2013-06-13

    Thermonuclear supernovae result when interaction with a companion reignites nuclear fusion in a carbon-oxygen white dwarf, causing a thermonuclear runaway, a catastrophic gain in pressure and the disintegration of the whole white dwarf. It is usually thought that fusion is reignited in near-pycnonuclear conditions when the white dwarf approaches the Chandrasekhar mass. I briefly describe two long-standing problems faced by this scenario, and the suggestion that these supernovae instead result from mergers of carbon-oxygen white dwarfs, including those that produce sub-Chandrasekhar-mass remnants. I then turn to possible observational tests, in particular, those that test the absence or presence of electron captures during the burning.

  15. Epidemiology of a thermonuclear bomb-burst over Nashville, Tennessee: a theoretic study.

    PubMed

    Quinn, R W

    1983-07-01

    A thermonuclear bomb explosion over any city in the world would have a devastating effect on the population and environment. For those who survive, with or without injuries, life would become primitive with little or no uncontaminated food or water, and with inadequate housing, fuel, and medical care, resulting in a breakdown of family and interpersonal relationships. This theoretic study of the potential outcome of a thermonuclear bomb-burst over Nashville, Tennessee, discusses epidemiologically the wide range of medical and psychologic effects from the direct trauma of blast and fire, widespread epidemics of otherwise controlled disease, long-term chronic illness, genetic damage, and catastrophic environmental havoc.

  16. System and method for air temperature control in an oxygen transport membrane based reactor

    DOEpatents

    Kelly, Sean M

    2016-09-27

    A system and method for air temperature control in an oxygen transport membrane based reactor is provided. The system and method involves introducing a specific quantity of cooling air or trim air in between stages in a multistage oxygen transport membrane based reactor or furnace to maintain generally consistent surface temperatures of the oxygen transport membrane elements and associated reactors. The associated reactors may include reforming reactors, boilers or process gas heaters.

  17. (Man-machine interface of computer controlled reactors)

    SciTech Connect

    Knee, H.E.

    1989-11-10

    The traveler and Mr. J.D. White, also of ORNL, met with management and research personnel at the Halden Reactor Project (HRP) in Halden, Norway to assess the potential for future collaborative research between ORNL and the HRP in the areas of advanced controls and man-machine interface. The travelers were provided with two-and-a-half days of briefings and demonstrations that addressed a number of computer-oriented support systems (COSSs) and an integrated surveillance and control system (ISACS). The purpose of the ISACs is to integrate the various COSSs into a super'' support environment for the human operator of a nuclear power plant. The HRP has not only developed a number of COSSs over the past decade, it has also built an experimental environment in which to evaluate the emerging support systems, and to examine the impact on human performance. Most of their research has focused on nuclear-oriented informational displays for the operator, with little to no emphasis on control. The Halden experimental environment and expertise in displays, coupled with ORNL's recognized expertise in the area of advanced controls, could provide strong control system/room design support for DOE's Advanced Reactor Designs, especially the Advanced Liquid Metal Concept.

  18. Control of reactor coolant flow path during reactor decay heat removal

    DOEpatents

    Hunsbedt, Anstein N.

    1988-01-01

    An improved reactor vessel auxiliary cooling system for a sodium cooled nuclear reactor is disclosed. The sodium cooled nuclear reactor is of the type having a reactor vessel liner separating the reactor hot pool on the upstream side of an intermediate heat exchanger and the reactor cold pool on the downstream side of the intermediate heat exchanger. The improvement includes a flow path across the reactor vessel liner flow gap which dissipates core heat across the reactor vessel and containment vessel responsive to a casualty including the loss of normal heat removal paths and associated shutdown of the main coolant liquid sodium pumps. In normal operation, the reactor vessel cold pool is inlet to the suction side of coolant liquid sodium pumps, these pumps being of the electromagnetic variety. The pumps discharge through the core into the reactor hot pool and then through an intermediate heat exchanger where the heat generated in the reactor core is discharged. Upon outlet from the heat exchanger, the sodium is returned to the reactor cold pool. The improvement includes placing a jet pump across the reactor vessel liner flow gap, pumping a small flow of liquid sodium from the lower pressure cold pool into the hot pool. The jet pump has a small high pressure driving stream diverted from the high pressure side of the reactor pumps. During normal operation, the jet pumps supplement the normal reactor pressure differential from the lower pressure cold pool to the hot pool. Upon the occurrence of a casualty involving loss of coolant pump pressure, and immediate cooling circuit is established by the back flow of sodium through the jet pumps from the reactor vessel hot pool to the reactor vessel cold pool. The cooling circuit includes flow into the reactor vessel liner flow gap immediate the reactor vessel wall and containment vessel where optimum and immediate discharge of residual reactor heat occurs.

  19. Heterogeneous Nuclear Reactor Models for Optimal Xenon Control.

    NASA Astrophysics Data System (ADS)

    Gondal, Ishtiaq Ahmad

    Nuclear reactors are generally modeled as homogeneous mixtures of fuel, control, and other materials while in reality they are heterogeneous-homogeneous configurations comprised of fuel and control rods along with other materials. Similarly, for space-time studies of a nuclear reactor, homogeneous, usually one-group diffusion theory, models are used, and the system equations are solved by either nodal or modal expansion approximations. Study of xenon-induced problems has also been carried out using similar models and with the help of dynamic programming or classical calculus of variations or the minimum principle. In this study a thermal nuclear reactor is modeled as a two-dimensional lattice of fuel and control rods placed in an infinite-moderator in plane geometry. The two-group diffusion theory approximation is used for neutron transport. Space -time neutron balance equations are written for two groups and reduced to one space-time algebraic equation by using the two-dimensional Fourier transform. This equation is written at all fuel and control rod locations. Iodine -xenon and promethium-samarium dynamic equations are also written at fuel rod locations only. These equations are then linearized about an equilibrium point which is determined from the steady-state form of the original nonlinear system equations. After studying poisonless criticality, with and without control, and the stability of the open-loop system and after checking its controllability, a performance criterion is defined for the xenon-induced spatial flux oscillation problem in the form of a functional to be minimized. Linear -quadratic optimal control theory is then applied to solve the problem. To perform a variety of different additional useful studies, this formulation has potential for various extensions and variations; for example, different geometry of the problem, with possible extension to three dimensions, heterogeneous -homogeneous formulation to include, for example, homogeneously

  20. [Stability control of aerobic granules using an innovative reactor].

    PubMed

    Li, Zhi-Hua; Yang, Fan; Li, Sheng; Xie, Lei; Wang, Xiao-Chang

    2012-06-01

    Uncontrolled variation of diameter and density of aerobic granules frequently resulted in instability and thus brought about operation failure. An innovative reactor was therefore developed for the control of diameter and density of aerobic granules. There were two ways to select the sludge, one was the short settling time select the big and dense granules in the reactor, and the other was the hydro cyclone that washed out the big and compact granules preventing big and compact fourthly growth in the reactor. By these means, the diameter of granules could maintained in the range of 300-1 000 microm for a long time, consequently, the long term stability could be obtained. According to the kinetic analysis, it was found that the energy maintenance coefficient was 0.08-0.10, which was much higher than the conventional granular system (0.06), and the ratio of the COD used for maintenance to the influent was higher than the conventional one. Additionally, the removal efficiencies of COD and ammonia were 92% and 60%, respectively.

  1. Plasma transport control and self-sustaining fusion reactor

    SciTech Connect

    Ono, M.; Peng, Yueng Kay Martin

    1997-01-01

    The possibility of a high-performance/low-cost fusion reactor concept which can simultaneously satisfy (1) high beta, (2) high bootstrap fractio (self-sustaining) and (3) high confinement is discussed. In CDX-U, a tokamak configuration was created and sustained solely by internally generated bootstrap currents, in which a seed current is created through a nonclassical current diffusion process. Recent theoretical studies of MHD stability limits in spherical tori [e.g. the National Spherical Torus Experiment (NSTX)] produced a promising regime with stable beta of 45% and bootstrap current fraction of > 99%. Since the bootstrap current is generated by the pressure gradient, to satisfy the needed current profile for MHD stable high beta regimes, it is essential to develop a means to control the pressure profile. It is suggested that the most efficient approach for pressure profile control is through the creation of transport barriers (localized regions of low plasma transport) in the plasma. As a tool for creating the core transport barrier, poloidal-sheared-flow generation by ion Bernstein waves (IBW) near the wave absorption region appears to be promising. In PBX-M, application of IBW power produced a high-quality internal transport barrier where the ion energy and particle transport became neoclassical in the barrier region. The observation is consistent with the IBW-inducedpoloidal- sheared-flow model. An experiment is planned on TFTR to demonstrate this concept with D T reactor-grade plasmas. For edge transport control, a method based on electron ripple injection (ERI), driven by electron cyclotron heating (ECH), is being developed on CDX-U. It is estimated that both the IBW and ERI methods can create a transport barrier in reactor-grade plasmas (e.g. ITER) with a relatively small amount of power ( 10 MW Pfusion).

  2. Plasma transport control and self-sustaining fusion reactor

    SciTech Connect

    Ono, M.; Bell, R.; Choe, W.

    1997-02-01

    The possibility of a high performance/low cost fusion reactor concept which can simultaneously satisfy (1) high beta, (2) high bootstrap fraction (self-sustaining), and (3) high confinement is discussed. In CDX-U, a tokamak configuration was created and sustained solely by internally generated bootstrap currents, in which a seed current is created through a non-classical current diffusion process. Recent theoretical studies of MHD stability limits in spherical torus [e.g., the National Spherical Torus Experiment (NSTX)] produced a promising regime with stable beta of 45% and bootstrap current fraction of {ge}99%. Since the bootstrap current is generated by the pressure gradient, to satisfy the needed current profile for MHD stable high beta regimes, it is essential to develop a means to control the pressure profile. It is suggested that the most efficient approach for pressure profile control is through a creation of transport barriers (localized regions of low plasma transport) in the plasma. As a tool for creating the core transport barrier, poloidal-sheared-flow generation by ion Bernstein waves (IBW) near the wave absorption region appears to be promising. In PBX-M, application of IBW power produced a high-quality internal transport barrier where the ion energy and particle transport became neoclassical in the barrier region. The observation is consistent with the IBW-induced-poloidal-sheared-flow model. An experiment is planned on TFTR to demonstrate this concept with D-T reactor-grade plasmas. For edge transport control, a method based on electron ripple injection (ERI), driven by electron cyclotron heating (ECH), is being developed on CDX-U. It is estimated that both the IBW and ERI methods can create a transport barrier in reactor-grade plasmas (e.g., ITER) with a relatively small amount of power ({approx}10 MW {much_lt} P{sub fusion}).

  3. Real-time, multitasking control system for reactor inspection robots

    SciTech Connect

    Byrne, T.J.; Jenkins, J.B.; Lewis, W.I.; Park, L.R.; Reeves, G.E.

    1988-01-01

    The Equipment Engineering Division of the Department of Energy's Savannah River Laboratory in Aiken, South Carolina has developed a remote system to perform ultrasonic (UT) and eddy current (ET) wall weld inspections inside the nuclear reactors at the site. The basic components of the inspection system include an inspection robot and control hardware, a supervisory computer, and ultrasonic and eddy current data collection and analysis computers. The ultrasonic and eddy current systems are responsible for driving the transducers, and digitizing, displaying, and storing the information. 7 figs.

  4. NEUTRONIC REACTOR CONTROL ROD AND METHOD OF FABRICATION

    DOEpatents

    Porembka, S.W. Jr.

    1961-06-27

    A reactor control rod formed from a compacted powder dispersion is patented. The rod consists of titanium sheathed with a cladding alloy. The cladding alloy contains 1.3% to 1.6% by weight of tin, 0.07% to 0.12% by weight of chromium, 0.04% to 0.08% by weight of nickel, 0.09% to 0.16% by weight of iron, carbon not exceeding 0.05%, less than 0.5% by weight of incidental impurities, and the balance zirconium.

  5. Compton scattering in ignited thermonuclear plasmas.

    PubMed

    Hartemann, F V; Siders, C W; Barty, C P J

    2008-03-28

    Inertially confined, ignited thermonuclear D-T plasmas will produce intense blackbody radiation at temperatures T greater, similar20 keV; it is shown that the injection of GeV electrons into the burning core can efficiently generate high-energy Compton scattering photons. Moreover, the spectrum scattered in a small solid angle can be remarkably monochromatic, due to kinematic pileup; a peak brightness in excess of 10;{30} photons/(mm(2) mrad(2) s 0.1% bandwidth) is predicted. These results are discussed within the context of the Schwinger field and the Sunyaev-Zel'dovich effect.

  6. Controlled multistep synthesis in a three-phase droplet reactor

    PubMed Central

    Nightingale, Adrian M.; Phillips, Thomas W.; Bannock, James H.; de Mello, John C.

    2014-01-01

    Channel-fouling is a pervasive problem in continuous flow chemistry, causing poor product control and reactor failure. Droplet chemistry, in which the reaction mixture flows as discrete droplets inside an immiscible carrier liquid, prevents fouling by isolating the reaction from the channel walls. Unfortunately, the difficulty of controllably adding new reagents to an existing droplet stream has largely restricted droplet chemistry to simple reactions in which all reagents are supplied at the time of droplet formation. Here we describe an effective method for repeatedly adding controlled quantities of reagents to droplets. The reagents are injected into a multiphase fluid stream, comprising the carrier liquid, droplets of the reaction mixture and an inert gas that maintains a uniform droplet spacing and suppresses new droplet formation. The method, which is suited to many multistep reactions, is applied to a five-stage quantum dot synthesis wherein particle growth is sustained by repeatedly adding fresh feedstock. PMID:24797034

  7. CRDIAC: Coupled Reactor Depletion Instrument with Automated Control

    SciTech Connect

    Steven K. Logan

    2012-08-01

    When modeling the behavior of a nuclear reactor over time, it is important to understand how the isotopes in the reactor will change, or transmute, over that time. This is especially important in the reactor fuel itself. Many nuclear physics modeling codes model how particles interact in the system, but do not model this over time. Thus, another code is used in conjunction with the nuclear physics code to accomplish this. In our code, Monte Carlo N-Particle (MCNP) codes and the Multi Reactor Transmutation Analysis Utility (MRTAU) were chosen as the codes to use. In this way, MCNP would produce the reaction rates in the different isotopes present and MRTAU would use cross sections generated from these reaction rates to determine how the mass of each isotope is lost or gained. Between these two codes, the information must be altered and edited for use. For this, a Python 2.7 script was developed to aid the user in getting the information in the correct forms. This newly developed methodology was called the Coupled Reactor Depletion Instrument with Automated Controls (CRDIAC). As is the case in any newly developed methodology for modeling of physical phenomena, CRDIAC needed to be verified against similar methodology and validated against data taken from an experiment, in our case AFIP-3. AFIP-3 was a reduced enrichment plate type fuel tested in the ATR. We verified our methodology against the MCNP Coupled with ORIGEN2 (MCWO) method and validated our work against the Post Irradiation Examination (PIE) data. When compared to MCWO, the difference in concentration of U-235 throughout Cycle 144A was about 1%. When compared to the PIE data, the average bias for end of life U-235 concentration was about 2%. These results from CRDIAC therefore agree with the MCWO and PIE data, validating and verifying CRDIAC. CRDIAC provides an alternative to using ORIGEN-based methodology, which is useful because CRDIAC's depletion code, MRTAU, uses every available isotope in its depletion

  8. Overview of the US program of controls for advanced reactors

    SciTech Connect

    White, J.D.; Sackett, J.I.; Monson, R.; Lindsay, R.W.; Carroll, D.G.

    1989-01-01

    An automated control system can incorporate control goals and strategies, assessment of present and future plant status, diagnostic evaluation and maintenance planning, and signal and command validation. It has not been feasible to employ these capabilities in conventional hard-wired, analog, control systems. Recent advances in computer-based digital data acquisition systems, process controllers, fiber-optic signal transmission artificial intelligence tools and methods, and small inexpensive, fast, large-capacity computers---with both numeric and symbolic capabilities---have provided many of the necessary ingredients for developing large, practical automated control systems. Furthermore, recent reactor designs which provide strong passive responses to operational upsets or accidents afford good opportunities to apply these advances in control technology. This paper presents an overall US national perspective for advanced controls research and development. The goals of high reliability, low operating cost and simple operation are described. The staged approach from conceptualization through implementation is discussed. Then the paper describes the work being done by ORNL, ANL and GE. The relationship of this work to the US commercial industry is also discussed.

  9. 156. ARAIII Reactor building (ARA608) Electrical and control details of ...

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

    156. ARA-III Reactor building (ARA-608) Electrical and control details of mobile work bridge over reactor and pipiing pits. Aerojet-general 880-area/GCRE-608-E-6. Date: November 1958. Ineel index code no. 063-0608-10-013-102621. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

  10. Compatibility of refractory materials for nuclear reactor poison control systems

    NASA Technical Reports Server (NTRS)

    Sinclair, J. H.

    1974-01-01

    Metal-clad poison rods have been considered for the control system of an advanced space power reactor concept studied at the NASA Lewis Research Center. Such control rods may be required to operate at temperatures of about 140O C. Selected poison materials (including boron carbide and the diborides of zirconium, hafnium, and tantalum) were subjected to 1000-hour screening tests in contact with candidate refractory metal cladding materials (including tungsten and alloys of tantalum, niobium, and molybdenum) to assess the compatibility of these materials combinations at the temperatures of interest. Zirconium and hafnium diborides were compatible with refractory metals at 1400 C, but boron carbide and tantalum diboride reacted with the refractory metals at this temperature. Zirconium diboride also showed promise as a reaction barrier between boron carbide and tungsten.

  11. International Thermonuclear Experimental Reactor (ITER) neutral beam design

    SciTech Connect

    Myers, T.J.; Brook, J.W.; Spampinato, P.T.; Mueller, J.P.; Luzzi, T.E.; Sedgley, D.W. . Space Systems Div.)

    1990-10-01

    This report discusses the following topics on ITER neutral beam design: ion dump; neutralizer and module gas flow analysis; vacuum system; cryogenic system; maintainability; power distribution; and system cost.

  12. Alternative approaches to fusion. [reactor design and reactor physics for Tokamak fusion reactors

    NASA Technical Reports Server (NTRS)

    Roth, R. J.

    1976-01-01

    The limitations of the Tokamak fusion reactor concept are discussed and various other fusion reactor concepts are considered that employ the containment of thermonuclear plasmas by magnetic fields (i.e., stellarators). Progress made in the containment of plasmas in toroidal devices is reported. Reactor design concepts are illustrated. The possibility of using fusion reactors as a power source in interplanetary space travel and electric power plants is briefly examined.

  13. Supervisory Control System Architecture for Advanced Small Modular Reactors

    SciTech Connect

    Cetiner, Sacit M; Cole, Daniel L; Fugate, David L; Kisner, Roger A; Melin, Alexander M; Muhlheim, Michael David; Rao, Nageswara S; Wood, Richard Thomas

    2013-08-01

    This technical report was generated as a product of the Supervisory Control for Multi-Modular SMR Plants project within the Instrumentation, Control and Human-Machine Interface technology area under the Advanced Small Modular Reactor (SMR) Research and Development Program of the U.S. Department of Energy. The report documents the definition of strategies, functional elements, and the structural architecture of a supervisory control system for multi-modular advanced SMR (AdvSMR) plants. This research activity advances the state-of-the art by incorporating decision making into the supervisory control system architectural layers through the introduction of a tiered-plant system approach. The report provides a brief history of hierarchical functional architectures and the current state-of-the-art, describes a reference AdvSMR to show the dependencies between systems, presents a hierarchical structure for supervisory control, indicates the importance of understanding trip setpoints, applies a new theoretic approach for comparing architectures, identifies cyber security controls that should be addressed early in system design, and describes ongoing work to develop system requirements and hardware/software configurations.

  14. Demonstration of thermonuclear conditions in magnetized liner inertial fusion experiments

    DOE PAGESBeta

    Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Hahn, Kelly D.; Hansen, Stephanie B.; Knapp, Patrick F.; Schmit, Paul F.; Ruiz, Carlos L.; Sinars, Daniel Brian; Harding, Eric C.; et al

    2015-04-29

    In this study, the magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas17, 056303 (2010)] utilizes a magnetic field and laser heating to relax the pressure requirements of inertial confinement fusion. The first experiments to test the concept [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] were conducted utilizing the 19 MA, 100 ns Z machine, the 2.5 kJ, 1 TW Z Beamlet laser, and the 10 T Applied B-field on Z system. Despite an estimated implosion velocity of only 70 km/s in these experiments, electron and ion temperatures at stagnation were as highmore » as 3 keV, and thermonuclear deuterium-deuterium neutron yields up to 2 × 1012 have been produced. X-ray emission from the fuel at stagnation had widths ranging from 50 to 110 μm over a roughly 80% of the axial extent of the target (6–8 mm) and lasted approximately 2 ns. X-ray yields from these experiments are consistent with a stagnation density of the hot fuel equal to 0.2–0.4 g/cm3. In these experiments, up to 5 ×1010 secondary deuterium-tritium neutrons were produced. Given that the areal density of the plasma was approximately 1–2 mg/cm2, this indicates the stagnation plasma was significantly magnetized, which is consistent with the anisotropy observed in the deuterium-tritium neutron spectra. Control experiments where the laser and/or magnetic field were not utilized failed to produce stagnation temperatures greater than 1 keV and primary deuterium-deuterium yields greater than 1010. An additional control experiment where the fuel contained a sufficient dopant fraction to substantially increase radiative losses also failed to produce a relevant stagnation temperature. The results of these experiments are consistent with a thermonuclear neutron source.« less

  15. End point control of an actinide precipitation reactor

    SciTech Connect

    Muske, K.R.; Palmer, M.J.

    1997-10-01

    The actinide precipitation reactors in the nuclear materials processing facility at Los Alamos National Laboratory are used to remove actinides and other heavy metals from the effluent streams generated during the purification of plutonium. These effluent streams consist of hydrochloric acid solutions, ranging from one to five molar in concentration, in which actinides and other metals are dissolved. The actinides present are plutonium and americium. Typical actinide loadings range from one to five grams per liter. The most prevalent heavy metals are iron, chromium, and nickel that are due to stainless steel. Removal of these metals from solution is accomplished by hydroxide precipitation during the neutralization of the effluent. An end point control algorithm for the semi-batch actinide precipitation reactors at Los Alamos National Laboratory is described. The algorithm is based on an equilibrium solubility model of the chemical species in solution. This model is used to predict the amount of base hydroxide necessary to reach the end point of the actinide precipitation reaction. The model parameters are updated by on-line pH measurements.

  16. Wideband Heterodyne QWIP Receiver Development for Thermonuclear Fusion Measurements

    SciTech Connect

    Bennett, C.A.; Buchanan, M.; Hutchinson, D.P.; Liu, H.C.; Richards, R.K.; Simpson, M.L.

    1998-11-01

    Oak Ridge National Laboratory (ORNL) has been developing heterodyne receivers for plasma diagnostic applications for over 20 years. One area of this work has been the development of a diagnostic system for the measurement of the energy of alpha particles created in a thermonuclear fusion reactor. These particles originate with an energy of 3.5 MeV and cool to the thermal energy of the plasma (around 15 keV) after several seconds. To measure the velocity distribution of these alpha particles, a Thomson scattering diagnostic is under development based on a high power CO{sub 2} laser at 10 microns with a heterodyne receiver. The Doppler shift generated by Thomson scattering of the alpha particles requires a wideband heterodyne receiver (greater than 10 GHz). Because Mercury-Cadimum-Telluride (MCT) detectors are limited to a bandwidth of approximately 2 GHz, a Quantum Well Infrared Photodetector (QWIP) detector was obtained from the National Research Council of Canada (NRC) and evaluated for its heterodyne performance using the heterodyne testing facility developed at ORNL.

  17. Plasma transport control and self-sustaining fusion reactor

    NASA Astrophysics Data System (ADS)

    Ono, M.; Bell, R.; Choe, W.; Chang, C. S.; Forest, C. B.; Goldston, R.; Hwang, Y. S.; Jardin, S. C.; Kaita, R.; Kaye, S.; Kessel, C. E.; Kugel, H.; LeBlanc, B.; Manickam, J.; Menard, J. E.; Munsat, T.; Okabayashi, M.; Peng, M.; Sesnic, S.; Tighe, W.

    1997-05-01

    The possibility of a high-performance/low-cost fusion reactor concept which can simultaneously satisfy (1) high beta, (2) high bootstrap fractio (self-sustaining) and (3) high confinement is discussed. In CDX-U, a tokamak configuration was created and sustained solely by internally generated bootstrap currents, in which a 'seed' current is created through a nonclassical current diffusion process. Recent theoretical studies of MHD stability limits in spherical tori [e.g. the National Spherical Torus Experiment (NSTX)] produced a promising regime with stable beta of 45% and bootstrap current fraction of $\\ge$ 99%control the pressure profile. It is suggested that the most efficient approach for pressure profile control is through the creation of transport barriers (localized regions of low plasma transport) in the plasma. As a tool for creating the core transport barrier, poloidal-sheared-flow generation by ion Bernstein waves (IBW) near the wave absorption region appears to be promising. In PBX-M, application of IBW power produced a high-quality internal transport barrier where the ion energy and particle transport became neoclassical in the barrier region. The observation is consistent with the IBW-induced-poloidal-sheared-flow model. An experiment is planned on TFTR to demonstrate this concept with D - T reactor-grade plasmas. For edge transport control, a method based on electron ripple injection (ERI), driven by electron cyclotron heating (ECH), is being developed on CDX-U. It is estimated that both the IBW and ERI methods can create a transport barrier in reactor-grade plasmas (e.g. ITER) with a relatively small amount of power $(\\approx 10 MW \\ll P_{fusion})$Control rod system useable for fuel handling in a gas-cooled nuclear reactor

    DOEpatents

    Spurrier, Francis R.

    1976-11-30

    A control rod and its associated drive are used to elevate a complete stack of fuel blocks to a position above the core of a gas-cooled nuclear reactor. A fuel-handling machine grasps the control rod and the drive is unlatched from the rod. The stack and rod are transferred out of the reactor, or to a new location in the reactor, by the fuel-handling machine.

  18. Power control of SAFE reactor using fuzzy logic

    NASA Astrophysics Data System (ADS)

    Irvine, Claude

    2002-01-01

    Controlling the 100 kW SAFE (Safe Affordable Fission Engine) reactor consists of design and implementation of a fuzzy logic process control system to regulate dynamic variables related to nuclear system power. The first phase of development concentrates primarily on system power startup and regulation, maintaining core temperature equilibrium, and power profile matching. This paper discusses the experimental work performed in those areas. Nuclear core power from the fuel elements is simulated using resistive heating elements while heat rejection is processed by a series of heat pipes. Both axial and radial nuclear power distributions are determined from neuronic modeling codes. The axial temperature profile of the simulated core is matched to the nuclear power profile by varying the resistance of the heating elements. The SAFE model establishes radial temperature profile equivalence by establishing 32 control zones as the nodal coordinates. Control features also allow for slow warm up, since complete shutoff can occur in the heat pipes if heat-source temperatures drop/rise below a certain minimum value, depending on the specific fluid and gas combination in the heat pipe. The entire system is expected to be self-adaptive, i.e., capable of responding to long-range changes in the space environment. Particular attention in the development of the fuzzy logic algorithm shall ensure that the system process remains at set point, virtually eliminating overshoot on start-up and during in-process disturbances. The controller design will withstand harsh environments and applications where it might come in contact with water, corrosive chemicals, radiation fields, etc. .

  19. Understanding Neutron Stars using Thermonuclear X-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, S.

    2007-01-01

    Studies of thermonuclear X-ray bursts can be very useful to constrain the spin rate, mass and radius of a neutron star = EOS model of high density cold matter in the neutron star cores. Extensive observation and analysis of the data from the rising portions of the bursts = modeling of burst oscillations and thermonuclear flame spreading. Theoretical study of thermonuclear flame spreading on the rapidly spinning neutron stars should be done considering all the main physical effects (including magnetic field, nuclear energy generation, Coriolis effect, strong gravity, etc.).

  1. Neutron Stars and Thermonuclear X-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, Sudip

    2007-01-01

    Studies of thermonuclear X-ray bursts can be very useful to constrain the spin rate, mass and radius of a neutron star approaching EOS model of high density cold matter in the neutron star cores. +k Extensive observation and analysis of the data from the rising portions of the bursts - modeling of burst oscillations and thermonuclear flame spreading. +k Theoretical study of thermonuclear flame spreading on the rapidly spinning neutron stars should be done considering all the main physical effects (including magnetic field, nuclear energy generation, Coriolis effect, strong gravity, etc.).

  2. Computer simulation of magnetization-controlled shunt reactors for calculating electromagnetic transients in power systems

    SciTech Connect

    Karpov, A. S.

    2013-01-15

    A computer procedure for simulating magnetization-controlled dc shunt reactors is described, which enables the electromagnetic transients in electric power systems to be calculated. It is shown that, by taking technically simple measures in the control system, one can obtain high-speed reactors sufficient for many purposes, and dispense with the use of high-power devices for compensating higher harmonic components.

  3. Validation of neutron flux redistribution factors in JSI TRIGA reactor due to control rod movements.

    PubMed

    Kaiba, Tanja; Žerovnik, Gašper; Jazbec, Anže; Štancar, Žiga; Barbot, Loïc; Fourmentel, Damien; Snoj, Luka

    2015-10-01

    For efficient utilization of research reactors, such as TRIGA Mark II reactor in Ljubljana, it is important to know neutron flux distribution in the reactor as accurately as possible. The focus of this study is on the neutron flux redistributions due to control rod movements. For analyzing neutron flux redistributions, Monte Carlo calculations of fission rate distributions with the JSI TRIGA reactor model at different control rod configurations have been performed. Sensitivity of the detector response due to control rod movement have been studied. Optimal radial and axial positions of the detector have been determined. Measurements of the axial neutron flux distribution using the CEA manufactured fission chambers have been performed. The experiments at different control rod positions were conducted and compared with the MCNP calculations for a fixed detector axial position. In the future, simultaneous on-line measurements with multiple fission chambers will be performed inside the reactor core for a more accurate on-line power monitoring system. PMID:26141293

  4. Bayesian Estimation of Thermonuclear Reaction Rates

    NASA Astrophysics Data System (ADS)

    Iliadis, C.; Anderson, K. S.; Coc, A.; Timmes, F. X.; Starrfield, S.

    2016-11-01

    The problem of estimating non-resonant astrophysical S-factors and thermonuclear reaction rates, based on measured nuclear cross sections, is of major interest for nuclear energy generation, neutrino physics, and element synthesis. Many different methods have been applied to this problem in the past, almost all of them based on traditional statistics. Bayesian methods, on the other hand, are now in widespread use in the physical sciences. In astronomy, for example, Bayesian statistics is applied to the observation of extrasolar planets, gravitational waves, and Type Ia supernovae. However, nuclear physics, in particular, has been slow to adopt Bayesian methods. We present astrophysical S-factors and reaction rates based on Bayesian statistics. We develop a framework that incorporates robust parameter estimation, systematic effects, and non-Gaussian uncertainties in a consistent manner. The method is applied to the reactions d(p,γ)3He, 3He(3He,2p)4He, and 3He(α,γ)7Be, important for deuterium burning, solar neutrinos, and Big Bang nucleosynthesis.

  5. Microfluidic Reactors for the Controlled Synthesis of Nanoparticles

    NASA Astrophysics Data System (ADS)

    Erdem, Emine Yegan

    Nanoparticles have attracted a lot of attention in the past few decades due to their unique, size-dependent properties. In order to use these nanoparticles in devices or sensors effectively, it is important to maintain uniform properties throughout the system; therefore nanoparticles need to have uniform sizes -- or monodisperse. In order to achieve monodispersity, an extreme control over the reaction conditions is required during their synthesis. These reaction conditions such as temperature, concentration of reagents, residence times, etc. affect the structure of nanoparticles dramatically; therefore when the conditions vary locally in the reaction vessel, different sized nanoparticles form, causing polydispersity. In widely-used batch wise synthesis techniques, large sized reaction vessels are used to mix and heat reagents. In these types of systems, it is very hard to avoid thermal gradients and to achieve rapid mixing times as well as to control residence times. Also it is not possible to make rapid changes in the reaction parameters during the synthesis. The other drawback of conventional methods is that it is not possible to separate the nucleation of nanoparticles from their growth; this leads to combined nucleation and growth and subsequently results in polydisperse size distributions. Microfluidics is an alternative method by which the limitations of conventional techniques can be addressed. Due to the small size, it is possible to control temperature and concentration of reagents precisely as well as to make rapid changes in mixing ratios of reagents or temperature of the reaction zones. There have been several microfluidic reactors -- (microreactors) in literature that were designed to improve the size distribution of nanoparticles. In this work, two novel microfluidic systems were developed for achieving controlled synthesis of nanoparticles. The first microreactor was made out of a chemically robust polymer, polyurethane, and it was used for low

  6. Demonstration of thermonuclear conditions in magnetized liner inertial fusion experiments

    SciTech Connect

    Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Hahn, Kelly D.; Hansen, Stephanie B.; Knapp, Patrick F.; Schmit, Paul F.; Ruiz, Carlos L.; Sinars, Daniel Brian; Harding, Eric C.; Jennings, Christopher A.; Awe, Thomas James; Geissel, Matthias; Rovang, Dean C.; Smith, Ian C.; Chandler, Gordon A.; Cooper, Gary Wayne; Cuneo, Michael Edward; Harvey-Thompson, Adam James; Herrmann, Mark C.; Mark Harry Hess; Lamppa, Derek C.; Martin, Matthew R.; McBride, Ryan D.; Peterson, Kyle J.; Porter, John L.; Rochau, Gregory A.; Savage, Mark E.; Schroen, Diana G.; Stygar, William A.; Vesey, Roger Alan

    2015-04-29

    In this study, the magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas17, 056303 (2010)] utilizes a magnetic field and laser heating to relax the pressure requirements of inertial confinement fusion. The first experiments to test the concept [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] were conducted utilizing the 19 MA, 100 ns Z machine, the 2.5 kJ, 1 TW Z Beamlet laser, and the 10 T Applied B-field on Z system. Despite an estimated implosion velocity of only 70 km/s in these experiments, electron and ion temperatures at stagnation were as high as 3 keV, and thermonuclear deuterium-deuterium neutron yields up to 2 × 1012 have been produced. X-ray emission from the fuel at stagnation had widths ranging from 50 to 110 μm over a roughly 80% of the axial extent of the target (6–8 mm) and lasted approximately 2 ns. X-ray yields from these experiments are consistent with a stagnation density of the hot fuel equal to 0.2–0.4 g/cm3. In these experiments, up to 5 ×1010 secondary deuterium-tritium neutrons were produced. Given that the areal density of the plasma was approximately 1–2 mg/cm2, this indicates the stagnation plasma was significantly magnetized, which is consistent with the anisotropy observed in the deuterium-tritium neutron spectra. Control experiments where the laser and/or magnetic field were not utilized failed to produce stagnation temperatures greater than 1 keV and primary deuterium-deuterium yields greater than 1010. An additional control experiment where the fuel contained a sufficient dopant fraction to substantially increase radiative losses also failed to produce a relevant stagnation temperature. The results of these experiments are consistent with a thermonuclear neutron source.

  7. Demonstration of thermonuclear conditions in magnetized liner inertial fusion experiments

    SciTech Connect

    Gomez, M. R.; Slutz, S. A.; Sefkow, A. B.; Hahn, K. D.; Hansen, S. B.; Knapp, P. F.; Schmit, P. F.; Ruiz, C. L.; Sinars, D. B.; Harding, E. C.; Jennings, C. A.; Awe, T. J.; Geissel, M.; Rovang, D. C.; Smith, I. C.; Chandler, G. A.; Cooper, G. W.; Cuneo, M. E.; Harvey-Thompson, A. J.; Hess, M. H.; and others

    2015-05-15

    The magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)] utilizes a magnetic field and laser heating to relax the pressure requirements of inertial confinement fusion. The first experiments to test the concept [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] were conducted utilizing the 19 MA, 100 ns Z machine, the 2.5 kJ, 1 TW Z Beamlet laser, and the 10 T Applied B-field on Z system. Despite an estimated implosion velocity of only 70 km/s in these experiments, electron and ion temperatures at stagnation were as high as 3 keV, and thermonuclear deuterium-deuterium neutron yields up to 2 × 10{sup 12} have been produced. X-ray emission from the fuel at stagnation had widths ranging from 50 to 110 μm over a roughly 80% of the axial extent of the target (6–8 mm) and lasted approximately 2 ns. X-ray yields from these experiments are consistent with a stagnation density of the hot fuel equal to 0.2–0.4 g/cm{sup 3}. In these experiments, up to 5 × 10{sup 10} secondary deuterium-tritium neutrons were produced. Given that the areal density of the plasma was approximately 1–2 mg/cm{sup 2}, this indicates the stagnation plasma was significantly magnetized, which is consistent with the anisotropy observed in the deuterium-tritium neutron spectra. Control experiments where the laser and/or magnetic field were not utilized failed to produce stagnation temperatures greater than 1 keV and primary deuterium-deuterium yields greater than 10{sup 10}. An additional control experiment where the fuel contained a sufficient dopant fraction to substantially increase radiative losses also failed to produce a relevant stagnation temperature. The results of these experiments are consistent with a thermonuclear neutron source.

  8. 65. ARAII. Interior view of SL1 reactor building control piping ...

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

    65. ARA-II. Interior view of SL-1 reactor building control piping for water purification system. On operating floor of building. March 21, 1958. Ineel photo no. 58-1360. Photographer: Jack L. Anderson. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

  9. 10 CFR 50.44 - Combustible gas control for nuclear power reactors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Combustible gas control for nuclear power reactors. 50.44 Section 50.44 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION... for nuclear power reactors. (a) Definitions—(1) Inerted atmosphere means a containment atmosphere...

  10. 10 CFR 50.44 - Combustible gas control for nuclear power reactors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Combustible gas control for nuclear power reactors. 50.44 Section 50.44 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION... for nuclear power reactors. (a) Definitions—(1) Inerted atmosphere means a containment atmosphere...

  11. 10 CFR 50.44 - Combustible gas control for nuclear power reactors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Combustible gas control for nuclear power reactors. 50.44 Section 50.44 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION... for nuclear power reactors. (a) Definitions—(1) Inerted atmosphere means a containment atmosphere...

  12. How an 8 path chordal ultrasonic flowmeter solves steam generator and reactor water level control problems

    SciTech Connect

    Estrada, H.; Hauser, E.

    2006-07-01

    The application of a chordal ultrasonic transit time flowmeter to reactor and steam generator water level control is described. Analyses show that the extremely high turndown of the ultrasonic instrument, when coupled with a linear steam demand signal, leads to water level control system performance far superior to that achieved with conventional flow instruments, particularly at very low power. The proposed control system is readily justified by reduced startup times, avoidance of reactor trips (scrams), and reduced feedwater pumping power requirements. (authors)

  13. Enhanced situation awareness and decision making for an intelligent reconfigurable reactor power controller

    SciTech Connect

    Kenney, S.J.; Edwards, R.M.

    1996-07-01

    A Learning Automata based intelligent reconfigurable controller has been adapted for use as a reactor power controller to achieve improved reactor temperature performance. The intelligent reconfigurable controller is capable of enforcing either a classical or an optimal reactor power controller based on control performance feedback. Four control performance evaluation measures: dynamically estimated average quadratic temperature error, power, rod reactivity and rod reactivity rate were developed to provide feedback to the control decision component of the intelligent reconfigurable controller. Fuzzy Logic and Neural Network controllers have been studied for inclusion in the bank of controllers that form the intermediate level of an enhanced intelligent reconfigurable reactor power controller (IRRPC). The increased number of alternatives available to the supervisory level of the IRRPC requires enhanced situation awareness. Additional performance measures have been designed and a method for synthesizing them into a single indication of the overall performance of the currently enforced reactor power controller has been conceptualized. Modification of the reward/penalty scheme implemented in the existing IRRPC to increase the quality of the supervisory level decision process has been studied. The logogen model of human memory (Morton, 1969) and individual controller design information could be used to allocate reward to the most appropriate controller. Methods for allocating supervisory level attention were also studied with the goal of maximizing learning rate.

  14. Thermonuclear model for x-ray transients

    SciTech Connect

    Wallace, R.K.; Woosley, S.E.; Weaver, T.A.

    1982-01-01

    The thermonuclear evolution of a 1.41 M sub solar neutron star accreting both solar and metal-deficient mixtures of hydrogen, helium, and heavy elements at rates ranging from about 10/sup -11/ to 10/sup -10/ M sub solar per year is examined using a one-dimensional numerical model. The metal deficient compositions may result either from placement of the neutron star in a binary system with a Population II red giant or from gravitational settling of heavy ions in the accreted material. For such accretion rates and metallicities, hydrogen burning, mediated by the ..beta..-limited CNO cycle, is stable and leads to the accumulation of a thick helium layer with mass 10/sup 23/ to 10/sup 25/ g and temperature 0.7 less than or equal to T/sub 8/ less than or equal to 1.2. Helium ignition occurs under extremely degenerate circumstances and is catastrophically violent. In the lower t helium shells this runaway is propagated as a convective deflagration, for the thicker layers a detonation front is set up which steepens into a strong relativistic shock wave in the neutron star envelope. In all models greatly super-Eddington luminosities in the outer layers of the neutron star lead to a sustained epoch of radiatively driven mass loss. Observationally, such models may correspond to rapid x-ray transients. The hopeless prospect for constructing a one-dimensional model for ..gamma..-ray bursts without magnetic field confinement is discussed and uncertainties pointed out in the strong screening correction for helium burning reaction.

  15. Cryogenic thermonuclear fuel implosions on the National Ignition Facility

    SciTech Connect

    Glenzer, S. H.; Callahan, D. A.; MacKinnon, A. J.; Alger, E. T.; Berger, R. L.; Bernstein, L. A.; Bleuel, D. L.; Bradley, D. K.; Burkhart, S. C.; Burr, R.; Caggiano, J. A.; Castro, C.; Choate, C.; Clark, D. S.; Celliers, P.; Cerjan, C. J.; Collins, G. W.; Dewald, E. L.; DiNicola, P.; DiNicola, J. M.; and others

    2012-05-15

    The first inertial confinement fusion implosion experiments with equimolar deuterium-tritium thermonuclear fuel have been performed on the National Ignition Facility. These experiments use 0.17 mg of fuel with the potential for ignition and significant fusion yield conditions. The thermonuclear fuel has been fielded as a cryogenic layer on the inside of a spherical plastic capsule that is mounted in the center of a cylindrical gold hohlraum. Heating the hohlraum with 192 laser beams for a total laser energy of 1.6 MJ produces a soft x-ray field with 300 eV temperature. The ablation pressure produced by the radiation field compresses the initially 2.2-mm diameter capsule by a factor of 30 to a spherical dense fuel shell that surrounds a central hot-spot plasma of 50 {mu}m diameter. While an extensive set of x-ray and neutron diagnostics has been applied to characterize hot spot formation from the x-ray emission and 14.1 MeV deuterium-tritium primary fusion neutrons, thermonuclear fuel assembly is studied by measuring the down-scattered neutrons with energies in the range of 10 to 12 MeV. X-ray and neutron imaging of the compressed core and fuel indicate a fuel thickness of (14 {+-} 3) {mu}m, which combined with magnetic recoil spectrometer measurements of the fuel areal density of (1 {+-} 0.09) g cm{sup -2} result in fuel densities approaching 600 g cm{sup -3}. The fuel surrounds a hot-spot plasma with average ion temperatures of (3.5 {+-} 0.1) keV that is measured with neutron time of flight spectra. The hot-spot plasma produces a total fusion neutron yield of 10{sup 15} that is measured with the magnetic recoil spectrometer and nuclear activation diagnostics that indicate a 14.1 MeV yield of (7.5{+-}0.1) Multiplication-Sign 10{sup 14} which is 70% to 75% of the total fusion yield due to the high areal density. Gamma ray measurements provide the duration of nuclear activity of (170 {+-} 30) ps. These indirect-drive implosions result in the highest areal densities

  16. Cryogenic thermonuclear fuel implosions on the National Ignition Facilitya)

    NASA Astrophysics Data System (ADS)

    Glenzer, S. H.; Callahan, D. A.; MacKinnon, A. J.; Kline, J. L.; Grim, G.; Alger, E. T.; Berger, R. L.; Bernstein, L. A.; Betti, R.; Bleuel, D. L.; Boehly, T. R.; Bradley, D. K.; Burkhart, S. C.; Burr, R.; Caggiano, J. A.; Castro, C.; Casey, D. T.; Choate, C.; Clark, D. S.; Celliers, P.; Cerjan, C. J.; Collins, G. W.; Dewald, E. L.; DiNicola, P.; DiNicola, J. M.; Divol, L.; Dixit, S.; Döppner, T.; Dylla-Spears, R.; Dzenitis, E.; Eckart, M.; Erbert, G.; Farley, D.; Fair, J.; Fittinghoff, D.; Frank, M.; Frenje, L. J. A.; Friedrich, S.; Casey, D. T.; Gatu Johnson, M.; Gibson, C.; Giraldez, E.; Glebov, V.; Glenn, S.; Guler, N.; Haan, S. W.; Haid, B. J.; Hammel, B. A.; Hamza, A. V.; Haynam, C. A.; Heestand, G. M.; Hermann, M.; Hermann, H. W.; Hicks, D. G.; Hinkel, D. E.; Holder, J. P.; Holunda, D. M.; Horner, J. B.; Hsing, W. W.; Huang, H.; Izumi, N.; Jackson, M.; Jones, O. S.; Kalantar, D. H.; Kauffman, R.; Kilkenny, J. D.; Kirkwood, R. K.; Klingmann, J.; Kohut, T.; Knauer, J. P.; Koch, J. A.; Kozioziemki, B.; Kyrala, G. A.; Kritcher, A. L.; Kroll, J.; La Fortune, K.; Lagin, L.; Landen, O. L.; Larson, D. W.; LaTray, D.; Leeper, R. J.; Le Pape, S.; Lindl, J. D.; Lowe-Webb, R.; Ma, T.; McNaney, J.; MacPhee, A. G.; Malsbury, T. N.; Mapoles, E.; Marshall, C. D.; Meezan, N. B.; Merrill, F.; Michel, P.; Moody, J. D.; Moore, A. S.; Moran, M.; Moreno, K. A.; Munro, D. H.; Nathan, B. R.; Nikroo, A.; Olson, R. E.; Orth, C. D.; Pak, A. E.; Patel, P. K.; Parham, T.; Petrasso, R.; Ralph, J. E.; Rinderknecht, H.; Regan, S. P.; Robey, H. F.; Ross, J. S.; Rosen, M. D.; Sacks, R.; Salmonson, J. D.; Saunders, R.; Sater, J.; Sangster, C.; Schneider, M. B.; Séguin, F. H.; Shaw, M. J.; Spears, B. K.; Springer, P. T.; Stoeffl, W.; Suter, L. J.; Thomas, C. A.; Tommasini, R.; Town, R. P. J.; Walters, C.; Weaver, S.; Weber, S. V.; Wegner, P. J.; Whitman, P. K.; Widmann, K.; Widmayer, C. C.; Wilde, C. H.; Wilson, D. C.; Van Wonterghem, B.; MacGowan, B. J.; Atherton, L. J.; Edwards, M. J.; Moses, E. I.

