WorldWideScience

Sample records for helium carrier gas

  1. A novel approach to process carbonate samples for radiocarbon measurements with helium carrier gas

    Wacker, L., E-mail: wacker@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Fueloep, R.-H. [Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne (Germany); Hajdas, I. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Molnar, M. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Institute of Nuclear Research, Hungarian Academy of Sciences, 4026 Debrecen (Hungary); Rethemeyer, J. [Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne (Germany)

    2013-01-15

    Most laboratories prepare carbonates samples for radiocarbon analysis by acid decomposition in evacuated glass tubes and subsequent reduction of the evolved CO{sub 2} to graphite in self-made reduction manifolds. This process is time consuming and labor intensive. In this work, we have tested a new approach for the preparation of carbonate samples, where any high-vacuum system is avoided and helium is used as a carrier gas. The liberation of CO{sub 2} from carbonates with phosphoric acid is performed in a similar way as it is often done in stable isotope ratio mass spectrometry where CO{sub 2} is released with acid in septum sealed tube under helium atmosphere. The formed CO{sub 2} is later flushed in a helium flow by means of a double-walled needle mounted from the tubes to the zeolite trap of the automated graphitization equipment (AGE). It essentially replaces the elemental analyzer normally used for the combustion of organic samples. The process can be fully automated from sampling the released CO{sub 2} in the septum-sealed tubes with a commercially available auto-sampler to the graphitization with the automated graphitization. The new method yields in low sample blanks of about 50000 years. Results of processed reference materials (IAEA-C2, FIRI-C) are in agreement with their consensus values.

  2. [Feasibility investigation of hydrogen instead of helium as carrier gas in the determination of five organophosphorus pesticides by gas chromatography-mass spectrometry].

    Liu, Zhenxue; Zhou, Shixue

    2015-01-01

    Helium is almost the only choosable carrier gas used in gas chromatography-mass spectrometry (GC-MS). A mixed standard solution of five organophosphorus pesticides was analyzed by using GC-MS, and hydrogen or helium as carrier gas, so as to study the feasibility of hydrogen instead of helium as carrier gas for the determination of organophosphorus pesticides. Combining a mass spectrum database built by ourselves, the results were deconvolved and identified by Automated Mass Spectral Deconvolution & Identification System (AMDIS32), a software belonging to the workstation of the instrument. Then, the statistical software, IBM SPSS Statistics 19.0 was used for the clustering analysis of the data. The results indicated that when hydrogen was used as carrier gas, the peaks of the pesticides detected were slightly earlier than those when helium used as carrier gas, but the resolutions of the chromatographic peaks were lower, and the fraction good indices (Frac. Good) were lower, too. When hydrogen was used as carrier gas, the signals of the pesticides were unstable, the measuring accuracies of the pesticides were reduced too, and even more, some compounds were undetectable. Therefore, considering the measuring accuracy, the signal stability, and the safety, etc., hydrogen should be cautiously used as carrier gas in the determination of organophosphorus pesticides by GC-MS.

  3. Nitrogen as the carrier gas for helium emission along an active fault in NW Taiwan

    Hong, Wei-Li; Yang, Tsanyao Frank; Walia, Vivek; Lin, Shih-Jung; Fu, Ching-Chou; Chen, Yue-Gau; Sano, Yuji; Chen, Cheng-Hong; Wen, Kuo-Liang

    2010-01-01

    Variations of He gas concentration are widely applied in studies devoted to the location of faults and to monitor seismic activities. Up to now, its migration mechanism in soil is not fully understood. A systematic soil gas survey across an active fault in NW Taiwan provides the opportunity to closely examine the mechanism of He migration in the fault zone. Significant spatial and temporal correlations observed between soil N 2 and He gas support the hypothesis that N 2 is the probable carrier gas for He emission in the studied area. Based on N 2 /Ar ratios and N 2 isotopic results, the excess soil N 2 in this study is considered to be largely derived from ancient atmospheric air which was dissolved in groundwater. Furthermore, observations rule out the possibility of CO 2 being the dominant carrier gas for He in the studied area based on the C and He isotopic compositions and the relationship between concentrations of these gases. At least two soil gas sources, A and B, can be identified in the studied area. Source A is an abiogenic gas source characterized by excess N 2 and He, and very low O 2 and CO 2 content. Source B, on the other hand, is a mixture of biogenic gas and atmospheric air. The development of the fault system is an important factor affecting the degree of mixture between sources A and B. Therefore, variations of soil gas composition, in particular those derived from source A, could be a useful proxy for tracing faults in the area.

  4. The Carrier Gas Pressure Effect in a Laminar Flow Diffusion Chamber, Homogeneous Nucleation of n-Butanol in Helium

    Hyvärinen, A-P.; Brus, David; Ždímal, Vladimír; Smolík, Jiří; Kulmala, M.; Viisanen, V.; Lihavainen, H.

    2006-01-01

    Roč. 124, č. 22 (2006), Art. No. 224304 ISSN 0021-9606 R&D Projects: GA AV ČR(CZ) IAA2076203 Institutional research plan: CEZ:AV0Z40720504 Keywords : supersaturated vapor * cloud chamber * background gas es Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.166, year: 2006

  5. Study on the conversion of H2 and CO from the helium carrier gas of high temperature gas-cooled reactor

    Liao Cuiping; Zheng Zhenhong; Shi Fuen

    1995-01-01

    The conversions of hydrogen and carbon monoxide into water vapor and carbon dioxide on CuO-ZnO-Al 2 O 3 catalyst are studied. The effects of different temperature, system atmospheric pressure, impurity gas concentration, flow and dew point on properties of cupric oxide bed are investigated. The conversion characteristics curves of H 2 and CO are given. Experimental data of conversion capacity, action period and conversion efficiency of CuO-ZnO-Al 2 O 3 are obtained and the optimal parameters are determined. The results show that the concentration of H 2 and CO of the effluent gas after purification can reach below 2 x 10 -6 , respectively. So it can meet the demands of high temperature gas-cooled reactor and also provide optimal design parameters and reliable data for conversion of H 2 and CO on CuO-ZnO-Al 2 O 3 catalyst

  6. On the helium gas leak test

    Nishikawa, Akira; Ozaki, Susumu

    1975-01-01

    The helium gas leak test (Helium mass spectrometer testing) has a leak detection capacity of the highest level in practical leak tests and is going to be widely applied to high pressure vessels, atomic and vacuum equipments that require high tightness. To establish a standard test procedure several series of experiments were conducted and the results were investigated. The conclusions are summarized as follows: (1) The hood method is quantitatively the most reliable method. The leak rate obtained by tests using 100% helium concentration should be the basis of the other method of test. (2) The integrating method, bell jar method, and vacuum spray method can be considered quantitative when particular conditions are satisfied. (3) The sniffer method is not to be considered quantitive. (4) The leak rate of the hood, integrating, and bell jar methods is approximately proportional to the square of the helium partial pressure. (auth.)

  7. LIQUIFIED NATURAL GAS (LNG CARRIERS

    Daniel Posavec

    2010-12-01

    Full Text Available Modern liquefied natural gas carriers are double-bottom ships classified according to the type of LNG tank. The tanks are specially designed to store natural gas cooled to -161°C, the boiling point of methane. Since LNG is highly flammable, special care must be taken when designing and operating the ship. The development of LNG carriers has begun in the middle of the twentieth century. LNG carrier storage space has gradually grown to the current maximum of 260000 m3. There are more than 300 LNG carriers currently in operation (the paper is published in Croatian.

  8. A new helium gas recovery and purification system

    Yamamotot, T.; Suzuki, H.; Ishii, J.; Hamana, I.; Hayashi, S.; Mizutani, S.; Sanjo, S.

    1974-01-01

    A helium gas recovery and purification system, based on the principle of gas permeation through a membrane, is described. The system can be used for the purification of helium gas containing air as a contaminant. The apparatus, operating at ambient temperature does not need constant attention, the recovery ratio of helium gas is satisfactory and running costs are low. Gases other than helium can be processed with the apparatus. (U.K.)

  9. LIQUIFIED NATURAL GAS (LNG) CARRIERS

    Daniel Posavec; Katarina Simon; Matija Malnar

    2010-01-01

    Modern liquefied natural gas carriers are double-bottom ships classified according to the type of LNG tank. The tanks are specially designed to store natural gas cooled to -161°C, the boiling point of methane. Since LNG is highly flammable, special care must be taken when designing and operating the ship. The development of LNG carriers has begun in the middle of the twentieth century. LNG carrier storage space has gradually grown to the current maximum of 260000 m3. There are more than 300 L...

  10. Gas turbine modular helium reactor in cogeneration

    Leon de los Santos, G.

    2009-10-01

    This work carries out the thermal evaluation from the conversion of nuclear energy to electric power and process heat, through to implement an outline gas turbine modular helium reactor in cogeneration. Modeling and simulating with software Thermo flex of Thermo flow the performance parameters, based on a nuclear power plant constituted by an helium cooled reactor and helium gas turbine with three compression stages, two of inter cooling and one regeneration stage; more four heat recovery process, generating two pressure levels of overheat vapor, a pressure level of saturated vapor and one of hot water, with energetic characteristics to be able to give supply to a very wide gamma of industrial processes. Obtaining a relationship heat electricity of 0.52 and efficiency of net cogeneration of 54.28%, 70.2 MW net electric, 36.6 MW net thermal with 35% of condensed return to 30 C; for a supplied power by reactor of 196.7 MW; and with conditions in advanced gas turbine of 850 C and 7.06 Mpa, assembly in a shaft, inter cooling and heat recovery in cogeneration. (Author)

  11. Use of separating nozzles or ultra-centrifuges for obtaining helium from gas mixtures containing helium

    Reimann, T.

    1987-01-01

    To obtain helium from gas mixtures containing helium, particularly from natural gas, it is proposed to match the dimensions of the separation devices for a ratio of the molecular weights to be separated of 4:1 of more, which ensures a higher separation factor and therefore a smaller number of separation stages to be connected in series. The process should make reasonably priced separation of helium possible. (orig./HP) [de

  12. Cooling performance of helium-gas/water coolers in HENDEL

    Inagaki, Yoshiyuki; Takada, Shoji; Hayashi, Haruyoshi; Kobayashi, Toshiaki; Ohta, Yukimaru; Shimomura, Hiroaki; Miyamoto, Yoshiaki

    1994-01-01

    The helium engineering demonstration loop (HENDEL) has four helium-gas/water coolers where the cooling water flows in the tubes and helium gas on the shell side. Their cooling performance was studied using the operational data from 1982 to 1991. The heat transfer of helium gas on the shell was obtained for segmental and step-up baffle type coolers. Also, the change with operation time was investigated. The cooling performance was lowered by the graphite powder released from the graphite components for several thousand hours and thereafter recovered because the graphite powder from the components was reduced and the powder in the cooler shell was blown off during the operation. (orig.)

  13. A review of helium gas turbine technology for high-temperature gas-cooled reactors

    No, Hee Cheon; Kim, Ji Hwan; Kim, Hyeun Min

    2007-01-01

    Current High-Temperature Gas-cooled Reactors (HTGRs) are based on a closed brayton cycle with helium gas as the working fluid. Thermodynamic performance of the axial-flow helium gas turbines is of critical concern as it considerably affects the overall cycle efficiency. Helium gas turbines pose some design challenges compared to steam or air turbomachinery because of the physical properties of helium and the uniqueness of the operating conditions at high pressure with low pressure ratio. This report present a review of the helium Brayton cycle experiences in Germany and in Japan. The design and availability of helium gas turbines for HTGR are also presented in this study. We have developed a new throughflow calculation code to calculate the design-point performance of helium gas turbines. Use of the method has been illustrated by applying it to the GTHTR300 reference

  14. Organ protection by the noble gas helium

    Smit, K.F.

    2017-01-01

    The aims of this thesis were to investigate whether helium induces preconditioning in humans, and to elucidate the mechanisms behind this possible protection. First, we collected data regarding organ protective effects of noble gases in general, and of helium in particular (chapters 1-3). In chapter

  15. Helium gas purity monitor based on low frequency acoustic resonance

    Kasthurirengan, S.; Jacob, S.; Karunanithi, R.; Karthikeyan, A.

    1996-05-01

    Monitoring gas purity is an important aspect of gas recovery stations where air is usually one of the major impurities. Purity monitors of Katherometric type are commercially available for this purpose. Alternatively, we discuss here a helium gas purity monitor based on acoustic resonance of a cavity at audio frequencies. It measures the purity by monitoring the resonant frequency of a cylindrical cavity filled with the gas under test and excited by conventional telephone transducers fixed at the ends. The use of the latter simplifies the design considerably. The paper discusses the details of the resonant cavity and the electronic circuit along with temperature compensation. The unit has been calibrated with helium gas of known purities. The unit has a response time of the order of 10 minutes and measures the gas purity to an accuracy of 0.02%. The unit has been installed in our helium recovery system and is found to perform satisfactorily.

  16. 21 CFR 868.1640 - Helium gas analyzer.

    2010-04-01

    ... mixture during pulmonary function testing. The device may use techniques such as thermal conductivity, gas... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Helium gas analyzer. 868.1640 Section 868.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...

  17. Maintenance free gas bearing helium blower for nuclear plant

    Molyneaux, A., Dr; Harris, M., Prof; Sharkh, S., Prof; Hill, S.; de Graaff, T.

    2017-08-01

    This paper describes the design, testing and operation of novel helium blowers used to recirculate the helium blanketing gas in the nuclear reactor used as a neutron source at the Institut Laue Langevan, Grenoble, France. The laser sintered shrouded centrifugal wheel operates at speeds up to 45000 rpm supported on helium lubricated hydrodynamic spiral groove bearings, and is driven by a sensorless permanent magnet motor. The entire machine is designed to keep the helium gas (polluted by a small amount of D2O) out of contact with any iron or copper materials which would contribute to the corrosion of parts of the circuit. It is designed to have zero maintenance during a lifetime of 40,000 hours of continuous operation. This paper will describe the spiral groove journal and thrust bearings. Design and manufacture of the 1 kW motor and centrifugal wheel will be explained including their CFD and FEA analyses. Measurements of rotor displacement will be presented showing the behaviour under factory testing as well as details of the measured centrifugal wheel and motor performances. Two machines are incorporated into the circuit to provide redundancy and the first blower has been in continuous operation since Jan 2015. The blower was designed, manufactured, assembled and tested in the UK using predominantly UK suppliers.

  18. Elevated temperature and high pressure large helium gas loop

    Sakasai, Minoru; Midoriyama, Shigeru; Miyata, Toyohiko; Nakase, Tsuyoshi; Izaki, Makoto

    1979-01-01

    The development of high temperature gas-cooled reactors especially aiming at the multi-purpose utilization of nuclear heat energy is carried out actively in Japan and West Germany. In Japan, the experimental HTGR of 50 MWt and 1000 deg C outlet temperature is being developed by Japan Atomic Energy Research Institute and others since 1969, and the development of direct iron-making technology utilizing high temperature reducing gas was started in 1973 as the large project of Ministry of Internalional Trade and Industry. Kawasaki Heavy Industries, Ltd., Has taken part in these development projects, and has developed many softwares for nuclear heat design, system design and safety design of nuclear reactor system and heat utilization system. In hardwares also, efforts have been exerted to develop the technologies of design and manufacture of high temperature machinery and equipments. The high temperature, high pressure, large helium gas loop is under construction in the technical research institute of the company, and it is expected to be completed in December, 1979. The tests planned are that of proving the dynamic performances of the loop and its machinery and equipments and the verification of analysis codes. The loop is composed of the main circulation system, the objects of testing, the helium gas purifying system, the helium supplying and evacuating system, instruments and others. (Kako, I.)

  19. Helium gas turbine conceptual design by genetic/gradient optimization

    Yang, Long; Yu, Suyuan

    2003-01-01

    Helium gas turbine is the key component of the power conversion system for direct cycle High Temperature Gas-cooled Reactors (HTGR), of which an optimal design is essential for high efficiency. Gas turbine design currently is a multidisciplinary process in which the relationships between constraints, objective functions and variables are very noisy. Due to the ever-increasing complexity of the process, it has becomes very hard for the engineering designer to foresee the consequences of changing certain parts. With classic design procedures which depend on adaptation to baseline design, this problem is usually averted by choosing a large number of design variables based on the engineer's judgment or experience in advance, then reaching a solution through iterative computation and modification. This, in fact, leads to a reduction of the degree of freedom of the design problem, and therefore to a suboptimal design. Furthermore, helium is very different in thermal properties from normal gases; it is uncertain whether the operation experiences of a normal gas turbine could be used in the conceptual design of a helium gas turbine. Therefore, it is difficult to produce an optimal design with the general method of adaptation to baseline. Since their appearance in the 1970s, Genetic algorithms (GAs) have been broadly used in many research fields due to their robustness. GAs have also been used recently in the design and optimization of turbo-machines. Researchers at the General Electronic Company (GE) developed an optimization software called Engineous, and used GAs in the basic design and optimization of turbines. The ITOP study group from Xi'an Transportation University also did some work on optimization of transonic turbine blades. However, since GAs do not have a rigorous theory base, many problems in utilities have arisen, such as premature convergence and uncertainty; the GA doesn't know how to locate the optimal design, and doesn't even know if the optimal solution

  20. 43 CFR 16.1 - Agreements to dispose of helium in natural gas.

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Agreements to dispose of helium in natural gas. 16.1 Section 16.1 Public Lands: Interior Office of the Secretary of the Interior CONSERVATION OF HELIUM § 16.1 Agreements to dispose of helium in natural gas. (a) Pursuant to his authority and...

  1. Superconducting cable cooling system by helium gas at two pressures

    Dean, J.W.

    1977-01-01

    Thermally contacting, oppositely streaming, cryogenic fluid streams in the same enclosure in a closed cycle changes the fluid from a cool high pressure helium gas to a cooler reduced pressure helium gas in an expander so as to be at different temperature ranges and pressures respectively in go and return legs that are in thermal contact with each other and in thermal contact with a longitudinally extending superconducting transmission line enclosed in the same cable enclosure that insulates the line from the ambient at a temperature T 1 . By first circulating the fluid from a refrigerator at one end of the line as a cool gas at a temperature range T 2 to T 3 in the go leg, then circulating the gas through an expander at the other end of the line where the gas becomes a cooler gas at a reduced pressure and at a reduced temperature T 4 and finally by circulating the cooler gas back again to the refrigerator in a return leg at a temperature range T 4 to T 5 , while in thermal contact with the gas in the go leg, and in the same enclosure therewith for compression into a higher pressure gas at T 2 in a closed cycle, where T 2 greater than T 3 and T 5 greater than T 4 , the fluid leaves the enclosure in the go leg as a gas at its coldest point in the go leg, and the temperature distribution is such that the line temperature decreases along its length from the refrigerator due to the cooling from the gas in the return leg

  2. Study on fundamental features of helium turbomachine for high temperature gas-cooled reactor

    Wang Jie; Gu Yihua

    2004-01-01

    The High temperature gas-cooled reactor (HTGR) coupled with helium turbine cycle is considered as one of the leading candidates for future nuclear power plants. The HTGR helium turbine cycle was analyzed and optimized. Then the focal point of investigation was concentrated on the fundamental thermodynamic and aerodynamic features of helium turbomachine. As a result, a helium turbomachine is different from a general combustion gas turbine in two main design features, that is a helium turbomachine has more blade stages and shorter blade length, which are caused by the helium property and the high pressure of a closed cycle, respectively. (authors)

  3. A High Reliability Gas-driven Helium Cryogenic Centrifugal Compressor

    Bonneton, M; Gistau-Baguer, Guy M; Turcat, F; Viennot, P

    1998-01-01

    A helium cryogenic compressor was developed and tested in real conditions in 1996. The achieved objective was to compress 0.018 kg/s Helium at 4 K @ 1000 Pa (10 mbar) up to 3000 Pa (30 mbar). This project was an opportunity to develop and test an interesting new concept in view of future needs. The main features of this new specific technology are described. Particular attention is paid to the gas bearing supported rotor and to the pneumatic driver. Trade off between existing technologies and the present work are presented with special stress on the bearing system and the driver. The advantages are discussed, essentially focused on life time and high reliability without maintenance as well as non pollution characteristic. Practical operational modes are also described together with the experimental performances of the compressor. The article concludes with a brief outlook of future work.

  4. Adsorption of helium gas near Tλ at low pressures

    Kachalin, G.V.; Kryukov, A.P.; Nesterov, S.B.

    1998-01-01

    Cryosorption of helium isotopes ( 4 He and 3 He) on thin argon cryo layers is studied experimentally in the temperature range 4.2-2 K at low pressures. It is shown that the sorption iso stere 4 He is anomalous at temperatures close to be temperature of the phase transition in the bulk of 4 He, T λ . An abrupt pressure change is observed for a 4 He film thickness approximately equal to two monolayers. The experiments on cryosorption of 3 He gas on an argon layer with a 3 He film thickness of approximately one monolayer display monotonous changes in the pressure within the whole temperature range

  5. Evaluation of the Gas Turbine Modular Helium Reactor

    1994-02-01

    Recent advances in gas-turbine and heat exchanger technology have enhanced the potential for a Modular Helium Reactor (MHR) incorporating a direct gas turbine (Brayton) cycle for power conversion. The resulting Gas Turbine Modular Helium Reactor (GT-MHR) power plant combines the high temperature capabilities of the MHR with the efficiency and reliability of modern gas turbines. While the passive safety features of the steam cycle MHR (SC-MHR) are retained, generation efficiencies are projected to be in the range of 48% and steam power conversion systems, with their attendant complexities, are eliminated. Power costs are projected to be reduced by about 20%, relative to the SC-MHR or coal. This report documents the second, and final, phase of a two-part evaluation that concluded with a unanimous recommendation that the direct cycle (DC) variant of the GT-MHR be established as the commercial objective of the US Gas-Cooled Reactor Program. This recommendation has been endorsed by industrial and utility participants and accepted by the US Department of Energy (DOE). The Phase II effort, documented herein, concluded that the DC GT-MHR offers substantial technical and economic advantages over both the IDC and SC systems. Both the DC and IDC were found to offer safety advantages, relative to the SC, due to elimination of the potential for water ingress during power operations. This is the dominant consequence event for the SC. The IDC was judged to require somewhat less development than the direct cycle, while the SC, which has the greatest technology base, incurs the least development cost and risk. While the technical and licensing requirements for the DC were more demanding, they were judged to be incremental and feasible. Moreover, the DC offers significant performance and cost improvements over the other two concepts. Overall, the latter were found to justify the additional development needs.

  6. Evaluation of the Gas Turbine Modular Helium Reactor

    1994-02-01

    Recent advances in gas-turbine and heat exchanger technology have enhanced the potential for a Modular Helium Reactor (MHR) incorporating a direct gas turbine (Brayton) cycle for power conversion. The resulting Gas Turbine Modular Helium Reactor (GT-MHR) power plant combines the high temperature capabilities of the MHR with the efficiency and reliability of modern gas turbines. While the passive safety features of the steam cycle MHR (SC-MHR) are retained, generation efficiencies are projected to be in the range of 48% and steam power conversion systems, with their attendant complexities, are eliminated. Power costs are projected to be reduced by about 20%, relative to the SC-MHR or coal. This report documents the second, and final, phase of a two-part evaluation that concluded with a unanimous recommendation that the direct cycle (DC) variant of the GT-MHR be established as the commercial objective of the US Gas-Cooled Reactor Program. This recommendation has been endorsed by industrial and utility participants and accepted by the US Department of Energy (DOE). The Phase II effort, documented herein, concluded that the DC GT-MHR offers substantial technical and economic advantages over both the IDC and SC systems. Both the DC and IDC were found to offer safety advantages, relative to the SC, due to elimination of the potential for water ingress during power operations. This is the dominant consequence event for the SC. The IDC was judged to require somewhat less development than the direct cycle, while the SC, which has the greatest technology base, incurs the least development cost and risk. While the technical and licensing requirements for the DC were more demanding, they were judged to be incremental and feasible. Moreover, the DC offers significant performance and cost improvements over the other two concepts. Overall, the latter were found to justify the additional development needs

  7. Transient heat transfer for forced convection flow of helium gas

    Liu, Qiusheng; Fukuda, Katsuya; Sasaki, Kenji; Yamamoto, Manabu

    1999-01-01

    Transient heat transfer coefficients for forced convection flow of helium gas over a horizontal cylinder were measured using a forced convection test loop. The platinum heater with a diameter of 1.0 mm was heated by electric current with an exponential increase of Q 0 exp(t/τ). It was clarified that the heat transfer coefficient approaches the steady-state one for the period τ over 1 s, and it becomes higher for the period of τ shorter than 1 s. The transient heat transfer shows less dependent on the gas flowing velocity when the period becomes very shorter. Semi-empirical correlations for steady-state and transient heat transfer were developed based on the experimental data. (author)

  8. Consideration of heat transfer performance of helium-gas/water coolers in HENDEL

    Inagaki, Yoshiyuki; Miyamoto, Yoshiaki

    1986-10-01

    The helium engineering loop (HENDEL) has four helium-gas/water coolers, where the cooling water flows in the tubes and the helium gas flows on the shell side. Their cooling performance depends on mainly the heat transfer of helium gas on the shell side. This report describes the operational data of the coolers and the consideration of the heat transfer performance which is important for the design of coolers. It becomes clear that Donohue's equation is close to the operational data and conservative for the segmental baffle type cooler and preduction by Fishenden-Saunders or Zukauskas' equation is conservation for the step-up baffle type cooler. (author)

  9. Behavior of helium gas atoms and bubbles in low activation 9Cr martensitic steels

    Hasegawa, Akira; Shiraishi, Haruki; Matsui, Hideki; Abe, Katsunori

    1994-09-01

    The behavior of helium-gas release from helium-implanted 9Cr martensitic steels (500 appm implanted at 873 K) during tensile testing at 873 K was studied. Modified 9Cr-1Mo, low-activation 9Cr-2W and 9Cr-0.5V were investigated. Cold-worked AISI 316 austenitic stainless steel was also investigated as a reference which was susceptible helium embrittlement at high temperature. A helium release peak was observed at the moment of rupture in all the specimens. The total quantity of helium released from these 9Cr steels was in the same range but smaller than that of 316CW steel. Helium gas in the 9Cr steels should be considered to remain in the matrix at their lath-packets even if deformed at 873 K. This is the reason why the martensitic steels have high resistance to helium embrittlement.

  10. A description of bubble growth and gas release of helium implanted tungsten

    Sharafat, S.; Hu, Q.; Ghoniem, N.; Tkahashi, A.

    2007-01-01

    Full text of publication follows: Bubble growth and gas release during annealing of helium implanted tungsten is described using a Kinetic Monte Carlo approach. The implanted spatial profiles of stable bubble nuclei are first determined using the Kinetic Rate Theory based helium evolution code, HEROS. The effects of implantation energy, temperature, and bias forces, such as temperature- and stress gradients on bubble migration and coalescence are investigated to explain experimental gas release measurements. This comprehensive helium bubble evolution and release model, demonstrates the impact of near surface (< 1 um) versus deep helium implantation on bubble evolution. Near surface implanted helium bubbles readily attain large equilibrium sizes, while matrix bubbles remain small with high helium pressures. Using the computer simulation, the various stages of helium bubble nucleation, growth, coalescence, and migration are demonstrated and compared with available experimental results. (authors)

  11. Behavior of helium gas atoms and bubbles in low activation 9Cr martensitic steels

    Hasegawa, Akira; Shiraishi, Haruki; Matsui, Hideki; Abe, Katsunori

    1994-01-01

    The behavior of helium-gas release from helium-implanted 9Cr martensitic steels (500 appm implanted at 873 K) during tensile testing at 873 K was studied. Modified 9Cr-1Mo, low-activation 9Cr-2W and 9Cr-0.5V were investigated. Cold-worked AISI 316 austenitic stainless steel was also investigated as a reference which was susceptible helium embrittlement at high temperature. A helium release peak was observed at the moment of rupture in all the specimens. The total quantity of helium released from these 9Cr steels was in the same range but smaller than that of 316CW steel. Helium gas in the 9Cr steels should be considered to remain in the matrix at their lath-packets even if deformed at 873 K. This is the reason why the martensitic steels have high resistance to helium embrittlement. ((orig.))

  12. Helium turbomachinery operating experience from gas turbine power plants and test facilities

    McDonald, Colin F.

    2012-01-01

    The closed-cycle gas turbine, pioneered and deployed in Europe, is not well known in the USA. Since nuclear power plant studies currently being conducted in several countries involve the coupling of a high temperature gas-cooled nuclear reactor with a helium closed-cycle gas turbine power conversion system, the experience gained from operated helium turbomachinery is the focus of this paper. A study done as early as 1945 foresaw the use of a helium closed-cycle gas turbine coupled with a high temperature gas-cooled nuclear reactor, and some two decades later this was investigated but not implemented because of lack of technology readiness. However, the first practical use of helium as a gas turbine working fluid was recognized for cryogenic processes, and the first two small fossil-fired helium gas turbines to operate were in the USA for air liquefaction and nitrogen production facilities. In the 1970's a larger helium gas turbine plant and helium test facilities were built and operated in Germany to establish technology bases for a projected future high efficiency large nuclear gas turbine power plant concept. This review paper covers the experience gained, and the lessons learned from the operation of helium gas turbine plants and related test facilities, and puts these into perspective since over three decades have passed since they were deployed. An understanding of the many unexpected events encountered, and how the problems, some of them serious, were resolved is important to avoid them being replicated in future helium turbomachines. The valuable lessons learned in the past, in many cases the hard way, particularly from the operation in Germany of the Oberhausen II 50 MWe helium gas turbine plant, and the technical know-how gained from the formidable HHV helium turbine test facility, are viewed as being germane in the context of current helium turbomachine design work being done for future high efficiency nuclear gas turbine plant concepts. - Highlights:

  13. The early history of high-temperature helium gas-cooled nuclear power reactors

    Simnad, M.T.; California Univ., San Diego, La Jolla, CA

    1991-01-01

    The original concepts in the proposals for high-temperature helium gas-cooled power reactors by Farrington Daniels, during the decade 1944-1955, are summarized. The early research on the development of the helium gas-cooled power reactors is reviewed, and the operational experiences with the first generation of HTGRs are discussed. (author)

  14. Conceptual design of helium gas turbine for MHTGR-GT

    Matsuo, E.; Tsutsumi, M.; Ogata, K.; Nomura, S.

    1996-01-01

    Conceptual designs of the direct-cycle helium gas turbine for a practical unit (450 MWt) and an experimental unit (1200kWt) of MHTGR were conducted and the results as shown below were obtained. The power conversion vessel for this practical unit can further be downsized to an outside diameter of 7.4m and a height of 22m as compared with the conventional design examples. Comparison of the conceptual designs of helium gas turbines using single-shaft type employing the axial-flow compressor and twin-shaft type employing the centrifugal compressor shows that the former provides advantages in terms of structure and control designs whereas the latter offers a higher efficiency. In order to determine which of them should be selected, a further study to investigate various aspects of safety features and startup characteristics will be needed. Either of the two types can provide a cycle efficiency of 46 to 48%. The third mode natural frequencies of the twin-shart type's low-pressure rotational shaft and the single shaft type are below the designed rotational speed, but their vibrational controls are made available using the magnetic bearing system. Elevation of the natural frequency for the twin-shaft type would be possible by altering the arrangements of its shafting configuration. As compared with the earlier conceptual designs, the overall systems configuration can be made simpler and more compact; five stages of turbines for the single-shaft type and seven stages of turbines for the twin-shaft type employing one shaft for the low-pressure compressor and the power turbine and; 26 stages of compressors for the axial-flow type with the single shaft system and five stages of compressors for the centrifugal type with the twin-shaft system. 9 refs, 12 figs, 4 tabs

  15. Helium production technology based on natural gas combustion and beneficial use of thermal energy

    Nakoryakov Vladimir E.

    2016-01-01

    Full Text Available Helium is widely used in all industries, including power plant engineering. In recent years, helium is used in plants operating by the Brayton cycle, for example, in the nuclear industry. Using helium-xenon mixture in nuclear reactors has a number of advantages, and this area is rapidly developing. The hydrodynamics and mass transfer processes in single tubes with various cross-sections as well as in inter-channel space of heating tube bundle were studied at the Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences. Currently, there is a strongest shortage in helium production. The main helium production method consists in the liquefaction of the natural gas and subsequent separation of helium from remaining gas with its further purification using membranes.

  16. Helium heater design for the helium direct cycle component test facility. [for gas-cooled nuclear reactor power plant

    Larson, V. R.; Gunn, S. V.; Lee, J. C.

    1975-01-01

    The paper describes a helium heater to be used to conduct non-nuclear demonstration tests of the complete power conversion loop for a direct-cycle gas-cooled nuclear reactor power plant. Requirements for the heater include: heating the helium to a 1500 F temperature, operating at a 1000 psia helium pressure, providing a thermal response capability and helium volume similar to that of the nuclear reactor, and a total heater system helium pressure drop of not more than 15 psi. The unique compact heater system design proposed consists of 18 heater modules; air preheaters, compressors, and compressor drive systems; an integral control system; piping; and auxiliary equipment. The heater modules incorporate the dual-concentric-tube 'Variflux' heat exchanger design which provides a controlled heat flux along the entire length of the tube element. The heater design as proposed will meet all system requirements. The heater uses pressurized combustion (50 psia) to provide intensive heat transfer, and to minimize furnace volume and heat storage mass.

  17. Gas turbine modular helium reactor in cogeneration; Turbina de gas reactor modular con helio en cogeneracion

    Leon de los Santos, G. [UNAM, Facultad de Ingenieria, Division de Ingenieria Electrica, Departamento de Sistemas Energeticos, Ciudad Universitaria, 04510 Mexico, D. F. (Mexico)], e-mail: tesgleon@gmail.com

    2009-10-15

    This work carries out the thermal evaluation from the conversion of nuclear energy to electric power and process heat, through to implement an outline gas turbine modular helium reactor in cogeneration. Modeling and simulating with software Thermo flex of Thermo flow the performance parameters, based on a nuclear power plant constituted by an helium cooled reactor and helium gas turbine with three compression stages, two of inter cooling and one regeneration stage; more four heat recovery process, generating two pressure levels of overheat vapor, a pressure level of saturated vapor and one of hot water, with energetic characteristics to be able to give supply to a very wide gamma of industrial processes. Obtaining a relationship heat electricity of 0.52 and efficiency of net cogeneration of 54.28%, 70.2 MW net electric, 36.6 MW net thermal with 35% of condensed return to 30 C; for a supplied power by reactor of 196.7 MW; and with conditions in advanced gas turbine of 850 C and 7.06 Mpa, assembly in a shaft, inter cooling and heat recovery in cogeneration. (Author)

  18. Influence of Carrier Gas Composition on the Stress of Al₂O₃ Coatings Prepared by the Aerosol Deposition Method.

    Schubert, Michael; Exner, Jörg; Moos, Ralf

    2014-08-05

    Al₂O₃ films were prepared by the aerosol deposition method at room temperature using different carrier gas compositions. The layers were deposited on alumina substrates and the film stress of the layer was calculated by measuring the deformation of the substrate. It was shown that the film stress can be halved by using oxygen instead of nitrogen or helium as the carrier gas. The substrates were annealed at different temperature steps to gain information about the temperature dependence of the reduction of the implemented stress. Total relaxation of the stress can already be achieved at 300 °C. The XRD pattern shows crystallite growth and reduction of microstrain while annealing.

  19. Unexpected mobility of OH+ and OD+ molecular ions in cooled helium gas

    Isawa, R; Yamazoe, J; Tanuma, H; Ohtsuki, K

    2012-01-01

    Mobilities of OH + and OD + ions in cooled helium gas have been measured at gas temperature of 4.3 K. Measured mobilities of both ions as a function of an effective temperature T eff show a minimum around 80 K, and they are approaching to the polarization limits at very low T eff . These findings will be related to the extremely strong anisotropy of the interaction potential between the molecular ion and helium atom.

  20. Preliminary study on helium turbomachine for high temperature gas-cooled reactor

    Chen Yihua; Wang Jie; Zhang Zuoyi

    2003-01-01

    In the high temperature gas-cooled reactor (HTGR), gas turbine cycle is a new concept in the field of nuclear power. It combines two technologies of HTGR and gas turbine cycle, which represent the state-of-the-art technologies of nuclear power and fossil fuel generation respectively. This approach is expected to improve safety and economy of nuclear power plant significantly. So it is a potential scheme with competitiveness. The heat-recuperated cycle is the main stream of gas turbine cycle. In this cycle, the work medium is helium, which is very different from the air, so that the design features of the helium turbomachine and combustion gas turbomachine are different. The paper shows the basic design consideration for the heat-recuperated cycle as well as helium turbomachine and highlights its main design features compared with combustion gas turbomachine

  1. The real gas behaviour of helium as a cooling medium for high-temperature reactors

    Hewing, G.

    1977-01-01

    The article describes the influence of the real gas behaviour on the variables of state for the helium gas and the effects on the design of high-temperature reactor plants. After explaining the basic equations for describing variables and changes of state of the real gas, the real and ideal gas behaviour is analysed. Finally, the influence of the real gas behaviour on the design of high-temperature reactors in one- and two-cycle plants is investigated. (orig.) [de

  2. The distribution of helium isotopes of natural gas and tectonic environment

    Sun Mingliang; Tao Mingxin

    1993-01-01

    Based on the 3 He/ 4 He data of the main oil-gas bearing basins in continental China, a systematic study has been made for the first time on the relations between the space distribution of the helium isotopes of natural gas and the tectonic environment. The average value R-bar of 3 He/ 4 He in eastern China bordering on the Pacific Ocean is 2.08 x 10 -6 >Ra, and that is dualistic mixed helium containing mantle source helium. The R-bar of central and western China is 4.96 x 10 -8 , and that is mainly crust source radioactive helium. The R-bar of Huabei and Zhongyuan oil-gas fields is 8.00 x 10 -7 , and that is a kind of transitional helium intercepted between the eastern region and the central western region of China. On the whole, the 3 He/ 4 He values decrease gradually with the distance from the subduction zone of the Western Pacific Ocean. The results show that the space distributions of the helium isotopes is controlled by the tectonic environment, that is the environment of tensile rift, especially in the neighborhood of deep megafractures advantageous to the rise of mantle source helium, so then and there the 3 He/ 4 He value is the highest; In the most stable craton basins, the value is the lowest and the helium is a typical crust source radioactive one. Between the active area (rift) and stable area, there is the transitional helium and its value is 10 -7 , as is the case in Huabei-Zhongyuan oil-gas field

  3. The Gas Turbine - Modular Helium Reactor: A Promising Option for Near Term Deployment

    LaBar, Malcolm P.

    2002-01-01

    The Gas Turbine - Modular Helium Reactor (GT-MHR) is an advanced nuclear power system that offers unparalleled safety, high thermal efficiency, environmental advantages, and competitive electricity generation costs. The GT-MHR module couples a gas-cooled modular helium reactor (MHR) with a high efficiency modular Brayton cycle gas turbine (GT) energy conversion system. The reactor and power conversion systems are located in a below grade concrete silo that provides protection against sabotage. The GT-MHR safety is achieved through a combination of inherent safety characteristics and design selections that take maximum advantage of the gas-cooled reactor coated particle fuel, helium coolant and graphite moderator. The GT-MHR is projected to be economically competitive with alternative electricity generation technologies due to the high operating temperature of the gas-cooled reactor, high thermal efficiency of the Brayton cycle power conversion system, high fuel burnup (>100,000 MWd/MT), and low operation and maintenance requirements. (author)

  4. Determination of low levels of krypton in helium by gas chromatography

    Evans, D.L.; Mukherji, A.K.

    1980-01-01

    Krypton-helium mixture was used as an adsorbate for surface area measurement--. The surface area measurements depend on the accuracy with which the krypton concentration is known. Generally gas tanks supplied by Union Carbide provide a nominal value of 0.1% krypton in helium. The surface area measurements require, however, that the krypton concentraion be known to +- 0.001% or better. A standard plot of krypton volume in microliters vs the area under the curve as measured by a planimeter using the helium detector and Molecular Sieve 5A column was obtained. Results with a thermal conductivity detector using Molecular Sieve 5A and Carbon Molecular Sieve are also given. Low levels of krypton in helium can be measured with precision using either a helium or a thermal conductivity detector with Molecular Sieve 5A or Carbon Molecular Sieve columns. 2 figures, 1 table

  5. General characteristics and technical subjects on helium closed cycle gas turbine

    Shimomura, Hiroaki

    1996-06-01

    Making the subjects clarified on nuclear-heated gas turbine that will apply the inherent features of HTGR, the present paper discusses the difference of the helium closed cycle gas turbine, which is a candidate of nuclear gas turbine, with the open cycle gas turbine and indicates inherent problems of closed cycle gas turbine, its effects onto thermal efficiency and turbine output and difficulties due to the pressure ratio and specific speed from use of helium. The paper also discusses effects of the external pressure losses onto the efficiencies of compressor and turbine that are major components of the gas turbine. According to the discussions above, the paper concludes indicating the key idea on heat exchangers for the closed cycle gas turbine and design basis to solve the problems and finally offers new gas turbine conception using nitrogen or air that is changeable into open cycle gas turbine. (author)

  6. Analysis of a multicomponent gas absorption system with carrier gas coabsorption

    Merriman, J.R.

    1975-03-01

    Conventional integrated versions of the packed gas absorber design equations do not account for significant coabsorption of the carrier gas along with the dilute transferring species. These equations, as a result, also neglect the relationship between dilute component transfer and carrier gas coabsorption. In the absorption of Kr and Xe from various carrier gases, using CCl 2 F 2 as the process solvent, carrier coabsorption is substantial. Consequently, a design package was developed to deal with multicomponent gas absorption in systems characterized by carrier gas coabsorption. Developed within the general film theory framework, the basic feature of this design approach is a view of dilute component mass-transfer as a conventional diffusive transfer superimposed on a net flux caused by carrier absorption. Other supporting elements of the design package include predictive techniques for various fluid properties, estimating procedures for carrier gas equilibrium constants, and correlations for carrier gas and dilute gas mass-transfer coefficients. When applied to systems using CCl 2 F 2 as the solvent; He, N 2 , air, or Ar as the carrier gas; and Kr or Xe as the dilute gas; the design approach gave good results, even when extended to conditions well beyond those of its development. (U.S.)

  7. Feasibility of high-helium natural gas exploration in the Presinian strata, Sichuan Basin

    Jian Zhang

    2015-01-01

    Full Text Available Helium in China highly depends on import at present, so the most practical way to change the situation is searching for medium-to-large natural gas fields with high helium content. Therefore, the hydrocarbon accumulation mechanism and the helium origin of the Weiyuan high-helium natural gas reservoir have been analyzed to find out the feasibility of finding natural gas field with high helium content in the Presinian strata of the Sichuan Basin. Based on twelve outcrop sections and drilling data of four wells encountering the Presinian strata, the petrological features, sedimentary facies and source rocks of Presinian strata were systematically analyzed, which shows that the sedimentary formation developed in the Presinian is the Nanhua system, and the stratigraphic sequence revealed by outcrop section in the eastern margin includes the Nantuo, Datangpo, Gucheng and Liantuo Fms, and it is inferred that the same stratigraphic sequence may occur inside the basin. The Nantuo, Gucheng and Liantuo Fms are mainly glacial deposits of glutenite interbedded with mudstone; the Datangpo Fm is interglacial deposits of sandstone and shale, the lower part shale, rich in organic matter, is fairly good source rock. Further study showed that the Nantuo coarse-grained clastic reservoir, Datangpo source rock and the intruded granite “helium source rock” make up a good high-helium gas system. Controlled by the early rift, the thick Presinian sedimentary rocks occur primarily inside the rift. The distribution of sedimentary rocks and granite in the basin was predicted by use of the seismic data, which shows that the feasibility of finding high-helium gas reservoirs in Ziyang area of the Sichuan Basin is great.

  8. Program for aerodynamic performance tests of helium gas compressor model of the gas turbine high temperature reactor (GTHTR300)

    Takada, Shoji; Takizuka, Takakazu; Kunimoto, Kazuhiko; Yan, Xing; Itaka, Hidehiko; Mori, Eiji

    2003-01-01

    Research and development program for helium gas compressor aerodynamics was planned for the power conversion system of the Gas Turbine High Temperature Reactor (GTHTR300). The axial compressor with polytropic efficiency of 90% and surge margin more than 30% was designed with 3-dimensional aerodynamic design. Performance and surge margin of the helium gas compressor tends to be lower due to the higher boss ratio which makes the tip clearance wide relative to the blade height, as well as due to a larger number of stages. The compressor was designed on the basis of methods and data for the aerodynamic design of industrial open-cycle gas-turbine. To validate the design of the helium gas compressor of the GTHTR300, aerodynamic performance tests were planned, and a 1/3-scale, 4-stage compressor model was designed. In the tests, the performance data of the helium gas compressor model will be acquired by using helium gas as a working fluid. The maximum design pressure at the model inlet is 0.88 MPa, which allows the Reynolds number to be sufficiently high. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

  9. Skin blood flow from gas transport: helium xenon and laser Doppler compared

    Neufeld, G.R.; Galante, S.R.; Whang, J.M.; DeVries, D.; Baumgardner, J.E.; Graves, D.J.; Quinn, J.A.

    1988-01-01

    A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics

  10. Skin blood flow from gas transport: helium xenon and laser Doppler compared

    Neufeld, G.R.; Galante, S.R.; Whang, J.M.; DeVries, D.; Baumgardner, J.E.; Graves, D.J.; Quinn, J.A.

    1988-03-01

    A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics.

  11. Advanced Gas Cooled Reactor Materials Program. Reducing helium impurity depletion in HTGR materials testing

    Baldwin, D.H.

    1984-08-01

    Moisture depletion in HTGR materials testing rigs has been empirically studied in the GE High Temperature Reactor Materials Testing Laboratory (HTRMTL). Tests have shown that increased helium flow rates and reduction in reactive (oxidizable) surface area are effective means of reducing depletion. Further, a portion of the depletion has been shown to be due to the presence of free C released by the dissociation of CH 4 . This depletion component can be reduced by reducing the helium residence time (increasing the helium flow rate) or by reducing the CH 4 concentration in the test gas. Equipment modifications to reduce depletion have been developed, tested, and in most cases implemented in the HTRMTL to date. These include increasing the Helium Loop No. 1 pumping capacity, conversion of metallic retorts and radiation shields to alumina, isolation of thermocouple probes from the test gas by alumina thermowells, and substitution of non-reactive Mo-TZM for reactive metallic structural components

  12. Wide-range vortex shedding flowmeter for high-temperature helium gas

    Baker, S.P.; Herndon, P.G.; Ennis, R.M. Jr.

    1983-01-01

    The existing design of a commercially available vortex shedding flowmeter (VSFM) was modified and optimized to produce three 4-in. and one 6-in. high-performance VSFMs for measuring helium flow in a gas-cooled fast reactor (GCFR) test loop. The project was undertaken because of the significant economic and performance advantages to be realized by using a single flowmeter capable of covering the 166:1 flow range (at 350/sup 0/C and 45:1 pressure range) of the tests. A detailed calibration in air and helium at the Colorado Engineering Experiment Station showed an accuracy of +-1% of reading for a 100:1 helium flow range and +-1.75% of reading for a 288:1 flow range in both helium and air. At an extended gas temperature of 450/sup 0/C, water cooling was necessary for reliable flowmeter operation.

  13. Effects of hydrogen mixture into helium gas on deuterium removal from lithium titanate

    Tsuchiya, Akihito, E-mail: tsuchiya@frontier.hokudai.ac.jp [Laboratory of Plasma Physics and Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Hino, Tomoaki; Yamauchi, Yuji; Nobuta, Yuji [Laboratory of Plasma Physics and Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Akiba, Masato; Enoeda, Mikio [Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193 (Japan)

    2013-10-15

    Lithium titanate (Li{sub 2}TiO{sub 3}) pebbles were irradiated with deuterium ions with energy of 1.7 keV and then exposed to helium or helium–hydrogen mixed gas at various temperatures, in order to evaluate the effects of gas exposure on deuterium removal from the pebbles. The amounts of residual deuterium in the pebbles were measured by thermal desorption spectroscopy. The mixing of hydrogen gas into helium gas enhanced the removal amount of deuterium. In other words, the amount of residual deuterium after the helium–hydrogen mixed gas exposure at lower temperature was lower than that after the helium gas exposure. In addition, we also evaluated the pebbles exposed to the helium gas with different hydrogen mixture ratio from 0% to 1%, at 573 K. Although the amount of residual deuterium in the pebbles after the exposure decreased with increasing the hydrogen mixture ratio, the implanted deuterium partly remained after the exposure. These results suggest that the tritium inventory may occur at low temperature region in the blanket during the operation.

  14. Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas

    Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

    2014-01-29

    In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

  15. Radiation and gas conduction heat transport across a helium dewer multilayer insulation system

    Green, M.A. [Lawrence Berkeley Lab., CA (United States)

    1995-02-01

    This report describes a method for calculating mixed heat transfer through the multilayer insulation used to insulated a 4K liquid helium cryostat. The method described permits one to estimate the insulation potential for a multilayer insulation system from first principles. The heat transfer regimes included are: radiation, conduction by free molecule gas conduction, and conduction through continuum gas conduction. Heat transfer in the transition region between the two gas conduction regimes is also included.

  16. Prospects of power conversion technology of direct-cycle helium gas turbine for MHTGR

    Li Yong; Zhang Zuoyi

    1999-01-01

    The modular high temperature gas cooled reactor (MHTGR) is a modern passively safe reactor. The reactor and helium gas turbine may be combined for high efficiency's power conversion, because MHTGR has high outlet temperature up to 950 degree C. Two different schemes are planed separately by USA and South Africa. the helium gas turbine methodologies adopted by them are mainly based on the developed heavy duty industrial and aviation gas turbine technology. The author introduces the differences of two technologies and some design issues in the design and manufacture. Moreover, the author conclude that directly coupling a closed Brayton cycle gas turbine concept to the passively safe MHTGR is the developing direction of MHTGR due to its efficiency which is much higher than that of using steam turbine

  17. Real-Gas Correction Factors for Hypersonic Flow Parameters in Helium

    Erickson, Wayne D.