    2012-05-01

    The first inertial confinement fusion implosion experiments with equimolar deuterium-tritium thermonuclear fuel have been performed on the National Ignition Facility. These experiments use 0.17 mg of fuel with the potential for ignition and significant fusion yield conditions. The thermonuclear fuel has been fielded as a cryogenic layer on the inside of a spherical plastic capsule that is mounted in the center of a cylindrical gold hohlraum. Heating the hohlraum with 192 laser beams for a total laser energy of 1.6 MJ produces a soft x-ray field with 300 eV temperature. The ablation pressure produced by the radiation field compresses the initially 2.2-mm diameter capsule by a factor of 30 to a spherical dense fuel shell that surrounds a central hot-spot plasma of 50 μm diameter. While an extensive set of x-ray and neutron diagnostics has been applied to characterize hot spot formation from the x-ray emission and 14.1 MeV deuterium-tritium primary fusion neutrons, thermonuclear fuel assembly is studied by measuring the down-scattered neutrons with energies in the range of 10 to 12 MeV. X-ray and neutron imaging of the compressed core and fuel indicate a fuel thickness of (14 ± 3) μm, which combined with magnetic recoil spectrometer measurements of the fuel areal density of (1 ± 0.09) g cm-2 result in fuel densities approaching 600 g cm-3. The fuel surrounds a hot-spot plasma with average ion temperatures of (3.5 ± 0.1) keV that is measured with neutron time of flight spectra. The hot-spot plasma produces a total fusion neutron yield of 1015 that is measured with the magnetic recoil spectrometer and nuclear activation diagnostics that indicate a 14.1 MeV yield of (7.5±0.1)×1014 which is 70% to 75% of the total fusion yield due to the high areal density. Gamma ray measurements provide the duration of nuclear activity of (170 ± 30) ps. These indirect-drive implosions result in the highest areal densities and neutron yields achieved on laser facilities to date

  17. Dual annular rotating [open quotes]windowed[close quotes] nuclear reflector reactor control system

    DOEpatents

    Jacox, M.G.; Drexler, R.L.; Hunt, R.N.M.; Lake, J.A.

    1994-03-29

    A nuclear reactor control system is provided in a nuclear reactor having a core operating in the fast neutron energy spectrum where criticality control is achieved by neutron leakage. The control system includes dual annular, rotatable reflector rings. There are two reflector rings: an inner reflector ring and an outer reflector ring. The reflectors are concentrically assembled, surround the reactor core, and each reflector ring includes a plurality of openings. The openings in each ring are capable of being aligned or non-aligned with each other. Independent driving means for each of the annular reflector rings is provided so that reactor criticality can be initiated and controlled by rotation of either reflector ring such that the extent of alignment of the openings in each ring controls the reflection of neutrons from the core. 4 figures.

  18. Reactor instrumentation and control design and performance simulation for SP-100

    NASA Technical Reports Server (NTRS)

    Meyer, R. A.; Alley, A. D.; Halfen, F. J.; Brynsvold, G. V.

    1987-01-01

    The SP-100 flight system will be launched with all primary and secondary lithium in the solid state. Once in orbit, the reactor will be brought critical and maintained at a low power level while the lithium is thawed out. Once the system is thawed out, the reactor power will be controlled to provide the energy source required by the power conversion system to meet the payload electrical power requirements. The Reactor Instrumentation and Control subsystem which includes the reactor control drives, instrumentation and the digital controller provides for the control of the nuclear subsystem to perform these operating maneuvers as well as providing for automatic shutdown and restart under certain off-normal conditions. The design and performance of this system are described.

  19. Comparison of Reactivity Control Systems for the Submersion Subcritical Safe Space (S and 4) Reactor

    SciTech Connect

    Schriener, Timothy M.; El-Genk, Mohamed S.

    2008-01-21

    This paper compares the effectiveness of two control mechanisms for the S and 4 reactor, namely: (a) rotating BeO drums with 120 deg. thin segments of enriched B{sub 4}C in the radial reflector; and (b) sliding windows in the radial reflector. Investigated are the effects of using these control mechanisms on the differential reactor control worth, power generation profiles, and spatial neutrons flux distributions is the S and 4 reactor. For both control mechanism, the radial reflector has the same dimensions and volume. Results show that the difference in reactor performance with the two control mechanisms is small. The sliding reflector configuration features slightly lower mass and power peaking, and relatively more even fission power profiles in the core. The differential control worth for the sliding reflector segments is almost constant compared to that using rotating control drums, potentially simplifying the reactor control operation. The presence of a strong neutron absorber in the rotating drums slightly decreases the amount of excess reactivity at BOL compared with the sliding reflector configuration. However, the higher rate of reactivity depletion in the S and 4 reactor with the latter may negate this advantage.

  20. Overview of environmental control aspects for the gas-cooled fast reactor

    SciTech Connect

    Nolan, A.M.

    1981-05-01

    Environmental control aspects relating to release of radionuclides have been analyzed for the Gas-Cooled Fast Reactor (GCFR). Information on environmental control systems was obtained for the most recent GCFR designs, and was used to evaluate the adequacy of these systems. The GCFR has been designed by the General Atomic Company as an alternative to other fast breeder reactor designs, such as the Liquid Metal Fast Breeder Reactor (LMFBR). The GCFR design includes mixed oxide fuel and helium coolant. The environmental impact of expected radionuclide releases from normal operation of the GCFR was evaluated using estimated collective dose equivalent commitments resulting from 1 year of plant operation. The results were compared to equivalent estimates for the Light Water Reactor (LWR) and High-Temperature Gas-Cooled Reactor (HTGR). A discussion of uncertainties in system performances, tritium production rates, and radiation quality factors for tritium is included.

  1. Reactor

    DOEpatents

    Evans, Robert M.

    1976-10-05

    1. A neutronic reactor having a moderator, coolant tubes traversing the moderator from an inlet end to an outlet end, bodies of material fissionable by neutrons of thermal energy disposed within the coolant tubes, and means for circulating water through said coolant tubes characterized by the improved construction wherein the coolant tubes are constructed of aluminum having an outer diameter of 1.729 inches and a wall thickness of 0.059 inch, and the means for circulating a liquid coolant through the tubes includes a source of water at a pressure of approximately 350 pounds per square inch connected to the inlet end of the tubes, and said construction including a pressure reducing orifice disposed at the inlet ends of the tubes reducing the pressure of the water by approximately 150 pounds per square inch.

  2. Cryogenic thermonuclear fuel implosions on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Glenzer, Siegfried

    2011-10-01

    The first inertial confinement fusion implosion experiments with cryogenic fuel layers have been fielded in preparation for ignition experiments on the National Ignition Facility. These experiments use mega joule laser energies that compress fusion capsules in indirect dive hohlraums to test initial hot spot formation and thermonuclear fuel assembly. Hydrogen-rich fuel (THD) provides a relatively low yield and diagnostics rich environment that allows us to measure the implosion core, neutron yield, temperatures and fuel areal density from a suite of x-ray and neutron diagnostics. These experiments have successfully demonstrated the control of the implosion shape using ignition grade cryogenic fuel layers, laser pulse shaping, and nonlinear plasma optics. The implosions show scaling of the DT fusion yield with ion temperature over more than one order of magnitude to a yield in excess of 1014 neutrons. Recent implosion performance improvements due to shock timing tuning have led to high Lawson confinement parameters. Additional tuning experiments are being performed with the goal to increase hot spot temperatures and to observe alpha particle heating with pure DT fuel. Prepared by LLNL under Contract DE-AC52-07NA27344.

  3. Sliding mode control of the space nuclear reactor system TOPAZ II

    SciTech Connect

    Shtessel, Y.B.; Wyant, F.J.

    1996-03-01

    The Automatic Control System (ACS) of the space nuclear reactor power system TOPAZ II that generates electricity from nuclear heat using in-core thermionic converters is considered. Sliding Mode Control Technique was applied to the reactor system controller design in order to provide the robust high accuracy following of a neutron (thermal) power reference profile in a start up regime and a payload electric power (current) reference profile following in an operation regime. Extensive simulations of the TOPAZ II reactor system with the designed sliding mode controllers showed improved accuracy and robustness of the reactor system performances in a start up regime and in an electric power supply regime as well. {copyright} {ital 1996 American Institute of Physics.}

  4. Analysis of a boron-carbide-drum-controlled critical reactor experiment

    NASA Technical Reports Server (NTRS)

    Mayo, W. T.

    1972-01-01

    In order to validate methods and cross sections used in the neutronic design of compact fast-spectrum reactors for generating electric power in space, an analysis of a boron-carbide-drum-controlled critical reactor was made. For this reactor the transport analysis gave generally satisfactory results. The calculated multiplication factor for the most detailed calculation was only 0.7-percent Delta k too high. Calculated reactivity worth of the control drums was $11.61 compared to measurements of $11.58 by the inverse kinetics methods and $11.98 by the inverse counting method. Calculated radial and axial power distributions were in good agreement with experiment.

  5. Turbulence may sink titanic reactor

    SciTech Connect

    Glanz, J.

    1996-12-06

    The $10 billion International Thermonuclear Experimental Reactor project is meant to show that fusion is a practical energy source, but a new set of calculations says ITER will fizzle. This article describes the expectations and the projections about its future, as well as the challenges recently mounted using new calculations. 3 figs.

  6. Do spherical tokamaks have a thermonuclear future?

    NASA Astrophysics Data System (ADS)

    Mirnov, S. V.

    2012-12-01

    the potential possibility of their use in thermonuclear research.

  7. NUCLEAR REACTOR

    DOEpatents

    Treshow, M.

    1961-09-01

    A boiling-water nuclear reactor is described wherein control is effected by varying the moderator-to-fuel ratio in the reactor core. This is accomplished by providing control tubes containing a liquid control moderator in the reactor core and providing means for varying the amount of control moderatcr within the control tubes.

  8. Movable-molybdenum-reflector reactivity experiments for control studies of compact space power reactor concepts

    NASA Technical Reports Server (NTRS)

    Fox, T. A.

    1973-01-01

    An experimental reflector reactivity study was made with a compact cylindrical reactor using a uranyl fluoride - water fuel solution. The reactor was axially unreflected and radially reflected with segments of molybdenum. The reflector segments were displaced incrementally in both the axial and radial dimensions, and the shutdown of each configuration was measured by using the pulsed-neutron source technique. The reactivity effects for axial and radial displacement of reflector segments are tabulated separately and compared. The experiments provide data for control-system studies of compact-space-power-reactor concepts.

  9. Prospects for Tokamak Fusion Reactors

    SciTech Connect

    Sheffield, J.; Galambos, J.

    1995-04-01

    This paper first reviews briefly the status and plans for research in magnetic fusion energy and discusses the prospects for the tokamak magnetic configuration to be the basis for a fusion power plant. Good progress has been made in achieving fusion reactor-level, deuterium-tritium (D-T) plasmas with the production of significant fusion power in the Joint European Torus (up to 2 MW) and the Tokamak Fusion Test Reactor (up to 10 MW) tokamaks. Advances on the technologies of heating, fueling, diagnostics, and materials supported these achievements. The successes have led to the initiation of the design phases of two tokamaks, the International Thermonuclear Experimental Reactor (ITER) and the US Toroidal Physics Experiment (TPX). ITER will demonstrate the controlled ignition and extended bum of D-T plasmas with steady state as an ultimate goal. ITER will further demonstrate technologies essential to a power plant in an integrated system and perform integrated testing of the high heat flux and nuclear components required to use fusion energy for practical purposes. TPX will complement ITER by testing advanced modes of steady-state plasma operation that, coupled with the developments in ITER, will lead to an optimized demonstration power plant.

  10. Control of the RF waveform at the chuck of an industrial oxide-etch reactor

    SciTech Connect

    BERRY,LEE; MAYNARD,HELEN; MILLER,PAUL A.; MOORE,TONY; PENDLEY,MICHAEL; RESTA,VICTORIA; SPARKS,DENNIS; YANG,QUINGYUN

    2000-05-04

    Radio frequency (rf) power is applied to the chuck of a high-density plasma reactor in order to extract ions and to control the energy of the ions used for the fabrication of microelectronic devices. In many cases, the temporal shape of the rf waveform largely determines the shape of the spectrum of those extracted ions, thereby strongly affecting feature evolution. Using auxiliary rf circuits the authors successfully made major changes to the rf potential waveform at the chuck of an Applied Materials 5300 HDP Omega reactor without affecting the normal functioning of the reactor's control systems. This work established the practical feasibility of techniques for modifying the ion energy distribution functions of industrial reactors.

  11. Real Time Optimizing Code for Stabilization and Control of Plasma Reactors

    1995-09-25

    LOOP4 is a flexible real-time control code that acquires signals (input variables) from an array of sensors, that computes therefrom the actual state of the reactor system, that compares the actual state to the desired state (a goal), and that commands changes to reactor controls (output, or manipulated variables) in order to minimize the difference between the actual state of the reactor and the desired state. The difference between actual and desired states is quantifiedmore » in terms of a distance metric in the space defined by the sensor measurements. The desired state of the reactor is specified in terms of target values of sensor readings that were obtained previously during development and optimization of a process engineer using conventional techniques.« less

  12. Operational performance of the three bean salad control algorithm on the ACRR (Annular Core Research Reactor)

    SciTech Connect

    Ball, R.M.; Madaras, J.J. . Space and Defense Systems); Trowbridge, F.R. Jr.; Talley, D.G.; Parma, E.J. Jr. )

    1991-01-01

    Experimental tests on the Annular Core Research Reactor have confirmed that the Three-Bean-Salad'' control algorithm based on the Pontryagin maximum principle can change the power of a nuclear reactor many decades with a very fast startup rate and minimal overshoot. The paper describes the results of simulations and operations up to 25 MW and 87 decades per minute. 3 refs., 4 figs., 1 tab.

  13. Reflected kinetics model for nuclear space reactor kinetics and control scoping calculations

    SciTech Connect

    Washington, K.E.

    1986-01-01

    Renewed interest in space nuclear applications has motivated the study of a specialized reactor kinetics model. Consideration of a kinetics model favorable for study of the feasibility of automatic control of these devices is warranted. The need to bridge this gap between reactor kinetics and automatic control in conjunction with the control drum design characteristic of next generation paper space reactors inspired the development of a new Reflected Kinetics (RK) model. An extension of the conventional point-kinetics (PK) model was done in order to explicitly correlate reactivity and the reflector/absorber control drums characteristic of space nuclear reactor designs. Open-loop computations and numerical comparison to analytic PK equations indicated that the RK model is a functional alternative to equivalent bare point kinetics in the analysis of moderate transients. Variations in the RK reflector-to-core transfer probabilities and coolant flow rate do indeed drive the transient differently than the lumped insertion of equivalent reactivity amounts in the core. These computations illustrated the potential importance of the utilization of variable coolant flow rate to aid control in space reactor systems limited by minimal drum reactivity worth. Additionally the Doppler reactivity shutdown mechanism was concluded to be the primarily reliable means of safety shutdown in such systems. The structure of the RK equations proved to be advantageous for integration of automatic control.

  14. METHOD OF CONTROLLING CORROSION IN A NEUTRONIC REACTOR

    DOEpatents

    Kidder, C.P.; Sloan, C.K.

    1959-10-01

    A method is described for reducing or removing corrosion and iron deposits on aluminum surfaces from coolant water comprising adding to the coolant alkali metal dichromate in a concentration of between 1.8 and 2.2 ppm, adjusting the pH to between 7.3 and 7.8 by adding CaCO/sub 3/ or other similar material, and adding a silicious material such as diatomaceous earth of a particle size of 5 to 15 microns to effect a suspension of between 2 and 300 ppm and circulating it through the reactor.

  15. Thermonuclear Fusion: An Energy Source for the Future

    ERIC Educational Resources Information Center

    Drummond, William E.

    1973-01-01

    Discusses current research in thermonuclear fusion with particular emphasis on the problem of confining hot plasma. Recent experiments indicate that magnetic bottles called tokamaks may achieve the necessary confinement times, and this break-through has given renewed optimism to the feasibility of commercial fusion power by the turn of the…

  16. Supervisory control design based on hybrid systems and fuzzy events detection. Application to an oxichlorination reactor.

    PubMed

    Altamiranda, Edmary; Torres, Horacio; Colina, Eliezer; Chacón, Edgar

    2002-10-01

    This paper presents a supervisory control scheme based on hybrid systems theory and fuzzy events detection. The fuzzy event detector is a linguistic model, which synthesizes complex relations between process variables and process events incorporating experts' knowledge about the process operation. This kind of detection allows the anticipation of appropriate control actions, which depend upon the selected membership functions used to characterize the process under scrutiny. The proposed supervisory control scheme was successfully implemented for an oxichlorination reactor in a vinyl monomer plant. This implementation has allowed improvement of reactor stability and reduction of raw material consumption. PMID:12398279

  17. Self-actuating and locking control for nuclear reactor

    DOEpatents

    Chung, Dong K.

    1982-01-01

    A self-actuating, self-locking flow cutoff valve particularly suited for use in a nuclear reactor of the type which utilizes a plurality of fluid support neutron absorber elements to provide for the safe shutdown of the reactor. The valve comprises a substantially vertical elongated housing and an aperture plate located in the housing for the flow of fluid therethrough, a substantially vertical elongated nozzle member located in the housing and affixed to the housing with an opening in the bottom for receiving fluid and apertures adjacent a top end for discharging fluid. The nozzle further includes two sealing means, one located above and the other below the apertures. Also located in the housing and having walls surrounding the nozzle is a flow cutoff sleeve having a fluid opening adjacent an upper end of the sleeve, the sleeve being moveable between an upper open position wherein the nozzle apertures are substantially unobstructed and a closed position wherein the sleeve and nozzle sealing surfaces are mated such that the flow of fluid through the apertures is obstructed. It is a particular feature of the present invention that the valve further includes a means for utilizing any increase in fluid pressure to maintain the cutoff sleeve in a closed position. It is another feature of the invention that there is provided a means for automatically closing the valve whenever the flow of fluid drops below a predetermined level.

  18. Electric-stepping-motor tests for a control-drum actuator of a nuclear reactor

    NASA Technical Reports Server (NTRS)

    Kieffer, A. W.

    1972-01-01

    Experimental tests were conducted on two stepping motors for application as reactor control-drum actuators. Various control-drum loads with frictional resistances ranging from approximately zero to 40 N-m and inertias ranging from zero to 0.424 kg-sq m were tested.

  19. Physics and Control Assessment of AN 850 Mw(e) - Leu-Candu Reactor.

    NASA Astrophysics Data System (ADS)

    Barbone, Michelangelo

    The physics and control assessment of an 850 MW(e) Low Enriched Uranium CANDU Pressurized Heavy Water (LEU -CANDU-PHW) reactor constitute the major objective of this thesis. The use of Low Enriched Uranium fuel in the present CANDU nuclear power generating stations is recognized as economically beneficial due to reduced fuelling costs. The LEU fuel cycle is also recognized as a stepping stone to transit from the present CANDU-PHW once-through natural Uranium cycle to advanced cycles such as those based on Plutonium recycle, once-through Th + U-235 cycle, Thorium with Uranium recycle and net U-235 feed, Thorium with Uranium recycle and Plutonium feed. However, although the use of Low Enriched Uranium in the present CANDU-PHW reactor has economic advantages, and it would act as a technical bridge between the present cycle and advanced cycles, technical problems in different areas of reactor physics and fuel management were anticipated. The present thesis research work adresses the areas of reactor physics, fuel management, and control (in particular, the spatial control of large CANDU-PHW reactors). The main conclusions that have been drawn following these studies are as follows: (1) The Low Enriched Uranium Cycle is feasible in a CANDU-PHW reactor of present design and provided that: (a) The enrichment is kept relatively low (that is, about 1% instead of 0.711%); (b) the number of bundles to be replaced at every refuelling operation is about one-half that of the natural Uranium fuel case; (c) The channels are refuelled in the same direction as the coolant. (2) The response of an LEU-CANDU-PHW reactor to reactivity perturbation such as single- and two-channel refuelling operation, shim transient, shutdown-start-up transient with enrichment levels of 0.9% and 1.2% is essentially very similar {provided that certain conditions in (1) are respected} to that of the natural uranium reactor core case without any reactor reoptimization. The general behaviour of the reactor

  20. Control rod calibration and reactivity effects at the IPEN/MB-01 reactor

    SciTech Connect

    Pinto, Letícia Negrão; Gonnelli, Eduardo; Santos, Adimir dos

    2014-11-11

    Researches that aim to improve the performance of neutron transport codes and quality of nuclear cross section databases are very important to increase the accuracy of simulations and the quality of the analysis and prediction of phenomena in the nuclear field. In this context, relevant experimental data such as reactivity worth measurements are needed. Control rods may be made of several neutron absorbing materials that are used to adjust the reactivity of the core. For the reactor operation, these experimental data are also extremely important: with them it is possible to estimate the reactivity worth by the movement of the control rod, understand the reactor response at each rod position and to operate the reactor safely. This work presents a temperature correction approach for the control rod calibration problem. It is shown the control rod calibration data of the IPEN/MB-01 reactor, the integral and differential reactivity curves and a theoretical analysis, performed by the MCNP-5 reactor physics code, developed and maintained by Los Alamos National Laboratory, using the ENDF/B-VII.0 nuclear data library.

  1. Control rod calibration and reactivity effects at the IPEN/MB-01 reactor

    NASA Astrophysics Data System (ADS)

    Pinto, Letícia Negrão; Gonnelli, Eduardo; dos Santos, Adimir

    2014-11-01

    Researches that aim to improve the performance of neutron transport codes and quality of nuclear cross section databases are very important to increase the accuracy of simulations and the quality of the analysis and prediction of phenomena in the nuclear field. In this context, relevant experimental data such as reactivity worth measurements are needed. Control rods may be made of several neutron absorbing materials that are used to adjust the reactivity of the core. For the reactor operation, these experimental data are also extremely important: with them it is possible to estimate the reactivity worth by the movement of the control rod, understand the reactor response at each rod position and to operate the reactor safely. This work presents a temperature correction approach for the control rod calibration problem. It is shown the control rod calibration data of the IPEN/MB-01 reactor, the integral and differential reactivity curves and a theoretical analysis, performed by the MCNP-5 reactor physics code, developed and maintained by Los Alamos National Laboratory, using the ENDF/B-VII.0 nuclear data library.

  2. Apparatus for controlling coolant level in a liquid-metal-cooled nuclear reactor

    DOEpatents

    Jones, Robert D.

    1978-01-01

    A liquid-metal-cooled fast-breeder reactor which has a thermal liner spaced inwardly of the pressure vessel and includes means for passing bypass coolant through the annulus between the thermal liner and the pressure vessel to insulate the pressure vessel from hot outlet coolant includes control ports in the thermal liner a short distance below the normal operating coolant level in the reactor and an overflow nozzle in the pressure vessel below the control ports connected to an overflow line including a portion at an elevation such that overflow coolant flow is established when the coolant level in the reactor is above the top of the coolant ports. When no makeup coolant is added, bypass flow is inwardly through the control ports and there is no overflow; when makeup coolant is being added, coolant flow through the overflow line will maintain the coolant level.

  3. Design of a PID Controller for a PCR Micro Reactor

    ERIC Educational Resources Information Center

    Dinca, M. P.; Gheorghe, M.; Galvin, P.

    2009-01-01

    Proportional-integral-derivative (PID) controllers are widely used in process control, and consequently they are described in most of the textbooks on automatic control. However, rather than presenting the overall design process, the examples given in such textbooks are intended to illuminate specific focused aspects of selection, tuning and…

  4. Research on pressure control of pressurizer in pressurized water reactor nuclear power plant

    NASA Astrophysics Data System (ADS)

    Dai, Ling; Yang, Xuhong; Liu, Gang; Ye, Jianhua; Qian, Hong; Xue, Yang

    2010-07-01

    Pressurizer is one of the most important components in the nuclear reactor system. Its function is to keep the pressure of the primary circuit. It can prevent shutdown of the system from the reactor accident under the normal transient state while keeping the setting value in the normal run-time. This paper is mainly research on the pressure system which is running in the Daya Bay Nuclear Power Plant. A conventional PID controller and a fuzzy controller are designed through analyzing the dynamic characteristics and calculating the transfer function. Then a fuzzy PID controller is designed by analyzing the results of two controllers. The fuzzy PID controller achieves the optimal control system finally.

  5. Reflected kinetics model for nuclear space reactor kinetics and control scoping calculations

    SciTech Connect

    Washington, K.E.

    1986-05-01

    The objective of this research is to develop a model that offers an alternative to the point kinetics (PK) modelling approach in the analysis of space reactor kinetics and control studies. Modelling effort will focus on the explicit treatment of control drums as reactivity input devices so that the transition to automatic control can be smoothly done. The proposed model is developed for the specific integration of automatic control and the solution of the servo mechanism problem. The integration of the kinetics model with an automatic controller will provide a useful tool for performing space reactor scoping studies for different designs and configurations. Such a tool should prove to be invaluable in the design phase of a space nuclear system from the point of view of kinetics and control limitations.

  6. Chemistry control and corrosion mitigation of heat transfer salts for the fluoride salt reactor (FHR)

    SciTech Connect

    Kelleher, B. C.; Sellers, S. R.; Anderson, M. H.; Sridharan, K.; Scheele, R. D.

    2012-07-01

    The Molten Salt Reactor Experiment (MSRE) was a prototype nuclear reactor which operated from 1965 to 1969 at Oak Ridge National Laboratory. The MSRE used liquid fluoride salts as a heat transfer fluid and solvent for fluoride based {sup 235}U and {sup 233}U fuel. Extensive research was performed in order to optimize the removal of oxide and metal impurities from the reactor's heat transfer salt, 2LiF-BeF{sub 2} (FLiBe). This was done by sparging a mixture of anhydrous hydrofluoric acid and hydrogen gas through the FLiBe at elevated temperatures. The hydrofluoric acid reacted with oxides and hydroxides, fluorinating them while simultaneously releasing water vapor. Metal impurities such as iron and chromium were reduced by hydrogen gas and filtered out of the salt. By removing these impurities, the corrosion of reactor components was minimized. The Univ. of Wisconsin - Madison is currently researching a new chemical purification process for fluoride salts that make use of a less dangerous cleaning gas, nitrogen trifluoride. Nitrogen trifluoride has been predicted as a superior fluorinating agent for fluoride salts. These purified salts will subsequently be used for static and loop corrosion tests on a variety of reactor materials to ensure materials compatibility for the new FHR designs. Demonstration of chemistry control methodologies along with potential reduction in corrosion is essential for the use of a fluoride salts in a next generator nuclear reactor system. (authors)

  7. Reactor control system upgrade for the McClellan Nuclear Radiation Center Sacramento, CA.

    SciTech Connect

    Power, M. A.

    1999-03-10

    Argonne National Laboratory is currently developing a new reactor control system for the McClellan Nuclear Radiation Facility. This new control system not only provides the same functionality as the existing control system in terms of graphic displays of reactor process variables, data archival capability, and manual, automatic, pulse and square-wave modes of operation, but adds to the functionality of the previous control system by incorporating signal processing algorithms for the validation of sensors and automatic calibration and verification of control rod worth curves. With the inclusion of these automated features, the intent of this control system is not to replace the operator but to make the process of controlling the reactor easier and safer for the operator. For instance, an automatic control rod calibration method reduces the amount of time to calibrate control rods from days to minutes, increasing overall reactor utilization. The control rod calibration curve, determined using the automatic calibration system, can be validated anytime after the calibration, as long as the reactor power is between 50W and 500W. This is done by banking all of the rods simultaneously and comparing the tabulated rod worth curves with a reactivity computer estimate. As long as the deviation between the tabulated values and the reactivity estimate is within a prescribed error band, then the system is in calibration. In order to minimize the amount of information displayed, only the essential flux-related data are displayed in graphical format on the control screen. Information from the sensor validation methods is communicated to the operators via messages, which appear in a message window. The messages inform the operators that the actual process variables do not correlate within the allowed uncertainty in the reactor system. These warnings, however, cannot cause the reactor to shutdown automatically. The reactor operator has the ultimate responsibility of using this

  8. Iodine Volatility and pH Control in the AP-600 Reactor

    SciTech Connect

    Beahm, E.C.; Weber, C.F.

    1998-10-01

    Two design-basis accidents for the AP-600 reactor are formulated and evaluate~ in which significant bypass of the principal pH control system occurs. Some iodine released from the reactor primary system is retained in the Incontainment Refaeling Water Storage Tank (IRWST) water, never entering the containment where trisodium phosphate produces a high pH. Some of this iodine is volatilized and is transported into the reactor containment airspace. in the worst case, a small fraction is released to the environment at design-basis leak rate, yielding a total cumulative iodine release at 30 days of 0.0352 mol (0.023% of core iodine inventory) due to the iodine volatilization bypassing the pH control system. No fission product removal in the containment atmosphere (i.e., natural deposition sprays) is considered.

  9. Neutron economic reactivity control system for light water reactors

    DOEpatents

    Luce, Robert G.; McCoy, Daniel F.; Merriman, Floyd C.; Gregurech, Steve

    1989-01-01

    A neutron reactivity control system for a LWBR incorporating a stationary seed-blanket core arrangement. The core arrangement includes a plurality of contiguous hexagonal shaped regions. Each region has a central and a peripheral blanket area juxapositioned an annular seed area. The blanket areas contain thoria fuel rods while the annular seed area includes seed fuel rods and movable thoria shim control rods.

  10. REACTOR ANALYSIS AND VIRTUAL CONTROL ENVIRONMENT (RAVEN) FY12 REPORT

    SciTech Connect

    Cristian Rabiti; Andrea Alfonsi; Joshua Cogliati; Diego Mandelli; Robert Kinoshita

    2012-09-01

    RAVEN is a complex software tool that will have tasks spanning from being the RELAP-7 user interface, to using RELAP-7 to perform Risk Informed Safety Characterization (RISMC), and to controlling RELAP-7 calculation execution. The goal of this document is to: 1. Highlight the functional requirements of the different tasks of RAVEN 2. Identify shared functions that could be aggregate in modules so to obtain a minimal software redundancy and maximize software utilization. RAVEN is in fact a software framework that will allow exploiting the following functionalities: • Derive and actuate the control logic required to: o Simulate the plant control system o Simulate the operator (procedure guided) actions o Perform Monte Carlo sampling of random distributed events o Perform event three based analysis • Provide a GUI to: o Input a plant description to RELAP-7 (component, control variable, control parameters) o Concurrent monitoring of Control Parameters o Concurrent alteration of control parameters • Provide Post Processing data mining capability based on o Dimensionality reduction o Cardinality reduction In this document it will be shown how an appropriate mathematical formulation of the control logic and probabilistic analysis leads to have most of the software infrastructure leveraged between the two main tasks. Further, this document will go through the development accomplished this year, including simulation results, and priorities for the next years development

  11. CONTROL ROD DRIVE MECHANISM FOR A NUCLEAR REACTOR

    DOEpatents

    Hawke, B.C.; Liederbach, F.J.; Lones, W.

    1963-05-14

    A lead-screw-type control rod drive featuring an electric motor and a fluid motor arranged to provide a selectably alternative driving means is described. The electric motor serves to drive the control rod slowly during normal operation, while the fluid motor, assisted by an automatic declutching of the electric motor, affords high-speed rod insertion during a scram. (AEC)

  12. On thermonuclear ignition criterion at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Cheng, Baolian; Kwan, Thomas J. T.; Wang, Yi-Ming; Batha, Steven H.

    2014-10-01

    Sustained thermonuclear fusion at the National Ignition Facility remains elusive. Although recent experiments approached or exceeded the anticipated ignition thresholds, the nuclear performance of the laser-driven capsules was well below predictions in terms of energy and neutron production. Such discrepancies between expectations and reality motivate a reassessment of the physics of ignition. We have developed a predictive analytical model from fundamental physics principles. Based on the model, we obtained a general thermonuclear ignition criterion in terms of the areal density and temperature of the hot fuel. This newly derived ignition threshold and its alternative forms explicitly show the minimum requirements of the hot fuel pressure, mass, areal density, and burn fraction for achieving ignition. Comparison of our criterion with existing theories, simulations, and the experimental data shows that our ignition threshold is more stringent than those in the existing literature and that our results are consistent with the experiments.

  13. Thermonuclear Burning as a Probe of Neutron Star

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod

    2008-01-01

    Thermonuclear fusion is a fundamental process taking place in the matter transferred onto neutron stars in accreting binary systems. The heat deposited by nuclear reactions becomes readily visible in the X-ray band when the burning is either unstable or marginally stable, and results in the rich phenomenology of X-ray bursts, superbursts, and mHz quasiperiodic oscillations. Fast X-ray timing observations with NASA's Rossi X-ray Timing Explorer (RXTE) over the past decade have revealed a wealth of new phenomena associated with thermonuclear burning on neutron stars, including the discovery of nuclear powered pulsations during X-ray bursts and superbursts. I will briefly review our current observational and theoretical understanding of these new phenomena, with an emphasis on recent findings, and discuss what they are telling us about the structure of neutron stars.

  14. Sonoluminescence, shock waves, and micro-thermonuclear fusion

    SciTech Connect

    Moss, W.C.; Clarke, D.B.; White, J.W.; Young, D.A.

    1995-08-01

    We have performed numerical hydrodynamic simulations of the growth and collapse of a sonoluminescing bubble in a liquid. Our calculations show that spherically converging shock waves are generated during the collapse of the bubble. The combination of the shock waves and a realistic equation of state for the gas in the bubble provides an explanation for the measured picosecond optical pulse widths and indicates that the temperatures near the center of the bubble may exceed 3O eV. This leads naturally to speculation about obtaining micro-thermonuclear fusion in a bubble filled with deuterium (D{sub 2}) gas. Consequently, we performed numerical simulations of the collapse of a D{sub 2} bubble in D{sub 2}0. A pressure spike added to the periodic driving amplitude creates temperatures that may be sufficient to generate a very small, but measurable number of thermonuclear D-D fusion reactions in the bubble.

  15. Shock ignition of thermonuclear fuel with high areal density.

    PubMed

    Betti, R; Zhou, C D; Anderson, K S; Perkins, L J; Theobald, W; Solodov, A A

    2007-04-13

    A novel method by C. Zhou and R. Betti [Bull. Am. Phys. Soc. 50, 140 (2005)] to assemble and ignite thermonuclear fuel is presented. Massive cryogenic shells are first imploded by direct laser light with a low implosion velocity and on a low adiabat leading to fuel assemblies with large areal densities. The assembled fuel is ignited from a central hot spot heated by the collision of a spherically convergent ignitor shock and the return shock. The resulting fuel assembly features a hot-spot pressure greater than the surrounding dense fuel pressure. Such a nonisobaric assembly requires a lower energy threshold for ignition than the conventional isobaric one. The ignitor shock can be launched by a spike in the laser power or by particle beams. The thermonuclear gain can be significantly larger than in conventional isobaric ignition for equal driver energy.

  16. On thermonuclear ignition criterion at the National Ignition Facility

    SciTech Connect

    Cheng, Baolian; Kwan, Thomas J. T.; Wang, Yi-Ming; Batha, Steven H.

    2014-10-15

    Sustained thermonuclear fusion at the National Ignition Facility remains elusive. Although recent experiments approached or exceeded the anticipated ignition thresholds, the nuclear performance of the laser-driven capsules was well below predictions in terms of energy and neutron production. Such discrepancies between expectations and reality motivate a reassessment of the physics of ignition. We have developed a predictive analytical model from fundamental physics principles. Based on the model, we obtained a general thermonuclear ignition criterion in terms of the areal density and temperature of the hot fuel. This newly derived ignition threshold and its alternative forms explicitly show the minimum requirements of the hot fuel pressure, mass, areal density, and burn fraction for achieving ignition. Comparison of our criterion with existing theories, simulations, and the experimental data shows that our ignition threshold is more stringent than those in the existing literature and that our results are consistent with the experiments.

  17. Validating real-time implementations of diagonal recurrent neural network and fuzzy logic controllers for nuclear reactor control

    SciTech Connect

    Ramaswamy, P.; Edwards, R.M.; Lee, K.Y.

    1994-12-31

    A diagonal recurrent neural network (DRNN) and a fuzzy logic controller (FLC) were designed for optimal temperature control. The DRNN and FLC utilize the response of a fifth-order, one delayed neutron group linear model to an optimal controller that was previously designed. In this paper, the results of testing a real-time implementation of the DRNN and FLC are presented. The method of testing that was utilized is called hardware in loop simulation (HILS). Here, a distributed simulation of a highly non-linear model of the reactor on a network of workstations is used in the final step of testing prior to experimentation on the reactor. Also, in this setup actual control hardware is used to validate the controller realizations.

  18. Optimization of boiling water reactor control rod patterns using linear search

    SciTech Connect

    Kiguchi, T.; Doi, K.; Fikuzaki, T.; Frogner, B.; Lin, C.; Long, A.B.

    1984-10-01

    A computer program for searching the optimal control rod pattern has been developed. The program is able to find a control rod pattern where the resulting power distribution is optimal in the sense that it is the closest to the desired power distribution, and it satisfies all operational constraints. The search procedure consists of iterative uses of two steps: sensitivity analyses of local power and thermal margins using a three-dimensional reactor simulator for a simplified prediction model; linear search for the optimal control rod pattern with the simplified model. The optimal control rod pattern is found along the direction where the performance index gradient is the steepest. This program has been verified to find the optimal control rod pattern through simulations using operational data from the Oyster Creek Reactor.

  19. Application of a fuzzy algorithm for pH control in a struvite crystallisation reactor.

    PubMed

    Chanona, J; Pastor, L; Borrás, L; Seco, A

    2006-01-01

    A struvite crystallisation process is highly dependent on pH. To achieve a high phosphorus recovery as struvite it is important to have an accurate control of pH in the reactor. The high non-linear response of pH value makes manual pH control difficult. Therefore, a software based on fuzzy logic control (FLC) has been developed to maintain the pH at a set value in a stirred reactor to crystallise struvite. The FLC developed has been based on Larsen's inference. In order to confirm the improvement of the pH stability using FLC software, different experiments have been carried out with manual control of the pH value, and with the FLC software. It has been demonstrated that using FLC software allows a precise control of pH with high stability, optimises the process, and minimises the operator intervention.

  20. Care of thermally injured victims of a thermonuclear explosion

    SciTech Connect

    Kaplan, J.Z.

    1983-04-29

    Nuclear war or accidental non-hostile nuclear explosion would obviously rank among the greatest disasters to affect mankind. In addition to massive numbers of casualties, depending on the circumstances, our ability to care for these casualties might also be affected. Despite the predictions of doomsday soothsayers, nothing is accomplished by burying one's head in the sand. Therefore, we must give consideration to how victims of a thermo-nuclear explosion would be cared for.

  1. Efficient GPU Accelerationfor Integrating Large Thermonuclear Networks in Astrophysics

    NASA Astrophysics Data System (ADS)

    Guidry, Mike

    2016-02-01

    We demonstrate the systematic implementation of recently-developed fast explicit kinetic integration algorithms on modern graphics processing unit (GPU) accelerators. We take as representative test cases Type Ia supernova explosions with extremely stiff thermonuclear reaction networks having 150-365 isotopic species and 1600-4400 reactions, assumed coupled to hydrodynamics using operator splitting. In such examples we demonstrate the capability to integrate independent thermonuclear networks from ~250-500 hydro zones (assumed to be deployed on CPU cores) in parallel on a single GPU in the same wall clock time that standard implicit methods can integrate the network for a single zone. This two or more orders of magnitude increase in efficiency for solving systems of realistic thermonuclear networks coupled to fluid dynamics implies that important coupled, multiphysics problems in various scientific and technical disciplines that were intractable, or could be simulated only with highly schematic kinetic networks, are now computationally feasible. As examples of such applications I will discuss our ongoing deployment of these new methods for Type Ia supernova explosions in astrophysics and for simulation of the complex atmospheric chemistry entering into weather and climate problems.

  2. PBF Reactor Building (PER620) as seen from control room window ...

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

    PBF Reactor Building (PER-620) as seen from control room window in PER-619. Photographer stood just outside window. Note exposed communication cables on desert surface. Date: July 2004. INEEL negative no. HD-41-9-3 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

  3. APPARATUS FOR CONTROL OF A BOILING REACTOR RESPONSIVE TO STEAM DEMAND

    DOEpatents

    Treshow, M.

    1963-07-23

    A method of controlling a fuel-rod-in-tube-type boilingwater reactor having nozzles at the point of water entry into the tube is described. Water is pumped into the nozzles by an auxiliary pump operated by steam from an interstage position of the associated turbine, so that the pumping speed is responsive to turbine demand. (AEC)

  4. Design of a self-tuning regulator for temperature control of a polymerization reactor.

    PubMed

    Vasanthi, D; Pranavamoorthy, B; Pappa, N

    2012-01-01

    The temperature control of a polymerization reactor described by Chylla and Haase, a control engineering benchmark problem, is used to illustrate the potential of adaptive control design by employing a self-tuning regulator concept. In the benchmark scenario, the operation of the reactor must be guaranteed under various disturbing influences, e.g., changing ambient temperatures or impurity of the monomer. The conventional cascade control provides a robust operation, but often lacks in control performance concerning the required strict temperature tolerances. The self-tuning control concept presented in this contribution solves the problem. This design calculates a trajectory for the cooling jacket temperature in order to follow a predefined trajectory of the reactor temperature. The reaction heat and the heat transfer coefficient in the energy balance are estimated online by using an unscented Kalman filter (UKF). Two simple physically motivated relations are employed, which allow the non-delayed estimation of both quantities. Simulation results under model uncertainties show the effectiveness of the self-tuning control concept.

  5. Reduction of Switching Surge by Controlled Shunt Reactor Switching of Gas Circuit Breaker

    NASA Astrophysics Data System (ADS)

    Kohyama, Haruhiko; Ito, Hiroki; Asai, Jun; Hidaka, Mikio; Yonezawa, Takashi

    Controlled switching system (CSS) with a 204kV gas circuit breaker (GCB) demonstrates to reduce an inrush current and to eliminate re-ignitions in shunt reactor switching. Target closing and opening instants for controlled switching are determined by the electrical and mechanical characteristics of GCB. Idle time dependence of the operating time, which gives a sufficient impact on controlling accuracy, is evaluated and successfully compensated by synchronous switching controller (SSC). Field operation of CSS for a year shows an effective suppression of inrush current on closing and prevention of re-ignitions on opening of shunt reactor. The operations also proved that the CSS has a satisfactory performance for electro-magnetic disturbance imposed in practical field.

  6. Reactor Controllability of 3-Region-Core Molten Salt Reactor System - A Study on Load Following Capability

    SciTech Connect

    Takahisa Yamamoto; Koshi Mitachi; Masatoshi Nishio

    2006-07-01

    The Molten Salt Reactor (MSR) systems are liquid-fueled reactors that can be used for actinide burning, production of electricity, production of hydrogen, and production of fissile fuels (breeding). Thorium (Th) and uranium-233 ({sup 233}U) are fertile and fissile of the MSR systems, and dissolved in a high-temperature molten fluoride salt (fuel salt) with a very high boiling temperature (up to 1650 K), that is both the reactor nuclear fuel and the coolant. The MSR system is one of the six advanced reactor concepts identified by the Generation IV International Forum (GIF) as a candidate for cooperative development. In the MSR system, fuel salt flows through a fuel duct constructed around a reactor core and fuel channel of a graphite moderator accompanied by fission reaction and heat generation, and flows out to an external-loop system consisted of a heat exchanger and a circulation pump. Due to the motion of fuel salt, delayed neutron precursors that are one of the source of neutron production make to change their position between the fission reaction and neutron emission events and decay even occur in the external loop system. Hence the reactivity and effective delayed neutron precursor fraction of the MSR system are lower than those of solid fuel reactor systems such as Boiling Water Reactors (BWRs) and Pressurised Water Reactor (PWRs). Since all of the presently operating nuclear power reactors utilize solid fuel, little attention had been paid to the MSR analysis of the reactivity loss and reactor characteristics change caused by the fuel salt circulation. Sides et al. and Shimazu et al. developed MSR analytical models based on the point reactor kinetics model to consider the effect of fuel salt flow. Their models represented a reactor as having six zones for fuel salt and three zones for the graphite moderator. Since their models employed the point reactor kinetics model and the rough temperature approximation, their results were not sufficiently accurate to

  7. Analysis of dashpot performance for rotating control drums of a lithium cooled fast reactor concept

    NASA Technical Reports Server (NTRS)

    Wenzler, C. J.

    1972-01-01

    A dashpot was incorporated in the design of the drive train of the rotating control drum to prevent shock damage to the control drum and drive train at the termination of a scram action. A rotating vane dashpot using reactor coolant lithium as a damping fluid appears to be the best candidate of the various damping devices explored. A performance analysis, results and discussion of vane type dashpots are presented.

  8. Nonlinear versus Ordinary Adaptive Control of Continuous Stirred-Tank Reactor

    PubMed Central

    Vojtesek, Jiri; Dostal, Petr

    2015-01-01

    Unfortunately, the major group of the systems in industry has nonlinear behavior and control of such processes with conventional control approaches with fixed parameters causes problems and suboptimal or unstable control results. An adaptive control is one way to how we can cope with nonlinearity of the system. This contribution compares classic adaptive control and its modification with Wiener system. This configuration divides nonlinear controller into the dynamic linear part and the static nonlinear part. The dynamic linear part is constructed with the use of polynomial synthesis together with the pole-placement method and the spectral factorization. The static nonlinear part uses static analysis of the controlled plant for introducing the mathematical nonlinear description of the relation between the controlled output and the change of the control input. Proposed controller is tested by the simulations on the mathematical model of the continuous stirred-tank reactor with cooling in the jacket as a typical nonlinear system. PMID:26346878

  9. Status and problems of fusion reactor development.

    PubMed

    Schumacher, U

    2001-03-01

    Thermonuclear fusion of deuterium and tritium constitutes an enormous potential for a safe, environmentally compatible and sustainable energy supply. The fuel source is practically inexhaustible. Further, the safety prospects of a fusion reactor are quite favourable due to the inherently self-limiting fusion process, the limited radiologic toxicity and the passive cooling property. Among a small number of approaches, the concept of toroidal magnetic confinement of fusion plasmas has achieved most impressive scientific and technical progress towards energy release by thermonuclear burn of deuterium-tritium fuels. The status of thermonuclear fusion research activity world-wide is reviewed and present solutions to the complicated physical and technological problems are presented. These problems comprise plasma heating, confinement and exhaust of energy and particles, plasma stability, alpha particle heating, fusion reactor materials, reactor safety and environmental compatibility. The results and the high scientific level of this international research activity provide a sound basis for the realisation of the International Thermonuclear Experimental Reactor (ITER), whose goal is to demonstrate the scientific and technological feasibility of a fusion energy source for peaceful purposes.

  10. Fuel cycle facility control system for the Integral Fast Reactor Program

    SciTech Connect

    Benedict, R.W.; Tate, D.A.

    1993-09-01

    As part of the Integral Fast Reactor (IFR) Fuel Demonstration, a new distributed control system designed, implemented and installed. The Fuel processes are a combination of chemical and machining processes operated remotely. To meet this special requirement, the new control system provides complete sequential logic control motion and positioning control and continuous PID loop control. Also, a centralized computer system provides near-real time nuclear material tracking, product quality control data archiving and a centralized reporting function. The control system was configured to use programmable logic controllers, small logic controllers, personal computers with touch screens, engineering work stations and interconnecting networks. By following a structured software development method the operator interface was standardized. The system has been installed and is presently being tested for operations.

  11. Modeling a multivariable reactor and on-line model predictive control.

    PubMed

    Yu, D W; Yu, D L

    2005-10-01

    A nonlinear first principle model is developed for a laboratory-scaled multivariable chemical reactor rig in this paper and the on-line model predictive control (MPC) is implemented to the rig. The reactor has three variables-temperature, pH, and dissolved oxygen with nonlinear dynamics-and is therefore used as a pilot system for the biochemical industry. A nonlinear discrete-time model is derived for each of the three output variables and their model parameters are estimated from the real data using an adaptive optimization method. The developed model is used in a nonlinear MPC scheme. An accurate multistep-ahead prediction is obtained for MPC, where the extended Kalman filter is used to estimate system unknown states. The on-line control is implemented and a satisfactory tracking performance is achieved. The MPC is compared with three decentralized PID controllers and the advantage of the nonlinear MPC over the PID is clearly shown.

  12. Material Control and Accounting Design Considerations for High-Temperature Gas Reactors

    SciTech Connect

    Trond Bjornard; John Hockert

    2011-08-01

    The subject of this report is domestic safeguards and security by design (2SBD) for high-temperature gas reactors, focusing on material control and accountability (MC&A). The motivation for the report is to provide 2SBD support to the Next Generation Nuclear Plant (NGNP) project, which was launched by Congress in 2005. This introductory section will provide some background on the NGNP project and an overview of the 2SBD concept. The remaining chapters focus specifically on design aspects of the candidate high-temperature gas reactors (HTGRs) relevant to MC&A, Nuclear Regulatory Commission (NRC) requirements, and proposed MC&A approaches for the two major HTGR reactor types: pebble bed and prismatic. Of the prismatic type, two candidates are under consideration: (1) GA's GT-MHR (Gas Turbine-Modular Helium Reactor), and (2) the Modular High-Temperature Reactor (M-HTR), a derivative of Areva's Antares reactor. The future of the pebble-bed modular reactor (PBMR) for NGNP is uncertain, as the PBMR consortium partners (Westinghouse, PBMR [Pty] and The Shaw Group) were unable to agree on the path forward for NGNP during 2010. However, during the technology assessment of the conceptual design phase (Phase 1) of the NGNP project, AREVA provided design information and technology assessment of their pebble bed fueled plant design called the HTR-Module concept. AREVA does not intend to pursue this design for NGNP, preferring instead a modular reactor based on the prismatic Antares concept. Since MC&A relevant design information is available for both pebble concepts, the pebble-bed HTGRs considered in this report are: (1) Westinghouse PBMR; and (2) AREVA HTR-Module. The DOE Office of Nuclear Energy (DOE-NE) sponsors the Fuel Cycle Research and Development program (FCR&D), which contains an element specifically focused on the domestic (or state) aspects of SBD. This Material Protection, Control and Accountancy Technology (MPACT) program supports the present work summarized in

  13. Apparatus and method for closed-loop control of reactor power in minimum time

    DOEpatents

    Bernard, Jr., John A.

    1988-11-01

    Closed-loop control law for altering the power level of nuclear reactors in a safe manner and without overshoot and in minimum time. Apparatus is provided for moving a fast-acting control element such as a control rod or a control drum for altering the nuclear reactor power level. A computer computes at short time intervals either the function: .rho.=(.beta.-.rho.).omega.-.lambda..sub.e '.rho.-.SIGMA..beta..sub.i (.lambda..sub.i -.lambda..sub.e ')+l* .omega.+l* [.omega..sup.2 +.lambda..sub.e '.omega.] or the function: .rho.=(.beta.-.rho.).omega.-.lambda..sub.e .rho.-(.lambda..sub.e /.lambda..sub.e)(.beta.-.rho.)+l* .omega.+l* [.omega..sup.2 +.lambda..sub.e .omega.-(.lambda..sub.e /.lambda..sub.e).omega.] These functions each specify the rate of change of reactivity that is necessary to achieve a specified rate of change of reactor power. The direction and speed of motion of the control element is altered so as to provide the rate of reactivity change calculated using either or both of these functions thereby resulting in the attainment of a new power level without overshoot and in minimum time. These functions are computed at intervals of approximately 0.01-1.0 seconds depending on the specific application.

  14. Loop system with gas control of the power production in the MR reactor

    SciTech Connect

    Andreev, V.I.; Kolyadin, V.I.; Smirnov, A.I.; Yakovlev, V.V.

    1987-01-01

    An unsolved problem in reactor design is premature fuel-pin failure on account of mechanical interaction between the fuel and the sheath under nonstationary operating conditions. To examine the effects of this interaction on the viability, the authors have built an experimental system with the MR reactor. To provide for varying the power production over wide ranges, gas regulation based on /sup 3/He as neutron absorber is used. A map of core loading in the MR reactor is provided and variation in power in the experimental fuel assembly in accordance with /sup 3/He pressure and control location is shown. A structural diagram shows the reactor apparatus with gas power control in the experimental pin assembly. The relative changes in channel power in relation to neutron absorber pressure in GCU in channel 1-4 are presented. The results are offered on the power variation in the experimental assembly and reactivity as functions of /sup 3/He pressure in the GCU, together with the calculated data.

  15. Studies on the closed-loop digital control of multi-modular reactors

    SciTech Connect

    Bernard, J.A. . Nuclear Reactor Lab.); Henry, A.F.; Lanning, D.D.; Meyer, J.E. . Dept. of Nuclear Engineering)

    1992-11-01

    This report describes the theoretical development and the evaluation via both experiment and simulation of digital methods for the closed-loop control of power, temperature, and steam generator level in multi-modular reactors. The major conclusion of the research reported here is that the technology is currently available to automate many aspects of the operation of multi-modular plants. This will in turn minimize the number of required personnel and thus contain both operating and personnel costs, allow each module to be operated at a different power level thereby staggering the times at which refuelings would be needed, and maintain the competitiveness of US industry relative to foreign vendors who are developing and applying advanced control concepts. The technology described in this report is appropriate to the proposed multi-modular reactor designs and to present-generation pressurized water reactors. Its extension to boiling water reactors is possible provided that the commitment is made to create a real-time model of a BWR. The work reported here was performed by the Massachusetts Institute of Technology (MIT) under contract to the Oak Ridge National Laboratory (ORNL) and to the United States Department of Energy (Division of Industry and University Programs, Contract No. DE-FG07-90ER12930.)

  16. Studies on the closed-loop digital control of multi-modular reactors. Final report

    SciTech Connect

    Bernard, J.A.; Henry, A.F.; Lanning, D.D.; Meyer, J.E.

    1992-11-01

    This report describes the theoretical development and the evaluation via both experiment and simulation of digital methods for the closed-loop control of power, temperature, and steam generator level in multi-modular reactors. The major conclusion of the research reported here is that the technology is currently available to automate many aspects of the operation of multi-modular plants. This will in turn minimize the number of required personnel and thus contain both operating and personnel costs, allow each module to be operated at a different power level thereby staggering the times at which refuelings would be needed, and maintain the competitiveness of US industry relative to foreign vendors who are developing and applying advanced control concepts. The technology described in this report is appropriate to the proposed multi-modular reactor designs and to present-generation pressurized water reactors. Its extension to boiling water reactors is possible provided that the commitment is made to create a real-time model of a BWR. The work reported here was performed by the Massachusetts Institute of Technology (MIT) under contract to the Oak Ridge National Laboratory (ORNL) and to the United States Department of Energy (Division of Industry and University Programs, Contract No. DE-FG07-90ER12930.)

  17. Implementation of a source term control program in a mature boiling water reactor.

    PubMed

    Vargo, G J; Jarvis, A J; Remark, J F

    1991-06-01

    The implementation and results of a source term control program implemented at the James A. FitzPatrick Nuclear Power Plant (JAF), a mature boiling water reactor (BWR) facility that has been in commercial operation since 1975, are discussed. Following a chemical decontamination of the reactor water recirculation piping in the Reload 8/Cycle 9 refueling outage in 1988, hydrogen water chemistry (HWC) and feedwater Zn addition were implemented. This is the first application of both HWC and feedwater Zn addition in a BWR facility. The radiological benefits and impacts of combined operation of HWC and feedwater Zn addition at JAF during Cycle 9 are detailed and summarized. The implementation of hydrogen water chemistry resulted in a significant transport of corrosion products within the reactor coolant system that was greater than anticipated. Feedwater Zn addition appears to be effective in controlling buildup of other activated corrosion products such as 60Co on reactor water recirculation piping; however, adverse impacts were encountered. The major adverse impact of feedwater Zn addition is the production of 65Zn that is released during plant outages and operational transients. PMID:2032839

  18. Pebble Fuel Handling and Reactivity Control for Salt-Cooled High Temperature Reactors

    SciTech Connect

    Peterson, Per; Greenspan, Ehud

    2015-02-09

    This report documents the work completed on the X-PREX facility under NEUP Project 11- 3172. This project seeks to demonstrate the viability of pebble fuel handling and reactivity control for fluoride salt-cooled high-temperature reactors (FHRs). The research results also improve the understanding of pebble motion in helium-cooled reactors, as well as the general, fundamental understanding of low-velocity granular flows. Successful use of pebble fuels in with salt coolants would bring major benefits for high-temperature reactor technology. Pebble fuels enable on-line refueling and operation with low excess reactivity, and thus simpler reactivity control and improved fuel utilization. If fixed fuel designs are used, the power density of salt- cooled reactors is limited to 10 MW/m3 to obtain adequate duration between refueling, but pebble fuels allow power densities in the range of 20 to 30 MW/m3. This can be compared to the typical modular helium reactor power density of 5 MW/m3. Pebble fuels also permit radial zoning in annular cores and use of thorium or graphite pebble blankets to reduce neutron fluences to outer radial reflectors and increase total power production. Combined with high power conversion efficiency, compact low-pressure primary and containment systems, and unique safety characteristics including very large thermal margins (>500°C) to fuel damage during transients and accidents, salt-cooled pebble fuel cores offer the potential to meet the major goals of the Advanced Reactor Concepts Development program to provide electricity at lower cost than light water reactors with improved safety and system performance.This report presents the facility description, experimental results, and supporting simulation methods of the new X-Ray Pebble Recirculation Experiment (X-PREX), which is now operational and being used to collect data on the behavior of slow dense granular flows relevant to pebble bed reactor core designs. The X

  19. CONTROL OF VOLATILE ORGANIC COMPOUNDS BY AN AC ENERGIZED FERROELECTRIC PELLET REACTOR AND A PULSED CORONA REACTOR

    EPA Science Inventory

    The paper gives results of a study to develop baseline engineering data to demonstrate the feasibility of application of plasma reactors to the destruction of various volatile organic compounds at ppm levels. Two laboratory-scale reactors, an alternating current energized ferroel...

  20. Simulation and control of water-gas shift packed bed reactor with inter-stage cooling

    NASA Astrophysics Data System (ADS)

    Saw, S. Z.; Nandong, J.

    2016-03-01

    Water-Gas Shift Reaction (WGSR) has become one of the well-known pathways for H2 production in industries. The issue with WGSR is that it is kinetically favored at high temperatures but thermodynamically favored at low temperatures, thus requiring careful consideration in the control design in order to ensure that the temperature used does not deactivate the catalyst. This paper studies the effect of a reactor arrangement with an inter-stage cooling implemented in the packed bed reactor to look at its effect on outlet temperature. A mathematical model is developed based on one-dimensional heat and mass transfers which incorporate the intra-particle effects. It is shown that the placement of the inter-stage cooling and the outlet temperature exiting the inter-stage cooling have strong influence on the reaction conversion. Several control strategies are explored for the process. It is shown that a feedback- feedforward control strategy using Multi-scale Control (MSC) is effective to regulate the reactor temperature profile which is critical to maintaining the catalysts activity.

  1. Flux stability and power control in the Soviet RBMK-1000 reactors

    SciTech Connect

    Meriwether, G.H.; McNeece, J.P.

    1993-08-01

    As a result of the Chernobyl accident, the Soviets have studied and implemented various design changes to improve the safety of the RBMK reactors. The safety measurements include modifications of the control rod configuration, fuel enrichment increase from 2.0 to 2.4 weight percent U-235, and installation of additional supplemental absorbers. The purpose of this study is to investigate the effects of increased fuel enrichment, different control rod positions, and supplemental absorber loadings on reactivity control, power distribution within the large RBMK core, and relative stability against power oscillations.

  2. Neural network setpoint control of an advanced test reactor experiment loop simulation

    SciTech Connect

    Cordes, G.A.; Bryan, S.R.; Powell, R.H.; Chick, D.R.

    1990-09-01

    This report describes the design, implementation, and application of artificial neural networks to achieve temperature and flow rate control for a simulation of a typical experiment loop in the Advanced Test Reactor (ATR) located at the Idaho National Engineering Laboratory (INEL). The goal of the project was to research multivariate, nonlinear control using neural networks. A loop simulation code was adapted for the project and used to create a training set and test the neural network controller for comparison with the existing loop controllers. The results for three neural network designs are documented and compared with existing loop controller action. The neural network was shown to be as accurate at loop control as the classical controllers in the operating region represented by the training set. 9 refs., 28 figs., 2 tabs.

  3. The Role of Instrumentation and Controls Technology in Enabling Deployment of Small Modular Reactors

    SciTech Connect

    Clayton, Dwight A; Wood, Richard Thomas

    2010-01-01

    The development of deployable small modular reactors (SMRs) will provide the United States with another economically viable energy option, diversify the available nuclear power alternatives for the country, and enhance U.S. economic competitiveness by ensuring a domestic capability to supply demonstrated reactor technology to a growing global market for clean and affordable energy sources. Smaller nuclear power plants match the needs of much of the world that lacks highly stable, densely interconnected electrical grids. SMRs can present lower capital and operating costs than large reactors, allow incremental additions to power generation capacity that closely match load growth and support multiple energy applications (i.e., electricity and process heat). Taking advantage of their smaller size and modern design methodology, safety, security, and proliferation resistance may also be increased. Achieving the benefits of SMR deployment requires a new paradigm for plant design and management to address multi-unit, multi-product-stream generating stations. Realizing the goals of SMR deployment also depends on the resolution of technical challenges related to the unique characteristics of these reactor concepts. This paper discusses the primary issues related to SMR deployment that can be addressed through crosscutting research, development, and demonstration involving instrumentation and controls (I&C) technologies.

  4. The Role of Instrumentation and Control Technology in Enabling Deployment of Small Modular Reactors

    SciTech Connect

    Clayton, Dwight A; Wood, Richard Thomas

    2011-01-01

    The development of deployable small modular reactors (SMRs) will provide the United States with another economically viable energy option, diversify the available nuclear power alternatives for the country, and enhance U.S. economic competitiveness by ensuring a domestic capability to supply demonstrated reactor technology to a growing global market for clean and affordable energy sources. Smaller nuclear power plants match the needs of much of the world that lacks highly stable, densely interconnected electrical grids. SMRs can present lower capital and operating costs than large reactors, allow incremental additions to power generation capacity that closely match load growth and support multiple energy applications (i.e., electricity and process heat). Taking advantage of their smaller size and modern design methodology, safety, security, and proliferation resistance may also be increased. Achieving the benefits of SMR deployment requires a new paradigm for plant design and management to address multi-unit, multi-product-stream generating stations. Realizing the goals of SMR deployment also depends on the resolution of technical challenges related to the unique characteristics of these reactor concepts. This paper discusses the primary issues related to SMR deployment that can be addressed through crosscutting research, development, and demonstration involving instrumentation and controls (I&C) technologies.

  5. Apparatus for high flux photocatalytic pollution control using a rotating fluidized bed reactor

    DOEpatents

    Tabatabaie-Raissi, Ali; Muradov, Nazim Z.; Martin, Eric

    2003-06-24

    An apparatus based on optimizing photoprocess energetics by decoupling of the process energy efficiency from the DRE for target contaminants. The technique is applicable to both low- and high-flux photoreactor design and scale-up. An apparatus for high-flux photocatalytic pollution control is based on the implementation of multifunctional metal oxide aerogels and other media in conjunction with a novel rotating fluidized particle bed reactor.

  6. Temperature control of bench-scaled batch reactor equipped with a monofluid heating/cooling system

    NASA Astrophysics Data System (ADS)

    Teng, Hai-peng; Song, Yi-ming

    2014-04-01

    An advanced control concept, Predictive Functional Control (PFC), is applied for temperature control of a bench-scaled batch reactor equipped with monofluid heating/cooling system. First principles process models are developed. Based on achieved models, significant process variables, which are difficult or impossible to measure online, are estimated from easily measured variables, and cascade PFC control strategy has been projected and implemented in Matlab R14. The dynamics of individual subunits is explicitly taken into consideration by internal model in the control algorithms, and model uncertainty, various process disturbances are compensated by modification of internal model. The experimental results present an excellent capability of tracking the set point, and the success of PFC technique as a process control paradigm is illustratively demonstrated.

  7. Defluoridation of water via electrically controlled anion exchange by polyaniline modified electrode reactor.

    PubMed

    Cui, Hao; Li, Qin; Qian, Yan; Tang, Rong; An, Hao; Zhai, Jianping

    2011-11-01

    A polyaniline (PANI) modified electrode reactor was designed for fluoride removal from aqueous solutions. The innovative concept behind the reactor design is that the uptake and elute of fluoride could be well controlled by modulating the potential of the PANI film. The maximum fluoride removal capacity of PANI is more than 20 mg/g at a positive voltage based on the electrically controlled anion-exchange mechanism. The results of batch tests showed that terminal potential values had a major impact on fluoride removal by this PANI, with optimal removal occurring at 1.5 V. The fluoride removal capacity (q(e)) increased rapidly within 5 min and reached equilibrium within 10 min, which indicated a rapid removal velocity of fluoride by PANI under this condition. The applicability of defluoridation using the PANI reactor to treat fluoride-contaminated tap water was also tested through flow cell breakthrough studies. At initial fluoride concentrations of 5 mg/L and 10 mg/L, the breakthrough capacities were 20.08 mg/g and 19.24 mg/g, respectively. Moreover, during the first half of the period before the breakthrough point, the fluoride concentration of the treated solution was below the WHO's recommended levels (1.5 mg/L). The results of the five consecutive treatment-regeneration studies also showed that the PANI films could be reused. Taken together, these results implied that the electrically controlled anion exchange by the PANI-modified electrode reactor may be an effective technique for the removal of fluoride from water. PMID:21907382

  8. Defluoridation of water via electrically controlled anion exchange by polyaniline modified electrode reactor.

    PubMed

    Cui, Hao; Li, Qin; Qian, Yan; Tang, Rong; An, Hao; Zhai, Jianping

    2011-11-01

    A polyaniline (PANI) modified electrode reactor was designed for fluoride removal from aqueous solutions. The innovative concept behind the reactor design is that the uptake and elute of fluoride could be well controlled by modulating the potential of the PANI film. The maximum fluoride removal capacity of PANI is more than 20 mg/g at a positive voltage based on the electrically controlled anion-exchange mechanism. The results of batch tests showed that terminal potential values had a major impact on fluoride removal by this PANI, with optimal removal occurring at 1.5 V. The fluoride removal capacity (q(e)) increased rapidly within 5 min and reached equilibrium within 10 min, which indicated a rapid removal velocity of fluoride by PANI under this condition. The applicability of defluoridation using the PANI reactor to treat fluoride-contaminated tap water was also tested through flow cell breakthrough studies. At initial fluoride concentrations of 5 mg/L and 10 mg/L, the breakthrough capacities were 20.08 mg/g and 19.24 mg/g, respectively. Moreover, during the first half of the period before the breakthrough point, the fluoride concentration of the treated solution was below the WHO's recommended levels (1.5 mg/L). The results of the five consecutive treatment-regeneration studies also showed that the PANI films could be reused. Taken together, these results implied that the electrically controlled anion exchange by the PANI-modified electrode reactor may be an effective technique for the removal of fluoride from water.

  9. Thermonuclear Supernova Explosions From Hybrid White Dwarf Progenitors

    NASA Astrophysics Data System (ADS)

    Willcox, Donald E.; Townsley, Dean; Calder, Alan; Denissenkov, Pavel; Herwig, Falk

    2016-01-01

    Motivated by recent results in stellar evolution in which convective boundary mixing in SAGB stars can give rise to hybrid white dwarf (WD) stars with a C-O core inside an O-Ne shell, we simulate thermonuclear (Type Ia) supernovae from these hybrid progenitors. We use the FLASH code to perform multidimensional simulations in the deflagration to detonation transition (DDT) explosion paradigm from progenitor models produced with the MESA stellar evolution code that include the thermal energetics of the Urca process. We performed a suite of DDT simulations over a range of ignition conditions and compare to previous results from a suite of C-O white dwarfs. Despite significant variability within each suite, distinguishing trends are apparent in their Ni-56 yields and the kinetic properties of their ejecta. We comment on the feasibility of these hybrid WD explosions as the source of some classes of observed subluminous events. This research was supported in part by the U.S. Department of Energy under grant DE-FG02-87ER40317 and by resources at the Institute for Advanced Computational Science at Stony Brook University. The software used in this work was in part developed by the DOE-supported ASC/Alliances Center for Astrophysical Thermonuclear Flashes at the University of Chicago.

  10. The classification of magnetohydrodynamic regimes of thermonuclear combustion

    SciTech Connect

    Remming, Ian S.; Khokhlov, Alexei M.

    2014-10-10

    Physical properties of magnetohydrodynamic (MHD) reaction fronts are studied as functions of the thermodynamic conditions, and the strength and orientation of the magnetic field in the unburned matter through which the fronts propagate. We determine the conditions for the existence of the various types of MHD reaction fronts and the character of the changes in physical quantities across these reaction fronts. The analysis is carried out in general for a perfect gas equation of state and a constant energy release, and then extended to thermonuclear reaction fronts in degenerate carbon-oxygen mixtures and degenerate helium in conditions typical of Type Ia supernova explosions. We find that as unburned matter enters perpendicular to a reaction front, the release of energy through burning generates shear velocity in the reacting gas that, depending on the type of reaction front, strengthens or weakens the magnetic field. In addition, we find that the steady-state propagation of a reaction front is impossible for certain ranges of magnetic field direction. Our results provide insight into the phenomena of MHD thermonuclear combustion that is relevant to the interpretation of future simulations of SN Ia explosions that have magnetic fields systematically incorporated.

  11. On the implementation of a chain nuclear reaction of thermonuclear fusion on the basis of the p+11B process

    NASA Astrophysics Data System (ADS)

    Belyaev, V. S.; Krainov, V. P.; Zagreev, B. V.; Matafonov, A. P.

    2015-07-01

    Various theoretical and experimental schemes for implementing a thermonuclear reactor on the basis of the p+11B reaction are considered. They include beam collisions, fusion in degenerate plasmas, ignition upon plasma acceleration by ponderomotive forces, and the irradiation of a solid-state target from 11B with a proton beam under conditions of a Coulomb explosion of hydrogen microdrops. The possibility of employing ultra-short high-intensity laser pulses to initiate the p+11B reaction under conditions far from thermodynamic equilibrium is discussed. This and some other weakly radioactive thermonuclear reactions are promising owing to their ecological cleanness—there are virtually no neutrons among fusion products. Nuclear reactions that follow the p+11B reaction may generate high-energy protons, sustaining a chain reaction, and this is an advantage of the p+11B option. The approach used also makes it possible to study nuclear reactions under conditions close to those in the early Universe or in the interior of stars.

  12. Control rod heterogeneity effects in liquid-metal fast breeder reactors: Method developments and experimental validation

    SciTech Connect

    Carta, M.; Granget, G.; Palmiotti, G.; Salvatores, M.; Soule, R.

    1988-11-01

    The control rod worth assessment in a large liquid-metal fast breeder reactor is strongly dependent on the actual arrangement of the absorber pins inside the control rod subassemblies. The so-called heterogeneity effects (i.e., the effects on the rod reactivity of the actual rod internal geometry versus homogenization of the absorber atoms over all the subassembly volume) have been evaluated, using explicit and variational methods to derive appropriate cross sections. An experimental program performed at the MASURCA facility has been used to validate these methods.

  13. Pulse-density modulation control of chemical oscillation far from equilibrium in a droplet open-reactor system.

    PubMed

    Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro

    2016-01-20

    The design, construction and control of artificial self-organized systems modelled on dynamical behaviours of living systems are important issues in biologically inspired engineering. Such systems are usually based on complex reaction dynamics far from equilibrium; therefore, the control of non-equilibrium conditions is required. Here we report a droplet open-reactor system, based on droplet fusion and fission, that achieves dynamical control over chemical fluxes into/out of the reactor for chemical reactions far from equilibrium. We mathematically reveal that the control mechanism is formulated as pulse-density modulation control of the fusion-fission timing. We produce the droplet open-reactor system using microfluidic technologies and then perform external control and autonomous feedback control over autocatalytic chemical oscillation reactions far from equilibrium. We believe that this system will be valuable for the dynamical control over self-organized phenomena far from equilibrium in chemical and biomedical studies.

  14. Pulse-density modulation control of chemical oscillation far from equilibrium in a droplet open-reactor system

    PubMed Central

    Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro

    2016-01-01

    The design, construction and control of artificial self-organized systems modelled on dynamical behaviours of living systems are important issues in biologically inspired engineering. Such systems are usually based on complex reaction dynamics far from equilibrium; therefore, the control of non-equilibrium conditions is required. Here we report a droplet open-reactor system, based on droplet fusion and fission, that achieves dynamical control over chemical fluxes into/out of the reactor for chemical reactions far from equilibrium. We mathematically reveal that the control mechanism is formulated as pulse-density modulation control of the fusion–fission timing. We produce the droplet open-reactor system using microfluidic technologies and then perform external control and autonomous feedback control over autocatalytic chemical oscillation reactions far from equilibrium. We believe that this system will be valuable for the dynamical control over self-organized phenomena far from equilibrium in chemical and biomedical studies. PMID:26786848

  15. Pulse-density modulation control of chemical oscillation far from equilibrium in a droplet open-reactor system

    NASA Astrophysics Data System (ADS)

    Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro

    2016-01-01

    The design, construction and control of artificial self-organized systems modelled on dynamical behaviours of living systems are important issues in biologically inspired engineering. Such systems are usually based on complex reaction dynamics far from equilibrium; therefore, the control of non-equilibrium conditions is required. Here we report a droplet open-reactor system, based on droplet fusion and fission, that achieves dynamical control over chemical fluxes into/out of the reactor for chemical reactions far from equilibrium. We mathematically reveal that the control mechanism is formulated as pulse-density modulation control of the fusion-fission timing. We produce the droplet open-reactor system using microfluidic technologies and then perform external control and autonomous feedback control over autocatalytic chemical oscillation reactions far from equilibrium. We believe that this system will be valuable for the dynamical control over self-organized phenomena far from equilibrium in chemical and biomedical studies.

  16. Fuzzy logic control of water level in advanced boiling water reactor

    SciTech Connect

    Lin, Chaung; Lee, Chi-Szu; Raghavan, R.; Fahrner, D.M.

    1995-12-31

    The feedwater control system in the Advanced Boiling Water Reactor (ABWR) is more challenging to design compared to other control systems in the plant, due to the possible change in level from void collapses and swells during transient events. A basic fuzzy logic controller is developed using a simplified ABWR mathematical model to demonstrate and compare the performance of this controller with a simplified conventional controller. To reduce the design effort, methods are developed to automatically tune the scaling factors and control rules. As a first step in developing the fuzzy controller, a fuzzy controller with a limited number of rules is developed to respond to normal plant transients such as setpoint changes of plant parameters and load demand changes. Various simulations for setpoint and load demand changes of plant performances were conducted to evaluate the modeled fuzzy logic design against the simplified ABWR model control system. The simulation results show that the performance of the fuzzy logic controller is comparable to that of the Proportional-Integral (PI) controller, However, the fuzzy logic controller produced shorter settling time for step setpoint changes compared to the simplified conventional controller.

  17. Monte Carlo simulation of a research reactor with nominal power of 7 MW to design new control safety rods

    NASA Astrophysics Data System (ADS)

    Shoushtari, M. K.; Kakavand, T.; Sadat Kiai, S. M.; Ghaforian, H.

    2010-03-01

    The Monte Carlo simulation has been established for a research reactor with nominal power of 7 MW. A detailed model of the reactor core was employed including standard and control fuel elements, reflectors, irradiation channels, control rods, reactor pool and thermal column. The following physical parameters of reactor core were calculated for the present LEU core: core reactivity ( ρ), control rod (CR) worth, thermal and epithermal neutron flux distributions, shutdown margin and delayed neutron fraction. Reduction of unfavorable effects of blockage probability of control safety rod (CSR)s in their interiors because of not enough space in their sites, and lack of suitable capabilities to fabricate very thin plates for CSR cladding, is the main aim of the present study. Making the absorber rod thinner and CSR cladding thicker by introducing a better blackness absorbing material and a new stainless steel alloy, respectively, are two studied ways to reduce the effects of mentioned problems.

  18. Technical support for the hydrogen control requirement for the EPRI advanced light water reactor requirements document

    SciTech Connect

    Plys, M.G.

    1988-01-01

    Hydrogen could be a significant contributor to severe-accident risk if hydrogen generation and combustion were to lead to containment failure and resulting release of fission products. To eliminate hydrogen as a significant risk contributor for advanced light water reactors (ALWRs), the Electric Power Research Institute (EPRI) ALWR requirements document has imposed a hydrogen control requirement. This requirement specifies an upper limit of 13 dry vol% for the allowable hydrogen concentration in containment. The requirement also considers hydrogen generation during severe accidents and states an upper bound on the hydrogen source equivalent to that generated by oxidizing 75% of the active cladding (commonly stated as 75% metal/water reaction (MWR)). The purpose of this paper is to technically support and substantiate the EPRI ALWR hydrogen requirement. The current understanding of hydrogen generation and combustion is evaluated as it applies to reactor systems, and it is concluded that both experimental results and analytical methods provide a sound technical basis for the requirement.

  19. Startup control of the TOPAZ-II space nuclear reactor. Master`s thesis

    SciTech Connect

    Astrin, C.D.

    1996-09-01

    The Russian designed and manufactured TOPAZ-II Thermionic Nuclear Space Reactor has been supplied to the Ballistic Missile Defense Organization for study as part of the TOPAZ International Program. A Preliminary Nuclear Safety Assessment investigated the readiness to use the TOPAZ-II in support of a Nuclear Electric Propulsion Space Test Mission (NEPSTP). Among the anticipated system modifications required for launching the TOPAZ-II system within safety goals is for a U.S. designed Automatic Control System. The requirements and desired features of such a control system are developed based upon U.S. safety standards. System theory and design are presented in order to establish the basis for development of a hybrid control model from available simulations. The model is verified and then used in exploration of various control schemes and casualty analysis providing groundwork for future Automatic Control System design.

  20. Reactor models for a series of continuous stirred tank reactors with a gas-liquid-solid leaching system: Part I. Surface reaction control

    NASA Astrophysics Data System (ADS)

    Papangelakis, V. G.; Demopoulos, G. P.

    1992-12-01

    In this three-part series of articles, comprehensive three-phase steady-state hydrometallurgical reactor models of the continuous stirred tank reactor (CSTR) type are developed and applied to a commercial (pressure oxidation) process. The key features of the developed models are the coupling of both mass and heat balance equations, the description of the nonisothermal performance (autothermal) of a multistage continuous reactor, and the treatment of multimineral feed materials. The model considers only the oxidation reactions, because they mainly affect the thermal balance of the reactor. The stoichiometries and intrinsic kinetics of the heterogeneous leaching reactions, which are established via independent experiments, are the foundation of the developed model. A three-phase (g-l-s) reaction process might be controlled by either surface reaction control, i.e., the rate(s) of the heterogeneous leaching reaction(s), or by gas transfer control, i.e., the rate of transfer of the gaseous reactant into the liquid phase. In the present article (Part I), the case of surface reaction control is treated. The article addresses, in particular, the following topics: (1) it outlines the basic mass and heat balance equations which describe the performance of a multistage leaching reactor; (2) it presents a continuous function to describe the particle size distribution of the feed; and (3) it develops, on the basis of probability theory, number- and mass-particle size density functions which give the size distribution of particle populations reacting according to the surface reaction control-shrinking core model.

  1. Dynamic Modeling and Control of Nuclear Reactors Coupled to Closed-Loop Brayton Cycle Systems using SIMULINK™

    NASA Astrophysics Data System (ADS)

    Wright, Steven A.; Sanchez, Travis

    2005-02-01

    The operation of space reactors for both in-space and planetary operations will require unprecedented levels of autonomy and control. Development of these autonomous control systems will require dynamic system models, effective control methodologies, and autonomous control logic. This paper briefly describes the results of reactor, power-conversion, and control models that are implemented in SIMULINK™ (Simulink, 2004). SIMULINK™ is a development environment packaged with MatLab™ (MatLab, 2004) that allows the creation of dynamic state flow models. Simulation modules for liquid metal, gas cooled reactors, and electrically heated systems have been developed, as have modules for dynamic power-conversion components such as, ducting, heat exchangers, turbines, compressors, permanent magnet alternators, and load resistors. Various control modules for the reactor and the power-conversion shaft speed have also been developed and simulated. The modules are compiled into libraries and can be easily connected in different ways to explore the operational space of a number of potential reactor, power-conversion system configurations, and control approaches. The modularity and variability of these SIMULINK™ models provides a way to simulate a variety of complete power generation systems. To date, both Liquid Metal Reactors (LMR), Gas Cooled Reactors (GCR), and electric heaters that are coupled to gas-dynamics systems and thermoelectric systems have been simulated and are used to understand the behavior of these systems. Current efforts are focused on improving the fidelity of the existing SIMULINK™ modules, extending them to include isotopic heaters, heat pipes, Stirling engines, and on developing state flow logic to provide intelligent autonomy. The simulation code is called RPC-SIM (Reactor Power and Control-Simulator).

  2. Neural Network with Local Memory for Nuclear Reactor Power Level Control

    SciTech Connect

    Uluyol, Oender; Ragheb, Magdi; Tsoukalas, Lefteri

    2001-02-15

    A methodology is introduced for a neural network with local memory called a multilayered local output gamma feedback (LOGF) neural network within the paradigm of locally-recurrent globally-feedforward neural networks. It appears to be well-suited for the identification, prediction, and control tasks in highly dynamic systems; it allows for the presentation of different timescales through incorporation of a gamma memory. A learning algorithm based on the backpropagation-through-time approach is derived. The spatial and temporal weights of the network are iteratively optimized for a given problem using the derived learning algorithm. As a demonstration of the methodology, it is applied to the task of power level control of a nuclear reactor at different fuel cycle conditions. The results demonstrate that the LOGF neural network controller outperforms the classical as well as the state feedback-assisted classical controllers for reactor power level control by showing a better tracking of the demand power, improving the fuel and exit temperature responses, and by performing robustly in different fuel cycle and power level conditions.

  3. Definition of a Robust Supervisory Control Scheme for Sodium-Cooled Fast Reactors

    SciTech Connect

    Ponciroli, Roberto; Passerini, Stefano; Vilim, Richard B.

    2016-01-01

    In this work, an innovative control approach for metal-fueled Sodium-cooled Fast Reactors is proposed. With respect to the classical approach adopted for base-load Nuclear Power Plants, an alternative control strategy for operating the reactor at different power levels by respecting the system physical constraints is presented. In order to achieve a higher operational flexibility along with ensuring that the implemented control loops do not influence the system inherent passive safety features, a dedicated supervisory control scheme for the dynamic definition of the corresponding set-points to be supplied to the PID controllers is designed. In particular, the traditional approach based on the adoption of tabulated lookup tables for the set-point definition is found not to be robust enough when failures of the implemented SISO (Single Input Single Output) actuators occur. Therefore, a feedback algorithm based on the Reference Governor approach, which allows for the optimization of reference signals according to the system operating conditions, is proposed.

  4. Relativistic outflow from two thermonuclear shell flashes on neutron stars

    NASA Astrophysics Data System (ADS)

    in't Zand, J. J. M.; Keek, L.; Cavecchi, Y.

    2014-08-01

    We study the exceptionally short (32-43 ms) precursors of two intermediate-duration thermonuclear X-ray bursts observed with the Rossi X-ray Timing Explorer from the neutron stars in 4U 0614+09 and 2S 0918-549. They exhibit photon fluxes that surpass those at the Eddington limit later in the burst by factors of 2.6 to 3.1. We are able to explain both the short duration and the super-Eddington flux by mildly relativistic outflow velocities of 0.1c to 0.3c subsequent to the thermonuclear shell flashes on the neutron stars. These are the highest velocities ever measured from any thermonuclear flash. The precursor rise times are also exceptionally short: about 1 ms. This is inconsistent with predictions for nuclear flames spreading laterally as deflagrations and suggests detonations instead. This is the first time that a detonation is suggested for such a shallow ignition column depth (yign ≈ 1010 g cm-2). The detonation would possibly require a faster nuclear reaction chain, such as bypassing the α-capture on 12C with the much faster 12C(p,γ)13N(α,p)16O process previously proposed. We confirm the possibility of a detonation, albeit only in the radial direction, through the simulation of the nuclear burning with a large nuclear network and at the appropriate ignition depth, although it remains to be seen whether the Zel'dovich criterion is met. A detonation would also provide the fast flame spreading over the surface of the neutron star to allow for the short rise times. This needs to be supported by future two-dimensional calculations of flame spreading at the relevant column depth. As an alternative to the detonation scenario, we speculate on the possibility that the whole neutron star surface burns almost instantly in the auto-ignition regime. This is motivated by the presence of 150 ms precursors with 30 ms rise times in some superexpansion bursts from 4U 1820-30 at low ignition column depths of ~108 g cm-2.

  5. Formulation and experimental evaluation of closed-form control laws for the rapid maneuvering of reactor neutronic power

    SciTech Connect

    Bernard, J.A. . Nuclear Reactor Lab.)

    1989-09-01

    This report describes both the theoretical development and the experimental evaluation of a novel, robust methodology for the time-optimal adjustment of a reactor's neutronic power under conditions of closed-loop digital control. Central to the approach are the MIT-SNL Period-Generated Minimum Time Control Laws' which determine the rate at which reactivity should be changed in order to cause a reactor's neutronic power to conform to a specified trajectory. Using these laws, reactor power can be safely raised by five to seven orders of magnitude in a few seconds. The MIT-SNL laws were developed to facilitate rapid increases of neutronic power on spacecraft reactors operating in an SDI environment. However, these laws are generic and have other applications including the rapid recovery of research and test reactors subsequent to an unanticipated shutdown, power increases following the achievement of criticality on commercial reactors, power adjustments on commercial reactors so as to minimize thermal stress, and automated startups. The work reported here was performed by the Massachusetts Institute of Technology under contract to the Sandia National Laboratories. Support was also provided by the US Department of Energy's Division of University and Industry Programs. The work described in this report is significant in that a novel solution to the problem of time-optimal control of neutronic power was identified, in that a rigorous description of a reactor's dynamics was derived in that the rate of change of reactivity was recognized as the proper control signal, and in that extensive experimental trials were conducted of these newly developed concepts on actual nuclear reactors. 43 refs., 118 figs., 11 tabs.

  6. Method of vibrational control in the problem of stabilization of chemical reactors. Progress report, July 1, 1981-June 30, 1982

    SciTech Connect

    Meerkov, S.M.

    1982-03-01

    The results obtained during the second year of the three years study of vibrational control application to the problem of stabilization of chemical reactors are presented. The main objective was the development of a nonlinear approach to analytical and numerical investigation of the properties of chemical reactors with oscillating parameters. This objective was achieved and the following results were obtained. Nonlinear vibrational control theory was applied to two types of chemical reactors, the Catalytic Reactor and Continuous Stirred Tank Reactor. It was shown that introduction of sufficiently fast oscillations results in a decrease of the negative slope part (unstable area) of the reactor steady state characteristic. Consequently, the steady states, corresponding to larger productivity, are stabilized. A simulation program was developed and the numerical investigation of reactors with oscillating parameters was carried out. Experiments with the program showed that: the averaged description yields an adequate precision if epsilon = 1/T/sub r/..omega.. approx. = 0.16 (..omega.. is the frequency of introduced vibrations and T/sub r/ is the rise time of the system without vibrations); and the admissible vibrations could result in an increase in productivity of the reactor by a factor of 2/3. On the basis of numerical simulations, the following phenomena were discovered: stabilization of unstable steady states by small and slow oscillations; enlargement of the attraction domain of stable steady states due to medium amplitude and frequency oscillations; and destruction of limit cycles by any types of oscillations. None of these phenomena has theoretical explanations. A basis of vibrational control theory for distributed parameter systems was established. This opened the possibility for vibrational control applications to chemical reactors described by partial differential equation.

  7. Controlling hyperhydration of carnations (Dianthus caryophyllus L.) grown in a mist reactor.

    PubMed

    Correll, M J; Wu, Y; Weathers, P J

    Carnations (Dianthus caryophyllus L.) grown in vitro often develop physiological abnormalities such as hyperhydration. The amount of hyperhydration and growth was compared between carnations grown in mist reactors and conventional semisolid micropropagation systems (vented or unvented GA7 culture boxes). Plants grown in the mist reactor with long misting times (10 min h(-1)) produced more dry mass than those grown with <10 min h(-1); however, more misting also produced more hyperhydrated plants (70% hyperhydration). Control of hyperhydration in the mist reactor involved either reducing the overall nutrient mist supply or altering the mist supply throughout the culturing period. Stepped decreases in the mist supply throughout the 3-week period or an overall decrease in the duration of misting reduced hyperhydration to 13% and 5%, respectively. However, for both misting regimes, the biomass of normal (healthy) plants (fresh and dry weights) was limited. Further analysis suggested that, although normal plant biomass increased with longer mist exposure, hyperhydration levels also increased while the water content, based on percent dry weight, approached that of hyperhydrated plants. Sufficient normal plant development (fresh weight, leaf and shoot numbers, height, and rooting) with < 50% hyperhydration was obtained by weekly, stepped increases in the nutrient mist supply.

  8. Trends vs. reactor size of passive reactivity shutdown and control performance

    SciTech Connect

    Wade, D.C.; Fujita, E.K.

    1987-01-01

    For LMR concepts, the goal of passive reactivity shutdown has been approached in the US by designing the reactors for favorable relationships among the power, power/flow, and inlet temperature coefficients of reactivity, for high internal conversion ratio (yielding small burnup control swing), and for a primary pump coastdown time appropriately matched to the delayed neutron hold back of power decay upon negative reactivity input. The use of sodium bonded metallic fuel pins has facilitated the achievement of the massive shutdown design goals as a consequence of their high thermal conductivity and high effective heavy metal density. Alternately, core designs based on derated oxide pins may be able to achieve the passive shutdown features at the cost of larger core volume and increased initial fissile inventory. For LMR concepts, the passive decay heat removal goal of inherent safety has been approached in US designs by use of pool layouts, larger surface to volume ratio of the reactor vessel with natural draft air cooling of the vessel surface, elevations and redans which promote natural circulation through the core, and thermal mass of the pool contents sufficient to absorb that initial transient decay heat which exceeds the natural draft air cooling capacity. This paper describes current US ''inherently safe'' reactor design.

  9. Conceptual design of a pressure tube light water reactor with variable moderator control

    SciTech Connect

    Rachamin, R.; Fridman, E.; Galperin, A.

    2012-07-01

    This paper presents the development of innovative pressure tube light water reactor with variable moderator control. The core layout is derived from a CANDU line of reactors in general, and advanced ACR-1000 design in particular. It should be stressed however, that while some of the ACR-1000 mechanical design features are adopted, the core design basics of the reactor proposed here are completely different. First, the inter fuel channels spacing, surrounded by the calandria tank, contains a low pressure gas instead of heavy water moderator. Second, the fuel channel design features an additional/external tube (designated as moderator tube) connected to a separate moderator management system. The moderator management system is design to vary the moderator tube content from 'dry' (gas) to 'flooded' (light water filled). The dynamic variation of the moderator is a unique and very important feature of the proposed design. The moderator variation allows an implementation of the 'breed and burn' mode of operation. The 'breed and burn' mode of operation is implemented by keeping the moderator tube empty ('dry' filled with gas) during the breed part of the fuel depletion and subsequently introducing the moderator by 'flooding' the moderator tube for the 'burn' part. This paper assesses the conceptual feasibility of the proposed concept from a neutronics point of view. (authors)

  10. EPRI`s nuclear power plant instrumentation and control program and its applicability to advanced reactors

    SciTech Connect

    Naser, J.; Torok, R.; Wilkinson, D.