    1960-01-01

    The real-gas hypersonic flow parameters for helium have been calculated for stagnation temperatures from 0 F to 600 F and stagnation pressures up to 6,000 pounds per square inch absolute. The results of these calculations are presented in the form of simple correction factors which must be applied to the tabulated ideal-gas parameters. It has been shown that the deviations from the ideal-gas law which exist at high pressures may cause a corresponding significant error in the hypersonic flow parameters when calculated as an ideal gas. For example the ratio of the free-stream static to stagnation pressure as calculated from the thermodynamic properties of helium for a stagnation temperature of 80 F and pressure of 4,000 pounds per square inch absolute was found to be approximately 13 percent greater than that determined from the ideal-gas tabulation with a specific heat ratio of 5/3.

  18. Optimization design of turbo-expander gas bearing for a 500W helium refrigerator

    Li, S. S.; Fu, B.; Y Zhang, Q.

    2017-12-01

    Turbo-expander is the core machinery of the helium refrigerator. Bearing as the supporting element is the core technology to impact the design of turbo-expander. The perfect design and performance study for the gas bearing are essential to ensure the stability of turbo-expander. In this paper, numerical simulation is used to analyze the performance of gas bearing for a 500W helium refrigerator turbine, and the optimization design of the gas bearing has been completed. And the results of the gas bearing optimization have a guiding role in the processing technology. Finally, the turbine experiments verify that the gas bearing has good performance, and ensure the stable operation of the turbine.

  19. 75 FR 75995 - Request for Comments on Helium-3 Use in the Oil and Natural Gas Well Logging Industry

    2010-12-07

    ... manufacture neutron detectors used by the well logging industry or wireline or Logging-While-Drilling tools... DEPARTMENT OF ENERGY Request for Comments on Helium-3 Use in the Oil and Natural Gas Well Logging... of Helium-3 by the oil and gas well logging industry. DATES: Written comments and information are...

  20. Behavior of W-based materials in hot helium gas

    Matějíček, Jiří; Vilémová, Monika; Hadraba, Hynek; Di Gabriele, F.; Kuběna, Ivo; Kolíbalová, E.; Michalička, J.; Čech, J.; Jäger, Aleš

    2016-01-01

    Roč. 9, December (2016), s. 405-410 ISSN 2352-1791. [International Conference of Fusion Reactor Material (ICFRM-17) /17./. Aachen, 11.10.2015-16.10.2015] R&D Projects: GA ČR(CZ) GA14-12837S Institutional support: RVO:61389021 ; RVO:68081723 ; RVO:68378271 Keywords : tungsten * helium * fusion materials Subject RIV: JG - Metallurgy; JG - Metallurgy (UFM-A); JG - Metallurgy (FZU-D) http://dx.doi.org/10.1016/j.nme.2016.03.009

  1. Experimental study on cryogenic adsorption of methane by activated carbon for helium coolant purification of High-Temperature Gas-cooled Reactor

    Chang, Hua; Wu, Zong-Xin; Jia, Hai-Jun

    2017-01-01

    Highlights: • The cryogenic CH 4 adsorption on activated carbon was studied for design of HTGR. • The breakthrough curves at different conditions were analyzed by the MTZ model. • The CH 4 adsorption isotherm was fitted well by the Toth model and the D-R model. • The work provides valuable reference data for helium coolant purification of HTGR. - Abstract: The cryogenic adsorption behavior of methane on activated carbon was investigated for helium coolant purification of high-temperature gas-cooled reactor by using dynamic column breakthrough method. With helium as carrier gas, experiments were performed at −196 °C and low methane partial pressure range of 0–120 Pa. The breakthrough curves at different superficial velocities and different feed concentrations were measured and analyzed by the mass-transfer zone model. The methane single-component adsorption isotherm was obtained and fitted well by the Toth model and the Dubinin-Radushkevich model. The adsorption heat of methane on activated carbon was estimated. The cryogenic adsorption process of methane on activated carbon has been verified to be effective for helium coolant purification of high-temperature gas-cooled reactor.

  2. Adsorption purification of helium coolant of high-temperature gas-cooled reactors of carbon dioxide

    Varezhkin, A.V.; Zel'venskij, Ya.D.; Metlik, I.V.; Khrulev, A.A.; Fedoseenkin, A.N.

    1986-01-01

    A series experiments on adsorption purification of helium of CO 2 using national adsorbent under the conditions characteristic of HTGR type reactors cleanup system is performed. The experimnts have been conducted under the dynamic mode with immobile adsorbent layer (CaA zeolite) at gas flow rates from 0,02 to 0,055 m/s in the pressure range from 0,8 to 5 MPa at the temperature of 273 and 293 K. It is shown that the adsorption grows with the decrease of gas rate, i.e. with increase of contact time with adsorbent. The helium pressure, growth noticeably whereas the temperature decrease from 293 to 273 K results in adsorption 2,6 times increase. The conclusion is drawn that it is advisable drying and purification of helium of CO 2 to perform separately using different zeolites: NaA - for water. CaA - for CO 2 . Estimations of purification unit parameters are realized

  3. Soil-gas radon/helium surveys in some neotectonic areas of NW Himalayan foothills, India

    S. Mahajan

    2010-06-01

    Full Text Available The present research is aimed at accessing the relationship between variation in the soil gases radon (222Rn and helium (4He and recently developed fissures and other neotectonic features in Nurpur and Nadha areas of the NW Himalayas, India. Two soil-gas surveys were conducted on/near known faults to reconfirm their position using soil gas technique and to check their present activity. During these surveys, soil-gas samples were collected along traverses crossing the observed structures. The data analysis reveals that the concentrations of radon and helium along the Dehar lineament and the longitudinal profile (Profile D are very high compared to any other thrust/lineament of the Nurpur area. The Nadha area shows high values of radon and helium concentrations along/near the Himalayan Frontal Fault (HFF as compared to the adjoining areas. This indicates the presence of some buried fault/fault zone running parallel to the HFF, not exposed to the surface and not delineated by satellite data but is geochemically active and might be tectonically active too. Hence, soil helium and radon gas patterns have been combined with morphological and geological observations to supply useful constraints for deformation of tectonic environments.

  4. Disruption mitigation with high-pressure helium gas injection on EAST tokamak

    Chen, D. L.; Shen, B.; Granetz, R. S.; Qian, J. P.; Zhuang, H. D.; Zeng, L.; Duan, Y.; Shi, T.; Wang, H.; Sun, Y.; Xiao, B. J.

    2018-03-01

    High pressure noble gas injection is a promising technique to mitigate the effect of disruptions in tokamaks. In this paper, results of mitigation experiments with low-Z massive gas injection (helium) on the EAST tokamak are reported. A fast valve has been developed and successfully implemented on EAST, with valve response time  ⩽150 μs, capable of injecting up to 7 × 1022 particles, corresponding to 300 times the plasma inventory. Different amounts of helium gas were injected into stable plasmas in the preliminary experiments. It is seen that a small amount of helium gas (N_He≃ N_plasma ) can not terminate a discharge, but can trigger MHD activity. Injection of 40 times the plasma inventory impurity (N_He≃ 40× N_plasma ) can effectively radiate away part of the thermal energy and make the electron density increase rapidly. The mitigation result is that the current quench time and vertical displacement can both be reduced significantly, without resulting in significantly higher loop voltage. This also reduces the risk of runaway electron generation. As the amount of injected impurity gas increases, the gas penetration time decreases slowly and asymptotes to (˜7 ms). In addition, the impurity gas jet has also been injected into VDEs, which are more challenging to mitigate that stable plasmas.

  5. Method of collecting helium cover gas for heavy water moderated reactor

    Miyamoto, Keiji; Ueda, Hiroshi.

    1981-01-01

    Purpose: To reduce the systematic facility cost in a heavy water moderated reactor by contriving the simplification of a helium cover gas collecting intake system. Method: A detachable low pressure metal tank and a neoprene balloon are prepared for a vacuum pump in a permanent vacuum drying facility. When all of the helium cover gas is collected from a heavy water moderated reactor, a large capacity of neoprene balloon capable of temporarily storing it under low pressure is connected to the exhaust of the vacuum pump. On the other hand, while the reactor is operating, a suitable amount of the low pressure tank or neoprene balloon is connected to the exhaust side of the pump, thereby regulating the pressure of the helium cover gas. When refeeding the cover gas, the balloon, with a large capacity for collecting and storing the cover gas is connected to the intake side of the pump. Thus, the pressure regulation, collection of all of the cover gas and refeeding of the cover gas can be conducted without using a high discharge pump and high pressure tank. (Kamimura, M.)

  6. Investigation of the helium proportion influence on the Prandtl number value of gas mixtures

    S. A. Burtsev

    2014-01-01

    Full Text Available The paper investigates an influence of helium fraction (light gases on the Prandtl number value for binary and more complex gas mixtures.It is shown that a low value of the Prandtl number (Pr-number results in decreasing a temperature recovery factor value and, respectively, in reducing a recovery temperature value on the wall (thermoinsulated wall temperature with the compressive gas flow bypassing it. This, in turn, allows us to increase efficiency of gasdynamic energy separation in Leontyev's tube.The paper conducts a numerical research of the influence of binary and more complex gas mixture composition on the Prandtl number value. It is shown that a mixture of two gases with small and large molecular weight allows us to produce a mixture with a lower value of the Prandtl number in comparison with the initial gases. Thus, the value of Prandtl number decreases by 1.5-3.2 times in comparison with values for pure components (the more a difference of molar mass of components, the stronger is a decrease.The technique to determine the Prandtl number value for mixtures of gases in the wide range of temperatures and pressure is developed. Its verification based on experimental data and results of numerical calculations of other authors is executed. It is shown that it allows correct calculation of binary and more complex mixtures of gasesFor the mixtures of inert gases it has been obtained that the minimum value of the Prandtl number is as follows: for helium - xenon mixtures (He-Xe makes 0.2-0.22, for helium - krypton mixtures (He-Kr – 0.3, for helium - argon mixes (He-Ar – 0.41.For helium mixture with carbon dioxide the minimum value of the Prandtl number makes about 0.4, for helium mixture with N2 nitrogen the minimum value of the Prandtl number is equal to 0.48, for helium-methane (CH4 - 0.5 and helium – oxygen (O2 – 0.46.This decrease is caused by the fact that the thermal capacity of mixture changes under the linear law in regard to the

  7. Influence of Carrier Gas Composition on the Stress of Al2O3 Coatings Prepared by the Aerosol Deposition Method

    Michael Schubert

    2014-08-01

    Full Text Available Al2O3 films were prepared by the aerosol deposition method at room temperature using different carrier gas compositions. The layers were deposited on alumina substrates and the film stress of the layer was calculated by measuring the deformation of the substrate. It was shown that the film stress can be halved by using oxygen instead of nitrogen or helium as the carrier gas. The substrates were annealed at different temperature steps to gain information about the temperature dependence of the reduction of the implemented stress. Total relaxation of the stress can already be achieved at 300 °C. The XRD pattern shows crystallite growth and reduction of microstrain while annealing.

  8. First principles study of inert-gas (helium, neon, and argon) interactions with hydrogen in tungsten

    Kong, Xiang-Shan [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Hou, Jie [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Li, Xiang-Yan [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Wu, Xuebang, E-mail: xbwu@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Liu, C.S., E-mail: csliu@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Chen, Jun-Ling; Luo, G.-N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2017-04-15

    We have systematically evaluated binding energies of hydrogen with inert-gas (helium, neon, and argon) defects, including interstitial clusters and vacancy-inert-gas complexes, and their stable configurations using first-principles calculations. Our calculations show that these inert-gas defects have large positive binding energies with hydrogen, 0.4–1.1 eV, 0.7–1.0 eV, and 0.6–0.8 eV for helium, neon, and argon, respectively. This indicates that these inert-gas defects can act as traps for hydrogen in tungsten, and impede or interrupt the diffusion of hydrogen in tungsten, which supports the discussion on the influence of inert-gas on hydrogen retention in recent experimental literature. The interaction between these inert-gas defects and hydrogen can be understood by the attractive interaction due to the distortion of the lattice structure induced by inert-gas defects, the intrinsic repulsive interaction between inert-gas atoms and hydrogen, and the hydrogen-hydrogen repelling in tungsten lattice.

  9. Atmospheric pressure helium afterglow discharge detector for gas chromatography

    Rice, Gary; D'Silva, Arthur P.; Fassel, Velmer A.

    1986-05-06

    An apparatus for providing a simple, low-frequency electrodeless discharge system for atmospheric pressure afterglow generation. A single quartz tube through which a gas mixture is passed is extended beyond a concentric electrode positioned thereabout. A grounding rod is placed directly above the tube outlet to permit optical viewing of the discharge between the electrodes.

  10. Results of the gas carrier reliquefaction plant trial

    Y. Fatyhov

    2007-12-01

    Full Text Available In the paper results of the gas carrier reliquefaction plant trial are considered. Safe transportation of liquefied gases is explained. The construction of the ship on trial is described. Designed parameters of the reliquefaction plant are presented. Heat gain into cargo tanks is obtained. Volumetric capacity, cooling capacity, volumetric efficiency and power consumption of the compressors are determined. Results of the main engine trial, diesel generator trial, reliquefaction plant trial, and calculations performed after wards are represented in five tables. The results obtained may be used for optimisation calculations of gas carriers’ reliquefaction plants.

  11. 46 CFR 111.105-32 - Bulk liquefied flammable gas and ammonia carriers.

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Bulk liquefied flammable gas and ammonia carriers. 111... gas and ammonia carriers. (a) Each vessel that carries bulk liquefied flammable gases or ammonia as a.... (2) The term “gas-dangerous” does not include the weather deck of an ammonia carrier. (c) Each...

  12. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    Pinchuk, M; Kurakina, N; Spodobin, V; Stepanova, O

    2017-01-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow. (paper)

  13. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    Pinchuk, M.; Stepanova, O.; Kurakina, N.; Spodobin, V.

    2017-05-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow.

  14. High-Temperature Structural Analysis Model of the Process Heat Exchanger for Helium Gas Loop (II)

    Song, Kee Nam; Lee, Heong Yeon; Kim, Chan Soo; Hong, Seong Duk; Park, Hong Yoon

    2010-01-01

    PHE (Process Heat Exchanger) is a key component required to transfer heat energy of 950 .deg. C generated in a VHTR (Very High Temperature Reactor) to the chemical reaction that yields a large quantity of hydrogen. Korea Atomic Energy Research Institute established the helium gas loop for the performance test of components, which are used in the VHTR, and they manufactured a PHE prototype to be tested in the loop. In this study, as part of the high temperature structural-integrity evaluation of the PHE prototype, which is scheduled to be tested in the helium gas loop, we carried out high-temperature structural-analysis modeling, thermal analysis, and thermal expansion analysis of the PHE prototype. The results obtained in this study will be used to design the performance test setup for the PHE prototype

  15. Population inversion in a recombining hydrogen plasma interacting with a helium gas

    Oda, Toshiatsu; Furukane, Utaro.

    1984-08-01

    A numerical investigation has shown that the population inversion between the levels with the principal quantum number i=2 and 3 takes place in a recombining hydrogen plasma which is interacting with a cool and dense helium gas on the basis of a collisional- radiative (CR) model. Overpopulation density Δn 32 , which is defined as the difference between the population densities per unit statistical weight of the upper and lower excited levels 3 and 2, is found to be much higher than a threshold level for the laser oscillation in the quasi-steady state when the hydrogen plasma with nsub(e) = 10 13 --10 14 cm -3 interacts with the helium gas with pressure of --50 Torr. (author)

  16. Theoretical and experimental studies on transient forced convection heat transfer of helium gas

    Liu, Qiusheng; Fukuda, Katsuya; Shibahara, Makoto

    2008-01-01

    Forced convection transient heat transfer for helium gas at various periods of exponential increase of heat input to a horizontal cylinder and a plate (ribbon) one was experimentally and theoretically studied. In the experimental studies, the authors measured heat flux, surface temperature, and transient heat transfer coefficients for forced convection flow of helium gas over a horizontal cylinder and a plate (ribbon) one under wide experimental conditions. Empirical correlations for quasi-steady-state heat transfer and transient heat transfer were obtained based on the experimental data. In the theoretical study, transient heat transfer was numerically solved based on a turbulent flow model. The values of numerical solution for surface temperature and heat flux were compared and discussed with authors' experimental data. (author)

  17. Pulse Shape Analysis and Discrimination for Silicon-Photomultipliers in Helium-4 Gas Scintillation Neutron Detector

    Barker, Cathleen; Zhu, Ting; Rolison, Lucas; Kiff, Scott; Jordan, Kelly; Enqvist, Andreas

    2018-01-01

    Using natural helium (helium-4), the Arktis 180-bar pressurized gas scintillator is capable of detecting and distinguishing fast neutrons and gammas. The detector has a unique design of three optically separated segments in which 12 silicon-photomultiplier (SiPM) pairs are positioned equilaterally across the detector to allow for them to be fully immersed in the helium-4 gas volume; consequently, no additional optical interfaces are necessary. The SiPM signals were amplified, shaped, and readout by an analog board; a 250 MHz, 14-bit digitizer was used to examine the output pulses from each SiPMpair channel. The SiPM over-voltage had to be adjusted in order to reduce pulse clipping and negative overshoot, which was observed for events with high scintillation production. Pulse shaped discrimination (PSD) was conducted by evaluating three different parameters: time over threshold (TOT), pulse amplitude, and pulse integral. In order to differentiate high and low energy events, a 30ns gate window was implemented to group pulses from two SiPM channels or more for the calculation of TOT. It was demonstrated that pulses from a single SiPM channel within the 30ns window corresponded to low-energy gamma events while groups of pulses from two-channels or more were most likely neutron events. Due to gamma pulses having lower pulse amplitude, the percentage of measured gamma also depends on the threshold value in TOT calculations. Similarly, the threshold values were varied for the optimal PSD methods of using pulse amplitude and pulse area parameters. Helium-4 detectors equipped with SiPMs are excellent for in-the-field radiation measurement of nuclear spent fuel casks. With optimized PSD methods, the goal of developing a fuel cask content monitoring and inspection system based on these helium-4 detectors will be achieved.

  18. A helium gas scintillator active target for photoreaction measurements

    Al Jebali, Ramsey; Annand, John R.M.; Buchanan, Emma; Gardner, Simon; Hamilton, David J.; Livingston, Kenneth; McGeorge, John C.; MacGregor, Ian J.D.; MacRae, Roderick; Reiter, Andreas J.H.; Rosner, Guenther; Sokhan, Daria; Strandberg, Bruno [University of Glasgow, School of Physics and Astronomy, Glasgow, Scotland (United Kingdom); Adler, Jan-Olof; Fissum, Kevin; Schroeder, Bent [University of Lund, Department of Physics, Lund (Sweden); Akkurt, Iskender [Sueleyman Demirel University, Fen-Edebiyat Faculty, Isparta (Turkey); Brudvik, Jason; Hansen, Kurt; Isaksson, Lennart; Lundin, Magnus [MAX IV Laboratory, PO Box 118, Lund (Sweden); Middleton, Duncan G. [Universitaet Tuebingen, Kepler Centre for Astro and Particle Physics, Physikalisches Institut, Tuebingen (Germany); Sjoegren, Johan [University of Glasgow, School of Physics and Astronomy, Glasgow, Scotland (United Kingdom); MAX IV Laboratory, PO Box 118, Lund (Sweden)

    2015-10-15

    A multi-cell He gas scintillator active target, designed for the measurement of photoreaction cross sections, is described. The target has four main chambers, giving an overall thickness of 0.103 g/cm{sup 3} at an operating pressure of 2 MPa. Scintillations are read out by photomultiplier tubes and the addition of small amounts of N{sub 2} to the He, to shift the scintillation emission from UV to visible, is discussed. First results of measurements at the MAX IV Laboratory tagged-photon facility show that the target has a timing resolution of around 1 ns and can cope well with a high-flux photon beam. The determination of reaction cross sections from target yields relies on a Monte Carlo simulation, which considers scintillation light transport, photodisintegration processes in {sup 4}He, background photon interactions in target windows and interactions of the reaction-product particles in the gas and target container. The predictions of this simulation are compared to the measured target response. (orig.)

  19. Effects of cyclic mean pressure of helium gas on performance of integral crank driven stirling cryocooler

    Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je [Korea Institute of Machinery and Materials, Changwon (Korea, Republic of)

    2016-09-15

    An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space.

  20. Effects of cyclic mean pressure of helium gas on performance of integral crank driven stirling cryocooler

    Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je

    2016-01-01

    An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space

  1. Observations of a fcc helium gas-bubble superlattice in copper, nickel, and stainless steel

    Johnson, P.B.; Mazey, D.J.

    1980-01-01

    Transmission electron microscopy is used to investigate the spatial arrangement of the small gas bubbles produced in several fcc metals by 30 keV helium ion irradiation to high dose at 300 K. In what is a new result for this important class of metals it is found that the helium gas bubbles lie on a superlattice having an fcc structure with principal axes aligned with those of the metal matrix. The bubble lattice constant asub(i), is measured for a helium fluence just below the critical dose for radiation blistering of the metal surface (approximately 4 x 10 17 He/cm 2 ). Implantation rates are typically approximately 10 14 He ions cm -2 sec -1 . The values of asub(i) obtained for copper, nickel and stainless steel are (7.6 +- 0.3)nm, (6.6 +- 0.5)nm and (6.4 +- 0.5)nm respectively. Above the critical dose the bubble lattice is seen to survive in some blister caps as well as in the region between blisters. Bubble alignment is also observed in the case of hydrogen bubbles produced in copper by low energy proton irradiation to high fluence at 300 K. The presentation of this data was accompanied by a cine film illustrating the behaviour of the gas bubble lattice in copper during post-irradiation annealing in the electron microscope. A summary of the film is given in the appendix. (author)

  2. Presentation summary: Gas Turbine - Modular Helium Reactor (GT-MHR)

    2001-01-01

    Numerous prototypes and demonstration plants have been constructed and operated beginning with the Dragon plant in the early 1960s. The MHTGR was the U.S. developed modular plant and underwent pre application review by NRC. The GT-MHR represents a further refinement on this concept with the steam cycle being replaced by a closed loop gas turbine (Brayton) cycle. Modular gas reactors and the GT-MHR represent a fundamental shift in reactor design and safety philosophy. The reactor system is contained in a 3 vessel, side-by-side arrangement. The reactor and a shutdown cooling system are in one vessel, and the gas turbine based power conversion system, including the generator, in a second parallel vessel. A more detailed look at the system shows the compact arrangement of gas turbine, compressors, recuperator, heat exchanges, and generator. Fueled blocks are stacked in three concentric rings with inert graphite blocks making up the inner and outer reflectors. Operating control rods are located outside the active core while startup control rods and channels for reserve shutdown pellets are located near the core center. Ceramic coated fuel is the key to the GT-MHR's safety and economics. A kernel of Uranium oxycarbide (or UO 2 ) is placed in a porous carbon buffer and then encapsulated in multiple layers of pyrolytic carbon and silicon carbide. These micro pressure vessels withstand internal pressures of up to 2,000 psi and temperatures of nearly 2,000 C providing extremely resilient containment of fission products under both normal operating and accident conditions. The fuel particles are blended in carbon pitch, forming fuel rods, and then loaded into holes within large graphite fuel elements. Fuel elements are stacked to form the core. Fuel particle testing in has repeatedly demonstrated the high temperature resilience of coated particle fuel to temperature approaching 2,000 C. As an conservative design goal, GT-MHR has been sized to keep maximum fuel temperatures

  3. Operating experience of gas bearing helium circulators in HTGR development facility

    Shimomura, H.; Kawaji, S.; Fujisaki, K.; Ihizuka, T.

    1988-01-01

    The large scale helium gas test facility (HENDEL) has been constructed and operated since March 1982 at the Japan Atomic Energy Research Institute to develop HTGR components. The five electric driven gas circulators with dynamic gas bearings are used to circulate the helium gas of 4MPa and 400 deg. C in loops for their compactness, gas tightness, easy maintenance and free from gas contamination. All of these circulators are variable speed types of 3,000 to 12,000 rpm and have the same gas bearings and electric motors. The four machines among them are equipped with centrifugal impeller and one other machine has regenerative type, and the weight of both type rotors are nearly the same. After the troubles and repairing, both type of circulators were tested and the vibration characteristics were measured as preventing maintenance. From the test and measurements of the circulators, it was presumed that the first trouble on regenerative type was caused from excess unbalance force by falling off of a small pin from the rotating part and the second severe trouble on it was caused by the whipping in gas bearing. The static load on tilting pads indicated close relations to occurrence of the whirling through the measurements. It is recognized that fine balancing of the rotors and delicate clearance adjustment of the bearings are very important for the rotor stability and that the mechanism should be designed and machined so precise as to be adjustable. As the gas bearing would be damaged in an instantaneously short time, the monitoring technique for it should be so fast and predictive as to prevent serious damage. Through the tests, the vibration spectrum monitoring method seems to be predictive and useful for early detection of the shaft instability. It will be concluded that the gas bearing machine is an excellent system in its design philosophy, however, it also needs highly precise machining and delicate maintenance technique. 4 refs, 10 figs, 1 tab

  4. Polarizability of Helium, Neon, and Argon: New Perspectives for Gas Metrology

    Gaiser, Christof; Fellmuth, Bernd

    2018-03-01

    With dielectric-constant gas thermometry, the molar polarizability of helium, neon, and argon has been determined with relative standard uncertainties of about 2 parts per million. A series of isotherms measured with the three noble gases and two different experimental setups led to this unprecedented level of uncertainty. These data are crucial for scientists in the field of gas metrology, working on pressure and temperature standards. Furthermore, with the new benchmark values for neon and argon, theoretical calculations, today about 3 orders of magnitude larger in uncertainty, can be checked and improved.

  5. First Study of Helium Gas Purification System as Primary Coolant of Co-Generation Reactor

    Piping Supriatna

    2009-01-01

    The technological progress of NPP Generation-I on 1950’s, Generation-II, Generation-III recently on going, and Generation-IV which will be implemented on next year 2025, concept of nuclear power technology implementation not only for generate electrical energy, but also for other application which called cogeneration reactor. Commonly the type of this reactor is High Temperature Reactor (HTR), which have other capabilities like Hydrogen production, desalination, Enhanced Oil Recovery (EOR), etc. The cogeneration reactor (HTR) produce thermal output higher than commonly Nuclear Power Plant, and need special Heat Exchanger with helium gas as coolant. In order to preserve heat transfer with high efficiency, constant purity of the gas must be maintained as well as possible, especially contamination from its impurities. In this report has been done study for design concept of HTR primary coolant gas purification system, including methodology by sampling He gas from Primary Coolant and purification by using Physical Helium Splitting Membrane. The examination has been designed in physical simulator by using heater as reactor core. The result of study show that the of Primary Coolant Gas Purification System is enable to be implemented on cogeneration reactor. (author)

  6. Test results from a helium gas-cooled porous metal heat exchanger

    North, M.T.; Rosenfeld, J.H.; Youchison, D.L.

    1996-01-01

    A helium-cooled porous metal heat exchanger was built and tested, which successfully absorbed heat fluxes exceeding all previously tested gas-cooled designs. Helium-cooled plasma-facing components are being evaluated for fusion applications. Helium is a favorable coolant for fusion devices because it is not a plasma contaminant, it is not easily activated, and it is easily removed from the device in the event of a leak. The main drawback of gas coolants is their relatively poor thermal transport properties. This limitation can be removed through use of a highly efficient heat exchanger design. A low flow resistance porous metal heat exchanger design was developed, based on the requirements for the Faraday shield for the International Thermonuclear Experimental Reactor (ITER) device. High heat flux tests were conducted on two representative test articles at the Plasma Materials Test Facility (PMTF) at Sandia National Laboratories. Absorbed heat fluxes as high as 40 MW/m 2 were successfully removed during these tests without failure of the devices. Commercial applications for electronics cooling and other high heat flux applications are being identified

  7. The observation of helium gas bubble lattices in copper, nickel and stainless steel

    Johnson, P.B.; Mazey, D.J.

    1978-10-01

    Transmission electron microscopy is used to investigate the spatial arrangement of the small gas bubbles produced in several fcc metals by 30 keV helium ion irradiation to high dose at 300K. In what is a new result for this important class of metals it is found that the helium gas bubbles lie on a superlattice having an fcc structure with principal axes aligned with those of the metal matrix. The bubble lattice constant, asub(l), is measured for a helium fluence just below the critical dose for radiation blistering of the metal surface. Implantation rates are typically approximately 10 14 He ions cm -2 sec -1 . The values of asub(l) obtained for copper, nickel and stainless steel are given. Above the critical dose the bubble lattice is seen to survive in some blister caps as well as in the region between blisters. Bubble alignment is also observed in the case of hydrogen bubbles produced in copper by low energy proton irradiation to high fluence at 300K. (author)

  8. The effect on the transmission loss of a double wall panel of using helium gas in the gap

    Atwal, M. S.; Crocker, M. J.

    The possibility of increasing the sound-power transmission loss of a double panel by using helium gas in the gap is investigated. The transmission loss of a panel is defined as ten times the common logarithm of the ratio of the sound power incident on the panel to the sound power transmitted to the space on the other side of the panel. The work is associated with extensive research being done to develop new techniques for predicting the interior noise levels on board high-speed advanced turboprop aircraft and reducing the noise levels with a minimum weight penalty. Helium gas was chosen for its inert properties and its low impedance compared with air. With helium in the gap, the impedance mismatch experienced by the sound wave will be greater than that with air in the gap. It is seen that helium gas in the gap increases the transmission loss of the double panel over a wide range of frequencies.

  9. Average equilibrium charge state of 278113 ions moving in a helium gas

    Kaji, D.; Morita, K.; Morimoto, K.

    2005-01-01

    Difficulty to identify a new heavy element comes from the small production cross section. For example, the production cross section was about 0.5 pb in the case of searching for the 112th element produced by the cold fusion reaction of 208 Pb( 70 Zn,n) 277 ll2. In order to identify heavier elements than element 112, the experimental apparatus with a sensitivity of sub-pico barn level is essentially needed. A gas-filled recoil separator, in general, has a large collection efficiency compared with other recoil separators as seen from the operation principle of a gas-filled recoil separator. One of the most important parameters for a gas-filled recoil separator is the average equilibrium charge state q ave of ions moving in a used gas. This is because the recoil ion can not be properly transported to the focal plane of the separator, if the q ave of an element of interest in a gas is unknown. We have systematically measured equilibrium charge state distributions of heavy ions ( 169 Tm, 208 Pb, 193,209 Bi, 196 Po, 200 At, 203,204 Fr, 212 Ac, 234 Bk, 245 Fm, 254 No, 255 Lr, and 265 Hs) moving in a helium gas by using the gas-filled recoil separator GARIS at RIKEN. Ana then, the empirical formula on q ave of heavy ions in a helium gas was derived as a function of the velocity and the atomic number of an ion on the basis of the Tomas-Fermi model of the atom. The formula was found to be applicable to search for transactinide nuclides of 271 Ds, 272 Rg, and 277 112 produced by cold fusion reactions. Using the formula on q ave , we searched for a new isotope of element 113 produced by the cold fusion reaction of 209 Bi( 70 Zn,n) 278 113. As a result, a decay chain due to an evaporation residue of 278 113 was observed. Recently, we have successfully observed the 2nd decay chain due to an evaporation residue of 278 113. In this report, we will present experimental results in detail, and will also discuss the average equilibrium charge sate of 278 113 in a helium gas by

  10. Reduction of circulation power for helium-cooled fusion reactor blanket using additive CO{sub 2} gas

    Lee, Yeon-Gun [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Department of Nuclear and Energy Engineering, Jeju National University, 102 Jejudaehakno, Jeju-si 690-756, Jeju (Korea, Republic of); Park, Il-Woong [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Lee, Dong Won [Nuclear Fusion Engineering Development Center, Korea Atomic Energy Research Institute, Daedeokdaero 989 beon-gil, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Park, Goon-Cherl [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Kim, Eung-Soo, E-mail: kes7741@snu.ac.kr [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

    2015-11-15

    Helium (He) cooling requires large circulation power to remove high heat from plasma side and nuclear heating by high energy neutron in fusion reactors due to its low density. Based on the recent findings that the heat transfer capability of the light gas can be enhanced by mixing another heavier gas, this study adds CO{sub 2} to a reference helium coolant and evaluates the cooling performance of the binary mixture for various compositions. To assess the cooling performance, computational fluid dynamic (CFD) analyses on the KO HCML (Korea Helium Cooled Molten Lithium) TBM are conducted. As a result, it is revealed that the binary mixing of helium, which has favorable thermophysical properties but the density, with a heavier noble gas or an unreactive gas significantly reduces the required circulation power by an order of magnitude with meeting the thermal design requirements. This is attributed to the fact that the density can be highly increased with small amount of a heavier gas while other gas properties are kept relatively comparable. The optimal CO{sub 2} mole fraction is estimated to be 0.4 and the circulation power, in this case, can be reduced to 13% of that of pure helium. This implies that the thermal efficiency of a He-cooled blanket system can be fairly enhanced by means of the proposed binary mixing.

  11. Multiple scattering effects in fast neutron polarization experiments using high-pressure helium-xenon gas scintillators as analyzers

    Tornow, W.; Mertens, G.

    1977-01-01

    In order to study multiple scattering effects both in the gas and particularly in the solid materials of high-pressure gas scintillators, two asymmetry experiments have been performed by scattering of 15.6 MeV polarized neutrons from helium contained in stainless steel vessels of different wall thicknesses. A monte Carlo computer code taking into account the polarization dependence of the differential scattering cross sections has been written to simulate the experiments and to calculate corrections for multiple scattering on helium, xenon and the gas containment materials. Besides the asymmetries for the various scattering processes involved, the code yields time-of-flight spectra of the scattered neutrons and pulse height spectra of the helium recoil nuclei in the gas scintillator. The agreement between experimental results and Monte Carlo calculations is satisfactory. (Auth.)

  12. Thermophysical properties of krypton-helium gas mixtures from ab initio pair potentials.

    Jäger, Benjamin; Bich, Eckard

    2017-06-07

    A new potential energy curve for the krypton-helium atom pair was developed using supermolecular ab initio computations for 34 interatomic distances. Values for the interaction energies at the complete basis set limit were obtained from calculations with the coupled-cluster method with single, double, and perturbative triple excitations and correlation consistent basis sets up to sextuple-zeta quality augmented with mid-bond functions. Higher-order coupled-cluster excitations up to the full quadruple level were accounted for in a scheme of successive correction terms. Core-core and core-valence correlation effects were included. Relativistic corrections were considered not only at the scalar relativistic level but also using full four-component Dirac-Coulomb and Dirac-Coulomb-Gaunt calculations. The fitted analytical pair potential function is characterized by a well depth of 31.42 K with an estimated standard uncertainty of 0.08 K. Statistical thermodynamics was applied to compute the krypton-helium cross second virial coefficients. The results show a very good agreement with the best experimental data. Kinetic theory calculations based on classical and quantum-mechanical approaches for the underlying collision dynamics were utilized to compute the transport properties of krypton-helium mixtures in the dilute-gas limit for a large temperature range. The results were analyzed with respect to the orders of approximation of kinetic theory and compared with experimental data. Especially the data for the binary diffusion coefficient confirm the predictive quality of the new potential. Furthermore, inconsistencies between two empirical pair potential functions for the krypton-helium system from the literature could be resolved.

  13. A Gas Chromatographic System for the Detection of Ethylene Gas Using Ambient Air as a Carrier Gas.

    Zaidi, Nayyer Abbas; Tahir, Muhammad Waseem; Vellekoop, Michael J; Lang, Walter

    2017-10-07

    Ethylene gas is a naturally occurring gas that has an influence on the shelf life of fruit during their transportation in cargo ships. An unintentional exposure of ethylene gas during transportation results in a loss of fruit. A gas chromatographic system is presented here for the detection of ethylene gas. The gas chromatographic system was assembled using a preconcentrator, a printed 3D printed gas chromatographic column, a humidity sensor, solenoid valves, and an electrochemical ethylene gas sensor. Ambient air was used as a carrier gas in the gas chromatographic system. The flow rate was fixed to 10 sccm. It was generated through a mini-pump connected in series with a mass flow controller. The metal oxide gas sensor is discussed with its limitation in ambient air. The results show the chromatogram obtained from metal oxide gas sensor has low stability, drifts, and has uncertain peaks, while the chromatogram from the electrochemical sensor is stable and precise. Furthermore, ethylene gas measurements at higher ppb concentration and at lower ppb concentration were demonstrated with the electrochemical ethylene gas sensor. The system separates ethylene gas and humidity. The chromatograms obtained from the system are stable, and the results are 1.2% repeatable in five similar measurements. The statistical calculation of the gas chromatographic system shows that a concentration of 2.3 ppb of ethylene gas can be detected through this system.

  14. Analysis of a gas absorption system with soluble carrier gas and volatile solvent

    Kanak, B.E.

    1980-01-01

    The effects of column diameter, carrier gas coabsorption, and solvent vaporization on the performance of a packed gas absorption column are examined. The system investigated employs dichlorodifluoromethane as a solvent to remove krypton from a nitrogen stream and is characterized by substantial nitrogen coabsorption. Three columns with diameters of 2, 3, and 4 inches were constructed and packed with 34.5 inches of Goodloe packing. In addition to the more conventional data, the experimental evaluation of these columns included the use of a radioisotope and a gamma scanning technique which provided direct measurement of the columns' molar krypton profiles. A multicomponent gas absorption model was developed, based on the two-film mass transfer theory, that allows the fluxes of all species to interact. Verification of this model was achieved through comparison of the calculated results with experimental data. With the feed gas flow rate between 6 and 36 lb moles/hr-ft 2 and the solvent feed rate between 40 and 400 lb moles/hr-ft 2 , column diameter was found to have no significant impact on the mass transfer efficiency of this system when carried out in columns with diameters of 2 inches or greater. The absorption of krypton was found to be enhanced and inhibited, respectively, by carrier gas coabsorption and solvent vaporization. An injector system to add gaseous solvent to the feed gas stream prior to its introduction into the packed bed was proposed to eliminate the detrimental effects of solvent vaporization.Using this injector to supersaturate the feed gas stream with solvent enhanced absorber performance in the same manner as carrier gas coabsorption

  15. Thermal performance test of hot gas ducts of helium engineering demonstration loop (HENDEL)

    Hishida, Makoto; Kunitomi, Kazuhiko; Ioka, Ikuo; Umenishi, Koji; Kondo, Yasuo; Tanaka, Toshiyuki; Shimomura, Hiroaki

    1984-01-01

    A hot gas duct provided with internal thermal insulation is supposed to be used for an experimental very high-temperature gas-cooled reactor (VHTR) which has been developed by the Japan Atomic Energy Research Institute (JAERI). This type of hot gas duct has not been used so far in industrial facilities, and only a couple of tests on such a large-scale model of hot gas duct have been conducted. The present test was to investigate the thermal performance of the hot gas ducts which are installed as parts of a helium engineering demonstration loop (HENDEL) of JAERI. Uniform temperature and heat flux distributions at the surface of the duct were observed, the experimental correlation being obtained for the effective thermal conductivity of the internal thermal insulation layer. The measured temperature distribution of the pressure tube was in good agreement with the calculation by a TRUMP heat transfer computer code. The temperature distribution of the inner tube of VHTR hot gas duct was evaluated, and no hot spot was detected. These results would be very valuable for the design and development of VHTR. (author)

  16. Advanced In-Core Fuel Cycles for the Gas Turbine-Modular Helium Reactor

    Talamo, Alberto

    2006-04-15

    Amid generation IV of nuclear power plants, the Gas Turbine - Modular Helium Reactor, designed by General Atomics, is the only core with an energy conversion efficiency of 50%; the safety aspects, coupled to construction and operation costs lower than ordinary Light Water Reactors, renders the Gas Turbine - Modular Helium reactor rather unequaled. In the present studies we investigated the possibility to operate the GT-MHR with two types of fuels: LWRs waste and thorium; since thorium is made of only fertile {sup 232}Th, we tried to mix it with pure {sup 233}U, {sup 235}U or {sup 239}Pu; ex post facto, only uranium isotopes allow the reactor operation, that induced us to examine the possibility to use a mixture of uranium, enriched 20% in {sup 235}U, and thorium. We performed all calculations by the MCNP and MCB codes, which allowed to model the reactor in a very detailed three-dimensional geometry and to describe the nuclides transmutation in a continuous energy approach; finally, we completed our studies by verifying the influence of the major nuclear data libraries, JEFF, JENDL and ENDF/B, on the obtained results.

  17. Hot corrosion behavior of Ni-Cr-W-C alloys in impure helium gas

    Ohmura, Taizo; Sahira, Kensho; Sakonooka, Akihiko; Yonezawa, Noboru

    1976-01-01

    Influence of the minor alloy constituents such as Al, Mn and Si on the hot corrosion behavior of Ni-20Cr-20W-0.07C alloy was studied in 99.995% helium gas at 1000 0 C, comparing with that behavior of commercial Ni-base superalloys (Hastelloy X and Inconel 617). The low oxidizing potential in the impure helium gas usually causes selective oxidation of these elements and the growth of oxide whiskers on the surface of specimen at elevated temperature. The intergranular attack was caused by selective oxidation of Al, Si and Mn. The spalling of oxide film was restrained by addition of Mn and Si, providing tough spinel type oxide film on the surface and 'Keyes' on the oxide-matrix interface respectively. The amount and the morphology of the oxide whiskers depended on Si and Mn content. More than 0.29% of Si content without Mn always caused the growth of rather thinner whiskers with smooth surface, and the whiskers analyzed by electron diffraction patterns and EPMA to be Cr 2 O 3 containing Si. Mn addition changed the whiskers to thicker ones of spinel type oxide (MnCr 2 O 1 ) with rough surface. On the basis of these results, the optimum content of Al, Mn and Si to minimize the growth of whiskers, the intergranular attack and the spalling of oxide film was discussed. (auth.)

  18. An advanced conceptual Tokamak fusion power reactor utilizing closed cycle helium gas turbines

    Conn, R.W.

    1976-01-01

    UWMAK-III is a conceptual Tokamak reactor designed to study the potential and the problems associated with an advanced version of Tokamaks as power reactors. Design choices have been made which represent reasonable extrapolations of present technology. The major features are the noncircular plasma cross section, the use of TZM, a molybdenum based alloy, as the primary structural material, and the incorporation of a closed-cycle helium gas turbine power conversion system. A conceptual design of the turbomachinery is given together with a preliminary heat exchanger analysis that results in relatively compact designs for the generator, precooler, and intercooler. This paper contains a general description of the UWMAK-III system and a discussion of those aspects of the reactor, such as the burn cycle, the blanket design and the heat transfer analysis, which are required to form the basis for discussing the power conversion system. The authors concentrate on the power conversion system and include a parametric performance analysis, an interface and trade-off study and a description of the reference conceptual design of the closed-cycle helium gas turbine power conversion system. (Auth.)

  19. Gas Breakdown of Radio Frequency Glow Discharges in Helium at near Atmospheric Pressure

    Liu Xinkun; Xu Jinzhou; Cui Tongfei; Guo Ying; Zhang Jing; Shi Jianjun

    2013-01-01

    A one-dimensional self-consistent fluid model was developed for radio frequency glow discharge in helium at near atmospheric pressure, and was employed to study the gas breakdown characteristics in terms of breakdown voltage. The effective secondary electron emission coefficient and the effective electric field for ions were demonstrated to be important for determining the breakdown voltage of radio frequency glow discharge at near atmospheric pressure. The constant of A was estimated to be 64±4 cm −1 Torr −1 , which was proportional to the first Townsend coefficient and could be employed to evaluate the gas breakdown voltage. The reduction in the breakdown voltage of radio frequency glow discharge with excitation frequency was studied and attributed to the electron trapping effect in the discharge gap

  20. Development of a wide range vortex shedding flowmeter for high temperature helium gas

    Baker, S.P.; Ennis, R.M. Jr.; Herndon, P.G.

    1981-07-01

    A flowmeter was required to measure recirculating helium gas flow over a wide range of conditions in a gas-cooled fast reactor (GCFR) core flow simulator, the ORNL Core Flow Test Loop (CFTL). The flow measurement requirements of the CFTL exceeded the proven performance of any single conventional flowmeter. Therefore, a special purpose vortex shedding flowmeter (VSFM) was developed. A single flowmeter capable of meeting all the CFTL requirements would provide significant economic and performance advantages in the operation of the loop. The development, conceptual design, and final design of a modified VSFM are described. The results of extensive flow calibration of the flowmeter at the Colorado Engineering Experiment Station (CEES) are presented. The report closes with recommendations for application of the VSFM to the CFTL and for future development work.

  1. Henry's law and accumulation of weak source for crust-derived helium: A case study of Weihe Basin, China

    Yuhong Li

    2017-12-01

    Full Text Available Crust-derived helium is generated from the radioactive decay of uranium, thorium and other radioactive elements in geological bodies. Compared with conventional natural gas, helium is a typical weak source gas as a result of extremely slow generation rate and absence of helium-generating peak. It is associated with methane or carbon dioxide reservoirs frequently and related to groundwater closely. Helium can meet the industry standard with 0.1% in volume fraction. In order to study the accumulation mechanism of helium, the previous research on Henry's coefficient and solubility of helium, nitrogen and methane are summarized and the key roles of Henry's Law in the helium migration, accumulation and preservation are discussed by simulating calculation taking Weihe Basin as an example. According to the Law, the gas solubility in dilute solution is controlled by the gas partial pressure and the Henry's coefficient. Compared with the carrier gases, the Henry's constant of helium is high, with striking difference at low and high temperature. In addition, the helium partial pressure is greatly different in helium source rocks and gas reservoirs, resulting in the great differences of helium solubility in the two places. The accumulation progresses are as follows. Firstly, helium can dissolve into water and migrate out of helium source rocks due to the high helium solubility, which is caused by high helium partial pressure and high temperature in source rock. Secondly, when dissolved helium is transported to the shallow gas reservoir, it is prone to be out of solution and into reservoir due to the extremely low partial pressure and low temperature. Meanwhile part of carrier gases dissolves into water, as if helium is “replaced” out. Furthermore, the low concentration funnel of dissolved helium is formed near the gas reservoir, then other dissolved helium continues to migrate towards the gas reservoir, which greatly improves the helium accumulation

  2. Desublimation of krypton from a noncondensable carrier gas

    Eby, R.S.

    1978-09-01

    A study was conducted to obtain column concentration profiles and point buildup rates for a cold trap freezing out krypton from a nitrogen carrier gas stream and to compare those experimentally obtained profiles with profiles generated from a theoretical model. Profiles were obtained over a range of flow conditions from 0.14 to 1.06 standard cubic feet per minute, krypton feed gas concentrations varied from 5.2 to 13.5%, and cold trap operating temperatures from -281 to -312 0 F. Gamma scintillation techniques using tracer amounts of krypton-85 provided the major analytical tool employed in the investigation. Data obtained from the experiments indicate that if values for the density and thermal conductivity of the krypton frost are known, the model can accurately predict krypton loading profiles in the cold trap. The frost density and frost conductivity appear to be functions of the freeze-out temperature and condensable krypton concentration. A discussion of cold trapping theory, a description of the experimental apparatus and tests performed, and an explanation of the usefulness of the model as a design tool for engineering use are included

  3. Carrier gas effects on aluminum-catalyzed nanowire growth

    Ke, Yue; Hainey, Mel Jr; Won, Dongjin; Weng, Xiaojun; Eichfeld, Sarah M; Redwing, Joan M

    2016-01-01

    Aluminum-catalyzed silicon nanowire growth under low-pressure chemical vapor deposition conditions requires higher reactor pressures than gold-catalyzed growth, but the reasons for this difference are not well understood. In this study, the effects of reactor pressure and hydrogen partial pressure on silicon nanowire growth using an aluminum catalyst were studied by growing nanowires in hydrogen and hydrogen/nitrogen carrier gas mixtures at different total reactor pressures. Nanowires grown in the nitrogen/hydrogen mixture have faceted catalyst droplet tips, minimal evidence of aluminum diffusion from the tip down the nanowire sidewalls, and significant vapor–solid deposition of silicon on the sidewalls. In comparison, wires grown in pure hydrogen show less well-defined tips, evidence of aluminum diffusion down the nanowire sidewalls at increasing reactor pressures and reduced vapor–solid deposition of silicon on the sidewalls. The results are explained in terms of a model wherein the hydrogen partial pressure plays a critical role in aluminum-catalyzed nanowire growth by controlling hydrogen termination of the silicon nanowire sidewalls. For a given reactor pressure, increased hydrogen partial pressures increase the extent of hydrogen termination of the sidewalls which suppresses SiH_4 adsorption thereby reducing vapor–solid deposition of silicon but increases the surface diffusion length of aluminum. Conversely, lower hydrogen partial pressures reduce the hydrogen termination and also increase the extent of SiH_4 gas phase decomposition, shifting the nanowire growth window to lower growth temperatures and silane partial pressures. (paper)

  4. Development of gas cooled reactors and experimental setup of high temperature helium loop for in-pile operation

    Miletić, Marija, E-mail: marija_miletic@live.com [Czech Technical University in Prague, Prague (Czech Republic); Fukač, Rostislav, E-mail: fuk@cvrez.cz [Research Centre Rez Ltd., Rez (Czech Republic); Pioro, Igor, E-mail: Igor.Pioro@uoit.ca [University of Ontario Institute of Technology, Oshawa (Canada); Dragunov, Alexey, E-mail: Alexey.Dragunov@uoit.ca [University of Ontario Institute of Technology, Oshawa (Canada)

    2014-09-15

    Highlights: • Gas as a coolant in Gen-IV reactors, history and development. • Main physical parameters comparison of gas coolants: carbon dioxide, helium, hydrogen with water. • Forced convection in turbulent pipe flow. • Gas cooled fast reactor concept comparisons to very high temperature reactor concept. • High temperature helium loop: concept, development, mechanism, design and constraints. - Abstract: Rapidly increasing energy and electricity demands, global concerns over the climate changes and strong dependence on foreign fossil fuel supplies are powerfully influencing greater use of nuclear power. In order to establish the viability of next-generation reactor concepts to meet tomorrow's needs for clean and reliable energy production the fundamental research and development issues need to be addressed for the Generation-IV nuclear-energy systems. Generation-IV reactor concepts are being developed to use more advanced materials, coolants and higher burn-ups fuels, while keeping a nuclear reactor safe and reliable. One of the six Generation-IV concepts is a very high temperature reactor (VHTR). The VHTR concept uses a graphite-moderated core with a once-through uranium fuel cycle, using high temperature helium as the coolant. Because helium is naturally inert and single-phase, the helium-cooled reactor can operate at much higher temperatures, leading to higher efficiency. Current VHTR concepts will use fuels such as uranium dioxide, uranium carbide, or uranium oxycarbide. Since some of these fuels are new in nuclear industry and due to their unknown properties and behavior within VHTR conditions it is very important to address these issues by investigate their characteristics within conditions close to those in VHTRs. This research can be performed in a research reactor with in-pile helium loop designed and constructed in Research Center Rez Ltd. One of the topics analyzed in this article are also physical characteristic and benefits of gas

  5. Diffusion-controlled regime of surface-wave-produced plasmas in helium gas

    Berndt, J; Makasheva, K; Schlueter, H; Shivarova, A

    2002-01-01

    The study presents a numerical fluid-plasma model of diffusion-controlled surface-wave-sustained discharges in helium gas. The self-consistent behaviour of the discharge based on the interrelation between plasma density and Θ, the power absorbed on average by one electron, is described. The nonlinear process of step ionization in the charged particle balance equation is the main factor, which ensures the self-consistency. However, it is shown that in helium discharges, the ionization frequencies enter the dependence of Θ on the plasma density also through the ambipolar-diffusion coefficient. Results at two different values of the gas pressure and of the wave frequency are discussed. The lower value of the gas pressure is chosen according to the condition to have a pure diffusion-controlled regime without interference with a transition to the free-fall regime. The boundary condition for the ion flux at the wall sheath is used for determination of the value of μ, the quantity denoting the degree of the radial plasma-density inhomogeneity which, together with the electron-neutral elastic collision frequency, influences the wave propagation characteristics. The two values of the wave frequency chosen provide descriptions of high-frequency and microwave discharges. The model results in the self-consistent structure of the discharge: interrelated variations along the discharge length of wavenumber, space damping rate, Θ, plasma density and electron temperature. The power necessary for sustaining discharges of a given length is also calculated. Comparisons with argon discharges are shown

  6. Study on restriction method for end-wall boundary layer thickness in axial helium gas compressor for gas turbine high temperature gas cooled reactor

    Takada, Shoji; Takizuka, Takakazu; Yan, Xing; Kunitomi, Kazuhiko; Inagaki, Yoshiyuki

    2009-01-01

    Aerodynamic performance test was carried out using a 1/3 scale, 4-stage model of the helium gas compressor to investigate an effect of end-wall over-camber to prevent decrease of axial velocity in the end-wall boundary layer. The model compressor consists of a rotor, 500 mm in diameter, which is driven by an electric motor at a rotational speed of 10800 rpm. The rotor blade span of the first stage is 34 mm. The test was carried out under the condition that the helium gas pressure of 0.88 MPa, temperature of 30degC, and mass flow rate of 12.47 kg/s at the inlet. A 3-dimensional aerodynamic code, which was verified using the test data, showed that axial velocity was lowered by using a blade which increased the inlet blade angle around the end-wall region of the casing side in comparison with that using the original design blade, because the inlet flow angle mismatched with the inlet blade angle of the rotor blade, as opposed to the prediction by a conventional air compressor design method. The overall adiabatic efficiency of the full scale 20-stage helium gas compressor was predicted 89.7% from the Reynolds number dependency of the test data by using the original design blade. (author)

  7. Static and transient characteristics of the shaft seal system for helium gas circulator (Part 1)

    Morohoshi, S.; Saki, K.; Nemoto, M.; Taniguchi, S.; Sugimoto, A.; Kojima, M.

    1982-01-01

    A development program of the shaft seal system for the helium circulator supported by water lubricated bearings is presented. A seal system simulating tester and a computer program which can simulate the transient characteristics of a buffer gas seal system were newly introduced, and an investigation was performed experimentally and analytically of the characteristics of water and gas seals and of the buffer gas seal system including the control system. Main results are as follows: (1) Water seals were especially investigated in detail, and it was found that turbulence in water flow through seal clearance and deformation of seal components affected the leakage characteristics of water seals. They should be considered not only to make safety design but also to get optimum design of the seal system. (2) The calculation method for transient response of the buffer gas seal system including the control system was developed. This digital simulating method can well simulate transients encountered in the tester, and it would make a powerful tool for developing a safe seal system under steady state operation conditions and at depressurization accidents in a reactor

  8. Experimental study of the density of the helium-nitrogen gas system at low temperatures.

    Milyutin, V. A.

    2017-11-01

    At the Department of TOT, an experimental setup was created to measure the density of a binary gas system from 100 to 300 K and pressures up to 16 MPa and with any mixture compositions. Experimental density for the helium-nitrogen system were determined by the piezometer of constant volume method. The amount of substance in the piezometer was measured by volumetric method. In this setup, the mixture of He - N2 was prepared in a special mixer for a series of p-v-T experiments, the concentration was determined by calculation using the equations of state of pure components. In the experiment, mixtures were prepared with molar concentrations, lying close to the range: 0.2, 0.4, 0.6 and 0.8.

  9. Emission profiles of K-He exciplexes in cold helium gas

    Allard, N F

    2012-01-01

    Emission spectra of exciplexes composed of a light alkali atom in the first excited state and 4 He atoms have been observed in cryogenic gas in the spectral range from the atomic D lines to 6300 cm −1 . A unified semi-classical theory of line broadening has been used to determine the total profile from the center to the far wings of emission profiles of potassium perturbed by helium at low temperatures and high He density. The agreement of the theoretical peak positions of K*He n exciplexes compared to the experimental determinations is fairly good. Such comparisons provide a critical test of the calculated molecular potentials and the relevance of the theoretical approach which has been used.

  10. Transient heat transfer for helium gas flowing over a horizontal cylinder with exponentially increasing heat input

    Liu, Qiusheng; Fukuda, Katsuya

    2003-01-01

    The transient heat transfer coefficients for forced convection flow of helium gas over a horizontal cylinder were measured under wide experimental conditions. The platinum cylinder with a diameter of 1.0 mm was used as test heater and heated by electric current with an exponentially increasing heat input of Q 0 exp(t/τ). The gas flow velocities ranged from 5 to 35 m/s, the gas temperatures ranged from 25 to 80degC, and the periods of heat generation rate, τ, ranged from 40 ms to 20 s. The surface superheat and heat flux increase exponentially as the heat generation rate increases with the exponential function. It was clarified that the heat transfer coefficient approaches the quasi-steady-state one for the period τ longer than about 1 s, and it becomes higher for the period shorter than around 1 s. The transient heat transfer shows less dependence on the gas flowing velocity when the period becomes very shorter. The gas temperature in this study shows little influence on the heat transfer coefficient. Semi-empirical correlation for quasi-steady-state heat transfer was obtained based on the experimental data. The ratios of transient Nusselt number Nu tr to quasi-steady-state Nusselt number Nu st at various periods, flow velocities, and gas temperatures were obtained. The heat transfer shifts to the quasi-steady-state heat transfer for longer periods and shifts to the transient heat transfer for shorter periods at the same flow velocity. It also approaches the quasi-steady-state one for higher flow velocity at the same period. Empirical correlation for transient heat transfer was also obtained based on the experimental data. (author)

  11. Study on Off-Design Steady State Performances of Helium Gas Turbo-compressor for HTGR-GT

    Qisen Ren; Xiaoyong Yang; Zhiyong Huang; Jie Wang

    2006-01-01

    The high temperature gas-cooled reactor (HTGR) coupled with direct gas turbine cycle is a promising concept in the future of nuclear power development. Both helium gas turbine and compressor are key components in the cycle. Under normal conditions, the mode of power adjustment is to control total helium mass in the primary loop using gas storage vessels. Meanwhile, thermal power of reactor core is regulated. This article analyzes off-design performances of helium gas turbine and compressors for high temperature gas-cooled reactor with gas turbine cycle (HTGR-GT) at steady state level of electric power adjustment. Moreover, performances of the cycle were simply discussed. Results show that the expansion ratio of turbine decreases as electric power reduces but the compression ratios of compressors increase, efficiencies of both turbine and compressors decrease to some extent. Thermal power does not vary consistently with electric power, the difference between these two powers increases as electric power reduces. As a result of much thermal energy dissipated in the temperature modulator set at core inlet, thermal efficiency of the cycle has a widely reduction under partial load conditions. (authors)

  12. Gas turbine structural mounting arrangement between combustion gas duct annular chamber and turbine vane carrier

    Wiebe, David J.; Charron, Richard C.; Morrison, Jay A.

    2016-10-18

    A gas turbine engine ducting arrangement (10), including: an annular chamber (14) configured to receive a plurality of discrete flows of combustion gases originating in respective can combustors and to deliver the discrete flows to a turbine inlet annulus, wherein the annular chamber includes an inner diameter (52) and an outer diameter (60); an outer diameter mounting arrangement (34) configured to permit relative radial movement and to prevent relative axial and circumferential movement between the outer diameter and a turbine vane carrier (20); and an inner diameter mounting arrangement (36) including a bracket (64) secured to the turbine vane carrier, wherein the bracket is configured to permit the inner diameter to move radially with the outer diameter and prevent axial deflection of the inner diameter with respect to the outer diameter.

  13. Operating experience with gas-bearing circulators in a high-pressure helium loop

    Sanders, J.P.; Gat, U.; Young, H.C.

    1988-01-01

    A high-pressure engineering test loop has been designed and constructed at the Oak Ridge National Laboratory for circulating helium through a test chamber at temperatures to 1,000 deg. C. The purpose of this loop is to determine the thermal and structural performance of proposed components for the primary loops of gas-cooled nuclear reactors. Three gas-bearing circulators, mounted in series, provide a maximum volumetric flow of 0.47 m 3 /s and a maximum head of 78 kJ/kg at operating pressures from 0.1 to 10.7 MPa. Control of gaseous impurities in the circulating gas was the significant operating requirement that dictated the choice of a circulator that is lubricated by the circulating gas. The motor for each circulator is contained within the pressure boundary, and it is cooled by circulating the gas in the motor cavity over water-cooled coils. Each motor is rated at 200 kW at a speed of 23,500 rpm. The circulators have been operated in the loop for more than 5,000 h. The flow of the gas in the loop is controlled by varying the speed of the circulators through the use of individual 250-kVA, solid state power supplies that can be continuously varied in frequency from 50 to 400 Hz. To prevent excessive wear on the gas bearings during startup, the circulator motor accelerates the rotor to 3,000 rpm in less than one second. During operation, no problems associated with the gas bearings, per se, were encountered; however, related problems pointed to design considerations that should be included in future applications of circulators of this type. The primary test that has been conducted in this loop required sustained operation for several weeks without interruption. After a number of unscheduled interruptions, the operating goals were attained. During part of this period, the loop was operated with only two circulators installed in the pressure vessels with a guard installed in the third vessel to protect the closure flange from the gas temperatures. Unattended

  14. Design of helium-gas supplying facility of out-of-pile demonstration test for HTTR heat utilization system

    Hino, Ryutaro; Fujisaki, Katsuo; Kobayashi, Toshiaki [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment] [and others

    1996-09-01

    One of the objectives of the High-Temperature Engineering Test Reactor (HTTR) is to demonstrate effectiveness of high-temperature heat utilization. Prior to connect a heat utilization system to the HTTR, a series of out-of-pile demonstration test is indispensable to improve components` performance, to demonstrate operation, control and safety technologies and to verify analysis codes for design and safety evaluation. After critical review and discussion on the out-of-pile demonstration test, a test facility have been designed. In this report, a helium-gas supplying facility simulated the HTTR system was described in detail, which supplies High-temperature helium-gas of 900degC to a steam reforming facility mocking-up the HTTR heat utilization system. Components of the Helium Engineering Demonstration Loop (HENDEL) were selected to reuse in the helium-gas supplying facility in order to decrease construction cost. Structures and specifications of new components such as a high-temperature heater and a preheater were decided after evaluation of thermal and hydraulic performance and strength. (author)

  15. Helium Isotopes and Noble Gas Abundances of Cave Dripping Water in Three Caves in East Asia

    Chen, A. T.; Shen, C. C.; Tan, M.; Li, T.; Uemura, R.; Asami, R.

    2015-12-01

    Paleo-temperature recorded in nature archives is a critical parameter to understand climate change in the past. With advantages of unique inert chemical characteristics and sensitive solubilities with temperature, dissolved noble gases in speleothem inclusion water were recently proposed to retrieve terrestrial temperature history. In order to accurately apply this newly-developed speleothem noble gas temperature (NGT) as a reliable proxy, a fundamental issue about behaviors of noble gases in the karst should be first clarified. In this study, we measured noble gas contents in air and dripping water to evaluate any ratio deviation between noble gases. Cave dripping water samples was collected from three selected caves, Shihua Cave in northern China, Furong Cave in southwestern, and Gyukusen Cave in an island located in the western Pacific. For these caves are characterized by a thorough mixing and long-term storage of waters in a karst aquifer by the absence of seasonal oxygen isotope shifts. Ratios of dripping water noble gases are statistically insignificant from air data. Helium isotopic ratios in the dripping water samples match air value. The results indicate that elemental and isotopic signatures of noble gases from air can be frankly preserved in the epikarst and support the fidelity of NGT techniques.

  16. Preliminary safety evaluation of the Gas Turbine-Modular Helium Reactor (GT-MHR)

    Dunn, T.D.; Lommers, L.J.; Tangirala, V.E.

    1994-04-01

    A qualitative comparison between the safety characteristics of the Gas Turbine-Modular Helium Reactor (GT-MHR) and those of the steam cycle shows that the two designs achieve equivalent levels of overall safety performance. This comparison is obtained by applying the scaling laws to detailed steam-cycle computations as well as the conclusions obtained from preliminary GT-MHR model simulations. The gas turbine design is predicted to be superior for some event categories, while the steam cycle design is better for others. From a safety perspective, the GT-MHR has a modest advantage for pressurized conduction cooldown events. Recent computational simulations of 102 column, 550 MW(t) GT-MHR during a depressurized conduction cooldown show that peak fuel temperatures are within the limits. The GT-MHR has a significantly lower risk due to water ingress events under operating conditions. Two additional scenarios, namely loss of load event and turbine deblading event that are specific to the GT-MHR design are discussed. Preliminary evaluation of the GT-MHR's safety characteristics indicate that the GT-MHR can be expected to satisfy or exceed its safety requirements

  17. The gas turbine-modular helium reactor (GT-MHR), high efficiency, cost competitive, nuclear energy for the next century

    Zgliczynski, J.B.; Silady, F.A.; Neylan, A.J.

    1994-04-01

    The Gas Turbine-Modular Helium Reactor (GT-MHR) is the result of coupling the evolution of a small passively safe reactor with key technology developments in the US during the last decade: large industrial gas turbines, large active magnetic bearings, and compact, highly effective plate-fin heat exchangers. The GT-MHR is the only reactor concept which provides a step increase in economic performance combined with increased safety. This is accomplished through its unique utilization of the Brayton cycle to produce electricity directly with the high temperature helium primary coolant from the reactor directly driving the gas turbine electrical generator. This cannot be accomplished with another reactor concept. It retains the high levels of passive safety and the standardized modular design of the steam cycle MHTGR, while showing promise for a significant reduction in power generating costs by increasing plant net efficiency to a remarkable 47%

  18. Low-cycle fatigue of heat-resistant alloys in high-temperature gas-cooled reactor helium

    Tsuji, H.; Kondo, T.

    1984-01-01

    Strain controlled low-cycle fatigue tests were conducted on four nickel-base heat-resistant alloys at 900 0 C in simulated high-temperature gas-cooled reactor (HTGR) environments and high vacuums of about 10 -6 Pa. The observed behaviors of the materials were different and divided into two groups when tests were made in simulated HTGR helium, while all materials behaved similarly in vacuums. The materials that have relatively high ductility and compatibility with impure helium at test temperature showed considerable resistance to the fatigue damage in impure helium. On the other hand, the alloys qualified with their high creep strength were seen to suffer from the adverse effects of impure helium and the trend of intergranular cracking as well. The results were analyzed in terms of their susceptibility to the environmentenhanced fatigue damage by examining the ratios of the performance in impure helium to in vacuum. The materials that showed rather unsatisfactory resistance were considered to be characterized by their limited ductility partly due to their coarse grain structure and susceptibility to intergranular oxidation. Moderate carburization was commonly noted in all materials, particularly at the cracked portions, indicating that carbon intrusion had occurred during the crack growth stage

  19. High-Temperature Corrosion Behavior of Alloy 617 in Helium Environment of Very High Temperature Gas Reactor

    Lee, Gyeong-Geun; Jung, Sujin; Kim, Daejong; Jeong, Yong-Whan; Kim, Dong-Jin

    2012-01-01

    Alloy 617 is a Ni-base superalloy and a candidate material for the intermediate heat exchanger (IHX) of a very high temperature gas reactor (VHTR) which is one of the next generation nuclear reactors under development. The high operating temperature of VHTR enables various applications such as mass production of hydrogen with high energy efficiency. Alloy 617 has good creep resistance and phase stability at high temperatures in an air environment. However, it was reported that the mechanical properties decreased at a high temperature in an impure helium environment. In this study, high-temperature corrosion tests were carried out at 850°C-950°C in a helium environment containing the impurity gases H_2, CO, and CH_4, in order to examine the corrosion behavior of Alloy 617. Until 250 h, Alloy 617 specimens showed a parabolic oxidation behavior at all temperatures. The activation energy for oxidation in helium environment was 154 kJ/mol. The SEM and EDS results elucidated a Cr-rich surface oxide layer, Al-rich internal oxides and depletion of grain boundary carbides. The thickness and depths of degraded layers also showed a parabolic relationship with time. A normal grain growth was observed in the Cr-rich surface oxide layer. When corrosion tests were conducted in a pure helium environment, the oxidation was suppressed drastically. It was elucidated that minor impurity gases in the helium would have detrimental effects on the high temperature corrosion behavior of Alloy 617 for the VHTR application.

  20. Adsorption removal of carbon dioxide from the helium coolant of high-temperature gas-cooled reactors

    Varezhin, A.V.; Fedoseenkov, A.N.; Khrulev, A.A.; Metlik, I.V.; Zel venskii, Y.D.

    1986-01-01

    This paper conducts experiments on the removal of CO 2 from helium by means of a Soviet-made adsorbent under the conditions characteristic of high-temperature gas-cooled reactor cleaning systems. The adsorption of CO 2 from helium was studied under dynamic conditions with a fixed layer of adsorbent in a flow-through apparatus with an adsorber 16 mm in diameter. The analysis of the helium was carried out by means of a TVT chromatograph. In order to compare the adsorption of CO 2 on CaA zeolite under dynamic conditions from the helium stream under pressure with the equilibrium adsorption on the basis of pure CO 2 , the authors determined the adsorption isotherm at 293 K by the volumetric method over a range of CO 2 equilibrium pressures from 260 to 11,970 Pa. Reducing the adsorption temperature to 273 K leads to a considerable reduction in the energy costs for regeneration, owing to the increase in adsorption and the decrease in the number of regeneration cycles; the amount of the heating gas used is reduced to less than half

  1. Production of ammonia from plasma-catalytic decomposition of urea: Effects of carrier gas composition.

    Fan, Xing; Li, Jian; Qiu, Danqi; Zhu, Tianle

    2018-04-01

    Effects of carrier gas composition (N 2 /air) on NH 3 production, energy efficiency regarding NH 3 production and byproducts formation from plasma-catalytic decomposition of urea were systematically investigated using an Al 2 O 3 -packed dielectric barrier discharge (DBD) reactor at room temperature. Results show that the presence of O 2 in the carrier gas accelerates the conversion of urea but leads to less generation of NH 3 . The final yield of NH 3 in the gas phase decreased from 70.5%, 78.7%, 66.6% and 67.2% to 54.1%, 51.7%, 49.6% and 53.4% for applied voltages of 17, 19, 21 and 23kV, respectively when air was used as the carrier gas instead of N 2 . From the viewpoint of energy savings, however, air carrier gas is better than N 2 due to reduced energy consumption and increased energy efficiency for decomposition of a fixed amount of urea. Carrier gas composition has little influence on the major decomposition pathways of urea under the synergetic effects of plasma and Al 2 O 3 catalyst to give NH 3 and CO 2 as the main products. Compared to a small amount of N 2 O formed with N 2 as the carrier gas, however, more byproducts including N 2 O and NO 2 in the gas phase and NH 4 NO 3 in solid deposits were produced with air as the carrier gas, probably due to the unproductive consumption of NH 3 , the possible intermediate HNCO and even urea by the abundant active oxygen species and nitrogen oxides generated in air-DBD plasma. Copyright © 2017. Published by Elsevier B.V.

  2. Targets Involved in Cardioprotection by the Non-Anesthetic Noble Gas Helium

    Weber, Nina C.; Smit, Kirsten F.; Hollmann, Markus W.; Preckel, Benedikt

    2015-01-01

    Research data from the past decade indicate that noble gases like xenon and helium exert profound cardioprotection when applied before, during or after organ ischemia. Of all noble gases, especially helium, has gained interest in the past years because it does not have an anesthetic "side effect"

  3. Cryodeposition of nitrogen gas on a surface cooled by helium II

    Dhuley, R. C.; Bosque, E. S.; Van Sciver, S. W.

    2014-01-01

    Catastrophic loss of beam tube vacuum in a superconducting particle accelerator can be simulated by sudden venting of a long high vacuum channel cooled on its outer surface by He II. The rapid rush of atmospheric air in such an event shows an interesting propagation effect, which is much slower than the shock wave that occurs with vacuum loss at ambient conditions. This is due to flash frosting/deposition of air on the cold walls of the channel. Hence to characterize the propagation as well as the associated heat transfer, it is first necessary to understand the deposition process. Here we attempt to model the growth of nitrogen frost layer on a cold plate in order to estimate its thickness with time. The deposition process can be divided into two regimes- free molecular and continuum. It is shown that in free molecular regime, the frost growth can be modeled reasonably well using cryopump theory and general heat transfer relations. The continuum regime is more complex to model, given the higher rate of gas incident on cryosurface causing a large heat load on helium bath and changing cryosurface temperature. Results from the continuum regime are discussed in the context of recent experiments performed in our laboratory

  4. Heat transfer in a compact heat exchanger containing rectangular channels and using helium gas

    Olson, D. A.

    1991-01-01

    Development of a National Aerospace Plane (NASP), which will fly at hypersonic speeds, require novel cooling techniques to manage the anticipated high heat fluxes on various components. A compact heat exchanger was constructed consisting of 12 parallel, rectangular channels in a flat piece of commercially pure nickel. The channel specimen was radiatively heated on the top side at heat fluxes of up to 77 W/sq cm, insulated on the back side, and cooled with helium gas flowing in the channels at 3.5 to 7.0 MPa and Reynolds numbers of 1400 to 28,000. The measured friction factor was lower than that of the accepted correlation for fully developed turbulent flow, although the uncertainty was high due to uncertainty in the channel height and a high ratio of dynamic pressure to pressure drop. The measured Nusselt number, when modified to account for differences in fluid properties between the wall and the cooling fluid, agreed with past correlations for fully developed turbulent flow in channels. Flow nonuniformity from channel-to-channel was as high as 12 pct above and 19 pct below the mean flow.

  5. Cryodeposition of nitrogen gas on a surface cooled by helium II

    Dhuley, R. C.; Bosque, E. S.; Van Sciver, S. W. [Cryogenics Group, National High Magnetic Field Laboratory, Tallahassee, FL 32310 USA and Mechanical Engineering Department, FAMU-FSU College of Engineering, Tallahassee, FL 32310 (United States)

    2014-01-29

    Catastrophic loss of beam tube vacuum in a superconducting particle accelerator can be simulated by sudden venting of a long high vacuum channel cooled on its outer surface by He II. The rapid rush of atmospheric air in such an event shows an interesting propagation effect, which is much slower than the shock wave that occurs with vacuum loss at ambient conditions. This is due to flash frosting/deposition of air on the cold walls of the channel. Hence to characterize the propagation as well as the associated heat transfer, it is first necessary to understand the deposition process. Here we attempt to model the growth of nitrogen frost layer on a cold plate in order to estimate its thickness with time. The deposition process can be divided into two regimes- free molecular and continuum. It is shown that in free molecular regime, the frost growth can be modeled reasonably well using cryopump theory and general heat transfer relations. The continuum regime is more complex to model, given the higher rate of gas incident on cryosurface causing a large heat load on helium bath and changing cryosurface temperature. Results from the continuum regime are discussed in the context of recent experiments performed in our laboratory.

  6. Helium circulator design concepts for the modular high temperature gas-cooled reactor (MHTGR) plant

    McDonald, C.F.; Nichols, M.K.; Kaufman, J.S.

    1988-01-01

    Two helium circulators are featured in the Modular High-Temperature Gas-Cooled Reactor (MHTGR) power plant - (1) the main circulator, which facilitates the transfer of reactor thermal energy to the steam generator, and (2) a small shutdown cooling circulator that enables rapid cooling of the reactor system to be realized. The 3170 kW(e) main circulator has an axial flow compressor, the impeller being very similar to the unit in the Fort St. Vrain (FSV) plant. The 164 kW(e) shutdown cooling circulator, the design of which is controlled by depressurized conditions, has a radial flow compressor. Both machines are vertically oriented, have submerged electric motor drives, and embody rotors that are supported on active magnetic bearings. As outlined in this paper, both machines have been conservatively designed based on established practice. The circulators have features and characteristics that have evolved from actual plant operating experience. With a major goal of high reliability, emphasis has been placed on design simplicity, and both machines are readily accessible for inspection, repair, and replacement, if necessary. In this paper, conceptual design aspects of both machines are discussed, together with the significant technology bases. As appropriate for a plant that will see service well into the 21st century, new and emerging technologies have been factored into the design. Examples of this are the inclusion of active magnetic bearings, and an automated circulator condition monitoring system. (author). 18 refs, 20 figs, 13 tabs

  7. Studies of Helium Based Gas Mixtures Using a Small Cell Drift Chamber

    Heise, Jaret; British Columbia U.

    2006-01-01

    An international collaboration is currently working on the construction and design of an asymmetric B Factory at the Stanford Linear Accelerator Center that will be ready to collect data in 1999. The main physics motivation for such a facility is to test the description and mechanism of CP violation in the Standard Model of particle physics and provide insight into the question of why more matter than antimatter is observed in the universe today. In particular, this experiment will measure CP violation in the decay of B mesons. In the early stages of this effort, the Canadian contingent proposed to build the central tracking chamber for the BABAR detector. Presently, a prototype drift chamber is in operation and studies are being performed to test some of the unique features of drift chamber design dictated by the conditions of the experiment. Using cosmic muons, it is possible to study tracking and pattern recognition in the prototype chamber, and therefore calculate the efficiency and spatial resolution of the prototype chamber cells. These performance features will be used to test whether or not the helium-based gas mixtures proposed for the BABAR drift chamber are a viable alternative to the more traditional argon-based gases

  8. An X-ray beam position monitor based on the photoluminescence of helium gas

    Revesz, Peter; White, Jeffrey A.

    2005-03-01

    A new method for white beam position monitoring for both bend magnet and wiggler synchrotron X-ray radiation has been developed. This method utilizes visible light luminescence generated as a result of ionization by the intense X-ray flux. In video beam position monitors (VBPMs), the luminescence of helium gas at atmospheric pressure is observed through a view port using a CCD camera next to the beam line. The beam position, profile, integrated intensity and FWHM are calculated from the distribution of luminescence intensity in each captured image by custom software. Misalignment of upstream apertures changes the image profile making VBPMs helpful for initial alignment of upstream beam line components. VBPMs can thus provide more information about the X-ray beam than most beam position monitors (BPMs). A beam position calibration procedure, employing a tilted plane-parallel glass plate placed in front of the camera lens, has also been developed. The accuracy of the VBPM system was measured during a bench-top experiment to be better than 1 μm. The He-luminescence-based VBPM system has been operative on three CHESS beam lines (F hard-bend and wiggler, A-line wiggler and G-line wiggler) for about a year. The beam positions are converted to analog voltages and used as feedback signals for beam stabilization. In our paper we discuss details of VBPM construction and describe further results of its performance.

  9. The gas turbine modular helium reactor. An international project to develop a safe, efficient, flexible product

    Silberstein, A.J.

    1998-01-01

    As originally scheduled, the Conceptual Design Report of the 600 Mwt Gas Turbine Modular Helium Reactor has been issued in October 1997 by OKBM in Nizhny Novgorod, a keystone Russian Engineering Institute fully involved in the realization of this International Project. The plutonium burning, graphite moderated helium cooled reactor design results from the work done on the basis of General Atomics original concept combined with the goal of optimizing safety power and efficiency with multi contributions in specific fields from the Russian organizations: MINATOM, OKBM, VNIINM, Lutch, Kurchatov Institute, Seversk Chemical Combinat, Fuji Electric and FRAMATOME. The objective to concentrate the engineering work in Russia has met a full success due principally to the quality and experience of the people, to the international support and to the progressive integration of new techniques of communication, of project management culture and utilization of modern computerized design tools and methods. To day the best international standard of quality is reached in the engineering activity and expected to stay at this level for future developments, when including experimental facilities operation and components manufacturing activities, thanks to the diffusion of the common culture, acquired by the main actors during the conceptual design phase, that will be exported to Russian third parties. At this stage we are planning to start design verification and sensitive components and systems qualification, with the same original actors. The European Commission has already shown some significant interest through the MICHELANGELO Initiative in supporting the HTR concepts assessment and identification of the R and D needs. We are looking forward for further support from the International Community and particularly from European Institutions in the frame of the 5th PCRD to pursue the GT MHR R and D program. Furthermore we are looking for funding the building of a prototype in Russia

  10. The subcontinental mantle beneath southern New Zealand, characterised by helium isotopes in intraplate basalts and gas-rich springs

    Hoke, L.; Poreda, R.; Reay, A.; Weaver, S. D.

    2000-07-01

    New helium isotope data measured in Cenozoic intraplate basalts and their mantle xenoliths are compared with present-day mantle helium emission on a regional scale from thermal and nonthermal gas discharges on the South Island of New Zealand and the offshore Chatham Islands. Cenozoic intraplate basaltic volcanism in southern New Zealand has ocean island basalt affinities but is restricted to continental areas and absent from adjacent Pacific oceanic crust. Its distribution is diffuse and widespread, it is of intermittent timing and characterised by low magma volumes. Most of the 3He/ 4He ratios measured in fluid inclusions in mantle xenocrysts and basalt phenocrysts such as olivine, garnet, and amphibole fall within the narrow range of 8.5 ± 1.5 Ra (Ra is the atmospheric 3He/ 4He ratio) with a maximum value of 11.5 Ra. This range is characteristic of the relatively homogeneous and degassed upper MORB-mantle helium reservoir. No helium isotope ratios typical of the lower less degassed mantle (>12 Ra), such as exemplified by the modern hot-spot region of Hawaii (with up to 32 Ra) were measured. Helium isotope ratios of less than 8 Ra are interpreted in terms of dilution of upper mantle helium with a radiogenic component, due to either age of crystallisation or small-scale mantle heterogeneities caused by mixing of crustal material into the upper mantle. The crude correlation between age of samples and helium isotopes with generally lower R/Ra values in mantle xenoliths compared with host rock phenocrysts and the in general depleted Nd and Sr isotope ratios and the light rare earth element enrichment of the basalts supports derivation of melts as small melt fractions from a depleted upper mantle, with posteruptive ingrowth of radiogenic helium as a function of lithospheric age. In comparison, the regional helium isotope survey of thermal and nonthermal gas discharges of the South Island of New Zealand shows that mantle 3He anomalies in general do not show an obvious

  11. Effect of helium gas pressure on dc conduction mechanism and EMI shielding properties of nanocrystalline carbon thin films

    Rawal, Ishpal, E-mail: rawalishpal@gmail.com [Department of Physics, Kirori Mal College, University of Delhi, Delhi 110007 (India); Panwar, O.S., E-mail: ospanwar@mail.nplindia.ernet.in [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Tripathi, R.K. [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Singh, Avanish Pratap; Dhawan, S.K. [Polymeric and Soft Materials Group, Physics Engineering of Carbon, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Srivastava, A.K. [Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)

    2015-05-05

    This paper reports the effect of helium partial pressures ∼1.2 × 10{sup −5} (base pressure), 1.4 × 10{sup −4}, 8.6 × 10{sup −3} and 0.1 mbar on the variable range hopping conduction in nanocrystalline carbon thin films deposited by filtered cathodic jet carbon arc technique. High resolution transmission electron microscopy studies suggest the random distribution of nanocrystallites (∼3–7 nm) in the amorphous matrix. The DC conduction behavior of the deposited nanocrystalline films has been studied in the light of Mott's variable range hopping (VRH) model and found to obey three dimensional VRH conduction. The randomly distributed nanocrystallites in amorphous matrix may lead to change in the distribution of density of states near Fermi level and hence, the conduction behavior. The enhanced electrical conductivity of the deposited films due to the helium environment makes them suitable for electromagnetic interference shielding applications. The sample deposited at a helium partial pressure of 0.1 mbar has a value of shielding effectiveness ∼7.84 dB at 18 GHz frequency. - Highlights: • Nanocrystalline carbon thin films (NCTF) has been deposited by FCJCA technique. • Effect of helium gas pressure has been studied on the properties of NCTF. • Investigation of EMI shielding properties of NCTF has been carried out.

  12. Homogeneous Nucleation Rate Measurements of 1-Propanol in Helium: The Effect of Carrier Gas Pressure

    Brus, David; Ždímal, Vladimír; Stratmann, F.

    2006-01-01

    Roč. 124, č. 16 (2006), Art. No. 164306 ISSN 0021-9606 R&D Projects: GA AV ČR(CZ) IAA2076203 Institutional research plan: CEZ:AV0Z40720504 Keywords : diffusion cloud-chamber * supersaturated vapor * background gases Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.166, year: 2006

  13. Preliminary study on application of Pd composite membrane in helium purification system of high-temperature gas-cooled reactor

    Cai Jianhua; Yang Xiaoyong; Wang Jie; Yu Suyuan

    2008-01-01

    Helium purification system (HPS) is the main part of the helium auxiliary system of high-temperature gas-cooled reactors (HTGR), also in fusion reactors. Some exploratory work was carried out on the application of Pd composite membrane in the separation of He and H 2 . A typical single stripper permeator with recycle (SSP) system was designed, based on the design parameters of a small scale He purification test system CIGNE in CADARACHE, CEA, France, and finite element analysis method was used to solve the model. The total length of membrane module is fixed to 0.5 m. The results show that the concentration of H 2 is found to reduce from 1 000 μL/L in feed gas to 5 μL/L in the product He (the upper limitation of HPS in HTGR). And the molar ratio of product He to feed gas is 96.18% with the optimized ratio of sweep gas to retentive gas 0. 3970. It's an exponential distribution of H 2 concentration along the membrane module. The results were also compared with the other two popular designs, two stripper in series permeator (TSSP) and continuous membrane column (CMC). (authors)

  14. Gas-workers not wonts by only carriers

    Hirman, K.

    2003-01-01

    Paper deals with the own production of the co-owner of the Slovensky plynarensky podnik, a. s. (SPP). Gas de France mines gas in North Sea shelf. Algeria and Egypt should become the important source in next years. Ruhrgas also mines in North Sea. It owns 6.5% part in Gazprom. Ruhrgaz is interested in gas production directly in Russian Federation. Preliminary discussions are going hand in hand with Lukoil and Sevmorneftegaz companies. Lukoil supposes that possible attendance of Ruhrgas should help to get necessary capital of 1.5 billions Euro. Ruhrgaz is interested in gigantic Shtokmanovskoe deposit in Barents Sea shelf of Sevmorneftegaz Company. Total capital costs are estimated to 18 billions USD. But one of the problems remaining is closed statute of this part of Russian Arctic. Gazprom is also interested in new sources. Gazprom signed contract with Turkmenistan. Gazprom will purchase two trillions m 3 of gas until 2028 in accordance with it. In present time the export to Europe represents 135 billions m 3 annually, but according to signed long-term contracts this capacity will increase up to 180 billions m 3 after 2008. Because the domestic Russian mining is descending or stagnating, Gazprom is unable to start exploitation of new gigantic deposits in Yamal, company is forced to cover threatening deficit of gas by deliveries from Turkmenistan, Uzbekistan and Kazakhstan. So the possible competition of these countries is simultaneously eliminated in international markets. (Author)

  15. Thermal fluid dynamic behavior of coolant helium gas in a typical reactor VHTGR channel of prismatic core

    Belo, Allan Cavalcante

    2016-01-01

    The current studies about the thermal fluid dynamic behavior of the VHTGR core reactors of 4 th generation are commonly developed in 3-D analysis in CFD (computational fluid dynamics), which often requires considerable time and complex mathematical calculations for carrying out these analysis. The purpose of this project is to achieve thermal fluid dynamic analysis of flow of gas helium refrigerant in a typical channel of VHTGR prismatic core reactor evaluating magnitudes of interest such as temperature, pressure and fluid velocity and temperature distribution in the wall of the coolant channel from the development of a computer code in MATLAB considering the flow on one-dimensional channel, thereby significantly reducing the processing time of calculations. The model uses three different references to the physical properties of helium: expressions given by the KTA (German committee of nuclear safety standards), the computational tool REFPROP and a set of constant values for the entire channel. With the use of these three references it is possible to simulate the flow treating the gas both compressible and incompressible. The results showed very close values for the interest quantities and revealed that there are no significant differences in the use of different references used in the project. Another important conclusion to be observed is the independence of helium in the gas compressibility effects on thermal fluid dynamic behavior. The study also indicated that the gas undergoes no severe effects due to high temperature variations in the channel, since this goes in the channel at 914 K and exits at approximately 1263 K, which shows the excellent use of helium as a refrigerant fluid in reactor channels VHTGR. The comparison of results obtained in this work with others in the literature served to confirm the effectiveness of the one-dimensional consideration of method of gas flow in the coolant channel to replace the models made in 3-D for the pressure range and

  16. Challenges of LNG (Liquefied Natural Gas Carriers in 21" Century

    Marina Zanne

    2009-01-01

    Full Text Available Natural gas is relatively cheap, environmentally friendlyand energetically efficient fossil fuel that is gaining in attractivenessdaily as it can be used in many sectors. As not all consumerscan be reached by pipelines the technique of transp01tingnatural gas in the liquefied form has been developed at the beginningof 20th century but it was only in 1959 that the firstoverseas transport of liquefied natural gas ( LN G occurred. Inthe fifty years of operation LNG shipping has shown immaculatesafety records. LNG tankers can be described only in superlatives;they are without any doubt the most sophisticated and·expensive ships that sail around the globe, they demand specialattention when navigating to or out of harbours and need to bemanned with the most educated and experienced crew. LNGmarket is expanding and changing; demand is surpassing theproductivity, new importing and exporting countries appear,LNG fleet is growing in capacity and number at high pace, exploitationcontracts for the ships are being modified giving theopportunity for new companies to enter( . .. . The paper givesan overview on liquefied natural gas market and the historic developmentof LNG shipping. It focuses on the recent boom inLNG shipping and emphasises questions concerning the safety,crewing and exploitation of the LNG tankers in the future.

  17. Some research and development on power plants with helium gas turbine units

    Kaplan, M.P.

    1983-01-01

    Research and development projects pursued at the S. M. Kirov Kharkov Turbine Factory Production Association for Nuclear Turbomachinery Manufacturing have probed into prospective use of helium as the working medium in nuclear power facilities. The projects under study are compared mainly in terms of heat efficiency. Solutions are also being sought for problems centering around high efficiency in helium turbocompressors combined with shortening of axial dimensions. Different types of power plants are being compared with attention given to features of the flow passages of turbocompressors. The projects were developed for helium temperatures and pressures downstream of the reactor 950 0 C and 4.8 MPa, and thermal reactor output 2250 MW(th). The reactor is assumed to be served by two turbine plants in the turbocompressor designs

  18. Utilization of thorium in a Gas Turbine – Modular Helium Reactor

    Şahin, Hacı Mehmet; Erol, Özgür; Acır, Adem

    2012-01-01

    Highlights: ► Performance parameters for the original fuel in GT-MHR depending on time were found. ► A proper plutonium–thorium mixture ratio was found using the original fuel results. ► Performance comparison of plutonium mixture and original fuel was made. ► Comparison showed that weapons grade plutonium mixture can be used in the reactor. - Abstract: Gas Turbine-Modular Helium Reactor (GT-MHR) is one of the new types of the reactors with high efficiency and increased safety features. The usage of different kinds of fissile material in this reactor can increase the life of it. Weapons-grade plutonium (WGrPu), which can be acquired from the old dismantled nuclear weapons, can be an option in a GT-MHR. In order to increase the sustainability of the WGrPu resources this fuel can be mixed with thorium, which is a fertile material that can be found in the nature and has resources three times more than uranium. In this study, possibility of utilization of the weapons-grade plutonium–thorium mixture was investigated and an optimum mixture ratio was determined. The behavior of this mixture and the original fuel was studied by using MCNP5 1.4, Monteburns 2.0 and Origen 2.2 tools. Calculations showed that, a GT-MHR type reactor, which is using the original TRISO fuel particle mixture of 20% enriched uranium + natural uranium (original fuel) has an effective multiplication factor (k eff ) of 1.270. Corresponding to this k eff value the weapons grade plutonium/thorium oxide mixture was found 19%/81%. By using Monteburns Code, the operation time, which describes the time passed until the reactor reaches a k eff value of 1.02, was found as 515 days for the original fuel and 1175 days for the weapons grade plutonium mixture. Furthermore, the burn-up values for the original fuel and WGrPu fuels were found as 47.69 and 119.27 GWd/MTU, respectively.

  19. The diffusion cross section for atomic hydrogen in helium gas at low temperature and the H-He potential

    Jochemsen, R.; Berlinsky, A.J.; Hardy, W.N.

    1984-01-01

    A calculation of the diffusion cross section Q sub(D) of hydrogen atoms in helium gas at low temperature is performed and compared with recent experimental results. The comparison allows an improved determination of the H-He potential. Calculations were done for three different potentials: our own empirical potential based on experimental high-energy scattering results and calculated long-range dispersion terms, which gives good results for Q sub(D) and total collision cross sections; a recently determined semi-empirical potential, and an ab initio calculated potential. All three potentials imply a strong temperature dependence of Q sub(D) for T < 1.5 K

  20. Dynamic simulation for scram of high temperature gas-cooled reactor with indirect helium turbine cycle system

    Li Wenlong; Xie Heng

    2011-01-01

    A dynamic analysis code for this system was developed after the mathematical modeling and programming of important equipment of 10 MW High Temperature Gas Cooled Reactor Helium Turbine Power Generation (HTR-10GT), such as reactor core, heat exchanger and turbine-compressor system. A scram accident caused by a 0.1 $ reactivity injection at 5 second was simulated. The results show that the design emergency shutdown plan for this system is safe and reasonable and that the design of bypass valve has a large safety margin. (authors)

  1. Electron induced formation and stability of molecular and cluster ions in gas phase and superfluid helium nanodroplets

    Aleem, M. A.

    2010-01-01

    The present PhD thesis represents a broad range study of electron induced formation and stability of positive and negative ions in gas phase and superfluid helium nanodroplets. The molecules studied are of industrial, environmental, plasma and biological relevance. The knowledge obtained from the study provides new insight for the proper understanding and control on energetics and dynamics of the reactions involved in the formation and fragmentation processes of the studied molecules and clusters. The experiments are accomplished and investigated using mass spectrometric techniques for the formation of molecular and cluster ions using different mass spectrometers available in our laboratory. One part of the work is focused on electron-induced reactions of the molecules in gas phase. Especially focus is laid to electron attachment to the isomers of mononitrotolouene used as an additive to explosives. The fragile nature and high internal energy of these molecules has lead to extensive fragmentation following the ionisation process. Dissociative electron attachment to the three different isomers has shown different resonances and therefore this process can be utilized to explicitly distinguish these isomers. Anion efficiency curves of the isomers have been studied using effusive molecular beam source in combination with a hemispherical electron monochromator as well as a Nier-type ion source attached to a sector field mass spectrometer. The outcome of the experiment is a reliable and effective detection method highly desirable for environmental and security reasons. Secondly, dissociative electron ionization of acetylene and propene is studied and their data is directly related to the plasma modelling for plasma fusion and processing reactors. Temperature effects for dissociative electron attachment to halo-hydrocarbons are also measured using a trochoidal electron monochromator. The second part of the work is concerned with the investigation of electron

  2. Evaluation, Comparison and Optimization of the Compact Recuperator for the High Temperature Gas-Cooled Reactor (HTGR) Helium Turbine System

    Hao Haoran; Yang Xiaoyong; Wang Jie; Ye Ping; Yu Xiaoli; Zhao Gang

    2014-01-01

    Helium turbine system is a promising method to covert the nuclear power generated by the High Temperature Gas Cooled Reactor (HTGR) into electricity with inherent safety, compact configuration and relative high efficiency. And the recuperator is one of the key components for the HTGR helium turbine system. It is used to recover the exhaust heat out of turbine and pass it to the helium from high pressure compressor, and hence increase the cycle’s efficiency dramatically. On the other hand, the pressure drop within the recuperator will reduce the cycle efficiency, especially on low pressure side of recuperator. It is necessary to optimize the design of recuperator to achieve better performance of HTGR helium turbine system. However, this optimization has to be performed with the restriction of the size of the pressure vessel which contains the power conversion unit. This paper firstly presents an analysis to investigate the effects of flow channel geometry, recuperator’s power and size on heat transfer and pressure drop. Then the relationship between the recuperator design and system performance is established with an analytical model, followed by the evaluations of the current recuperator designs of GT-MHR, GTHTR300 and PBMR, in which several effective technical measures to optimize the recuperator are compared. Finally it is found that the most important factors for optimizing recuperator design, i.e. the cross section dimensions and tortuosity of flow channel, which can also be extended to compact intermediate heat exchangers. It turns out that a proper optimization can increase the cycle’s efficiency by 1~2 percentage, which could also raise the economy and competitiveness of future commercial HTGR plants. (author)

  3. The Coselle CNG carrier : a new way to ship natural gas by sea

    Stenning, D.

    1999-01-01

    Coselle CNG carriers represent an emerging technology option for water-borne natural gas transportation. The idea behind the Coselle is to create a large but compact CNG storage system using pipe coiled into a carousel. The system promises to significantly improve the economics of shipping natural gas over short sea routes. This would unlock many gas reserves which are stranded because of the high costs associated with shipping natural gas by conventional tankers. The innovative patented technology for Coselle CNG carriers was described in this paper. The completed work on the technology is sufficient to allow a pilot project to proceed before the next step of commercialization of the technology. The technology can be applied in the Mediterranean Sea, the Caribbean Sea, the Arabian Sea, Sakhalin Island, Canada's east coast, Deepwater offshore Brazil and Gulf of Mexico, and West Africa. 4 refs., 1 tab., 5 figs

  4. Power-generating process of obtaining gas-energy carrier and reducer from coal

    Tleugabulov, S.; Duncheva, E.; Zubkevich, M.

    1999-01-01

    The manufacture of power-generating gas has the important economic value for Kazakhstan having large territory, raw and fuel resources especially power coal and clean coal wastes. The technology of reception of gas-energy carrier and reducer from power coal is developed. The basic product of technological process is heated reducing gas. Reducing potential of the gas is characterized by a volumetric share of components (CO+H 2 )-RC in relation to volume of whole mix of gases received with gasification of coal. The value of parameter RC is regulated by a degree of enrichment of air by oxygen r 0 , and the temperature - by the charge of a parity of endothermic reaction in the chamber of gas regeneration. The dependence of the gas structure and temperature on the degree of enrichment of air by oxygen is shown and the circuit of the gas generator is given. (author)

  5. Cryogenic filter method produces super-pure helium and helium isotopes

    Hildebrandt, A. F.

    1964-01-01

    Helium is purified when cooled in a low pressure environment until it becomes superfluid. The liquid helium is then filtered through iron oxide particles. Heating, cooling and filtering processes continue until the purified liquid helium is heated to a gas.

  6. Experimental and numerical study on transient heat transfer for helium gas flowing over a twisted plate with different length

    Wang, Li; Liu, Qiusheng; Fukuda, Katsuya

    2015-01-01

    This study was conducted to investigate the transient heat transfer process between the solid surface and the coolant (helium gas) in Very High Temperature Reactor (VHTR). Forced convection transient heat transfer for helium gas flowing over a twisted plate with different length was experimentally and theoretically studied. The heat generation rate of the twisted plate was increased with a function of Q = Q_0exp(t/τ)(where t is time, τ is period). Experiment was carried out at various periods ranged from 35 ms to 14 s and gas temperature of 303 K under 500 kPa. The flow velocities ranged from 4 m/s to 10 m/s. Platinum plates with a thickness of 0.1 mm and width of 4 mm were used as the test heaters. The plates were twisted with the same helical pitch of 20 mm, and length of 26.8 mm, 67.8 mm and 106.4 mm (pitch numbers of 1, 3 and 5), respectively. Based on the experimental data, it was found that the average heat transfer coefficient approaches the quasi-steady-state value when the dimensionless period τ* (τ* = τU/L, U is flow velocity, and L is effective length) is larger than about 100 and it becomes higher when τ* is small. The heat transfer coefficient decreases with the increase of twisted plate length under the same period of heat generation rate. According to the experimental data, the distribution for heat transfer coefficient along the heater is nonlinear. Numerical simulation results were obtained for average surface temperature difference, heat flux and heat transfer coefficient of the twisted plates with different length and showed reasonable agreement with experimental data. Based on the numerical simulation, mechanism of local heat transfer coefficient distribution was clarified. (author)

  7. Development of Liposomal Bubbles with Perfluoropropane Gas as Gene Delivery Carriers

    Maruyama, Kazuo; Suzuki, Ryo; Sawamura, Kaori; Takizawa, Tomoko; Utoguchi, Naoki; Negishi, Yoichi

    2007-05-01

    Liposomes have some advantages as drug, antigen and gene delivery carriers. Their size can be easily controlled and they can be modified to add a targeting function. Based on liposome technology, we developed novel liposomal bubbles (Bubble liposomes) containing the ultrasound imaging gas, perfluoropropane. We assessed the feasibility of Bubble liposomes as carriers for gene delivery after cavitation induced by ultrasound. At first, we investigated their ability to deliver genes with Bubble liposomes and ultrasound to various types of cells such as mouse sarcoma cells, mouse melanoma cells, human T cell line and human umbilical vein endothelial cells. The results showed that the Bubble liposomes could deliver plasmid DNA to many cell types without cytotoxicity. In addition, we found that Bubble liposomes could effectively deliver plasmid DNA into mouse femoral artery in vivo. The gene transduction with Bubble liposomes was more effectively than conventional lipofection. We conclude that Bubble liposomes are unique and efficient gene delivery carriers in vitro and in vivo.