    1997-12-01

    I&C systems in nuclear power plants need to be upgraded over the lifetime of the plant in a reliable and cost-effective manner to replace obsolete equipment, to reduce O&M costs, to improve plant performance, and to maintain safety. This applies to operating plants now and will apply to advanced reactors in the future. The major drivers for the replacement of the safety, control, and information systems in nuclear power plants are the obsolescence of the existing hardware and the need for more cost-effective power production. Competition between power producers is dictating more cost-effective power production. The increasing O&M costs to maintain systems experiencing obsolescence problems is counter to the needs for more cost-effective power production and improved competitiveness. This need for increased productivity applies to government facilities as well as commercial plants. Increasing competition will continue to be a major factor in the operation of both operating plants and advanced reactors. It will continue to dictate the need for improved productivity and cost-effectiveness. EPRI and its member nuclear utilities are working together on an industry wide I&C Program to address I&C issues and to develop cost-effective solutions. A majority of the I&C products and demonstrations being developed under this program will benefit advanced reactors in both the design and operational phases of their life cycle as well as it will benefit existing plants. 20 refs.

  11. Application of fuzzy logic in nuclear reactor control Part I: An assessment of state-of-the-art

    SciTech Connect

    Herger, A.S.; Jamshidl, M.; Alang-Rashid, N.K.

    1995-10-01

    This article discusses the application of fuzzy logic to nuclear reactor control. The method has been suggested by many investigators in many control applications. Reviews of the application of fuzzy logic in process control are given by Tong and Sugeno. Because fuzzy logic control (FLC) provides a pathway for transforming human abstractions into the numerical domain, it has the potential to assist nuclear reactor operators in the control room. With this transformation, linguistically expressed control principles can be coded into the fuzzy controller rule base. Having acquired the skill of the operators, the FLC can assist an operator in controlling the complex system. The thrust of FLC is to derive a conceptual model of the control operation, without expressing the process as mathematical equations, to assist the human operator in interpreting incoming plant variables and arriving at a proper control action. To introduce the concept of FLC in nuclear reactor operation, an overview of the mythology and a review of its application in both nuclear and nonnuclear control application domains are presented along with subsequent discussion of fuzzy logic controllers, their structures, and their method of information processing. The article concludes with the application of a tunable FLC to a typical reactor control problem.

  12. Application of fuzzy logic in nuclear reactor control: Part 1: An assessment of state-of-the-art

    SciTech Connect

    Heger, A.S.; Alang-Rashid, N.K.; Jamshidi, M.

    1995-01-01

    This article discusses the application of fuzzy logic of nuclear reactor control. The method has been suggested by many investigators in many control applications. Reviews of the application of fuzzy logic in process control are given by Tong and Sugeno. Because fuzzy logic control (FLC) provides a pathway for transforming human abstractions into the numerical domain, it has the potential to assist nuclear reactor operators in the control room. With this transformation, linguistically expressed control principles can be coded into the fuzzy controller rule base. Having acquired the skill of he operators, the FLC can assist an operator in controlling the complex system. The thrust of FLC is to derive a conceptual model of the control operation, without expressing the process as mathematical equations, to assist the human operator in interpreting incoming plant variables and arriving at a proper control action. To introduce the concept of FLC in nuclear reactor operation, an overview of the mythology and a review of its application in both nuclear and nonnuclear control application domains are presented along with subsequent discussion of fuzzy logic controllers, their structures, and their method of information processing. The article concludes with the application of a tunable FLC to a typical reactor control problem. 49 refs., 9 figs., 3 tabs.

  13. Light Water Reactor Sustainability Program A Reference Plan for Control Room Modernization: Planning and Analysis Phase

    SciTech Connect

    Jacques Hugo; Ronald Boring; Lew Hanes; Kenneth Thomas

    2013-09-01

    The U.S. Department of Energy’s Light Water Reactor Sustainability (LWRS) program is collaborating with a U.S. nuclear utility to bring about a systematic fleet-wide control room modernization. To facilitate this upgrade, a new distributed control system (DCS) is being introduced into the control rooms of these plants. The DCS will upgrade the legacy plant process computer and emergency response facility information system. In addition, the DCS will replace an existing analog turbine control system with a display-based system. With technology upgrades comes the opportunity to improve the overall human-system interaction between the operators and the control room. To optimize operator performance, the LWRS Control Room Modernization research team followed a human-centered approach published by the U.S. Nuclear Regulatory Commission. NUREG-0711, Rev. 3, Human Factors Engineering Program Review Model (O’Hara et al., 2012), prescribes four phases for human factors engineering. This report provides examples of the first phase, Planning and Analysis. The three elements of Planning and Analysis in NUREG-0711 that are most crucial to initiating control room upgrades are: • Operating Experience Review: Identifies opportunities for improvement in the existing system and provides lessons learned from implemented systems. • Function Analysis and Allocation: Identifies which functions at the plant may be optimally handled by the DCS vs. the operators. • Task Analysis: Identifies how tasks might be optimized for the operators. Each of these elements is covered in a separate chapter. Examples are drawn from workshops with reactor operators that were conducted at the LWRS Human System Simulation Laboratory HSSL and at the respective plants. The findings in this report represent generalized accounts of more detailed proprietary reports produced for the utility for each plant. The goal of this LWRS report is to disseminate the technique and provide examples sufficient to

  14. The dynamic mutation characteristics of thermonuclear reaction in Tokamak.

    PubMed

    Li, Jing; Quan, Tingting; Zhang, Wei; Deng, Wei

    2014-01-01

    The stability and bifurcations of multiple limit cycles for the physical model of thermonuclear reaction in Tokamak are investigated in this paper. The one-dimensional Ginzburg-Landau type perturbed diffusion equations for the density of the plasma and the radial electric field near the plasma edge in Tokamak are established. First, the equations are transformed to the average equations with the method of multiple scales and the average equations turn to be a Z 2-symmetric perturbed polynomial Hamiltonian system of degree 5. Then, with the bifurcations theory and method of detection function, the qualitative behavior of the unperturbed system and the number of the limit cycles of the perturbed system for certain groups of parameter are analyzed. At last, the stability of the limit cycles is studied and the physical meaning of Tokamak equations under these parameter groups is given.

  15. NASA superconducting magnetic mirror facility. [for thermonuclear research

    NASA Technical Reports Server (NTRS)

    Reinmann, J. J.; Swanson, M. C.; Nichols, C. R.; Bloy, S. J.; Nagy, L. A.; Brady, F. J.

    1973-01-01

    The design details and initial test results of a superconducting magnetic mirror facility that has been constructed at NASA Lewis Research Center for use in thermonuclear research are summarized. The magnet system consists of four solenoidal coils which are individually rated at 5.0 T. Each coll is composed of an inner, middle, and outer winding. The inner winding is wound of stabilized Nb3Sn superconducting ribbon, and the middle and outer windings are wound of stabilized Nb-Ti superconducting wire. When arranged in the mirror geometry, the four coils will produce 8.7 T at the mirrors and a 1.8 mirror ratio. The magnet has a 41-cm diameter clear bore which is open to atmosphere. Distance between the mirrors is 111 cm. Presently there are only three magnets in the facility; the fourth magnet is being rebuilt.

  16. A compilation of charged-particle induced thermonuclear reaction rates

    NASA Astrophysics Data System (ADS)

    Angulo, C.; Arnould, M.; Rayet, M.; Descouvemont, P.; Baye, D.; Leclercq-Willain, C.; Coc, A.; Barhoumi, S.; Aguer, P.; Rolfs, C.; Kunz, R.; Hammer, J. W.; Mayer, A.; Paradellis, T.; Kossionides, S.; Chronidou, C.; Spyrou, K.; degl'Innocenti, S.; Fiorentini, G.; Ricci, B.; Zavatarelli, S.; Providencia, C.; Wolters, H.; Soares, J.; Grama, C.; Rahighi, J.; Shotter, A.; Lamehi Rachti, M.

    1999-08-01

    Low-energy cross section data for 86 charged-particle induced reactions involving light (1 <=Z <=14), mostly stable, nuclei are compiled. The corresponding Maxwellian-averaged thermonuclear reaction rates of relevance in astrophysical plasmas at temperatures in the range from 106 K to 1010 K are calculated. These evaluations assume either that the target nuclei are in their ground state, or that the target states are thermally populated following a Maxwell-Boltzmann distribution, except in some cases involving isomeric states. Adopted values complemented with lower and upper limits of the rates are presented in tabular form. Analytical approximations to the adopted rates, as well as to the inverse/direct rate ratios, are provided.

  17. Hot subdwarf stars and their connection to thermonuclear supernovae

    NASA Astrophysics Data System (ADS)

    Geier, S.; Kupfer, T.; Ziegerer, E.; Heber, U.; Németh, P.; Irrgang, A.; pre=", team

    2016-07-01

    Hot subdwarf stars (sdO/Bs) are evolved core helium-burning stars with very thin hydrogen envelopes, which can be formed by common envelope ejection. Close sdB binaries with massive white dwarf (WD) companions are potential progenitors of thermonuclear supernovae type Ia (SN Ia). We discovered such a progenitor candidate as well as a candidate for a surviving companion star, which escapes from the Galaxy. More candidates for both types of objects have been found by crossmatching known sdB stars with proper motion and light curve catalogues. The Gaia mission will provide accurate astrometry and light curves of all the stars in our hot subdwarf sample and will allow us to compile a much larger all-sky catalogue of those stars. In this way we expect to find hundreds of progenitor binaries and ejected companions.

  18. Influence of thermonuclear effects on the collapse of supermassive stars

    NASA Astrophysics Data System (ADS)

    Montero, Pedro J.; Janka, H.-T.; Müller, E.; Müller, B.

    2011-09-01

    We present results of general relativistic simulations of collapsing supermassive stars using the two-dimensional general relativistic numerical code Nada, which solves the Einstein equations written in the BSSN formalism and the general relativistic hydrodynamic equations with high resolution shock capturing schemes. These numerical simulations use a tabulated equation of state which includes effects of radiation and gas pressure, and those associated with the electron-positron pairs. We also take into account the effect of thermonuclear energy released by hydrogen and helium burning. We find that objects with mass ≈ 5 × 105M and initial metallicity greater than ZCNO ≈ 0.004 do explode if non-rotating, while the threshold metallicity for an explosion is reduced to ZCNO ≈ 0.002 for objects uniformly rotating.

  19. The Dynamic Mutation Characteristics of Thermonuclear Reaction in Tokamak

    PubMed Central

    Li, Jing; Quan, Tingting; Zhang, Wei; Deng, Wei

    2014-01-01

    The stability and bifurcations of multiple limit cycles for the physical model of thermonuclear reaction in Tokamak are investigated in this paper. The one-dimensional Ginzburg-Landau type perturbed diffusion equations for the density of the plasma and the radial electric field near the plasma edge in Tokamak are established. First, the equations are transformed to the average equations with the method of multiple scales and the average equations turn to be a Z2-symmetric perturbed polynomial Hamiltonian system of degree 5. Then, with the bifurcations theory and method of detection function, the qualitative behavior of the unperturbed system and the number of the limit cycles of the perturbed system for certain groups of parameter are analyzed. At last, the stability of the limit cycles is studied and the physical meaning of Tokamak equations under these parameter groups is given. PMID:24892099

  20. The Thermonuclear Runaway and the Classical Nova Outburst

    NASA Astrophysics Data System (ADS)

    Starrfield, S.; Iliadis, C.; Hix, W. R.

    2016-05-01

    Nova explosions occur on the white dwarf component of a cataclysmic variable binary stellar system that is accreting matter lost by its companion. When sufficient material has been accreted by the white dwarf, a thermonuclear runaway occurs and ejects material in what is observed as a classical nova explosion. We describe both the recent advances in our understanding of the progress of the outburst and outline some of the puzzles that are still outstanding. We report on the effects of improving both the nuclear reaction rate library and including a modern nuclear reaction network in our one-dimensional, fully implicit, hydrodynamic computer code. In addition, there has been progress in observational studies of supernovae Ia with implications about the progenitors, and we discuss that in this review.

  1. Detonating Failed Deflagration Model of Thermonuclear Supernovae. I. Explosion Dynamics

    NASA Astrophysics Data System (ADS)

    Plewa, Tomasz

    2007-03-01

    We present a detonating failed deflagration model of Type Ia supernovae. In this model, the thermonuclear explosion of a massive white dwarf follows an off-center deflagration. We conduct a survey of asymmetric ignition configurations initiated at various distances from the stellar center. In all cases studied, we find that only a small amount of stellar fuel is consumed during deflagration phase, no explosion is obtained, and the released energy is mostly wasted on expanding the progenitor. Products of the failed deflagration quickly reach the stellar surface, polluting and strongly disturbing it. These disturbances eventually evolve into small and isolated shock-dominated regions that are rich in fuel. We consider these regions as seeds capable of forming self-sustained detonations that, ultimately, result in the thermonuclear supernova explosion. Preliminary nucleosynthesis results indicate that the model supernova ejecta are typically composed of about 0.1-0.25 Msolar of silicon group elements and 0.9-1.2 Msolar of iron group elements and are essentially carbon-free. The ejecta have a composite morphology, are chemically stratified, and display a modest amount of intrinsic asymmetry. The innermost layers are slightly egg shaped with the axis ratio ~1.2-1.3 and dominated by the products of silicon burning. This central region is surrounded by a shell of silicon group elements. The outermost layers of ejecta are highly inhomogeneous and contain products of incomplete oxygen burning with only small admixture of unburned stellar material. The explosion energies are ~(1.3-1.5)×1051 ergs.

  2. Advanced Instrumentation and Control Methods for Small and Medium Reactors with IRIS Demonstration

    SciTech Connect

    J. Wesley Hines; Belle R. Upadhyaya; J. Michael Doster; Robert M. Edwards; Kenneth D. Lewis; Paul Turinsky; Jamie Coble

    2011-05-31

    Development and deployment of small-scale nuclear power reactors and their maintenance, monitoring, and control are part of the mission under the Small Modular Reactor (SMR) program. The objectives of this NERI-consortium research project are to investigate, develop, and validate advanced methods for sensing, controlling, monitoring, diagnosis, and prognosis of these reactors, and to demonstrate the methods with application to one of the proposed integral pressurized water reactors (IPWR). For this project, the IPWR design by Westinghouse, the International Reactor Secure and Innovative (IRIS), has been used to demonstrate the techniques developed under this project. The research focuses on three topical areas with the following objectives. Objective 1 - Develop and apply simulation capabilities and sensitivity/uncertainty analysis methods to address sensor deployment analysis and small grid stability issues. Objective 2 - Develop and test an autonomous and fault-tolerant control architecture and apply to the IRIS system and an experimental flow control loop, with extensions to multiple reactor modules, nuclear desalination, and optimal sensor placement strategy. Objective 3 - Develop and test an integrated monitoring, diagnosis, and prognosis system for SMRs using the IRIS as a test platform, and integrate process and equipment monitoring (PEM) and process and equipment prognostics (PEP) toolboxes. The research tasks are focused on meeting the unique needs of reactors that may be deployed to remote locations or to developing countries with limited support infrastructure. These applications will require smaller, robust reactor designs with advanced technologies for sensors, instrumentation, and control. An excellent overview of SMRs is described in an article by Ingersoll (2009). The article refers to these as deliberately small reactors. Most of these have modular characteristics, with multiple units deployed at the same plant site. Additionally, the topics focus

  3. U.S. Department of Energy Instrumentation and Controls Technology Research for Advanced Small Modular Reactors

    SciTech Connect

    Wood, Richard Thomas

    2012-01-01

    Instrumentation, controls, and human-machine interfaces (ICHMI) are essential enabling technologies that strongly influence nuclear power plant performance and operational costs. The U.S. Department of Energy (DOE) has recognized that ICHMI research, development, and demonstration (RD&D) is needed to resolve the technical challenges that may compromise the effective and efficient utilization of modern ICHMI technology and consequently inhibit realization of the benefits offered by expanded utilization of nuclear power. Consequently, key DOE programs have substantial ICHMI RD&D elements to their respective research portfolio. This article describes current ICHMI research to support the development of advanced small modular reactors.

  4. A two-step method for developing a control rod program for boiling water reactors

    SciTech Connect

    Taner, M.S.; Levine, S.H. ); Hsiao, M.Y. )

    1992-01-01

    This paper reports on a two-step method that is established for the generation of a long-term control rod program for boiling water reactors (BWRs). The new method assumes a time-variant target power distribution in core depletion. In the new method, the BWR control rod programming is divided into two steps. In step 1, a sequence of optimal, exposure-dependent Haling power distribution profiles is generated, utilizing the spectral shift concept. In step 2, a set of exposure-dependent control rod patterns is developed by using the Haling profiles generated at step 1 as a target. The new method is implemented in a computer program named OCTOPUS. The optimization procedure of OCTOPUS is based on the method of approximation programming, in which the SIMULATE-E code is used to determine the nucleonics characteristics of the reactor core state. In a test in cycle length over a time-invariant, target Haling power distribution case because of a moderate application of spectral shift. No thermal limits of the core were violated. The gain in cycle length could be increased further by broadening the extent of the spetral shift.

  5. Instrumentation, Controls, and Human-Machine Interface Technology Development Roadmap in Support of Grid Appropriate Reactors

    SciTech Connect

    Holcomb, David Eugene; Upadhyaya, Belle R.; Kisner, Roger A; O'Hara, John; Quinn, Edward L.; Miller, Don W.

    2009-01-01

    Grid Appropriate Reactors (GARs) are a component of the U.S. Department of Energy s (DOE s) Global Nuclear Energy Partnership (GNEP) program. GARs have smaller output power (<~600 MWe), than those intended for deployment on large, tightly coupled grids. This smaller size is important in avoiding grid destabilization, which can result from having a large fraction of a grid s electrical generation supplied by a single source. GARs are envisioned to be deployed worldwide often in locations without extensive nuclear power experience. DOE recently sponsored the creation of an Instrumentation, Controls, and Human-Machine Interface (ICHMI) technology development roadmap emphasizing the specific characteristics of GARs [1]. This roadmapping effort builds upon and focuses the recently developed, more general nuclear energy ICHMI technology development roadmap [2]. The combination of the smaller plant size, smaller grids, and deployment in locations without extensive prior nuclear power experience presents particular infrastructure, regulation, design, operational, and safeguards challenges for effective GAR deployment. ICHMI technologies are central to efficient GAR operation and as such are a dimension of each of these challenges. Further, while the particular ICHMI technologies to be developed would be useful at larger power plants, they are not high-priority development items at the larger plants. For example, grid transient resilience would be a useful feature for any reactor/grid combination and indeed would have limited some recent blackout events. However, most large reactors have limited passive cooling features. Large plants with active safety response features will likely preserve trip preferential grid transient response. This contrasts sharply with GARs featuring passive shutdown cooling, which can safely support grid stability during large grid transients. ICHMI technologies ranging from alternative control algorithms to simplified human-interface system

  6. NUCLEAR REACTOR

    DOEpatents

    Moore, R.V.; Bowen, J.H.; Dent, K.H.

    1958-12-01

    A heterogeneous, natural uranium fueled, solid moderated, gas cooled reactor is described, in which the fuel elements are in the form of elongated rods and are dlsposed within vertical coolant channels ln the moderator symmetrically arranged as a regular lattice in groups. This reactor employs control rods which operate in vertical channels in the moderator so that each control rod is centered in one of the fuel element groups. The reactor is enclosed in a pressure vessel which ls provided with access holes at the top to facilitate loading and unloadlng of the fuel elements, control rods and control rod driving devices.

  7. Heat Transfer Salts for Nuclear Reactor Systems - Chemistry Control, Corrosion Mitigation, and Modeling

    SciTech Connect

    Anderson, Mark; Sridharan, Kumar; Morgan, Dane; Peterson, Per; Calderoni, Pattrick; Scheele, Randall; Casekka, Andrew; McNamara, Bruce

    2015-01-22

    The concept of a molten salt reactor has existed for nearly sixty years. Previously all work was done during a large collaborative effort at Oak Ridge National Laboratory, culminating in a research reactor which operated for 15,000 hours without major error. This technical success has garnished interest in modern, high temperature, reactor schemes. Research using molten fluoride salts for nuclear applications requires a steady supply of high grade molten salts. There is no bulk supplier of research grade fluoride salts in the world, so a facility which could provide all the salt needed for testing at the University of Wisconsin had to be produced. Two salt purification devices were made for this purpose, a large scale purifier, and a small scale purifier, each designed to clean the salts from impurities and reduce their corrosion potential. As of now, the small scale has performed with flibe salt, hydrogen, and hydrogen fluoride, yielding clean salt. This salt is currently being used in corrosion testing facilities at the Massachusetts Institute of Technology and the University of Wisconsin. Working with the beryllium based salts requires extensive safety measures and health monitoring to prevent the development of acute or chronic beryllium disease, two pulmonary diseases created by an allergic reaction to beryllium in the lungs. Extensive health monitoring, engineering controls, and environment monitoring had to be set up with the University of Wisconsin department of Environment, Health and Safety. The hydrogen fluoride required for purification was also an extreme health hazard requiring thoughtful planning and execution. These dangers have made research a slow and tedious process. Simple processes, such as chemical handling and clean-up, can take large amounts of ingenuity and time. Other work has complemented the experimental research at Wisconsin to advance high temperature reactor goals. Modeling work has been performed in house to re

  8. A mixed flow reactor method to synthesize amorphous calcium carbonate under controlled chemical conditions.

    PubMed

    Blue, Christina R; Rimstidt, J Donald; Dove, Patricia M

    2013-01-01

    This study describes a new procedure to synthesize amorphous calcium carbonate (ACC) from well-characterized solutions that maintain a constant supersaturation. The method uses a mixed flow reactor to prepare ACC in significant quantities with consistent compositions. The experimental design utilizes a high-precision solution pump that enables the reactant solution to continuously flow through the reactor under constant mixing and allows the precipitation of ACC to reach steady state. As a proof of concept, we produced ACC with controlled Mg contents by regulating the Mg/Ca ratio of the input solution and the carbonate concentration and pH. Our findings show that the Mg/Ca ratio of the reactant solution is the primary control for the Mg content in ACC, as shown in previous studies, but ACC composition is further regulated by the carbonate concentration and pH of the reactant solution. The method offers promise for quantitative studies of ACC composition and properties and for investigating the role of this phase as a reactive precursor to biogenic minerals.

  9. Measurement control design and performance assessment in the Integral Fast Reactor fuel cycle

    SciTech Connect

    Orechwa, Y.; Bucher, R.G.

    1994-08-01

    The Integral Fast Reactor (IFR)--consisting of a metal fueled and liquid metal cooled reactor together with an attendant fuel cycle facility (FCF)--is currently undergoing a phased demonstration of the closed fuel cycle at Argonne National Laboratory. The recycle technology is pyrometalurgical based with incomplete fission product separation and all transuranics following plutonium for recycle. The equipment operates in batch mode at 500 to 1,300 C. The materials are highly radioactive and pyrophoric, thus the FCF requires remote operation. Central to the material control and accounting system for the FCF are the balances for mass measurements. The remote operation of the balances limits direct adjustment. The radiation environment requires that removal and replacement of the balances be minimized. The uniqueness of the facility precludes historical data for design and performance assessment. To assure efficient operation of the facility, the design of the measurement control system has called for procedures which assess the performance of the balances in great detail and will support capabilities for the correction of systematic changes in the performance of the balances through software.

  10. A Review of Tribological Coatings for Control Drive Mechanisms in Space Reactors

    SciTech Connect

    CJ Larkin; JD Edington; BJ Close

    2006-02-21

    Tribological coatings must provide lubrication for moving components of the control drive mechanism for a space reactor and prevent seizing due to friction or diffusion welding to provide highly reliable and precise control of reflector position over the mission lifetime. Several coatings were evaluated based on tribological performance at elevated temperatures and in ultrahigh vacuum environments. Candidates with proven performance in the anticipated environment are limited primarily to disulfide materials. Irradiation data for these coatings is nonexistent. Compatibility issues between coating materials and structural components may require the use of barrier layers between the solid lubricant and structural components to prevent deleterious interactions. It would be advisable to consider possible lubricant interactions prior to down-selection of structural materials. A battery of tests was proposed to provide the necessary data for eventual solid lubricant/coating selection.

  11. Research and development on the application of advanced control technologies to advanced nuclear reactor systems: A US national perspective

    SciTech Connect

    White, J.D.; Monson, L.R.; Carrol, D.G.; Dayal, Y.; Argonne National Lab., IL; General Electric Co., San Jose, CA )

    1989-01-01

    Control system designs for nuclear power plants are becoming more advanced through the use of digital technology and automation. This evolution is taking place because of: (1) the limitations in analog based control system performance and maintenance and availability and (2) the promise of significant improvement in plant operation and availability due to advances in digital and other control technologies. Digital retrofits of control systems in US nuclear plants are occurring now. Designs of control and protection systems for advanced LWRs are based on digital technology. The use of small inexpensive, fast, large-capacity computers in these designs is the first step of an evolutionary process described in this paper. Under the sponsorship of the US Department of Energy (DOE), Oak Ridge National Laboratory, Argonne National Laboratory, GE Nuclear Energy and several universities are performing research and development in the application of advances in control theory, software engineering, advanced computer architectures, artificial intelligence, and man-machine interface analysis to control system design. The target plant concept for the work described in this paper is the Power Reactor Inherently Safe Module reactor (PRISM), an advanced modular liquid metal reactor concept. This and other reactor designs which provide strong passive responses to operational upsets or accidents afford good opportunities to apply these advances in control technology. 18 refs., 5 figs.

  12. Demonstration of an Ultra-Short Channel Metal Monolith Catalytic Reactor for Trace Contaminant Control Applications

    NASA Technical Reports Server (NTRS)

    Perry, J. L; Carter, R. N.; Roychoudhury, S.

    1999-01-01

    The International Space Station (ISS) Trace Contaminant Control Subassembly (TCCS) design is based upon proven, highly reliable technology. However, because its core unit operations rely upon expendable activated charcoal and an indirectly heated high temperature catalyst, annual logistics mass, crew time, and power consumption requirements are significant. To address this situation, a unique catalytic reactor design has been developed which is suitable for retrofit into the TCCS's high temperature catalytic oxidizer (HTCO) assembly. The unique design, which employs a metallic, ultra-short channel length monolith (USCM) catalyst substrate, was tested in a flight-like TCCS HTCO assembly to investigate its performance characteristics. Test results indicate that retrofitting the TCCS with a USCM-based catalytic reactor is feasible and that it may provide significant reductions in logistics mass, crew time, and power consumption. Savings indicated by test results are up to 81% for annual logistics, 56% for crew time, and 77% for startup transient duration. In addition, its demonstrated ability to operate in a power saving mode provides up to a 43% savings in average power consumption. A summary of the USCM demonstration test objectives, approach, results, and specific benefits to the TCCS's process economics are presented,

  13. Startup and control of out-of-core thermionic space reactors

    NASA Astrophysics Data System (ADS)

    Houts, M. G.; Lanning, D. D.

    An analysis of out-of-core thermionic space reactor (OTR) startup and control has been performed. The reference ionic thermal reactor (ITR) chosen for this study is a 75 kWt version of the STAR-C (GA Technologies 1987). The applicability of point kinetics was first verified for the reference OTR system. Point kinetics applicability was verified for core length-to-diameter (L/D) ratios of two and four, and for both subcritical-to-critical and critical-to-supercritical transients. A coupled thermal/point kinetics code was then written, and OTR startup was analyzed. The analyses lead to several observations. First, point kinetics is applicable to the reference OTR for all transients considered. Second, to achieve a 900 second startup the reference OTR must operate at powers well above steady-state rated power during startup. Finally, the large thermal inertia of the radial reflector could be used to reduce radiator temperature during the first several hundred seconds of operation. Further research should be performed on transient heat pipe operation and on off-normal thermionic converter operation.

  14. Feasibility study of the University of Utah TRIGA reactor power upgrade in respect to control rod system

    NASA Astrophysics Data System (ADS)

    Cutic, Avdo

    The objectives of this thesis are twofold: to determine the highest achievable power levels of the current University of Utah TRIG Reactor (UUTR) core configuration with the existing three control rods, and to design the core for higher reactor power by optimizing the control rod worth. For the current core configuration, the maximum reactor power, eigenvalue keff, shutdown margin, and excess reactivity have been measured and calculated. These calculated estimates resulted from thermal power calibrations, and the control rod worth measurements at various power levels. The results were then used as a benchmark to verify the MCNP5 core simulations for the current core and then to design a core for higher reactor power. This study showed that the maximum achievable power with the current core configuration and control rod system is 150kW, which is 50kW higher than the licensed power of the UUTR. The maximum achievable UUTR core power with the existing fuel is determined by optimizing the core configuration and control rod worth, showing that a power upgrade of 500 kW is achievable. However, it requires a new control rod system consisting of a total of four control rods. The cost of such an upgrade is $115,000.

  15. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    NASA Astrophysics Data System (ADS)

    Winterberg, F.

    2016-01-01

    Einstein's general theory of relativity implies the existence of virtual negative masses in the rotational reference frame of an ultracentrifuge with the negative mass density of the same order of magnitude as the positive mass density of a neutron star. In an ultracentrifuge, the repulsive gravitational field of this negative mass can simulate the attractive positive mass of a mini-neutron star, and for this reason can radially confine a dense thermonuclear plasma placed inside the centrifuge, very much as the positive mass of a star confines its plasma by its own attractive gravitational field. If the centrifuge is placed in an externally magnetic field to act as the seed field of a magnetohydrodynamic generator, the configuration resembles a magnetar driven by the release of energy through nuclear fusion, accelerating the plasma to supersonic velocities, with the magnetic field produced by the thermomagnetic Nernst effect insulating the hot plasma from the cold wall of the centrifuge. Because of the supersonic flow and the high plasma density the configuration is stable.

  16. High energy components and collective modes in thermonuclear plasmas

    SciTech Connect

    Coppi, B.; Cowley, S.; Detragiache, P.; Kulsrud, R.; Pegoraro, F.

    1986-02-01

    The theory of a class of collective modes of a thermonuclear magnetically confined plasma, with frequencies in the range of the ion cyclotron frequency and of its harmonics, is presented. These modes can be excited by their resonant cyclotron interaction with a plasma component of relatively high energy particles characterized by a strongly anisotropic distribution in velocity space. Normal modes that are spatially localized by the inhomogeneity of the plasma density are found. This ensures that the energy gained by their resonant interaction is not convected away. The mode spatial localization can be significantly altered by the magnetic field inhomogeneity for a given class of plasma density profiles. Special attention is devoted to the case of a spin polarized plasma, where the charged products of fusion reactions are anisotropically distributed. We show that for the mode of polarization that enhances nuclear reaction rates the tritium will be rapidly depolarized to toroidal configurations with relatively mild gradients of the confining magnetic field. 18 refs., 9 figs.

  17. Evidence of Spreading Layer Emission in a Thermonuclear Superburst

    NASA Astrophysics Data System (ADS)

    Koljonen, K. I. I.; Kajava, J. J. E.; Kuulkers, E.

    2016-10-01

    When a neutron star (NS) accretes matter from a companion star in a low-mass X-ray binary, the accreted gas settles onto the stellar surface through a boundary/spreading layer. On rare occasions the accumulated gas undergoes a powerful thermonuclear superburst powered by carbon burning deep below the NS atmosphere. In this paper, we apply the non-negative matrix factorization spectral decomposition technique to show that the spectral variations during a superburst from 4U 1636-536 can be explained by two distinct components: (1) the superburst emission characterized by a variable temperature blackbody radiation component and (2) a quasi-Planckian component with a constant, ˜2.5 keV, temperature varying by a factor of ˜15 in flux. The spectrum of the quasi-Planckian component is identical in shape and characteristics to the frequency-resolved spectra observed in the accretion/persistent spectrum of NS low-mass X-ray binaries and agrees well with the predictions of the spreading layer model by Inogamov & Sunyaev. Our results provide yet more observational evidence that superbursts—and possibly also normal X-ray bursts—induce changes in the disc-star boundary.

  18. Evaluation of Miniaturized Infrared Sensors for Process Control of the Palladium Membrane Reactor

    SciTech Connect

    Lascola, R. J.; Howard, D. W.

    2005-07-31

    We have tested the suitability of a miniaturized infrared sensor for measurements of CO and H{sub 2}O in the inlet stream to the Palladium Membrane Reactor (PMR). We demonstrated that both analytes can be measured with absolute accuracies of 2-4% at the process inlet conditions of 120-140 C and approximately 1 atm of each gas. This accuracy must be improved to 1-1.5% for effective PMR process control. The use of a reference detector and independent temperature and pressure measurements to correct the raw signals will improve the accuracy to a level that will approach, if not meet, this goal. With appropriate bandpass filters, the infrared sensors may be used for other gas analysis applications.

  19. Fabrication of cermet bearings for the control system of a high temperature lithium cooled nuclear reactor

    NASA Technical Reports Server (NTRS)

    Yacobucci, H. G.; Heestand, R. L.; Kizer, D. E.

    1973-01-01

    The techniques used to fabricate cermet bearings for the fueled control drums of a liquid metal cooled reference-design reactor concept are presented. The bearings were designed for operation in lithium for as long as 5 years at temperatures to 1205 C. Two sets of bearings were fabricated from a hafnium carbide - 8-wt. % molybdenum - 2-wt. % niobium carbide cermet, and two sets were fabricated from a hafnium nitride - 10-wt. % tungsten cermet. Procedures were developed for synthesizing the material in high purity inert-atmosphere glove boxes to minimize oxygen content in order to enhance corrosion resistance. Techniques were developed for pressing cylindrical billets to conserve materials and to reduce machining requirements. Finishing was accomplished by a combination of diamond grinding, electrodischarge machining, and diamond lapping. Samples were characterized in respect to composition, impurity level, lattice parameter, microstructure and density.

  20. Aging assessment of the boiling-water reactor (BWR) standby liquid control system. Phase 1

    SciTech Connect

    Orton, R.D.; Johnson, A.B.; Buckley, G.D.; Larson, L.L.

    1992-10-01

    Pacific Northwest Laboratory conducted a Phase I aging assessment of the standby liquid control (SLC) system used in boiling-water reactors. The study was based on detailed reviews of SLC system component and operating experience information obtained from the Nuclear Plant Reliability Database System, the Nuclear Document System, Licensee Event Reports, and other databases. Sources dealing with sodium pentaborate, borates, boric acid, and the effects of environment and corrosion in the SLC system were reviewed to characterize chemical properties and corrosion characteristics of borated solutions. The leading aging degradation concern to date appears to be setpoint drift in relief valves, which has been discovered during routine surveillance and is thought to be caused by mechanical wear. Degradation was also observed in pump seals and internal valves. In general, however, the results of the Phase I study suggest that age-related degradation of SLC systems has not been serious.

  1. Aging assessment of the boiling-water reactor (BWR) standby liquid control system

    SciTech Connect

    Orton, R.D.; Johnson, A.B.; Buckley, G.D.; Larson, L.L.

    1992-10-01

    Pacific Northwest Laboratory conducted a Phase I aging assessment of the standby liquid control (SLC) system used in boiling-water reactors. The study was based on detailed reviews of SLC system component and operating experience information obtained from the Nuclear Plant Reliability Database System, the Nuclear Document System, Licensee Event Reports, and other databases. Sources dealing with sodium pentaborate, borates, boric acid, and the effects of environment and corrosion in the SLC system were reviewed to characterize chemical properties and corrosion characteristics of borated solutions. The leading aging degradation concern to date appears to be setpoint drift in relief valves, which has been discovered during routine surveillance and is thought to be caused by mechanical wear. Degradation was also observed in pump seals and internal valves. In general, however, the results of the Phase I study suggest that age-related degradation of SLC systems has not been serious.

  2. Integration of equalisation tanks within control strategies for anaerobic reactors. Validation based on ADM1 simulations.

    PubMed

    Alferes, J; García-Heras, J L; Roca, E; García, C; Irizar, I

    2008-01-01

    The combination of equalisation tanks and anaerobic digesters represents a typical design scenario within the treatment of industrial wastewaters. In this context, if the hydraulic capacity of the equalisation tanks is effectively handled, significant improvements in the performance of anaerobic digesters can be achieved in terms of process stability and biogas production. This paper presents a rule-based control strategy for anaerobic reactors with the objective of maximising in the long-term the net production of biogas. The control algorithm combines real-time information about the state of the anaerobic digester with on-line measurements about the wastewater volume of the equalisation tank in order to set permanently the appropriate production of biogas. Such a strategy guarantees a continuous influent flow so that emptying and overflowing episodes in the equalisation tank can be prevented. Aiming at a further full-scale implementation, only reliable and cost-effective on-line instrumentation has been considered within the control architecture. The performance of the proposed control approach has been validated for an anaerobic hybrid configuration (AHR) by simulation using the IWA ADM1 model. PMID:18401148

  3. Interim results of the study of control room crew staffing for advanced passive reactor plants

    SciTech Connect

    Hallbert, B.P.; Sebok, A.; Haugset, K.

    1996-03-01

    Differences in the ways in which vendors expect the operations staff to interact with advanced passive plants by vendors have led to a need for reconsideration of the minimum shift staffing requirements of licensed Reactor Operators and Senior Reactor Operators contained in current federal regulations (i.e., 10 CFR 50.54(m)). A research project is being carried out to evaluate the impact(s) of advanced passive plant design and staffing of control room crews on operator and team performance. The purpose of the project is to contribute to the understanding of potential safety issues and provide data to support the development of design review guidance. Two factors are being evaluated across a range of plant operating conditions: control room crew staffing; and characteristics of the operating facility itself, whether it employs conventional or advanced, passive features. This paper presents the results of the first phase of the study conducted at the Loviisa nuclear power station earlier this year. Loviisa served as the conventional plant in this study. Data collection from four crews were collected from a series of design basis scenarios, each crew serving in either a normal or minimum staffing configuration. Results of data analyses show that crews participating in the minimum shift staffing configuration experienced significantly higher workload, had lower situation awareness, demonstrated significantly less effective team performance, and performed more poorly as a crew than the crews participating in the normal shift staffing configuration. The baseline data on crew configurations from the conventional plant setting will be compared with similar data to be collected from the advanced plant setting, and a report prepared providing the results of the entire study.

  4. Helium-3 blankets for tritium breeding in fusion reactors

    NASA Technical Reports Server (NTRS)

    Steiner, Don; Embrechts, Mark; Varsamis, Georgios; Vesey, Roger; Gierszewski, Paul

    1988-01-01

    It is concluded that He-3 blankets offers considerable promise for tritium breeding in fusion reactors: good breeding potential, low operational risk, and attractive safety features. The availability of He-3 resources is the key issue for this concept. There is sufficient He-3 from decay of military stockpiles to meet the International Thermonuclear Experimental Reactor needs. Extraterrestrial sources of He-3 would be required for a fusion power economy.

  5. NEUTRONIC REACTOR

    DOEpatents

    Hurwitz, H. Jr.; Brooks, H.; Mannal, C.; Payne, J.H.; Luebke, E.A.

    1959-03-24

    A reactor of the heterogeneous, liquid cooled type is described. This reactor is comprised of a central region of a plurality of vertically disposed elongated tubes surrounded by a region of moderator material. The central region is comprised of a central core surrounded by a reflector region which is surrounded by a fast neutron absorber region, which in turn is surrounded by a slow neutron absorber region. Liquid sodium is used as the primary coolant and circulates through the core which contains the fuel elements. Control of the reactor is accomplished by varying the ability of the reflector region to reflect neutrons back into the core of the reactor. For this purpose the reflector is comprised of moderator and control elements having varying effects on reactivity, the control elements being arranged and actuated by groups to give regulation, shim, and safety control.

  6. Extraction of gadolinium from high flux isotope reactor control plates. [Alternative method

    SciTech Connect

    Kohring, M.W.

    1987-04-01

    Gadolinium-153 is an important radioisotope used in the diagnosis of various bone disorders. Recent medical and technical developments in the detection and cure of osteoporosis, a bone disease affecting an estimated 50 million people, have greatly increased the demand for this isotope. The Oak Ridge National Laboratory (ORNL) has produced /sup 153/Gd since 1980 primarily through the irradiation of a natural europium-oxide powder followed by the chemical separation of the gadolinium fraction from the europium material. Due to the higher demand for /sup 153/Gd, an alternative production method to supplement this process has been investigated. This process involves the extraction of gadolinium from the europium-bearing region of highly radioactive, spent control plates used at the High Flux Isotope Reactor (HFIR) with a subsequent re-irradiation of the extracted material for the production of the /sup 153/Gd. Based on the results of experimental and calculational analyses, up to 25 grams of valuable gadolinium (greater than or equal to60% enriched in /sup 152/Gd) resides in the europium-bearing region of the HFIR control components of which 70% is recoverable. At a specific activity yield of 40 curies of /sup 153/Gd for each gram of gadolinium re-irradiated, 700 one-curie sources can be produced from each control plate assayed.

  7. The Programmable Logic Controller and its application in nuclear reactor systems

    SciTech Connect

    Palomar, J.; Wyman, R.

    1993-09-01

    This document provides recommendations to guide reviewers in the application of Programmable Logic Controllers (PLCS) to the control, monitoring and protection of nuclear reactors. The first topics addressed are system-level design issues, specifically including safety. The document then discusses concerns about the PLC manufacturing organization and the protection system engineering organization. Supplementing this document are two appendices. Appendix A summarizes PLC characteristics. Specifically addressed are those characteristics that make the PLC more suitable for emergency shutdown systems than other electrical/electronic-based systems, as well as characteristics that improve reliability of a system. Also covered are PLC characteristics that may create an unsafe operating environment. Appendix B provides an overview of the use of programmable logic controllers in emergency shutdown systems. The intent is to familiarize the reader with the design, development, test, and maintenance phases of applying a PLC to an ESD system. Each phase is described in detail and information pertinent to the application of a PLC is pointed out.

  8. Theory of supercompression of vapor bubbles and nanoscale thermonuclear fusion

    SciTech Connect

    Nigmatulin, Robert I.; Akhatov, Iskander Sh.; Topolnikov, Andrey S.; Bolotnova, Raisa Kh.; Vakhitova, Nailya K.; Lahey, Richard T. Jr.; Taleyarkhan, Rusi P.

    2005-10-01

    This paper provides the theoretical basis for energetic vapor bubble implosions induced by a standing acoustic wave. Its primary goal is to describe, explain, and demonstrate the plausibility of the experimental observations by Taleyarkhan et al. [Science 295, 1868 (2002); Phys. Rev. E 69, 036109 (2004)] of thermonuclear fusion for imploding cavitation bubbles in chilled deuterated acetone. A detailed description and analysis of these data, including a resolution of the criticisms that have been raised, together with some preliminary HYDRO code simulations, has been given by Nigmatulin et al. [Vestnik ANRB (Ufa, Russia) 4, 3 (2002); J. Power Energy 218-A, 345 (2004)] and Lahey et al. [Adv. Heat Transfer (to be published)]. In this paper a hydrodynamic shock (i.e., HYDRO) code model of the spherically symmetric motion for a vapor bubble in an acoustically forced liquid is presented. This model describes cavitation bubble cluster growth during the expansion period, followed by a violent implosion during the compression period of the acoustic cycle. There are two stages of the bubble dynamics process. The first, low Mach number stage, comprises almost all the time of the acoustic cycle. During this stage, the radial velocities are much less than the sound speeds in the vapor and liquid, the vapor pressure is very close to uniform, and the liquid is practically incompressible. This process is characterized by the inertia of the liquid, heat conduction, and the evaporation or condensation of the vapor. The second, very short, high Mach number stage is when the radial velocities are the same order, or higher, than the sound speeds in the vapor and liquid. In this stage high temperatures, pressures, and densities of the vapor and liquid take place. The model presented herein has realistic equations of state for the compressible liquid and vapor phases, and accounts for nonequilibrium evaporation/condensation kinetics at the liquid/vapor interface. There are interacting

  9. Theory of supercompression of vapor bubbles and nanoscale thermonuclear fusion

    NASA Astrophysics Data System (ADS)

    Nigmatulin, Robert I.; Akhatov, Iskander Sh.; Topolnikov, Andrey S.; Bolotnova, Raisa Kh.; Vakhitova, Nailya K.; Lahey, Richard T.; Taleyarkhan, Rusi P.

    2005-10-01

    This paper provides the theoretical basis for energetic vapor bubble implosions induced by a standing acoustic wave. Its primary goal is to describe, explain, and demonstrate the plausibility of the experimental observations by Taleyarkhan et al. [Science 295, 1868 (2002); Phys. Rev. E 69, 036109 (2004)] of thermonuclear fusion for imploding cavitation bubbles in chilled deuterated acetone. A detailed description and analysis of these data, including a resolution of the criticisms that have been raised, together with some preliminary HYDRO code simulations, has been given by Nigmatulin et al. [Vestnik ANRB (Ufa, Russia) 4, 3 (2002); J. Power Energy 218-A, 345 (2004)] and Lahey et al. [Adv. Heat Transfer (to be published)]. In this paper a hydrodynamic shock (i.e., HYDRO) code model of the spherically symmetric motion for a vapor bubble in an acoustically forced liquid is presented. This model describes cavitation bubble cluster growth during the expansion period, followed by a violent implosion during the compression period of the acoustic cycle. There are two stages of the bubble dynamics process. The first, low Mach number stage, comprises almost all the time of the acoustic cycle. During this stage, the radial velocities are much less than the sound speeds in the vapor and liquid, the vapor pressure is very close to uniform, and the liquid is practically incompressible. This process is characterized by the inertia of the liquid, heat conduction, and the evaporation or condensation of the vapor. The second, very short, high Mach number stage is when the radial velocities are the same order, or higher, than the sound speeds in the vapor and liquid. In this stage high temperatures, pressures, and densities of the vapor and liquid take place. The model presented herein has realistic equations of state for the compressible liquid and vapor phases, and accounts for nonequilibrium evaporation/condensation kinetics at the liquid/vapor interface. There are interacting

  10. Treatment of Spacecraft Wastewater Using a Hollow Fiber Membrane Biofilm Redox Control Reactor

    NASA Technical Reports Server (NTRS)

    Smith, Daniel P.