  8. Optically pumped alkali laser and amplifier using helium-3 buffer gas

    Beach, Raymond J.; Page, Ralph; Soules, Thomas; Stappaerts, Eddy; Wu, Sheldon Shao Quan

    2010-09-28

    In one embodiment, a laser oscillator is provided comprising an optical cavity, the optical cavity including a gain medium including an alkali vapor and a buffer gas, the buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Additionally, an optical excitation source is provided. Furthermore, the laser oscillator is capable of outputting radiation at a first frequency. In another embodiment, an apparatus is provided comprising a gain medium including an alkali vapor and a buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Other embodiments are also disclosed.

  9. Gas-cooled fast-breeder reactor. Helium Circulator Test Facility updated design cost estimate

    1979-04-01

    Costs which are included in the cost estimate are: Titles I, II, and III Architect-Engineering Services; Titles I, II, and III General Atomic Services; site clearing, grading, and excavation; bulk materials and labor of installation; mechanical and electrical equipment with installation; allowance for contractors' overhead, profit, and insurance; escalation on materials and labor; a contingency; and installation of GAC supplied equipment and materials. The total estimated cost of the facility in As Spent Dollars is $27,700,000. Also included is a cost comparison of the updated design and the previous conceptual design. There would be a considerable penalty for the direct-cooled system over the indirect-cooled system due to the excessive cost of the large diameter helium loop piping to an outdoor heat exchanger. The indirect cooled system which utilizes a helium/Dowtherm G heat exchanger and correspondingly smaller and lower pressure piping to its outdoor air cooler proved to be the more economical of the two systems

  10. Deuterium to helium plasma-wall change-over experiments in the JET MkII-gas box divertor

    Hillis, D.L.; Loarer, T.; Bucalossi, J.; Pospieszczyk, A.; Fundamenski, W.; Matthews, G.; Meigs, A.; Morgan, P.; Phillips, V.; Pitts, R.; Stamp, M.; Hellermann, M. von

    2003-01-01

    The deuterium and helium dynamics in the plasma and subdivertor regions of JET are compared during a sequence of similar ohmic and ICRH pulses where 100% He gas is injected into the JET vacuum vessel, whose graphite walls were previously saturated with deuterium. After the first six He fueled change-over discharges, only He plasma operation was performed. Following this investigation, the situation is reversed and the change-over from an initially saturated He wall is investigated when only D 2 plasma fuelling is used. The He concentration is measured in the subdivertor with a species selective Penning gauge. Comparison of the time dependence of the divertor concentrations with those at the edge and strike point shows significant differences during the first six discharges. This difference along with a global He particle balance is used to assess the status of the wall saturation over the initial 6-7 He change-over discharges

  11. Optimization of the gas turbine-modular helium reactor using statistical methods to maximize performance without compromising system design margins

    Lommers, L.J.; Parme, L.L.; Shenoy, A.S.

    1995-07-01

    This paper describes a statistical approach for determining the impact of system performance and design uncertainties on power plant performance. The objectives of this design approach are to ensure that adequate margin is provided, that excess margin is minimized, and that full advantage can be taken of unconsumed margin. It is applicable to any thermal system in which these factors are important. The method is demonstrated using the Gas Turbine Modular Helium Reactor as an example. The quantitative approach described allows the characterization of plant performance and the specification of the system design requirements necessary to achieve the desired performance with high confidence. Performance variations due to design evolution, inservice degradation, and basic performance uncertainties are considered. The impact of all performance variabilities is combined using Monte Carlo analysis to predict the range of expected operation

  12. Mechanical characterization of metallic materials for high-temperature gas-cooled reactors in air and in helium environments

    Sainfort, G.; Cappelaere, M.; Gregoire, J.; Sannier, J.

    1984-01-01

    In the French R and D program for high-temperature gas-cooled reactors (HTGRs), three metallic alloys were studied: steel Chromesco-3 with 2.25% chromium, alloy 800H, and Hastelloy-X. The Chromesco-3 and alloy 800H creep behavior is the same in air and in HTGR atmosphere (helium). The tensile tests of Hastelloy-X specimens reveal that aging has embrittlement and hardening effects up to 700 0 C, but the creep tests at 800 0 C show opposite effects. This particular behavior could be due to induced precipitation by aging and the depletion of hardening elements from the matrix. Tests show a low influence of cobalt content on mechanical properties of Hastelloy-X

  13. Measurements of hydrogen concentration in liquid sodium by using an inert gas carrier method

    Funada, T.; Nihei, I.; Yuhara, S.; Nakasuji, T.

    1979-01-01

    A technique was developed to measure the hydrogen level in liquid sodium using an inert gas carrier method. Hydrogen was extracted into an inert gas from sodium through a thin nickel membrane in the form of a helically wound tube. The amount of hydrogen in the inert gas was analyzed by gas chromatography. The present method is unique in that it can be used over the wide range of sodium temperatures (150 to 700 0 C) and has no problems associated with vacuum systems. The partial pressure of hydrogen in sodium was determined as a function of cold-trap temperature (T/sub c/). Sieverts' constant (K/sub s/) was determined as a function of sodium temperature (T). From Sieverts' constant, the solubility of hydrogen in sodium is calculated. It was found that other impurities in sodium, such as (O) and (OH), have little effect on the hydrogen pressure in the sodium loop

  14. Theoretical and experimental studies on transient heat transfer for forced convection flow of helium gas over a horizontal cylinder

    Liu Qiusheng; Katsuya Fukuda; Zhang Zheng

    2005-01-01

    Forced convection transient heat transfer for helium gas at various periods of exponential increase of heat input to a horizontal cylinder (heater) was theoretically and experimentally studied. In the theoretical study, transient heat transfer was numerically solved based on a turbulent flow model. It was clarified that the surface superheat and heat flux increase exponentially as the heat generation rate increases with the exponential function. The temperature distribution near the cylinder becomes larger as the surface temperature increases. The values of numerical solution for surface temperature and heat flux agree well with the experimental data for the cylinder diameter of 1 mm. However, the heat flux shows difference from the experimental values for the cylinder diameters of 0.7 mm and 2.0 mm. In the experimental studies, the authors measured heat flux, surface temperature, and transient heat transfer coefficients for forced convection flow of helium gas over horizontal cylinders under wide experimental conditions. The platinum cylinders with diameters of 1.0 mm, 0.7 mm, and 2.0 mm were used as test heaters and heated by electric current with an exponential increase of Q 0exp (t/τ) . The gas flow velocities ranged from 2 to 10 m/s, the gas temperatures ranged from 303 to 353 K, and the periods ranged from 50 ms to 20 s. It was clarified that the heat transfer coefficient approaches the quasi-steady-state one for the period τ longer than about 1 s, and it becomes higher for the period shorter than around 1 s. The transient heat transfer shows less dependence on the gas flowing velocity when the period becomes very shorter. The heat transfer shifts to the quasi-steady-state heat transfer for longer periods and shifts to the transient heat transfer for shorter periods at the same flow velocity. It also approaches the quasi-steady-state one for higher flow velocity at the same period. The transient heat transfer coefficients show significant dependence on

  15. Direct implementation of an axial-flow helium gas turbine tool in a system analysis tool for HTGRs

    Kim, Ji Hwan; No, Hee Cheon; Kim, Hyeun Min; Lim, Hong Sik

    2008-01-01

    This study concerns the development of dynamic models for a high-temperature gas-cooled reactor (HTGR) through direct implementation of a gas turbine analysis code with a transient analysis code. We have developed a streamline curvature analysis code based on the Newton-Raphson numerical application (SANA) to analyze the off-design performance of helium gas turbines under conditions of normal operation. The SANA code performs a detailed two-dimensional analysis by means of throughflow calculation with allowances for losses in axial-flow multistage compressors and turbines. To evaluate the performance in the steady-state and load transient of HTGRs, we developed GAMMA-T by implementing SANA in the transient system code, GAMMA, which is a multidimensional, multicomponent analysis tool for HTGRs. The reactor, heat exchangers, and connecting pipes were designed with a one-dimensional thermal-hydraulic model that uses the GAMMA code. We assessed GAMMA-T by comparing its results with the steady-state results of the GTHTR300 of JAEA. We concluded that the results are in good agreement, including the results of the vessel cooling bypass flow and the turbine cooling flow

  16. High-resolution thermal expansion measurements under helium-gas pressure

    Manna, Rudra Sekhar; Wolf, Bernd; de Souza, Mariano; Lang, Michael

    2012-08-01

    We report on the realization of a capacitive dilatometer, designed for high-resolution measurements of length changes of a material for temperatures 1.4 K ⩽ T ⩽ 300 K and hydrostatic pressure P ⩽ 250 MPa. Helium (4He) is used as a pressure-transmitting medium, ensuring hydrostatic-pressure conditions. Special emphasis has been given to guarantee, to a good approximation, constant-pressure conditions during temperature sweeps. The performance of the dilatometer is demonstrated by measurements of the coefficient of thermal expansion at pressures P ≃ 0.1 MPa (ambient pressure) and 104 MPa on a single crystal of azurite, Cu3(CO3)2(OH)2, a quasi-one-dimensional spin S = 1/2 Heisenberg antiferromagnet. The results indicate a strong effect of pressure on the magnetic interactions in this system.

  17. Liquid to gas leak ratios with liquid nitrogen and liquid helium

    Batzer, T.H.; Call, W.R.

    1985-01-01

    To predict the leak rates of liquid helium and liquid nitrogen containers at operating conditions we need to know how small leaks (10 -8 to 10 -5 atm-cm 3 air/s), measured at standard conditions, behave when flooded with these cryogens. Two small leaks were measured at ambient conditions (approx.750 Torr and 295 K), at the normal boiling points of LN 2 and LHe, and at elevated pressures above the liquids. The ratios of the leak rates of the liquids at ambient pressure to the gases (G) at ambient pressure and room temperature were: GN 2 (1), LN 2 (18), GHe(1), and LHe(172). The leak rate ratio of LN 2 at elevated pressure was linear with pressure. The leak rate ratio of LHe at elevated pressure was also linear with pressure

  18. Liquid to gas leak ratios with liquid nitrogen and liquid helium

    Batzer, T.H.; Call, W.R.

    1985-01-01

    To predict the leak rates of liquid helium and liquid nitrogen containers at operating conditions we need to know how small leaks (10 -8 to 10 -5 atm-cm 3 air/s), measured at standard conditions, behave when flooded with these cryogens. Two small leaks were measured at ambient conditions (about 750 Torr and 295 K), at the normal boiling points of LN 2 and LHe, and at elevated pressures above the liquids. The ratios of the leak rates of the liquids at ambient pressure to the gases at ambient pressure and room temperature are presented. The leak rate ratio of LN 2 at elevated pressure was linear with pressure. The leak rate ratio of LHe at elevated pressure was also linear with pressure

  19. A study on purification of Kr and Xe from He carrier gas in HTGR by fixed bed adsorption%吸附法净化高温气冷堆He载气中Kr、Xe的研究

    廖翠萍; 郑振宏; 施福恩; 周大森

    2001-01-01

    用椰子壳活性炭吸附剂固定床吸附法去除高温气冷堆He载气中Kr、Xe杂质。获得了Kr、Xe在椰子壳活性炭上的动吸附规律。考察了吸附温度、浓度、流速及床高等因素对保护作用时间、完全饱和时间、吸附容量的影响,获得最佳运行参数。结果表明:采用椰子壳活性炭可以除去高温气冷堆He载气中Kr、Xe等有害杂质,满足净化系统的要求。%The purification of krypton and xenon from the helium carrier gas of high temperature gas-cooled reactor by fixed bed activate carbon adsorption is studied.Experimental data at different adsorptive temperature,concentration,flow rate and bed depth are obtained from isothermal adsorption tests in order to examine the effects of these parameters on adsorption dynamic and for the optimal parameters selection of adsorption process.The results show that krypton and xenon from the helium carrier gas in HTGR can be eliminated by the coconut putamina activated carbon to meet the demands of purification system.

  20. Leakage analysis of fuel gas pipe in large LNG carrier engine room

    CEN Zhuolun

    2017-10-01

    Full Text Available [Objectives] The electric propulsion dual-fuel engine is becoming dominant in newly built Liquefied Natural Gas(LNGcarriers. To avoid the potential risks that accompany the use of flammable and explosive boil-off gas,the performance of precise safety and reliability assessments is indispensable. [Methods] This research concerns the engine rooms of large LNG carriers which are propelled electrically by a dual-fuel engine. Possible fuel gas(natural gasleak cases in different areas of the engine room are simulated and analyzed. Five representative leak cases defined by leak form,leak location and leak rate are entered into a Computational Fluid Dynamics(CFDsimulation,in which the Reynolds stress model of Fluent software is adopted as the turbulence model. The results of the leaked gas distribution and ventilation velocity field are analyzed in combination to obtain the diffusion tendency and concentration distribution of leaked gas in different areas.[Results] Based on an analysis of the results,an optimized arrangement of flammable gas detectors is provided for the engine room, and the adoption of an explosion-proof exhaust fan is proven to be unnecessary.[Conclusions] These analysis methods can provide a reference for similar gas leakage scenarios occurring in confined ventilated spaces. In addition, the simulation results can be used to quantitatively assess potential fire or explosion damage in order to guide the design of structural reinforcements.

  1. Effect of carrier gas pressure on condensation in a supersonic nozzle

    Wyslouzil, B.E.; Wilemski, G.; Beals, M.G.; Frish, M.B.

    1994-01-01

    Supersonic nozzle experiments were performed with a fixed water or ethanol vapor pressure and varying amounts of nitrogen to test the hypothesis that carrier gas pressure affects the onset of condensation. Such an effect might occur if nonisothermal nucleation were important under conditions of excess carrier gas in the atmospheric pressure range, as has been suggested by Ford and Clement [J. Phys. A 22, 4007 (1989)]. Although a small increase was observed in the condensation onset temperature as the stagnation pressure was reduced from 3 to 0.5 atm, these changes cannot be attributed to any nonisothermal effects. The pulsed nozzle experiments also exhibited two interesting anomalies: (1) the density profiles for the water and ethanol mixtures were shifted in opposite directions from the dry N 2 profile; (2) a long transient period was required before the nozzle showed good pulse-to-pulse repeatability for condensible vapor mixtures. To theoretically simulate the observed onset behavior, calculations of nucleation and droplet growth in the nozzle were performed that took into account two principal effects of varying the carrier gas pressure: (1) the change in nozzle shape due to boundary layer effects and (2) the variation in the heat capacity of the flowing gas. Energy transfer limitations were neglected in calculating the nucleation rates. The trend of the calculated results matched that of the experimental results very well. Thus, heat capacity and boundary layer effects are sufficient to explain the experimental onset behavior without invoking energy transfer limited nucleation. The conclusions about the rate of nucleation are consistent with those obtained recently using an expansion cloud chamber, but are at odds with results from thermal diffusion cloud chamber measurements

  2. A liquid helium saver

    Avenel, O.; Der Nigohossian, G.; Roubeau, P.

    1976-01-01

    A cryostat equipped with a 'liquid helium saver' is described. A mass flow rate M of helium gas at high pressure is injected in a counter-flow heat exchanger extending from room to liquid helium temperature. After isenthalpic expansion through a calibrated flow impedance this helium gas returns via the low pressure side of the heat exchanger. The helium boil-off of the cryostat represents a mass flow rate m, which provides additional precooling of the incoming helium gas. Two operating regimes appear possible giving nearly the same efficiency: (1) high pressure (20 to 25 atm) and minimum flow (M . L/W approximately = 1.5) which would be used in an open circuit with helium taken from a high pressure cylinder; and (2) low pressure (approximately = 3 atm), high flow (M . L/W > 10) which would be used in a closed circuit with a rubber diaphragm pumping-compressing unit; both provide a minimum theoretical boil-off factor of about 8%. Experimental results are reported. (U.K.)

  3. Corrosion of high temperature alloys in the primary circuit helium of high temperature gas cooled reactors. Pt. 2

    Quadakkers, W.J.

    1985-01-01

    The reactive impurities H 2 O, CO, H 2 and CH 4 which are present in the primary coolant helium of high temperature gas-cooled reactors can cause scale formation, internal oxidation and carburization or decarburization of the high temperature structural alloys. In Part 1 of this contribution a theoretical model was presented, which allows the explanation and prediction of the observed corrosion effects. The model is based on a classical stability diagram for chromium, modified to account for deviations from equilibrium conditions caused by kinetic factors. In this paper it is shown how a stability diagram for a commercial alloy can be constructed and how this can be used to correlate the corrosion results with the main experimental parameters, temperature, gas and alloy composition. Using the theoretical model and the presented experimental results, conditions are derived under which a protective chromia based surface scale will be formed which prevents a rapid transfer of carbon between alloy and gas atmosphere. It is shown that this protective surface oxide can only be formed if the carbon monoxide pressure in the gas exceeds a critical value. Psub(CO), which depends on temperature and alloy composition. Additions of methane only have a limited effect provided that the methane/water ratio is not near to, or greater than, a critical value of around 100/1. The influence of minor alloying additions of strong oxide forming elements, commonly present in high temperature alloys, on the protective properties of the chromia surface scales and the kinetics of carbon transfer is illustrated. (orig.) [de

  4. Gas erosion of impeller housing in the operation of a high-temperature, high-pressure helium circulator

    Sanders, J.P.; Heestand, R.L.; Young, H.C.

    1987-01-01

    Three gas-bearing circulators are installed in series in a high-pressure, high-temperature loop to provide helium flow up to 0.47 m 3 /s at a total head of 78 kJ/kg. The design pressure is 10.7 MPa, and temperatures of 1000 0 C can be obtained in the test section. The inlet temperature to the circulators is limited to 450 0 C. During a routine examination of the circulator, deep V-shaped grooves were found in the stationary surface of this cavity. At the same time, a very fine, dark particulate was observed in crevices of the housing. At first it was assumed that the grooves were formed by particulate erosion; however, examination of the grooves and discussions with persons experienced with large circulator operation changed this opinion. Erosion caused by particulate is characteristically rounded on the bottom and has a greater width to depth aspect than the V-shaped grooves, which were observed. Analysis of the particulate indicated that it was essentially the material of the housing that had undergone reactions with impurities in the circulating gas. It was subsequently concluded that the impeller housing had not been heat treated in a sufficiently oxidizing atmosphere after machining to form an adherent oxide coating. This suboxide coating was eroded by the shear forces in the gas. The exposed layer of metal was then further oxidized by the impurities in the gas, and these layers of oxide were successively eroded to produce the grooves. This erosion problem was eliminated by machining a ring of the same material, heat treating it to form an adherent stable oxide, and bolting it in place in the cavity

  5. Flow characteristics of helium gas going through a 90°elbow for flow measurement

    Feng Beibei; Wang Shiming; Yang Xingtuan; Jiang Shengyao

    2014-01-01

    Numerical simulation is performed to investigate the pressure distribution of He-gas under high pressure and high temperature for 10MW High Temperature Gas-cooled Reactor (HTGR-10). Experimental measurements of wall pressure through a self-built test system are carried out to validate the credibility of the computational approach. We present a study for complex flow structure of He-gas using the case of an structurally 90°elbow that is reconstructed from the steam generator of HTGR-10. Pressure measurement of inner wall and outer wall is used to compare with the numerical results. Distribution of wall pressure of He-gas flowing through 90° elbow based on the numerical and experimental approaches show good agreement. Wall pressure distribution of eight cross sections of the elbow is given in detail to represent the entire region of elbow. (author)

  6. [Gas chromatography with a Pulsed discharge helium ionization detector for measurement of molecular hydrogen(H2) in the atmosphere].

    Luan, Tian; Fang, Shuang-xi; Zhou, Ling-xi; Wang, Hong-yang; Zhang, Gen

    2015-01-01

    A high precision GC system with a pulsed discharge helium ionization detector was set up based on the commercial Agilent 7890A gas chromatography. The gas is identified by retention time and the concentration is calculated through the peak height. Detection limit of the system is about 1 x 10(-9) (mole fraction, the same as below). The standard deviation of 140 continuous injections with a standard cylinder( concentration is roughly 600 x 10(-9)) is better than 0.3 x 10(-9). Between 409.30 x 10(-9) and 867.74 x 10(-9) molecular hydrogen mole fractions and peak height have good linear response. By using two standards to quantify the air sample, the precision meets the background molecular hydrogen compatibility goal within the World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) program. Atmospheric molecular hydrogen concentration at Guangzhou urban area was preliminarily measured by this method from January to November 2013. The results show that the atmospheric molecular hydrogen mole fraction varies from 450 x 10(-9) to 700 x 10(-9) during the observation period, with the lowest value at 14:00 (Beijing time, the same as below) and the peak value at 20:00. The seasonal variation of atmospheric hydrogen at Guangzhou area was similar with that of the same latitude stations in northern hemisphere.

  7. Design of multi-input multi-output controller for magnetic bearing which suspends helium gas-turbine generator rotor for high temperature gas cooled reactor

    Takada, Shoji; Funatake, Yoshio; Inagaki, Yoshiyuki

    2009-01-01

    A design of a MIMO controller, which links magnetic forces of multiple magnetic bearings by feedback of multiple measurement values of vibration of a rotor, was proposed for the radial magnetic bearings for the generator rotor of helium gas turbine with a power output of 300 MWe. The generator rotor is a flexible rotor, which passes over the forth critical speed. A controller transfer function was derived at the forth critical speed, in which the bending vibration mode is similar to the one which is excited by unbalance mass to reduce a modeling error. A 1404-dimensional un-symmetric coefficient matrix of equation of state for the rotating rotor affected by Jayro effect was reduced by a modal decomposition using Schur decomposition to reduce a reduction error. The numerical results showed that unbalance response of rotor was 53 and 80 μm p-p , respectively, well below the allowable limits both at the rated and critical speeds. (author)

  8. Use of nonlocal helium microplasma for gas impurities detection by the collisional electron spectroscopy method

    Kudryavtsev, Anatoly A., E-mail: akud@ak2138.spb.edu [St. Petersburg State University, 7-9 Universitetskaya nab., 199034 St. Petersburg (Russian Federation); Stefanova, Margarita S.; Pramatarov, Petko M. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria)

    2015-10-15

    The collisional electron spectroscopy (CES) method, which lays the ground for a new field for analytical detection of gas impurities at high pressures, has been verified. The CES method enables the identification of gas impurities in the collisional mode of electron movement, where the advantages of nonlocal formation of the electron energy distribution function (EEDF) are fulfilled. Important features of dc negative glow microplasma and probe method for plasma diagnostics are applied. A new microplasma gas analyzer design is proposed. Admixtures of 0.2% Ar, 0.6% Kr, 0.1% N{sub 2}, and 0.05% CO{sub 2} are used as examples of atomic and molecular impurities to prove the possibility for detecting and identifying their presence in high pressure He plasma (50–250 Torr). The identification of the particles under analysis is made from the measurements of the high energy part of the EEDF, where maxima appear, resulting from the characteristic electrons released in Penning reactions of He metastable atoms with impurity particles. Considerable progress in the development of a novel miniature gas analyzer for chemical sensing in gas phase environments has been made.

  9. Gas erosion of impeller housing in the operation of a high-temperature, high-pressure helium circulator

    Sanders, J.P.; Heestand, R.L.; Young, H.C.

    1988-01-01

    Three gas-bearing circulators are installed in series in a high-pressure, high-temperature loop to provide helium flow up to 0.47 m 3 /s at a total head of 78 kJ/kg. The design pressure is 10.7 MPa, and temperatures of 1000 deg. C can be obtained in the test section. The inlet temperature to the circulators is limited to 450 deg. C. The 200-kW motor for each circulator is enclosed in the pressure boundary, and the motor is cooled by circulating the gas within the cavity over a water-cooled coil. The full operating speed is 23,500 rpm. A full-flow filter, absolute for particulate above 10 μm, is installed upstream of the circulator to protect the gas bearing surfaces. The minimum clearances between these surfaces during operation are in the range of 15 to 30 μm. During a routine examination of the circulator, deep V-shaped grooves were found in the stationary surface of this cavity. At the same time, a very fine, dark particulate was observed in crevices of the housing. At first it was assumed that the grooves were formed by particulate erosion; however, examination of the grooves and discussions with persons experienced with large circulator operation changed this opinion. Erosion caused by particulate is characteristically rounded on the bottom and has a greater width to depth aspect than the V-shaped grooves, which were observed. Analysis of the particulate indicated that it was essentially the material of the housing that had undergone reactions with impurities in the circulating gas. It was subsequently concluded that the impeller housing had not been heat treated in a sufficiently oxidizing atmosphere after machining to form an adherent oxide coating. This suboxide coating was eroded by the shear forces in the gas. The exposed layer of metal was then further oxidized by the impurities in the gas, and these layers of oxide were successively eroded to produce the grooves. This erosion problem was eliminated by machining a ring of the same material, heat

  10. Interactions of reactor helium and simulating gas mixtures with high-temperature metals with particular regard to simultaneous deformation

    Berchtold, L.

    1983-01-01

    For the observation of multicomponent alloys (Inconel 617 and 713LC, chroman (Ni20Cr), vacromium (Ni20Cr+Si), TZM) in multicomponent HTR atmospheres (HHT search gas), interaction between gases and metals was studied, both in theoretical descriptions and experimentally. From the experimental viewpoint, gradual simplification employs, on the one hand, tests effected in undiluted atmospheres with exclusively oxidizing or carburizing properties; on the other hand, more simple alloys and pure metals are applied specifically in the helium atmosphere. For an evaluation of the materials, it is maintained that in a strongly oxidizing (H 2 O-rich) atmosphere, e.g. in HHT search gas, materials with sufficient chrome content (e.g. 20% Cr in Ni alloys such as IN 617) offer favourable conditions for an almost complete interruption of carburizing reactions. In that case, the maintenance of the shielding effect of coating during rapid deformation and a tendency to planar delamination during deformation, which becomes stronger as the layer thickness increases, appear to be critical. Concentrations of oxide-forming agents stronger than chromium offer disadvantages rather than advantages. Owing to its tendency to flake off as the covering oxide SiO 2 or as part of a cover layer, silicon may more than destroy the light advantage of a slowed down process of carbon diffusion. The cast alloy IN 713LC shows a deep-reaching carburation in HHT search gas, both with and without deformation. No deep-reaching corrosive damage is noticeable on the molybdenum alloy TZM. (orig./MM) [de

  11. Helium the disappearing element

    Sears, Wheeler M

    2015-01-01

    The subject of the book is helium, the element, and its use in myriad applications including MRI machines, particle accelerators, space telescopes, and of course balloons and blimps. It was at the birth of our Universe, or the Big Bang, where the majority of cosmic helium was created; and stellar helium production continues. Although helium is the second most abundant element in the Universe, it is actually quite rare here on Earth and only exists because of radioactive elements deep within the Earth. This book includes a detailed history of the discovery of helium, of the commercial industry built around it, how the helium we actually encounter is produced within the Earth, and the state of the helium industry today. The gas that most people associate with birthday party balloons is running out. “Who cares?” you might ask. Well, without helium, MRI machines could not function, rockets could not go into space, particle accelerators such as those used by CERN could not operate, fiber optic cables would not...

  12. Process for measuring the helium residual gas pressure and circuit for carrying out the process

    Schmidt, C.; Cesnak, L.

    1983-01-01

    In cryotechnic devices, the quality of the thermal insulation can be monitored by checking the pressure of the residual gas. A process is proposed in which a thin super-conducting wire or a superconducting layer acting as vacuum sensor has a heating pulse reaching the critical current applied to it, which produces a local normal conduction zone. The vacuum sensor has a measuring current of constant amount applied to it, which causes a voltage drop on its resistance during the time in which the normal conduction zone exists, the cooling time. The pressure of the residual gas is a function of the integral of the voltage drop and is measured by integrating the voltage during the cooling time. (orig./HP) [de

  13. Effect of carrier gas composition on transferred arc metal nanoparticle synthesis

    Stein, Matthias; Kiesler, Dennis; Kruis, Frank Einar

    2013-01-01

    Metal nanoparticles are used in a great number of applications; an effective and economical production scaling-up is hence desirable. A simple and cost-effective transferred arc process is developed, which produces pure metal (Zn, Cu, and Ag) nanoparticles with high production rates, while allowing fast optimization based on energy efficiency. Different carrier gas compositions, as well as the electrode arrangements and the power input are investigated to improve the production and its efficiency and to understand the arc production behavior. The production rates are determined by a novel process monitoring method, which combines an online microbalance method with a scanning mobility particle sizer for fast production rate and size distribution measurement. Particle characterization is performed via scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction measurements. It is found that the carrier gas composition has the largest impact on the particle production rate and can increase it with orders of magnitude. This appears to be not only a result of the increased heat flux and melt temperature but also of the formation of tiny nitrogen (hydrogen) bubbles in the molten feedstock, which impacts feedstock evaporation significantly in bi-atomic gases. A production rate of sub 200 nm particles from 20 up to 2,500 mg/h has been realized for the different metals. In this production range, specific power consumptions as low as 0.08 kWh/g have been reached.

  14. A heat exchanger between forced flow helium gas at 14 to 18 K and liquid hydrogen at 20 K circulated by natural convection

    Green, M.A.; Ishimoto, S.; Lau, W.; Yang, S.

    2003-01-01

    The Muon Ionization Cooling Experiment (MICE) has three 350-mm long liquid hydrogen absorbers to reduce the momentum of 200 MeV muons in all directions. The muons are then re-accelerated in the longitudinal direction by 200 MHz RF cavities. The result is cooled muons with a reduced emittance. The energy from the muons is taken up by the liquid hydrogen in the absorber. The hydrogen in the MICE absorbers is cooled by natural convection to the walls of the absorber that are in turn cooled by helium gas that enters at 14 K. This report describes the MICE liquid hydrogen absorber and the heat exchanger between the liquid hydrogen and the helium gas that flows through passages in the absorber wall

  15. Gas Flow Validation with Panda Tests from the OECD SETH Benchmark Covering Steam/Air and Steam/Helium/Air Mixtures

    Royl, P.; Travis, J.R.; Breitung, W.; Kim, J.; Kim, S.B.

    2009-01-01

    The CFD code GASFLOW solves the time-dependent compressible Navier-Stokes Equations with multiple gas species. GASFLOW was developed for nonnuclear and nuclear applications. The major nuclear applications of GASFLOW are 3D analyses of steam/hydrogen distributions in complex PWR containment buildings to simulate scenarios of beyond design basis accidents. Validation of GASFLOW has been a continuously ongoing process together with the development of this code. This contribution reports the results from the open posttest GASFLOW calculations that have been performed for new experiments from the OECD SETH Benchmark. Discussed are the steam distribution tests 9 and 9 bis, 21 and 21 bis involving comparable sequences with and without steam condensation and the last SETH test 25 with steam/helium release and condensation. The latter one involves lighter gas mixture sources like they can result in real accidents. The helium is taken as simulant for hydrogen

  16. Critical Current and Stability of MgB$_2$ Twisted-Pair DC Cable Assembly Cooled by Helium Gas

    AUTHOR|(CDS)2069632; Ballarino, Amalia; Yang, Yifeng; Young, Edward Andrew; Bailey, Wendell; Beduz, Carlo

    2013-01-01

    Long length superconducting cables/bus-bars cooled by cryogenic gases such as helium operating over a wider temperature range are a challenging but exciting technical development prospects, with applications ranging from super-grid transmission to future accelerator systems. With limited existing knowledge and previous experiences, the cryogenic stability and quench protection of such cables are crucial research areas because the heat transfer is reduced and temperature gradient increased compared to liquid cryogen cooled cables. V-I measurements on gas-cooled cables over a significant length are an essential step towards a fully cryogenic stabilized cable with adequate quench protection. Prototype twisted-pair cables using high-temperature superconductor and MgB2 tapes have been under development at CERN within the FP7 EuCARD project. Experimental studies have been carried out on a 5-m-long multiple MgB$_2$ cable assembly at different temperatures between 20 and 30 K. The subcables of the assembly showed sim...

  17. Ejecta Particle-Size Measurements in Vacuum and Helium Gas using Ultraviolet In-Line Fraunhofer Holography

    Sorenson, Danny S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pazuchanics, Peter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Johnson, Randall P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Malone, R. M. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Kaufman, M. I. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tibbitts, A. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tunnell, T. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Marks, D. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Capelle, G. A. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Grover, M. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Marshall, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Stevens, G. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Turley, W. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); LaLone, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States)

    2014-06-25

    An Ultraviolet (UV) in-line Fraunhofer holography diagnostic has been developed for making high-resolution spatial measurements of ejecta particles traveling at many mm/μsec. This report will discuss the development of the diagnostic including the high-powered laser system and high-resolution optical relay system. In addition, the system required to reconstruct the images from the hologram and the corresponding analysis of those images to extract particles will also be described. Finally, results from six high-explosive (HE), shock-driven Sn ejecta experiments will be presented. Particle size distributions will be shown that cover most of the ejecta velocities for experiments conducted in a vacuum, and helium gas environments. In addition, a modification has been made to the laser system that produces two laser pulses separated by 6.8 ns. This double-pulsed capability allows a superposition of two holograms to be acquired at two different times, thus allowing ejecta velocities to be measured directly. Results from this double pulsed experiment will be described.

  18. Exergoeconomic assessment and parametric study of a Gas Turbine-Modular Helium Reactor combined with two Organic Rankine Cycles

    Mohammadkhani, F.; Shokati, N.; Mahmoudi, S.M.S.; Yari, M.; Rosen, M.A.

    2014-01-01

    An exergoeconomic analysis is reported for a combined system with a net electrical output of 299 MW in which waste heat from a Gas Turbine-Modular Helium Reactor (GT-MHR) is utilized by two Organic Rankine Cycles (ORCs). A parametric study is also done to reveal the effects on the exergoeconomic performance of the combined system of such significant parameters as compressor pressure ratio, turbine inlet temperature, temperatures of evaporators, pinch point temperature difference in the evaporators and degree of superheat at the ORC (Organic Rankine Cycle) turbines inlet. Finally the combined cycle performance is optimized from the viewpoint of exergoeconomics. The results show that the precooler, the intercooler and the ORC condensers exhibit the worst exergoeconomic performance. For the overall system, the exergoeconomic factor, the capital cost rate and the exergy destruction cost rate are determined to be 37.95%, 6876 $/h and 11,242 $/h, respectively. Also, it is observed that the unit cost of electricity produced by the GT-MHR turbine increases with increasing GT-MHR turbine inlet temperature but decreases as the other above mentioned parameters increase. - Highlights: • An exergoeconomic analysis is performed for the GT-MHR/ORC (Organic Rankine Cycle) combined cycle. • The effects of decision parameters on the exergoeconomic performance are studied. • The highest exergy destructions occur in the precooler, intercooler and condenser. • Superheating the working fluid at the ORC turbine inlet is not necessary. • Thermodynamic and exergoeconomic optimal conditions differ from each other

  19. DEPOSITION OF FISSION PRODUCTS FROM HELIUM GAS FLOWING AT HIGH VELOCITIES

    Abriss, A.; Ewing, R. A.; Sunderman, D. N.

    1963-11-15

    From American Nuclear Society Meeting, New York, Nov. 1963. Out-of- pile experiments simulating gas cooled reactor flow and temperature conditions were made to correlate by both empirical and theoretical considerations such parameters as Reynolds numbers, velocity, surface conditions, materials of construction, geometry, particulate matter, and fission product diffusion coefficients. It was concluded that all regions of flow disturbance are areas of buildup of activity. No selectivity in deposition among the elements studied, with the exception of I, Te, and Cs, was found. Relative abundances to each other of less volatile isotopes remained constant throughout any particular experiment. Data are tabulated. (P.C.H.)

  20. Emission spectra of alkali-metal (K,Na,Li)-He exciplexes in cold helium gas

    Enomoto, K.; Hirano, K.; Kumakura, M.; Takahashi, Y.; Yabuzaki, T.

    2004-01-01

    We have observed emission spectra of excimers and exciplexes composed of a light alkali-metal atom in the first excited state and 4 He atoms [K*He n (n=1-6), Na * He n (n=1-4), and Li * He n (n=1,2)] in cryogenic He gas (the temperature 2 K -1 . Differently from exciplexes with heavier alkali-metal atoms, the spectra for the different number of He atoms were well separated, so that their assignment could be made experimentally. Comparing with the spectra of K * He n , we found that the infrared emission spectrum of the K atom excited in liquid He was from K*He 6 . To confirm the assignment, we have also carried out ab initio calculation of adiabatic potential curves and peak positions of the emission spectra of the exciplexes

  1. Evaluation of effect of inlet distortion on aerodynamic performance of helium gas compressor for gas turbine high temperature reactor (GTHTR300). Contract research

    Takada, Shoji; Takizuka, Takakazu; Yan, Xing; Kurokouchi, Naohiro; Kunitomi, Kazuhiko

    2006-02-01

    Because the main pipe is connected perpendicular to the flow direction inside the distributing header in the inlet casing of the helium gas compressor design of GTHTR300, the main flow flowing into the header tends to separate from the header wall and to cause reverse flow, which increases flow resistance in the header. This phenomenon increases the total pressure loss in the header and inlet distortion, which is considered to deteriorate the aerodynamic performance of the compressor. Tests were carried out to evaluate the effects of inlet distortion on aerodynamic performance of compressor by using a 1/3-scale helium gas compressor model by varying a level of inlet distortion. Flow was injected from the wall of header to make circumferential velocities uniform before and after the reverse flow region to dissipate the separation and reverse flow. At the design point, inlet distortion was reduced by 2-3% by injection, which resulted in increasing adiabatic efficiency of blade section by 0.5%. A modified flow rate at surge point was lowered from 10.0 kg/s to 9.6 kg/s. At the same time, pressure loss of the inlet casing was reduced by 3-5 kPa, which is equivalent to adiabatic efficiency improvement around 0.8%. By setting orifice at the inlet of the inlet casing, the level of inlet distortion became 3% higher and the adiabatic efficiency of blade section became 1% higher at the design point. The modified flow rate at surge point increased from 10.6 to 10.9 kg/s. A new correlation between inlet distortion and adiabatic efficiency of blade section at the rated flow rate was derived based on compressor-in-parallel model and fitted to the test results. An overall adiabatic efficiency of full-scale compressor was predicted 90.2% based on the test results of efficiency and Reynolds number correlation, which was close to 89.7% that was predicted by test calibrated design through-flow code. (author)

  2. Fission signal detection using helium-4 gas fast neutron scintillation detectors

    Lewis, J. M., E-mail: lewisj@ufl.edu; Kelley, R. P.; Jordan, K. A. [Nuclear Engineering Program, University of Florida, Gainesville, Florida 32611 (United States); Murer, D. [Arktis Radiation Detectors Ltd., 8045 Zurich (Switzerland)

    2014-07-07

    We demonstrate the unambiguous detection of the fission neutron signal produced in natural uranium during active neutron interrogation using a deuterium-deuterium fusion neutron generator and a high pressure {sup 4}He gas fast neutron scintillation detector. The energy deposition by individual neutrons is quantified, and energy discrimination is used to differentiate the induced fission neutrons from the mono-energetic interrogation neutrons. The detector can discriminate between different incident neutron energies using pulse height discrimination of the slow scintillation component of the elastic scattering interaction between a neutron and the {sup 4}He atom. Energy histograms resulting from this data show the buildup of a detected fission neutron signal at higher energies. The detector is shown here to detect a unique fission neutron signal from a natural uranium sample during active interrogation with a (d, d) neutron generator. This signal path has a direct application to the detection of shielded nuclear material in cargo and air containers. It allows for continuous interrogation and detection while greatly minimizing the potential for false alarms.

  3. Performance of the gas turbine-modular helium reactor fuelled with different types of fertile TRISO particles

    Talamo, Alberto; Gudowski, Waclaw

    2005-01-01

    Preliminary studies have been performed on operation of the gas turbine-modular helium reactor (GT-MHR) with a thorium based fuel. The major options for a thorium fuel are a mixture with light water reactors spent fuel, mixture with military plutonium or with with fissile isotopes of uranium. Consequently, we assumed three models of the fuel containing a mixture of thorium with 239 Pu, 233 U or 235 U in TRISO particles with a different kernel radius keeping constant the packing fraction at the level of 37.5%, which corresponds to the current compacting process limit. In order to allow thorium to act as a breeder of fissile uranium and ensure conditions for a self-sustaining fission chain, the fresh fuel must contain a certain quantity of fissile isotope at beginning of life; we refer to the initial fissile nuclide as triggering isotope. The small capture cross-section of 232 Th in the thermal neutron energy range, compared to the fission one of the common fissile isotopes ( 239 Pu, 233 U and 235 U), requires a quantity of thorium 25-30 times greater than that one of the triggering isotope in order to equilibrate the reaction rates. At the same time, the amount of the triggering isotope must be enough to set the criticality condition of the reactor. These two conditions must be simultaneously satisfied. The necessity of a large mass of fuel forces to utilize TRISO particles with a large radius of the kernel, 300 μm. Moreover, in order to improve the neutron economics, a fuel cycle based on thorium requires a low capture to fission ratio of the triggering isotope. Amid the common fissile isotopes, 233 U, 235 U and 239 Pu, we have found that only the uranium nuclides have shown to have the suitable neutronic features to enable the GT-MHR to work on a fuel based on thorium

  4. Performance of the gas turbine-modular helium reactor fuelled with different types of fertile TRISO particles

    Talamo, Alberto [Department of Nuclear and Reactor Physics, Royal Institute of Technology, Roslagstullsbacken 21, S-106 91 Stockholm (Sweden)]. E-mail: alby@neutron.kth.se; Gudowski, Waclaw [Department of Nuclear and Reactor Physics, Royal Institute of Technology, Roslagstullsbacken 21, S-106 91 Stockholm (Sweden)

    2005-11-15

    Preliminary studies have been performed on operation of the gas turbine-modular helium reactor (GT-MHR) with a thorium based fuel. The major options for a thorium fuel are a mixture with light water reactors spent fuel, mixture with military plutonium or with with fissile isotopes of uranium. Consequently, we assumed three models of the fuel containing a mixture of thorium with {sup 239}Pu, {sup 233}U or {sup 235}U in TRISO particles with a different kernel radius keeping constant the packing fraction at the level of 37.5%, which corresponds to the current compacting process limit. In order to allow thorium to act as a breeder of fissile uranium and ensure conditions for a self-sustaining fission chain, the fresh fuel must contain a certain quantity of fissile isotope at beginning of life; we refer to the initial fissile nuclide as triggering isotope. The small capture cross-section of {sup 232}Th in the thermal neutron energy range, compared to the fission one of the common fissile isotopes ({sup 239}Pu, {sup 233}U and {sup 235}U), requires a quantity of thorium 25-30 times greater than that one of the triggering isotope in order to equilibrate the reaction rates. At the same time, the amount of the triggering isotope must be enough to set the criticality condition of the reactor. These two conditions must be simultaneously satisfied. The necessity of a large mass of fuel forces to utilize TRISO particles with a large radius of the kernel, 300 {mu}m. Moreover, in order to improve the neutron economics, a fuel cycle based on thorium requires a low capture to fission ratio of the triggering isotope. Amid the common fissile isotopes, {sup 233}U, {sup 235}U and {sup 239}Pu, we have found that only the uranium nuclides have shown to have the suitable neutronic features to enable the GT-MHR to work on a fuel based on thorium.

  5. Managing the reactivity excess of the gas turbine-modular helium reactor by burnable poison and control rods

    Talamo, Alberto

    2006-01-01

    The gas turbine-modular helium reactor coupled to the deep burn in-core fuel management strategy offers the extraordinary capability to incinerate over 50% of the initial inventory of fissile material. This extraordinary feature, coming from an advanced and well tested fuel element design, which takes advantage of the TRISO particles technology, is maintained while the reactor is loaded with the most different types of fuels. In the present work, we assumed the reactor operating at the equilibrium of the fuel composition, obtained by a 6 years irradiation of light water reactor waste, and we investigated the effects of the introduction of the burnable poison and the control rods; we equipped the core with all the three types of control rods: operational, startup and shutdown ones. We employed as burnable poison natural erbium, due to the 167 Er increasing neutron capture microscopic cross-section in the energy range where the neutron spectrum exhibits the thermal peak; in addition, we utilized boron carbide, with 90% enrichment in 1 B, as the absorption material of the control rods. Concerning the burnable poison studies, we focused on the k eff value, the 167 Er mass during burnup, the influence of modifying the radius of the BISO particles kernel and the fuel and moderator coefficients of temperature. Concerning the control rods studies, we investigated the reactivity worth, the changes in the neutron flux profile due to a partial insertion, the influence of modifying the radius of the BISO particles kernel and the β eff , at the beginning of the operation

  6. Managing the reactivity excess of the gas turbine-modular helium reactor by burnable poison and control rods

    Talamo, Alberto [Department of Nuclear and Reactor Physics, Royal Institute of Technology, Roslagstullsbacken 21, S-10691, Stockholm (Sweden)]. E-mail: alby@neutron.kth.se

    2006-01-15

    The gas turbine-modular helium reactor coupled to the deep burn in-core fuel management strategy offers the extraordinary capability to incinerate over 50% of the initial inventory of fissile material. This extraordinary feature, coming from an advanced and well tested fuel element design, which takes advantage of the TRISO particles technology, is maintained while the reactor is loaded with the most different types of fuels. In the present work, we assumed the reactor operating at the equilibrium of the fuel composition, obtained by a 6 years irradiation of light water reactor waste, and we investigated the effects of the introduction of the burnable poison and the control rods; we equipped the core with all the three types of control rods: operational, startup and shutdown ones. We employed as burnable poison natural erbium, due to the {sup 167}Er increasing neutron capture microscopic cross-section in the energy range where the neutron spectrum exhibits the thermal peak; in addition, we utilized boron carbide, with 90% enrichment in {sup 1}B, as the absorption material of the control rods. Concerning the burnable poison studies, we focused on the k {sub eff} value, the {sup 167}Er mass during burnup, the influence of modifying the radius of the BISO particles kernel and the fuel and moderator coefficients of temperature. Concerning the control rods studies, we investigated the reactivity worth, the changes in the neutron flux profile due to a partial insertion, the influence of modifying the radius of the BISO particles kernel and the {beta} {sub eff}, at the beginning of the operation.

  7. Powering of an HTS dipole insert-magnet operated standalone in helium gas between 5 and 85 K

    van Nugteren, J.; Kirby, G.; Bajas, H.; Bajko, M.; Ballarino, A.; Bottura, L.; Chiuchiolo, A.; Contat, P.-A.; Dhallé, M.; Durante, M.; Fazilleau, P.; Fontalva, A.; Gao, P.; Goldacker, W.; ten Kate, H.; Kario, A.; Lahtinen, V.; Lorin, C.; Markelov, A.; Mazet, J.; Molodyk, A.; Murtomäki, J.; Long, N.; Perez, J.; Petrone, C.; Pincot, F.; de Rijk, G.; Rossi, L.; Russenschuck, S.; Ruuskanen, J.; Schmitz, K.; Stenvall, A.; Usoskin, A.; Willering, G.; Yang, Y.

    2018-06-01

    This paper describes the standalone magnet cold testing of the high temperature superconducting (HTS) magnet Feather-M2.1-2. This magnet was constructed within the European funded FP7-EUCARD2 collaboration to test a Roebel type HTS cable, and is one of the first high temperature superconducting dipole magnets in the world. The magnet was operated in forced flow helium gas with temperatures ranging between 5 and 85 K. During the tests a magnetic dipole field of 3.1 T was reached inside the aperture at a current of 6.5 kA and a temperature of 5.7 K. These values are in agreement with the self-field critical current of the used SuperOx cable assembled with Sunam tapes (low-performance batch), thereby confirming that no degradation occurred during winding, impregnation, assembly and cool-down of the magnet. The magnet was quenched many tens of times by ramping over the critical current and no degradation nor training was evident. During the tests the voltage over the coil was monitored in the microvolt range. An inductive cancellation wire was used to remove the inductive component, thereby significantly reducing noise levels. Close to the quench current, drift was detected both in temperature and voltage over the coil. This drifting happens in a time scale of minutes and is a clear indication that the magnet has reached its limit. All quenches happened approximately at the same average electric field and thus none of the quenches occurred unexpectedly.

  8. Combining a gas turbine modular helium reactor and an accelerator and for near total destruction of weapons grade plutonium

    Baxter, A.M.; Lane, R.K.; Sherman, R. [General Atomics, San Diego, CA (United States)

    1995-10-01

    Fissioning surplus weapons-grade plutonium (WG-Pu) in a reactor is an effective means of rendering this stockpile non-weapons useable. In addition the enormous energy content of the plutonium is released by the fission process and can be captured to produce valuable electric power. While no fission option has been identified that can accomplish the destruction of more than about 70% of the WG-Pu without repeated reprocessing and recycling, which presents additional opportunities for diversion, the gas turbine modular helium-cooled reactor (GT-MHR), using an annular graphite core and graphite inner and outer reflectors combines the maximum plutonium destruction and highest electrical production efficiency and economics in an inherently safe system. Accelerator driven sub-critical assemblies have also been proposed for WG-Pu destruction. These systems offer almost complete WG-Pu destruction, but achieve this goal by using circulating aqueous or molten salt solutions of the fuel, with potential safety implications. By combining the GT-MHR with an accelerator-driven sub-critical MHR assembly, the best features of both systems can be merged to achieve the near total destruction of WG-Pu in an inherently safe, diversion-proof system in which the discharged fuel elements are suitable for long term high level waste storage without the need for further processing. More than 90% total plutonium destruction, and more than 99.9% Pu-239 destruction, could be achieved. The modular concept minimizes the size of each unit so that both the GT-MHR and the accelerator would be straightforward extensions of current technology.

  9. Artificial dissipation models applied to Navier-Stokes equations for analysis of supersonic flow of helium gas around a geometric configuration ramp type

    Rocha, Jussie Soares da; Maciel, Edisson Savio de G.; Lira, Carlos A.B. de O.

    2015-01-01

    Very High Temperature Gas Cooled Reactors - VHTGRs are studied by several research groups for the development of advanced reactors that can meet the world's growing energy demand. The analysis of the flow of helium coolant around the various geometries at the core of these reactors through computational fluid dynamics techniques is an essential tool in the development of conceptual designs of nuclear power plants that provide added safety. This analysis suggests a close analogy with aeronautical cases widely studied using computational numerical techniques to solve systems of governing equations for the flow involved. The present work consists in solving the Navier-Stokes equations in a conservative form, in two-dimensional space employing a finite difference formulation for spatial discretization using the Euler method for explicit marching in time. The physical problem of supersonic laminar flow of helium gas along a ramp configuration is considered. For this, the Jameson and Mavriplis algorithm and the artificial dissipations models linear and nonlinear of Pulliam was implemented. A spatially variable time step is employed aiming to accelerate the convergence to the steady state solution. The main purpose of this work is to study the cited dissipation models and describe their characteristics in relation to the overall quality of the solution, aiming preliminary results for the development of computational tools of dynamic analysis of helium flow for the VHTGR core. (author)

  10. Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to–electron mass ratio

    Hori, Masaki; Sótér, Anna; Barna, Daniel; Dax, Andreas; Hayano, Ryugo; Kobayashi, Takumi; Murakami, Yohei; Todoroki, Koichi; Yamada, Hiroyuki; Horváth, Dezső; Venturelli, Luca

    2016-01-01

    Charge, parity, and time reversal (CPT) symmetry implies that a particle and its antiparticle have the same mass. The antiproton-to-electron mass ratio Embedded Image can be precisely determined from the single-photon transition frequencies of antiprotonic helium. We measured 13 such frequencies with laser spectroscopy to a fractional precision of 2.5 × 10−9 to 16 × 10−9. About 2 × 109 antiprotonic helium atoms were cooled to temperatures between 1.5 and 1.7 kelvin by using buffer-gas cooling in cryogenic low-pressure helium gas; the narrow thermal distribution led to the observation of sharp spectral lines of small thermal Doppler width. The deviation between the experimental frequencies and the results of three-body quantum electrodynamics calculations was reduced by a factor of 1.4 to 10 compared with previous single-photon experiments. From this, Embedded Image was determined as 1836.1526734(15), which agrees with a recent proton-to-electron experimental value within 8 × 10−10.

  11. Liquid helium

    Atkins, K R

    1959-01-01

    Originally published in 1959 as part of the Cambridge Monographs on Physics series, this book addresses liquid helium from the dual perspectives of statistical mechanics and hydrodynamics. Atkins looks at both Helium Three and Helium Four, as well as the properties of a combination of the two isotopes. This book will be of value to anyone with an interest in the history of science and the study of one of the universe's most fundamental elements.

  12. Performance analysis of a large-scale helium Brayton cryo-refrigerator with static gas bearing turboexpander

    Zhang, Yu; Li, Qiang; Wu, Jihao; Li, Qing; Lu, Wenhai; Xiong, Lianyou; Liu, Liqiang; Xu, Xiangdong; Sun, Lijia; Sun, Yu; Xie, Xiujuan; Wang, Bingming; Qiu, Yinan; Zhang, Peng

    2015-01-01

    Highlights: • A 2 kW at 20.0 K helium Brayton cryo-refrigerator is built in China. • A series of tests have been systematically conducted to investigate the performance of the cryo-refrigerator. • Maximum heat conductance proportion (90.7%) appears in the heat exchangers of cold box rather than those of heat reservoirs. • A model of helium Brayton cryo-refrigerator/cycle is presented according to finite-time thermodynamics. - Abstract: Large-scale helium cryo-refrigerator is widely used in superconducting systems, nuclear fusion engineering, and scientific researches, etc., however, its energy efficiency is quite low. First, a 2 kW at 20.0 K helium Brayton cryo-refrigerator is built, and a series of tests have been systematically conducted to investigate the performance of the cryo-refrigerator. It is found that maximum heat conductance proportion (90.7%) appears in the heat exchangers of cold box rather than those of heat reservoirs, which is the main characteristic of the helium Brayton cryo-refrigerator/cycle different from the air Brayton refrigerator/cycle. Other three characteristics also lie in the configuration of refrigerant helium bypass, internal purifier and non-linearity of specific heat of helium. Second, a model of helium Brayton cryo-refrigerator/cycle is presented according to finite-time thermodynamics. The assumption named internal purification temperature depth (PTD) is introduced, and the heat capacity rate of whole cycle is divided into three different regions in accordance with the PTD: room temperature region, upper internal purification temperature region and lower one. Analytical expressions of cooling capacity and COP are obtained, and we found that the expressions are piecewise functions. Further, comparison between the model and the experimental results for cooling capacity of the helium cryo-refrigerator shows that error is less than 7.6%. The PTD not only helps to achieve the analytical formulae and indicates the working

  13. Purification by molecular sieve of helium used as inert cover gas in nuclear reactors; Epuration de l'helium de couverture des reacteurs nucleaires par adsorption sur tamis moleculaire

    Rozenberg, J; Kahan, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    A method carried out at fairly low temperatures (between -50 and -80 deg. C) has been studied for the purification of the helium used as cover gas for heavy water in reactors. The use of the 5A molecular sieve has been adopted because of its superiority over other adsorbents in this temperature range. The particular problems connected with adsorption under dynamic conditions have been dealt with separately. The nitrogen adsorption isotherms have been plotted and the heat of adsorption calculated. (authors) [French] Une methode d'epuration, a temperature moderement basse (comprise entre -50 et -80 deg. C) de l'helium servant de couverture inerte a l'eau lourde des reacteurs a ete etudiee. L'emploi au tamis moleculaire 5A a ete retenu pour la superiorite de celui-ci sur d'autres adsorbants dans ce domaine de temperatures. Les problemes particuliers a l'adsorption en regime dynamique ont ete separement traites. Les isothermes d'adsorption d'azote ont ete tracees et la chaleur d'adsorp. tion calculee. (auteurs)

  14. System analysis for HTTR-GT/H2 plant. Safety analysis of HTTR for coupling helium gas turbine and H2 plant

    Sato, Hiroyuki; Yan, Xing L.; Ohashi, Hirofumi

    2017-08-01

    High Temperature Gas-cooled Reactor (HTGR) is expected to extend the use of nuclear heat to a wider spectrum of industrial applications because of the high temperature heat supply capability and inherently safe characteristics. Japan Atomic Energy Agency initiated a nuclear cogeneration demonstration project with helium gas turbine power generation and thermochemical hydrogen production utilizing the High Temperature engineering Test Reactor (HTTR), the first HTGR in Japan. This study carries out safety evaluation for the HTTR gas turbine hydrogen cogeneration test plant (HTTR-GT/H 2 plant). The evaluation was conducted for the events newly identified corresponding to the coupling of helium gas turbine and hydrogen production plant to the HTTR. The results showed that loss of load event does not have impact on temperature of fuel and reactor coolant pressure boundary. In addition, reactor coolant pressure does not exceed the evaluation criteria. Furthermore, it was shown that reactor operation can be maintained against temperature transients induced by abnormal events in hydrogen production plant. (author)

  15. Effect of mixture ratios and nitrogen carrier gas flow rates on the morphology of carbon nanotube structures grown by CVD

    Malgas, GF

    2008-02-01

    Full Text Available This paper reports on the growth of carbon nanotubes (CNTs) by thermal Chemical Vapour Deposition (CVD) and investigates the effects of nitrogen carrier gas flow rates and mixture ratios on the morphology of CNTs on a silicon substrate by vaporizing...

  16. Effect of substrate mis-orientation on GaN thin films grown by MOCVD under different carrier gas condition

    Kim, Seong-Woo; Suzuki, Toshimasa [Nippon Institute of Technology, 4-1 Gakuendai, Miyashiro, Saitama, 345-8501 (Japan); Aida, Hideo [NAMIKI Precision Jewel Co. Ltd., 3-8-22 Shinden, Adachi-ku, Tokyo, 123-8511 (Japan)

    2005-05-01

    We have studied the effect of a slight mis-orientation angle on surface and crystal quality of GaN thin films grown under different carrier gas conditions. Two types of carrier gas conditions were applied to the growth. One was pure H{sub 2} and the other was mixed N{sub 2}/H{sub 2}. As the result, we found dependence of surface and crystal quality of GaN thin films on the substrate mis-orientation angle, and they indicated almost the same tendency under both growth conditions. Therefore, it was confirmed that mis-orientation angle of sapphire substrate was one of the most critical factors for GaN thin films. Then, the effect of the additional N{sub 2} into the conventional H{sub 2} carrier gas was studied, and we found that the conversion of carrier gas from the conventional H{sub 2} to N{sub 2}/H{sub 2} mixture was effective against degradation of GaN crystallinity at any mis-orientation angle. Considering that the crystal quality of GaN thin films became insensitive to mis-orientation angle as the condition became more suitable for GaN growth, the optimal substrate mis-orientation angle was consequently decided to be approximately 0.15 from the morphological aspect. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Helium cryogenics

    Van Sciver, Steven W

    2012-01-01

    Twenty five years have elapsed since the original publication of Helium Cryogenics. During this time, a considerable amount of research and development involving helium fluids has been carried out culminating in several large-scale projects. Furthermore, the field has matured through these efforts so that there is now a broad engineering base to assist the development of future projects. Helium Cryogenics, 2nd edition brings these advances in helium cryogenics together in an updated form. As in the original edition, the author's approach is to survey the field of cryogenics with emphasis on helium fluids. This approach is more specialized and fundamental than that contained in other cryogenics books, which treat the associated range of cryogenic fluids. As a result, the level of treatment is more advanced and assumes a certain knowledge of fundamental engineering and physics principles, including some quantum mechanics. The goal throughout the work is to bridge the gap between the physics and engineering aspe...

  18. Creep and fatigue properties of Incoloy 800H in a high-temperature gas-cooled reactor (HTGR) helium environment

    Chow, J.G.Y.; Soo, P.; Epel, L.

    1978-01-01

    A mechanical test program to assess the effects of a simulated HTGR helium environment on the fatigue and creep properties of Incoloy 800H and other primary-circuit metals is described. The emphasis and the objectives of this work are directed toward obtaining information to assess the integrity and safety of an HTGR throughout its service life. The helium test environment selected for study contained 40 μ atm H 2 O, 200 μ atm H 2 , 40 μ atm CO, 10 μ atm CO 2 , and 20 μ atm CH 4 . It is believed that this ''wet'' environment simulates that which could exist in a steam-cycle HTGR containing some leaking steam-generator tubes. A recirculating helium loop operating at about 4 psi in which impurities can be maintained at a constant level, has been constructed to supply the desired environment for fatigue and creep testing

  19. Artificial dissipation models applied to Euler equations for analysis of supersonic flow of helium gas around a geometric configurations ramp and diffusor type

    Rocha, Jussiê S., E-mail: jussie.soares@ifpi.edu.br [Instituto Federal do Piauí (IFPI), Valença, PI (Brazil); Maciel, Edisson Sávio de Góes, E-mail: edissonsavio@yahoo.com.br [Instituto Tecnológico de Aeronáutica (ITA), São José dos Campos, SP (Brazil); Lira, Carlos A.B.O., E-mail: cabol@ufpe.edu.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Sousa, Pedro A.S.; Neto, Raimundo N.C., E-mail: augusto.96pedro@gmail.com, E-mail: r.correia17@hotmail.com [Instituto Federal do Piauí (IFPI), Teresina, PI (Brazil)

    2017-07-01

    Very High Temperature Gas Cooled Reactors - VHTGRs are studied by several research groups for the development of advanced reactors that can meet the world's growing energy demand. The analysis of the flow of helium coolant around the various geometries at the core of these reactors through computational fluid dynamics techniques is an essential tool in the development of conceptual designs of nuclear power plants that provide added security. This analysis suggests a close analogy with aeronautical cases widely studied using computational numerical techniques to solve systems of governing equations for the flow involved. The present work consists in using the DISSIPA2D{sub E}ULER code, to solve the Euler equations in a conservative form, in two-dimensional space employing a finite difference formulation for spatial discretization using the Euler method for explicit marching in time. The physical problem of supersonic flow along a ramp and diffusor configurations is considered. For this, the Jameson and Mavriplis algorithm and the artificial dissipation model linear of Pulliam was implemented. A spatially variable time step is employed aiming to accelerate the convergence to the steady state solution. The main purpose of this work is obtain computational tools for flow analysis through the study the cited dissipation model and describe their characteristics in relation to the overall quality of the solution, as well as obtain preliminary results for the development of computational tools of dynamic analysis of helium gas flow in gas-cooled reactors. (author)

  20. Artificial dissipation models applied to Euler equations for analysis of supersonic flow of helium gas around a geometric configurations ramp and diffusor type

    Rocha, Jussiê S.; Maciel, Edisson Sávio de Góes; Lira, Carlos A.B.O.; Sousa, Pedro A.S.; Neto, Raimundo N.C.

    2017-01-01

    Very High Temperature Gas Cooled Reactors - VHTGRs are studied by several research groups for the development of advanced reactors that can meet the world's growing energy demand. The analysis of the flow of helium coolant around the various geometries at the core of these reactors through computational fluid dynamics techniques is an essential tool in the development of conceptual designs of nuclear power plants that provide added security. This analysis suggests a close analogy with aeronautical cases widely studied using computational numerical techniques to solve systems of governing equations for the flow involved. The present work consists in using the DISSIPA2D E ULER code, to solve the Euler equations in a conservative form, in two-dimensional space employing a finite difference formulation for spatial discretization using the Euler method for explicit marching in time. The physical problem of supersonic flow along a ramp and diffusor configurations is considered. For this, the Jameson and Mavriplis algorithm and the artificial dissipation model linear of Pulliam was implemented. A spatially variable time step is employed aiming to accelerate the convergence to the steady state solution. The main purpose of this work is obtain computational tools for flow analysis through the study the cited dissipation model and describe their characteristics in relation to the overall quality of the solution, as well as obtain preliminary results for the development of computational tools of dynamic analysis of helium gas flow in gas-cooled reactors. (author)

  1. Estimation of the minimum Prandtl number for binary gas mixtures formed with light helium and certain heavier gases: Application to thermoacoustic refrigerators

    Campo, Antonio; Papari, Mohammad M.; Abu-Nada, Eiyad

    2011-01-01

    This paper addresses a detailed procedure for the accurate estimation of low Prandtl numbers of selected binary gas mixtures. In this context, helium (He) is the light primary gas and the heavier secondary gases are nitrogen (N 2 ), oxygen (O 2 ), xenon (Xe), carbon dioxide (CO 2 ), methane (CH 4 ), tetrafluoromethane or carbon tetrafluoride (CF 4 ) and sulfur hexafluoride (SF 6 ). The three thermophysical properties forming the Prandtl number of binary gas mixtures Pr mix are heat capacity at constant pressure C p,mix (thermodynamic property), viscosity η mix (transport property) and thermal conductivity λ mix (transport property), which in general depend on temperature T and molar gas composition w. The precise formulas for the calculation of the trio C p,mix , η mix , and λ mix are gathered from various dependable sources. When the set of computed Pr mix values for the seven binary gas mixtures He + N 2 , He + O 2 , He + Xe, He + CO 2 , He + CH 4 , He + CF 4 , He + SF 6 at atmospheric conditions T = 300 K, p = 1 atm is plotted against the molar gas composition w on the w-domain [0,1], the family of Pr mix (w) curves exhibited distinctive concave shapes. In the curves format, all Pr mix (w) curves initiate with Pr ∼ 0.7 at w = 0 (associated with light primary He). Forthwith, each Pr mix (w) curve descends to a unique minimum and thereafter ascend back to Pr ∼ 0.7 at the terminal point w = 1 (connected to heavier secondary gases). Overall, it was found that among the seven binary gas mixtures tested, the He + Xe gas mixture delivered the absolute minimum Prandtl number Pr mix,min = 0.12 at the optimal molar gas composition w opt = 0.975. - Highlights: →Accurate estimation of low Prandtl numbers for some helium-based binary gas mixtures. →The thermophysical properties of the gases are calculated with precise formulas. →The absolute minimum Prandtl number is delivered by the He + Xe binary gas mixture. →Application to experimental thermoacoustic

  2. Study on the adsorption of H2O and CO2 from the carrier gas of high-temperature gas-cooled reactor

    Liao Cuiping; Zheng Zhenhong; Shi Fuen; Zhou Dasen

    1998-01-01

    The author is focused on the experimental studies of the adsorption of moisture and carbon dioxide from the carrier gas of high-temperature gas-cooled reactor (HTGR). A suitable adsorbent--5A type molecular sieve spherical particles with an average diameter of 3 mm is chosen to purify the carrier gas with impurities of moisture and carbon dioxide. Experimental data at different concentration, flow rate, adsorptive temperature, pressure and bed depth are obtained from isothermal adsorption tests in order to examine the effects of these parameters on adsorption dynamic and for the optimal parameters selection of adsorption process. Experimental breakthrough curves, dynamic single component and multicomponent adsorption curves are obtained. The outlet concentration of H 2 O and CO 2 can reach below 1.0 x 10 -5 , so this purification system can meet the demands of HTGR

  3. The influence of carrier gas flow rate in inverse gas chromatography on the estimation of water vapor adsorption on Nylon-6 micro fiber

    丸井, 正樹; 山本, 直子; 牛腸, ヒロミ; マルイ, マサキ; ヤマモト, ナオコ; ゴチョウ, ヒロミ; MASAKI, MARUI; NAOKO, YAMAMOTO; HIROMI, GOCHO

    2002-01-01

    The adsorption behaviors of water vapor on Nylon-6 micro fiber are measured at 90℃ with inverse gas chromatography, of which the carrier gas flow rates are 10~40ml/min. The values of retention volume decrease when the peak area is on the increase. lt indicates that Nylon-6 micro fiber has strong adsorption of water vapor at low vapor pressure. The adsorption isotherm as a whole is found to be of BET II type with certain number of adsorption sites. The gas flow rate has no effect on the estima...

  4. Spectral radiance of strong lines in positive column mercury discharges with argon carrier gas

    Sansonetti, Craig J; Reader, Joseph

    2006-01-01

    The spectral radiance of the 185 and 254 nm lines in two positive column mercury discharge lamps was measured over a wide range of operating conditions. The lamps had internal diameters of 5 and 23 mm. Argon was used as a carrier gas. The lamps were operated with cold spot temperatures of 20, 40 and 60 0 C. At each of these temperatures, results were obtained for five currents ranging from 20 to 100 mA for the 5 mm lamp and from 200 to 1000 mA for the 23 mm lamp. For each current studied, results were determined for argon pressures ranging from 66.6 to 666 Pa (0.5 to 5.0 Torr) in the 5 mm lamp and 26.6 to 666 Pa (0.2 to 5.0 Torr) in the 23 mm lamp. An argon miniarc was used as the radiometric standard. By calibrating the spectral response of the optical system with a well-characterized mercury pencil lamp, results were obtained for 12 additional Hg lines from 289 to 579 nm. For the 23 mm lamp the electric field in the positive column was measured. For this lamp the radiated power as a percentage of input power was also determined. The results provide an experimental basis for validating computer models of Hg fluorescent lamp discharges

  5. An exergoeconomic assessment of waste heat recovery from a Gas Turbine-Modular Helium Reactor using two transcritical CO_2 cycles

    Wang, Xurong; Dai, Yiping

    2016-01-01

    Highlights: • A Gas Turbine-Modular Helium Reactor is coupled with two transcritical CO_2 cycles. • Exergoeconomic analysis and optimization of the combined cycle was performed. • The energy efficiency of the cogeneration system was enhanced by 7.92% at 850 °C. • The overall exergoeconomic factor of the system could up to 55.2%. - Abstract: A comprehensive study is performed on an energy conversion system which combines a gas turbine-modular helium reactor (GT-MHR) and two transcritical CO_2 cycles (tCO_2). The aim of this study is to assess the energy, exergy and economic behavior of the proposed system, considering five indicators: the energy efficiency, the exergy efficiency, the total exergy destruction cost rate, the overall exergoeconomic factor and the total cost rate. A parametric study is also conducted to evaluate the influence of key decision variables on the GT-MHR/tCO_2 performance. Finally, the combined cycle is optimized to minimize the total cost rate. The results show that the energy efficiency of GT-MHR/tCO_2 cycle is 7.92% higher than that of the simple GT-MHR cycle at 850 °C. The largest exergy destruction rate takes place in the reactor, and after that in the helium turbine and the recuperator. The components in tCO_2 cycles have less exergy destruction. When the optimization is conducted based on the exergoeconomics, the overall exergoeconomic factor, the total cost rate and the total exergy destruction cost rate are 55.2%, 20,752 $/h and 9292 $/h, respectively.

  6. Canada's helium output rising fast

    1966-12-01

    About 12 months from now, International Helium Limited will be almost ready to start up Canada's second helium extraction plant at Mankota, in Saskatchewan's Wood Mountain area about 100 miles southwest of Moose Jaw. Another 80 miles north is Saskatchewan's (and Canada's) first helium plant, operated by Canadian Helium and sitting on a gas deposit at Wilhelm, 9 miles north of Swift Current. It contains almost 2% helium, some COD2U, and the rest nitrogen. One year in production was apparently enough to convince Canadian Helium that the export market (it sells most of its helium in W. Europe) can take a lot more than it's getting. Construction began this summer on an addition to the Swift Current plant that will raise its capacity from 12 to 36MMcf per yr when it goes on stream next spring. Six months later, International Helium's 40 MMcf per yr plant to be located about 4 miles from its 2 Wood Mountain wells will double Canada's helium output again.

  7. Charge state distribution of ^{86}Kr in hydrogen and helium gas charge strippers at 2.7  MeV/nucleon

    H. Kuboki

    2014-12-01

    Full Text Available The charge state distributions of krypton (^{86}Kr with an energy of 2.7  MeV/nucleon were measured using hydrogen (H_{2} and helium (He gas charge strippers. A differential pumping system was constructed to confine H_{2} and He gases to a thickness sufficient for the charge state distributions to attain equilibrium. The mean charge states of ^{86}Kr in H_{2} and He gases attained equilibrium at 25.1 and 23.2, respectively, whereas the mean charge state in N_{2} gas at equilibrium was estimated to be less than 20. The charge distributions are successfully reproduced by the cross sections of ionization and electron capture processes optimized by a fitting procedure.

  8. Diamond-like-carbon nanoparticle production and agglomeration following UV multi-photon excitation of static naphthalene/helium gas mixtures

    Walsh, A. J.; Ruth, A. A., E-mail: a.ruth@ucc.ie [Physics Department and Environmental Research Institute, University College Cork, Cork (Ireland); Tielens, A. G. G. M. [Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333-CA Leiden (Netherlands)

    2016-07-14

    We report the formation of nanoparticles with significant diamond character after UV multi-photon laser excitation of gaseous naphthalene, buffered in static helium gas, at room temperature. The nanoparticles are identified in situ by their absorption and scattering spectra between 400 and 850 nm, which are modeled using Mie theory. Comparisons of the particles’ spectroscopic and optical properties with those of carbonaceous materials indicate a sp{sup 3}/sp{sup 2} hybridization ratio of 8:1 of the particles formed. The particle extinction in the closed static (unstirred) gas-phase system exhibits a complex and quasi-oscillatory time dependence for the duration of up to several hours with periods ranging from seconds to many minutes. The extinction dynamics of the system is based on a combination of transport features and particle interaction, predominantly agglomeration. The relatively long period of agglomeration allows for a unique analysis of the agglomeration process of diamond-like carbon nanoparticles in situ.

  9. Connection experiments with a hollow cathode ion source and a helium gas jet system for on-line isotope separation

    Mazumdar, A.K.; Wagner, H.; Walcher, W.; Lund, T.

    1976-01-01

    A helium jet system was connected to a hollow cathode ion source. Using fission products the efficiencies of the different steps were measured by β-, X-ray and γ-counting while the mass spectrum and the focussing of the extracted ion beam were observed with a small deflecting magnet. Mean transport efficiencies of 50% through the 12 m capillary were obtained and ion source efficiencies in the percent range for several elements. (Auth.)

  10. Neutral interstellar helium parameters based on Ulysses/GAS and IBEX-LO observations: What are the reasons for the differences?

    Katushkina, O. A.; Izmodenov, V. V.; Wood, B. E.; McMullin, D. R.

    2014-01-01

    Recent analysis of the interstellar helium fluxes measured in 2009-2010 at Earth's orbit by the Interstellar Boundary Explorer (IBEX) has suggested that the interstellar velocity (both direction and magnitude) is inconsistent with that derived previously from Ulysses/GAS observations made in the period from 1990 to 2002 at 1.5-5.5 AU from the Sun. Both results are model dependent, and models that were used in the analyses are different. In this paper, we perform an analysis of the Ulysses/GAS and IBEX-Lo data using our state-of-the-art three-dimensional time-dependent kinetic model of interstellar atoms in the heliosphere. For the first time, we analyze Ulysses/GAS data from year 2007, the closest available Ulysses/GAS observations in time to the IBEX observations. We show that the interstellar velocity derived from the Ulysses 2007 data is consistent with previous Ulysses results and does not agree with the velocity derived from IBEX. This conclusion is very robust since, as is shown in the paper, it does not depend on the ionization rates adopted in theoretical models. We conclude that Ulysses data are not consistent with the new local interstellar medium (LISM) velocity vector from IBEX. In contrast, IBEX data, in principle, could be explained with the LISM velocity vector derived from the Ulysses data. This is possible for the models where the interstellar temperature increased from 6300 K to 9000 K. There is a need to perform further studies of possible reasons for the broadening of the helium signal core measured by IBEX, which could be an instrumental effect or could be due to unconsidered physical processes.

  11. Neutral interstellar helium parameters based on Ulysses/GAS and IBEX-LO observations: What are the reasons for the differences?

    Katushkina, O. A.; Izmodenov, V. V. [Space Research Institute, Russian Academy of Sciences, Moscow (Russian Federation); Wood, B. E. [Naval Research Laboratory, Space Science Division, Washington, DC 20375 (United States); McMullin, D. R., E-mail: okat@iki.rssi.ru [Space Systems Research Corporation, Alexandria, VA 22314 (United States)

    2014-07-01

    Recent analysis of the interstellar helium fluxes measured in 2009-2010 at Earth's orbit by the Interstellar Boundary Explorer (IBEX) has suggested that the interstellar velocity (both direction and magnitude) is inconsistent with that derived previously from Ulysses/GAS observations made in the period from 1990 to 2002 at 1.5-5.5 AU from the Sun. Both results are model dependent, and models that were used in the analyses are different. In this paper, we perform an analysis of the Ulysses/GAS and IBEX-Lo data using our state-of-the-art three-dimensional time-dependent kinetic model of interstellar atoms in the heliosphere. For the first time, we analyze Ulysses/GAS data from year 2007, the closest available Ulysses/GAS observations in time to the IBEX observations. We show that the interstellar velocity derived from the Ulysses 2007 data is consistent with previous Ulysses results and does not agree with the velocity derived from IBEX. This conclusion is very robust since, as is shown in the paper, it does not depend on the ionization rates adopted in theoretical models. We conclude that Ulysses data are not consistent with the new local interstellar medium (LISM) velocity vector from IBEX. In contrast, IBEX data, in principle, could be explained with the LISM velocity vector derived from the Ulysses data. This is possible for the models where the interstellar temperature increased from 6300 K to 9000 K. There is a need to perform further studies of possible reasons for the broadening of the helium signal core measured by IBEX, which could be an instrumental effect or could be due to unconsidered physical processes.

  12. Use of natural gas, methanol, and ethanol fuel emulsions as environmentally friendly energy carriers for mobile heat power plants

    Likhanov, V. A.; Lopatin, O. P.

    2017-12-01

    The need for using environmentally friendly energy carriers for mobile heat power plants (HPPs) is grounded. Ecologically friendly sources of energy, such as natural gas as well as renewable methyl and ethyl alcohols, are investigated. In order to develop, determine, and optimize the composition of environmentally friendly energy carriers for an HPP, the latter has been tested when working on diesel fuel (DF), compressed natural gas (CNG), and methanol and ethanol fuel emulsions (MFE, EFE). It has been experimentally established that, for the application of environmentally friendly energy carriers for a 4Ch 11.0/12.5 diesel engine of a mobile fuel and power plant, it is necessary to maintain the following ratio of components when working on CNG: 80% gas and 20% DF primer portion. When working on an alcohol mixture, emulsions of the following composition were used: 25% alcohol (methanol or ethanol), 0.5% detergent-dispersant additive succinimide C-5A, 7% water, and 67.5% DF. When this diesel passed from oil DF to environmentally friendly energy sources, it allowed for the reduction of the content of exhaust gases (EG) (1) when working on CNG with recirculation of exhaust gases (EGR) (recirculation was used to eliminate the increased amount of nitric oxides by using CNG): carbon black by 5.8 times, carbon dioxide by 45.9%, and carbon monoxide by 23.8%; (2) when working on MFE: carbon black by 6.4 times, nitrogen oxides by 29.6%, carbon dioxide by 10.1%, and carbon oxide by 47.6%; (3) when working on EFE: carbon black by 4.8 times; nitrogen oxides by 40.3%, carbon dioxide by 26.6%, and carbon monoxide by 28.6%. The prospects of use of environmentally friendly energy carriers in diesels of mobile HPPs, such as natural gas, ethanol, and methanol, has been determined.

  13. Thermodynamic evaluation of hydrogen production for fuel cells by using bio-ethanol steam reforming: Effect of carrier gas addition

    Hernández, Liliana; Kafarov, Viatcheslav

    Omitting the influence of the addition of carrier gas to the reaction system for hydrogen production by bio-ethanol steam reforming can lead to wrong conclusions, especially when it is going to be made to scale. The effect of carrier gas addition to produce hydrogen using bio-ethanol steam reforming to feed fuel cells was evaluated. Thermodynamic calculations in equilibrium conditions were made, however the analysis derived from them can also be applied to kinetic conditions. These calculations were made by using the Aspen-HYSYS software at atmospheric pressure and different values of temperature, water/ethanol molar ratios, and inert (argon)/(water/ethanol) molar ratios. The addition of inert carrier gas modifies the concentrations of the reaction products in comparison to those obtained without its presence. This behavior occurs because most of the reactions which take place in bio-ethanol steam reforming have a positive difference of moles. This fact enhances the system sensitivity to inert concentration at low and moderated temperatures (<700 °C). At high values of temperature, the inert addition does not influence the composition of the reaction products because of the predominant effect of inverse WGS reaction.

  14. Thermodynamic evaluation of hydrogen production for fuel cells by using bio-ethanol steam reforming: Effect of carrier gas addition

    Hernandez, Liliana; Kafarov, Viatcheslav [Universidad Industrial de Santander, Escuela de Ingenieria Quimica, Bucaramanga 678 (Colombia)

    2009-07-01

    Omitting the influence of the addition of carrier gas to the reaction system for hydrogen production by bio-ethanol steam reforming can lead to wrong conclusions, especially when it is going to be made to scale. The effect of carrier gas addition to produce hydrogen using bio-ethanol steam reforming to feed fuel cells was evaluated. Thermodynamic calculations in equilibrium conditions were made, however the analysis derived from them can also be applied to kinetic conditions. These calculations were made by using the Aspen-HYSYS software at atmospheric pressure and different values of temperature, water/ethanol molar ratios, and inert (argon)/(water/ethanol) molar ratios. The addition of inert carrier gas modifies the concentrations of the reaction products in comparison to those obtained without its presence. This behavior occurs because most of the reactions which take place in bio-ethanol steam reforming have a positive difference of moles. This fact enhances the system sensitivity to inert concentration at low and moderated temperatures (<700 C). At high values of temperature, the inert addition does not influence the composition of the reaction products because of the predominant effect of inverse WGS reaction. (author)

  15. Research on dynamics and experiments about auxiliary bearings for the helium circulator of the 10 MW high temperature gas-cooled reactor

    Zhao, Yulan; Yang, Guojun; Liu, Xingnan; Shi, Zhengang; Zhao, Lei

    2016-01-01

    Highlights: • The research in this paper is based on the AMB helium circulator of HTR-10. • The dynamic rotor performance is analyzed by processing experimental data. • The mechanical bearing without lubrication can be applied in the HTR-10 system. - Abstract: The 10 MW high-temperature gas-cooled reactor (HTR-10) was constructed by the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University. The auxiliary bearing is utilized in this system to meet particular requirements for the reactor. The main role of the auxiliary bearing is to constrain rotor displacements and also to support the rotor when the rotor drops down, which is caused by the active magnetic bearing (AMB) failure. The auxiliary bearing needs to endure huge impact, rapid angular acceleration and thermal shock. On the one hand, complex geometrical constructions and forces applied on the system bring difficulties and restrictions to establish an appropriate model to reveal the actual dynamic process. On the other hand, large volumes of data obtained from experiments show velocities and displacements of the rotor during the rotor drop process and then can indicate the actual dynamic interactions to a great extent. The research in this paper is based on the test rig of the AMB helium circulator of HTR-10. This paper aims to analyze the dynamic performance and contact forces of the rotor by processing experimental data. A measurement to estimate forces developed due to impacts of the rotor and the auxiliary bearings is presented. It is of great significance and provides certain foundation to elaborate the rotor drop process for the AMB helium circulator of HTR-10.

  16. Thermal fluid dynamic behavior of coolant helium gas in a typical reactor VHTGR channel of prismatic core; Comportamento termofluidodinamico do gas refrigerante helio em um canal topico de reator VHTGR de nucleo prismatico

    Belo, Allan Cavalcante

    2016-08-01

    The current studies about the thermal fluid dynamic behavior of the VHTGR core reactors of 4{sup th} generation are commonly developed in 3-D analysis in CFD (computational fluid dynamics), which often requires considerable time and complex mathematical calculations for carrying out these analysis. The purpose of this project is to achieve thermal fluid dynamic analysis of flow of gas helium refrigerant in a typical channel of VHTGR prismatic core reactor evaluating magnitudes of interest such as temperature, pressure and fluid velocity and temperature distribution in the wall of the coolant channel from the development of a computer code in MATLAB considering the flow on one-dimensional channel, thereby significantly reducing the processing time of calculations. The model uses three different references to the physical properties of helium: expressions given by the KTA (German committee of nuclear safety standards), the computational tool REFPROP and a set of constant values for the entire channel. With the use of these three references it is possible to simulate the flow treating the gas both compressible and incompressible. The results showed very close values for the interest quantities and revealed that there are no significant differences in the use of different references used in the project. Another important conclusion to be observed is the independence of helium in the gas compressibility effects on thermal fluid dynamic behavior. The study also indicated that the gas undergoes no severe effects due to high temperature variations in the channel, since this goes in the channel at 914 K and exits at approximately 1263 K, which shows the excellent use of helium as a refrigerant fluid in reactor channels VHTGR. The comparison of results obtained in this work with others in the literature served to confirm the effectiveness of the one-dimensional consideration of method of gas flow in the coolant channel to replace the models made in 3-D for the pressure range

  17. Measurement and control system for cryogenic helium gas bearing turbo-expander experimental platform based on Siemens PLC S7-300

    Li, J.; Xiong, L. Y.; Peng, N.; Dong, B.; Wang, P.; Liu, L. Q.

    2014-01-01

    An experimental platform for cryogenic Helium gas bearing turbo-expanders is established at the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences. This turbo-expander experimental platform is designed for performance testing and experimental research on Helium turbo-expanders with different sizes from the liquid hydrogen temperature to the room temperature region. A measurement and control system based on Siemens PLC S7-300 for this turbo-expander experimental platform is developed. Proper sensors are selected to measure such parameters as temperature, pressure, rotation speed and air flow rate. All the collected data to be processed are transformed and transmitted to S7-300 CPU. Siemens S7-300 series PLC CPU315-2PN/DP is as master station and two sets of ET200M DP remote expand I/O is as slave station. Profibus-DP field communication is established between master station and slave stations. The upper computer Human Machine Interface (HMI) is compiled using Siemens configuration software WinCC V6.2. The upper computer communicates with PLC by means of industrial Ethernet. Centralized monitoring and distributed control is achieved. Experimental results show that this measurement and control system has fulfilled the test requirement for the turbo-expander experimental platform.

  18. Measurement and control system for cryogenic helium gas bearing turbo-expander experimental platform based on Siemens PLC S7-300

    Li, J.; Xiong, L. Y.; Peng, N.; Dong, B.; Liu, L. Q. [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China); Wang, P. [Beijing Sciample Technology Co., Ltd., Beijing, 100190 (China)

    2014-01-29

    An experimental platform for cryogenic Helium gas bearing turbo-expanders is established at the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences. This turbo-expander experimental platform is designed for performance testing and experimental research on Helium turbo-expanders with different sizes from the liquid hydrogen temperature to the room temperature region. A measurement and control system based on Siemens PLC S7-300 for this turbo-expander experimental platform is developed. Proper sensors are selected to measure such parameters as temperature, pressure, rotation speed and air flow rate. All the collected data to be processed are transformed and transmitted to S7-300 CPU. Siemens S7-300 series PLC CPU315-2PN/DP is as master station and two sets of ET200M DP remote expand I/O is as slave station. Profibus-DP field communication is established between master station and slave stations. The upper computer Human Machine Interface (HMI) is compiled using Siemens configuration software WinCC V6.2. The upper computer communicates with PLC by means of industrial Ethernet. Centralized monitoring and distributed control is achieved. Experimental results show that this measurement and control system has fulfilled the test requirement for the turbo-expander experimental platform.

  19. An exergoeconomic investigation of waste heat recovery from the Gas Turbine-Modular Helium Reactor (GT-MHR) employing an ammonia–water power/cooling cycle

    Zare, V.; Mahmoudi, S.M.S.; Yari, M.

    2013-01-01

    A detailed exergoeconomic analysis is performed for a combined cycle in which the waste heat from the Gas Turbine-Modular Helium Reactor (GT-MHR) is recovered by an ammonia–water power/cooling cogeneration system. Parametric investigations are conducted to evaluate the effects of decision variables on the performances of the GT-MHR and combined cycles. The performances of these cycles are then optimized from the viewpoints of first law, second law and exergoeconomics. It is found that, combining the GT-MHR with ammonia–water cycle not only enhances the first and second law efficiencies of the GT-MHR, but also it improves the cycle performance from the exergoeconomic perspective. The results show that, when the optimization is based on the exergoeconomics, the unit cost of products is reduced by 5.4% in combining the two mentioned cycles. This is achieved with a just about 1% increase in total investment cost rate since the helium mass flow in the combined cycle is lower than that in the GT-MHR alone. - Highlights: • Application of exergetic cost theory to the combined GT-MHR/ammonia–water cycle. • Enhanced exergoeconomic performance for the combined cycle compared to the GT-MHR. • Comparable investment costs for the combined cycle and the GT-MHR alone

  20. Electronic properties of physisorbed helium

    Kossler, Sarah

    2011-01-01

    This thesis deals with electronic excitations of helium physisorbed on metal substrates. It is studied to what extent the electronic properties change compared to the gas phase due to the increased helium density and the proximity of the metal. Furthermore, the influence of different substrate materials is investigated systematically. To this end, up to two helium layers were adsorbed onto Ru (001), Pt (111), Cu (111), and Ag (111) surfaces in a custom-made cryostat. These samples were studied spectroscopically using synchrotron radiation and a time-of-flight detector. The experimental results were then analyzed in comparison with extensive theoretical model calculations.

  1. Electronic properties of physisorbed helium

    Kossler, Sarah

    2011-09-22

    This thesis deals with electronic excitations of helium physisorbed on metal substrates. It is studied to what extent the electronic properties change compared to the gas phase due to the increased helium density and the proximity of the metal. Furthermore, the influence of different substrate materials is investigated systematically. To this end, up to two helium layers were adsorbed onto Ru (001), Pt (111), Cu (111), and Ag (111) surfaces in a custom-made cryostat. These samples were studied spectroscopically using synchrotron radiation and a time-of-flight detector. The experimental results were then analyzed in comparison with extensive theoretical model calculations.

  2. Description and operating performance of a parallel-rail electric-arc system with helium driver gas for the Langley 6-inch expansion tube

    Moore, J. A.

    1976-01-01

    A parallel-rail arc-discharge system to heat and pressurize the initial helium driver gas of the Langley 6-inch expansion tube is described. This system was designed for a 2.44-m-long driver vessel rated at 138 MPa, with a distance between rails of 20.3 cm. Electric energy was obtained from a capacitor storage system rated at 12,000 V with a maximum energy of 5 MJ. Tests were performed over a range of energy from 1.74 MJ to the maximum value. The operating experience and system performance are discussed, along with results from a limited number of expansion-tube tests with air and carbon dioxide as test gases.

  3. Performance test results of helium gas circulator of mock-up test facility with full-scale reaction tube for HTTR hydrogen production system. Contract research

    Shimizu, Akira; Kato, Michio; Hayashi, Koji [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment] [and others

    2003-03-01

    Hydrogen production system by steam reforming of methane will be connected to the High Temperature Engineering Test Reactor (HTTR) of the Japan Atomic Energy Research Institute (JAERI) against development of nuclear heat utilization system. To obtain design and safety database of the HTTR hydrogen production system, mock-up test facility with full-scale reaction was constructed in FY 2001 and hydrogen of 120m{sup 3}N{sub /}h was successfully produced in overall performance test. This report describes performance test results of a helium gas circulator in this facility. The circulator performance curves regarding to pressure-rise, input power and adiabatic thermal efficiency at standard revolution number were made based on the measured flow-rate, temperature and pressure data in overall performance test. The circulator performance prediction code was made based on these performance curves. The code can calculate revolution number, electric power and temperature-rise of the circulator using flow-rate, inlet temperature, inlet pressure and pressure-rise data. The verification of the code was carried out with the test data in FY 2002. Total pressure loss of the helium gas circulation loop was also evaluated. The circulator should be operated in conditions such as pressure from 2.7MPa to 4.0MPa and flow-rate from 250g/s to 400g/s and at maximum pressure-rise of 250 kPa in test operation. It was confirmed in above verification and evaluations that the circulator had performance to satisfy above conditions within operation limitation of the circulator such as maximum input-power of 150 kW and maximum revolution number of 12,000 rpm. (author)

  4. Behaviour of helium after implantation in molybdenum

    Viaud, C.; Maillard, S.; Carlot, G.; Valot, C.; Gilabert, E.; Sauvage, T.; Peaucelle, C.; Moncoffre, N.

    2009-01-01

    This study deals with the behaviour of helium in a molybdenum liner dedicated to the retention of fission products. More precisely this work contributes to evaluate the release of implanted helium when the gas has precipitated into nanometric bubbles close to the free surface. A simple model dedicated to calculate the helium release in such a condition is presented. The specificity of this model lays on the assumption that the gas is in equilibrium with a simple distribution of growing bubbles. This effort is encouraging since the calculated helium release fits an experimental dataset with a set of parameters in good agreement with the literature

  5. Variable electricity and steam from salt, helium and sodium cooled base-load reactors with gas turbines and heat storage - 15115

    Forsberg, C.; McDaniel, P.; Zohuri, B.

    2015-01-01

    Advances in utility natural-gas-fired air-Brayton combed cycle technology is creating the option of coupling salt-, helium-, and sodium-cooled nuclear reactors to Nuclear air-Brayton Combined Cycle (NACC) power systems. NACC may enable a zero-carbon electricity grid and improve nuclear power economics by enabling variable electricity output with base-load nuclear reactor operations. Variable electricity output enables selling more electricity at times of high prices that increases plant revenue. Peak power is achieved using stored heat or auxiliary fuel (natural gas, bio-fuels, hydrogen). A typical NACC cycle includes air compression, heating compressed air using nuclear heat and a heat exchanger, sending air through a turbine to produce electricity, reheating compressed air, sending air through a second turbine, and exhausting to a heat recovery steam generator (HRSG). In the HRSG, warm air produces steam that is used to produce added electricity. For peak power production, auxiliary heat (natural gas, stored heat) is added before the air enters the second turbine to raise air temperatures and power output. Like all combined cycle plants, water cooling requirements are dramatically reduced relative to other power cycles because much of the heat rejection is in the form of hot air. (authors)

  6. Experimental study on the ( mu /sup 4/He)/sub 2S//sup +/ metastable system in helium gas

    Bertin, A; Duclos, J; Gastaldi, Ugo; Gorini, G; Neri, G; Picard, J; Pitzurra, O; Placci, A; Polacco, E; Torelli, G; Vitale, A; Zavattini, E

    1975-01-01

    The authors report the results of an experimental investigation on the properties of the ( mu He)/sub 2S//sup +/ metastable muonic system, which was performed stopping negative muons in a pure helium target at pressures ranging from 10 to 50 atm, and observing the total yield and the differential time distribution of the X-rays released in delayed coincidence with the arrival of muons. At each pressure P, information was obtained on the following quantities: a) the total disappearance rate lambda /sub 2S, tot/(P) of the ( mu He)/sub 2S//sup +/ system, b) the disappearance rates lambda /sub A/(P) and lambda /sub St/(P) of the ( mu He)/sub 2S//sup +/ system for external Auger effect and Stark-mixing collisions. (35 refs).

  7. Helium cooling of fusion reactors

    Wong, C.P.C.; Baxi, C.; Bourque, R.; Dahms, C.; Inamati, S.; Ryder, R.; Sager, G.; Schleicher, R.

    1994-01-01

    On the basis of worldwide design experience and in coordination with the evolution of the International Thermonuclear Experimental Reactor (ITER) program, the application of helium as a coolant for fusion appears to be at the verge of a transition from conceptual design to engineering development. This paper presents a review of the use of helium as the coolant for fusion reactor blanket and divertor designs. The concept of a high-pressure helium cooling radial plate design was studied for both ITER and PULSAR. These designs can resolve many engineering issues, and can help with reaching the goals of low activation and high performance designs. The combination of helium cooling, advanced low-activation materials, and gas turbine technology may permit high thermal efficiency and reduced costs, resulting in the environmental advantages and competitive economics required to make fusion a 21st century power source. ((orig.))

  8. Laser spectroscopy of antiprotonic helium

    Hori, M

    2005-01-01

    When antiprotons (i.e. the antimatter counterpart of protons) are stopped in helium gas, 97% of them annihilate within picoseconds by reacting with the helium nuclei; a 3% fraction, however, survive with an anomalously long lifetime of several microseconds. This longevity is due to the formation of antiprotonic helium, which is a three-body Rydberg atom composed of an antiproton, electron, and helium nucleus. The ASACUSA experimental collaboration has recently synthesized large numbers of these atoms using CERN's Antiproton Decelerator facility, and measured the atom's transition frequencies to 60 parts per billion by laser spectroscopy. By comparing the experimental results with recent three-body QED calculations and the known antiproton cyclotron frequency, we were able to show that the antiproton mass and charge are the same as the corresponding proton values to a precision of 10 parts per billion. Ongoing and future series of experiments will further improve the experimental precision by using chirp-compe...

  9. Tuning the conductivity threshold and carrier density of two-dimensional electron gas at oxide interfaces through interface engineering

    H. J. Harsan Ma

    2015-08-01

    Full Text Available The two-dimensional electron gas (2DEG formed at the perovskite oxides heterostructures is of great interest because of its potential applications in oxides electronics and nanoscale multifunctional devices. A canonical example is the 2DEG at the interface between a polar oxide LaAlO3 (LAO and non-polar SrTiO3 (STO. Here, the LAO polar oxide can be regarded as the modulating or doping layer and is expected to define the electronic properties of 2DEG at the LAO/STO interface. However, to practically implement the 2DEG in electronics and device design, desired properties such as tunable 2D carrier density are necessary. Here, we report the tuning of conductivity threshold, carrier density and electronic properties of 2DEG in LAO/STO heterostructures by insertion of a La0.5Sr0.5TiO3 (LSTO layer of varying thicknesses, and thus modulating the amount of polarization of the oxide over layers. Our experimental result shows an enhancement of carrier density up to a value of about five times higher than that observed at the LAO/STO interface. A complete thickness dependent metal-insulator phase diagram is obtained by varying the thickness of LAO and LSTO providing an estimate for the critical thickness needed for the metallic phase. The observations are discussed in terms of electronic reconstruction induced by polar oxides.

  10. Future of the gas industry. Energy carriers instead of power source?

    Bothe, David; Janssen, Matthias; Riechmann, Christoph

    2017-01-01

    For a long time, natural gas was considered as an ideal bridge technology for the energy transition because of the relatively low CO_2 content. With increasing decarbonisation of electricity generation by renewable energies and the associated political vision of a far-reaching electrification of energy applications, in particular in the heat sector, the gas sector is, however, threatened to be overtaken by the renewables. This creates increasing uncertainty for business models and investments in the natural gas sector itself, but also potentially high macroeconomic costs of the energy transition. It can be shown that such a development is not unavoidable if the gas sector succeeds in using the existing possibilities cleverly. Thereby the continued use of existing gas infrastructure plays a central role. For use of the opportunities, however, a paradigm shift in politics, regulation and natural gas sector is necessary, whose key points are developed in this article. [de

  11. Thermodynamic properties of helium in the range from 20 to 15000C and 1 to 100 bar. Reactor core design of high-temperature gas-cooled reactors. Pt. 1

    Kipke, H.E.; Stoehr, A.; Banerjea, A.; Hammeke, K.; Huepping, N.