    2003-01-01

    The purpose of this project was to develop and evaluate design concepts for biological treatment reactors for the purification of spacecraft wastewater prior to reverse osmosis treatment. The motivating factor is that wastewater recovery represents the greatest single potential reduction in the resupply requirements for crewed space missions. Spacecraft wastewater composition was estimated from the characteristics of the three major component streams: urine/flush water, hygiene water, and atmospheric condensate. The key characteristics of composite spacecraft wastewater are a theoretical oxygen demand of 4519 mg/L, of which 65% is nitrogenous oxygen demand, in a volume of 11.5 liter/crew-day. The organic carbon to nitrogen ratio of composite wastewater is 0.86. Urine represents 93% of nitrogen and 49% of the organic carbon in the composite wastestream. Various bioreaction scenarios were evaluated to project stoichiometric oxygen demands and the ability of wastewater carbon to support denitrification. Ammonia nitrification to the nitrite oxidation state reduced the oxygen requirement and enabled wastewater carbon to provide nearly complete denitrification. A conceptual bioreactor design was established using hollow fiber membranes for bubbleless oxygen transfer in a gravity-free environment, in close spatial juxtaposition to a second interspaced hollow fiber array for supplying molecular hydrogen. Highly versatile redox control and an enhanced ability to engineer syntrophic associations are stated advantages. A prototype reactor was constructed using a microporous hollow fiber membrane module for aeration. Maintaining inlet gas pressure within 0.25 psi of the external water pressure resulted in bubble free operation with no water ingress into hollow fiber lumens. Recommendations include the design and operational testing of hollow fiber bioreactors using: 1) Partial nitrification/nitrite predenitrification; 2) Limited aeration for simultaneous nitrification

  11. Prospects for toroidal fusion reactors

    SciTech Connect

    Sheffield, J.; Galambos, J.D.

    1994-06-01

    Work on the International Thermonuclear Experimental Reactor (ITER) tokamak has refined understanding of the realities of a deuterium-tritium (D-T) burning magnetic fusion reactor. An ITER-like tokamak reactor using ITER costs and performance would lead to a cost of electricity (COE) of about 130 mills/kWh. Advanced tokamak physics to be tested in the Toroidal Physics Experiment (TPX), coupled with moderate components in engineering, technology, and unit costs, should lead to a COE comparable with best existing fission systems around 60 mills/kWh. However, a larger unit size, {approximately}2000 MW(e), is favored for the fusion system. Alternative toroidal configurations to the conventional tokamak, such as the stellarator, reversed-field pinch, and field-reversed configuration, offer some potential advantage, but are less well developed, and have their own challenges.

  12. Features of temperature control of fuel element cladding for pressurized water nuclear reactor ``WWER-1000'' while simulating reactor accidents

    NASA Astrophysics Data System (ADS)

    Zaytsev, P. A.; Priymak, S. V.; Usachev, V. B.; Oleynikov, P. P.; Soldatkin, D. M.

    2013-09-01

    During the experiments simulating NPR (nuclear power reactor) accidents with a coolant loss fuel elements behavior in a steam-hydrogen medium was studied at the temperature changed with the rate from 1 to 100K/s within the range of 300÷1500 °C. Indications of the thermocouples fixed on the cladding notably differ from real values of the cladding temperatures in the area of measuring junction due to thermal resistance influence of the transition zones "cladding-junction" and "junction-coolant". The estimating method of a measurement error was considered which can provide adequate accounting of the influence factors. The method is based on thermal probing of a thermocouple by electric current flashing through thermoelements under the coolant presence or absence, a response time registration and processing, calculation of thermal inertia value for a thermocouple junction. A formula was derived for calculation of methodical error under stationary mode and within the stage of linear increase in temperature, which will determine the conditions for the cladding depressurization. Some variants of the formula application were considered, and the values of methodical errors were established which reached ˜5% of maximum value by the final moment of the stage of linear increase in the temperature.

  13. NEUTRONIC REACTOR MANIPULATING DEVICE

    DOEpatents

    Ohlinger, L.A.

    1962-08-01

    A cable connecting a control rod in a reactor with a motor outside the reactor for moving the rod, and a helical conduit in the reactor wall, through which the cable passes are described. The helical shape of the conduit prevents the escape of certain harmful radiations from the reactor. (AEC)

  14. Parameterized data-driven fuzzy model based optimal control of a semi-batch reactor.

    PubMed

    Kamesh, Reddi; Rani, K Yamuna

    2016-09-01

    A parameterized data-driven fuzzy (PDDF) model structure is proposed for semi-batch processes, and its application for optimal control is illustrated. The orthonormally parameterized input trajectories, initial states and process parameters are the inputs to the model, which predicts the output trajectories in terms of Fourier coefficients. Fuzzy rules are formulated based on the signs of a linear data-driven model, while the defuzzification step incorporates a linear regression model to shift the domain from input to output domain. The fuzzy model is employed to formulate an optimal control problem for single rate as well as multi-rate systems. Simulation study on a multivariable semi-batch reactor system reveals that the proposed PDDF modeling approach is capable of capturing the nonlinear and time-varying behavior inherent in the semi-batch system fairly accurately, and the results of operating trajectory optimization using the proposed model are found to be comparable to the results obtained using the exact first principles model, and are also found to be comparable to or better than parameterized data-driven artificial neural network model based optimization results.

  15. Aging mechanisms in the Westinghouse PWR (Pressurized Water Reactor) Control Rod Drive system

    SciTech Connect

    Gunther, W.; Sullivan, K.

    1991-01-01

    An aging assessment of the Westinghouse Pressurized Water Reactor (PWR) Control Rod System (CRD) has been completed as part of the US NRC's Nuclear Plant Aging Research, (NPAR) Program. This study examined the design, construction, maintenance, and operation of the system to determine its potential for degradation as the plant ages. Selected results from this study are presented in this paper. The operating experience data were evaluated to identify the predominant failure modes, causes, and effects. From our evaluation of the data, coupled with an assessment of the materials of construction and the operating environment, we conclude that the Westinghouse CRD system is subject to degradation which, if unchecked, could affect its safety function as a plant ages. Ways to detect and mitigate the effects of aging are included in this paper. The current maintenance for the control rod drive system at fifteen Westinghouse PWRs was obtained through a survey conducted in cooperation with EPRI and NUMARC. The results of the survey indicate that some plants have modified the system, replaced components, or expanded preventive maintenance. Several of these activities have effectively addressed the aging issue. 2 refs., 2 figs., 2 tabs.

  16. (Fusion materials R D programs of the International Thermonuclear Experimental Reactor)

    SciTech Connect

    Reuther, T.C.

    1990-10-12

    The objective of this travel was to advance provisional planning of an activity to coordinate research and development (R D) activities on fusion materials among the existing fusion materials R D programs of the ITER parties. This objective was accomplished in discussions with the Executive Committee for the IEA Implementing Agreement on Fusion Materials in Karlsruhe, Germany, and with the ITER management and staff of Garching, Germany. The IEA Executive Committee deferred substantive consideration of the topic at the insistence of the Ex-Officio member from European Community (EC), Brussels. Discussions with ITER management and staff were positive. It was noted the the draft ITER Long-Term Technology Research and Development Plan contains recommendations for major program effort in materials R D and includes recommendations for coordination among the existing programs of the parties to meet those materials R D needs. ITER management discussions were in the context that decisions on specific activities for the ITER engineering design activity (EDA) must await formal action by the parties on the ITER EDA.

  17. Investigation of high purity beryllium for the International Thermonuclear Experimental Reactor (ITER), Task 002. Final report

    SciTech Connect

    Vagin, S.P.

    1995-05-01

    The report includes a description of experimental abilities of Solid Structure Research Laboratory of IAE NNC RK, a results of microstructural characterization of A-4 grade polycrystal Beryllium produced at the Ulba metal plant and a technical project-for irradiation experiments. Technical project contains a detailed description of five proposed experiments, clearing behavior of Beryllium materials under the influence of irradiation, temperature, helium and hydrogen accumulation. Complex irradiation jobs, microstructural investigations and mechanical tests are planned in the framework of these experiments.

  18. ITER vacuum vessel fabrication plan and cost study (D 68) for the international thermonuclear experimental reactor

    SciTech Connect

    1995-01-01

    ITER Task No. 8, Vacuum Vessel Fabrication Plan and Cost Study (D68), was initiated to assess ITER vacuum vessel fabrication, assembly, and cost. The industrial team of Raytheon Engineers & Constructors and Chicago Bridge & Iron (Raytheon/CB&I) reviewed the current vessel basis and prepared a manufacturing plan, assembly plan, and cost estimate commensurate with the present design. The guidance for the Raytheon/CB&I assessment activities was prepared by the ITER Garching Work Site. This guidance provided in the form of work descriptions, sketches, drawings, and costing guidelines for each of the presently identified vacuum vessel Work Breakdown Structure (WBS) elements was compiled in ITER Garching Joint Work Site Memo (Draft No. 9 - G 15 MD 01 94-17-05 W 1). A copy of this document is provided as Appendix 1 to this report. Additional information and clarifications required for the Raytheon/CB&I assessments were coordinated through the US Home Team (USHT) and its technical representative. Design details considered essential to the Task 8 assessments but not available from the ITER Joint Central Team (JCT) were generated by Raytheon/CB&I and documented accordingly.

  19. Fusion power production in International Thermonuclear Experimental Reactor baseline H-mode scenarios

    SciTech Connect

    Rafiq, T.; Kritz, A. H.; Kessel, C. E.; Pankin, A. Y.

    2015-04-15

    Self-consistent simulations of 15 MA ITER H-mode DT scenarios, from ramp-up through flat-top, are carried out. Electron and ion temperatures, toroidal angular frequency, and currents are evolved, in simulations carried out using the predictive TRANSPort and integrated modeling code starting with initial profiles and equilibria obtained from tokamak simulation code studies. Studies are carried out examining the dependence and sensitivity of fusion power production on electron density, argon impurity concentration, choice of radio frequency heating, pedestal temperature without and with E × B flow shear effects included, and the degree of plasma rotation. The goal of these whole-device ITER simulations is to identify dependencies that might impact ITER fusion performance.

  20. Physics modeling support for the International Thermonuclear Experimental Reactor: Final report

    SciTech Connect

    Not Available

    1988-09-30

    There are two major sections to this report. The first section of the report is an executive summary of the work done this year. For each task, the major results are condensed for the reader's convenience. The major result of each memo, report or presentation is summarized briefly in this section. The second section of the report is a collection of appendices containing reports, memos, and presentations written this year. Here, the interested reader can investigate any topic discussed in the summary in more detail. The documentation is presented in chronological order, and we would like to note that the content of later documents may supercede that of earlier ones. The summaries are divided into sections, corresponding to the tasks outlined in the original proposal for the work. These sections are: MUMAK code development and application; Alfven wave stability problem; TETRA systems code development and application; lower hybrid heating and current drive; and advanced blanket modeling.

  1. Model coil for the international thermonuclear experimental reactor (ITER) magnet systems

    NASA Astrophysics Data System (ADS)

    Okuno, K.

    1994-07-01

    The model coil program for the ITER EDA includes the manufacture and testing of one Central Solenoid (CS) model coil and one Toroidal Field (TF) model coil, and test facility preparations. The CS model coil has an inner diameter of 1.6 m and produces a full field of 13 T. The TF model coil is race-track shaped with an outer dimension of 3 m x 4 m. It will be tested in conjunction with an LCT coil to simulate mechanical load conditions. Different kinds of conductors can be tested as inserts to be placed in the bore of the CS model coil. Two facilities at JAERI and KfK can provide ITER-relevant conditions for testing the model coils and inserts. The model coil program will validate the ITER magnet design and the manufacturing feasibility.

  2. Closed-loop control of ammonium concentration in nitritation: convenient for reactor operation but also for modeling.

    PubMed

    Jemaat, Zulkifly; Bartrolí, Albert; Isanta, Eduardo; Carrera, Julián; Suárez-Ojeda, María Eugenia; Pérez, Julio

    2013-01-01

    A mathematical biofilm model was developed to describe nitritation in aerobic granular reactor operating in continuous mode. The model includes the automatic closed-loop control of ammonium concentration in the effluent. This is integrated in a ratio control strategy to maintain the proportion between the dissolved oxygen (DO) and the total ammonia nitrogen (TAN) concentrations in the reactor effluent at a desired value. The model was validated with a large set of experimental results previously reported in the literature. The model was used to study the effect of DO and TAN setpoints on the achievement of full nitritation, as well as to establish the appropriate required range of the DO/TAN concentration ratio to be applied. Nitritation at 20 °C was tested experimentally and simulated with the model. Additionally, the importance of controlling the TAN concentration was highlighted with different scenarios, in which periodic disturbances were applied mimicking a poor control situation.

  3. Vulnerability assessment of a space based weapon platform electronic system exposed to a thermonuclear weapon detonation

    NASA Astrophysics Data System (ADS)

    Perez, C. L.; Johnson, J. O.

    Rapidly changing world events, the increased number of nations with inter-continental ballistic missile capability, and the proliferation of nuclear weapon technology will increase the number of nuclear threats facing the world today. Monitoring these nation's activities and providing an early warning and/or intercept system via reconnaissance and surveillance satellites and space based weapon platforms is a viable deterrent against a surprise nuclear attack. However, the deployment of satellite and weapon platform assets in space will subject the sensitive electronic equipment to a variety of natural and man-made radiation environments. These include Van Allen Belt protons and electrons; galactic and solar flare protons; and neutrons, gamma rays, and x-rays from intentionally detonated fission and fusion weapons. In this paper, the MASH vl.0 code system is used to estimate the dose to the critical electronics components of an idealized space based weapon platform from neutron and gamma-ray radiation emitted from a thermonuclear weapon detonation in space. Fluence and dose assessments were performed for the platform fully loaded, and in several stages representing limited engagement scenarios. The results indicate vulnerabilities to the Command, Control, and Communication bay instruments from radiation damage for a nuclear weapon detonation for certain source/platform orientations. The distance at which damage occurs will depend on the weapon yield (n,(gamma)/kiloton) and size (kilotons).

  4. Light Water Reactor Sustainability Program Advanced Instrumentation, Information, and Control Systems Technologies Technical Program Plan for 2013

    SciTech Connect

    Hallbert, Bruce; Thomas, Ken

    2014-09-01

    Reliable instrumentation, information, and control (II&C) systems technologies are essential to ensuring safe and efficient operation of the U.S. light water reactor (LWR) fleet. These technologies affect every aspect of nuclear power plant (NPP) and balance-of-plant operations. In 1997, the National Research Council conducted a study concerning the challenges involved in modernization of digital instrumentation and control systems in NPPs. Their findings identified the need for new II&C technology integration.

  5. NUCLEAR REACTOR

    DOEpatents

    Miller, H.I.; Smith, R.C.

    1958-01-21

    This patent relates to nuclear reactors of the type which use a liquid fuel, such as a solution of uranyl sulfate in ordinary water which acts as the moderator. The reactor is comprised of a spherical vessel having a diameter of about 12 inches substantially surrounded by a reflector of beryllium oxide. Conventionnl control rods and safety rods are operated in slots in the reflector outside the vessel to control the operation of the reactor. An additional means for increasing the safety factor of the reactor by raising the ratio of delayed neutrons to prompt neutrons, is provided and consists of a soluble sulfate salt of beryllium dissolved in the liquid fuel in the proper proportion to obtain the result desired.

  6. The Nova Outburst: Thermonuclear Runaways on Degenerated Dwarfs

    SciTech Connect

    Starrfield, S.; Truran, J.W.; Sparks, W.M.

    1999-07-08

    Observational and theoretical studies of the outbursts of classical novae have provided critical insights into a broad range of astrophysical phenomena. Thermonuclear runaways (TNRs) in accreted hydrogen-rich envelopes on the white dwarf (WD) components of close binary systems constitute not only the outburst mechanism for a classical nova explosion, but also the recurrent novae and a fraction of the symbiotic novae explosions. Studies of the general characteristics of these explosions, both in our own galaxy and in neighboring galaxies of varying metallicity, can teach us about binary stellar evolution, while studies of the evolution of nova binary systems can constrain models for the (as yet unidentified) progenitors of Type Ia supernovae. Further, the empirical relation between the peak luminosity of a nova and the rate of decline, which presents a challenge to theoretical models, allows novae to be utilized as standard candles for distance determinations out to the Virgo Cluster. E xtensive studies of novae with IUE and the resulting abundance determinations have revealed the existence of oxygen-neon white dwarfs in some systems. The high levels of enrichment of novae ejecta in elements ranging from carbon to sulfur confirm that there is significant dredge-up of matter from the core of the underlying white dwarf and enable novae to contribute to the chemical enrichment of the interstellar medium. Observations of the epoch of dust formation in the expanding shells of novae allow important constraints to be placed on the dust formation process and confirm that graphite, SiC, and SiO{sub 2} grains are formed by the outburst. It is possible that grains from novae were injected into the pre-solar nebula and can be identified with some of the pre-solar grains or ''stardust'' found in meteorites. Finally, g-ray observations during the first several years of their outburst, using the next generation of satellite observatories, could confirm

  7. Nitrogen Removal over Nitrite by Aeration Control in Aerobic Granular Sludge Sequencing Batch Reactors

    PubMed Central

    Lochmatter, Samuel; Maillard, Julien; Holliger, Christof

    2014-01-01

    This study investigated the potential of aeration control for the achievement of N-removal over nitrite with aerobic granular sludge in sequencing batch reactors. N-removal over nitrite requires less COD, which is particularly interesting if COD is the limiting parameter for nutrient removal. The nutrient removal performances for COD, N and P have been analyzed as well as the concentration of nitrite-oxidizing bacteria in the granular sludge. Aeration phase length control combined with intermittent aeration or alternate high-low DO, has proven to be an efficient way to reduce the nitrite-oxidizing bacteria population and hence achieve N-removal over nitrite. N-removal efficiencies of up to 95% were achieved for an influent wastewater with COD:N:P ratios of 20:2.5:1. The total N-removal rate was 0.18 kgN·m−3·d−1. With N-removal over nitrate the N-removal was only 74%. At 20 °C, the nitrite-oxidizing bacteria concentration decreased by over 95% in 60 days and it was possible to switch from N-removal over nitrite to N-removal over nitrate and back again. At 15 °C, the nitrite-oxidizing bacteria concentration decreased too but less, and nitrite oxidation could not be completely suppressed. However, the combination of aeration phase length control and high-low DO was also at 15 °C successful to maintain the nitrite pathway despite the fact that the maximum growth rate of nitrite-oxidizing bacteria at temperatures below 20 °C is in general higher than the one of ammonium-oxidizing bacteria. PMID:25006970

  8. Conceptual design of Fusion Experimental Reactor

    NASA Astrophysics Data System (ADS)

    Seki, Yasushi; Takatsu, Hideyuki; Iida, Hiromasa

    1991-08-01

    Safety analysis and evaluation have been made for the FER (Fusion Experimental Reactor) as well as for the ITER (International Thermonuclear Experimental Reactor) which are basically the same in terms of safety. This report describes the results obtained in fiscal years 1988 - 1990, in addition to a summary of the results obtained prior to 1988. The report shows the philosophy of the safety design, safety analysis and evaluation for each of the operation conditions, namely, normal operation, repair and maintenance, and accident. Considerations for safety regulations and standards are also added.

  9. Disposal Of Irradiated Cadmium Control Rods From The Plumbrook Reactor Facility

    SciTech Connect

    Posivak, E.J.; Berger, S.R.; Freitag, A.A.

    2008-07-01

    Innovative mixed waste disposition from NASA's Plum Brook Reactor Facility was accomplished without costly repackaging. Irradiated characteristic hardware with contact dose rates as high as 8 Sv/hr was packaged in a HDPE overpack and stored in a Secure Environmental Container during earlier decommissioning efforts, awaiting identification of a suitable pathway. WMG obtained regulatory concurrence that the existing overpack would serve as the macro-encapsulant per 40CFR268.45 Table 1.C. The overpack vent was disabled and the overpack was placed in a stainless steel liner to satisfy overburden slumping requirements. The liner was sealed and placed in shielded shoring for transport to the disposal site in a US DOT Type A cask. Disposition via this innovative method avoided cost, risk, and dose associated with repackaging the high dose irradiated characteristic hardware. In conclusion: WMG accomplished what others said could not be done. Large D and D contractors advised NASA that the cadmium control rods could only be shipped to the proposed Yucca mountain repository. NASA management challenged MOTA to find a more realistic alternative. NASA and MOTA turned to WMG to develop a methodology to disposition the 'hot and nasty' waste that presumably had no path forward. Although WMG lead a team that accomplished the 'impossible', the project could not have been completed with out the patient, supportive management by DOE-EM, NASA, and MOTA. (authors)

  10. Gas cooled fast reactor control rod drive mechanism deceleration unit. Test program

    SciTech Connect

    Wagner, T.H.

    1981-10-01

    This report presents the results of the airtesting portion of the proof-of-principle testing of a Control Rod Scram Deceleration Device developed for use in the Gas Cooled Fast Reactor (GCFR). The device utilizes a grooved flywheel to decelerate the translating assembly (T/A). Two cam followers on the translating assembly travel in the flywheel grooves and transfer the energy of the T/A to the flywheel. The grooves in the flywheel are straight for most of the flywheel length. Near the bottom of the T/A stroke the grooves are spiraled in a decreasing slope helix so that the cam followers accelerate the flywheel as they transfer the energy of the falling T/A. To expedite proof-of-principle testing, some of the materials used in the fabrication of certain test article components were not prototypic. With these exceptions the concept appears to be acceptable. The initial test of 300 scrams was completed with only one failure and the failure was that of a non-prototypic cam follower outer sleeve material.

  11. Startup and control of out-of-core thermionic space reactors

    NASA Astrophysics Data System (ADS)

    Houts, Michael G.; Lanning, Davic D.

    1992-01-01

    An analysis of out-of-core thermionic space reactor (OTR) startup and control has been performed. The reference OTR chosen for this study is a 75 kWt version of the STAR-C (GA Technologies 1987). The applicability of point kinetics was first verified for the reference OTR system. Point kinetics applicability was verified for core length-to-diameter (L/D) ratios of two and four, and for both subcritical-to-critical and critical-to-supercritical transients. A coupled thermal/point kinetics code was then written, and OTR startup was analyzed. The analyses lead to several observations. First, point kinetics is applicable to the reference OTR for all transients considered. Second, to achieve a 900-s startup the reference OTR must operate at powers well above steady-state rated power during startup. Finally, the large thermal inertia of the radial reflector could be used to reduce radiator temperature during the first several hundred seconds of operation. Further research should be performed on transient heat pipe operation and on off-normal thermionic converter operation.

  12. Underground nuclear power station using self-regulating heat-pipe controlled reactors

    DOEpatents

    Hampel, Viktor E.

    1989-01-01

    A nuclear reactor for generating electricity is disposed underground at the bottom of a vertical hole that can be drilled using conventional drilling technology. The primary coolant of the reactor core is the working fluid in a plurality of thermodynamically coupled heat pipes emplaced in the hole between the heat source at the bottom of the hole and heat exchange means near the surface of the earth. Additionally, the primary coolant (consisting of the working flud in the heat pipes in the reactor core) moderates neutrons and regulates their reactivity, thus keeping the power of the reactor substantially constant. At the end of its useful life, the reactor core may be abandoned in place. Isolation from the atmosphere in case of accident or for abandonment is provided by the operation of explosive closures and mechanical valves emplaced along the hole. This invention combines technology developed and tested for small, highly efficient, space-based nuclear electric power plants with the technology of fast-acting closure mechanisms developed and used for underground testing of nuclear weapons. This invention provides a nuclear power installation which is safe from the worst conceivable reactor accident, namely, the explosion of a nuclear weapon near the ground surface of a nuclear power reactor.

  13. An underground nuclear power station using self-regulating heat-pipe controlled reactors

    DOEpatents

    Hampel, V.E.

    1988-05-17

    A nuclear reactor for generating electricity is disposed underground at the bottom of a vertical hole that can be drilled using conventional drilling technology. The primary coolant of the reactor core is the working fluid in a plurality of thermodynamically coupled heat pipes emplaced in the hole between the heat source at the bottom of the hole and heat exchange means near the surface of the earth. Additionally, the primary coolant (consisting of the working fluid in the heat pipes in the reactor core) moderates neutrons and regulates their reactivity, thus keeping the power of the reactor substantially constant. At the end of its useful life, the reactor core may be abandoned in place. Isolation from the atmosphere in case of accident or for abandonment is provided by the operation of explosive closures and mechanical valves emplaced along the hole. This invention combines technology developed and tested for small, highly efficient, space-based nuclear electric power plants with the technology of fast- acting closure mechanisms developed and used for underground testing of nuclear weapons. This invention provides a nuclear power installation which is safe from the worst conceivable reactor accident, namely, the explosion of a nuclear weapon near the ground surface of a nuclear power reactor. 5 figs.

  14. On the implementation of a chain nuclear reaction of thermonuclear fusion on the basis of the p+{sup 11}B process

    SciTech Connect

    Belyaev, V. S.; Krainov, V. P.; Zagreev, B. V.; Matafonov, A. P.

    2015-07-15

    Various theoretical and experimental schemes for implementing a thermonuclear reactor on the basis of the p+{sup 11}B reaction are considered. They include beam collisions, fusion in degenerate plasmas, ignition upon plasma acceleration by ponderomotive forces, and the irradiation of a solid-state target from {sup 11}B with a proton beam under conditions of a Coulomb explosion of hydrogen microdrops. The possibility of employing ultra-short high-intensity laser pulses to initiate the p+{sup 11}B reaction under conditions far from thermodynamic equilibrium is discussed. This and some other weakly radioactive thermonuclear reactions are promising owing to their ecological cleanness—there are virtually no neutrons among fusion products. Nuclear reactions that follow the p+{sup 11}B reaction may generate high-energy protons, sustaining a chain reaction, and this is an advantage of the p+{sup 11}B option. The approach used also makes it possible to study nuclear reactions under conditions close to those in the early Universe or in the interior of stars.

  15. Multilayer mirror based monitors for impurity controls in large fusion reactor type devices

    SciTech Connect

    Regan, S.P.; May, M.J.; Soukhanovskii, V.; Finkenthal, M.; Moos, H.W.

    1995-12-31

    Multilayer Mirror (MLM) based monitors are compact, high throughput diagnostics capable of extracting XUV emissions (the wavelength range including the soft-x-ray and the extreme ultraviolet, 10 {angstrom} to 304 {angstrom}) of impurities from the harsh environment of large fusion reactor type devices. For several years the Plasma Spectroscopy Group at Johns Hopkins University has investigated the application of MLM based XUV spectroscopic diagnostics for magnetically confined fusion plasmas. MLM based monitors have been constructed for and extensively used on DIII-D, Alcator C-mod, TEXT, Phaedrus-T, and CDX-U tokamaks to study the impurity behavior of elements ranging from He to Mo. On ITER MLM based devices would be used to monitor the spectral line emissions from Li I-like to F I-like charge states of Fe, Cr, and Ni, as well as extractors for the bands of emissions from high Z elements such as Mo or W for impurity controls of the fusion plasma. In addition to monitoring the impurity emissions from the main plasma, MLM based devices can also be adapted for radiation measurements of low Z elements in the divertor. The concepts and designs of these MLM based monitors for impurity controls in ITER will be presented. The results of neutron irradiation experiments of the MLMs performed in the Los Alamos Spallation Radiation Effects Facility (LASREF) at the Los Alamos National Laboratory will also be discussed. These preliminary neutron exposure studies show that the dispersive and reflective qualities of the MLMs were not affected in a significant manner.

  16. Control of electromagnetic edge effects in electrically-small rectangular plasma reactors

    SciTech Connect

    Trampel, Christopher P.; Stieler, Daniel S.

    2012-09-15

    Electromagnetic fields supported by rectangular reactors for plasma enhanced chemical vapor deposition are studied theoretically. Expressions for the fields in an electrically-small rectangular reactor with plasma in the chamber are derived. Modal field decompositions are employed under the homogeneous plasma slab approximation. The amplitude of each mode is determined analytically. It is shown that the field can be represented by the standing wave, evanescent waves tied to the edges, and an evanescent wave tied to the corners of the reactor. The impact of boundary conditions at the plasma edge on nonuniformity is quantified. Uniformity may be improved by placing a lossy magnetic layer on the reactor sidewalls. It is demonstrated that nonuniformity is a decreasing function of layer thickness.

  17. NEUTRONIC REACTORS

    DOEpatents

    Anderson, H.L.

    1958-10-01

    The design of control rods for nuclear reactors are described. In this design the control rod consists essentially of an elongated member constructed in part of a neutron absorbing material and having tube means extending therethrough for conducting a liquid to cool the rod when in use.

  18. Adaptive control of a packedbed reactor for the partial oxidation of n-butane to maleic anhydride; I. unsteady-state model and dynamics of the reactor

    SciTech Connect

    Not Available

    1984-01-01

    A nonadiabatic, fixed-bed catalytic reactor is analyzed on the basis of data for the highly exothermic partial oxidation of n-butane to maleic anhydride, in order to study multivariable adaptive control. The nonlinear partial differential equations describing the axial and radial gradients of concentration and temperature are converted into a set of nonlinear, ordinary differential and algebraic equations using orthogonal collocation, preserving the nonlinearity of the reaction term. These equations describe satisfactorily the steady state and dynamic behavior. This two-dimensional model enables the relationship between the time and temperature of reaction, and between the concentration of maleic anhydride and the hot-spot temperature to be expressed adequately by seconddegree, low-order transfer functions. This technique is applicable for any process of reaction in a packed bed.

  19. Particle formation and its control in dual frequency plasma etching reactors

    SciTech Connect

    Kim, Munsu; Cheong, Hee-Woon; Whang, Ki-Woong

    2015-07-15

    The behavior of a particle cloud in plasma etching reactors at the moment when radio frequency (RF) power changes, that is, turning off and transition steps, was observed using the laser-light-scattering method. Two types of reactors, dual-frequency capacitively coupled plasma (CCP) and the hybrid CCP/inductively coupled plasma (ICP), were set up for experiments. In the hybrid CCP/ICP reactor (hereafter ICP reactor), the position and shape of the cloud were strongly dependent on the RF frequency. The particle cloud becomes larger and approaches the electrode as the RF frequency increases. By turning the lower frequency power off later with a small delay time, the particle cloud is made to move away from the electrode. Maintaining lower frequency RF power only was also helpful to reduce the particle cloud size during this transition step. In the ICP reactor, a sufficient bias power is necessary to make a particle trap appear. A similar particle cloud to that in the CCP reactor was observed around the sheath region of the lower electrode. The authors can also use the low-frequency effect to move the particle cloud away from the substrate holder if two or more bias powers are applied to the substrate holder. The dependence of the particle behavior on the RF frequencies suggests that choosing the proper frequency at the right moment during RF power changes can reduce particle contamination effectively.

  20. Theoretical z -pinch scaling relations for thermonuclear-fusion experiments.

    PubMed

    Stygar, W A; Cuneo, M E; Vesey, R A; Ives, H C; Mazarakis, M G; Chandler, G A; Fehl, D L; Leeper, R J; Matzen, M K; McDaniel, D H; McGurn, J S; McKenney, J L; Muron, D J; Olson, C L; Porter, J L; Ramirez, J J; Seamen, J F; Speas, C S; Spielman, R B; Struve, K W; Torres, J A; Waisman, E M; Wagoner, T C; Gilliland, T L

    2005-08-01

    implosion time tau(i). For an accelerator coupled to a double-pinch-driven hohlraum that drives the implosion of an ICF fuel capsule, we find that the accelerator power and energy required to achieve high-yield fusion scale as tau(i)0.36 and tau(i)1.36, respectively. Thus the accelerator requirements decrease as the implosion time is decreased. However, the x-ray-power and thermonuclear-yield efficiencies of such a coupled system increase with tau(i). We also find that increasing the anode-cathode gap of the pinch from 2 to 4 mm increases the requisite values of P(a) and E(a) by as much as a factor of 2.

  1. Study of Thermonuclear Alfven Instabilities in Next Step Burning Plasma Experiments

    SciTech Connect

    N.N. Gorelenkov; H.L. Berk; R. Budny; C.Z. Cheng; G.-Y. Fu; W.W. Heidbrink; G. Kramer; D. Meade; and R. Nazikian

    2002-07-02

    A study is presented for the stability of alpha-particle driven shear Alfven Eigenmodes (AE) for the normal parameters of the three major burning plasma proposals, ITER (International Thermonuclear Experimental Reactor), FIRE (Fusion Ignition Research Experiment), and IGNITOR (Ignited Torus). A study of the JET (Joint European Torus) plasma, where fusion alphas were generated in tritium experiments, is also included to attempt experimental validation of the numerical predictions. An analytic assessment of Toroidal AE (TAE) stability is first presented, where the alpha particle beta due to the fusion reaction rate and electron drag is simply and accurately estimated in 7-20 keV plasma temperature regime. In this assessment the hot particle drive is balanced against ion-Landau damping of the background deuterons and electron collision effects and stability boundaries are determined. Then two numerical studies of AE instability are presented. In one the High-n stability code HINST is used . This code is capable of predicting instabilities of low and moderately high frequency Alfven modes. HINST computes the non-perturbative solution of the Alfven eigenmodes including effects of ion finite Larmor radius, orbit width, trapped electrons etc. The stability calculations are repeated using the global code NOVAK. We show that for these tokamaks the spectrum of the least stable AE modes are TAE that appear at medium-/high-n numbers. In HINST TAEs are locally unstable due to the alphas pressure gradient in all the devices under the consideration except IGNITOR. However, NOVAK calculations show that the global mode structure enhances the damping mechanisms and produces stability in all configurations considered here. A serious question remains whether the perturbation theory used in NOVAK overestimates the stability predictions, so that it is premature to conclude that the nominal operation of all three proposals are stable to AEs. In addition NBI ions produce a strong

  2. Laser-fusion targets for reactors

    DOEpatents

    Nuckolls, John H.; Thiessen, Albert R.

    1987-01-01

    A laser target comprising a thermonuclear fuel capsule composed of a centrally located quantity of fuel surrounded by at least one or more layers or shells of material for forming an atmosphere around the capsule by a low energy laser prepulse. The fuel may be formed as a solid core or hollow shell, and, under certain applications, a pusher-layer or shell is located intermediate the fuel and the atmosphere forming material. The fuel is ignited by symmetrical implosion via energy produced by a laser, or other energy sources such as an electron beam machine or ion beam machine, whereby thermonuclear burn of the fuel capsule creates energy for applications such as generation of electricity via a laser fusion reactor.

  3. Post-scram Liquid Metal cooled Fast Breeder Reactor (LMFBR) neat transport system dynamics and steam generator control

    NASA Astrophysics Data System (ADS)

    Brukx, J. F. L. M.

    1982-06-01

    Loop type LMFBR heat transport system dynamics after reactor shutdown and during subsequent decay heat removal are considered with emphasis on steam generator dynamics including the development and evaluation of various post-scram steam generator control systems, and natural circulation of the sodium coolant, including the influence of superimposed free convection on forced convection heat transfer and pressure drop. The normal operating and decay heat removal functions of the overall heat transport system are described.

  4. Multi-scale Control and Enhancement of Reactor Boiling Heat Flux by Reagents and Nanoparticles

    SciTech Connect

    Manglik, R M; Athavale, A; Kalaikadal, D S; Deodhar, A; Verma, U

    2011-09-02

    The phenomenological characterization of the use of non-invasive and passive techniques to enhance the boiling heat transfer in water has been carried out in this extended study. It provides fundamental enhanced heat transfer data for nucleate boiling and discusses the associated physics with the aim of addressing future and next-generation reactor thermal-hydraulic management. It essentially addresses the hypothesis that in phase-change processes during boiling, the primary mechanisms can be related to the liquid-vapor interfacial tension and surface wetting at the solidliquid interface. These interfacial characteristics can be significantly altered and decoupled by introducing small quantities of additives in water, such as surface-active polymers, surfactants, and nanoparticles. The changes are fundamentally caused at a molecular-scale by the relative bulk molecular dynamics and adsorption-desorption of the additive at the liquid-vapor interface, and its physisorption and electrokinetics at the liquid-solid interface. At the micro-scale, the transient transport mechanisms at the solid-liquid-vapor interface during nucleation and bubblegrowth can be attributed to thin-film spreading, surface-micro-cavity activation, and micro-layer evaporation. Furthermore at the macro-scale, the heat transport is in turn governed by the bubble growth and distribution, macro-layer heat transfer, bubble dynamics (bubble coalescence, collapse, break-up, and translation), and liquid rheology. Some of these behaviors and processes are measured and characterized in this study, the outcomes of which advance the concomitant fundamental physics, as well as provide insights for developing control strategies for the molecular-scale manipulation of interfacial tension and surface wetting in boiling by means of polymeric reagents, surfactants, and other soluble surface-active additives.

  5. Probing thermonuclear flame spreading on neutron stars using burst rise oscillations

    NASA Astrophysics Data System (ADS)

    Chakraborty, Manoneeta; Bhattacharyya, Sudip

    2016-07-01

    Intense X-ray bursts (type-I bursts), originated from runaway thermonuclear processes, are observed from the surfaces of many accreting neutron star Low Mass X-ray Binary (LMXB) systems and they provide an important tool to constrain the neutron star equation of state. Periodic intensity variations during these bursts, termed burst oscillations, are observed in about 10% of thermonuclear bursts. Oscillations during the rising phases of thermonuclear bursts are hypothesized to originate from an expanding hot-spot on the surface of the neutron star. We studied the evolution of oscillations during the rising phase of a large sample of thermonuclear bursts from 10 bursting neutron stars in order to probe the process of burning front propagation during an X-ray burst. Our results show observational evidences of expanding hot-spot with spin modulated flame speeds, possibly due to the effects of the Coriolis force present as a result of the high stellar spin (270-620 Hz). This implies that the flame propagation is latitude-dependent and we address the factors affecting the detection and non-detection of burst rise oscillations in the light of this Coriolis force modulated flame spreading scenario.

  6. Evaluation of anticipatory signal to steam generator pressure control program for 700 MWe Indian pressurized heavy water reactor

    SciTech Connect

    Pahari, S.; Hajela, S.; Rammohan, H. P.; Malhotra, P. K.; Ghadge, S. G.

    2012-07-01

    700 MWe Indian Pressurized Heavy Water Reactor (IPHWR) is horizontal channel type reactor with partial boiling at channel outlet. Due to boiling, it has a large volume of vapor present in the primary loops. It has two primary loops connected with the help of pressurizer surge line. The pressurizer has a large capacity and is partly filled by liquid and partly by vapor. Large vapor volume improves compressibility of the system. During turbine trip or load rejection, pressure builds up in Steam Generator (SG). This leads to pressurization of Primary Heat Transport System (PHTS). To control pressurization of SG and PHTS, around 70% of the steam generated in SG is dumped into the condenser by opening Condenser Steam Dump Valves (CSDVs) and rest of the steam is released to the atmosphere by opening Atmospheric Steam Discharge Valves (ASDVs) immediately after sensing the event. This is accomplished by adding anticipatory signal to the output of SG pressure controller. Anticipatory signal is proportional to the thermal power of reactor and the proportionality constant is set so that SG pressure controller's output jacks up to ASDV opening range when operating at 100% FP. To simulate this behavior for 700 MWe IPHWR, Primary and secondary heat transport system is modeled. SG pressure control and other process control program have also been modeled to capture overall plant dynamics. Analysis has been carried out with 3-D neutron kinetics coupled thermal hydraulic computer code ATMIKA.T to evaluate the effect of the anticipatory signal on PHT pressure and over all plant dynamics during turbine trip in 700 MWe IPHWR. This paper brings out the results of the analysis with and without considering anticipatory signal in SG pressure control program during turbine trip. (authors)

  7. Optimization of the activated sludge anoxic reactor configuration as a means to control nutrient removal kinetically.

    PubMed

    Plósz, Benedek Gy

    2007-04-01

    Factors influencing the determination of optimum reactor configuration for activated sludge denitrification are investigated in this paper. A kinetic optimization method is presented to evaluate optimal pre- and post-denitrification bioreactor stages. Applying the method developed, simulation studies were carried out to investigate the impacts of the ratio of the influent readily biodegradable and slowly biodegradable substrates and the oxygen entering the denitrification zones on the optimal anoxic reactor configuration. In addition, the paper describes the effects of the slowly biodegradable substrate on the denitrification efficiency using external substrate dosing, and it demonstrates kinetic considerations concerning the hydrolysis process. It has been shown that as a function of the biodegradable substrate composition, the stage system design with three optimized reactor compartments can effectively increase reaction rates in the denitrification zones, and can provide flexibility for varying operation conditions. PMID:17321565

  8. Fusion reactor materials: Semiannual progress report for the period ending March 31, 1988

    SciTech Connect

    none,

    1988-08-01

    This report contains papers on thermonuclear reactor materials. The general categories of these papers are: irradiation facilities, test matrices, and experimental methods; dosimetry, damage parameters and activation calculations; materials engineering and design requirements; fundamental mechanical behavior; development of structural alloys; solid breeding materials; ceramics; and radiation effects. Selected papers have been processed for inclusion in the energy database. (LSP)

  9. Fusion Reactor Materials semiannual progress report for period ending September 30, 1991

    SciTech Connect

    none,

    1992-04-01

    This report contains papers on topic in the following areas of thermonuclear reactor materials: irradiation facilities, test matrices, and experimental methods; dosimetry, damage parameters and activation calculations; materials engineering and design requirements; fundamental mechanical behavior; radiation effects; development of structural alloys; solid breeding materials and beryllium; and ceramics. These paper have been index separately elsewhere. (LSP).

  10. Fusion reactor materials semiannual progress report for the period ending March 31, 1990

    SciTech Connect

    Not Available

    1990-08-01

    This report mainly discusses topics on the physical effects of radiation on thermonuclear reactor materials. The areas discussed are: irradiation facilities, test matrices, and experimental methods; dosimetry, damage parameters, and activation calculations; fundamental mechanical behavior; radiation effects; mechanistic studies, theory and modeling; development of structural alloys; solid breeding materials; and ceramics. (FI)

  11. Adsorptive control of water in esterification with immobilized enzymes: II. fixed-bed reactor behavior.

    PubMed

    Mensah, P; Gainer, J L; Carta, G

    1998-11-20

    Experimental and theoretical studies are conducted to understand the dynamic behavior of a continuous-flow fixed-bed reactor in which an esterification is catalyzed by an immobilized enzyme in an organic solvent medium. The experimental system consists of a commercial immobilized lipase preparation known as Lipozyme as the biocatalyst, with propionic acid and isoamyl alcohol (dissolved in hexane) as the reaction substrates. A complex dynamic behavior is observed experimentally as a result of the simultaneous occurrence of reaction and adsorption phenomena. Both propionic acid and water are adsorbed by the biocatalyst resulting in lower reaction rates. In addition, an excessive accumulation of water in the reactor leads to a rapid irreversible inactivation of the enzyme. A model based on previously-obtained adsorption isotherms and kinetic expressions, as well as on adsorption rate measurements obtained in this work, is used to predict the concentration and thermodynamic activity of water along the reactor length. The model successfully predicts the dynamic behavior of the reactor and shows that a maximum thermodynamic activity of water occurs at a point at some distance from the reactor entrance. A cation exchange resin in sodium form, packed in the reactor as a selective water adsorbent together with the catalyst particles, is shown to be an effective means for preventing an excessive accumulation of water formed in the reaction. Its use results in longer cycle times and greater productivity. As predicted by the model, the experimental results show that the water adsorbed on the catalyst and on the ion exchange resin can be removed with isoamyl alcohol with no apparent loss in enzyme activity.

  12. Microscale packed bed reactor for controlled hydrogen peroxide decomposition as a fuel cell oxidant aboard unmanned undersea vehicles

    NASA Astrophysics Data System (ADS)

    Lennon, E.; Burke, A. A.; Ocampo, M.; Besser, R. S.

    The multiphase catalytic decomposition of hydrogen peroxide into water and oxygen is notoriously susceptible to thermal runaway (heat of reaction: -98 kJ mol -1). The high surface area to volume ratio (S/ V) in a microscale packed bed (MPB) reactor (radius 0.5 mm) was investigated for reducing the risk of thermal runaway during hydrogen peroxide decomposition to oxygen intended as a fuel cell oxidant aboard an unmanned undersea vehicle (UUV). A microscale reactor channel with a S/ V of ∼2 × 10 3 m 2 m -3 simulated under convective cooling generated a significant heat rise (T rise ∼ 100 K), whereas a microreactor with a higher S/ V (∼200 × 10 3 m 2 m -3) achieved thermal control (T rise < 10 K) over the simulated reaction zone. Although thermal management was successfully accomplished using the higher S/ V, experimental conversions of hydrogen peroxide to oxygen (5-18%) measured from the outlet were lower than simulated conversions (38-63%). Simulation assumptions, such as homogeneously dispersed flow and perfect catalyst interaction among other factors, contributed to the discrepancies between the simulated and experimental degrees of peroxide conversion to oxygen. Even though thermal control of the MPB was achieved, this work indicates that mass transfer limitations are a factor in the MPB reactor during a multiphase reaction, like decomposition of hydrogen peroxide to oxygen and water, and suggests means to overcome them even on the microscale level.

  13. Partitionable-space enhanced coagulation (PEC) reactor and its working mechanism: a new prospective chemical technology for phosphorus pollution control.

    PubMed

    Zhang, Meng; Zheng, Ping; Abbas, Ghulam; Chen, Xiaoguang

    2014-02-01

    Phosphorus pollution control and phosphorus recycling, simultaneously, are focus of attention in the wastewater treatment. In this work, a novel reactor named partitionable-space enhanced coagulation (PEC) was invented for phosphorus control. The working performance and process mechanism of PEC reactor were investigated. The results showed that the PEC technology was highly efficient and cost-effective. The volumetric removal rate (VRR) reached up to 2.86 ± 0.04 kg P/(m(3) d) with a phosphorus removal rate of over 97%. The precipitant consumption was reduced to 2.60-2.76 kg Fe(II)/kg P with low operational cost of $ 0.632-0.673/kg P. The peak phosphorus content in precipitate was up to 30.44% by P2O5, which reveal the benefit of the recycling phosphorus resource. The excellent performance of PEC technology was mainly attributed to the partitionable-space and 'flocculation filter'. The partition limited the trans-regional back-mixing of reagents along the reactor, which promoted the precipitation reaction. The 'flocculation filter' retained the microflocs, enhancing the flocculation process.

  14. Synthesis of nanoparticles in a flame aerosol reactor with independent and strict control of their size, crystal phase and morphology

    NASA Astrophysics Data System (ADS)

    Jiang, Jingkun; Chen, Da-Ren; Biswas, Pratim

    2007-07-01

    A flame aerosol reactor (FLAR) was developed to synthesize nanoparticles with desired properties (crystal phase and size) that could be independently controlled. The methodology was demonstrated for TiO2 nanoparticles, and this is the first time that large sets of samples with the same size but different crystal phases (six different ratios of anatase to rutile in this work) were synthesized. The degree of TiO2 nanoparticle agglomeration was determined by comparing the primary particle size distribution measured by scanning electron microscopy (SEM) to the mobility-based particle size distribution measured by online scanning mobility particle spectrometry (SMPS). By controlling the flame aerosol reactor conditions, both spherical unagglomerated particles and highly agglomerated particles were produced. To produce monodisperse nanoparticles, a high throughput multi-stage differential mobility analyser (MDMA) was used in series with the flame aerosol reactor. Nearly monodisperse nanoparticles (geometric standard deviation less than 1.05) could be collected in sufficient mass quantities (of the order of 10 mg) in reasonable time (1 h) that could be used in other studies such as determination of functionality or biological effects as a function of size.

  15. A Comparison of Photocatalytic Oxidation Reactor Performance for Spacecraft Cabin Trace Contaminant Control Applications

    NASA Technical Reports Server (NTRS)

    Perry, Jay L.; Frederick, Kenneth R.; Scott, Joseph P.; Reinermann, Dana N.

    2011-01-01

    Photocatalytic oxidation (PCO) is a maturing process technology that shows potential for spacecraft life support system application. Incorporating PCO into a spacecraft cabin atmosphere revitalization system requires an understanding of basic performance, particularly with regard to partial oxidation product production. Four PCO reactor design concepts have been evaluated for their effectiveness for mineralizing key trace volatile organic com-pounds (VOC) typically observed in crewed spacecraft cabin atmospheres. Mineralization efficiency and selectivity for partial oxidation products are compared for the reactor design concepts. The role of PCO in a spacecraft s life support system architecture is discussed.

  16. Stabilized three-stage oxidation of DME/air mixture in a micro flow reactor with a controlled temperature profile

    SciTech Connect

    Oshibe, Hiroshi; Nakamura, Hisashi; Tezuka, Takuya; Hasegawa, Susumu; Maruta, Kaoru

    2010-08-15

    Ignition and combustion characteristics of a stoichiometric dimethyl ether (DME)/air mixture in a micro flow reactor with a controlled temperature profile which was smoothly ramped from room temperature to ignition temperature were investigated. Special attention was paid to the multi-stage oxidation in low temperature condition. Normal stable flames in a mixture flow in the high velocity region, and non-stationary pulsating flames and/or repetitive extinction and ignition (FREI) in the medium velocity region were experimentally confirmed as expected from our previous study on a methane/air mixture. In addition, stable double weak flames were observed in the low velocity region for the present DME/air mixture case. It is the first observation of stable double flames by the present methodology. Gas sampling was conducted to obtain major species distributions in the flow reactor. The results indicated that existence of low-temperature oxidation was conjectured by the production of CH{sub 2}O occured in the upstream side of the experimental first luminous flame, while no chemiluminescence from it was seen. One-dimensional computation with detailed chemistry and transport was conducted. At low mixture velocities, three-stage oxidation was confirmed from profiles of the heat release rate and major chemical species, which was broadly in agreement with the experimental results. Since the present micro flow reactor with a controlled temperature profile successfully presented the multi-stage oxidations as spatially separated flames, it is shown that this flow reactor can be utilized as a methodology to separate sets of reactions, even for other practical fuels, at different temperature. (author)

  17. Analysis of supercritical CO{sub 2} cycle control strategies and dynamic response for Generation IV Reactors.

    SciTech Connect

    Moisseytsev, A.; Sienicki, J. J.

    2011-04-12

    The analysis of specific control strategies and dynamic behavior of the supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle has been extended to the two reactor types selected for continued development under the Generation IV Nuclear Energy Systems Initiative; namely, the Very High Temperature Reactor (VHTR) and the Sodium-Cooled Fast Reactor (SFR). Direct application of the standard S-CO{sub 2} recompression cycle to the VHTR was found to be challenging because of the mismatch in the temperature drop of the He gaseous reactor coolant through the He-to-CO{sub 2} reactor heat exchanger (RHX) versus the temperature rise of the CO{sub 2} through the RHX. The reference VHTR features a large temperature drop of 450 C between the assumed core outlet and inlet temperatures of 850 and 400 C, respectively. This large temperature difference is an essential feature of the VHTR enabling a lower He flow rate reducing the required core velocities and pressure drop. In contrast, the standard recompression S-CO{sub 2} cycle wants to operate with a temperature rise through the RHX of about 150 C reflecting the temperature drop as the CO{sub 2} expands from 20 MPa to 7.4 MPa in the turbine and the fact that the cycle is highly recuperated such that the CO{sub 2} entering the RHX is effectively preheated. Because of this mismatch, direct application of the standard recompression cycle results in a relatively poor cycle efficiency of 44.9%. However, two approaches have been identified by which the S-CO{sub 2} cycle can be successfully adapted to the VHTR and the benefits of the S-CO{sub 2} cycle, especially a significant gain in cycle efficiency, can be realized. The first approach involves the use of three separate cascaded S-CO{sub 2} cycles. Each S-CO{sub 2} cycle is coupled to the VHTR through its own He-to-CO{sub 2} RHX in which the He temperature is reduced by 150 C. The three respective cycles have efficiencies of 54, 50, and 44%, respectively, resulting in a net cycle

  18. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1962-12-25

    A reactor is described comprising a plurality of horizontal trays containing a solution of a fissionable material, the trays being sleeved on a vertical tube which contains a vertically-reciprocable control rod, a gas-tight chamber enclosing the trays, and means for conducting vaporized moderator from the chamber and for replacing vaporized moderator in the trays. (AEC)

  19. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.; Weinberg, A.W.; Young, G.J.

    1958-04-15

    A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.

  20. Reactor System Transient Code.

    1999-07-14

    RELAP3B describes the behavior of water-cooled nuclear reactors during postulated accidents or power transients, such as large reactivity excursions, coolant losses or pump failures. The program calculates flows, mass and energy inventories, pressures, temperatures, and steam qualities along with variables associated with reactor power, reactor heat transfer, or control systems. Its versatility allows one to describe simple hydraulic systems as well as complex reactor systems.

  1. Technical Basis for Physical Fidelity of NRC Control Room Training Simulators for Advanced Reactors

    SciTech Connect

    Minsk, Brian S.; Branch, Kristi M.; Bates, Edward K.; Mitchell, Mark R.; Gore, Bryan F.; Faris, Drury K.

    2009-10-09

    The objective of this study is to determine how simulator physical fidelity influences the effectiveness of training the regulatory personnel responsible for examination and oversight of operating personnel and inspection of technical systems at nuclear power reactors. It seeks to contribute to the U.S. Nuclear Regulatory Commission’s (NRC’s) understanding of the physical fidelity requirements of training simulators. The goal of the study is to provide an analytic framework, data, and analyses that inform NRC decisions about the physical fidelity requirements of the simulators it will need to train its staff for assignment at advanced reactors. These staff are expected to come from increasingly diverse educational and experiential backgrounds.

  2. NUCLEAR REACTOR

    DOEpatents

    Christy, R.F.

    1958-07-15

    A nuclear reactor of the homogeneous liquid fuel type is described wherein the fissionable isotope is suspended or dissolved in a liquid moderator such as water. The reactor core is comprised essentially of a spherical vessel for containing the reactive composition surrounded by a reflector, preferably of beryllium oxide. The reactive composition may be an ordinary water solution of a soluble salt of uranium, the quantity of fissionable isotope in solution being sufficient to provide a critical mass in the vessel. The liquid fuel is stored in a tank of non-crtttcal geometry below the reactor vessel and outside of the reflector and is passed from the tank to the vessel through a pipe connecting the two by air pressure means. Neutron absorbing control and safety rods are operated within slots in the reflector adjacent to the vessel.

  3. An analysis of thermionic space nuclear reactor power system: II. Merits of using safety drums for backup control

    NASA Astrophysics Data System (ADS)

    El-Genk, Mahomed S.; Xue, Huimin

    1993-01-01

    An analysis is performed to investigate the merits of using the TOPAZ-II safety drums for a backup control to prevent a reactivity excursion, stabilize the reactor, and achieve steady-state power operation, following a severe hypothetical reactivity initiated accident (RIA). Such an RIA is assumed to occur during the system start-up in orbit due to a malfunction of the drive mechanism of the control drums, causing the nine drums to accidentally rotate the full 180° outward. Results show that an immediate, inward rotation of the three safety drums to an angle of 80° will shutdown the reactor, however, a delay time of 10 s will not only prevents a reactivity excursion, but also enables operating the reactor at a steady-state thermal power of about 33.3 kW (0.9 kW per TFE). Conversely, when the immediate rotation of the safety drums is to a larger angle of 100°, a steady-state operation at about 37 kW can be achieved, but a delay of 10 s causes a reactivity excursion and overheating of the TFEs. It is therefor concluded that, should the drive mechanism be modified to enable rotating the safety drums for TOPAZ-II reactor at variable speeds of and below 22.5°/s, the three safety drums could be used successfully for a backup control, following an RIA. However, since the reactivity worth of the three safety drums is only 2.0, the maximum steady-state electric power achievable for the system is limited to approximately 0.25 kW, at which the fission power is about 37 kW and the emitter temperature is approximaely 1500 K. To alleviate such a limitation and enable operation at nominal design conditions (fission power of about 107 kW or a system's total electric power of 5.6 kW), the reactivity worth of the safety drums would have to be increased by at least 0.24. An additional increase in the safety drums' worth will also be necessary to maintain steady-state operation of the system at nominal conditions throughout the mission lifetime, with all nine control drums fully

  4. The preliminary design of bearings for the control system of a high-temperature lithium-cooled nuclear reactor

    NASA Technical Reports Server (NTRS)

    Yacobucci, H. G.; Waldron, W. D.; Walowit, J. A.

    1973-01-01

    The design of bearings for the control system of a fast reactor concept is presented. The bearings are required to operate at temperatures up to 2200 F in one of two fluids, lithium or argon. Basic bearing types are the same regardless of the fluid. Crowned cylindrical journals were selected for radially loaded bearings and modified spherical bearings were selected for bearings under combined thrust and radial loads. Graphite and aluminum oxide are the materials selected for the argon atmosphere bearings while cermet compositions (carbides or nitrides bonded with refractory metals) were selected for the lithium lubricated bearings. Mounting of components is by shrink fit or by axial clamping utilizing differential thermal expansion.

  5. Application of a fluidized bed reactor charged with aragonite for control of alkalinity, pH and carbon dioxide in marine recirculating aquaculture systems

    USGS Publications Warehouse

    Paul S Wills, PhD; Pfeiffer, Timothy; Baptiste, Richard; Watten, Barnaby J.

    2016-01-01

    Control of alkalinity, dissolved carbon dioxide (dCO2), and pH are critical in marine recirculating aquaculture systems (RAS) in order to maintain health and maximize growth. A small-scale prototype aragonite sand filled fluidized bed reactor was tested under varying conditions of alkalinity and dCO2 to develop and model the response of dCO2 across the reactor. A large-scale reactor was then incorporated into an operating marine recirculating aquaculture system to observe the reactor as the system moved toward equilibrium. The relationship between alkalinity dCO2, and pH across the reactor are described by multiple regression equations. The change in dCO2 across the small-scale reactor indicated a strong likelihood that an equilibrium alkalinity would be maintained by using a fluidized bed aragonite reactor. The large-scale reactor verified this observation and established equilibrium at an alkalinity of approximately 135 mg/L as CaCO3, dCO2 of 9 mg/L, and a pH of 7.0 within 4 days that was stable during a 14 day test period. The fluidized bed aragonite reactor has the potential to simplify alkalinity and pH control, and aid in dCO2 control in RAS design and operation. Aragonite sand, purchased in bulk, is less expensive than sodium bicarbonate and could reduce overall operating production costs.

  6. Population dynamics in controlled unsteady-state systems: An application to the degradation of glyphosate in a sequencing batch reactor

    SciTech Connect

    Devarakonda, M.S.

    1988-01-01

    Control over population dynamics and organism selection in a biological waste treatment system provides an effective means of engineering process efficiency. Examples of applications of organism selection include control of filamentous organisms, biological nutrient removal, industrial waste treatment requiring the removal of specific substrates, and hazardous waste treatment. Inherently, full scale biological waste treatment systems are unsteady state systems due to the variations in the waste streams and mass flow rates of the substrates. Some systems, however, have the capacity to impose controlled selective pressures on the biological population by means of their operation. An example of such a system is the Sequencing Batch Reactor (SBR) which was the experimental system utilized in this research work. The concepts of organism selection were studied in detail for the biodegradation of a herbicide waste stream, with glyphosate as the target compound. The SBR provided a reactor configuration capable of exerting the necessary selective pressures to select and enrich for a glyphosate degrading population. Based on results for bench scale SBRs, a hypothesis was developed to explain population dynamics in glyphosate degrading systems.

  7. An attempt to minimize the temperature gradient along a plug-flow methane/steam reforming reactor by adopting locally controlled heating zones

    NASA Astrophysics Data System (ADS)

    Mozdzierz, M.; Brus, G.; Sciazko, A.; Komatsu, Y.; Kimijima, S.; Szmyd, J. S.

    2014-08-01

    Plug flow reactors are very common in the chemical process industry, including methane/steam reforming applications. Their operation presents many challenges, such as a strong dependence of temperature and composition distribution on the inlet conditions. The strongly endothermic methane/steam reforming reaction might result in a temperature drop at the inlet of the reactor and consequently the occurrence of large temperature gradients. The strongly non-uniform temperature distribution due to endothermic chemical reaction can have tremendous consequences on the operation of the reactor, such as catalyst degradation, undesired side reactions and thermal stresses. To avoid such unfavorable conditions, thermal management of the reactor becomes an important issue. To carry out thermal management properly, detailed modeling and corresponding numerical analyses of the phenomena occurring inside the reforming system is required. This paper presents experimental and numerical studies on the methane/steam reforming process inside a plug-flow reactor. To optimize the reforming reactors, detailed data about the entire reforming process is required. In this study the kinetics of methane/steam reforming on the Ni/YSZ catalyst was experimentally investigated. Measurements including different thermal boundary conditions, the fuel flow rate and the steam- to-methane ratios were performed. The reforming rate equation derived from experimental data was used in the numerical model to predict gas composition and temperature distribution along the steam-reforming reactor. Finally, an attempt was made to control the temperature distribution by adopting locally controlled heating zones.

  8. An analysis of thermionic space nuclear reactor power system: II. Merits of using safety drums for backup control

    SciTech Connect

    El-Genk, M.S.; Huimin Xue )

    1993-01-10

    An analysis is performed to investigate the merits of using the TOPAZ-II safety drums for a backup control to prevent a reactivity excursion, stabilize the reactor, and achieve steady-state power operation, following a severe hypothetical reactivity initiated accident (RIA). Such an RIA is assumed to occur during the system start-up in orbit due to a malfunction of the drive mechanism of the control drums, causing the nine drums to accidentally rotate the full 180[degree] outward. Results show that an immediate, inward rotation of the three safety drums to an angle of 80[degree] will shutdown the reactor, however, a delay time of 10 s will not only prevents a reactivity excursion, but also enables operating the reactor at a steady-state thermal power of about 33.3 kW (0.9 kW per TFE). Conversely, when the immediate rotation of the safety drums is to a larger angle of 100[degree], a steady-state operation at about 37 kW can be achieved, but a delay of 10 s causes a reactivity excursion and overheating of the TFEs. It is therefor concluded that, should the drive mechanism be modified to enable rotating the safety drums for TOPAZ-II reactor at variable speeds of and below 22.5[degree]/s, the three safety drums could be used successfully for a backup control, following an RIA. However, since the reactivity worth of the three safety drums is only $2.0, the maximum steady-state electric power achievable for the system is limited to approximately 0.25 kW, at which the fission power is about 37 kW and the emitter temperature is approximaely 1500 K. To alleviate such a limitation and enable operation at nominal design conditions (fission power of about 107 kW or a system's total electric power of 5.6 kW), the reactivity worth of the safety drums would have to be increased by at least $0.24.

  9. A Deep Search for Prompt Radio Emission from Thermonuclear Supernovae with the Very Large Array

    NASA Astrophysics Data System (ADS)

    Chomiuk, Laura; Soderberg, Alicia M.; Chevalier, Roger A.; Bruzewski, Seth; Foley, Ryan J.; Parrent, Jerod; Strader, Jay; Badenes, Carles; Fransson, Claes; Kamble, Atish; Margutti, Raffaella; Rupen, Michael P.; Simon, Joshua D.

    2016-04-01

    Searches for circumstellar material around Type Ia supernovae (SNe Ia) are some of the most powerful tests of the nature of SN Ia progenitors, and radio observations provide a particularly sensitive probe of this material. Here, we report radio observations for SNe Ia and their lower-luminosity thermonuclear cousins. We present the largest, most sensitive, and spectroscopically diverse study of prompt ({{Δ }}t≲ 1 years) radio observations of 85 thermonuclear SNe, including 25 obtained by our team with the unprecedented depth of the Karl G. Jansky Very Large Array. With these observations, SN 2012cg joins SN 2011fe and SN 2014J as an SN Ia with remarkably deep radio limits and excellent temporal coverage (six epochs, spanning 5-216 days after explosion, implying \\dot{M}/{v}w≲ 5× 10-9 M⊙) yr-1/(100 km s-1), assuming ɛB = 0.1 and ɛe = 0.1). All observations yield non-detections, placing strong constraints on the presence of circumstellar material. We present analytical models for the temporal and spectral evolution of prompt radio emission from thermonuclear SNe as expected from interaction with either wind-stratified or uniform density media. These models allow us to constrain the progenitor mass loss rates, with limits in the range of \\dot{M}≲ 10-9-10-4 M⊙ yr-1, assuming a wind velocity of vw = 100 km s-1. We compare our radio constraints with measurements of Galactic symbiotic binaries to conclude that ≲10% of thermonuclear SNe have red giant companions.

  10. Frontiers in propulsion research: Laser, matter-antimatter, excited helium, energy exchange thermonuclear fusion

    NASA Technical Reports Server (NTRS)

    Papailiou, D. D. (Editor)

    1975-01-01

    Concepts are described that presently appear to have the potential for propulsion applications in the post-1990 era of space technology. The studies are still in progress, and only the current status of investigation is presented. The topics for possible propulsion application are lasers, nuclear fusion, matter-antimatter annihilation, electronically excited helium, energy exchange through the interaction of various fields, laser propagation, and thermonuclear fusion technology.

  11. 1D-Simulation of Thermonuclear Target Compression and Burning for Laser Facility NIF and LMJ

    NASA Astrophysics Data System (ADS)

    Valiev, R. Zh.; Chizhkov, M. N.; Karlyhanov, N. G.; Lusganova, O. V.; Lykov, V. A.; Netsvetayev, D. S.; Timakova, M. S.

    2006-08-01

    The high-power laser facilities NIF and LMJ with the pulse energy as high as 2 MJ are being created in the USA and France. The basic cryogenic indirect-drive targets for thermonuclear ignition on these facilities are a spherical shell from polystyrene doped with oxygen and bromine. (CH+5%O+0,25%Br), whose inner surface is covered with DT-ice layer. The central region of targets is filled with DT-gas. The targets for NIF and LMJ have different external radii (1,11 and 1,215 mm, correspondingly), masses of DT-fuel (210 и 310 μg), X-ray radiation temperature dependences in time. The thermonuclear yield from the NIF target calculated with LASNEX code is 15 MJ, the yield from the LMJ target calculated with FCI1 code is 25.4 MJ. In RFNC-VNIITF calculations of compression and burning of basic NIF and LMJ targets were performed by using of the 1D ERA code in the spectral diffusion approximation for radiation transfer. We used tabulated opacity calculated by the mean ion model. Thermonuclear yield calculated with ERA code is about 18 MJ for the NIF target and nearly 23 MJ for the LMJ target. Calculated yields are in good agreement with published results. Performed calculations justified the possibility to simulate ICF targets in RFNC-VNIITF. In paper are also presented analysis results of target sensitivity to opacity and X-ray temperature variations.

  12. Rocket propulsion by thermonuclear micro-bombs ignited with intense relativistic electron beams.

    NASA Technical Reports Server (NTRS)

    Winterberg, F.

    1971-01-01

    Discussion of a method for the ignition of a thermonuclear microbomb by means of an intense relativistic electron beam with regard to its potential application to rocket propulsion. With such a system, exhaust velocities up to 1000 km/sec, corresponding to a specific impulse of 100,000 sec, seem to be within the realm of possibility. The rocket is propelled by a chain of thermonuclear microbombs exploded in a concave magnetic mirror produced by superconducting field coils. The magnetic pressure of the field reflects the fireball generated by the explosion. For the large capacitor bank required to generate the intense relativistic electron beam, a desirable lightweight design may be possible through use of ferroelectric materials. Because of the high cost of the T-D and He 3-D thermonuclear material, the system has to be optimized by minimizing the T-D and He 3-D consumption by a proper TD and He 3-D fuel to hydrogen propellant mass ratio, leading to a larger total system mass than would be absolutely necessary.

  13. Experimental investigation of the 30S(α, p) thermonuclear reaction in x-ray bursts

    NASA Astrophysics Data System (ADS)

    Kahl, D.; Chen, A. A.; Kubono, S.; Yamaguchi, H.; Binh, D. N.; Chen, J.; Cherubini, S.; Duy, N. N.; Hashimoto, T.; Hayakawa, S.; Iwasa, N.; Jung, H. S.; Kato, S.; Kwon, Y. K.; Nishimura, S.; Ota, S.; Setoodehnia, K.; Teranishi, T.; Tokieda, H.; Yamada, T.; Yun, C. C.; Zhang, L. Y.

    2016-02-01

    We performed the first measurement of 30S+α resonant elastic scattering to experimentally examine the 30S(α, p) stellar reaction rate in type I x-ray bursts. These bursts are the most frequent thermonuclear explosions in the galaxy, resulting from thermonuclear runaway on the surface of accreting neutron star binaries. The 30S(α, p) reaction plays a critical role in burst models, yet very little is known about the compound nucleus 34Ar at these energies nor the reaction rate itself. We performed a measurement of alpha elastic scattering with a radioactive beam of 30S to experimentally probe the entrance channel. Utilizing a gaseous active target system and silicon detector array, we extracted the excitation function from 1.8 to 5.5 MeV near 160° in the center-of-mass frame. The experimental data were analyzed with an R-Matrix calculation, and we discovered several new resonances and extracted their quantum properties (resonance energy, width, spin, and parity). Finally, we calculated the narrow resonant thermonuclear reaction rate of 30S(α, p) for these new resonances.

  14. Effect of inlet temperature on the performance of a catalytic reactor. [air pollution control

    NASA Technical Reports Server (NTRS)

    Anderson, D. N.

    1978-01-01

    A 12 cm diameter by 15 cm long catalytic reactor was tested with No. 2 diesel fuel in a combustion test rig at inlet temperatures of 700, 800, 900, and 1000 K. Other test conditions included pressures of 3 and 6 x 10 to the 5th power Pa, reference velocities of 10, 15, and 20 m/s, and adiabatic combustion temperatures in the range 1100 to 1400 K. The combustion efficiency was calculated from measurements of carbon monoxide and unburned hydrocarbon emissions. Nitrogen oxide emissions and reactor pressure drop were also measured. At a reference velocity of 10 m/s, the CO and unburned hydrocarbons emissions, and, therefore, the combustion efficiency, were independent of inlet temperature. At an inlet temperature of 1000 K, they were independent of reference velocity. Nitrogen oxides emissions resulted from conversion of the small amount (135 ppm) of fuel-bound nitrogen in the fuel. Up to 90 percent conversion was observed with no apparent effect of any of the test variables. For typical gas turbine operating conditions, all three pollutants were below levels which would permit the most stringent proposed automotive emissions standards to be met.

  15. Characteristics and control response of the TOPAZ II Reactor System Real-time Dynamic Simulator

    SciTech Connect

    Kwok, K.S.

    1993-11-12

    A dynamic simulator of the TOPAZ II reactor system has been developed for the Nuclear Electric Propulsion Space Test Program. The simulator combines first-principle modeling and empirical correlations in its algorithm to attain the modeling accuracy and computational through-put that are required for real-time execution. The overall execution time of the simulator for each time step is 15 ms when no data is written to the disk, and 18 ms when nine double precision data points are written to the disk once in every time step. The simulation program has been tested and it is able to handle a step decrease of $8 worth of reactivity. It also provides simulations of fuel, emitter, collector, stainless steel, and ZrH moderator failures. Presented in this paper are the models used in the calculations, a sample simulation session, and a discussion of the performance and limitations of the simulator. The simulator has been found to provide realistic real-time dynamic response of the TOPAZ II reactor system under both normal and casualty conditions.

  16. Maintaining a Critical Spectra within Monteburns for a Gas-Cooled Reactor Array by Way of Control Rod Manipulation

    DOE PAGESBeta

    Adigun, Babatunde John; Fensin, Michael Lorne; Galloway, Jack D.; Trellue, Holly Renee

    2016-06-07

    Our burnup study examined the effect of a predicted critical control rod position on the nuclide predictability of several axial and radial locations within a 4×4 graphite moderated gas cooled reactor fuel cluster geometry. To achieve this, a control rod position estimator (CRPE) tool was developed within the framework of the linkage code Monteburns between the transport code MCNP and depletion code CINDER90, and four methodologies were proposed within the tool for maintaining criticality. Two of the proposed methods used an inverse multiplication approach - where the amount of fissile material in a set configuration is slowly altered until criticalitymore » is attained - in estimating the critical control rod position. Another method carried out several MCNP criticality calculations at different control rod positions, then used a linear fit to estimate the critical rod position. The final method used a second-order polynomial fit of several MCNP criticality calculations at different control rod positions to guess the critical rod position. The results showed that consistency in prediction of power densities as well as uranium and plutonium isotopics was mutual among methods within the CRPE tool that predicted critical position consistently well. Finall, while the CRPE tool is currently limited to manipulating a single control rod, future work could be geared toward implementing additional criticality search methodologies along with additional features.« less

  17. NUCLEAR REACTOR

    DOEpatents

    Treshow, M.

    1958-08-19

    A neuclear reactor is described of the heterogeneous type and employing replaceable tubular fuel elements and heavy water as a coolant and moderator. A pluraltty of fuel tubesa having their axes parallel, extend through a tank type pressure vessel which contatns the liquid moderator. The fuel elements are disposed within the fuel tubes in the reaetive portion of the pressure vessel during normal operation and the fuel tubes have removable plug members at each end to permit charging and discharging of the fuel elements. The fuel elements are cylindrical strands of jacketed fissionable material having helical exterior ribs. A bundle of fuel elements are held within each fuel tube with their longitudinal axes parallel, the ribs serving to space them apart along their lengths. Coolant liquid is circulated through the fuel tubes between the spaced fuel elements. Suitable control rod and monitoring means are provided for controlling the reactor.

  18. The application of an innovative continuous multiple tube reactor as a strategy to control the specific organic loading rate for biohydrogen production by dark fermentation.

    PubMed

    Gomes, Simone D; Fuess, Lucas T; Penteado, Eduardo D; Lucas, Shaiane D M; Gotardo, Jackeline T; Zaiat, Marcelo

    2015-12-01

    Biohydrogen production in fixed-bed reactors often leads to unstable and decreasing patterns because the excessive accumulation of biomass in the bed negatively affects the specific organic loading rate (SOLR) applied to the reactor. In this context, an innovative reactor configuration, i.e., the continuous multiple tube reactor (CMTR), was assessed in an attempt to better control the SOLR for biohydrogen production. The CMTR provides a continuous discharge of biomass, preventing the accumulation of solids in the long-term. Sucrose was used as the carbon source and mesophilic temperature conditions (25°C) were applied in three continuous assays. The reactor showed better performance when support material was placed in the outlet chamber to enhance biomass retention within the reactor. Although the SOLR could not be effectively controlled, reaching values usually higher than 10gsucroseg(-1)VSSd(-1), the volumetric hydrogen production and molar hydrogen production rates peaked, respectively, at 1470mLH2L(-1)d(-1) and 45mmolH2d(-1), indicating that the CMTR was a suitable configuration for biohydrogen production.

  19. Development of fusion blanket technology for the DEMO reactor.

    PubMed

    Colling, B R; Monk, S D

    2012-07-01

    The viability of various materials and blanket designs for use in nuclear fusion reactors can be tested using computer simulations and as parts of the test blanket modules within the International Thermonuclear Experimental Reactor (ITER) facility. The work presented here focuses on blanket model simulations using the Monte Carlo simulation package MCNPX (Computational Physics Division Los Alamos National Laboratory, 2010) and FISPACT (Forrest, 2007) to evaluate the tritium breeding capability of a number of solid and liquid breeding materials. The liquid/molten salt breeders are found to have the higher tritium breeding ratio (TBR) and are to be considered for further analysis of the self sufficiency timing.

  20. Development of fusion blanket technology for the DEMO reactor.

    PubMed

    Colling, B R; Monk, S D

    2012-07-01

    The viability of various materials and blanket designs for use in nuclear fusion reactors can be tested using computer simulations and as parts of the test blanket modules within the International Thermonuclear Experimental Reactor (ITER) facility. The work presented here focuses on blanket model simulations using the Monte Carlo simulation package MCNPX (Computational Physics Division Los Alamos National Laboratory, 2010) and FISPACT (Forrest, 2007) to evaluate the tritium breeding capability of a number of solid and liquid breeding materials. The liquid/molten salt breeders are found to have the higher tritium breeding ratio (TBR) and are to be considered for further analysis of the self sufficiency timing. PMID:22112596

  1. Performance Characterization of a Prototype Ultra-Short Channel Monolith Catalytic Reactor for Air Quality Control Applications

    NASA Technical Reports Server (NTRS)

    Perry, J. L.; Tomes, K. M.; Roychoudhury, S.; Tatara, J. D.

    2005-01-01

    Contaminated air and process gases, whether in a crewed spacecraft cabin atmosphere, the working volume of a microgravity science or ground-based laboratory experiment facility, or the exhaust from an automobile, are pervasive problems that ultimately effect human health, performance, and well-being. The need for highly-effective, economical decontamination processes spans a wide range of terrestrial and space flight applications. Adsorption processes are used widely for process gas decontamination. Most industrial packed bed adsorption processes use activated carbon because it is cheap and highly effective. Once saturated, however, the adsorbent is a concentrated source of contaminants. Industrial applications either dump or regenerate the activated carbon. Regeneration may be accomplished in-situ or at an off-site location. In either case, concentrated contaminated waste streams must be handled appropriately to minimize environmental impact. As economic and regulatory forces drive toward minimizing waste and environmental impact, thermal catalytic oxidation is becoming more attractive. Through novel reactor and catalyst design, more complete contaminant destruction and greater resistance to poisoning can achieved leading to less waste handling, process down-time, and maintenance. Performance of a prototype thermal catalytic reactor, based on ultra-short channel monolith (USCM) catalyst substrate design, under a variety of process flow and contaminant loading conditions is discussed. The experimental results are evaluated against present and future air quality control and process gas purification processes used on board crewed spacecraft.

  2. Offsite dose calculation manual guidance: Standard radiological effluent controls for boiling water reactors

    SciTech Connect

    Meinke, W.W.; Essig, T.H.

    1991-04-01

    This report contains guidance which may be voluntarily used by licensees who choose to implement the provision of Generic Letter 89-- 01, which allows Radiological Effluent Technical Specifications (RETS) to be removed from the main body of the Technical Specifications and placed in the Offsite Dose Calculation Manual (ODCM). Guidance is provided for Standard Effluent Controls definitions, Controls for effluent monitoring instrumentation, Controls for effluent releases, Controls for radiological environmental monitoring, and the basis for Controls. Guidance on the formulation of RETS has been available in draft form for a number of years; the current effort simply recasts those RETS into Standard Radiological Effluent Controls for application to the ODCM. 11 tabs.

  3. Laser-driven fusion reactor

    DOEpatents

    Hedstrom, J.C.

    1973-10-01

    A laser-driven fusion reactor consisting of concentric spherical vessels in which the thermonuclear energy is derived from a deuterium-tritium (D + T) burn within a pellet'', located at the center of the vessels and initiated by a laser pulse. The resulting alpha -particle energy and a small fraction of the neutron energy are deposited within the pellet; this pellet energy is eventually transformed into sensible heat of lithium in a condenser outside the vessels. The remaining neutron energy is dissipated in a lithium blanket, located within the concentric vessels, where the fuel ingredient, tritium, is also produced. The heat content of the blanket and of the condenser lithium is eventually transferred to a conventional thermodynamic plant where the thermal energy is converted to electrical energy in a steam Rankine cycle. (Official Gazette)

  4. “The Marshall Rosenbluth International Summer School – 2007: Plasma Thermonuclear Fusion and Plasma Astrophysics – 2007”

    SciTech Connect

    Stefan, Vladislav Alexander

    2007-10-01

    Contents: H. Berk: Frequency Sweeping Due to Phase Space Structure Formation in Plasmas M. Campbell : The Legacy of Marshall Rosenbluth in the Development of the Laser Fusion Program in the United States J. Candy: Gyrokinetic Simulations of Fusion Plasmas P. Diamond: The Legacy of Marshall Rosenbluth in Magnetic Confinement Theory G-Y. Fu: Nonlinear Hybrid Simulations of Multiple Energetic Particle Driven Alfven Modes in Toroidal Plasmas O. Gurcan: Theory of Intrinsic Rotation and Momentum Transport V. L. Jacobs: Kinetic and Spectral Descriptions for Atomic Processes in Astrophysical and Laboratory Plasmas C. F. Kennel: Marshall Rosenbluth and Roald Sagdeev in Trieste:The Birth of Modern Space Plasma N. A. Krall: The Contribution of Marshall Rosenbluth in the Development of Plasma Drift Wave and Universal Instability Theories C. S. Liu: The Legacy of Marshall Rosenbluth in Laser-Plasma Interaction Research N. Rostoker: Plasma Physics Research With Marshall Rosenbluth - My Teacher R. Z. Sagdeev: The Legacy of Marshall Rosenbluth in Plasma Physics V. Alexander Stefan A Note on the Rosenbluth Paper: Phys. Rev. Letters, 29, 565 (1972), and the Research in Parametric Plasma Theory Thereupon J. W. Van Dam: The Role of Marshall Rosenbluth in the Development of the Thermonuclear Fusion Program in the U.S.A. E. P. Velikhov: Problems in Plasma Astrophysics R. White: The Role of Marshall Rosenbluth in the Development of the Particle and MHD Interaction in Plasmas X. Xu: Edge Gyrokinetic Theory and Continuum Simulations Marshall Nicholas ROSENBLUTH (A Brief Biography) b. February 5,1927 - Albany, New York. d. September 28, 2003 - San Diego, California. M. N. Rosenbluth, a world-acclaimed scientist, is one of the ultimate authorities in plasma and thermonuclear fusion research, often indicated by the sobriquet the "Pope of Plasma Physics." His theoretical contributions have been central to the development of controlled thermonuclear fusion. In the 1950s his pioneering work in

  5. Controller design and experiment for autothermal reforming of methanol in miniature reactor.

    PubMed

    Lu, Jiangang; Zhuang, Hong; Yang, Qinmin; Wang, Xuefei; Zheng, Jianfeng; Chen, Jinshui; Sun, Youxian

    2014-09-01

    In this paper, a miniature methanol fuel processor and its controller design is introduced for onboard hydrogen production. The hydrogen is generated via autothermal reforming of methanol. The control scheme consists of a hydrogen flow rate controller and a reforming temperature controller. To deal with uncertain system dynamics and external disturbance, an adaptive sliding mode control algorithm is adopted as the hydrogen flow rate controller for regulating hydrogen flow rate by manipulating methanol flow rate. Additionally, a high-gain observer is implemented to estimate the unmeasurable system state. The stability of closed-loop system is guaranteed by standard Lyapunov analysis. Furthermore, a variable ratio control law is employed as the reforming temperature controller to achieve steady reforming temperature by adjusting the reforming air flow rate. Finally, the effectiveness of the entire system is testified by experimental means.

  6. Advanced statistical process control of a chemical vapor tungsten deposition process on an Applied Materials Centura reactor

    NASA Astrophysics Data System (ADS)

    Stefani, Jerry A.; Poarch, Scott; Saxena, Sharad; Mozumder, P. K.

    1994-09-01

    An advanced multivariable off-line process control system, which combines traditional Statistical Process Control (SPC) with feedback control, has been applied to the CVD tungsten process on an Applied Materials Centura reactor. The goal of the model-based controller is to compensate for shifts in the process and maintain the wafer state responses on target. In the present application the controller employs measurements made on test wafers by off-line metrology tools to track the process behavior. This is accomplished by using model- bases SPC, which compares the measurements with predictions obtained from empirically-derived process models. For CVD tungsten, a physically-based modeling approach was employed based on the kinetically-limited H2 reduction of WF6. On detecting a statistically significant shift in the process, the controller calculates adjustments to the settings to bring the process responses back on target. To achieve this a few additional test wafers are processed at slightly different settings than the nominal. This local experiment allows the models to be updated to reflect the current process performance. The model updates are expressed as multiplicative or additive changes in the process inputs and a change in the model constant. This approach for model updating not only tracks the present process/equipment state, but it also provides some diagnostic capability regarding the cause of the process shift. The updated models are used by an optimizer to compute new settings to bring the responses back to target. The optimizer is capable of incrementally entering controllables into the strategy, reflecting the degree to which the engineer desires to manipulates each setting. The capability of the controller to compensate for shifts in the CVD tungsten process has been demonstrated. Targets for film bulk resistivity and deposition rate were maintained while satisfying constraints on film stress and WF6 conversion efficiency.

  7. The regulation and control strategies of a sequencing batch reactor for simultaneous nitrification and denitrification at different temperatures.

    PubMed

    Guo, Jingbo; Zhang, Lanhe; Chen, Wei; Ma, Fang; Liu, Honglei; Tian, Yu

    2013-04-01

    The performance of a sequencing batch reactor for simultaneous nitrification and denitrification (SBR-SND) was investigated under 5-30°C and strategies against temperature influences were proposed. Aeration of 8, 7, 7 and 6h were sufficient for 5±2, 10±2, 20±2 and 30±2°C, respectively. Further extension was insubstantial, only increased the aeration cost. The adjustment of C/N ratio to offset the temperature impacts was not remarkable. Prolonged sludge retention time lessened the influences of low temperature but deteriorated the system at high temperature. The oxidation reduction potential, the dissolved oxygen concentration, the sludge volume index and the extracellular polymeric substances amount changed with temperature alterations and thus affected the system performance. In conclusion, measures should be taken for temperature oscillations and the regulation and control of the operational parameters could alleviate the influences of temperature on the performances of the SBR-SND system.

  8. GOOSE, a generalized object-oriented simulation environment for developing and testing reactor models and control strategies

    SciTech Connect

    Ford, C.E.; March-Leuba, C. ); Guimaraes, L.; Ugolini, D. . Dept. of Nuclear Engineering)

    1991-01-01

    GOOSE, prototype software for a fully interactive, object-oriented simulation environment, is being developed as part of the Advanced Controls Program at Oak Ridge National Laboratory. Dynamic models may easily be constructed and tested; fully interactive capabilities allow the user to alter model parameters and complexity without recompilation. This environment provides access to powerful tools, such as numerical integration packages, graphical displays, and online help. Portability has bee an important design goal; the system was written in Objective-C in order to run on a wide variety of computers and operating systems, including UNIX workstations and personnel computers. A detailed library of nuclear reactor components, currently under development, will also be described. 5 refs., 4 figs.

  9. Immobilization of Yarrowia lipolytica lipase Ylip2 for the biocatalytic synthesis of phytosterol ester in a water activity controlled reactor.

    PubMed

    Cui, Caixia; Guan, Nan; Xing, Chen; Chen, Biqiang; Tan, Tianwei

    2016-10-01

    In this work, phytosterol ester was synthesized using Yarrowia lipolytica lipase Ylip2 that had been immobilized on inorganic support in a solvent-free system and reacted in a computer-aided water activity controlled bioreactor. The immobilization of Ylip2 on celite led to a remarkable increase in the phytosterol conversion compared to that of free lipase. An investigation of the reaction conditions were oleic acid as the fatty acid variety, 10,000U/g substrate, and a temperature of 50°C for phytosterol ester synthesis. Controlling of the water activity at a set point was accomplished by the introduction of dry air through the reaction medium at a digital feedback controlled flow rate. For the esterification of phytosterol ester, a low (15%) water activity resulted in a considerable improvement in phytosterol conversion (91.1%) as well as a decreased reaction time (78h). Furthermore, Ylip2 lipase immobilized on celite retained 90% esterification activity for the synthesis of phytosterol oleate after reused 8 cycles, while free lipase was only viable for 5 batches with 90% esterification activity remained. Finally, the phytosterol oleate space time yield increased from 1.65g/L/h with free lipase to 2.53g/L/h with immobilized lipase. These results illustrate that the immobilized Yarrowia lipolytica lipase Ylip2 in a water activity controlled reactor has great potential for the application in phytosterol esters synthesis. PMID:27416561

  10. Controlled exogenous enzyme imbibition and activation in whole chickpea seed enzyme reactor (SER).

    PubMed

    Kliger, Eynav; Fischer, Lutz; Lutz-Wahl, Sabine; Saguy, I Sam

    2011-05-01

    Chickpeas are of excellent quality (protein, vitamins, minerals, unsaturated fatty acids) and very low in phytoestrogen, making them a potentially promising source for vegetarian-based infant formula (VBIF). However, their high starch and fiber concentration could hinder their utilization for infants. To overcome this natural shortcoming, a solid-state "enzymation" (SSE) process was developed in which imbibition of exogenous enzyme facilitates hydrolysis within the intact chickpea seed. The process was termed seed enzyme reactor (SER). Liquid imbibition data of dry chickpeas during soaking were fitted with the Weibull distribution model. The derived Weibull shape parameter, β, value (0.77 ± 0.11) indicated that the imbibition mechanism followed Fickian diffusion. Imbibition occurred through the coat and external layers. The process was tested using green fluorescent protein (GFP) as an exogenous marker, and involved soaking, thermal treatment, peeling, microwave partial drying, rehydration in enzyme solution, and SSE at an adjusted pH, time, and temperature. Amylases, or a combination of amylases and cellulases, resulted in significant carbohydrate hydrolysis (23% and 47% of the available starch, respectively). In addition, chickpea initial raffinose and stachyose concentration was significantly reduced (91% and 92%, respectively). The process could serve as a proof of concept, requiring additional development and optimization to become a full industrial application.

  11. Nuclear Criticality Control and Safety of Plutonium-Uranium Fuel Mixtures Outside Reactors

    SciTech Connect

    Biswas, D; Mennerdahl, D

    2008-06-23

    The ANSI/ANS 8.12 standard was first approved in July 1978. At that time, this edition was applicable to operations with plutonium-uranium oxide (MOX) fuel mixtures outside reactors and was limited to subcritical limits for homogeneous systems. The next major revision, ANSI/ANS-8.12-1987, included the addition of subcritical limits for heterogeneous systems. The standard was subsequently reaffirmed in February 1993. During late 1990s, substantial work was done by the ANS 8.12 Standard Working Group to re-examine the technical data presented in the standard using the latest codes and cross section sets. Calculations performed showed good agreement with the values published in the standard. This effort resulted in the reaffirmation of the standard in March 2002. The standard is currently in a maintenance mode. After 2002, activities included discussions to determine the future direction of the standard and to follow the MOX standard development by the International Standard Organization (ISO). In 2007, the Working Group decided to revise the standard to extend the areas of applicability by providing a wider range of subcritical data. The intent is to cover a wider domain of MOX fuel fabrication and operations. It was also decided to follow the ISO MOX standard specifications (related to MOX density and isotopics) and develop a new set of subcritical limits for homogeneous systems. This has resulted in the submittal (and subsequent approval) of the project initiation notification system form (PINS) in 2007.

  12. NEUTRONIC REACTOR

    DOEpatents

    Wade, E.J.

    1958-09-16

    This patent relates to a reflector means for a neutronic reactor. A reflector comprised of a plurality of vertically movable beryllium control members is provided surrounding the sides of the reactor core. An absorber of fast neutrons comprised of natural uramum surrounds the reflector. An absorber of slow neutrons surrounds the absorber of fast neutrons and is formed of a plurality of beryllium blocks having natural uranium members distributcd therethrough. in addition, a movable body is positioned directly below the core and is comprised of a beryllium reflector and an absorbing member attached to the botiom thereof, the absorbing member containing a substance selected from the goup consisting of natural urantum and Th/sup 232/.

  13. a New Approach of the Deflagration to Detonation Transition in SNIa Thermonuclear Supernovae

    NASA Astrophysics Data System (ADS)

    Chièze, Jean Pierre; Charignon, Camille

    2015-03-01

    A wide class of type Ia thermonuclear supernovae models relies on the transition from the subsonic deflagration combustion regime to the supersonic detonation regime of the carbon and oxygen mixture of an accreting white dwarf, near the Chandrasekhar mass. We show that this can actually be achieved in a cold C+O white dwarf near the Chandrasekhar mass, with seed sound waves of relatively low Mach number M ˜ 0.02. Moreover, even weaker perturbations, with velocity perturbations as low as M ˜ 0.003 can trigger a detonation wave in SNIa progenitors models wich include the presence of a thin helium surface layer.

  14. Fermi-GBM detection of a thermonuclear burst from 4U 1608-52

    NASA Astrophysics Data System (ADS)

    Jenke, P.; Linares, M.; Connaughton, V.; van der Horst, A. J.; Camero-Arranz, A.; Finger, M.; Wilson-Hodge, C.; Kouveliotou, C.

    2012-05-01

    We report the detection with Fermi-GBM (daily CTIME data, 12-25 keV band) of an X-ray burst from a location consistent with the neutron star low-mass X-ray binary and thermonuclear burster 4U 1608-52. The burst peak occurred on May 2, 2012 at 06:47:54 UTC. The Fermi-GBM location of the burst is R.A.(J2000) = 241.3 deg, DEC(J2000) = -51.1 deg (1.8 deg from 4U 1608-52) with a 1 sigma error of 4.7 deg.

  15. Development of tools for safety analysis of control software in advanced reactors

    SciTech Connect

    Guarro, S.; Yau, M.; Motamed, M.

    1996-04-01

    Software based control systems have gained a pervasive presence in a wide variety of applications, including nuclear power plant control and protection systems which are within the oversight and licensing responsibility of the US Nuclear Regulatory Commission. While the cost effectiveness and flexibility of software based plant process control is widely recognized, it is very difficult to achieve and prove high levels of demonstrated dependability and safety assurance for the functions performed by process control software, due to the very flexibility and potential complexity of the software itself. The development of tools to model, analyze and test software design and implementations in the context of the system that the software is designed to control can greatly assist the task of providing higher levels of assurance than those obtainable by software testing alone. This report presents and discusses the development of the Dynamic Flowgraph Methodology (DFM) and its application in the dependability and assurance analysis of software-based control systems. The features of the methodology and full-scale examples of application to both generic process and nuclear power plant control systems are presented and discussed in detail. The features of a workstation software tool developed to assist users in the application of DFM are also described.