    1978-12-01

    The following report presents in tabular form the safety standard of the nuclear safety standard commission (KTA) on reactor core design of high-temperature gas-cooled reactors. Part 1: Calculation of thermodynamic properties of helium The basis of the present work is the data and formulae given by H. Petersen for the calculation of density, specific heat, thermal conductivity and dynamic viscosity of helium together with the formula for their standard deviations in the range of temperature and pressure stated above. The relations for specific enthalpy and specific entropy have been derived from density and specific heat, whereby specific heat is assumed constant over the given range of temperature and pressure. The latter section of this report contains tables of thermodynamic properties of helium calculated from the equations stated earlier in this paper. (orig.) [de

  12. Numerical modeling of carrier gas flow in atomic layer deposition vacuum reactor: A comparative study of lattice Boltzmann models

    Pan, Dongqing; Chien Jen, Tien; Li, Tao; Yuan, Chris

    2014-01-01

    This paper characterizes the carrier gas flow in the atomic layer deposition (ALD) vacuum reactor by introducing Lattice Boltzmann Method (LBM) to the ALD simulation through a comparative study of two LBM models. Numerical models of gas flow are constructed and implemented in two-dimensional geometry based on lattice Bhatnagar–Gross–Krook (LBGK)-D2Q9 model and two-relaxation-time (TRT) model. Both incompressible and compressible scenarios are simulated and the two models are compared in the aspects of flow features, stability, and efficiency. Our simulation outcome reveals that, for our specific ALD vacuum reactor, TRT model generates better steady laminar flow features all over the domain with better stability and reliability than LBGK-D2Q9 model especially when considering the compressible effects of the gas flow. The LBM-TRT is verified indirectly by comparing the numerical result with conventional continuum-based computational fluid dynamics solvers, and it shows very good agreement with these conventional methods. The velocity field of carrier gas flow through ALD vacuum reactor was characterized by LBM-TRT model finally. The flow in ALD is in a laminar steady state with velocity concentrated at the corners and around the wafer. The effects of flow fields on precursor distributions, surface absorptions, and surface reactions are discussed in detail. Steady and evenly distributed velocity field contribute to higher precursor concentration near the wafer and relatively lower particle velocities help to achieve better surface adsorption and deposition. The ALD reactor geometry needs to be considered carefully if a steady and laminar flow field around the wafer and better surface deposition are desired

  13. Numerical modeling of carrier gas flow in atomic layer deposition vacuum reactor: A comparative study of lattice Boltzmann models

    Pan, Dongqing; Chien Jen, Tien [Department of Mechanical Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201 (United States); Li, Tao [School of Mechanical Engineering, Dalian University of Technology, Dalian 116024 (China); Yuan, Chris, E-mail: cyuan@uwm.edu [Department of Mechanical Engineering, University of Wisconsin-Milwaukee, 3200 North Cramer Street, Milwaukee, Wisconsin 53211 (United States)

    2014-01-15

    This paper characterizes the carrier gas flow in the atomic layer deposition (ALD) vacuum reactor by introducing Lattice Boltzmann Method (LBM) to the ALD simulation through a comparative study of two LBM models. Numerical models of gas flow are constructed and implemented in two-dimensional geometry based on lattice Bhatnagar–Gross–Krook (LBGK)-D2Q9 model and two-relaxation-time (TRT) model. Both incompressible and compressible scenarios are simulated and the two models are compared in the aspects of flow features, stability, and efficiency. Our simulation outcome reveals that, for our specific ALD vacuum reactor, TRT model generates better steady laminar flow features all over the domain with better stability and reliability than LBGK-D2Q9 model especially when considering the compressible effects of the gas flow. The LBM-TRT is verified indirectly by comparing the numerical result with conventional continuum-based computational fluid dynamics solvers, and it shows very good agreement with these conventional methods. The velocity field of carrier gas flow through ALD vacuum reactor was characterized by LBM-TRT model finally. The flow in ALD is in a laminar steady state with velocity concentrated at the corners and around the wafer. The effects of flow fields on precursor distributions, surface absorptions, and surface reactions are discussed in detail. Steady and evenly distributed velocity field contribute to higher precursor concentration near the wafer and relatively lower particle velocities help to achieve better surface adsorption and deposition. The ALD reactor geometry needs to be considered carefully if a steady and laminar flow field around the wafer and better surface deposition are desired.

  14. Helium turbo-expander with an alternator

    Akiyama, Yoshitane

    1980-01-01

    Study was made on a helium turbo-expander, the heart of helium refrigerator systems, in order to develop a system which satisfies the required conditions. A helium turbo-expander with externally pressurized helium gas bearings at the temperature of liquid nitrogen and an alternator as a brake have been employed. The essential difference between a helium turbo-expander and a nitrogen turbo-expander was clarified. The gas bearing lubricated with nitrogen at room temperature and the gas bearing lubricated with helium at low temperature were tested. The flow rate of helium in a helium refrigerator for a large superconducting magnet is comparatively small, therefore a helium turbine must be small, but the standard for large turbine design can be applied to such small turbine. Using the alternator as a brake, the turbo-expander was easily controllable electrically. The prototype turbo-expander was made, and the liquefaction test with it and MHD power generation test were carried out. (Kako, I.)

  15. Effect of helium plasma gas flow rate on the properties of WC-12 wt.%Co coatings sprayed by atmospheric plasma

    Mihailo R. Mrdak

    2014-06-01

    Full Text Available The cermet coatings of WC-12wt.%Co are extensively used to improve the wear resistance of a wide range of technical components. This paper analyses the influence of the plasma gas flow of helium on the microstructure and mechanical properties of WC-12wt.%Co coatings deposited by plasma spraying at atmospheric pressure (APS. In order to obtain homogeneous and denser coatings, three different flows of He ( 8 l/min., 16 l/min. and 32 l/min were used in the research. With the application of He, coatings achieved higher values of hardness due to less degradation of the primary WC carbides. The main goal was to deposit dense and homogeneous layers of WC-12wt.%Co coatings with improved wear resistance for different applications. The test results of the microstructure of the layers were evaluated under a light microscope. The analysis of the microstructure and the mechanical properties of the deposited layers was made in accordance with the standard of Pratt-Whitney. The morphology of the powder particles and the microstructure of the best coating was examined on the SEM (scanning electron microscope. The evaluation of the mechanical properties of the layers was done by applying the HV0.3 method for microhardness testing and by applying tensile testing to test the bond strength. The research has shown that the flow of He plasma gas significantly affects the microstructure, the mechanical properties and the structure of WC-12 wt.%Co coatings.

  16. Preliminary studies of using preheated carrier gas for on-line membrane extraction of semivolatile organic compounds.

    Liu, Xinyu; Pawliszyn, Janusz

    2007-04-01

    In this paper, we present results for the on-line determination of semivolatile organic compounds (SVOCs) in air using membrane extraction with a sorbent interface-ion mobility spectrometry (MESI-IMS) system with a preheated carrier (stripping) gas. The mechanism of the mass transfer of SVOCs across a membrane was initially studied. In comparison with the extraction of volatile analytes, the mass transfer resistance that originated from the slow desorption from the internal membrane surface during the SVOC extraction processes should be taken into account. A preheated carrier gas system was therefore built to facilitate desorption of analytes from the internal membrane surface. With the benefit of a temperature gradient existing between the internal and external membrane surfaces, an increase in the desorption rate of a specific analyte at the internal surface and the diffusion coefficient within the membrane could be achieved while avoiding a decrease of the distribution constant on the external membrane interface. This technique improved both the extraction rate and response times of the MESI-IMS system for the analysis of SVOCs. Finally, the MESI-IMS system was shown to be capable of on-site measurement by monitoring selected polynuclear aromatic hydrocarbons emitted from cigarette smoke.

  17. Pressure transients analysis of a high-temperature gas-cooled reactor with direct helium turbine cycle

    Dang, M.; Dupont, J. F.; Jacquemoud, P.; Mylonas, R. [Eidgenoessisches Inst. fuer Reaktorforschung, Wuerenlingen (Switzerland)

    1981-01-15

    The direct coupling of a gas cooled reactor with a closed gas turbine cycle leads to a specific dynamic plant behaviour, which may be summarized as follows: a) any operational transient involving a variation of the core mass flow rate causes a variation of the pressure ratio of the turbomachines and leads unavoidably to pressure and temperature transients in the gas turbine cycle; and b) very severe pressure equalization transients initiated by unlikely events such as the deblading of one or more turbomachines must be taken into account. This behaviour is described and illustrated through results gained from computer analyses performed at the Swiss Federal Institute for Reactor Research (EIR) in Wurenlingen within the scope of the Swiss-German HHT project.

  18. Helium crystals

    Lipson, S.G.

    1987-01-01

    Hexagonal close-packed helium crystals in equilibrium with superfluid have been found to be one of the few systems in which an anisotropic solid comes into true thermodynamic equilibrium with its melt. The discovery of roughening transitions at the liquid-solid interface have shown this system to be ideal for the study of the statistical mechanics of interface structures. We describe the effect of roughening on the shape and growth of macroscopic crystals from both the theoretical and experimental points of view. (author)

  19. Implementation of gas concentration measurement systems using mass spectrometry in containment thermal-hydraulics test facilities: different approaches for calibration and measurement with steam/air/helium mixtures

    Auban, O.; Malet, J.; Brun, P.; Brinster, J.; Quillico, J. J.; Studer, E.

    2003-01-01

    . This work concerns measurement of steam-air-helium mixtures of any composition distributed in pressurized vessels. The developed systems provide concentration point measurements at typically a few tens of different locations in the facility vessels. This paper will give an overview of the three different measurement systems and will address the main difficulties encountered to develop these systems such as those related to the sample pressure reduction or to the presence of water vapor. The paper focuses on different attempts and approaches to generate the calibration gas mixtures containing water vapor and calibrate the QMS. Even if the calibration procedures still have to be improved, some recently acquired data are here to prove the promising achievements of the technique

  20. Adapting the deep burn in-core fuel management strategy for the gas turbine - modular helium reactor to a uranium-thorium fuel

    Talamo, Alberto [Department of Nuclear and Reactor Physics, Royal Institute of Technology, Roslagstullsbacken 21, S-10691, Stockholm (Sweden)]. E-mail: alby@neutron.kth.se; Gudowski, Waclaw [Department of Nuclear and Reactor Physics, Royal Institute of Technology, Roslagstullsbacken 21, S-10691, Stockholm (Sweden)

    2005-11-15

    In 1966, Philadelphia Electric has put into operation the Peach Bottom I nuclear reactor, it was the first high temperature gas reactor (HTGR); the pioneering of the helium-cooled and graphite-moderated power reactors continued with the Fort St. Vrain and THTR reactors, which operated until 1989. The experience on HTGRs lead General Atomics to design the gas turbine - modular helium reactor (GT-MHR), which adapts the previous HTGRs to the generation IV of nuclear reactors. One of the major benefits of the GT-MHR is the ability to work on the most different types of fuels: light water reactors waste, military plutonium, MOX and thorium. In this work, we focused on the last type of fuel and we propose a mixture of 40% thorium and 60% uranium. In a uranium-thorium fuel, three fissile isotopes mainly sustain the criticality of the reactor: {sup 235}U, which represents the 20% of the fresh uranium, {sup 233}U, which is produced by the transmutation of fertile {sup 232}Th, and {sup 239}Pu, which is produced by the transmutation of fertile {sup 238}U. In order to compensate the depletion of {sup 235}U with the breeding of {sup 233}U and {sup 239}Pu, the quantity of fertile nuclides must be much larger than that one of {sup 235}U because of the small capture cross-section of the fertile nuclides, in the thermal neutron energy range, compared to that one of {sup 235}U. At the same time, the amount of {sup 235}U must be large enough to set the criticality condition of the reactor. The simultaneous satisfaction of the two above constrains induces the necessity to load the reactor with a huge mass of fuel; that is accomplished by equipping the fuel pins with the JAERI TRISO particles. We start the operation of the reactor with loading fresh fuel into all the three rings of the GT-MHR and after 810 days we initiate a refueling and shuffling schedule that, in 9 irradiation periods, approaches the equilibrium of the fuel composition. The analysis of the k {sub eff} and mass

  1. Adapting the deep burn in-core fuel management strategy for the gas turbine - modular helium reactor to a uranium-thorium fuel

    Talamo, Alberto; Gudowski, Waclaw

    2005-01-01

    In 1966, Philadelphia Electric has put into operation the Peach Bottom I nuclear reactor, it was the first high temperature gas reactor (HTGR); the pioneering of the helium-cooled and graphite-moderated power reactors continued with the Fort St. Vrain and THTR reactors, which operated until 1989. The experience on HTGRs lead General Atomics to design the gas turbine - modular helium reactor (GT-MHR), which adapts the previous HTGRs to the generation IV of nuclear reactors. One of the major benefits of the GT-MHR is the ability to work on the most different types of fuels: light water reactors waste, military plutonium, MOX and thorium. In this work, we focused on the last type of fuel and we propose a mixture of 40% thorium and 60% uranium. In a uranium-thorium fuel, three fissile isotopes mainly sustain the criticality of the reactor: 235 U, which represents the 20% of the fresh uranium, 233 U, which is produced by the transmutation of fertile 232 Th, and 239 Pu, which is produced by the transmutation of fertile 238 U. In order to compensate the depletion of 235 U with the breeding of 233 U and 239 Pu, the quantity of fertile nuclides must be much larger than that one of 235 U because of the small capture cross-section of the fertile nuclides, in the thermal neutron energy range, compared to that one of 235 U. At the same time, the amount of 235 U must be large enough to set the criticality condition of the reactor. The simultaneous satisfaction of the two above constrains induces the necessity to load the reactor with a huge mass of fuel; that is accomplished by equipping the fuel pins with the JAERI TRISO particles. We start the operation of the reactor with loading fresh fuel into all the three rings of the GT-MHR and after 810 days we initiate a refueling and shuffling schedule that, in 9 irradiation periods, approaches the equilibrium of the fuel composition. The analysis of the k eff and mass evolution, reaction rates, neutron flux and spectrum at the

  2. Helium Extraction from LNG End Flash

    Kim, Donghoi

    2014-01-01

    Helium is an invaluable element as it is widely used in industry such as cryo-genics and welding due to its unique properties. However, helium shortage is expected in near future because of increasing demand and the anxiety of sup-ply. Consequently, helium production has attracted the attention of industry. The main source of He is natural gas and extracting it from LNG end-flash is considered as the most promising way of producing crude helium. Thus, many process suppliers have proposed proc...

  3. Isothermal gas chromatography of short-lived Hf isotopes and element 104 in chlorinating, oxygen containing carrier gas

    Jost, D.T.; Dressler, R.; Eichler, B.; Piguet, D.; Tuerler, A.; Gaeggeler, H.W.; Gaertner, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Grantz, M.; Huebener, S. [FZR (Germany); Buklanov, G.; Lebedev, V.; Timkhin, S.; Vedeneev, M.V.; Yakushev, A.; Zvara, I. [Joint Inst. for Nuclear Research, Dubna (Russian Federation)

    1997-09-01

    Based on thermodynamic state functions retention times of Hf and element 104 were calculated in the case of the simple adsorption of the tetrachlorides and the case of a complex adsorption involving a substitution process with oxygen in the chlorinating gas. Preliminary results for {sup 261}104 and Hf are shown. (author) 1 fig., 1 tab., 3 refs.

  4. Review of Membranes for Helium Separation and Purification

    Colin A. Scholes

    2017-02-01

    Full Text Available Membrane gas separation has potential for the recovery and purification of helium, because the majority of membranes have selectivity for helium. This review reports on the current state of the research and patent literature for membranes undertaking helium separation. This includes direct recovery from natural gas, as an ancillary stage in natural gas processing, as well as niche applications where helium recycling has potential. A review of the available polymeric and inorganic membranes for helium separation is provided. Commercial gas separation membranes in comparable gas industries are discussed in terms of their potential in helium separation. Also presented are the various membrane process designs patented for the recovery and purification of helium from various sources, as these demonstrate that it is viable to separate helium through currently available polymeric membranes. This review places a particular focus on those processes where membranes are combined in series with another separation technology, commonly pressure swing adsorption. These combined processes have the most potential for membranes to produce a high purity helium product. The review demonstrates that membrane gas separation is technically feasible for helium recovery and purification, though membranes are currently only applied in niche applications focused on reusing helium rather than separation from natural sources.

  5. Helium supply demand in future years

    Laverick, C.

    1975-01-01

    Adequate helium will be available to the year 2000 AD to meet anticipated helium demands for present day applications and the development of new superconducting technologies of potential importance to the nation. It is almost certain that there will not be enough helium at acceptable financial and energy cost after the turn of the century to meet the needs of the many promising helium based technologies now under development. Serious consideration should be given to establishing priorities in development and application based upon their relative value to the country. In the first half of the next century, three ways of estimating helium demand lead to cumulative ranges of from 75 to 125 Gcf (economic study), 89 to 470 Gcf (projected national energy growth rates) and 154 to 328 Gcf (needs for new technologies). These needs contrast with estimated helium resources in natural gas after 2000 AD which may be as low as 10 or 126 Gcf depending upon how the federal helium program is managed and the nation's natural gas resources are utilized. The technological and financial return on a modest national investment in further helium storage and a rational long term helium program promises to be considerable

  6. Evaluation of a novel helium ionization detector within the context of (low-)flow modulation comprehensive two-dimensional gas chromatography.

    Franchina, Flavio A; Maimone, Mariarosa; Sciarrone, Danilo; Purcaro, Giorgia; Tranchida, Peter Q; Mondello, Luigi

    2015-07-10

    The present research is focused on the use and evaluation of a novel helium ionization detector, defined as barrier discharge ionization detector (BID), within the context of (low-)flow modulation comprehensive two-dimensional gas chromatography (FM GC×GC). The performance of the BID device was compared to that of a flame ionization detector (FID), under similar FM GC×GC conditions. Following development and optimization of the FM GC×GC method, the BID was subjected to fine tuning in relation to acquisition frequency and discharge flow. Moreover, the BID performance was measured and compared to that of the FID, in terms of extra-column band broadening, sensitivity and dynamic range. The comparative study was carried out by using standard compounds belonging to different chemical classes, along with a sample of diesel fuel. Advantages and disadvantages of the BID system, also within the context of FM GC×GC, are critically discussed. In general, the BID system was characterized by a more limited dynamic range and increased sensitivity, compared to the FID. Additionally, BID and FID contribution to band broadening was found to be similar under the operational conditions applied. Particular attention was devoted to the behaviour of the FM GC×GC-BID system toward saturated and aromatic hydrocarbons, for a possible future use in the field of mineral-oil food contamination research. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Radiation Protection Practices during the Helium Circulator Maintenance of the 10 MW High Temperature Gas-Cooled Reactor-Test Module (HTR-10

    Chengxiang Guo

    2016-01-01

    Full Text Available Current radiation protection methodology offers abundant experiences on light-water reactors, but very few studies on high temperature gas-cooled reactor (HTR. To fill this gap, a comprehensive investigation was performed to the radiation protection practices in the helium circulator maintenance of the Chinese 10 MW HTR test module (HTR-10 in this paper. The investigation reveals the unique behaviour of HTR-10’s radiation sources in the maintenance as well as its radionuclide species and presents the radiation protection methods that were tailored to these features. Owing to these practices, the radioactivity level was kept low throughout the maintenance and only low-level radioactive waste was generated. The quantitative analysis further demonstrates that the decontamination efficiency was over 89% for surface contamination and over 34% for γ dose rate and the occupational exposure was much lower than both the limits of regulatory and the exposure levels in comparable literature. These results demonstrate the effectiveness of the reported radiation protection practices, which directly provides hands-on experience for the future HTR-PM reactor and adds to the completeness of the radiation protection methodology.

  8. A new boil-off gas re-liquefaction system for LNG carriers based on dual mixed refrigerant cycle

    Tan, Hongbo; Shan, Siyu; Nie, Yang; Zhao, Qingxuan

    2018-06-01

    A new boil-off gas (BOG) re-liquefaction system for LNG carriers has been proposed to improve the system energy efficiency. Two cascade mixed refrigerant cycles (or dual mixed refrigerant cycle, DMR) are used to provide the cooling capacity for the re-liquefaction of BOG. The performance of the new system is analysed on the basis of the thermodynamic data obtained in the process simulation in Aspen HYSYS software. The results show that the power consumed in the BOG compressor and the high-temperature mixed refrigerant compressor could be saved greatly due to the reduced mass flow rates of the processed fluids. Assuming the re-liquefaction capacity of the investigated system is 4557.6 kg/h, it is found that the total power consumption can be reduced by 25%, from 3444 kW in the existing system to 2585.8 kW in the proposed system. The coefficient of performance (COP) of 0.25, exergy efficiency of 41.3% and the specific energy consumption (SEC) of 0.589 kWh/kg(LNG) could be achieved in the new system. It exhibits 33% of improvement in the COP and exergy efficiency in comparison with the corresponding values of the existing system. It indicates that employing the DMR based BOG re-liquefaction system could improve the system energy efficiency of LNG carriers substantially.

  9. Near field characteristics of buoyant helium plumes

    pressure tubing. Helium gas enters the bottom of the settling chamber, passing through two ... A 40 mesh, flat stainless steel screen is placed across the orifice exit. ... PIV and PLIF measurements are carried out in phase resolved manner.

  10. Commercial helium reserves, continental rifting and volcanism

    Ballentine, C. J.; Barry, P. H.; Hillegonds, D.; Fontijn, K.; Bluett, J.; Abraham-James, T.; Danabalan, D.; Gluyas, J.; Brennwald, M. S.; Pluess, B.; Seneshens, D.; Sherwood Lollar, B.

    2017-12-01

    Helium has many industrial applications, but notably provides the unique cooling medium for superconducting magnets in medical MRI scanners and high energy beam lines. In 2013 the global supply chainfailed to meet demand causing significant concern - the `Liquid Helium Crisis' [1]. The 2017 closure of Quatar borders, a major helium supplier, is likely to further disrupt helium supply, and accentuates the urgent need to diversify supply. Helium is found in very few natural gas reservoirs that have focused 4He produced by the dispersed decay (a-particle) of U and Th in the crust. We show here, using the example of the Rukwa section of the Tanzanian East African Rift, how continental rifting and local volcanism provides the combination of processes required to generate helium reserves. The ancient continental crust provides the source of 4He. Rifting and associated magmatism provides the tectonic and thermal mechanism to mobilise deep fluid circulation, focusing flow to the near surface along major basement faults. Helium-rich springs in the Tanzanian Great Rift Valley were first identified in the 1950's[2]. The isotopic compositions and major element chemistry of the gases from springs and seeps are consistent with their release from the crystalline basement during rifting [3]. Within the Rukwa Rift Valley, helium seeps occur in the vicinity of trapping structures that have the potential to store significant reserves of helium [3]. Soil gas surveys over 6 prospective trapping structures (1m depth, n=1486) show helium anomalies in 5 out of the 6 at levels similar to those observed over a known helium-rich gas reservoir at 1200m depth (7% He - Harley Dome, Utah). Detailed macroseep gas compositions collected over two days (n=17) at one site allows us to distinguish shallow gas contributions and shows the deep gas to contain between 8-10% helium, significantly increasing resource estimates based on uncorrected values (1.8-4.2%)[2,3]. The remainder of the deep gas is

  11. Effects of product form and boron addition on the creep damage in the modified Hastelloy X alloys in a simulated HTGR helium gas environment

    Nakasone, Yuji; Tanabe, Tatsuhiko; Tsuji, Hirokazu; Nakajima, Hajime.

    1992-01-01

    The present paper investigates early-stage-creep damage of Hastelloy XR and XR-II alloys, modified versions of Hastelloy X alloy, which have been developed in Japan as most promising candidate structural alloys for Japanese high-temperature gas-cooled reactors (HTGRs). Creep tests were made on Hastelloy XR forging, tube and XR-II tube at 1,123 to 1,273 K in a simulated HTGR helium gas environment. The tests were interrupted at different strain levels of up to 5 % in order to evaluate creep damage via intergranular voids. The void sizes along grain boundaries and the A-parameter, the ratio of the number of damaged grain boundaries, on which one or more voids are found, to that of the total grain boundaries observed are used in order to evaluate creep damage. Statistical analysis of the A-parameter as well as the void sizes reveals that the values of the parameter show wide variations and follow the Weibull distribution, reflecting spatial randomness of the voids. The void sizes along grain boundaries, on the other hand, follow the log-normal distribution. The maximum void size d max and the mean value of the A-parameter A m are calculated and plotted against interruption creep strain ε int . The resultant d max vs. ε int and A m vs. ε int diagrams show that Hastelloy XR forging had suffered more damage than Hastelloy XR tube; nevertheless, the forging has longer interruption life, or the time to reach a given interruption creep strain. The result indicates that grains may have been deformed more easily in Hastelloy XR in the form of tube than in the form of forging. The diagrams also imply that the addition of boron has suppressed the nucleation as well as the growth of voids and thus has brought about longer interruption life of Hastelloy XR-II. (author)

  12. Low-temperature centrifugal helium compressor

    Kawada, M.; Togo, S.; Akiyama, Y.; Wada, R.

    1974-01-01

    A centrifugal helium compressor with gas bearings, which can be operated at the temperature of liquid nitrogen, has been investigated. This compressor has the advantages that the compression ratio should be higher than the room temperature operation and that the contamination of helium could be eliminated. The outer diameter of the rotor is 112 mm. The experimental result for helium gas at low temperature shows a flow rate of 47 g/s and a compression ratio of 1.2 when the inlet pressure was 1 ata and the rotational speed 550 rev/s. The investigation is now focused on obtaining a compression ratio of 1.5. (author)

  13. Studies on the separation of hydrogen isotopes and spin isomers by gas chromatography

    Pushpa, K.K.; Annaji Rao, K.

    2000-08-01

    Separation and analysis of mixture of hydrogen isotopes has gained considerable importance because of various applications needing different isotopes in lasers, nuclear reactions and tracer or labelled compounds. In the literature gas chromatographic methods are reported using columns packed with partly dehydrated or thoroughly dehydrated alumina/molecular sieve stationary phase at 77 deg K with helium, neon and even hydrogen or deuterium as carrier gas. In the present study an attempt is made to compare the chromatographic behaviour of these two stationary phases using virgin and Fe doped form in partly dehydrated and thoroughly dehydrated state, using helium, neon, hydrogen and deuterium as carrier gas. The results of this study show that helium or neon carrier gas behave similarly broad peaks with some tailing. Sharp symmetric peaks are obtained with hydrogen or deuterium carrier gas. This is attributed to large hold up capacity for H 2 or D 2 at 77 deg K in these materials as compared to helium or neon. Spin isomers of H 2 or D 2 are separated on Fe free stationary phases, though ortho H 2 and HD are not resolved. Using a combination of Fe doped short column and plain alumina column, both maintained in dehydrated form, the effect of Fe doping on thermal equilibrium of ortho/para forms at 77 deg K is clearly demonstrated. (author)

  14. Study on cryogenic adsorption capability of trace nitrogen and methane by activated carbon for cooIant helium purification

    Chang Hua; Wu Zongxin

    2014-01-01

    A fixed-bed apparatus with dynamic two-route proportional gas mixing system was designed to investigate the cryogenic adsorption behavior of nitrogen and methane on activated carbon for designing the helium purification system of high-temperature gas-cooled reactors (HTGR). With helium as carrier gas and at the impurity partial pressure of tens Pa, experiments were performed at near atmospheric pressure and by dynamic column breakthrough method at -196°C. The breakthrough curves and desorption curves were measured. By analyzing the breakthrough curve, both the equilibrium adsorption capacity and the kinetic adsorption capacity at breakthrough point were determined. Based on mass-transfer zone model, the experimental breakthrough curves were analyzed. (author)

  15. Field investigation with regard to the impermeability of clay formations. Helium-4 soil gas surveys in sedimentary basins as a tentative study of secondary permeability in clayey sequences

    Lombardi, S.; Benvegnu, F.; Brondi, A.; Polizzano, C.

    1993-01-01

    This report deals with a tentative study for the detection of the secondary permeability in clayey formations conducted in several sedimentary basins in Central Italy, by means of geochemical methods. The main purposes are: to try a geochemical method, based on the distribution of deep origin gases in soil gas ( 4 He and 222 Rn), to detect buried fault systems and to study the permeability of clay as a potential migration pathway for nuclides of radioactive waste deposits; to verify the effectiveness of this method for the selection of suitable sites for radwaste disposal. This research programme consists in a collaboration between ENEA and the University of Rome within the communitarian programme for the disposal of high level and long-live radwaste. Investigations concerned sedimentary basins filled by sand-clay formations 1000-2000 meters thick and characterized by different tectonic: Era and Chiani-Paglia Valleys (Tuscany and North Latium), structural trenches due to extensive tectonics along the tyrrhenian edge, and Vasto region, a basin in the 'Adriatic foretrench', characterized by compressive tectonics. The investigated areas are near or directly correspond to geothermal fields or to hydrocarbon reservoirs supplying gases which may migrate upward along fractures. Almost 4000 soil gas samples were collected in the three surveyed areas; the sampling density was of about 1.5 points / km 2 , normally used in the regional scale surveys. The obtained results show that the observed helium anomalies are distributed or elongated according to the main tectonic features of the substratum (fault systems, fractures, deep structures); the magnitude of anomalies seems to correlate with the nature of the deep gas reservoir (i.e. oil in Vasto), geothermal reservoir in the Paglia valley. These observations seem to confirm that the presence of deep origin gases in soils is controlled by tectonics. Clay thickness does not significantly control the uprising of deep gases: in

  16. Determination of helium in beryl minerals

    Souza Barcellos, E. de.

    1985-08-01

    In order to obtain the diffusion coefficients of helium in beryl and phenacite samples at various temperatures, helium leak rates were measured in these minerals at these temperatures. Mass spectrometry (MS) was used to obtain helium leak rates and the gas flow was plotted against time. The gas quantity determined by MS was first obtained at various temperatures until no helium leak rate was detected. After that, these samples were irradiated with fast neutrons to produce helium which was measured again. This procedure was used to estimate the experimental error. The quantity of helium produced by interaction of gamma radiation with beryl minerals was theoretically calculated from the amount of thorium-232 at the neighbourhood of the samples. The quantity of helium produced in the minerals due to uranium and thorium decay was calculated using the amount of these heavy elements, and the results were compared with the amounts determined by MS. The amount of potassium-40 was determined in order to derive the quantity of argonium-40, since some workers found argonium in excess in these minerals. The quantity of helium in the beryl samples (s) was determined in the center and in the surface of the samples in order to obtain informations about the effectiveness of the Be(α, η) He reaction. Beryl and phenacite minerals were choosen in this research since they are opposite each other with respect to the helium contents. Both have beryllium in their compositon but beryl hold a large amount of helium while phenacite, in spite of having about three times more beryllium than beryl, do not hold the gas. (author) [pt

  17. Nitrogen versus helium: effects of the choice of the atomizing gas on the structures of Fe50Ni30Si10B10 and Fe32Ni36Ta7Si8B17 powders

    Zambon, A.

    2004-01-01

    Gas atomization can produce, besides a possible significant degree of undercooling, high cooling rates, whose extent depends on the size of the droplets, on their velocity with respect to the surrounding medium, on the thermo-physical properties of both the alloy and the gas, and of course on the operating conditions such as melt overheating and gas-to-metal flow ratio. In this respect it is well-known that the atomizing gas can play a significant role in determining both the powder size distribution and the kind and mix of phases which result from the solidification and cooling processes. The microstructures and solidification morphologies of powders obtained from nitrogen and helium sonic gas atomization of two iron-nickel base glass forming alloys, Fe 50 Ni 30 Si 10 B 10 and Fe 32 Ni 36 Ta 7 Si 8 B 17 , were investigated by means of light microscopy, X-ray diffraction (XRD) and differential thermal analysis (DTA). The Fe 32 Ni 36 Ta 7 Si 8 B 17 alloy exhibits a higher proneness to the development of amorphous phase than the Fe 50 Ni 30 Si 10 B 10 alloy, while the effect of the higher speed attainable by the stream of helium with respect to that of nitrogen, affords not only to obtain a larger amount of particles in the finer size ranges, but also to affect the relative amounts of phases within the different size fractions

  18. Enhancement of energy performance in a boil-off gas re-liquefaction system of LNG carriers using ejectors

    Tan, Hongbo; Zhao, Qingxuan; Sun, Nannan; Li, Yanzhong

    2016-01-01

    Highlights: • An ejector-enhanced LNG boil-off gas (BOG) re-liquefaction system is proposed. • The new system has an improvement of 28% in COP over the existing system. • The specific energy consumption of the new system is reduced to 0.59 kW h/kg(BOG). • The power consumption of 754.1 kW is saved in the case study. - Abstract: An ejector-enhanced Liquefied Natural Gas (LNG) boil-off gas (BOG) re-liquefaction system is proposed to improve the energy efficiency of the existing system. In the new system, two ejectors are respectively used to reduce the energy loss in the expansion of the pressurized BOG and inject a part of fuel BOG into the compression system, and a recuperator is employed to recover the cold energy of the BOG exited from LNG tank. The performance improvement of the proposed system is analysed on the basis of the simulation in Aspen HYSYS. In the case of the re-liquefaction capacity of 4557.6 kg/h, the coefficient of performance (COP) and exergy efficiency can be increased by 28%, and the specific energy consumption (SEC) reduced from 0.756 to 0.59 kW h/kg(BOG) compared to the conventional BOG re-liquefaction system. Correspondingly, the power consumption of 754.1 kW is saved. This means that applying ejectors can effectively improve the energy efficiency of the existing BOG re-liquefaction system for LNG carriers.

  19. Studies on the feasibility of the LWRs waste-thorium in-core fuel cycle in the Gas Turbine-Modular Helium Reactor

    Talamo, Alberto

    2006-01-01

    The capability to operate on LWRs waste constitutes one of the major benefits of the Gas Turbine-Modular Helium Reactor; in this paper, it has been evaluated the possibility to incinerate the LWRs waste and to simultaneously breed fissile 233 U by fertile thorium. Since a mixture of pure 239 Pu-thorium has shown a quite poor neutron economy, the LWRs waste-thorium fuel performance has been also tested when plutonium and thorium are allocated in different TRISO particles. More precisely, when fissile and fertile actinides share the same TRISO kernel, the resonance at 0.29eV of the fission and capture microscopic cross sections of 239 Pu diminishes also the absorption rate of fertile 232 Th and thus it degrades the breeding process. Consequently, in the present studies, two different types of fuel have been utilized: the Driver Fuel, made of LWRs waste, and the Transmutation Fuel, made of fertile thorium. Since, in the thermal neutron energy range, the microscopic capture cross section of 232 Th is about 80-100 times smaller than the fission one of 239 Pu, setting thorium in particles with a large kernel and LWRs waste in particles with a small one makes the volume integrated reaction rates better equilibrated. At the light of the above consideration, which drives to load as much thorium as possible, for the Transmutation Fuel they have been selected the JAERI TRISO particles packed 40%; whereas, for the Driver Fuel they have been tested different packing fractions and kernel radii. Since no configuration allowed the reactor to work, the above procedure has been repeated when fertile particles are packed 20%; the latter choice permits over one year of operation, but the build up of 233 U represents only a small fraction of the depleted 239 Pu. Finally, the previous configuration has been also investigated when the fertile and fissile fuels share the same kernel or when the fertile fuel axially alternates with the fissile one. (author)

  20. The study of capability natural uranium as fuel cycle input for long life gas cooled fast reactors with helium as coolant

    Ariani, Menik, E-mail: menikariani@gmail.com; Satya, Octavianus Cakra; Monado, Fiber [Department of Physics, Faculty of Mathematics and Natural Sciences, Sriwijaya University, jl Palembang-Prabumulih km 32 Indralaya OganIlir, South of Sumatera (Indonesia); Su’ud, Zaki [Nuclear and Biophysics Research Division, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, jlGanesha 10, Bandung (Indonesia); Sekimoto, Hiroshi [CRINES, Tokyo Institute of Technology, 2-12-11N1-17 Ookayama, Meguro-Ku, Tokyo (Japan)

    2016-03-11

    The objective of the present research is to assess the feasibility design of small long-life Gas Cooled Fast Reactor with helium as coolant. GCFR included in the Generation-IV reactor systems are being developed to provide sustainable energy resources that meet future energy demand in a reliable, safe, and proliferation-resistant manner. This reactor can be operated without enrichment and reprocessing forever, once it starts. To obtain the capability of consuming natural uranium as fuel cycle input modified CANDLE burn-up scheme was adopted in this system with different core design. This study has compared the core with three designs of core reactors with the same thermal power 600 MWth. The fuel composition each design was arranged by divided core into several parts of equal volume axially i.e. 6, 8 and 10 parts related to material burn-up history. The fresh natural uranium is initially put in region 1, after one cycle of 10 years of burn-up it is shifted to region 2 and the region 1 is filled by fresh natural uranium fuel. This concept is basically applied to all regions, i.e. shifted the core of the region (i) into region (i+1) region after the end of 10 years burn-up cycle. The calculation results shows that for the burn-up strategy on “Region-8” and “Region-10” core designs, after the reactors start-up the operation furthermore they only needs natural uranium supply to the next life operation until one period of refueling (10 years).

  1. CALCULATED REGENERATOR PERFORMANCE AT 4 K WITH HELIUM-4 AND HELIUM-3

    Radebaugh, Ray; Huang Yonghua; O'Gallagher, Agnes; Gary, John

    2008-01-01

    The helium-4 working fluid in regenerative cryocoolers operating with the cold end near 4 K deviates considerably from an ideal gas. As a result, losses in the regenerator, given by the time-averaged enthalpy flux, are increased and are strong functions of the operating pressure and temperature. Helium-3, with its lower boiling point, behaves somewhat closer to an ideal gas in this low temperature range and can reduce the losses in 4 K regenerators. An analytical model is used to find the fluid properties that strongly influence the regenerator losses as well as the gross refrigeration power. The thermodynamic and transport properties of helium-3 were incorporated into the latest NIST regenerator numerical model, known as REGEN3.3, which was used to model regenerator performance with either helium-4 or helium-3. With this model we show how the use of helium-3 in place of helium-4 can improve the performance of 4 K regenerative cryocoolers. The effects of operating pressure, warm-end temperature, and frequency on regenerators with helium-4 and helium-3 are investigated and compared. The results are used to find optimum operating conditions. The frequency range investigated varies from 1 Hz to 30 Hz, with particular emphasis on higher frequencies

  2. 80 K - Helium circuit with innovative, gas-bearing, oil-free turbo compressor. Conception, realization, commissioning and test of the 80 K refrigeration supply for the superconducting electron source at HZB; 80 K - Helium-Kreis mit innovativem, gasgelagertem, oelfreiem Turbokompressor. Konzeption, Realisierung, Inbetriebnahme und Test der 80 K-Kaelteversorgung fuer die supraleitenden Elektronenquelle am HZB

    Gloeckner, Felix [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany)

    2017-07-01

    The system presented in this paper supplies the test module for the superconducting electron source (GunLab) at the Helmholtz-Zentrum Berlin (HZB) with 500 W cooling capacity at 80 K.Since direct evaporation of liquid nitrogen in the module is not desirable for safety reasons, the system operates with an intermediate helium circuit. In order to use not only the latent cold of liquid nitrogen, but also the sensitive component, a new concept consisting of a dual heat exchanger and a bath cryostat is used. The coldbox also contains an adjustable bypass with integrated electric heater for test purposes.A new type of warm compressor is used to circulate the helium. The turbo compressor is oil-free, gas-stored and in helium-tight semi-hermetic design. In order to take advantage of these unique properties, Fischer Engineering AG has adapted the turbo compressor for use with helium.The paper concludes with a test of the system and an insight into the current operating experience, as well as a preview of the next, larger version of bERLinPro. [German] Die in diesem Paper vorgestellte Anlage versorgt das Testmodul fuer die supraleitende Elektronenquelle (GunLab) am Helmholtz-Zentrum Berlin (HZB) mit 500 W Kuehlleistung bei 80 K. Da eine Direktverdampfung von Fluessigstickstoff im Modul aus Sicherheitsgruenden nicht erwuenscht ist, arbeitet die Anlage mit einem Heliumzwischenkreis. Um nicht nur die latente Kaelte des fluessigen Stickstoffs, sondern auch den sensiblen Anteil zu nutzen, wird ein neues Konzept, bestehend aus einem Dualwaermeuebertrager und einem Badkryostaten verwendet. Die Coldbox enthaelt fuer Testzwecke darueber hinaus einen regelbaren Bypass mit inte-griertem elektrischem Heizer. Fuer die Umwaelzung des Heliums kommt eine neue Art eines warmen Kompressors zum Einsatz. Der Turbokom-pressor ist oelfrei, gasgelagert und in heliumdichter halb-hermetischer Bauweise ausgefuehrt. Um dessen, in dieser Leistungsklasse einzigartigen Eigenschaften zu nutzen, wurde der

  3. Design of a boil-off natural gas reliquefaction control system for LNG carriers

    Shin, Younggy; Lee, Yoon Pyo

    2009-01-01

    Onboard boil-off gas (BOG) reliquefaction is a new technology that liquefies BOG and returns it to the cargo tanks instead of burning it off during a voyage. For the commercial development of this technology, an object-oriented dynamic simulation is presented which facilitates the design of the plant and control system for the thermal process. A reliquefaction process based on the reverse Brayton cycle has been designed, and its static thermodynamic states at the design BOG load are presented. To make the cycle work for any BOG load, an idea was sought that would achieve a heat balance with the work extracted by the expander. Dynamic simulations were conducted for all operating modes, including start-up and idle. It was found that the expander exit temperature is the key process variable for control and that the process control works successfully when three actuators are activated in three different BOG load regimes. The study also shows that control of the separator pressure to keep the vapor fraction at the throttle valve exit as low as possible is an efficient method for purging nitrogen from BOG

  4. The installation of helium auxiliary systems in HTGR

    Qin Zhenya; Fu Xiaodong

    1993-01-01

    The inert gas Helium was chosen as reactor coolant in high temperature gas coolant reactor, therefore a set of Special and uncomplex helium auxiliary systems will be installed, the safe operation of HTR-10 can be safeguarded. It does not effect the inherent safety of HTR-10 MW if any one of all those systems were damaged during operation condition. This article introduces the design function and the system principle of all helium auxiliary systems to be installed in HTR-10. Those systems include: helium purification and its regeneration system, helium supply and storage system, pressure control and release system of primary system, dump system for helium auxiliary system and fuel handling, gaseous waste storage system, water extraction system for helium auxiliary systems and evacuation system for primary system

  5. Development of monitoring system using acoustic emission for detection of helium gas leakage for primary cooling system and flow-induced vibration for heat transfer tube of heat exchangers for the High Temperature Engineering Test Reactor (HTTR)

    Tachibana, Yukio; Kunitomi, Kazuhiko; Furusawa, Takayuki; Shinozaki, Masayuki; Satoh, Yoshiyuki; Yanagibashi, Minoru

    1998-10-01

    The High Temperature Engineering Test Reactor (HTTR) uses helium gas for its primary coolant, whose leakage inside reactor containment vessel is considered in design of the HTTR. It is necessary to detect leakage of helium gas at an early stage so that total amount of the leakage should be as small as possible. On the other hand, heat transfer tubes of heat exchangers of the HTTR are designed not to vibrate at normal operation, but the flow-induced vibration is to be monitored to provide against an emergency. Thus monitoring system of acoustic emission for detection of primary coolant leakage and vibration of heat transfer tubes was developed and applied to the HTTR. Before the application to the HTTR, leakage detection test was performed using 1/4 scaled model of outer tube of primary concentric hot gas duct. Result of the test covers detectable minimum leakage rate and effect of difference in gas, pressure, shape of leakage path and distance from the leaking point. Detectable minimum leakage rate was about 5 Ncc/sec. The monitoring system is promising in leakage detection, though countermeasure to noise is to be needed after the HTTR starts operating. (author)

  6. Separation of krypton from dissolver off-gas of a reprocessing plant using preparative gas chromatography

    Matoni, M.

    1984-02-01

    Kr-85 can be separated from the pre-purified purge air in the final processing step of the purification phase for dissolver off-gases of a reprocessing plant with the aid of preparative gas chromatography. Activated carbon adsorbers in combination with helium as carrier gas permits maximum gas mixture through-flow. A separation temperature of 30 0 C is considered optimal. An adsorbent volume of 40 dm 3 is necessary for processing the residual gas flow of 2.5 Nm 3 /h; the adsorbent is divided between 2 columns linked in series each of which are 2 m long with an internal diameter of 100 mm. The helium flow required is five times greater than the off-gas flow. The degree of purity for krypton is greater than 90% for a decontamination factor of greater than 1000. (orig./HP) [de

  7. A helium regenerative compressor

    Swift, W.L.; Nutt, W.E.; Sixsmith, H.

    1994-01-01

    This paper discusses the design and performance of a regenerative compressor that was developed primarily for use in cryogenic helium systems. The objectives for the development were to achieve acceptable efficiency in the machine using conventional motor and bearing technology while reducing the complexity of the system required to control contamination from the lubricants. A single stage compressor was built and tested. The compressor incorporates aerodynamically shaped blades on a 218 mm (8.6 inches) diameter impeller to achieve high efficiency. A gas-buffered non-contact shaft seal is used to oppose the diffusion of lubricant from the motor bearings into the cryogenic circuit. Since it is a rotating machine, the flow is continuous and steady, and the machine is very quiet. During performance testing with helium, the single stage machine has demonstrated a pressure ratio of 1.5 at a flow rate of 12 g/s with measured isothermal efficiencies in excess of 30%. This performance compares favorably with efficiencies generally achieved in oil flooded screw compressors

  8. The future of helium as a natural resource

    Glowacki, Bartek A; Nuttall, William J

    2012-01-01

    The book reveals the changing dynamics of the helium industry on both the supply-side and the demand-side. The helium industry has a long-term future and this important gas will have a role to play for many decades to come. Major new users of helium are expected to enter the market, especially in nuclear energy (both fission and fusion). Prices and volumes supplied and expected to rise and this will prompt greater efforts towards the development of new helium sources and helium conservation and recycling.

  9. Reactor helium system, design specification, operation and handling

    Badrljica, R.

    1984-06-01

    Apart from detailed design specification of the helium cover gas system of the Ra reactor, this document includes description of the operating regime, instructions for manipulations in the system with the aim of achieving and maintaining stationary gas circulation [sr

  10. Magnetotransport in a quasi-one-dimensional electron system over superfluid helium

    Nikolaenko, V A; Gladchenko, S P

    2002-01-01

    Magnetotransport in a nondegenerate quasi-one-dimensional electron system (Q1D) over superfluid helium is investigated experimentally. The experiments were carried out at perpendicular magnetic fields, B 0.9 K) and the electron-ripplon scattering (T 1(here omega sub c is the cyclotron frequency and t is the relaxation time of the electron system) agree qualitatively with the self-consistent Born approximation theory for a 2D electron system over helium. It is supposed that the quantitative discrepancies in the experimental and theoretical data are connected with different peculiar features of the investigated and analyzed electron systems. The experimental data on electron mobility at low temperatures and small magnetic fields coincide with the theoretical calculation made for the Q1D system. The negative magnetoresistance of the channels observed both in the electron-gas scattering and electron-ripplon scattering regions is supposed to be due to weak localization of carriers in the investigated electron syst...

  11. Effects of GC temperature and carrier gas flow rate on on-line oxygen isotope measurement as studied by on-column CO injection.

    Chen, Zhi-Gang; Yin, Xi-Jie; Zhou, Youping

    2015-08-01

    Although deemed important to δ 18 O measurement by on-line high-temperature conversion techniques, how the GC conditions affect δ 18 O measurement is rarely examined adequately. We therefore directly injected different volumes of CO or CO-N 2 mix onto the GC column by a six-port valve and examined the CO yield, CO peak shape, CO-N 2 separation, and δ 18 O value under different GC temperatures and carrier gas flow rates. The results show the CO peak area decreases when the carrier gas flow rate increases. The GC temperature has no effect on peak area. The peak width increases with the increase of CO injection volume but decreases with the increase of GC temperature and carrier gas flow rate. The peak intensity increases with the increase of GC temperature and CO injection volume but decreases with the increase of carrier gas flow rate. The peak separation time between N 2 and CO decreases with an increase of GC temperature and carrier gas flow rate. δ 18 O value decreases with the increase of CO injection volume (when half m/z 28 intensity is rate. On average, the δ 18 O value of the injected CO is about 1‰ higher than that of identical reference CO. The δ 18 O distribution pattern of the injected CO is probably a combined result of ion source nonlinearity and preferential loss of C 16 O or oxygen isotopic exchange between zeolite and CO. For practical application, a lower carrier gas flow rate is therefore recommended as it has the combined advantages of higher CO yield, better N 2 -CO separation, lower He consumption, and insignificant effect on δ 18 O value, while a higher-than-60 °C GC temperature and a larger-than-100 µl CO volume is also recommended. When no N 2 peak is expected, a higher GC temperature is recommended, and vice versa. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  12. Photoionization of helium dimers

    Havermeier, Tilo

    2010-01-01

    The helium dimer is one of the most weakly bound systems in the universe. This makes it an interesting quantum mechanical object for investigation. These Van der Waals Clusters can be produced in an expansion of a cryogenic gas jet through a small nozzle into vacuum. In the present experiment we examine the interaction of He dimers with synchrotron radiation at an energy range from 64 to 78 eV. We observed different pathways leading to single ionization of both He atoms of the dimer compound. This two close standing ions begin now to dissociate in cause of their coulomb potential. All charged fragments were detected in coincidence with a COLTRIMS system. Especially Interatomic Coulombic Decay (ICD) and the two step process (TS1) were clearly identified. Furthermore a distribution of the internuclear distance was obtained from the measured Kinetic Energy Release (KER). (orig.)

  13. Cryogenic helium gas convection research

    Donnelly, R.J.

    1994-10-01

    This is a report prepared by a group interested in doing research in thermal convection using the large scale refrigeration facilities available at the SSC Laboratories (SSCL). The group preparing this report consists of Michael McAshan at SSCL, Robert Behringer at Duke University, Katepalli Sreenivasan at Yale University, Xiao-Zhong Wu at Northern Illinois University and Russell Donnelly at the University of Oregon, who served as Editor for this report. This study reports the research and development opportunities in such a project, the technical requirements and feasibility of its construction and operation, and the costs associated with the needed facilities and support activities. The facility will be a unique national resource for studies of high-Reynolds-number and high-Rayleigh-number and high Rayleigh number turbulence phenomena, and is one of the six items determined as suitable for potential funding through a screening of Expressions of Interest. The proposed facility is possible only because of the advanced cryogenic technology available at the SSCL. Typical scientific issues to be addressed in the facility will be discussed. It devolved during our study, that while the main experiment is still considered to be the thermal convection experiment discussed in our original Expression of Interest, there are now a very substantial set of other, important and fundamental experiments which can be done with the large cryostat proposed for the convection experiment. We believe the facility could provide several decades of front-line research in turbulence, and shall describe why this is so

  14. Effects of helium impurities on superalloys

    Selle, J.E.

    1977-07-01

    A review of the literature on the effects of helium impurities on superalloys at elevated temperatures was undertaken. The actual effects of these impurities vary depending on the alloy, composition of the gas atmosphere, and temperature. In general, exposure in helium produces significant but not catastrophic changes in the structure and properties of the alloys. The effects of these treatments on the structure, creep, fatigue, and mechanical properties of the various alloys are reviewed and discussed. Suggestions for future work are presented

  15. Liquid helium target

    Fujii, Y.; Kitami, T.; Torikoshi, M.

    1984-12-01

    A liquid helium target system has been built and used for the experiment on the reaction 4 He(γ, p). The target system has worked satisfactorily; the consumption rate of liquid helium is 360 ml/h and the cryogenic system retains liquid helium for about ten hours. The structure, operation and performance of the target system are reported. (author)

  16. Separation of compressor oil from helium

    Strauss, R.; Perrotta, K.A.