  16. Model reduction and temperature uniformity control for rapid thermal chemical vapor deposition reactors

    NASA Astrophysics Data System (ADS)

    Theodoropoulou, Artemis-Georgia

    The consideration of Rapid Thermal Processing (RTP) in semiconductor manufacturing has recently been increasing. As a result, control of RTP systems has become of great importance since it is expected to help in addressing uniformity problems that, so far, have been obstructing the acceptance of the method. The spatial distribution appearing in RTP models necessitates the use of model reduction in order to obtain models of a size suitable for use in control algorithms. This dissertation addresses model reduction as well as control issues for RTP systems. A model of a three-zone Rapid Thermal Chemical Vapor Deposition (RTCVD) system is developed to study the effects of spatial wafer temperature patterns on polysilicon deposition uniformity. A sequence of simulated runs is performed, varying the lamp power profiles so that different wafer temperature modes are excited. The dominant spatial wafer thermal modes are extracted via Proper Orthogonal Decomposition and subsequently used as a set of trial functions to represent both the wafer temperature and deposition thickness. A collocation formulation of Galerkin's method is used to discretize the original modeling equations, giving a low-order model which loses little of the original, high-order model's fidelity. We make use of the excellent predictive capabilities of the reduced model to optimize power inputs to the lamp banks to achieve a desired polysilicon deposition thickness at the end of a run with minimal deposition spatial nonuniformity. Since the results illustrate that the optimization procedure benefits from the use of the reduced-order model, we further utilize the reduced order model for real time Model Based Control. The feedback controller is designed using the Internal Model Control (IMC) structure especially modified to handle systems described by ordinary differential and algebraic equations. The IMC controller is obtained using optimal control theory on singular arcs extended for multi input systems

  17. A high energy neutral beam system for reactors

    SciTech Connect

    Anderson, O.A.; Chan, C.F.; Cooper, W.S.; Leung, K.N.; Lietzke, A.F.; Kim, C.H.; Kunkel, W.B.; Kwan, J.W.; Purgalis, P.; Schlachter, A.S.

    1988-09-01

    High energy neutral beams provide a promising method of heating and driving current in steady-state tokamak fusion reactors. As an example, we have made a conceptual design of a neutral beam system for current drive on the International Thermonuclear Experimental Reactor (ITER). The system, based on electrostatic acceleration of D/sup /minus// ions, can deliver up to 100 MW of 1.6 MeV D/sup 0/ neutrals through three ports. Radiation protection is provided by locating sensitive beamline components 35 to 50 m from the reactor. In an application to a 3300 MW power reactor, a system delivering 120 MW of 2-2.4 MeV deuterium beams assisted by 21 MW of lower hybrid wave power drives 25 MA and provides an adequate plasma power gain (Q = 24) for a commercial fusion power plant. 8 refs., 1 fig., 2 tabs.

  18. THE RETURN OF THE BURSTS: THERMONUCLEAR FLASHES FROM CIRCINUS X-1

    SciTech Connect

    Linares, M.; Homan, J.; Chakrabarty, D.; Watts, A.; Altamirano, D.; Degenaar, N.; Yang, Y.; Wijnands, R.; Armas-Padilla, M.; Cavecchi, Y.; Kalamkar, M.; Kaur, R.; Patruno, A.; Van der Klis, M.; Soleri, P.; Casella, P.; Rea, N.

    2010-08-10

    We report the detection of 15 X-ray bursts with RXTE and Swift observations of the peculiar X-ray binary Circinus X-1 (Cir X-1) during its 2010 May X-ray re-brightening. These are the first X-ray bursts observed from the source after the initial discovery by Tennant and collaborators, 25 years ago. By studying their spectral evolution, we firmly identify nine of the bursts as type I (thermonuclear) X-ray bursts. We obtain an arcsecond location of the bursts that confirms once and for all the identification of Cir X-1 as a type I X-ray burst source, and therefore as a low magnetic field accreting neutron star. The first five bursts observed by RXTE are weak and show approximately symmetric light curves, without detectable signs of cooling along the burst decay. We discuss their possible nature. Finally, we explore a scenario to explain why Cir X-1 shows thermonuclear bursts now but not in the past, when it was extensively observed and accreting at a similar rate.

  19. Determination of controlling earthquakes from probabilistic seismic hazard analysis for nuclear reactor sites

    SciTech Connect

    Boissonnade, A.; Bernreuter, D.; Chokshi, N.; Murphy, A.

    1995-04-04

    Recently, the US Nuclear Regulatory Commission published, for public comments, a revision to 10 CFR Part 100. The proposed regulation acknowledges that uncertainties are inherent in estimates of the Safe Shutdown Earthquake Ground Motion (SSE) and requires that these uncertainties be addressed through an appropriate analysis. One element of this evaluation is the assessment of the controlling earthquake through the probabilistic seismic hazard analysis (PSHA) and its use in determining the SSE. This paper reviews the basis for the various key choices in characterizing the controlling earthquake.

  20. Plasma-material Interactions in Current Tokamaks and their Implications for Next-step Fusion Reactors

    SciTech Connect

    Federici, G.; Skinner, C.H.; Brooks, J.N.; Coad, J.P.; Grisolia, C.

    2001-01-10

    The major increase in discharge duration and plasma energy in a next-step DT [deuterium-tritium] fusion reactor will give rise to important plasma-material effects that will critically influence its operation, safety, and performance. Erosion will increase to a scale of several centimeters from being barely measurable at a micron scale in today's tokamaks. Tritium co-deposited with carbon will strongly affect the operation of machines with carbon plasma-facing components. Controlling plasma wall interactions is critical to achieving high performance in present-day tokamaks and this is likely to continue to be the case in the approach to practical fusion reactors. Recognition of the important consequences of these phenomena has stimulated an internationally coordinated effort in the field of plasma-surface interactions supporting the Engineering Design Activities of the International Thermonuclear Experimental Reactor (ITER) project and significant progress has been made in better under standing these issues. This paper reviews the underlying physical processes and the existing experimental database of plasma-material interactions both in tokamaks and laboratory simulation facilities for conditions of direct relevance to next-step fusion reactors. Two main topical groups of interactions are considered: (i) erosion/redeposition from plasma sputtering and disruptions, including dust and flake generation, (ii) tritium retention and removal. The use of modeling tools to interpret the experimental results and make projections for conditions expected in future devices is explained. Outstanding technical issues and specific recommendations on potential R and D [Research and Development] avenues for their resolution are presented.

  1. Nuclear Technology Series. Course 6: Instrumentation and Control of Reactors and Plant Systems.

    ERIC Educational Resources Information Center

    Center for Occupational Research and Development, Inc., Waco, TX.

    This technical specialty course is one of thirty-five courses designed for use by two-year postsecondary institutions in five nuclear technician curriculum areas: (1) radiation protection technician, (2) nuclear instrumentation and control technician, (3) nuclear materials processing technician, (4) nuclear quality-assurance/quality-control…

  2. The TDF System for Thermonuclear Plasma Reaction Rates, Mean Energies and Two-Body Final State Particle Spectra

    SciTech Connect

    Warshaw, S I

    2001-07-11

    The rate of thermonuclear reactions in hot plasmas as a function of local plasma temperature determines the way in which thermonuclear ignition and burning proceeds in the plasma. The conventional model approach to calculating these rates is to assume that the reacting nuclei in the plasma are in Maxwellian equilibrium at some well-defined plasma temperature, over which the statistical average of the reaction rate quantity {sigma}v is calculated, where {sigma} is the cross-section for the reaction to proceed at the relative velocity v between the reacting particles. This approach is well-understood and is the basis for much nuclear fusion and astrophysical nuclear reaction rate data. The Thermonuclear Data File (TDF) system developed at the Lawrence Livermore National Laboratory (Warshaw 1991), which is the topic of this report, contains data on the Maxwellian-averaged thermonuclear reaction rates for various light nuclear reactions and the correspondingly Maxwellian-averaged energy spectra of the particles in the final state of those reactions as well. This spectral information closely models the output particle and energy distributions in a burning plasma, and therefore leads to more accurate computational treatments of thermonuclear burn, output particle energy deposition and diagnostics, in various contexts. In this report we review and derive the theoretical basis for calculating Maxwellian-averaged thermonuclear reaction rates, mean particle energies, and output particle spectral energy distributions for these reactions in the TDF system. The treatment of the kinematics is non-relativistic. The current version of the TDF system provides exit particle energy spectrum distributions for two-body final state reactions only. In a future report we will discuss and describe how output particle energy spectra for three- and four-body final states can be developed for the TDF system. We also include in this report a description of the algorithmic implementation of the

  3. HOMOGENEOUS NUCLEAR POWER REACTOR

    DOEpatents

    King, L.D.P.

    1959-09-01

    A homogeneous nuclear power reactor utilizing forced circulation of the liquid fuel is described. The reactor does not require fuel handling outside of the reactor vessel during any normal operation including complete shutdown to room temperature, the reactor being selfregulating under extreme operating conditions and controlled by the thermal expansion of the liquid fuel. The liquid fuel utilized is a uranium, phosphoric acid, and water solution which requires no gus exhaust system or independent gas recombining system, thereby eliminating the handling of radioiytic gas.

  4. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Zinn, W.H.; Anderson, H.L.

    1958-09-16

    Means are presenied for increasing the reproduction ratio of a gaphite- moderated neutronic reactor by diminishing the neutron loss due to absorption or capture by gaseous impurities within the reactor. This means comprised of a fluid-tight casing or envelope completely enclosing the reactor and provided with a valve through which the casing, and thereby the reactor, may be evacuated of atmospheric air.

  5. Modelling of biofilm reactors

    SciTech Connect

    Rodrigues, A.; Grasmick, A.; Elmaleh, S.

    1982-10-01

    Comprehensive models of biofilm reactors are developed. Model I assumes a zero-order reaction of a limiting substrate and a diffusional mass transport through the biofilm; in the diffusion-controlled regime the model is fully characterized by one parameter alpha. From this model the conversion of substrate or reactor efficiency can be calculated, for continuously stirred tank reactors (CSTRs) and plug flow reactors respectively, as follows: EA = )alpha(alpha + 2)) 1/2 - alpha; and Ep = (2 alpha) 1/2 - alpha/2: Validation of the model is tested for different experimental systems. Model II includes liquid film mass transfer resistance. The conversion gap between plug flow reactors and CSTRs is always lower than 25% and, as a first approximation, the biofilm reactor design does not then require accurate residence time distribution measurements. (Refs. 23).

  6. Materials issues in fusion reactors

    NASA Astrophysics Data System (ADS)

    Suri, A. K.; Krishnamurthy, N.; Batra, I. S.

    2010-02-01

    The world scientific community is presently engaged in one of the toughest technological tasks of the current century, namely, exploitation of nuclear fusion in a controlled manner for the benefit of mankind. Scientific feasibility of controlled fusion of the light elements in plasma under magnetic confinement has already been proven. International efforts in a coordinated and co-operative manner are presently being made to build ITER - the International Thermonuclear Experimental Reactor - to test, in this first step, the concept of 'Tokamak' for net fusion energy production. To exploit this new developing option of making energy available through the route of fusion, India too embarked on a robust fusion programme under which we now have a working tokamak - the Aditya and a steady state tokamak (SST-1), which is on the verge of functioning. The programme envisages further development in terms of making SST-2 followed by a DEMO and finally the fusion power reactor. Further, with the participation of India in the ITER program in 2005, and recent allocation of half - a - port in ITER for placing our Lead - Lithium Ceramic Breeder (LLCB) based Test Blanket Module (TBM), meant basically for breeding tritium and extracting high grade heat, the need to understand and address issues related to materials for these complex systems has become all the more necessary. Also, it is obvious that with increasing power from the SST stages to DEMO and further to PROTOTYPE, the increasing demands on performance of materials would necessitate discovery and development of new materials. Because of the 14.1 MeV neutrons that are generated in the D+T reaction exploited in a tokamak, the materials, especially those employed for the construction of the first wall, the diverter and the blanket segments, suffer crippling damage due to the high He/dpa ratios that result due to the high energy of the neutrons. To meet this challenge, the materials that need to be developed for the tokamaks

  7. Joint System Prognostics For Increased Efficiency And Risk Mitigation In Advanced Nuclear Reactor Instrumentation and Control

    SciTech Connect

    Donald D. Dudenhoeffer; Tuan Q. Tran; Ronald L. Boring; Bruce P. Hallbert

    2006-08-01

    The science of prognostics is analogous to a doctor who, based on a set of symptoms and patient tests, assesses a probable cause, the risk to the patient, and a course of action for recovery. While traditional prognostics research has focused on the aspect of hydraulic and mechanical systems and associated failures, this project will take a joint view in focusing not only on the digital I&C aspect of reliability and risk, but also on the risks associated with the human element. Model development will not only include an approximation of the control system physical degradation but also on human performance degradation. Thus the goal of the prognostic system is to evaluate control room operation; to identify and potentially take action when performance degradation reduces plant efficiency, reliability or safety.

  8. An experimental study for biological nitrogen removal and control strategies in a sequencing batch reactor (SBR).

    PubMed

    Manga, J; Venegas, C; Palma-Acosta, M J; Abad, D

    2007-07-01

    The aim of this work is to present an overview about an experimental study for biological nitrogen removal implemented in a pilot-scale plant, located in the Universidad Del Norte in Barranquilla, Colombia. This plant was studied in two different periods. The first period, which was carried out in 90 days, was dedicated to study the influence of the daily variations on the influent and effluent wastewater, and prove some control routines for nitrogen removal. In the second period, which was carried out in 120 days, the removal process was optimized with the addition of acetic acid as an external carbon source, and the implementation of the final control strategy was performed based on the results of the previous period.

  9. An experimental study for biological nitrogen removal and control strategies in a sequencing batch reactor (SBR).

    PubMed

    Manga, J; Venegas, C; Palma-Acosta, M J; Abad, D

    2007-07-01

    The aim of this work is to present an overview about an experimental study for biological nitrogen removal implemented in a pilot-scale plant, located in the Universidad Del Norte in Barranquilla, Colombia. This plant was studied in two different periods. The first period, which was carried out in 90 days, was dedicated to study the influence of the daily variations on the influent and effluent wastewater, and prove some control routines for nitrogen removal. In the second period, which was carried out in 120 days, the removal process was optimized with the addition of acetic acid as an external carbon source, and the implementation of the final control strategy was performed based on the results of the previous period. PMID:17674653

  10. Strategic Application of Residence-Time Control in Continuous-Flow Reactors

    PubMed Central

    Mándity, István M; Ötvös, Sándor B; Fülöp, Ferenc

    2015-01-01

    As a sustainable alternative for conventional batch-based synthetic techniques, the concept of continuous-flow processing has emerged in the synthesis of fine chemicals. Systematic tuning of the residence time, a key parameter of continuous-reaction technology, can govern the outcome of a chemical reaction by determining the reaction rate and the conversion and by influencing the product selectivity. This review furnishes a brief insight into flow reactions in which high chemo- and/or stereoselectivity can be attained by strategic residence-time control and illustrates the importance of the residence time as a crucial parameter in sustainable method development. Such a fine reaction control cannot be performed in conventional batch reaction set-ups. PMID:26246983

  11. A rule-based expert system for automatic control rod pattern generation for boiling water reactors

    SciTech Connect

    Lin, L.S.; Lin, C. )

    1991-07-01

    This paper reports on an expert system for generating control rod patterns that has been developed. The knowledge is transformed into IF-THEN rules. The inference engine uses the Rete pattern matching algorithm to match facts, and rule premises and conflict resolution strategies to make the system function intelligently. A forward-chaining mechanism is adopted in the inference engine. The system is implemented in the Common Lisp programming language. The three-dimensional core simulation model performs the core status and burnup calculations. The system is successfully demonstrated by generating control rod programming for the 2894-MW (thermal) Kuosheng nuclear power plant in Taiwan. The computing time is tremendously reduced compared to programs using mathematical methods.

  12. On the optimal control of fed-batch reactors with substrate-inhibited kinetics.

    PubMed

    Cazzador, L

    1988-05-01

    The optimal feed rate profiles, for fed-batch fermentation that maximizes the biomass production and accounts for time, are analyzed. The solution can be found only if the final arc of the optimal control is a batch arc, since in this case the final concentrations of substrate and biomass can be determined by ulterior conditions on the mass balance and on the final growth rate of biomass and thus it is possible to solve the resulting time optimal problem by using Green's theorem. This evidences the "turnpike property" of the solution, which tries to spend the maximum time on or at least near the singular arc along which the substrate concentration is maintained constant. The optimality of the final batch arc is related to the time operational cost in the performance index. The sequence of the control depends on the initial conditions for which six different regions, with the respective patterns, have been identified, in case the performance index allows the control sequence to have a final batch.

  13. Advanced light water reactor requirements document: Chapter 4, Reactor systems

    SciTech Connect

    Not Available

    1987-06-01

    The purpose of this chapter of the Advanced Light Water Reactor (ALWR) Plant Requirements Document is to establish utility requirements for the design of the Reactor Systems of Advanced LWR plants consistent with the objectives and principles of the ALWR program. The scope of this chapter covers the following for Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR): reactor pressure vessel, nozzles and safe-ends, reactor internals, in-vessel portions of fluid systems (including reactor internal pumps (Emergency Core Cooling System (ECCS) piping and spargers), nuclear fuel, and the control rods and control rod drive system (including hydraulic supply and accumulators). Special tools required for reactor system maintenance, inspection and testing are also covered.

  14. Biogeochemical control on groundwater arsenic contamination - a laboratory batch reactor approach

    NASA Astrophysics Data System (ADS)

    Maguffin, S. C.; Jin, Q.

    2011-12-01

    Microbial metabolism plays an important role in groundwater arsenic contamination, but how microbial metabolisms impact arsenic levels and mobility in groundwater is not well understood. This study takes the bedrock aquifer of the Willamette Basin, Oregon as an example and examines potential microbial metabolisms and their impact on groundwater arsenic chemistry using sediment slurry experiments. The slurries were prepared using aquifer sediments and artificial groundwater and included 1) a sterile control, 2) slurries with in situ aquifer conditions, 3) slurries amended with ethanol as an electron donor, and 4) slurries with the addition of ethanol and sulfate. The slurries were incubated at in situ temperature for two months. Aqueous and gas samples were collected to monitor chemical compositions of the slurries; sediments were sampled for enumerating microbial functional groups using the most probable number method and for analyzing solid-phase iron, sulfide, and arsenic. The results suggest the presence of a complex biogeochemical reaction network in the aquifer; this network consists of microbial iron reduction, arsenate reduction, sulfate reduction, and methanogenesis. These metabolisms can occur simultaneously in the aquifer, controlling groundwater arsenic speciation and concentrations. The results also offer new insights into the thermodynamic favorability of microbial reduction of iron and arsenate as well as the potential of arsenic detoxification in aquifers.

  15. NEUTRONIC REACTOR SYSTEM

    DOEpatents

    Treshow, M.

    1959-02-10

    A reactor system incorporating a reactor of the heterogeneous boiling water type is described. The reactor is comprised essentially of a core submerged adwater in the lower half of a pressure vessel and two distribution rings connected to a source of water are disposed within the pressure vessel above the reactor core, the lower distribution ring being submerged adjacent to the uppcr end of the reactor core and the other distribution ring being located adjacent to the top of the pressure vessel. A feed-water control valve, responsive to the steam demand of the load, is provided in the feedwater line to the distribution rings and regulates the amount of feed water flowing to each distribution ring, the proportion of water flowing to the submerged distribution ring being proportional to the steam demand of the load. This invention provides an automatic means exterior to the reactor to control the reactivity of the reactor over relatively long periods of time without relying upon movement of control rods or of other moving parts within the reactor structure.

  16. Spreading of thermonuclear flames on the neutron star in SAX J1808.4-3658: an observational tool

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, Sudip; Strohmayer, Tod E.

    2005-01-01

    We analyse archival Rossi X-Ray Timing Explorer (RXTE) proportional counter array (PCA) data of thermonuclear X-ray bursts from the 2002 outburst of the accreting millisecond pulsar SAX 51808.4-3658. We present evidence of a complex frequency modulation of oscillations during burst rise, and correlations among the time evolution of the oscillation frequency, amplitude, and the inferred burning region area. We discuss these findings in the context of a model, based on thermonuclear flame spreading on the neutron star surface, that can qualitatively explain these features. From our model, we infer that for the 2002 Oct. 15 thermonuclear burst, the ignition likely occurred in the mid-latitudes, the burning region took approx. 0.2 s to nearly encircle the equatorial region of the neutron star, and after that the lower amplitude oscillation originated from the remaining asymmetry of the burning front in the same hemisphere where the burst ignited. We emphasize that studies of the evolution of burst oscillation properties during burst rise can provide a powerful tool to understand thermonuclear flame spreading on neutron star surfaces under extreme physical conditions.

  17. A virtual control room with an embedded, interactive nuclear reactor simulator

    SciTech Connect

    Markidis, S.; Rizwan, U.

    2006-07-01

    The use of virtual nuclear control room can be an effective and powerful tool for training personnel working in the nuclear power plants. Operators could experience and simulate the functioning of the plant, even in critical situations, without being in a real power plant or running any risk. 3D models can be exported to Virtual Reality formats and then displayed in the Virtual Reality environment providing an immersive 3D experience. However, two major limitations of this approach are that 3D models exhibit static textures, and they are not fully interactive and therefore cannot be used effectively in training personnel. In this paper we first describe a possible solution for embedding the output of a computer application in a 3D virtual scene, coupling real-world applications and VR systems. The VR system reported here grabs the output of an application running on an X server; creates a texture with the output and then displays it on a screen or a wall in the virtual reality environment. We then propose a simple model for providing interaction between the user in the VR system and the running simulator. This approach is based on the use of internet-based application that can be commanded by a laptop or tablet-pc added to the virtual environment. (authors)

  18. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, J.

    1996-03-19

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

  19. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, Juhani

    1996-01-01

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

  20. Design, performance, and grounding aspects of the International Thermonuclear Experimental Reactor ion cyclotron range of frequencies antenna

    SciTech Connect

    Durodié, F. Dumortier, P.; Vrancken, M.; Messiaen, A.; Huygen, S.; Louche, F.; Van Schoor, M.; Vervier, M.; Winkler, K.

    2014-06-15

    ITER's Ion Cyclotron Range of Frequencies (ICRF) system [Lamalle et al., Fusion Eng. Des. 88, 517–520 (2013)] comprises two antenna launchers designed by CYCLE (a consortium of European associations listed in the author affiliations above) on behalf of ITER Organisation (IO), each inserted as a Port Plug (PP) into one of ITER's Vacuum Vessel (VV) ports. Each launcher is an array of 4 toroidal by 6 poloidal RF current straps specified to couple up to 20 MW in total to the plasma in the frequency range of 40 to 55 MHz but limited to a maximum system voltage of 45 kV and limits on RF electric fields depending on their location and direction with respect to, respectively, the torus vacuum and the toroidal magnetic field. A crucial aspect of coupling ICRF power to plasmas is the knowledge of the plasma density profiles in the Scrape-Off Layer (SOL) and the location of the RF current straps with respect to the SOL. The launcher layout and details were optimized and its performance estimated for a worst case SOL provided by the IO. The paper summarizes the estimated performance obtained within the operational parameter space specified by IO. Aspects of the RF grounding of the whole antenna PP to the VV port and the effect of the voids between the PP and the Blanket Shielding Modules (BSM) surrounding the antenna front are discussed. These blanket modules, whose dimensions are of the order of the ICRF wavelengths, together with the clearance gaps between them will constitute a corrugated structure which will interact with the electromagnetic waves launched by ICRF antennas. The conditions in which the grooves constituted by the clearance gaps between the blanket modules can become resonant are studied. Simple analytical models and numerical simulations show that mushroom type structures (with larger gaps at the back than at the front) can bring down the resonance frequencies, which could lead to large voltages in the gaps between the blanket modules and perturb the RF properties of the antenna if they are in the ICRF operating range. The effect on the wave propagation along the wall structure, which is acting as a spatially periodic (toroidally and poloidally) corrugated structure, and hence constitutes a slow wave structure modifying the wall boundary condition, is examined.

  1. Design, performance, and grounding aspects of the International Thermonuclear Experimental Reactor ion cyclotron range of frequencies antenna

    NASA Astrophysics Data System (ADS)

    Durodié, F.; Dumortier, P.; Vrancken, M.; Messiaen, A.; Bamber, R.; Hancock, D.; Huygen, S.; Lockley, D.; Louche, F.; Maggiora, R.; Milanesio, D.; Nightingale, M. P. S.; Shannon, M.; Tigwell, P.; Van Schoor, M.; Vervier, M.; Wilson, D.; Winkler, K.

    2014-06-01

    ITER's Ion Cyclotron Range of Frequencies (ICRF) system [Lamalle et al., Fusion Eng. Des. 88, 517-520 (2013)] comprises two antenna launchers designed by CYCLE (a consortium of European associations listed in the author affiliations above) on behalf of ITER Organisation (IO), each inserted as a Port Plug (PP) into one of ITER's Vacuum Vessel (VV) ports. Each launcher is an array of 4 toroidal by 6 poloidal RF current straps specified to couple up to 20 MW in total to the plasma in the frequency range of 40 to 55 MHz but limited to a maximum system voltage of 45 kV and limits on RF electric fields depending on their location and direction with respect to, respectively, the torus vacuum and the toroidal magnetic field. A crucial aspect of coupling ICRF power to plasmas is the knowledge of the plasma density profiles in the Scrape-Off Layer (SOL) and the location of the RF current straps with respect to the SOL. The launcher layout and details were optimized and its performance estimated for a worst case SOL provided by the IO. The paper summarizes the estimated performance obtained within the operational parameter space specified by IO. Aspects of the RF grounding of the whole antenna PP to the VV port and the effect of the voids between the PP and the Blanket Shielding Modules (BSM) surrounding the antenna front are discussed. These blanket modules, whose dimensions are of the order of the ICRF wavelengths, together with the clearance gaps between them will constitute a corrugated structure which will interact with the electromagnetic waves launched by ICRF antennas. The conditions in which the grooves constituted by the clearance gaps between the blanket modules can become resonant are studied. Simple analytical models and numerical simulations show that mushroom type structures (with larger gaps at the back than at the front) can bring down the resonance frequencies, which could lead to large voltages in the gaps between the blanket modules and perturb the RF properties of the antenna if they are in the ICRF operating range. The effect on the wave propagation along the wall structure, which is acting as a spatially periodic (toroidally and poloidally) corrugated structure, and hence constitutes a slow wave structure modifying the wall boundary condition, is examined.

  2. Formation and sustainment of internal transport barriers in the International Thermonuclear Experimental Reactor with the baseline heating mix

    SciTech Connect

    Poli, Francesca M.; Kessel, Charles E.

    2013-05-15

    Plasmas with internal transport barriers (ITBs) are a potential and attractive route to steady-state operation in ITER. These plasmas exhibit radially localized regions of improved confinement with steep pressure gradients in the plasma core, which drive large bootstrap current and generate hollow current profiles and negative magnetic shear. This work examines the formation and sustainment of ITBs in ITER with electron cyclotron heating and current drive. The time-dependent transport simulations indicate that, with a trade-off of the power delivered to the equatorial and to the upper launcher, the sustainment of steady-state ITBs can be demonstrated in ITER with the baseline heating configuration.

  3. The structure and thermal properties of plasma-sprayed beryllium for the International Thermonuclear Experimental Reactor (ITER)

    SciTech Connect

    Castro, R.G.; Bartlett, A.; Elliott, K.E.; Hollis, K.J.

    1996-09-01

    Plasma spraying is being studied for in situ repair of damaged Be and W plasma facing surfaces for ITER, the next generation magnetic fusion energy device, and is also being considered for fabricating Be and W plasma-facing components for the first wall of ITER. Investigators at LANL`s Beryllium Atomization and Thermal Spray Facility have concentrated on investigating the structure-property relation between as-deposited microstructures of plasma sprayed Be coatings and resulting thermal properties. In this study, the effect of initial substrate temperature on resulting thermal diffusivity of Be coatings and the thermal diffusivity at the coating/Be substrate interface (interface thermal resistance) was investigated. Results show that initial Be substrate temperatures above 600 C can improve the thermal diffusivity of the Be coatings and minimize any thermal resistance at the interface between the Be coating and Be substrate.

  4. Microlith-Based Catalytic Reactor for Air Quality and Trace Contaminant Control Applications

    NASA Technical Reports Server (NTRS)

    Vilekar, Saurabh; Hawley, Kyle; Junaedi, Christian; Crowder, Bruce; Prada, Julian; Mastanduno, Richard; Perry, Jay L.; Kayatin, Matthew J.

    2015-01-01

    Traditionally, gaseous compounds such as methane, carbon monoxide, and trace contaminants have posed challenges for maintaining clean air in enclosed spaces such as crewed spacecraft cabins as they are hazardous to humans and are often difficult to remove by conventional adsorption technology. Catalytic oxidizers have provided a reliable and robust means of disposing of even trace levels of these compounds by converting them into carbon dioxide and water. Precision Combustion, Inc. (PCI) and NASA - Marshall (MSFC) have been developing, characterizing, and optimizing high temperature catalytic oxidizers (HTCO) based on PCI's patented Microlith® technology to meet the requirements of future extended human spaceflight explorations. Current efforts have focused on integrating the HTCO unit with a compact, simple recuperative heat exchanger to reduce the overall system size and weight while also reducing its energy requirements. Previous efforts relied on external heat exchangers to recover the waste heat and recycle it to the oxidizer to minimize the system's power requirements; however, these units contribute weight and volume burdens to the overall system. They also result in excess heat loss due to the separation of the HTCO and the heat recuperator, resulting in lower overall efficiency. Improvements in the recuperative efficiency and close coupling of HTCO and heat recuperator lead to reductions in system energy requirements and startup time. Results from testing HTCO units integrated with heat recuperators at a variety of scales for cabin air quality control and heat melt compactor applications are reported and their benefits over previous iterations of the HTCO and heat recuperator assembly are quantified in this paper.

  5. Plasma physics effects on thermonuclear burn rate in the presence of hydrodynamic mix

    NASA Astrophysics Data System (ADS)

    Tang, Xian-Zhu; Guo, Zehua; Kagan, Grigory; McDevitt, Christopher; Srinivasan, Bhuvana

    2016-03-01

    Hydrodynamic mix can significantly degrade thermonuclear burn rate in an inertial confinement fusion (ICF) target. Successful mitigation requires a detailed understanding of the physical mechanisms by which mix affects burn. Here we summarize the roles of three distinct plasma physics effects on burn rate. The first is the well-known effect of enhanced thermal energy loss from the hot spot and the mitigating role of self-generated or externally-applied magnetic field. The second is the fuel ion separation via inter-species ion diffusion driven by the powerful thermodynamic forces exacerbated by mix during the implosion process. The third is the fusion reactivity modification by fast ion transport in a mix-dominated ICF target, where hot plasma is intermingled with cold fuel.

  6. Stellar dynamics. The fastest unbound star in our Galaxy ejected by a thermonuclear supernova.

    PubMed

    Geier, S; Fürst, F; Ziegerer, E; Kupfer, T; Heber, U; Irrgang, A; Wang, B; Liu, Z; Han, Z; Sesar, B; Levitan, D; Kotak, R; Magnier, E; Smith, K; Burgett, W S; Chambers, K; Flewelling, H; Kaiser, N; Wainscoat, R; Waters, C

    2015-03-01

    Hypervelocity stars (HVSs) travel with velocities so high that they exceed the escape velocity of the Galaxy. Several acceleration mechanisms have been discussed. Only one HVS (US 708, HVS 2) is a compact helium star. Here we present a spectroscopic and kinematic analysis of US 708. Traveling with a velocity of ~1200 kilometers per second, it is the fastest unbound star in our Galaxy. In reconstructing its trajectory, the Galactic center becomes very unlikely as an origin, which is hardly consistent with the most favored ejection mechanism for the other HVSs. Furthermore, we detected that US 708 is a fast rotator. According to our binary evolution model, it was spun-up by tidal interaction in a close binary and is likely to be the ejected donor remnant of a thermonuclear supernova. PMID:25745168

  7. Astrophysics Simulations from the ASC/Alliances Center for Astrophysical Thermonuclear Flashes

    DOE Data Explorer

    The "Flash Center" works to solve the long-standing problem of thermonuclear flashes on the surfaces of compact stars such as neutron stars and white dwarfs, and in the interior of white dwarfs (i.e., Type I supernovae). The physical conditions, and many of the physical phenomena, are similar to those confronted by the Department of Energy Stockpile Stewardship program. The (fully ionized) plasmas are at very high temperatures and densities; and the physical problems of nuclear ignition, deflagration or detonation, turbulent mixing, and interface dynamics for complex multicomponent fluids are common to the weapons program. Because virtually every aspect of this problem represents a computational Grand Challenge, large-scale numerical simulations are at the heart of its resolution (Taken from Executive Summary page). More than 35 simulations and computer animations developed through research at the "Flash Center" are available here. The collection offers .avi, .flv, or .mpeg file downloads as well as references to related research papers or presentations.

  8. Stellar dynamics. The fastest unbound star in our Galaxy ejected by a thermonuclear supernova.

    PubMed

    Geier, S; Fürst, F; Ziegerer, E; Kupfer, T; Heber, U; Irrgang, A; Wang, B; Liu, Z; Han, Z; Sesar, B; Levitan, D; Kotak, R; Magnier, E; Smith, K; Burgett, W S; Chambers, K; Flewelling, H; Kaiser, N; Wainscoat, R; Waters, C

    2015-03-01

    Hypervelocity stars (HVSs) travel with velocities so high that they exceed the escape velocity of the Galaxy. Several acceleration mechanisms have been discussed. Only one HVS (US 708, HVS 2) is a compact helium star. Here we present a spectroscopic and kinematic analysis of US 708. Traveling with a velocity of ~1200 kilometers per second, it is the fastest unbound star in our Galaxy. In reconstructing its trajectory, the Galactic center becomes very unlikely as an origin, which is hardly consistent with the most favored ejection mechanism for the other HVSs. Furthermore, we detected that US 708 is a fast rotator. According to our binary evolution model, it was spun-up by tidal interaction in a close binary and is likely to be the ejected donor remnant of a thermonuclear supernova.

  9. A low-level activation technique for monitoring thermonuclear fusion plasma conditions.

    PubMed

    Gasparro, Joël; Hult, Mikael; Bonheure, Georges; Johnston, Peter N

    2006-01-01

    Optimisation of the confinement and sustainability of a thermonuclear plasma requires methods to monitor processes in the plasma. In this work three materials were used as activation targets (Ti, MgF2 and a TiVAl compound). They were placed inside the joint European Torus (JET) vacuum chamber. Certain gamma-ray emitting radionuclides (7Be, 54Mn, 56Co, 57Co, 58Co and 46Sc) were measured using ultra low-level gamma-ray spectrometry in an underground laboratory 1-2 months after activation. They were found to arise from neutron activation of bulk sample material and surface contaminants sputtered from other Tokamak parts. Decision thresholds for some activation products were determined in order to aid in giving upper bounds for the flux of charged particles.

  10. Temperature measurement during thermonuclear X-ray bursts with BeppoSAX

    NASA Astrophysics Data System (ADS)

    Beri, Aru; Paul, Biswajit; Orlandini, Mauro; Maitra, Chandreyee

    2016-05-01

    We have carried out a study of temperature evolution during thermonuclear bursts in LMXBs using broad band data from two instruments onboard BeppoSAX, the MECSand the PDS. However, instead of applying the standard technique of time resolved spectroscopy, we have determined the temperature in small time intervals using the ratio of count rates in the two instruments assuming a blackbody nature of burst emission and different interstellar absorption for different sources. Data from a total of twelve observations of six sources were analyzed during which 22 bursts were detected. We have obtained temperatures as high as ˜3.0 keV, even when there is no evidence of photospheric radius expansion. These high temperatures were observed in the sources within different broadband spectral states (soft and hard).

  11. VizieR Online Data Catalog: Models of thermonuclear X-ray bursters (Lampe+, 2016)

    NASA Astrophysics Data System (ADS)

    Lampe, N.; Heger, A.; Galloway, D. K.

    2016-05-01

    Using the KEPLER 1D hydrodynamics code (Woosley et al. 2004ApJS..151...75W), 464 models of thermonuclear X-ray bursters were performed across a range of accretion rates and compositions. We present the library of simulated burst profiles from this sample, and examine variations in the simulated light curve for different model conditions. We find that the recurrence time varies as a power law against accretion rate, and measure its slope while mixed H/He burning is occurring for a range of metallicities, finding the power law gradient to vary from {eta}=1.1 to 1.24. We identify the accretion rates at which mixed H/He burning stops and a transition occurs to different burning regimes. We explore how varying the accretion rate and metallicity affects burst morphology in both the rise and tail. (1 data file).

  12. SPIRAL INSTABILITY CAN DRIVE THERMONUCLEAR EXPLOSIONS IN BINARY WHITE DWARF MERGERS

    SciTech Connect

    Kashyap, Rahul; Fisher, Robert; García-Berro, Enrique; Aznar-Siguán, Gabriela; Lorén-Aguilar, Pablo

    2015-02-10

    Thermonuclear, or Type Ia supernovae (SNe Ia), originate from the explosion of carbon–oxygen white dwarfs, and serve as standardizable cosmological candles. However, despite their importance, the nature of the progenitor systems that give rise to SNe Ia has not been hitherto elucidated. Observational evidence favors the double-degenerate channel in which merging white dwarf binaries lead to SNe Ia. Furthermore, significant discrepancies exist between observations and theory, and to date, there has been no self-consistent merger model that yields a SNe Ia. Here we show that a spiral mode instability in the accretion disk formed during a binary white dwarf merger leads to a detonation on a dynamical timescale. This mechanism sheds light on how white dwarf mergers may frequently yield SNe Ia.

  13. The Influence of Accretion Rate and Metallicity on Thermonuclear Bursts: Predictions from KEPLER Models

    NASA Astrophysics Data System (ADS)

    Lampe, Nathanael; Heger, Alexander; Galloway, Duncan K.

    2016-03-01

    Using the KEPLER hydrodynamics code, 464 models of thermonuclear X-ray bursters were performed across a range of accretion rates and compositions. We present the library of simulated burst profiles from this sample, and examine variations in the simulated light curve for different model conditions. We find that the recurrence time varies as a power law against accretion rate, and measure its slope while mixed H/He burning is occurring for a range of metallicities, finding the power law gradient to vary from η =1.1 to 1.24. We identify the accretion rates at which mixed H/He burning stops and a transition occurs to different burning regimes. We explore how varying the accretion rate and metallicity affects burst morphology in both the rise and tail.

  14. The effect of relativistic Compton scattering on thermonuclear burn of pure deuterium fuel

    NASA Astrophysics Data System (ADS)

    Ghasemizad, A.; Nazirzadeh, M.; Khanbabaei, B.

    2016-08-01

    The relativistic effects of the Compton scattering on the thermonuclear burn-up of pure deuterium fuel in non-equilibrium plasma have been studied by four temperature (4T) theory. In the limit of low electron temperatures and photon energies, the nonrelativistic Compton scattering is valid and a convenient approximation, but in the high energy exchange rates between electrons and photons, is seen to break down. The deficiencies of the nonrelativistic approximation can be overcome by using the relativistic correction in the photons kinetic equation. In this research, we have utilized the four temperature (4T) theory to calculate the critical burn-up parameter for pure deuterium fuel, while the Compton scattering is considered as a relativistic phenomenon. It was shown that the measured critical burn-up parameter in ignition with relativistic Compton scattering is smaller than that of the parameter in the ignition with the nonrelativistic Compton scattering.

  15. Dynamic Modeling and Control Studies of a Two-Stage Bubbling Fluidized Bed Adsorber-Reactor for Solid-Sorbent CO{sub 2} Capture

    SciTech Connect

    Modekurti, Srinivasarao; Bhattacharyya, Debangsu; Zitney, Stephen E.

    2013-07-31

    A one-dimensional, non-isothermal, pressure-driven dynamic model has been developed for a two-stage bubbling fluidized bed (BFB) adsorber-reactor for solid-sorbent carbon dioxide (CO{sub 2}) capture using Aspen Custom Modeler® (ACM). The BFB model for the flow of gas through a continuous phase of downward moving solids considers three regions: emulsion, bubble, and cloud-wake. Both the upper and lower reactor stages are of overflow-type configuration, i.e., the solids leave from the top of each stage. In addition, dynamic models have been developed for the downcomer that transfers solids between the stages and the exit hopper that removes solids from the bottom of the bed. The models of all auxiliary equipment such as valves and gas distributor have been integrated with the main model of the two-stage adsorber reactor. Using the developed dynamic model, the transient responses of various process variables such as CO{sub 2} capture rate and flue gas outlet temperatures have been studied by simulating typical disturbances such as change in the temperature, flowrate, and composition of the incoming flue gas from pulverized coal-fired power plants. In control studies, the performance of a proportional-integral-derivative (PID) controller, feedback-augmented feedforward controller, and linear model predictive controller (LMPC) are evaluated for maintaining the overall CO{sub 2} capture rate at a desired level in the face of typical disturbances.

  16. A burst from a thermonuclear runaway on an ONeMg white dwarf

    NASA Technical Reports Server (NTRS)

    Starrfield, S.; Politano, M.; Truran, J. W.; Sparks, W. M.

    1992-01-01

    Studies which examine the consequences of accretion, at rates of 10(exp -9) solar mass/yr and 10(exp -10) solar mass/yr, onto an ONeMg white dwarf with a mass of 1.35 solar masses are performed. In these studies, a Lagrangian, hydrodynamic, one-dimensional computer code was used. The code now includes a network with 89 nuclei up to Ca-40, elemental diffusion, new opacities, and new equation of state. The initial abundance distribution corresponded to a mixture that was enriched to either 25, 50, or 75 percent in products of carbon burning. The remaining material in each case is assumed to have a solar composition. The evolution of the thermonuclear runaway in the 1.35 solar mass white dwarf, with M = 10(exp -9) solar mass, produced peak temperatures in the shell source exceeding 300 million degrees. The sequence produced significant amounts of Na-22 from proton captures onto Ne-20 and significant amounts of Al-26 from proton captures on Mg-24. This sequence ejected 5.2 x 10(exp -6) solar mass moving with speeds from approximately 100 km/s to 2300 km/s. When the mass accretion rate was decreased to 10(exp -10) solar mass, the resulting thermonuclear runaway produced a shock that moved through the outer envelope of the white dwarf and raised the surface luminosity to L greater than 10(exp 7) solar luminosity and the effective temperature to values exceeding 10(exp 7) K. The interaction of the material expanding from off of the white dwarf with the accretion disk should produce a burst of gamma-rays.

  17. RELATIVISTIC COLLAPSE AND EXPLOSION OF ROTATING SUPERMASSIVE STARS WITH THERMONUCLEAR EFFECTS

    SciTech Connect

    Montero, Pedro J.; Janka, Hans-Thomas; Mueller, Ewald

    2012-04-10

    We present results of general relativistic simulations of collapsing supermassive stars with and without rotation using the two-dimensional general relativistic numerical code Nada, which solves the Einstein equations written in the BSSN formalism and the general relativistic hydrodynamic equations with high-resolution shock-capturing schemes. These numerical simulations use an equation of state that includes the effects of gas pressure and, in a tabulated form, those associated with radiation and the electron-positron pairs. We also take into account the effect of thermonuclear energy released by hydrogen and helium burning. We find that objects with a mass of Almost-Equal-To 5 Multiplication-Sign 10{sup 5} M{sub Sun} and an initial metallicity greater than Z{sub CNO} Almost-Equal-To 0.007 do explode if non-rotating, while the threshold metallicity for an explosion is reduced to Z{sub CNO} Almost-Equal-To 0.001 for objects uniformly rotating. The critical initial metallicity for a thermonuclear explosion increases for stars with a mass Almost-Equal-To 10{sup 6} M{sub Sun }. For those stars that do not explode, we follow the evolution beyond the phase of black hole (BH) formation. We compute the neutrino energy loss rates due to several processes that may be relevant during the gravitational collapse of these objects. The peak luminosities of neutrinos and antineutrinos of all flavors for models collapsing to a BH are L{sub {nu}} {approx} 10{sup 55} erg s{sup -1}. The total radiated energy in neutrinos varies between E{sub {nu}} {approx} 10{sup 56} erg for models collapsing to a BH and E{sub {nu}} {approx} 10{sup 45}-10{sup 46} erg for models exploding.

  18. Relativistic Collapse and Explosion of Rotating Supermassive Stars with Thermonuclear Effects

    NASA Astrophysics Data System (ADS)

    Montero, Pedro J.; Janka, Hans-Thomas; Müller, Ewald

    2012-04-01

    We present results of general relativistic simulations of collapsing supermassive stars with and without rotation using the two-dimensional general relativistic numerical code Nada, which solves the Einstein equations written in the BSSN formalism and the general relativistic hydrodynamic equations with high-resolution shock-capturing schemes. These numerical simulations use an equation of state that includes the effects of gas pressure and, in a tabulated form, those associated with radiation and the electron-positron pairs. We also take into account the effect of thermonuclear energy released by hydrogen and helium burning. We find that objects with a mass of ≈5 × 105 M ⊙ and an initial metallicity greater than Z CNO ≈ 0.007 do explode if non-rotating, while the threshold metallicity for an explosion is reduced to Z CNO ≈ 0.001 for objects uniformly rotating. The critical initial metallicity for a thermonuclear explosion increases for stars with a mass ≈106 M ⊙. For those stars that do not explode, we follow the evolution beyond the phase of black hole (BH) formation. We compute the neutrino energy loss rates due to several processes that may be relevant during the gravitational collapse of these objects. The peak luminosities of neutrinos and antineutrinos of all flavors for models collapsing to a BH are L ν ~ 1055 erg s-1. The total radiated energy in neutrinos varies between E ν ~ 1056 erg for models collapsing to a BH and E ν ~ 1045-1046 erg for models exploding.

  19. Investigation of plant control strategies for the supercritical C0{sub 2}Brayton cycle for a sodium-cooled fast reactor using the plant dynamics code.

    SciTech Connect

    Moisseytsev, A.; Sienicki, J.