    1982-01-01

    Compression of helium by an oil-sealed rorary screw compressor entrains as much as 4000 parts per million by weight of liquid and vapor oil impurities in the gas. The reduction below about 0.1 ppm for cryogenic applications is discussed. Oil seperation equipment designed for compressed air must be modified significantly to produce the desired results with helium. The main differences between air and helium filtration are described. A description of the coalescers is given with the continuous coalescing of liquid mist from air or other gas illustrated. Oil vapor in helium is discussed in terms of typical compressor oils, experimental procedure for measuring oil vapor concentration, measured volatile hydrocarbons in the lubricants, and calculated concentration of oil vapor in Helium. Liquid oil contamination in helium gas can be reduced well below 0.1 ppm by a properly designed multiple state coalescing filter system containing graded efficiency filter elements. The oil vapor problem is best attached by efficiently treating the oil to remove most of the colatiles before charging the compressor

  17. Blackbody-radiation correction to the polarizability of helium

    Puchalski, M.; Jentschura, U. D.; Mohr, P. J.

    2011-01-01

    The correction to the polarizability of helium due to blackbody radiation is calculated near room temperature. A precise theoretical determination of the blackbody radiation correction to the polarizability of helium is essential for dielectric gas thermometry and for the determination of the Boltzmann constant. We find that the correction, for not too high temperature, is roughly proportional to a modified hyperpolarizability (two-color hyperpolarizability), which is different from the ordinary hyperpolarizability of helium. Our explicit calculations provide a definite numerical result for the effect and indicate that the effect of blackbody radiation can be excluded as a limiting factor for dielectric gas thermometry using helium or argon.

  18. The effect of carrier gas flow rate and source cell temperature on low pressure organic vapor phase deposition simulation by direct simulation Monte Carlo method

    Wada, Takao; Ueda, Noriaki

    2013-01-01

    The process of low pressure organic vapor phase deposition (LP-OVPD) controls the growth of amorphous organic thin films, where the source gases (Alq3 molecule, etc.) are introduced into a hot wall reactor via an injection barrel using an inert carrier gas (N2 molecule). It is possible to control well the following substrate properties such as dopant concentration, deposition rate, and thickness uniformity of the thin film. In this paper, we present LP-OVPD simulation results using direct simulation Monte Carlo-Neutrals (Particle-PLUS neutral module) which is commercial software adopting direct simulation Monte Carlo method. By estimating properly the evaporation rate with experimental vaporization enthalpies, the calculated deposition rates on the substrate agree well with the experimental results that depend on carrier gas flow rate and source cell temperature. PMID:23674843

  19. The effect of carrier gas flow rate and source cell temperature on low pressure organic vapor phase deposition simulation by direct simulation Monte Carlo method

    Wada, Takao; Ueda, Noriaki

    2013-04-01

    The process of low pressure organic vapor phase deposition (LP-OVPD) controls the growth of amorphous organic thin films, where the source gases (Alq3 molecule, etc.) are introduced into a hot wall reactor via an injection barrel using an inert carrier gas (N2 molecule). It is possible to control well the following substrate properties such as dopant concentration, deposition rate, and thickness uniformity of the thin film. In this paper, we present LP-OVPD simulation results using direct simulation Monte Carlo-Neutrals (Particle-PLUS neutral module) which is commercial software adopting direct simulation Monte Carlo method. By estimating properly the evaporation rate with experimental vaporization enthalpies, the calculated deposition rates on the substrate agree well with the experimental results that depend on carrier gas flow rate and source cell temperature.

  20. Heat transfer in cryogenic helium gas by turbulent Rayleigh-Bénard convection in a cylindrical cell of aspect ratio 1

    Urban, Pavel; Hanzelka, Pavel; Musilová, Věra; Králík, Tomáš; La Mantia, M.; Srnka, Aleš; Skrbek, L.

    2014-01-01

    Roč. 16, č. 5 (2014), 053042: 1-40 ISSN 1367-2630 R&D Projects: GA ČR GPP203/12/P897 Institutional support: RVO:68081731 Keywords : Rayleigh-Bénard convection * heat transfer efficiency * cryogenic helium Subject RIV: BK - Fluid Dynamics Impact factor: 3.558, year: 2014

  1. Determination of hydrogen in zirconium and its alloys by melt extraction under carrier gas flow using thermal conductivity cell as detector

    Akhtar, J.; Ahmed, M.; Mohammad, B.; Jan, S.; Waqar, F.

    1987-06-01

    In the production of zirconium metal and its alloys the presence of hydrogen impurity affects mechanical and corrosion resistance properties of the product. Therefore, determination of hydrogen contents of the product is necessary. Conditions for its analysis by melt extraction under carrier gas stream using thermal conductivity cell as detector were studied and optimised. The method is capable of measuring hydrogen impurity in parts per million range. (author)

  2. High-temperature helium-loop facility

    Tokarz, R.D.

    1981-09-01

    The high-temperature helium loop is a facility for materials testing in ultrapure helium gas at high temperatures. The closed loop system is capable of recirculating high-purity helium or helium with controlled impurities. The gas loop maximum operating conditions are as follows: 300 psi pressure, 500 lb/h flow rate, and 2100 0 F temperature. The two test sections can accept samples up to 3.5 in. diameter and 5 ft long. The gas loop is fully instrumented to continuously monitor all parameters of loop operation as well as helium impurities. The loop is fully automated to operate continuously and requires only a daily servicing by a qualified operator to replenish recorder charts and helium makeup gas. Because of its versatility and high degree of parameter control, the helium loop is applicable to many types of materials research. This report describes the test apparatus, operating parameters, peripheral systems, and instrumentation system. The experimental capabilities and test conand presents the results that have been obtained. The study has been conducted using a four-phase approach. The first phase develops the solution to the steady-state radon-diffusion equation in one-dimensieered barriers; disposal charge analysis; analysis of spent fuel policy implementation; spent f water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps. Uranium concentrations in the sediments which were above detection limits ranged from 0.10 t 51.2 ppM. The mean of the logarithms of the uranium concentrations was 0.53. A group of high uranium concentrations occurs near the junctions of quadrangles AB, AC, BB, a 200 mK. In case 2), x-ray studies of isotopic phase separation in 3 He-- 4 He bcc solids were carried out by B. A. Fraass

  3. Gas and Pressure Dependence for the Mean Size of Nanoparticles Produced by Laser Ablation of Flowing Aerosols

    Nichols, William T.; Malyavanatham, Gokul; Henneke, Dale E.; Brock, James R.; Becker, Michael F.; Keto, John W.; Glicksman, Howard D.

    2000-01-01

    Silver nanoparticles were produced by laser ablation of a continuously flowing aerosol of microparticles entrained in argon, nitrogen and helium at a variety of gas pressures. Nanoparticles produced in this new, high-volume nanoparticle production technique are compared with our earlier experiments using laser ablation of static microparticles. Transmission electron micrographs of the samples show the nanoparticles to be spherical and highly non-agglomerated under all conditions tested. These micrographs were analyzed to determine the effect of carrier gas type and pressure on size distributions. We conclude that mean diameters can be controlled from 4 to 20 nm by the choice of gas type and pressure. The smallest nanoparticles were produced in helium, with mean sizes increasing with increasing molecular weight of the carrier gas. These results are discussed in terms of a model based on cooling via collisional interaction of the nanoparticles, produced in the laser exploded microparticle, with the ambient gas

  4. Mass spectrometric analysis of helium in stainless steel

    Isagawa, Hiroto; Wada, Yukio; Asakura, Yoshiro; Tsuji, Nobuo; Sato, Hitoshi; Tsutsumi, Kenichi

    1974-01-01

    Vacuum fusion mass-spectrometry was adopted for the analysis of helium in stainless steel. Samples were heated in a vacuum crucible, and helium in the samples was extracted and collected into a reservoir tank. The gas was then introduced through an orifice into a mass spectrometer, where the amount of helium was determined. The maspeq 070 quadrupole type mass spectrometer made by Shimazu Seisakusho, Ltd. was used. The resolving power was 150, and the mass range of the apparatus was 0-150. The determination limit of helium was about 2 x 10 -3 μg when standard helium gas was analyzed, and was about 10 -2 μg when the helium in stainless steel was analyzed. The relative standard deviation of helium intensity in repetitive measurement was about 2% in the amount of helium of 0.05 μg. Helium was injected into stainless steel by means of alpha particle irradiation with a cyclotron. The amount of helium in stainless steel was then determined. The energy of alpha particles was 34 MeV, and the beam area was 10 mm x 10 mm. The experimental data were higher than the expected value in one case, and were lower in the other case. This difference was attributable to the fluctuation of alpha particle beam, misplacement of sample plates, and unevenness of the alpha beam. (Fukutomi, T.)

  5. KSTAR Helium Refrigeration System Design and Manufacturing

    Dauguet, P.; Briend, P.; Abe, I.; Fauve, E.; Bernhardt, J.-M.; Andrieu, F.; Beauvisage, J.

    2006-01-01

    The tokamak developed in the KSTAR (Korean Superconducting Tokamak Advanced Research) project makes intensive use of superconducting magnets operated at 4.5 K. The cold components of the KSTAR tokamak require forced flow of supercritical helium for magnets/structure, boiling liquid helium for current leads, and gaseous helium for thermal shields. The cryogenic system will provide stable operation and full automatic control. A three-pressure helium cycle composed of six turbines has been customised design for this project. The '' design '' operating mode results with a system composed of a 9 kW refrigerator (including safety margin) and using gas and liquid storages for mass balancing. During Shot/Standby mode, the heat loads are highly time-dependent. A thermal damper is used to smooth these variations and will allow stable operation. (author)

  6. The study of the influence of helium on the counter's measurement properties

    Guan Rui; Weng Kuiping; Ren Xingbi

    2009-04-01

    In measurement of tritium by the proportional counter, methane is usually used as counter gas. Gas samples have been made with helium and methane in the proportion of concentration and measured to study the influence of helium on the counter's measurement properties. Then gas sample with tritium and helium has been measured, and the result is according with anticipation. The experiment has showed that the plateau curve of counter could be changed by helium, but the influence could be ignored when helium concentration less 10%. (authors)

  7. Cooling with Superfluid Helium

    Lebrun, P; Tavian, L [European Organization for Nuclear Research, Geneva (Switzerland)

    2014-07-01

    The technical properties of helium II (‘superfluid’ helium) are presented in view of its applications to the cooling of superconducting devices, particularly in particle accelerators. Cooling schemes are discussed in terms of heat transfer performance and limitations. Large-capacity refrigeration techniques below 2 K are reviewed, with regard to thermodynamic cycles as well as process machinery. Examples drawn from existing or planned projects illustrate the presentation. Keywords: superfluid helium, cryogenics.

  8. Helium leak and chemical impurities control technology in HTTR

    Tochio, Daisuke; Shimizu, Atsushi; Hamamoto, Shimpei; Sakaba, Nariaki

    2014-01-01

    Japan Atomic Energy Agency (JAEA) has designed and developed high-temperature gas-cooled reactor (HTGR) hydrogen cogeneration system named gas turbine high-temperature reactor (GTHTR300C) as a commercial HTGR. Helium gas is used as the primary coolant in HTGR. Helium gas is easy to leak, and the primary helium leakage should be controlled tightly from the viewpoint of preventing the release of radioactive materials to the environment. Moreover from the viewpoint of preventing the oxidization of graphite and metallic material, the helium coolant chemistry should be controlled tightly. The primary helium leakage and the helium coolant chemistry during the operation is the major factor in the HTGR for commercialization of HTGR system. This paper shows the design concept and the obtained operational experience on the primary helium leakage control and primary helium impurity control in the high-temperature engineering test reactor (HTTR) of JAEA. Moreover, the future plan to obtain operational experience of these controls for commercialization of HTGR system is shown. (author)

  9. Use of helium in uranium exploration, Grants district

    DeVoto, R.H.; Mead, R.H.; Martin, J.P.; Bergquist, L.E.

    1980-01-01

    The continuous generation of inert helium gas from uranium and its daughter products provides a potentially useful means for remote detection of uranium deposits. The practicality of conducting helium surveys in the atmosphere, soil gas, and ground water to explore for buried uranium deposits has been tested in the Grants district and in the Powder River Basin of Wyoming. No detectable helium anomalies related to buried or surface uranium deposits were found in the atmosphere. However, reproducible helium-in-soil-gas anomalies were detected spatially related to uranium deposits buried from 50 to 800 ft deep. Diurnal and atmospheric effects can cause helium content variations (noise) in soil gas that are as great as the anomalies observed from instantaneous soil-gas samples. Cumulative soil-gas helium analyses, such as those obtained from collecting undisturbed soil samples and degassing them in the laboratory, may reveal anomalies from 5 to 100 percent above background. Ground water samples from the Grants district, New Mexico, and the Powder River Basin, Wyoming, have distinctly anomalous helium values spatially related to buried uranium deposits. In the southern Powder River Basin, helium values 20 to 200 percent above background occur 2 to 18 mile down the ground-water flow path from known uranium roll-front deposits. In the Grants district, helium contents 40 to 700 percent above background levels are present in ground waters from the host sandstone in the vicinity of uranium deposits and from aquifers up to 3,000 ft stratigraphically above the deep uranium deposits. The use of helium in soil and ground-water surveys, along with uranium and radon analyses of the same materials, is strongly recommended is expensive, deep, uranium-exploration programs such as those being conducted in the Grants district

  10. Dipole moments of molecules solvated in helium nanodroplets

    Stiles, Paul L.; Nauta, Klaas; Miller, Roger E.

    2003-01-01

    Stark spectra are reported for hydrogen cyanide and cyanoacetylene solvated in helium nanodroplets. The goal of this study is to understand the influence of the helium solvent on measurements of the permanent electric dipole moment of a molecule. We find that the dipole moments of the helium solvated molecules, calculated assuming the electric field is the same as in vacuum, are slightly smaller than the well-known gas-phase dipole moments of HCN and HCCCN. A simple elliptical cavity model quantitatively accounts for this difference, which arises from the dipole-induced polarization of the helium

  11. Helium dilution refrigerator

    1973-01-01

    A new system of continuous heat exchange for a helium dilution refrigerator is proposed. The 3 He effluent tube is concurrent with the affluent mixed helium tube in a vertical downward direction. Heat exchange efficiency is enhanced by placing in series a number of elements with an enlarged surface area

  12. Helium localisation in tritides

    Flament, J.L.; Lozes, G.

    1982-06-01

    Study of titanium and LaNi 5 type alloys tritides lattice parameters evolution revealed that helium created by tritium decay remains in interstitial sites up to a limit material dependant concentration. Beyond this one exceeding helium precipites in voids [fr

  13. Sonic Helium Detectors in the Fermilab Tevatron

    Bossert, R. J.

    2006-04-01

    In the Fermilab Tevatron cryogenic system there are many remotely located low-pressure plate relief valves that must vent large volumes of cold helium gas when magnet quenches occur. These valves can occasionally stick open or not reseat completely, resulting in a large helium loss. As such, the need exists for a detector to monitor the relief valve's discharge area for the presence of helium. Due to the quantity needed, cost is an important factor. A unit has been developed and built for this purpose that is quite inexpensive. Its operating principle is based on the speed of sound, where two closely matched tubes operate at their acoustic resonant frequency. When helium is introduced into one of these tubes, the resulting difference in acoustic time of flight is used to trigger an alarm. At present, there are 39 of these units installed and operating in the Tevatron. They have detected many minor and major helium leaks, and have also been found useful in detecting a rise in the helium background in the enclosed refrigerator buildings. This paper covers the construction, usage and operational experience gained with these units over the last several years.

  14. Sonic helium detectors in the Fermilab Tevatron

    Bossert, R.J.; Fermilab

    2006-01-01

    In the Fermilab Tevatron cryogenic system there are many remotely located low-pressure plate relief valves that must vent large volumes of cold helium gas when magnet quenches occur. These valves can occasionally stick open or not reseat completely, resulting in a large helium loss. As such, the need exists for a detector to monitor the relief valve's discharge area for the presence of helium. Due to the quantity needed, cost is an important factor. A unit has been developed and built for this purpose that is quite inexpensive. Its operating principle is based on the speed of sound, where two closely matched tubes operate at their acoustic resonant frequency. When helium is introduced into one of these tubes, the resulting difference in acoustic time of flight is used to trigger an alarm. At present, there are 39 of these units installed and operating in the Tevatron. They have detected many minor and major helium leaks, and have also been found useful in detecting a rise in the helium background in the enclosed refrigerator buildings. This paper covers the construction, usage and operational experience gained with these units over the last several years

  15. Neutron-induced helium implantation in GCFR cladding

    Yamada, H.; Poeppel, R.B.; Sevy, R.H.

    1980-10-01

    The neutron-induced implantation of helium atoms on the exterior surfaces of the cladding of a prototypic gas-cooled fast reactor (GCFR) has been investigated analytically. A flux of recoil helium particles as high as 4.2 x 10 10 He/cm 2 .s at the cladding surface has been calculated at the peak power location in the core of a 300-MWe GCFR. The calculated profile of the helium implantation rates indicates that although some helium is implanted as deep as 20 μm, more than 99% of helium particles are implanted in the first 2-μm-deep layer below the cladding surface. Therefore, the implanted helium particles should mainly affect surface properties of the GCFR cladding

  16. Helium and radon-emanation bibliography. Selected references of geologic interest to uranium exploration

    Adkisson, C.W.; Reimer, G.M.

    1976-01-01

    Selected references on helium and radon gas emanations and geologically related topics are given. There are 172 references primarily related to helium geology, 129 to radon geology, and 171 to helium and radon. These references are of geologic interest to uranium exploration

  17. Measurement of ion beam angular distribution at different helium gas pressures in a plasma focus device by large-area polycarbonate detectors

    Sohrabi, M.; Habibi, M., E-mail: mortezahabibi@gmail.com; Ramezani, V. [Amirkabir University of Technology, Energy Engineering and Physics Department (Iran, Islamic Republic of)

    2017-02-15

    The paper presents an experimental study and analysis of full helium ion density angular distributions in a 4-kJ plasma focus device (PFD) at pressures of 10, 15, 25, and 30 mbar using large-area polycarbonate track detectors (PCTDs) (15-cm etchable diameter) processed by 50-Hz-HV electrochemical etching (ECE). Helium ion track distributions at different pressures, in particular, at the main axis of the PFD are presented. Maximum ion track density of ~4.4 × 10{sup 4} tracks/cm{sup 2} was obtained in the PCTD placed 6 cm from the anode. The ion distributions for all pressures applied are ring-shaped, which is possibly due to the hollow cylindrical copper anode used. The large-area PCTD processed by ECE proves, at the present state-of-theart, a superior method for direct observation and analysis of ion distributions at a glance with minimum efforts and time. Some observations of the ion density distributions at different pressures are reported and discussed.

  18. Effect of carburizing helium environment on creep behavior of Ni-base heat-resistant alloys for high-temperature gas-cooled reactors

    Kurata, Yuji; Ogawa, Yutaka; Nakajima, Hajime

    1988-01-01

    Creep tests were conducted on Ni-base heat-resistant alloys Hastelloy XR and XR-II, i.e. versions of Hastelloy X modified for nuclear applications, at 950degC using four types of helium environment with different impurity compositions, and mainly the effect of carburization was examined. For all the materials tested, the values of creep rupture time obtained under the carburizing conditions were similar to or longer than those in the commonly used, standard test environment (JAERI Type B helium). The difference among the results was interpreted by the counterbalancing effects of the strengthening due to carburization and possible weakening caused under very low oxidizing potential. In the corrosion monitoring specimens pronounced carbon pick-up was observed in the environment with high carbon activity and very low oxidizing potential. Based on the results obtained in the present and the previous works, it is suggested that a moderate control of the impurity chemistry is important rather than simple purification of the coolant in protecting the material from the environment-enhanced degradation. Either condition with high or low extremes in the oxidizing and carburizing potentials may cause enhanced degradation and thus are desirable to be avoided at the elevated temperatures. (author)

  19. Helium behaviour in implanted boron carbide

    Motte Vianney

    2015-01-01

    Full Text Available When boron carbide is used as a neutron absorber in nuclear power plants, large quantities of helium are produced. To simulate the gas behaviour, helium implantations were carried out in boron carbide. The samples were then annealed up to 1500 °C in order to observe the influence of temperature and duration of annealing. The determination of the helium diffusion coefficient was carried out using the 3He(d,p4He nuclear reaction (NRA method. From the evolution of the width of implanted 3He helium profiles (fluence 1 × 1015/cm2, 3 MeV corresponding to a maximum helium concentration of about 1020/cm3 as a function of annealing temperatures, an Arrhenius diagram was plotted and an apparent diffusion coefficient was deduced (Ea = 0.52 ± 0.11 eV/atom. The dynamic of helium clusters was observed by transmission electron microscopy (TEM of samples implanted with 1.5 × 1016/cm2, 2.8 to 3 MeV 4He ions, leading to an implanted slab about 1 μm wide with a maximum helium concentration of about 1021/cm3. After annealing at 900 °C and 1100 °C, small (5–20 nm flat oriented bubbles appeared in the grain, then at the grain boundaries. At 1500 °C, due to long-range diffusion, intra-granular bubbles were no longer observed; helium segregates at the grain boundaries, either as bubbles or inducing grain boundaries opening.

  20. Potential applications of high temperature helium

    Schleicher, R.W. Jr.; Kennedy, A.J.

    1992-09-01

    This paper discusses the DOE MHTGR-SC program's recent activity to improve the economics of the MHTGR without sacrificing safety performance and two potential applications of high temperature helium, the MHTGR gas turbine plant and a process heat application for methanol production from coal

  1. Parametric study of radiofrequency helium discharge under ...

    The excitation temperatures in the α and γ modes were 3266 and 4500 K respectively, evaluated by Boltzmann's plot method. The estimated gas temperature increased from 335 K in the α mode to 485 K in the γ mode, suggesting that the radio frequency atmospheric pressure helium discharge can be used for surface ...

  2. Measurement of OH density and air-helium mixture ratio in an atmospheric-pressure helium plasma jet

    Yonemori, Seiya; Ono, Ryo; Nakagawa, Yusuke; Oda, Tetsuji

    2012-01-01

    The absolute density of OH radicals in an atmospheric-pressure helium plasma jet is measured using laser-induced fluorescence (LIF). The plasma jet is generated in room air by applying a pulsed high voltage onto a quartz tube with helium gas flow. The time-averaged OH density is 0.10 ppm near the quartz tube nozzle, decreasing away from the nozzle. OH radicals are produced from water vapour in the helium flow, which is humidified by water adsorbed on the inner surface of the helium line and the quartz tube. When helium is artificially humidified using a water bubbler, the OH density increases with humidity and reaches 2.5 ppm when the water vapour content is 200 ppm. Two-dimensional distribution of air-helium mixture ratio in the plasma jet is also measured using the decay rate of the LIF signal waveform which is determined by the quenching rate of laser-excited OH radicals. (paper)

  3. Improvement of helium characteristics using argon in cylindrical ion source

    Abdel salam, F.W.; El-Khabeary, H.; Abdel reheem, A.M.; Kassem, N.E.; Ahmed, M.M.

    2004-01-01

    the discharge characteristics of pure helium gas were measured at different pressures in the range of 10 -4 torr. in order o improve its characteristics, argon gas was added . different percentages of argon gas ,1%,2%,3%,4%,5%,10% and 20% were used at constant values of pressures . Measurements of the efficiency of the cylindrical ion source in case of adding different percentages of argon gas to pure helium gas were made . an optimum value of the output ion beam current was obtained when 2% argon gas was added to pure helium gas . an output ion beam current of 105 μA was obtained at a pressure of 7X10 -4 torr inside the vacuum chamber and discharge current of 0.6 m A

  4. Investigation of impurity-helium solid phase decomposition

    Boltnev, R.E.; Gordon, E.B.; Krushinskaya, I.N.; Martynenko, M.V.; Pel'menev, A.A.; Popov, E.A.; Khmelenko, V.V.; Shestakov, A.F.

    1997-01-01

    The element composition of the impurity-helium solid phase (IHSP), grown by injecting helium gas jet, involving Ne, Ar, Kr, and Xe atoms and N 2 molecules, into superfluid helium, has been studied. The measured stoichiometric ratios, S = N H e / N I m, are well over the values expected from the model of frozen together monolayer helium clusters. The theoretical possibility for the freezing of two layers helium clusters is justified in the context of the model of IHSP helium subsystem, filled the space between rigid impurity centers. The process of decomposition of impurity-helium (IH)-samples taken out of liquid helium in the temperature range 1,5 - 12 K and the pressure range 10-500 Torr has been studied. It is found that there are two stages of samples decomposition: a slow stage characterized by sample self cooling and a fast one accompanied by heat release. These results suggest, that the IHSP consists of two types of helium - weakly bound and strongly bound helium - that can be assigned to the second and the first coordination helium spheres, respectively, formed around heavy impurity particles. A tendency for enhancement of IHSP thermo stability with increasing the impurity mass is observed. Increase of helium vapor pressure above the sample causes the improvement of IH sample stability. Upon destruction of IH samples, containing nitrogen atoms, a thermoluminescence induced by atom recombination has been detected in the temperature region 3-4,5 K. This suggests that numerous chemical reactions may be realized in solidified helium

  5. Study of low-defect and strain-relaxed GeSn growth via reduced pressure CVD in H2 and N2 carrier gas

    Margetis, J.; Mosleh, A.; Al-Kabi, S.; Ghetmiri, S. A.; Du, W.; Dou, W.; Benamara, M.; Li, B.; Mortazavi, M.; Naseem, H. A.; Yu, S.-Q.; Tolle, J.

    2017-04-01

    High quality, thick (up to 1.1 μm), strain relaxed GeSn alloys were grown on Ge-buffered Si (1 0 0) in an ASM Epsilon® chemical vapor deposition system using SnCl4 and low-cost commercial GeH4 precursors. The significance of surface chemistry in regards to growth rate and Sn-incorporation is discussed by comparing growth kinetics data in H2 and N2 carrier gas. The role of carrier gas is also explored in the suppression of Sn surface segregation and evolution of layer composition and strain profiles via secondary ion mass spectrometry and X-ray diffraction. Transmission electron microscopy revealed the spontaneous compositional splitting and formation of a thin intermediate layer in which dislocations are pinned. This intermediate layer enables the growth of a thick, strain relaxed, and defect-free epitaxial layer on its top. Last, we present photoluminescence results which indicate that both N2 and H2 growth methods produce optoelectronic device quality material.

  6. Phenomenological studies and modelling of the gaseous impurities oxidation and adsorption mechanisms in helium: application for the purification system optimization in gas cooled nuclear reactors

    Legros, F.

    2008-01-01

    In GEN IV studies on future fission nuclear reactors, two concepts using helium as a coolant have been selected: GFR and VHTR. Among radioactive impurities and dusts, helium can contain H 2 , CO, CH 4 , CO 2 , H 2 O, O 2 , as well as nitrogenous species. To optimize the reactor functioning and lifespan, it is necessary to control the coolant chemical composition using a dedicated purification system. A pilot designed at the CEA allows studying this purification system. Its design includes three unit operations: H 2 and CO oxidation on CuO, then two adsorption steps. This study aims at providing a detailed analysis of the first and second purification steps, which have both been widely studied experimentally at laboratory scale. A first modelling based on a macroscopic approach was developed to represent the behaviour of the reactor and has shown that the CuO fixed bed conversion is dependent on the chemistry (mass transfer is not an issue) and is complete. The results of the structural analysis of the solids allow considering the CuO as particles made of 200 nm diameter grains. Hence, a new model at grain scale is proposed. It is highlighted that the kinetic constants from these two models are related with a scale factor which depends on geometry. A competition between carbon monoxide and hydrogen oxidation has been shown. Activation energies are around 30 kJ.mol-1. Simulation of the simultaneous oxidations leads to consider CO preferential adsorption. A similar methodology has been applied for CO 2 and H 2 O adsorption. The experimental isotherms showed a Langmuir type adsorption. Using this model, experimental and theoretical results agree. (author) [fr

  7. Manufacturing cycle for pure neon-helium mixture production

    Batrakov, B.P.; Kravchenko, V.A.

    1980-01-01

    The manufacturing cycle for pure neon-helium mixture production with JA-300 nitrogen air distributing device has been developed. Gas mixture containing 2-3% of neon-helium mixture (the rest is mainly nitrogen 96-97%) is selected out of the cover of the JA-300 column condensator and enters the deflegmator under the 2.3-2.5 atm. pressure. The diflegmator presents a heat exchange apparatus in which at 78 K liquid nitrogen the condensation of nitrogen from the mixture of gases entering from the JA-300 column takes place. The enriched gas mixture containing 65-70% of neon-helium mixture and 30-35% of nitrogen goes out from the deflegmator. This enriched neon-helium mixture enters the gasgoeder for impure (65-70%) neon-helium mixture. Full cleaning of-neon helium mixture of nitrogen is performed by means of an adsorber. As adsorbent an activated coal has been used. Adsorption occurs at the 78 K temperature of liquid nitrogen and pressure P=0.1 atm. As activated coal cooled down to nitrogen temperature adsorbs nitrogen better than neon and helium, the nitrogen from the mixture is completely adsorbed. Pure neon-helium mixture from the adsorber comes into a separate gasgolder. In one campaign the cycle allows obtaining 2 m 3 of the mixture. The mixture contains 0.14% of nitrogen, 0.01% of oxygen and 0.06% of hydrogen

  8. Future of the gas industry. Energy carriers instead of power source?; Zukunft der Gaswirtschaft. Energietraeger statt Energiequelle?

    Bothe, David; Janssen, Matthias; Riechmann, Christoph [Frontier Economics, Koeln (Germany)

    2017-03-15

    For a long time, natural gas was considered as an ideal bridge technology for the energy transition because of the relatively low CO{sub 2} content. With increasing decarbonisation of electricity generation by renewable energies and the associated political vision of a far-reaching electrification of energy applications, in particular in the heat sector, the gas sector is, however, threatened to be overtaken by the renewables. This creates increasing uncertainty for business models and investments in the natural gas sector itself, but also potentially high macroeconomic costs of the energy transition. It can be shown that such a development is not unavoidable if the gas sector succeeds in using the existing possibilities cleverly. Thereby the continued use of existing gas infrastructure plays a central role. For use of the opportunities, however, a paradigm shift in politics, regulation and natural gas sector is necessary, whose key points are developed in this article. [German] Lange wurde Gas aufgrund des relativ geringen C0{sub 2}-Gehalts als ideale Brueckentechnologie fuer die Energiewende gehandelt. Mit zunehmender Dekarbonisierung der Stromerzeugung durch erneuerbare Energien und der damit verbundenen politischen Vision einer weitreichenden Elektrifizierung von Energieanwendungen insbesondere im Waermesektor droht die Gaswirtschaft allerdings von den Erneuerbaren ueberholt zu werden. Das schafft zunehmende Unsicherheit fuer Geschaeftsmodelle und Investitionen im Gassektor selbst, aber auch potenziell hohe gesamtwirtschaftliche Kosten der Energiewende. Es laesst sich zeigen, dass eine solche Entwicklung nicht unabwendbar ist, wenn es der Gaswirtschaft gelingt, die vorhandenen Moeglichkeiten clever zu nutzen. Dabei spielt der fortgesetzte Gebrauch der bereits vorhandenen Gasinfrastruktur die zentrale Rolle. Zur Nutzung der Chancen ist aber ein Paradigmenwechsel in Politik, Regulierung und Gaswirtschaft notwendig, dessen Eckpunkte in diesem Artikel entwickelt

  9. Raman Studies on Pre- and Post-Processed CVD Graphene Films Grown under Various Nitrogen Carrier Gas Flows

    Beh, K. P.; Yam, F. K.; Abdalrheem, Raed; Ng, Y. Z.; Suhaimi, F. H. A.; Lim, H. S.; Mat Jafri, M. Z.

    2018-04-01

    In this work, graphene films were grown on copper substrates using chemical vapour deposition method under various N2 carrier flow rate. The samples were characterized using Raman spectroscopy. Three sets of Raman measurements have been performed: graphene/Cu (as-grown samples), pre-annealed graphene/glass, and post-annealed graphene/glass. It was found that the Raman spectra of graphene/Cu samples possessed a hump-shaped baseline, additionally higher signal-to-noise ratio (SNR) that leads to attenuation graphene-related bands. Significant improvement of SNR and flat baseline were observed for graphene films transferred on glass substrate. Further analysis on the remaining sets of Raman spectra highlighted minute traces of polymethyl methacrylate (PMMA) could yield misleading results. Hence, the set of Raman spectra on annealed graphene/glass samples would be suitable in further elucidating the effects of N2 carrier flow towards graphene growth. From there, higher N2 flow implied dilution of methanol/H2 mixture, limiting interactions between reactants and substrate. This leads to smaller crystallite size and lesser graphene layers.

  10. Using the van der Waals broadening of spectral atomic lines to measure the gas temperature of an argon-helium microwave plasma at atmospheric pressure

    Munoz, J.; Dimitrijevic, M.S.; Yubero, C.; Calzada, M.D.

    2009-01-01

    The applications of plasmas generated with gas mixtures have become increasingly common in different scientific and technological fields. In order to understand the advantages of these discharges, for instance in chemical analysis, it is necessary to know the gas temperature (T g , kinetic energy of the heavy particles) since it has a great influence on the atomization reactions of the molecules located in the discharge, along with the dependence of the reaction rate on this parameter. The ro-vibrational emission spectra of the molecular species are usually used to measure the gas temperature of a discharge at atmospheric pressure although under some experimental conditions, these are difficult to detect. In such cases, the gas temperature can be determined from the van der Waals broadening of the emitted atomic spectral lines related to this parameter. The method proposed is based on the van der Waals broadening taking into account two perturbers

  11. Steady-state temperature distribution within a Brayton rotating unit operating in a power conversion system using helium-xenon gas

    Johnsen, R. L.; Namkoong, D.; Edkin, R. A.

    1971-01-01

    The Brayton rotating unit (BRU), consisting of a turbine, an alternator, and a compressor, was tested as part of a Brayton cycle power conversion system over a side range of steady state operating conditions. The working fluid in the system was a mixture of helium-xenon gases. Turbine inlet temperature was varied from 1200 to 1600 F, compressor inlet temperature from 60 to 120 F, compressor discharge pressure from 20 to 45 psia, rotative speed from 32 400 to 39 600 rpm, and alternator liquid-coolant flow rate from 0.01 to 0.27 pound per second. Test results indicated that the BRU internal temperatures were highly sensitive to alternator coolant flow below the design value of 0.12 pound per second but much less so at higher values. The armature winding temperature was not influenced significantly by turbine inlet temperature, but was sensitive, up to 20 F per kVA alternator output, to varying alternator output. When only the rotational speed was changed (+ or - 10% of rated value), the BRU internal temperatures varied directly with the speed.

  12. Suppressed carrier density for the patterned high mobility two-dimensional electron gas at γ-Al2O3/SrTiO3 heterointerfaces

    Niu, Wei; Gan, Yulin; Christensen, Dennis Valbjørn

    2017-01-01

    The two-dimensional electron gas (2DEG) at the non-isostructural interface between spinel γ-Al2O3 and perovskite SrTiO3 is featured by a record electron mobility among complex oxide interfaces in addition to a high carrier density up to the order of 1015 cm-2. Herein, we report on the patterning...... is found to be approximately 3×1013 cm-2, much lower than that of the unpatterned sample (~1015 cm-2). Remarkably, a high electron mobility of approximately 3,600 cm2V-1s-1 was obtained at low temperatures for the patterned 2DEG at a carrier density of ~ 7×1012 cm-2, which exhibits clear Shubnikov-de Hass...... quantum oscillations. The patterned high-mobility 2DEG at the γ-Al2O3/SrTiO3 interface paves the way for the design and application of spinel/perovskite interfaces for high-mobility all-oxide electronic devic...

  13. An efficient continuous flow helium cooling unit for Moessbauer experiments

    Herbert, I.R.; Campbell, S.J.

    1976-01-01

    A Moessbauer continuous flow cooling unit for use with liquid helium over the temperature range 4.2 to 300K is described. The cooling unit can be used for either absorber or source studies in the horizontal plane and it is positioned directly on top of a helium storage vessel. The helium transfer line forms an integral part of the cooling unit and feeds directly into the storage vessel so that helium losses are kept to the minimum. The helium consumption is 0.12 l h -1 at 4.2 K decreasing to 0.055 l h -1 at 40 K. The unit is top loading and the exchange gas cooled samples can be changed easily and quickly. (author)

  14. 33 CFR 165.110 - Safety and Security Zone; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston...

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety and Security Zone... Limited Access Areas First Coast Guard District § 165.110 Safety and Security Zone; Liquefied Natural Gas.... The following areas are safety and security zones: (1) Vessels underway. All navigable waters of the...

  15. Development of helium isotopic database in Japan

    Kusano, Tomohiro; Asamori, Koichi; Umeda, Koji

    2012-09-01

    We constructed “Helium Isotopic Database in Japan”, which includes isotope ratios of noble gases and chemical compositions of gas samples collected from hot springs and drinking water wells. The helium isotopes are excellent natural tracers for indicating the presence of mantle derived volatiles, because they are chemically inert and thus conserved in crustal rock-water systems. It is common knowledge that mantle degassing does not occur homogeneously over the Earth's surface. The 3 He/ 4 He ratios higher than the typical crustal values are interpreted to indicate that transfer of mantle volatiles into the crust by processes or mechanisms such as magmatic intrusion, faulting. In particular the spatial variation of helium isotope ratios could provide a valuable information to identify volcanic regions and tectonically active areas. The database was compiled geochemical data of hot spring gas etc. from 108 published papers. As a result of the data compiling, the database has 1728 helium isotopic data. A CD-ROM is attached as an appendix. (author)

  16. Gas and heat dynamics of a micro-scaled atmospheric pressure plasma reference jet

    Kelly, Seán; Golda, Judith; Schulz-von der Gathen, Volker; Turner, Miles M

    2015-01-01

    Gas and heat dynamics of the ‘Cooperation on Science and Technology (COST) Reference Microplasma Jet’ (COST-jet), a European lead reference device for low temperature atmospheric pressure plasma application, are investigated. Of particular interest to many biomedical application scenarios, the temperature characteristics of a surface impacted by the jet are revealed. Schlieren imaging, thermocouple measurements, infrared thermal imaging and numerical modelling are employed. Temperature spatial profiles in the gas domain reveal heating primarily of the helium fraction of the gas mixture. Thermocouple and model temporal data show a bounded exponential temperature growth described by a single characteristic time parameter to reach  ∼63% or (1-1/e) fraction of the temperature increase. Peak temperatures occurred in the gas domain where the carrier jet exits the COST-jet, with values ranging from ambient temperatures to in excess of 100 °C in ‘α-mode’ operation. In a horizontal orientation of the COST-jet a curved trajectory of the helium effluent at low gas flows results from buoyant forces. Gas mixture profiles reveal significant containment of the helium concentrations for a surface placed in close proximity to the COST-jet. Surface heating of a quartz plate follows a similar bounded exponential temporal temperature growth as device heating. Spatial profiles of surface heating are found to correlate strongly to the impacting effluent where peak temperatures occur in regions of maximum surface helium concentration. (paper)

  17. Gas and heat dynamics of a micro-scaled atmospheric pressure plasma reference jet

    Kelly, Seán; Golda, Judith; Turner, Miles M.; Schulz-von der Gathen, Volker

    2015-11-01

    Gas and heat dynamics of the ‘Cooperation on Science and Technology (COST) Reference Microplasma Jet’ (COST-jet), a European lead reference device for low temperature atmospheric pressure plasma application, are investigated. Of particular interest to many biomedical application scenarios, the temperature characteristics of a surface impacted by the jet are revealed. Schlieren imaging, thermocouple measurements, infrared thermal imaging and numerical modelling are employed. Temperature spatial profiles in the gas domain reveal heating primarily of the helium fraction of the gas mixture. Thermocouple and model temporal data show a bounded exponential temperature growth described by a single characteristic time parameter to reach  ∼63% or (1-1/e) fraction of the temperature increase. Peak temperatures occurred in the gas domain where the carrier jet exits the COST-jet, with values ranging from ambient temperatures to in excess of 100 °C in ‘α-mode’ operation. In a horizontal orientation of the COST-jet a curved trajectory of the helium effluent at low gas flows results from buoyant forces. Gas mixture profiles reveal significant containment of the helium concentrations for a surface placed in close proximity to the COST-jet. Surface heating of a quartz plate follows a similar bounded exponential temporal temperature growth as device heating. Spatial profiles of surface heating are found to correlate strongly to the impacting effluent where peak temperatures occur in regions of maximum surface helium concentration.

  18. Study of properties of helium-based gas mixtures for use of low momentum and high precision measurement in drift chambers

    Chen Chang; Zhang Qinjian; Ma Jimao; Huang Xiuping; Yi Kai; Zheng Shuchen

    1998-01-01

    Measured drift velocities using an uniform field drift chamber and multiplication factors obtained with proportional tubes in He-based gas mixtures He + CH 4 (80/20, 70/30) and He + iC 4 H 10 (85/15, 80/20, 70/30) are reported. The results are good agreement with calculations by Garfield Code. The Saturated drift velocity is V d ≅ 2.7 cm/μs and multiplication factor of M ≅ 10 4 -10 5 at certain working voltage is manageable in He/CH 4 (80/20) gas mixture, and it is good candidate of working gas for use of low momentum and high precision measurement in the drift chambers

  19. Spectroscopy of antiproton helium atoms

    Hayano, Ryugo

    2005-01-01

    Antiproton helium atom is three-body system consisting of an antiproton, electrons and a helium nucleus (denoted by the chemical symbol, p-bar H + ). The authors produced abundant atoms of p-bar 4 He + , and p-bar 3 He + in a cooled He gas target chamber stopping the p-bar beam decelerated to approximately 100 keV in the Antiproton Decelerator at CERN. A precision laser spectroscopy on the atomic transitions in the p-bar 4 He + , and in p-bar 3 He + was performed. Principle of laser spectroscopy and various modifications of the system to eliminate factors affecting the accuracy of the experiment were described. Deduced mass ratio of antiproton and proton, (|m p -bar - m p |)/m p reached to the accuracy of 10 ppb (10 -8 ) as of 2002, as adopted in the recent article of the Particle Data Group by P.J. Mohr and B.N. Taylor. This value is the highest precise data for the CPT invariance in baryon. In future, antihydrogen atoms will be produced in the same facility, and will provide far accurate value of antiproton mass thus enabling a better confirmation of CPT theorem in baryon. (T. Tamura)

  20. Magnetotransport in a quasi-one-dimensional electron system over superfluid helium

    Nikolaenko, V.A.; Kovdrya, Yu.Z.; Gladchenko, S.P.

    2002-01-01

    Magnetotransport in a nondegenerate quasi-one-dimensional electron system (Q1D) over superfluid helium is investigated experimentally. The experiments were carried out at perpendicular magnetic fields, B xx of the conducting channels mainly grows with increasing B for both the electron-gas atom scattering (T > 0.9 K) and the electron-ripplon scattering (T c τ>1(here ω c is the cyclotron frequency and t is the relaxation time of the electron system) agree qualitatively with the self-consistent Born approximation theory for a 2D electron system over helium. It is supposed that the quantitative discrepancies in the experimental and theoretical data are connected with different peculiar features of the investigated and analyzed electron systems. The experimental data on electron mobility at low temperatures and small magnetic fields coincide with the theoretical calculation made for the Q1D system. The negative magnetoresistance of the channels observed both in the electron-gas scattering and electron-ripplon scattering regions is supposed to be due to weak localization of carriers in the investigated electron system

  1. Gas chromatography of indium in macroscopic and carrier-free amounts using quartz and gold as stationary phases

    Serov, A.; Eichler, R.; Tuerler, A.; Wittwer, D.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab. fuer Radiochemie und Umweltchemie; Bern Univ. (Switzerland). Dept. fuer Chemie und Biochemie; Dressler, R.; Piguet, D.; Voegele, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab. fuer Radiochemie und Umweltchemie

    2011-07-01

    The chemical investigation of E113 is likely to become soon feasible. The determination of chemical properties of carrier-free amounts of the lighter homologues of element 113, especially indium and thallium, allows designing experimental set-ups and selecting experimental conditions suitable for performing these studies. Here, we present investigations of the interaction of indium species with quartz and gold surfaces. Deposition temperatures as well as enthalpies of adsorption were determined for indium T{sub dep} = 739 {+-} 20 C (-{delta}H{sub ads}(In) = 227 {+-} 10 kJ mol{sup -1}) and for indium hydroxide T{sub dep} = 250 {+-} 20 C (-{delta}H{sub ads}(InOH)= 124 {+-}10 kJ mol{sup -1}) respectively, on quartz. In case of adsorption of indium on a gold surface only a lower limit of the deposition temperature was established T{sub dep} > 980 C (-{delta}H{sub ads}(In) {>=} 315 {+-} 10 kJ mol{sup -1}). Investigations of macroscopic amounts of indium in thermosublimation experiments at similar experimental conditions were instrumental to establish a tentative speciation of the observed indium species. (orig.)

  2. Design and study of Engineering Test Facility - Helium Circulator

    Jiang Huijing; Ye Ping; Zhao Gang; Geng Yinan; Wang Jie

    2015-01-01

    Helium circulator is one of the key equipment of High-temperature Gas-cooled Reactor Pebble-bed Module (HTR-PM). In order to simulate most normal and accident operating conditions of helium circulator in HTR-PM, a full scale, rated flow rate and power, engineering test loop, which was called Engineering Test Facility - Helium Circulator (ETF-HC), was designed and established. Two prototypes of helium circulator, which was supported by Active Magnetic Bearing (AMB) or sealed by dry gas seals, would be tested on ETF-HC. Therefore, special interchangeable design was under consideration. ETF-HC was constructed compactly, which consisted of eleven sub-systems. In order to reduce the flow resistance of the circuit, special ducts, elbows, valves and flowmeters were selected. Two stages of heat exchange loops were designed and a helium - high pressure pure water heat exchanger was applied to ensure water wouldn't be vaporized while simulating accident conditions. Commissioning tests were carried out and operation results showed that ETF-HC meets the requirement of helium circulator operation. On this test facility, different kinds of experiments were supposed to be held, including mechanical and aerodynamic performance tests, durability tests and so on. These tests would provide the features and performance of helium circulator and verify its feasibility, availability and reliability. (author)

  3. Tungsten surface evolution by helium bubble nucleation, growth and rupture

    Sefta, Faiza; Wirth, Brian D.; Hammond, Karl D.; Juslin, Niklas

    2013-01-01

    Molecular dynamics simulations reveal sub-surface mechanisms likely involved in the initial formation of nanometre-sized ‘fuzz’ in tungsten exposed to low-energy helium plasmas. Helium clusters grow to over-pressurized bubbles as a result of repeated cycles of helium absorption and Frenkel pair formation. The self-interstitials either reach the surface as isolated adatoms or trap at the bubble periphery before organizing into prismatic 〈1 1 1〉 dislocation loops. Surface roughening occurs as single adatoms migrate to the surface, prismatic loops glide to the surface to form adatom islands, and ultimately as over-pressurized gas bubbles burst. (paper)

  4. New helium sniffing device for locating very fine leaks

    Murakami, Y.; Shimomura, Y.; Abe, T.; Obara, K.

    1984-01-01

    A new helium sniffing method for leak checking large vacuum vessels is described. The low sensitivity problem of the conventional helium sniffing method has been overcome by increasing the gas draw rate from around leaks into the detector up to about 0.1 Pa m 3 /s. The devised system consists of a flexible stainless steel capillary tube 0.6 mm i.d. and 10 m long, a sorption pump using molecular sieve, and a helium leak detector in series. This method is particularly useful for locating very fine leaks down to 10 -11 Pa m 3 /s. Relevant theoretical considerations and experimental results are presented

  5. Cyclotron production of radioactive gas from gaseous targets: inhomogeneity of the target activity - optimum flow rate of the carrier gas - cross sections

    Peters, J.-M.; Fiore, G. del; Quaglia, L.; Depresseux, J.-C.; Bartsch, P.

    1979-01-01

    When short-lived radioactive gases are produced by cyclotron-irradiated gaseous targets, the yield of activity, at the site of delivery, depends on the flow rate in the gas-carrying line. The authors improve a preliminarily published previous single model by the introduction of a supplementary hypothesis which takes into account the inhomogeneity of the activity in the gaseous target. By substituting the NTP volume of the gas in the irradiation cell Vsub(c) by a visible volume Vsub(a) depending on the flow rate and expressed by Vsub(a) = Vsub(infinity) +(V 0 - Vsub(infinity))exp(-kDsub(p)), they derive the following general expression for the optimum flow rate D which gives a maximum yield of production. D 2 -bD-bc-D 2 akexp(-kD)-abexp(-kD) = 0, a=lambda(V 0 -Vsub(infinity)), b = lambdaVsub(r), c = lambdaVsub(infinity), lambda = the decay constant of the radionuclide produced,Vsub(r) the inner volume of the gas-carrying line. The unknown parameters Vsub(r), Vsub(a), V 0 , Vsub(infinity), and k can be determined experimentally. The authors also suggest a new method for the determination of experimental cross sections with their gaseous target. (Auth.)

  6. Evaluation of US demo helium-cooled blanket options

    Wong, C.P.C.; McQuillan, B.W.; Schleicher, R.W.

    1995-10-01

    A He-V-Li blanket design was developed as a candidate for the U.S. fusion demonstration power plant. This paper presents an 18 MPa helium-cooled, lithium breeder, V-alloy design that can be coupled to the Brayton cycle with a gross efficiency of 46%. The critical issue of designing to high gas pressure and the compatibility between helium impurities and V-alloy are addressed

  7. Black-Body Radiation Correction to the Polarizability of Helium

    Puchalski, M.; Jentschura, U. D.; Mohr, P. J.

    2011-01-01

    The correction to the polarizability of helium due to black-body radiation is calculated near room temperature. A precise theoretical determination of the black-body radiation correction to the polarizability of helium is essential for dielectric gas thermometry and for the determination of the Boltzmann constant. We find that the correction, for not too high temperature, is roughly proportional to a modified hyperpolarizability (two-color hyperpolarizability), which is different from the ord...

  8. Studies of helium distribution in metal tritides

    Bowman, R.C. Jr.; Attalla, A.

    1976-01-01

    The distribution of helium ( 3 He) in LiT, TiT 2 , and UT 3 , which are regarded as representative metal tritides, was investigated using pulse nuclear magnetic resonance (NMR) techniques. Analyses of the NMR lineshapes and nuclear relaxation times indicate the 3 He atoms are trapped in microscopic gas bubbles for each tritide. The effects of concentration and temperature on the 3 He distributions were investigated as well

  9. Helium refrigerator for 'SULTAN'

    Arpagaus, M.; Erlach, H.; Quack, H.