    2011-04-12

    The development of a control strategy for the supercritical CO{sub 2} (S-CO{sub 2}) Brayton cycle has been extended to the investigation of alternate control strategies for a Sodium-Cooled Fast Reactor (SFR) nuclear power plant incorporating a S-CO{sub 2} Brayton cycle power converter. The SFR assumed is the 400 MWe (1000 MWt) ABR-1000 preconceptual design incorporating metallic fuel. Three alternative idealized schemes for controlling the reactor side of the plant in combination with the existing automatic control strategy for the S-CO{sub 2} Brayton cycle are explored using the ANL Plant Dynamics Code together with the SAS4A/SASSYS-1 Liquid Metal Reactor (LMR) Analysis Code System coupled together using the iterative coupling formulation previously developed and implemented into the Plant Dynamics Code. The first option assumes that the reactor side can be ideally controlled through movement of control rods and changing the speeds of both the primary and intermediate coolant system sodium pumps such that the intermediate sodium flow rate and inlet temperature to the sodium-to-CO{sub 2} heat exchanger (RHX) remain unvarying while the intermediate sodium outlet temperature changes as the load demand from the electric grid changes and the S-CO{sub 2} cycle conditions adjust according to the S-CO{sub 2} cycle control strategy. For this option, the reactor plant follows an assumed change in load demand from 100 to 0 % nominal at 5 % reduction per minute in a suitable fashion. The second option allows the reactor core power and primary and intermediate coolant system sodium pump flow rates to change autonomously in response to the strong reactivity feedbacks of the metallic fueled core and assumed constant pump torques representing unchanging output from the pump electric motors. The plant behavior to the assumed load demand reduction is surprising close to that calculated for the first option. The only negative result observed is a slight increase in the intermediate

  20. Nuclear reactor

    DOEpatents

    Pennell, William E.; Rowan, William J.

    1977-01-01

    A nuclear reactor in which the core components, including fuel-rod assemblies, control-rod assemblies, fertile rod-assemblies, and removable shielding assemblies, are supported by a plurality of separate inlet modular units. These units are referred to as inlet module units to distinguish them from the modules of the upper internals of the reactor. The modular units are supported, each removable independently of the others, in liners in the supporting structure for the lower internals of the reactor. The core assemblies are removably supported in integral receptacles or sockets of the modular units. The liners, units, sockets and assmblies have inlet openings for entry of the fluid. The modular units are each removably mounted in the liners with fluid seals interposed between the opening in the liner and inlet module into which the fluid enters and the upper and lower portion of the liner. Each assembly is similarly mounted in a corresponding receptacle with fluid seals interposed between the openings where the fluid enters and the lower portion of the receptacle or fitting closely in these regions. As fluid flows along each core assembly a pressure drop is produced along the fluid so that the fluid which emerges from each core assembly is at a lower pressure than the fluid which enters the core assembly. However because of the seals interposed in the mountings of the units and assemblies the pressures above and below the units and assemblies are balanced and the units are held in the liners and the assemblies are held in the receptacles by their weights as they have a higher specific gravity than the fluid. The low-pressure spaces between each module and its liner and between each core assembly and its module is vented to the low-pressure regions of the vessel to assure that fluid which leaks through the seals does not accumulate and destroy the hydraulic balance.

  1. NEUTRONIC REACTOR

    DOEpatents

    Daniels, F.

    1959-10-27

    A reactor in which at least a portion of the moderator is in the form of movable refractory balls is described. In addition to their moderating capacity, these balls may serve as carriers for fissionable material or fertile material, or may serve in a coolant capacity to remove heat from the reactor. A pneumatic system is used to circulate the balls through the reactor.

  2. Reactor neutrino monitoring

    NASA Astrophysics Data System (ADS)

    Lhuillier, D.

    2009-03-01

    Nuclear reactors are the most intense man-controlled sources of antineutrinos and as such have hosted number of key physics experiments, from the antineutrino discovery to modern oscillation measurements. At the present time, both detection technology and understanding of fundamental physics are mature enough to think about antineutrinos as a new tool for reactor monitoring. We describe below how antineutrinos can provide online information on reactor operation and amount of plutonium accumulated in the core. Reactors are the only sources of plutonium on earth and this element can be chemically separated from the rest of the nuclear fuel and diverted into nuclear weapons. We present in the next sections the unique features antineutrino detectors could provide to safeguards agencies such as IAEA. We review the worldwide efforts to develop small ( 1m scale) antineutrino detectors dedicated to automated and non-intrusive reactor monitoring.

  3. Research reactors

    SciTech Connect

    Tonneson, L.C.; Fox, G.J.

    1996-04-01

    There are currently 284 research reactors in operation, and 12 under construction around the world. Of the operating reactors, nearly two-thirds are used exclusively for research, and the rest for a variety of purposes, including training, testing, and critical assembly. For more than 50 years, research reactor programs have contributed greatly to the scientific and educational communities. Today, six of the world`s research reactors are being shut down, three of which are in the USA. With government budget constraints and the growing proliferation concerns surrounding the use of highly enriched uranium in some of these reactors, the future of nuclear research could be impacted.

  4. CONVECTION REACTOR

    DOEpatents

    Hammond, R.P.; King, L.D.P.

    1960-03-22

    An homogeneous nuclear power reactor utilizing convection circulation of the liquid fuel is proposed. The reactor has an internal heat exchanger looated in the same pressure vessel as the critical assembly, thereby eliminating necessity for handling the hot liquid fuel outside the reactor pressure vessel during normal operation. The liquid fuel used in this reactor eliminates the necessity for extensive radiolytic gas rocombination apparatus, and the reactor is resiliently pressurized and, without any movable mechanical apparatus, automatically regulates itself to the condition of criticality during moderate variations in temperature snd pressure and shuts itself down as the pressure exceeds a predetermined safe operating value.

  5. Purification and Chemical Control of Molten Li2BeF 4 for a Fluoride Salt Cooled Reactor

    NASA Astrophysics Data System (ADS)

    Kelleher, Brian Christopher

    Out of the many proposed generation IV, high-temperature reactors, the molten salt reactor (MSR) is one of the most promising. The first large scale MSR, the molten salt reactor experiment (MSRE), operated from 1965 to 1969 using Li2BeF4, or flibe, as a coolant and solvent for uranium fluoride fuel, at maximum temperatures of 654°C, for over 15000 hours. The MSRE experienced no concept breaking surprises and was considered a success. Newly proposed designs of molten salt reactors use solid fuels, making them less exotic compared to the MSRE. However, any molten salt reactor will require a great deal of research pertaining to the chemical and mechanical mastery of molten salts in order to prepare it for commercialization. To supplement the development of new molten salt reactors, approximately 100 kg of flibe was purified using the standard hydrofluorination process. Roughly half of the purified salt was lithium-7 enriched salt from the secondary loop of the MSRE. Purification rids the salt of impurities and reduces its capacity for corrosion, also known as the redox potential. The redox potential of flibe was measured at various stages of purification for the first time using a dynamic beryllium reference electrode. These redox measurements have been superimposed with metal impurities measurements found by neutron activation analysis. Lastly, reductions of flibe with beryllium metal have been investigated. Over reductions have been performed, which have shown to decrease redox potential while seemingly creating a beryllium-beryllium halide system. Recommendations of the lowest advisable redox potential for corrosion tests are included along with suggestions for future work.

  6. A Remarkable Three Hour Thermonuclear Burst from 4U 1820-30

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; Brown, Edward F.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present a detailed observational and theoretical study of an approximately three hour long X-ray burst (the "super burst") observed by the Rossi X-ray Timing Explorer (RXTE) from the low mass X-ray binary (LMXB) 4U 1820-30. This is the longest X-ray burst ever observed from this source, and perhaps one of the longest ever observed in great detail from any source. We show that the super burst is thermonuclear in origin. Its peak luminosity of approximately 3.4 x 10(exp 38) ergs s(exp -1) is consistent with the helium Eddington limit for a neutron star at approximately 7 kpc, as well as the peak luminosity of other, shorter, thermonuclear bursts from the same source. The super burst begins in the decaying tail of a more typical (approximately equal to 20 s duration) thermonuclear burst. These shorter, more frequent bursts are well known helium flashes from this source. The level of the accretion driven flux as well as the observed energy release of upwards of 1.5 x 10(exp 42) ergs indicate that helium could not be the energy source for the super burst. We outline the physics relevant to carbon production and burning on helium accreting neutron stars and present calculations of the thermal evolution and stability of a carbon layer and show that this process is the most likely explanation for the super burst. Ignition at the temperatures in the deep carbon "ocean" requires greater than 30 times the mass of carbon inferred from the observed burst energetics unless the He flash is able to trigger a deflagration from a much smaller mass of carbon. We show, however, that for large columns of accreted carbon fuel, a substantial fraction of the energy released in the carbon burning layer is radiated away as neutrinos, and the heat that is conducted from the burning layer in large part flows inward, only to be released on timescales longer than the observed burst. Thus the energy released during the event possibly exceeds that observed in X-rays by more than a factor of

  7. The effects of variations in nuclear interactions on nucleosynthesis in thermonuclear supernovae

    NASA Astrophysics Data System (ADS)

    Parikh, A.; José, J.; Seitenzahl, I. R.; Röpke, F. K.

    2013-09-01

    Context. Type Ia supernova explosions are violent stellar events important for their contribution to the cosmic abundance of iron peak elements and for their role as cosmological distance indicators. Aims: The impact of nuclear physics uncertainties on nucleosynthesis in thermonuclear supernovae has not been fully explored using comprehensive and systematic studies with multiple models. To better constrain predictions of yields from these phenomena, we investigate thermonuclear reaction rates and weak interaction rates that significantly affect yields in our underlying models. Methods: We have performed a sensitivity study by postprocessing thermodynamic histories from two different hydrodynamic, Chandrasekhar-mass explosion models. We have individually varied all input reaction and, for the first time, weak interaction rates by a factor of ten (up and down) and compared the yields in each case to yields using standard rates. Results: Of the 2305 nuclear reactions in our network, we find that in either model the rates of only 53 reactions affect the yield of any species with an abundance of at least 10-8 M⊙ by at least a factor of two. The rates of the 12C(α,γ), 12C+12C, 20Ne(α,p), 20Ne(α,γ), and 30Si(p,γ) reactions are among those that modify the most yields when varied by a factor of ten. From the individual variation of 658 weak interaction rates in our network by a factor of ten, only the stellar 28Si(β+)28Al, 32S(β+)32P, and 36Ar(β+)36Cl rates significantly affect the yields of species in a model. Additional tests reveal that reaction rate changes over temperatures T > 1.5 GK have the greatest impact and that ratios of radionuclides that may be used as explosion diagnostics change by a factor of ≲2 from the variation of individual rates by a factor of ten. Conclusions: Nucleosynthesis in the two adopted models is relatively robust to variations in individual nuclear reaction and weak interaction rates. Laboratory measurements of a limited number

  8. Igniting the Light Elements: The Los Alamos Thermonuclear Weapon Project, 1942-1952

    SciTech Connect

    Anne C. Fitzpatrick

    1999-07-01

    The American system of nuclear weapons research and development was conceived and developed not as a result of technological determinism, but by a number of individual architects who promoted the growth of this large technologically-based complex. While some of the technological artifacts of this system, such as the fission weapons used in World War II, have been the subject of many historical studies, their technical successors--fusion (or hydrogen) devices--are representative of the largely unstudied highly secret realms of nuclear weapons science and engineering. In the postwar period a small number of Los Alamos Scientific Laboratory's staff and affiliates were responsible for theoretical work on fusion weapons, yet the program was subject to both the provisions and constraints of the US Atomic Energy Commission, of which Los Alamos was a part. The Commission leadership's struggle to establish a mission for its network of laboratories, least of all to keep them operating, affected Los Alamos's leaders' decisions as to the course of weapons design and development projects. Adapting Thomas P. Hughes's ''large technological systems'' thesis, I focus on the technical, social, political, and human problems that nuclear weapons scientists faced while pursuing the thermonuclear project, demonstrating why the early American thermonuclear bomb project was an immensely complicated scientific and technological undertaking. I concentrate mainly on Los Alamos Scientific Laboratory's Theoretical, or T, Division, and its members' attempts to complete an accurate mathematical treatment of the ''Super''--the most difficult problem in physics in the postwar period--and other fusion weapon theories. Although tackling a theoretical problem, theoreticians had to address technical and engineering issues as well. I demonstrate the relative value and importance of H-bomb research over time in the postwar era to scientific, politician, and military participants in this project. I

  9. Compact power reactor

    DOEpatents

    Wetch, Joseph R.; Dieckamp, Herman M.; Wilson, Lewis A.

    1978-01-01

    There is disclosed a small compact nuclear reactor operating in the epithermal neutron energy range for supplying power at remote locations, as for a satellite. The core contains fuel moderator elements of Zr hydride with 7 w/o of 93% enriched uranium alloy. The core has a radial beryllium reflector and is cooled by liquid metal coolant such as NaK. The reactor is controlled and shut down by moving portions of the reflector.

  10. Job/task analysis for I C (Instrumentation and Controls) instrument technicians at the High Flux Isotope Reactor

    SciTech Connect

    Duke, L.L.

    1989-09-01

    To comply with Department of Energy Order 5480.XX (Draft), a job/task analysis was initiated by the Maintenance Management Department at Oak Ridge National Laboratory (ORNL). The analysis was applicable to instrument technicians working at the ORNL High Flux Isotope Reactor (HFIR). This document presents the procedures and results of that analysis. 2 refs., 2 figs.

  11. Influence of the tritium beta(-) decay on low-temperature thermonuclear burn-up in deuterium-tritium mixtures

    PubMed

    Frolov

    2000-09-01

    Low-temperature (Tthermonuclear burn-up in deuterium-tritium mixtures with various deuterium-tritium-helium-3 ratios is considered. The general dependence is studied for the critical burn-up parameter x(c)=rhor(c) upon the initial temperature T, density rho(0), and tritium molar concentration y for the [D]:y[T]:(1-y)[3He] mixture. In particular, it is shown that, if the tritium concentration y decreases, then the critical burn-up parameter x(c)(T,rho(0),y) grows very quickly (at fixed T and rho(0)). This means that tritium beta(-) decay significantly complicates thermonuclear burn-up in deuterium-tritium mixtures.

  12. Nuclear reactor

    DOEpatents

    Yant, Howard W.; Stinebiser, Karl W.; Anzur, Gregory C.

    1977-01-01

    A nuclear reactor, particularly a liquid-metal breeder reactor, whose upper internals include outlet modules for channeling the liquid-metal coolant from selected areas of the outlet of the core vertically to the outlet plenum. The modules are composed of a highly-refractory, high corrosion-resistant alloy, for example, INCONEL-718. Each module is disposed to confine and channel generally vertically the coolant emitted from a subplurality of core-component assemblies. Each module has a grid with openings, each opening disposed to receive the coolant from an assembly of the subplurality. The grid in addition serves as a holdown for the assemblies of the corresponding subplurality preventing their excessive ejection upwardly from the core. In the region directly over the core the outlet modules are of such peripheral form that they nest forming a continuum over the core-component assemblies whose outlet coolant they confine. Each subassembly includes a chimney which confines the coolant emitted by its corresponding subassemblies to generally vertical flow between the outlet of the core and the outlet plenum. Each subplurality of assemblies whose emitted coolant is confined by an outlet module includes assemblies which emit lower-temperature coolant, for example, a control-rod assembly, or fertile assemblies, and assemblies which emit coolant of substantially higher temperature, for example, fuel-rod assemblies. The coolants of different temperatures are mixed in the chimneys reducing the effect of stripping (hot-cold temperature fluctuations) on the remainder of the upper internals which are composed typically of AISI-304 or AISI-316 stainless steel.

  13. NEUTRONIC REACTOR

    DOEpatents

    Fraas, A.P.; Mills, C.B.

    1961-11-21

    A neutronic reactor in which neutron moderation is achieved primarily in its reflector is described. The reactor structure consists of a cylindrical central "island" of moderator and a spherical moderating reflector spaced therefrom, thereby providing an annular space. An essentially unmoderated liquid fuel is continuously passed through the annular space and undergoes fission while contained therein. The reactor, because of its small size, is particularly adapted for propulsion uses, including the propulsion of aircraft. (AEC)

  14. Medical effects of exposure of human beings to fallout radiation from a thermonuclear explosion.

    PubMed

    Cronkite, E P; Bond, V P; Conard, R A

    1995-05-01

    On March 1, 1954, after detonation of a thermonuclear device on Bikini atoll, an unexpected wind shift resulted in the deposition of radioactive fallout on inhabited atolls. The fallout radiation caused fleeting systemic effects, dose-dependent depression of hematopoiesis and skin burns primarily due to the beta ray component of the fission radionuclides. Within a few weeks, hematopoietic recovery was substantial but slight depression of blood counts was maintained for several years. One case of fatal acute myeloblastic leukemia developed in a boy receiving 1.9 Gy as an infant. Cretinism developed in two boys exposed as infants with estimated thyroidal dose in excess of 50 Gy. Chemical hypothyroidism was detected in several persons. Thyroid adenomas and cancer commenced appearance ten years after exposure and became a major long-term medical problem. There have been no late effects attributable to the beta burns 40 years after exposure. Internal contamination from ingestion and inhalation of radionuclides is detectable. The doses are comparable to background levels in the U.S. There is no detectible decrease in longevity of the exposed Marshallese compared to an unexposed Marshallese population.

  15. Collision Models for Plasma Simulation of Thermonuclear Burn: Comparison of Models and Applications

    NASA Astrophysics Data System (ADS)

    Winske, Dan; Albright, Brian; Bowers, Kevin; Lemons, Don

    2007-11-01

    There is renewed interest in examining plasma physics issues related to thermonuclear burn in inertial confinement fusion (ICF) and fast ignition (FI): e.g., the rate of temperature equilibration of electrons and ions, the formation and/or depletion of high energy tails of ion velocity distributions of ions, the slowing of energetic ions in dense plasmas, etc. To address these types of questions, we have developed a new particle-in-cell (PIC) plasma simulation capability, embodied in the code VPIC. To model TN-burn problems in dense plasmas, we have developed a new Coulomb collision model, based on the use of stochastic differential equations and well-known Spitzer rates to describe the collision process, which was presented at last year's meeting. Here we extend the model to included arbitrary weighting of individual simulation particles, rather than just separate weights for each plasma species, which is a feature intrinsic to VPIC. We compare test cases for plasma relaxation and slowing of fast beams using the new collision model with results obtained from an extension of standard particle-pairing collision models to weighted particles for parameter regimes of interest to ICF and FI.

  16. IGNITION COLUMN DEPTHS OF HELIUM-RICH THERMONUCLEAR BURSTS FROM 4U 1728-34

    SciTech Connect

    Misanovic, Zdenka; Galloway, Duncan K.; Cooper, Randall L.

    2010-08-01

    We analyzed thermonuclear (type I) X-ray bursts observed from the low-mass X-ray binary 4U 1728-34 by RXTE, Chandra, and INTEGRAL. We compared the variation in burst energy and recurrence times as a function of accretion rate with the predictions of a numerical ignition model including a treatment of the heating and cooling in the crust. We found that the measured burst ignition column depths are significantly below the theoretically predicted values, regardless of the assumed thermal structure of the neutron star (NS) interior. While it is possible that the accretion rate measured by Chandra is underestimated, due to additional persistent spectral components outside the sensitivity band, the required correction factor is typically 3.6 and as high as 6, which is implausible. Furthermore, such underestimation is even more unlikely for RXTE and INTEGRAL, which have much broader bandpasses. Possible explanations for the observed discrepancy include shear-triggered mixing of the accreted helium to larger column depths, resulting in earlier ignition, or the fractional covering of the accreted fuel on the NS surface.

  17. Thermonuclear ignition in inertial confinement fusion and comparison with magnetic confinementa)

    NASA Astrophysics Data System (ADS)

    Betti, R.; Chang, P. Y.; Spears, B. K.; Anderson, K. S.; Edwards, J.; Fatenejad, M.; Lindl, J. D.; McCrory, R. L.; Nora, R.; Shvarts, D.

    2010-05-01

    The physics of thermonuclear ignition in inertial confinement fusion (ICF) is presented in the familiar frame of a Lawson-type criterion. The product of the plasma pressure and confinement time Pτ for ICF is cast in terms of measurable parameters and its value is estimated for cryogenic implosions. An overall ignition parameter χ including pressure, confinement time, and temperature is derived to complement the product Pτ. A metric for performance assessment should include both χ and Pτ. The ignition parameter and the product Pτ are compared between inertial and magnetic-confinement fusion. It is found that cryogenic implosions on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have achieved Pτ ˜1.5 atm s comparable to large tokamaks such as the Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] where Pτ ˜1 atm s. Since OMEGA implosions are relatively cold (T ˜2 keV), their overall ignition parameter χ ˜0.02-0.03 is ˜5× lower than in JET (χ ˜0.13), where the average temperature is about 10 keV.

  18. Thermonuclear ignition in inertial confinement fusion and comparison with magnetic confinement

    SciTech Connect

    Betti, R.; Chang, P. Y.; Anderson, K. S.; Nora, R.; Spears, B. K.; Edwards, J.; Lindl, J. D.; Fatenejad, M.; McCrory, R. L.; Shvarts, D.

    2010-05-15

    The physics of thermonuclear ignition in inertial confinement fusion (ICF) is presented in the familiar frame of a Lawson-type criterion. The product of the plasma pressure and confinement time Ptau for ICF is cast in terms of measurable parameters and its value is estimated for cryogenic implosions. An overall ignition parameter chi including pressure, confinement time, and temperature is derived to complement the product Ptau. A metric for performance assessment should include both chi and Ptau. The ignition parameter and the product Ptau are compared between inertial and magnetic-confinement fusion. It is found that cryogenic implosions on OMEGA[T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have achieved Ptauapprox1.5 atm s comparable to large tokamaks such as the Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] where Ptauapprox1 atm s. Since OMEGA implosions are relatively cold (Tapprox2 keV), their overall ignition parameter chiapprox0.02-0.03 is approx5x lower than in JET (chiapprox0.13), where the average temperature is about 10 keV.

  19. Thermonuclear runaways in nova outbursts. 2: Effect of strong, instantaneous, local fluctuations

    NASA Technical Reports Server (NTRS)

    Shankar, Anurag; Arnett, David

    1994-01-01

    In an attempt to understand the manner in which nova outbursts are initiated on the surface of a white dwarf, we investigate the effects fluctuations have on the evolution of a thermonuclear runaway. Fluctuations in temperature density, or the composition of material in the burning shell may arise due to the chaotic flow field generated by convection when it occurs, or by the accretion process itself. With the aid of two-dimensional reactive flow calculations, we consider cases where a strong fluctutation in temperature arises during the early, quiescent accretion phase or during the later, more dynamic, explosion phase. In all cases we find that an instantaneous, local temperature fluctuation causes the affected material to become Rayleigh-Taylor unstable. The rapid rise and subsequent expansion of matter immediately cools the hot blob, which prevents the lateral propagation of burning. This suggests that local temperature fluctuations do not play a significant role in directly initiating the runaway, especially during the early stages. However, they may provide an efficient mechanism of mixing core material into the envelope (thereby pre-enriching the fuel for subsequent episodes of explosive hydrogen burning) and of mixing substantial amounts of the radioactive nucleus N-13 into the surface layers, making novae potential gamma-ray sources. This suggests that it is the global not the local, evolution of the core-envelope interface to high temperatures which dominates the development of the runaway. We also present a possible new scenario for the initiation of nova outbursts based on our results.

  20. Rotational effects in thermonuclear type I bursts: equatorial crossing and directionality of flame spreading

    NASA Astrophysics Data System (ADS)

    Cavecchi, Yuri; Watts, Anna L.; Levin, Yuri; Braithwaite, Jonathan

    2015-03-01

    In a previous study on thermonuclear (type I) bursts on accreting neutron stars, we addressed and demonstrated the importance of the effects of rotation, through the Coriolis force, on the propagation of the burning flame. However, that study only analysed cases of longitudinal propagation, where the Coriolis force coefficient 2Ωcos θ was constant. In this paper, we study the effects of rotation on propagation in the meridional (latitudinal) direction, where the Coriolis force changes from its maximum at the poles to zero at the equator. We find that the zero Coriolis force at the equator, while affecting the structure of the flame, does not prevent its propagation from one hemisphere to another. We also observe structural differences between the flame propagating towards the equator and that propagating towards the pole, the second being faster. In the light of the recent discovery of the low spin frequency of burster IGR J17480-2446 rotating at 11 Hz (for which Coriolis effects should be negligible), we also extend our simulations to slow rotation.

  1. Transmission of Thermonuclear Detonations through Layers of Burned Material in Carbon-Oxygen White Dwarfs

    NASA Astrophysics Data System (ADS)

    Gamezo, V. N.; Oran, E. S.

    2006-06-01

    In three-dimensional delayed-detonation models of type Ia supernovae, detonations propagate through funnels of degenerate carbon-oxygen matter that are left unburned by turbulent deflagrations in central parts of a white dwarf. Some of these funnels can be disconnected from the rest of the unburned material, thus creating unburned pockets that cannot be directly reached by a detonation wave. These pockets may or may not ignite when strong shocks generated by detonations reach them through layers of burned material. In this work, we study the detonation transmission phenomena in exploding white dwarfs using one-dimensional time-dependent numerical simulations based on reactive Euler equations. The thermonuclear burning of carbon-oxygen mixture is modeled by a 13-nuclei alpha network. We use a steady-state solution for the reaction-zone structure of a one-dimensional detonation wave as an initial condition. Time-dependent computations performed for a fully resolved carbon reaction scale show that a detonation shock passing through a layer of burned material can initiate a new detonation or decay. The critical thickness of burned material that allows the detonation reignition is a function of density. This work was supported in part by the NASA ATP program (NRA-02-OSS-01-ATP) and by the Naval Research Laboratory (NRL) through the Office of Naval Research.

  2. Thermonuclear targets for direct-drive ignition by a megajoule laser pulse

    SciTech Connect

    Bel’kov, S. A.; Bondarenko, S. V.; Vergunova, G. A.; Garanin, S. G.; Gus’kov, S. Yu. Demchenko, N. N.; Doskoch, I. Ya.; Kuchugov, P. A.; Zmitrenko, N. V.; Rozanov, V. B.; Stepanov, R. V.; Yakhin, R. A.

    2015-10-15

    Central ignition of a thin two-layer-shell fusion target that is directly driven by a 2-MJ profiled pulse of Nd laser second-harmonic radiation has been studied. The parameters of the target were selected so as to provide effective acceleration of the shell toward the center, which was sufficient for the onset of ignition under conditions of increased hydrodynamic stability of the ablator acceleration and compression. The aspect ratio of the inner deuterium-tritium layer of the shell does not exceed 15, provided that a major part (above 75%) of the outer layer (plastic ablator) is evaporated by the instant of maximum compression. The investigation is based on two series of numerical calculations that were performed using one-dimensional (1D) hydrodynamic codes. The first 1D code was used to calculate the absorption of the profiled laser-radiation pulse (including calculation of the total absorption coefficient with allowance for the inverse bremsstrahlung and resonance mechanisms) and the spatial distribution of target heating for a real geometry of irradiation using 192 laser beams in a scheme of focusing with a cubo-octahedral symmetry. The second 1D code was used for simulating the total cycle of target evolution under the action of absorbed laser radiation and for determining the thermonuclear gain that was achieved with a given target.

  3. Dynamic control of nutrient-removal from industrial wastewater in a sequencing batch reactor, using common and low-cost online sensors.

    PubMed

    Dries, Jan

    2016-01-01

    On-line control of the biological treatment process is an innovative tool to cope with variable concentrations of chemical oxygen demand and nutrients in industrial wastewater. In the present study we implemented a simple dynamic control strategy for nutrient-removal in a sequencing batch reactor (SBR) treating variable tank truck cleaning wastewater. The control system was based on derived signals from two low-cost and robust sensors that are very common in activated sludge plants, i.e. oxidation reduction potential (ORP) and dissolved oxygen. The amount of wastewater fed during anoxic filling phases, and the number of filling phases in the SBR cycle, were determined by the appearance of the 'nitrate knee' in the profile of the ORP. The phase length of the subsequent aerobic phases was controlled by the oxygen uptake rate measured online in the reactor. As a result, the sludge loading rate (F/M ratio), the volume exchange rate and the SBR cycle length adapted dynamically to the activity of the activated sludge and the actual characteristics of the wastewater, without affecting the final effluent quality. PMID:26901715

  4. Dynamic control of nutrient-removal from industrial wastewater in a sequencing batch reactor, using common and low-cost online sensors.

    PubMed

    Dries, Jan

    2016-01-01

    On-line control of the biological treatment process is an innovative tool to cope with variable concentrations of chemical oxygen demand and nutrients in industrial wastewater. In the present study we implemented a simple dynamic control strategy for nutrient-removal in a sequencing batch reactor (SBR) treating variable tank truck cleaning wastewater. The control system was based on derived signals from two low-cost and robust sensors that are very common in activated sludge plants, i.e. oxidation reduction potential (ORP) and dissolved oxygen. The amount of wastewater fed during anoxic filling phases, and the number of filling phases in the SBR cycle, were determined by the appearance of the 'nitrate knee' in the profile of the ORP. The phase length of the subsequent aerobic phases was controlled by the oxygen uptake rate measured online in the reactor. As a result, the sludge loading rate (F/M ratio), the volume exchange rate and the SBR cycle length adapted dynamically to the activity of the activated sludge and the actual characteristics of the wastewater, without affecting the final effluent quality.

  5. REACTOR COOLING

    DOEpatents

    Quackenbush, C.F.

    1959-09-29

    A nuclear reactor with provisions for selectively cooling the fuel elements is described. The reactor has a plurality of tubes extending throughout. Cylindrical fuel elements are disposed within the tubes and the coolant flows through the tubes and around the fuel elements. The fuel elements within the central portion of the reactor are provided with roughened surfaces of material. The fuel elements in the end portions of the tubes within the reactor are provlded with low conduction jackets and the fuel elements in the region between the central portion and the end portions are provided with smooth surfaces of high heat conduction material.

  6. NUCLEAR REACTOR FUEL ELEMENT

    DOEpatents

    Currier, E.L. Jr.; Nicklas, J.H.

    1963-06-11

    A fuel plate is designed for incorporation into control rods of the type utilized in high-flux test reactors. The fuel plate is designed so that the portion nearest the poison section of the control rod contains about one-half as much fissionable material as in the rest of the plate, thereby eliminating dangerous flux peaking in that portion. (AEC)

  7. Concepts and Tests for the Remote-Controlled Dismantling of the Biological Shield and Form work of the KNK Reactor - 13425

    SciTech Connect

    Neff, Sylvia; Graf, Anja; Petrick, Holger; Rothschmitt, Stefan; Klute, Stefan

    2013-07-01

    The compact sodium-cooled nuclear reactor facility Karlsruhe (KNK), a prototype Fast Breeder, is currently in an advanced stage of dismantling. Complete dismantling is based on 10 partial licensing steps. In the frame of the 9. decommissioning permit, which is currently ongoing, the dismantling of the biological shield is foreseen. The biological shield consists of heavy reinforced concrete with built-in steel fitments, such as form-work of the reactor tank, pipe sleeves, ventilation channels, and measuring devices. Due to the activation of the inner part of the biological shield, dismantling has to be done remote-controlled. During a comprehensive basic design phase a practical dismantling strategy was developed. Necessary equipment and tools were defined. Preliminary tests revealed that hot wire plasma cutting is the most favorable cutting technology due to the geometrical boundary conditions, the varying distance between cutter and material, and the heavy concrete behind the steel form-work. The cutting devices will be operated remotely via a carrier system with an industrial manipulator. The carrier system has expandable claws to adjust to the varying diameter of the reactor shaft during dismantling progress. For design approval of this prototype development, interaction between manipulator and hot wire plasma cutting was tested in a real configuration. For the demolition of the concrete structure, an excavator with appropriate tools, such as a hydraulic hammer, was selected. Other mechanical cutting devices, such as a grinder or rope saw, were eliminated because of concrete containing steel spheres added to increase the shielding factor of the heavy concrete. Dismantling of the biological shield will be done in a ring-wise manner due to static reasons. During the demolition process, the excavator is positioned on its tripod in three concrete recesses made prior to the dismantling of the separate concrete rings. The excavator and the manipulator carrier system

  8. A Simulink Library of cryogenic components to automatically generate control schemes for large Cryorefrigerators

    NASA Astrophysics Data System (ADS)

    Bonne, François; Alamir, Mazen; Hoa, Christine; Bonnay, Patrick; Bon-Mardion, Michel; Monteiro, Lionel

    2015-12-01

    In this article, we present a new Simulink library of cryogenics components (such as valve, phase separator, mixer, heat exchanger...) to assemble to generate model-based control schemes. Every component is described by its algebraic or differential equation and can be assembled with others to build the dynamical model of a complete refrigerator or the model of a subpart of it. The obtained model can be used to automatically design advanced model based control scheme. It also can be used to design a model based PI controller. Advanced control schemes aim to replace classical user experience designed approaches usually based on many independent PI controllers. This is particularly useful in the case where cryoplants are submitted to large pulsed thermal loads, expected to take place in future fusion reactors such as those expected in the cryogenic cooling systems of the International Thermonuclear Experimental Reactor (ITER) or the Japan Torus-60 Super Advanced Fusion Experiment (JT- 60SA). The paper gives the example of the generation of the dynamical model of the 400W@1.8K refrigerator and shows how to build a Constrained Model Predictive Control for it. Based on the scheme, experimental results will be given. This work is being supported by the French national research agency (ANR) through the ANR-13-SEED-0005 CRYOGREEN program.

  9. Physical control oriented model of large scale refrigerators to synthesize advanced control schemes. Design, validation, and first control results

    SciTech Connect

    Bonne, François; Bonnay, Patrick

    2014-01-29

    In this paper, a physical method to obtain control-oriented dynamical models of large scale cryogenic refrigerators is proposed, in order to synthesize model-based advanced control schemes. These schemes aim to replace classical user experience designed approaches usually based on many independent PI controllers. This is particularly useful in the case where cryoplants are submitted to large pulsed thermal loads, expected to take place in the cryogenic cooling systems of future fusion reactors such as the International Thermonuclear Experimental Reactor (ITER) or the Japan Torus-60 Super Advanced Fusion Experiment (JT-60SA). Advanced control schemes lead to a better perturbation immunity and rejection, to offer a safer utilization of cryoplants. The paper gives details on how basic components used in the field of large scale helium refrigeration (especially those present on the 400W @1.8K helium test facility at CEA-Grenoble) are modeled and assembled to obtain the complete dynamic description of controllable subsystems of the refrigerator (controllable subsystems are namely the Joule-Thompson Cycle, the Brayton Cycle, the Liquid Nitrogen Precooling Unit and the Warm Compression Station). The complete 400W @1.8K (in the 400W @4.4K configuration) helium test facility model is then validated against experimental data and the optimal control of both the Joule-Thompson valve and the turbine valve is proposed, to stabilize the plant under highly variable thermals loads. This work is partially supported through the European Fusion Development Agreement (EFDA) Goal Oriented Training Program, task agreement WP10-GOT-GIRO.

  10. Physical control oriented model of large scale refrigerators to synthesize advanced control schemes. Design, validation, and first control results

    NASA Astrophysics Data System (ADS)

    Bonne, François; Alamir, Mazen; Bonnay, Patrick

    2014-01-01

    In this paper, a physical method to obtain control-oriented dynamical models of large scale cryogenic refrigerators is proposed, in order to synthesize model-based advanced control schemes. These schemes aim to replace classical user experience designed approaches usually based on many independent PI controllers. This is particularly useful in the case where cryoplants are submitted to large pulsed thermal loads, expected to take place in the cryogenic cooling systems of future fusion reactors such as the International Thermonuclear Experimental Reactor (ITER) or the Japan Torus-60 Super Advanced Fusion Experiment (JT-60SA). Advanced control schemes lead to a better perturbation immunity and rejection, to offer a safer utilization of cryoplants. The paper gives details on how basic components used in the field of large scale helium refrigeration (especially those present on the 400W @1.8K helium test facility at CEA-Grenoble) are modeled and assembled to obtain the complete dynamic description of controllable subsystems of the refrigerator (controllable subsystems are namely the Joule-Thompson Cycle, the Brayton Cycle, the Liquid Nitrogen Precooling Unit and the Warm Compression Station). The complete 400W @1.8K (in the 400W @4.4K configuration) helium test facility model is then validated against experimental data and the optimal control of both the Joule-Thompson valve and the turbine valve is proposed, to stabilize the plant under highly variable thermals loads. This work is partially supported through the European Fusion Development Agreement (EFDA) Goal Oriented Training Program, task agreement WP10-GOT-GIRO.

  11. Application of a Virtual Reactivity Feedback Control Loop in Non-Nuclear Testing of a Fast Spectrum Reactor

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, Shannon M.; Forsbacka, Matthew

    2004-01-01

    For a compact, fast-spectrum reactor, reactivity feedback is dominated by core deformation at elevated temperature. Given the use of accurate deformation measurement techniques, it is possible to simulate nuclear feedback in non-nuclear electrically heated reactor tests. Implementation of simulated reactivity feedback in response to measured deflection is being tested at the NASA Marshall Space Flight Center Early Flight Fission Test Facility (EFF-TF). During tests of the SAFE-100 reactor prototype, core deflection was monitored using a high resolution camera. "virtual" reactivity feedback was accomplished by applying the results of Monte Carlo calculations (MCNPX) to core deflection measurements; the computational analysis was used to establish the reactivity worth of van'ous core deformations. The power delivered to the SAFE-100 prototype was then dusted accordingly via kinetics calculations, The work presented in this paper will demonstrate virtual reactivity feedback as core power was increased from 1 kilowatt(sub t), to 10 kilowatts(sub t), held approximately constant at 10 kilowatts (sub t), and then allowed to decrease based on the negative thermal reactivity coefficient.

  12. U.S. Department Of Energy Advanced Small Modular Reactor R&D Program: Instrumentation, Controls, and Human-Machine Interface (ICHMI) Pathway

    SciTech Connect

    Holcomb, David Eugene; Wood, Richard Thomas

    2013-01-01

    Instrumentation, controls, and human-machine interfaces (ICHMI) are essential enabling technologies that strongly influence nuclear power plant performance and operational costs. The nuclear power industry is currently engaged in a transition from traditional analog-based instrumentation, controls, and human-machine interface systems to implementations employing digital technologies. This transition has primarily occurred in an ad hoc fashion through individual system upgrades at existing plants and has been constrained by licenseability concerns. Although the recent progress in constructing new plants has spurred design of more fully digital plant-wide ICHMI systems, the experience base in the nuclear power application domain is limited. Additionally, development of advanced reactor concepts, such as Generation IV designs and small modular reactors, introduces different plant conditions (e.g., higher temperatures, different coolants, etc.) and unique plant configurations (e.g., multiunit plants with shared systems, balance of plant architectures with reconfigurable co-generation options) that increase the need for enhanced ICHMI capabilities to fully achieve industry goals related to economic competitiveness, safety and reliability, sustainability, and proliferation resistance and physical protection. As a result, significant challenges remain to be addressed to enable the nuclear power industry to complete the transition to safe and comprehensive use of modern ICHMI technology. The U.S. Department of Energy (DOE) has recognized that ICHMI research, development, and demonstration (RD&D) is needed to resolve the technical challenges that may compromise the effective and efficient utilization of modern ICHMI technology and consequently inhibit realization of the benefits offered by expanded utilization of nuclear power. Consequently, several DOE programs have substantial ICHMI RD&D elements within their respective research portfolios. This paper describes current

  13. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1958-04-22

    A nuclear reactor for isotope production is described. This reactor is designed to provide a maximum thermal neutron flux in a region adjacent to the periphery of the reactor rather than in the center of the reactor. The core of the reactor is generally centrally located with respect tn a surrounding first reflector, constructed of beryllium. The beryllium reflector is surrounded by a second reflector, constructed of graphite, which, in tune, is surrounded by a conventional thermal shield. Water is circulated through the core and the reflector and functions both as a moderator and a coolant. In order to produce a greatsr maximum thermal neutron flux adjacent to the periphery of the reactor rather than in the core, the reactor is designed so tbat the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the materials in the reflector is approximately twice the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the material of the core of the reactor.

  14. NEUTRONIC REACTOR

    DOEpatents

    Metcalf, H.E.; Johnson, H.W.

    1961-04-01

    BS>A nuclear reactor incorporating fuel rods passing through a moderator and including tubes of a material of higher Thermal conductivity than the fuel in contact with the fuel is described. The tubes extend beyond the active portion of the reactor into contant with a fiuld coolant.

  15. Reactor building

    SciTech Connect

    Hista, J. C.

    1984-09-18

    Reactor building comprising a vessel shaft anchored in a slab which is peripherally locked. This reactor building comprises a confinement enclosure within which are positioned internal structures constituted by an internal structure floor, a vessel shaft, a slab being positioned between the general floor and the internal structure floor, the vesse

  16. Nuclear reactor safety device

    DOEpatents

    Hutter, Ernest

    1986-01-01

    A safety device is disclosed for use in a nuclear reactor for axially repositioning a control rod with respect to the reactor core in the event of an upward thermal excursion. Such safety device comprises a laminated helical ribbon configured as a tube-like helical coil having contiguous helical turns with slidably abutting edges. The helical coil is disclosed as a portion of a drive member connected axially to the control rod. The laminated ribbon is formed of outer and inner laminae. The material of the outer lamina has a greater thermal coefficient of expansion than the material of the inner lamina. In the event of an upward thermal excursion, the laminated helical coil curls inwardly to a smaller diameter. Such inward curling causes the total length of the helical coil to increase by a substantial increment, so that the control rod is axially repositioned by a corresponding amount to reduce the power output of the reactor.

  17. Gas-cooled fast breeder reactor. Quarterly progress report, February 1-April 30, 1980

    SciTech Connect

    Not Available

    1980-05-01

    Information is presented concerning the reactor vessel; reactivity control mechanisms and instrumentation; reactor internals; primary coolant circuits;core auxiliary cooling system; reactor core; systems engineering; and reactor safety and reliability;

  18. Sensitivity study of explosive nucleosynthesis in type Ia supernovae: Modification of individual thermonuclear reaction rates

    NASA Astrophysics Data System (ADS)

    Bravo, Eduardo; Martínez-Pinedo, Gabriel

    2012-05-01

    Background: Type Ia supernovae contribute significantly to the nucleosynthesis of many Fe-group and intermediate-mass elements. However, the robustness of nucleosynthesis obtained via models of this class of explosions has not been studied in depth until now.Purpose: We explore the sensitivity of the nucleosynthesis resulting from thermonuclear explosions of massive white dwarfs with respect to uncertainties in nuclear reaction rates. We put particular emphasis on indentifying the individual reactions rates that most strongly affect the isotopic products of these supernovae.Method: We have adopted a standard one-dimensional delayed detonation model of the explosion of a Chandrasekhar-mass white dwarf and have postprocessed the thermodynamic trajectories of every mass shell with a nucleosynthetic code to obtain the chemical composition of the ejected matter. We have considered increases (decreases) by a factor of 10 on the rates of 1196 nuclear reactions (simultaneously with their inverse reactions), repeating the nucleosynthesis calculations after modification of each reaction rate pair. We have computed as well hydrodynamic models for different rates of the fusion reactions of 12C and of 16O. From the calculations we have selected the reactions that have the largest impact on the supernova yields, and we have computed again the nucleosynthesis using two or three alternative prescriptions for their rates, taken from the JINA REACLIB database. For the three reactions with the largest sensitivity we have analyzed as well the temperature ranges where a modification of their rates has the strongest effect on nucleosynthesis.Results: The nucleosynthesis resulting from the type Ia supernova models is quite robust with respect to variations of nuclear reaction rates, with the exception of the reaction of fusion of two 12C nuclei. The energy of the explosion changes by less than ˜4% when the rates of the reactions 12C+12C or 16O+16O are multiplied by a factor of ×10 or

  19. Evidence of thermonuclear flame spreading on neutron stars from burst rise oscillations

    SciTech Connect

    Chakraborty, Manoneeta; Bhattacharyya, Sudip E-mail: sudip@tifr.res.in

    2014-09-01

    Burst oscillations during the rising phases of thermonuclear X-ray bursts are usually believed to originate from flame spreading on the neutron star surface. However, the decrease of fractional oscillation amplitude with rise time, which provides a main observational support for the flame spreading model, have so far been reported from only a few bursts. Moreover, the non-detection and intermittent detections of rise oscillations from many bursts are not yet understood considering the flame spreading scenario. Here, we report the decreasing trend of fractional oscillation amplitude from an extensive analysis of a large sample of Rossi X-ray Timing Explorer Proportional Counter Array bursts from 10 neutron star low-mass X-ray binaries. This trend is 99.99% significant for the best case, which provides, to the best of our knowledge, by far the strongest evidence of such a trend. Moreover, it is important to note that an opposite trend is not found in any of the bursts. The concave shape of the fractional amplitude profiles for all the bursts suggests latitude-dependent flame speeds, possibly due to the effects of the Coriolis force. We also systematically study the roles of low fractional amplitude and low count rate for non-detection and intermittent detections of rise oscillations, and attempt to understand them within the flame spreading scenario. Our results support a weak turbulent viscosity for flame spreading, and imply that burst rise oscillations originate from an expanding hot spot, thus making these oscillations a more reliable tool to constrain the neutron star equations of state.

  20. Vulnerability assessment of a space based weapon platform electronics system exposed to a thermonuclear weapon detonation

    SciTech Connect

    Perez, C.L.; Johnson, J.O.

    1994-05-01

    The utilization of reconnaissance/surveillance satellite and weapon platform assets in space will subject the sensitive electronic equipment to a variety of natural and man-made radiation environments. These include Van Allen Belt protons and electrons; galactic and solar flare protons; neutrons, gamma rays, and X-rays from fission and fusion weapons; and directed neutral particle beams and lasers. Electronic equipment, including modem integrated circuits, may undergo permanent or transient changes of the electrical properties of the active components when exposed to these sources of radiation. This report summarizes the results of the Monte Carlo Adjoint Shielding code system -- MASH v1.0 calculations designed to estimate the dose to the critical electronics components of an idealized spaced based weapon platform from neutron and gamma-ray radiation emanating from a thermonuclear weapon detonation. The MASH calculations modeled several source/platform geometry configurations, obtaining results for multiple distances and weapon detonation positions relative to the platform. For certain source/platform orientations, the results indicate vulnerabilities to the C{sup 3} bay critical components box to radiation damage from a nuclear weapon detonation. Neutron protection factors ranged from 0.7 to 3.4 for the three platform configurations analyzed, and gamma-ray protection factors ranged from approximately 1.5 to 9.8. The results further indicate the source has a direct line-of-sight to the critical components box for certain source/platform orientations, regardless of the number of interceptors present. The merits of utilizing the MASH code system for estimating dose and shielding factors for spaced based assets has been demonstrated. The geometry configuration studied here is greatly simplified compared to those that will be encountered in an actual design.