    1984-01-01

    The authors describe the helium refrigerator designed for the SULTAN test facility. SULTAN (Supraleiter-Testanlage) is intended to serve for the developments and testing of high field superconducting magnets. These magnets are needed mainly for future applications in nuclear fusion. (Auth.)

  10. Cosmological helium production simplified

    Bernstein, J.; Brown, L.S.; Feinberg, G.

    1988-01-01

    We present a simplified model of helium synthesis in the early universe. The purpose of the model is to explain clearly the physical ideas relevant to the cosmological helium synthesis, in a manner that does not overlay these ideas with complex computer calculations. The model closely follows the standard calculation, except that it neglects the small effect of Fermi-Dirac statistics for the leptons. We also neglect the temperature difference between photons and neutrinos during the period in which neutrons and protons interconvert. These approximations allow us to express the neutron-proton conversion rates in a closed form, which agrees to 10% accuracy or better with the exact rates. Using these analytic expressions for the rates, we reduce the calculation of the neutron-proton ratio as a function of temperature to a simple numerical integral. We also estimate the effect of neutron decay on the helium abundance. Our result for this quantity agrees well with precise computer calculations. We use our semi-analytic formulas to determine how the predicted helium abundance varies with such parameters as the neutron life-time, the baryon to photon ratio, the number of neutrino species, and a possible electron-neutrino chemical potential. 19 refs., 1 fig., 1 tab

  11. Biomolecular ions in superfluid helium nanodroplets

    Gonzalez Florez, Ana Isabel

    2016-01-01

    The function of a biological molecule is closely related to its structure. As a result, understanding and predicting biomolecular structure has become the focus of an extensive field of research. However, the investigation of molecular structure can be hampered by two main difficulties: the inherent complications that may arise from studying biological molecules in their native environment, and the potential congestion of the experimental results as a consequence of the large number of degrees of freedom present in these molecules. In this work, a new experimental setup has been developed and established in order to overcome the afore mentioned limitations combining structure-sensitive gas-phase methods with superfluid helium droplets. First, biological molecules are ionised and brought into the gas phase, often referred to as a clean-room environment, where the species of interest are isolated from their surroundings and, thus, intermolecular interactions are absent. The mass-to-charge selected biomolecules are then embedded inside clusters of superfluid helium with an equilibrium temperature of ∝0.37 K. As a result, the internal energy of the molecules is lowered, thereby reducing the number of populated quantum states. Finally, the local hydrogen bonding patterns of the molecules are investigated by probing specific vibrational modes using the Fritz Haber Institute's free electron laser as a source of infrared radiation. Although the structure of a wide variety of molecules has been studied making use of the sub-Kelvin environment provided by superfluid helium droplets, the suitability of this method for the investigation of biological molecular ions was still unclear. However, the experimental results presented in this thesis demonstrate the applicability of this experimental approach in order to study the structure of intact, large biomolecular ions and the first vibrational spectrum of the protonated pentapeptide leu-enkephalin embedded in helium

  12. Biomolecular ions in superfluid helium nanodroplets

    Gonzalez Florez, Ana Isabel

    2016-07-01

    The function of a biological molecule is closely related to its structure. As a result, understanding and predicting biomolecular structure has become the focus of an extensive field of research. However, the investigation of molecular structure can be hampered by two main difficulties: the inherent complications that may arise from studying biological molecules in their native environment, and the potential congestion of the experimental results as a consequence of the large number of degrees of freedom present in these molecules. In this work, a new experimental setup has been developed and established in order to overcome the afore mentioned limitations combining structure-sensitive gas-phase methods with superfluid helium droplets. First, biological molecules are ionised and brought into the gas phase, often referred to as a clean-room environment, where the species of interest are isolated from their surroundings and, thus, intermolecular interactions are absent. The mass-to-charge selected biomolecules are then embedded inside clusters of superfluid helium with an equilibrium temperature of ∝0.37 K. As a result, the internal energy of the molecules is lowered, thereby reducing the number of populated quantum states. Finally, the local hydrogen bonding patterns of the molecules are investigated by probing specific vibrational modes using the Fritz Haber Institute's free electron laser as a source of infrared radiation. Although the structure of a wide variety of molecules has been studied making use of the sub-Kelvin environment provided by superfluid helium droplets, the suitability of this method for the investigation of biological molecular ions was still unclear. However, the experimental results presented in this thesis demonstrate the applicability of this experimental approach in order to study the structure of intact, large biomolecular ions and the first vibrational spectrum of the protonated pentapeptide leu-enkephalin embedded in helium

  13. Production and correlation of reactive oxygen and nitrogen species in gas- and liquid-phase generated by helium plasma jets under different pulse widths

    Liu, Zhijie; Zhou, Chunxi; Liu, Dingxin; Xu, Dehui; Xia, Wenjie; Cui, Qingjie; Wang, Bingchuan; Kong, Michael G.

    2018-01-01

    In this paper, we present the effects of the pulse width (PW) on the plasma jet's discharge characteristics, particularly focusing on the production and correlation of the reactive oxygen and nitrogen species (RONS) in gas- and liquid-phase. It is found that the length of plasma jet plume first increases before the PW of 10 μs, then gradually decreases and finally almost remains unchanged beyond 150 μs. The plasma bullet disappears after the falling edge of the voltage pulse at low PW, while it terminates far ahead of the falling edge of voltage pulse at high PW. This is mainly attributed to accumulation of space charges that lead to weakening of the reduced electric field with an increase of PW from low to high. More important, it is found that the excited reactive species, the positive and negative ions from plasma jet, and the concentrations of NO2- and NO3- in deionized water exposed to plasma jet also display the first increasing and then decreasing change trend with increase of PW, while the concentration of H2O2 in water almost displays the linearly increasing trend. This mainly results from the formation of the H3O+ and HO2-, as well as their ion water clusters that can produce more OH radicals to be converted into H2O2, while the NO2- and NO3- in gas phase can transport into water and exist most stably in water. The water cluster formation at gas-liquid interface is an important key process that can affect the chemical nature and dose of aqueous RONS in water; this is beneficial for understanding how the RONS are formed in liquid-phase.

  14. High-temperature helium embrittlement (T>=0,45Tsub(M)) of metals

    Batfalsky, P.

    1984-06-01

    High temperature helium embrittlement, swelling and irradiation creep are the main technical problem of fusion reactor materials. The expected helium production will be very high. The helium produced by (n,α)-processes precipitates into helium bubbles because its solubility in solid metals is very low. Under continuous helium production at high temperature and stress the helium bubbles grow and lead to intergranular early failure. Solution annealed foil specimens of austenitic stainless steel AISI 316 were implanted with α-particles: 1. during creep tests at 1023 K (''in-beam'' test) 2. before the creep tests at high temperature (1023 K). The creep tests have been performed within large ranges of test parameter, e.g. applied stress, temperature, helium implantation rate and helium concentration. After the creep tests the microstructure was investigated using scanning (SEM) and transmission (TEM) electron microscopy. All the helium implanted specimens showed high temperature helium embrittlement, i.e. reduction of rupture time tsub(R) and ductility epsilonsub(R) and evidence of intergranular brittle fracture. The ''in-beam'' creep tests showed greater reduction of rupture time tsub(R) and ductility than the preimplanted creep tests. The comparison of this experimentally obtained data with various theoretical models of high temperature helium embrittlement showed that within the investigated parameter ranges the mechanism controlling the life time of the samples is probably the gas driven stable growth of the helium bubbles within the grain boundaries. (orig.)

  15. Diffusion of helium in the Sun

    Noerdlinger, P D [Michigan State Univ., East Lansing (USA). Dept. of Astronomy and Astrophysics; Amsterdam Univ. (Netherlands). Sterrenkundig Instituut)

    1977-05-01

    I have reduced the set of diffusion and flow equations developed by Burgers for a multi-component gas to a workable scheme for the actual evaluation of the relative diffusion of hydrogen and helium in stars. Previous analyses have used the Aller and Chapman equations, which apply only to trace constitutents and whose coefficients are not believed to be as accurate as Burgers'. Furthermore, the resulting equations have been combined consistently with Paczynski's stellar evolution code to demonstrate small but significant effects in the Sun, from the thermal and gravitational settling of Helium. The core helium content of a 1 M star goes up about 0.04 and the surface helium content down by about -0.03 in 4.5 10/sup 9/ years. The results are still somewhat uncertain because of uncertainties in the underlying plasma physics, and further research is suggested. In any case, the diffusion process speeds up with time, due to increased temperature gradient, and it will be of interest to follow the process in older stars and in later stellar evolution.

  16. Mixed helium-3 - helium-4 calorimeter. Very low temperature calorimetry; Calorimetre mixte a helium-3 et helium-4. Calorimetrie a tres basse temperature

    Testard, O [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-06-01

    A description is given of a double-racket calorimeter using helium-4 and helium-3 as the cryogenic fluids and making it possible to vary the temperature continuously from 0.35 K to 4.2 K. By using an electric thermal regulator together with liquid hydrogen it is possible to extend this range up to about 30 K. In the second part, a review is made of the various, methods available for measuring specific heats. The method actually used in the apparatus previously described is described in detail. The difficulties arising from the use of an exchange gas for the thermal contact have been solved by the use of adsorption pumps. (author) [French] On decrit un calorimetre a double enceinte utilisant comme fluide cryogenique l'helium-4 et l'helium-3 et permettant de varier continuement la temperature de 0,35 K a 4,2 K. L'utilisation d'un regulateur thermique electrique ainsi que celle d'hydrogene, liquide permettent d'etendre cette gamme jusqu'a 30 K environ. Dans une deuxieme partie, on passe en revue les diverses methodes de mesure des chaleurs specifiques. La methode concrete utilisee dans l'appareil precedemment decrit est exposee en detail. Les difficultes inherentes a l'utilisation de gaz d'echange comme agent de contact thermique ont ete levees par la mise en oeuvre de pompes a adsorbant. (auteur)

  17. Studies of matrix diffusion in gas phase

    Hartikainen, K.; Timonen, J.; Vaeaetaeinen, K.; Pietarila, H.

    1994-03-01

    The diffusion of solutes from fractures into rock matrix is an important factor in the safety analysis of disposal of radioactive waste. Laboratory measurements are needed to complement field investigations for a reliable determination of the necessary transport parameters. Measurements of diffusion coefficients in tight rock samples are usually time consuming because the diffusion processes are slow. On the other hand it is well known that diffusion coefficients in the gas phase are roughly four orders of magnitude larger than those in the liquid phase. Therefore, for samples whose structures do not change much upon drying, it is possible to estimate the diffusion properties of the liquid phase when the properties of the gas phase are known. Advantages of the gas method are quick and easy measurements. In the measurements nitrogen was used as the carrier gas and helium as the tracer gas, and standard techniques have been used for helium detection. Techniques have been developed for both channel flow and through-diffusion measurements. The breakthrough curves have been measured in every experiment and all measurements have been modelled by using appropriate analytical models. As a result matrix porosities and effective diffusion coefficients in the gas phase have been determined. (12 refs., 21 figs., 6 tabs.)

  18. Conductivity change of defective graphene by helium ion beams

    Yuichi Naitou

    2017-04-01

    Full Text Available Applying a recently developed helium ion microscope, we demonstrated direct nano-patterning and Anderson localization of single-layer graphene (SLG on SiO2/Si substrates. In this study, we clarified the spatial-resolution-limitation factor of direct nano-patterning of SLG. Analysis of scanning capacitance microscopy measurements reveals that the conductivity of helium ion (H+-irradiated SLG nanostructures depends on their geometrical size, i.e., the smaller the H+-irradiated SLG region, the higher its conductivity becomes. This finding can be explained by the hopping carrier transport across strongly localized states of defective SLG.

  19. Performance of the Helium Circulation System on a Commercialized MEG

    Takeda, T; Miyazaki, T; Okamoto, M; Katagiri, K

    2012-01-01

    We report the performance of a helium circulation system (HCS) mounted on a MEG (Magnetoencephalography) at Nagoya University, Japan. This instrument is the first commercialized version of an HCS. The HCS collects warm helium gas at approximately 300 K and then cools it to approximately 40 K. The gas is returned to the neck tube of a Dewar of the MEG to keep it cold. It also collects helium gas in the region just above the liquid helium surface while it is still cold, re-liquefies the gas and returns it to the Dewar. A special transfer tube (TT) of approximately 3 m length was developed to allow for dual helium streams. This tube separates the HCS using a MEG to reduce magnetic noise. A refiner was incorporated to effectively collect contaminating gases by freezing them. The refiner was equipped with an electric heater to remove the frozen contaminants as gases into the air. A gas flow controller was also developed, which automatically controlled the heater and electric valves to clean up contamination. The developed TT exhibited a very low heat inflow of less than 0.1 W/m to the liquid helium, ensuring efficient operation. The insert tube diameter, which was 1.5 in. was reduced to a standard 0.5 in. size. This dimensional change enabled the HCS to mount onto any commercialized MEG without any modifications to the MEG. The HCS can increase liquid helium in the Dewar by at least 3 liters/Day using two GM cryocoolers (SRDK-415D, Sumitomo Heavy Industries, Ltd.). The noise levels were virtually the same as before this installation.

  20. Hot helium flow test facility summary report

    1980-06-01

    This report summarizes the results of a study conducted to assess the feasibility and cost of modifying an existing circulator test facility (CTF) at General Atomic Company (GA). The CTF originally was built to test the Delmarva Power and Light Co. steam-driven circulator. This circulator, as modified, could provide a source of hot, pressurized helium for high-temperature gas-cooled reactor (HTGR) and gas-cooled fast breeder reactor (GCFR) component testing. To achieve this purpose, a high-temperature impeller would be installed on the existing machine. The projected range of tests which could be conducted for the project is also presented, along with corresponding cost considerations

  1. Analysis of trace levels of impurities and hydrogen isotopes in helium purge gas using gas chromatography for tritium extraction system of an Indian lead lithium ceramic breeder test blanket module.

    Devi, V Gayathri; Sircar, Amit; Yadav, Deepak; Parmar, Jayraj

    2018-01-12

    In the fusion fuel cycle, the accurate analysis and understanding of the chemical composition of any gas mixture is of great importance for the efficient design of a tritium extraction and purification system or any tritium handling system. Methods like laser Raman spectroscopy and gas chromatography with thermal conductivity detector have been considered for hydrogen isotopes analyses in fuel cycles. Gas chromatography with a cryogenic separation column has been used for the analysis of hydrogen isotopes gas mixtures in general due to its high reliability and ease of operation. Hydrogen isotopes gas mixture analysis with cryogenic columns has been reported earlier using different column materials for percentage level composition. In the present work, trace levels of hydrogen isotopes (∼100 ppm of H 2 and D 2 ) have been analyzed with a Zeolite 5A and a modified γ-Al 2 O 3 column. Impurities in He gas (∼10 ppm of H 2 , O 2 , and N 2 ) have been analyzed using a Zeolite 13-X column. Gas chromatography with discharge ionization detection has been utilized for this purpose. The results of these experiments suggest that the columns developed were able to separate ppm levels of the desired components with a small response time (<6 min) and good resolution in both cases. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Influence of the carrier Gas, trimethylgallium flow, and growth time on the character of the selective epitaxy of GaN

    Rozhavskaya, M. M., E-mail: MRozhavskaya@gmail.com; Lundin, V. V.; Zavarin, E. E.; Troshkov, S. I.; Brunkov, P. N.; Tsatsulnikov, A. F. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2013-03-15

    The influence of the carrier gas, trimethylgallium flow, and growth time on the character of the selective epitaxy of GaN in stripe windows oriented along the crystallographic direction Left-Pointing-Angle-Bracket 11-bar00 Right-Pointing-Angle-Bracket GaN for various widths of the mask between the stripes is studied. It is shown that the addition of nitrogen in the reactor atmosphere leads to changes in the form of the stripes in the case of wide (40 {mu}m) mask from a rectangular form restricted by a {l_brace}1 1-bar20{r_brace} lateral face to a trapezoidal form restricted by a {l_brace}1 1-bar22{r_brace} lateral face. It is also shown that during growth in the nitrogen-hydrogen mixture, the gallium flow starts to considerably affect the form of the growing stripes. It is shown that the process is significantly unstable, which leads to a noticeable variation in the form type as the transverse section of the stripe increases.

  3. Neutral helium beam probe

    Karim, Rezwanul

    1999-10-01

    This article discusses the development of a code where diagnostic neutral helium beam can be used as a probe. The code solves numerically the evolution of the population densities of helium atoms at their several different energy levels as the beam propagates through the plasma. The collisional radiative model has been utilized in this numerical calculation. The spatial dependence of the metastable states of neutral helium atom, as obtained in this numerical analysis, offers a possible diagnostic tool for tokamak plasma. The spatial evolution for several hypothetical plasma conditions was tested. Simulation routines were also run with the plasma parameters (density and temperature profiles) similar to a shot in the Princeton beta experiment modified (PBX-M) tokamak and a shot in Tokamak Fusion Test Reactor tokamak. A comparison between the simulation result and the experimentally obtained data (for each of these two shots) is presented. A good correlation in such comparisons for a number of such shots can establish the accurateness and usefulness of this probe. The result can possibly be extended for other plasma machines and for various plasma conditions in those machines.

  4. Antiprotonic helium atomcules

    Sauge Sébastien

    2012-10-01

    Full Text Available About 3% of antiprotons ( stopped in helium are long-lived with microsecond lifetimes, against picoseconds in all other materials. This unusual longevity has been ascribed to the trapping of on metastable bound states in He+ helium atom-molecules thus named atomcules. Apart from their unique dual structure investigated by laser spectroscopy – a near-circular quasi-classical Rydberg atom with l ~ n – 1 ~ 37 or a special diatomic molecule with a negatively charged nucleus in high rotational state with J = l – the chemical physics aspects of their interaction with other atoms or molecules constitute an interesting topic for molecular physics. While atomcules may resist to million collisions in helium, molecular contaminants such as H2 are likely to destroy them in a single one, down to very low temperatures. In the Born-Oppenheimer framework, we interpret the molecular interaction obtained by ab initio quantum chemical calculations in terms of classical reactive channels, with activation barriers accounting for the experiments carried out in He and H2. From classical trajectory Monte Carlo simulations, we show that the thermalization stage strongly quenches initial populations, thus reduced to a recovered 3 % trapping fraction. This work illustrates the pertinence of chemical physics concepts to the study of exotic processes involving antimatter. New insights into the physico-chemistry of cold interstellar radicals are anticipated.

  5. Technique to eliminate helium induced weld cracking in stainless steels

    Chin-An Wang; Chin, B.A.

    1992-01-01

    Experiments have shown that Type 316 stainless steel is susceptible to heat-affected-zone (HAZ) cracking upon cooling when welded using the gas tungsten arc (GTA) process under lateral constraint. The cracking has been hypothesized to be caused by stress-assisted helium bubble growth and rupture at grain boundaries. This study utilized an experimental welding setup which enabled different compressive stresses to be applied to the plates during welding. Autogenous GTA welds were produced in Type 316 stainless steel doped with 256 appm helium. The application of a compressive stress, 55 Mpa, during welding suppressed the previously observed catastrophic cracking. Detailed examinations conducted after welding showed a dramatic change in helium bubble morphology. Grain boundary bubble growth along directions parallel to the weld was suppressed. Results suggest that stress-modified welding techniques may be used to suppress or eliminate helium-induced cracking during joining of irradiated materials

  6. Installation and Commissioning of the Helium Refrigeration System for the HANARO-CNS

    Choi, Jung Woon; Kim, Young Ki; Wu, Sang Ik; Son, Woo Jung

    2009-11-01

    The cold neutron source (CNS), which will be installed in the vertical CN hole of the reflector tank at HANARO, makes thermal neutrons to moderate into the cold neutrons with the ranges of 0.1 ∼ 10 meV passing through a moderator at about 22K. A moderator to produce cold neutrons is liquid hydrogen, which liquefies by the heat transfer with cryogenic helium flowing from the helium refrigeration system. For the maintenance of liquid hydrogen in the IPA, the CNS system is mainly consisted of the hydrogen system to supply the hydrogen to the IPA, the vacuum system to keep the cryogenic liquid hydrogen in the IPA, and the helium refrigeration system to liquefy the hydrogen gas. The helium refrigeration system can be divided into two sections: one is the helium compression part from the low pressure gas to the high pressure gas and the other is the helium expansion part from the high temperature gas and pressure to low temperature and pressure gas by the expansion turbine. The helium refrigeration system except the warm helium pipe and the helium buffer tank has been manufactured by Linde Kryotechnik, AG in Switzerland and installed in the research reactor hall, HANARO. Other components have been manufactured in the domestic company. This technical report deals with the issues, its solutions, and other particular points while the helium refrigeration system was installed at site, verified its performance, and conducted its commissioning along the reactor operation. Furthermore, the operation procedure of the helium refrigeration system is included in here for the normal operation of the CNS

  7. Surface electrons of helium films

    Studart, N.; Hipolito, O.

    1986-01-01

    Theoretical calculations of some properties of two-dimensional electrons on a liquid helium film adsorbed on a solid substrate are reviewed. We describe the spectrum of electron bound states on bulk helium as well on helium films. The correlational properties, such as the structure factor and correlation energy, are determined as functions of the film thickness for different types of substrates in the framework of a Generalized Random-Phase Approximation. The collective excitations of this system are also described. The results for electrons on the surface of thin films and bulk helium are easily obtained. we examine the electron interaction with the excitations of the liquid helium surface resulting in a new polaron state, which was observed very recently. The ground state energy and the effective mass of this polaron are determined by using the path-integral formalism and unitary-transformation method. Recent speculations about the phase diagram of electrons on the helium film are also discussed. (Author) [pt

  8. Radionuclide carrier

    Hartman, F.A.; Kretschmar, H.C.; Tofe, A.J.

    1978-01-01

    A physiologically acceptable particulate radionuclide carrier is described. It comprises a modified anionic starch derivative with 0.1% to 1.5% by weight of a reducing agent and 1 to 20% by weight of anionic substituents

  9. Carrier Screening

    ... How accurate is carrier screening? No test is perfect. In a small number of cases, test results ... in which an egg is removed from a woman’s ovary, fertilized in a laboratory with the man’s ...

  10. Helium ion damage in an amorphous Fe-Ni-Mo-B alloy

    Swijgenhoven, H. van; Stals, L.M.; Knuyt, G.

    1983-01-01

    Data are presented on helium gas bubble and helium blister formation for Metglas 2826MB during 5 keV He + -implantation in the temperature range 200K-600K and dose range 5.10 20 -10 22 He + /m 2 . It is concluded that amorphous alloys are less radiation resistant as has been thought earlier. (author)

  11. Orion A helium abundance

    Tsivilev, A.P.; Ershov, A.A.; Smirnov, G.T.; Sorochenko, R.L.

    1986-01-01

    The 22.4-GHz (H,He)66-alpha and 36.5-GHz (H,He)56-alpha radio recombination lines have been observed at several Jaffe-Pankonin positions in the central part of the Orion A source. The measured relative abundance of ionized helium increases with distance, averaging 11.6 percent at peripheral points. The observed behavior is interpreted by a blister-type model nebula, which implies that Orion A has a true He abundance of 12 percent, is moving with a radial velocity of 5 km/sec, and is expanding. 18 references

  12. Simulation of liquid helium

    Ceperley, D.M.

    1985-07-01

    The author discusses simulation methods for quantum mechanical systems at finite temperatures. Recently it has been shown that static properties of some quantum systems can be obtained by simulation in a straightforward manner using path integrals, albeit with an order of magnitude more computing effort needed than for the corresponding classical systems. Some dynamical information can be gleaned from these simulations as will be discussed below. But this is very limited - there is no quantum version of the molecular dynamics method. The path integral method is illustrated by discussing the application to liquid helium. 12 refs., 8 figs

  13. Equation of state of fluid helium at high temperatures and densities

    Cai, Lingcang; Chen, Qifeng; Gu, Yunjun; Zhang, Ying; Zhou, Xianming; Jing, Fuqian

    2005-03-01

    Hugoniot curves and shock temperatures of gas helium with initial temperature 293 K and three initial pressures 0.6, 1.2, and 5.0 MPa were measured up to 15000 K using a two-stage light-gas gun and transient radiation pyrometer. It was found that the calculated Hugoniot EOS of gas helium at the same initial pressure using Saha equation with Debye-Hückel correction was in good agreement with the experimental data. The curve of the calculated shock wave velocity with the particle velocity of gas helium which is shocked from the initial pressure 5 MPa and temperature 293 K, i.e., the D ≈ u relation, D= C 0+λ u ( uionization degree of the shocked gas helium reaches 10-3.

  14. Design concept of cryogenic falling liquid film helium separator

    Kinoshita, M.; Yamanishi, T.; Bartlit, J.R.; Sherman, R.H.

    1986-01-01

    A design concept is developed for a cryogenic falling liquid film helium separator by clarifying the differences between this process and a cryogenic distillation column. The process characteristics are greatly improved by the idea of adding an H 2 gas flow to a point near the upper end of the packed section. The flow rate of tritium lost from the top is kept extremely low with an adequately short packed section, and the column pressure is reduced to 1 atm. The addition causes no appreciable increase in the protium percentage (approx. =1%) in the bottom liquid flow. A design procedure applying the Colburn-Hougen method is proposed for determining specifications of the refrigerated section. It is shown that the presence of noncondensible helium requires a significantly larger heat transfer area mainly because the mass transfer resistance increases enormously as the condensation of hydrogen isotopes proceeds. Control schemes are also proposed: The tritium concentration in the top gas is controlled by the H 2 gas flow rate. The pressure rise caused by an increase of the helium percentage within the refrigerated section, which cannot readily be eliminated by changing input specifications of the refrigerant gas, is avoided by increasing the top gas flow rate to release more helium from the top

  15. Recent progress in developments of membrane materials and modification techniques for high performance helium separation and recovery : a review

    Soleimany, A.; Hosseini, S.S.; Gallucci, F.

    2017-01-01

    Helium is a valuable gas with unique properties and applications and still the prominent industrial source of helium is natural gas. Because of several advantages of membrane-based separation processes over conventional methods as well as the lack of a comprehensive scientific report, the present

  16. High Efficiency Regenerative Helium Compressor, Phase I

    National Aeronautics and Space Administration — Helium plays several critical rolls in spacecraft propulsion. High pressure helium is commonly used to pressurize propellant fuel tanks. Helium cryocoolers can be...

  17. Supersonic jets of hydrogen and helium for laser wakefield acceleration

    Svensson, K.; Wojda, F.; Senje, L.; Burza, M.; Aurand, B.; Genoud, G.; Persson, A.; Wahlström, C.-G.; Lundh, O.

    2016-01-01

    The properties of laser wakefield accelerated electrons in supersonic gas flows of hydrogen and helium are investigated. At identical backing pressure, we find that electron beams emerging from helium show large variations in their spectral and spatial distributions, whereas electron beams accelerated in hydrogen plasmas show a higher degree of reproducibility. In an experimental investigation of the relation between neutral gas density and backing pressure, it is found that the resulting number density for helium is ∼30% higher than for hydrogen at the same backing pressure. The observed differences in electron beam properties between the two gases can thus be explained by differences in plasma electron density. This interpretation is verified by repeating the laser wakefield acceleration experiment using similar plasma electron densities for the two gases, which then yielded electron beams with similar properties.

  18. An optimum cold end configuration for helium liquefaction cycles

    Minta, M.; Smith, J.L.

    1984-01-01

    This chapter examines the effect of the non-ideal behavior of helium at low temperature on the performance of helium liquefaction cycles. The effect is isolated by means of a continuum model for the precooling stage. The cold end losses are due primarily to the composite effect of the non-ideality of helium at low temperatures and the heat exchanger losses, in addition to the component losses fixed by the expander/compressor efficiencies. Topics considered include continuously distributed full-pressure ratio expanders, continuously distributed full-flow expanders, the heat exchange effect (ideal gas working fluid, real gas working fluid), and cold end configuration. The cold end configuration minimizes the cycle cold end losses

  19. Supersonic jets of hydrogen and helium for laser wakefield acceleration

    K. Svensson

    2016-05-01

    Full Text Available The properties of laser wakefield accelerated electrons in supersonic gas flows of hydrogen and helium are investigated. At identical backing pressure, we find that electron beams emerging from helium show large variations in their spectral and spatial distributions, whereas electron beams accelerated in hydrogen plasmas show a higher degree of reproducibility. In an experimental investigation of the relation between neutral gas density and backing pressure, it is found that the resulting number density for helium is ∼30% higher than for hydrogen at the same backing pressure. The observed differences in electron beam properties between the two gases can thus be explained by differences in plasma electron density. This interpretation is verified by repeating the laser wakefield acceleration experiment using similar plasma electron densities for the two gases, which then yielded electron beams with similar properties.

  20. Preliminary Overview of a Helium Cooling System for the Secondary Helium Loop in VHTR-based SI Hydrogen Production Facilities

    Shin, Youngjoon; Cho, Mintaek; Kim, Dahee; Lee, Taehoon; Lee, Kiyoung; Kim, Yongwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Nuclear hydrogen production facilities consist of a very high temperature gas-cooled nuclear reactor (VHTR) system, intermediate heat exchanger (IHX) system, and a sulfur-iodine (SI) thermochemical process. This study focuses on the coupling system between the IHX system and SI thermochemical process. To prevent the propagation of the thermal disturbance owing to the abnormal operation of the SI process components from the IHX system to the VHTR system, a helium cooling system for the secondary helium of the IHX is required. In this paper, the helium cooling system has been studied. The temperature fluctuation of the secondary helium owing to the abnormal operation of the SI process was then calculated based on the proposed coupling system model. Finally, the preliminary conceptual design of the helium cooling system with a steam generator and forced-draft air-cooled heat exchanger to mitigate the thermal disturbance has been carried out. A conceptual flow diagram of a helium cooling system between the IHX and SI thermochemical processes in VHTR-based SI hydrogen production facilities has been proposed. A helium cooling system for the secondary helium of the IHX in this flow diagram prevents the propagation of the thermal disturbance from the IHX system to the VHTR system, owing to the abnormal operation of the SI process components. As a result of a dynamic simulation to anticipate the fluctuations of the secondary helium temperature owing to the abnormal operation of the SI process components with a hydrogen production rate of 60 mol·H{sub 2}/s, it is recommended that the maximum helium cooling capacity to recover the normal operation temperature of 450 .deg. C is 31,933.4 kJ/s. To satisfy this helium cooling capacity, a U-type steam generator, which has a heat transfer area of 12 m{sup 2}, and a forced-draft air-cooled condenser, which has a heat transfer area of 12,388.67 m{sup 2}, are required for the secondary helium cooling system.

  1. Helium production in reactor materials

    Lippincott, E.P.; McElroy, W.N.; Farrar, H. IV.

    1975-02-01

    Comparisons of integral helium production measurements with predictions based on ENDF/B Version IV cross sections have been made. It is concluded that an ENDF/B helium production cross section file should be established in order to ensure a complete and consistent cross section evaluation to meet accuracies required for LMFBR, CTR, and LWR applications. (U.S.)

  2. Quantitative mass-spectrometric analysis of hydrogen helium isotope mixtures

    Langer, U.

    1998-12-01

    This work deals with the mass-spectrometric method for the quantitative analysis of hydrogen-helium-isotope mixtures, with special attention to fusion plasma diagnostics. The aim was to use the low-resolution mass spectrometry, a standard measuring method which is well established in science and industry. This task is solved by means of the vector mass spectrometry, where a mass spectrum is repeatedly measured, but with stepwise variation of the parameter settings of a quadruple mass spectrometer. In this way, interfering mass spectra can be decomposed and, moreover, it is possible to analyze underestimated mass spectra of complex hydrogen-helium-isotope mixtures. In this work experimental investigations are presented which show that there are different parameters which are suitable for the UMS-method. With an optimal choice of the parameter settings hydrogen-helium-isotope mixtures can be analyzed with an accuracy of 1-3 %. In practice, a low sensitivity for small helium concentration has to be noted. To cope with this task, a method for selective hydrogen pressure reduction has been developed. Experimental investigations and calculations show that small helium amounts (about 1 %) in a hydrogen atmosphere can be analyzed with an accuracy of 3 - 10 %. Finally, this work deals with the effects of the measuring and calibration error on the resulting error in spectrum decomposition. This aspect has been investigated both in general mass-spectrometric gas analysis and in the analysis of hydrogen-helium-mixtures by means of the vector mass spectrometry. (author)

  3. Helium production in mixed spectrum reactor-irradiated pure elements

    Kneff, D.W.; Oliver, B.M.; Skowronski, R.P.

    1986-01-01

    The objectives of this work are to apply helium accumulation neutron dosimetry to the measurement of neutron fluences and energy spectra in mixed-spectrum fission reactors utilized for fusion materials testing, and to measure helium generation rates of materials in these irradiation environments. Helium generation measurements have been made for several Fe, Cu Ti, Nb, Cr, and Pt samples irradiated in the mixed-spectrum High Flux Isotope Reactor (HFIR) and Oak Ridge Research Reactor (ORR) at the Oak Ridge National Laboratory. The results have been used to integrally test the ENDF/B-V Gas Production File, by comparing the measurements with helium generation predictions made by Argonne National Laboratory using ENDF/B-V cross sections and adjusted reactor spectra. The comparisons indicate consistency between the helium measurements and ENDF/B-V for iron, but cross section discrepancies exist for helium production by fast neutrons in Cu, Ti, Nb, and Cr (the latter for ORR). The Fe, Cu, and Ti work updates and extends previous measurements

  4. Validation of helium inlet design for ITER toroidal field coil

    Boyer, C.; Seo, K.; Hamada, K.; Foussat, A.; Le Rest, M.; Mitchell, N.; Decool, P.; Savary, F.; Sgobba, S.; Weiss, K.P.

    2014-01-01

    The ITER organization has performed design and its validation tests on a helium inlet structure for the ITER Toroidal Field (TF) coil under collaboration with CERN, KIT, and CEA Cadarache. Detailed structural analysis was performed in order to optimize the weld shape. A fatigue resistant design on the fillet weld between the shell covers and the jacket is an important point on the helium inlet structure. A weld filler material was selected based on tensile test at liquid helium temperature after Nb 3 Sn reaction heat treatment. To validate the design of the weld joint, fatigue tests at 7 K were performed using heat-treated butt weld samples. A pressure drop measurement of a helium inlet mock-up was performed by using nitrogen gas at room temperature in order to confirm uniform flow distribution and pressure drop characteristic. These tests have validated the helium inlet design. Based on the validation, Japanese and European Union domestic agencies, which have responsibilities of the TF coil procurement, are preparing the helium inlet mock-up for a qualification test. (authors)

  5. Interdiffusion of krypton and xenon in high-pressure helium

    Campana, R.J.; Jensen, D.D.; Epstein, B.D.; Hudson, R.G.; Baldwin, N.L.

    1980-01-01

    The interdiffusion of gaseous fission products in high-pressure helium is an important factor in the control of radioactivity in gas-cooled fast breeder reactors (GCFRs). As presently conceived, GCFRs use pressure-equalized and vented fuel in which fission gases released from the solid matrix oxide fuel are transported through the fuel rod interstices and internal fission product traps to the fuel assembly vents, where they are swept away to external traps and storage. Since the predominant transport process under steady-state operating conditions is interdiffusion of gaseous fission products in helium, the diffusion properties of krypton-helium and xenon-helium couples have been measured over the range of GCFR temperature and pressure conditions ( -1 ) and expected temperature dependence to the 1.66 power (Tsup(1.66)) at lower pressures and temperatures. Additional work is in progress to measure the behaviour of the krypton-helium and xenon-helium couples in GCFR fuel rod charcoal delay traps. (author)

  6. Helium-induced weld degradation of HT-9 steel

    Wang, Chin-An; Chin, B.A.; Lin, Hua T.; Grossbeck, M.L.

    1992-01-01

    Helium-bearing Sandvik HT-9 ferritic steel was tested for weldability to simulate the welding of structural components of a fusion reactor after irradiation. Helium was introduced into HT-9 steel to 0.3 and 1 atomic parts per million (appm) by tritium doping and decay. Autogenous single pass full penetration welds were produced using the gas tungsten arc (GTA) welding process under laterally constrained conditions. Macroscopic examination showed no sign of any weld defect in HT-9 steel containing 0.3 appm helium. However, intergranular micro cracks were observed in the HAZ of HT-9 steel containing 1 appm helium. The microcracking was attributed to helium bubble growth at grain boundaries under the influence of high stresses and temperatures that were present during welding. Mechanical test results showed that both yield strength (YS) and ultimate tensile strength (UTS) decreased with increasing temperature, while the total elongation increased with increasing temperature for all control and helium-bearing HT-9 steels

  7. Development of an Agent-based Model to Analyze Contemporary Helium Markets

    Riddle, Matthew E. [Argonne National Lab. (ANL), Argonne, IL (United States); Uckun, Canan [Argonne National Lab. (ANL), Argonne, IL (United States); Conzelmann, Guenter [Argonne National Lab. (ANL), Argonne, IL (United States); Macal, Charles M. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-02-01

    Although U.S. helium demand has remained relatively flat since 2009, exports of helium have increased significantly since then, driven primarily by demand for electronic and semiconductor manufacturing in Asia. In the midst of this global demand shift, the Helium Act dictates a new procedure for pricing and distributing the gas through a reserve that historically functioned as a loose “oligarchy.” The new procedure requires prices to be determined by the open market through auctions and a survey of market prices, as opposed to increasing prices according to the consumer price index. Response to these changes has caused temporary shortages, price increases, and a significant increase in the development of the helium extraction technologies used to produce helium from formerly marginal sources. Technologies are being developed and refined to extract helium from formerly low-yielding natural gas fields containing much lower amounts of helium than the previously considered economic threshold of 0.3%. Combining these transformative policies with the potential for new and significant global supplies from Qatar, Algeria, and Russia could lead to new and unforeseen market behaviors and reactions from global helium markets. The objective of the project is to analyze the global helium markets.

  8. Five second helium neutral beam injection using argon-frost cryopumping techniques

    Phillips, J.C.; Kellman, D.H.; Hong, R.; Kim, J.; Laughon, G.M.

    1995-01-01

    High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. The DIII-D neutral beam system has routinely provided up to 20 MW of deuterium neutral beam heating in support of experiments on the DIII-D tokamak. Operation of neutral beams with helium has historically presented a problem in that pulse lengths have been limited to 500 ms due to reliance solely on volume pumping of the helium gas. Helium is not condensed on the cryopanels. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection

  9. Helium-cooled nuclear reactor

    Longton, P.B.; Cowen, H.C.

    1975-01-01

    In helium cooled HTR's there is a by-pass circuit for cleaning purposes in addition to the main cooling circuit. This is to remove such impurities as hydrogen, methane, carbon monoxide and water from the coolant. In this system, part of the coolant successively flows first through an oxidation bed of copper oxide and an absorption bed of silica gel, then through activated charcoal or a molecular sieve. The hydrogen and carbon monoxide impurities are absorbed and the dry gas is returned to the main cooling circuit. To lower the hydrogen/water ratio without increasing the hydrogen fraction in the main cooling circuit, some of the hydrogen fraction converted into water is added to the cooling circuit. This is done, inter alia, by bypassing the water produced in the oxidation bed before it enters the absorption bed. The rest of the by-pass circuit, however, also includes an absorption bed with a molecular sieve. This absorbs the oxidized carbon monoxide fraction. In this way, such side effects as the formation of additional methane, carburization of the materials of the by-pass circuit or loss of graphite are avoided. (DG/RF) [de

  10. Five second helium neutral beam injection using argon-frost cryopumping techniques

    Phillips, J.C.; Kellman, D.H.; Hong, R.; Kim, J.; Laughon, G.M.

    1995-10-01

    High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection

  11. Helium behaviour in nuclear glasses

    Fares, T.

    2011-01-01

    The present thesis focuses on the study of helium behavior in R7T7 nuclear waste glass. Helium is generated by the minor actinides alpha decays incorporated in the glass matrix. Therefore, four types of materials were used in this work. These are non radioactive R7T7 glasses saturated with helium under pressure, glasses implanted with 3 He + ions, glasses doped with curium and glasses irradiated in nuclear reactor. The study of helium solubility in saturated R7T7 glass has shown that helium atoms are inserted in the glass free volume. The results yielded a solubility of about 10 16 at. cm -3 atm. -1 . The incorporation limit of helium in this type of glass has been determined; its value amounted to about 2*10 21 at. cm -3 , corresponding to 2.5 at.%. Diffusion studies have shown that the helium migration is controlled by the single population dissolved in the glass free volume. An ideal diffusion model was used to simulate the helium release data which allowed to determine diffusion coefficients obeying to the following Arrhenius law: D = D 0 exp(-E a /kBT), where D 0 = 2.2*10 -2 and 5.4*10 -3 cm 2 s -1 and E a = 0.61 eV for the helium saturated and the curium doped glass respectively. These results reflect a thermally activated diffusion mechanism which seems to be not influenced by the glass radiation damage and helium concentrations studied in the present work (up to 8*10 19 at. g -1 , corresponding to 0.1 at.%). Characterizations of the macroscopic, structural and microstructural properties of glasses irradiated in nuclear reactor did not reveal any impact associated with the presence of helium at high concentrations. The observed modifications i.e. a swelling of 0.7 %, a decrease in hardness by 38 %, an increase between 8 and 34 % of the fracture toughness and a stabilization of the glass structure under irradiation, were attributed to the glass nuclear damage induced by the irradiation in reactor. Characterizations by SEM and TEM of R7T7 glasses implanted

  12. A description of stress driven bubble growth of helium implanted tungsten

    Sharafat, Shahram; Takahashi, Akiyuki; Nagasawa, Koji; Ghoniem, Nasr

    2009-01-01

    Low energy (<100 keV) helium implantation of tungsten has been shown to result in the formation of unusual surface morphologies over a large temperature range (700-2100 deg. C). Simulation of these macroscopic phenomena requires a multiscale approach to modeling helium transport in both space and time. We present here a multiscale helium transport model by coupling spatially-resolved kinetic rate theory (KRT) with kinetic Monte Carlo (KMC) simulation to model helium bubble nucleation and growth. The KRT-based HEROS Code establishes defect concentrations as well as stable helium bubble nuclei as a function of implantation parameters and position from the implanted surface and the KMC-based Mc-HEROS Code models the growth of helium bubbles due to migration and coalescence. Temperature- and stress-gradients can act as driving forces, resulting in biased bubble migration. The Mc-HEROS Code was modified to simulate the impact of stress gradients on bubble migration and coalescence. In this work, we report on bubble growth and gas release of helium implanted tungsten W/O stress gradients. First, surface pore densities and size distributions are compared with available experimental results for stress-free helium implantation conditions. Next, the impact of stress gradients on helium bubble evolution is simulated. The influence of stress fields on bubble and surface pore evolution are compared with stress-free simulations. It is shown that near surface stress gradients accelerate helium bubbles towards the free surface, but do not increasing average bubble diameters significantly.

  13. State of the Art Report for a Bearing for VHTR Helium Circulator

    Lee, Jae Seon; Song, Kee Nam; Kim, Yong Wan; Lee, Won Jae

    2008-10-01

    A helium circulator in a VHTR(Very High Temperature gas-cooled Reactor) plays a core role which translates thermal energy at high temperature from a nuclear core to a steam generator. Helium as a operating coolant circulates a primary circuit in high temperature and high pressure state, and controls thermal output of a nuclear core by controlling flow rate. A helium circulator is the only rotating machinery in a VHTR, and its reliability should be guaranteed for reliable operation of a reactor and stable production of hydrogen. Generally a main helium circulator is installed on the top of a steam generator vessel, and helium is circulated only by a main helium circulator in a normal operation state. An auxiliary or shutdown circulator is installed at the bottom of a reactor vessel, and it is an auxiliary circulator for shutting down a reactor in case of refueling or accelerating cooling down in case of fast cooling. Since a rotating shaft of a helium circulator is supported by bearings, bearings are the important machine elements which determines reliability of a helium circulator and a nuclear reactor. Various types of support bearings have been developed and applied for circulator bearings since 1960s, and it is still developing for developing VHTRs. So it is necessary to review and analyze the current technical state of helium circulator support bearings to develop bearings for Koran developing VHTR helium circulator

  14. Towards helium-3 neutron polarizers

    Tasset, F.

    1995-01-01

    With a large absorption cross-section entirely due to antiparallel spin capture, polarized helium-3 is presently the most promising broad-band polarizer for thermal and epithermal neutrons. Immediate interest was raised amongst the neutron community when a dense gaseous 3 He polarizer was used for the first time in 1988, on a pulsed neutron beam at Los Alamos. With 20 W of laser power on a 30 cm long, 8.6 atm target, 40% 3 He polarization was achieved in a recent polarized electron scattering experiment at SLAC. In this technique the 3 He nuclei are polarized directly at an appropriate high pressure through spin-exchange collisions with a thick, optically pumped rubidium vapor. A different and competitive approach is being presently developed at Mainz University in collaboration with ENS Paris and now the ILL. A discharge is established in pure 3 He at low pressure producing excited metastable atoms which can be optically pumped with infra-red light. Highly effective exchange collision with the atoms remaining in the ground state quickly produces 75% polarization at 1.5 mbar. A truly non-magnetic system then compresses the polarized gas up to several bars as required. The most recent machine comprises a two-stage glass-titanium compressor. In less than 1 h it can inflate a 100 cm 3 target cell with three bars of polarized gas. The very long relaxation times (several days) now being obtained at high pressure with a special metallic coating on the glass walls, the polarized cell can be detached and inserted in the neutron beam as polarizer. We expect 50% 3 He-polarization to be reached soon, allowing such filters to compete favorably with existing Heusler-crystal polarizers at thermal and short neutron wavelengths. It must be stressed that such a system based on a 3 He polarization factory able to feed several passive, transportable, polarizers is well matched to neutron scattering needs. (orig.)

  15. Radiolytic reactions in the coolant of helium cooled reactors

    Tingey, G.L.; Morgan, W.C.

    1975-01-01

    The success of helium cooled reactors is dependent upon the ability to prevent significant reaction between the coolant and the other components in the reactor primary circuit. Since the thermal reaction of graphite with oxidizing gases is rapid at temperatures of interest, the thermal reactions are limited primarily by the concentration of impurity gases in the helium coolant. On the other hand, the rates of radiolytic reactions in helium are shown to be independent of reactive gas concentration until that concentration reaches a very low level. Calculated steady-state concentrations of reactive species in the reactor coolant and core burnoff rates are presented for current U. S. designed, helium cooled reactors. Since precise base data are not currently available for radiolytic rates of some reactions and thermal reaction rate data are often variable, the accuracy of the predicted gas composition is being compared with the actual gas compositions measured during startup tests of the Fort Saint Vrain high temperature gas-cooled reactor. The current status of these confirmatory tests is discussed. 12 references

  16. Accurate Determination of the Volume of an Irregular Helium Balloon

    Blumenthal, Jack; Bradvica, Rafaela; Karl, Katherine

    2013-01-01

    In a recent paper, Zable described an experiment with a near-spherical balloon filled with impure helium. Measuring the temperature and the pressure inside and outside the balloon, the lift of the balloon, and the mass of the balloon materials, he described how to use the ideal gas laws and Archimedes' principal to compute the average molecular…

  17. Study of equation-of-state of dense helium

    Cai Lingcang; Zhang Lin; Xiang Shikai; Jing Fuqian

    2001-01-01

    Hugoniot EOS, shock temperature of gas helium plasma (the initial pressure is 1.2 MPa and the initial temperature is 293 K) are measured with the help of shock compression technique and transient radiation pyrometer. The experimental Hugoniot data are good agreement with the theoretical prediction by Saha equation pus Debye-Huckel correction

  18. Transport of deuterium, tritium and helium in a tokamak

    Potters, J.H.H.M.

    1984-02-01

    A one-dimensional numerical model for determining steady-state radial profiles of the densities of the particles, including neutrals, in a multispecies toroidal plasma is described. For prescribed temperature profiles, the coupled momentum and particle balances of the ions are solved numerically with a newly developed compact finite difference scheme for a non-equidistant mesh. Neutral densities are obtained by solving the Boltzmann equations, using a collocation method. The model is applied to deuterium-tritium plasmas without and with a helium admixture. For the charged particles, Pfirsch-Schlueter transport, including the highly collisional extension, and either of two anomalous transport models are adopted. For equal densities of deuterons and tritons in the plasma centre, the neutral tritium density in front of the wall is found to be 1.3 to 1.6 times higher than that of deuterium, depending on the plasma density, the temperature profile and the transport model. Secondly, it is found that pumping neutral helium, originating from fusion alpha particles, out of a cold plasma/gas blanket surrounding the hot plasma is not feasible, as the helium gas density, corresponding to a relative abundance of alpha-particles in the plasma core below 10%, is very low. Although depending strongly on the ion transport model and being increased by elastic collisions between neutral helium and charged hydrogen isotopes, the neutral helium enrichment ratio is always much less than unity. (Auth.)

  19. Helium turbomachine design for GT-MHR power plant

    McDonald, C.F.; Orlando, R.J.

    1994-07-01

    The power conversion system in the gas turbine modular helium reactor (GT-MHR) power plant is based on a highly recuperated closed Brayton cycle. The major component in the direct cycle system is a helium closed-cycle gas turbine rated at 286 MW(e). The rotating group consists of an intercooled helium turbocompressor coupled to a synchronous generator. The vertical rotating assembly is installed in a steel vessel, together with the other major components (i.e., recuperator, precooler, intercooler, and connecting ducts and support structures). The rotor is supported on an active magnetic bearing system. The turbine operates directly on the reactor helium coolant, and with a temperature of 850 degree C (1562 degree F) the plant efficiency is over 47%. This paper addresses the design and development planning of the helium turbomachine, and emphasizes that with the utilization of proven technology, this second generation nuclear power plant could be in service in the first decade of the 21st century

  20. Imprints from the solar cycle on the helium atom and helium pickup ion distributions

    D. Rucinski

    Full Text Available Neutral interstellar helium atoms penetrate into the solar system almost unaffected by gas–plasma interactions in the heliospheric interface region, and thus can be considered as carriers of original information on the basic parameters (like density, temperature, bulk velocity of the Very Local Interstellar Medium (VLISM. Such information can nowadays be derived from analysis of data obtained from different experimental methods: in situ measurements of He atoms (Ulysses, observations of the solar backscattered He 584 A radiation (EUVE, in situ measurements of He + pickup ions (AMPTE, Ulysses, Wind, SOHO, ACE. In view of the current coordinated international ISSI campaign devoted to the study of the helium focusing cone structure and its evolution, we analyze expected variations of neutral He density, of He + pickup fluxes and of their phase space distributions at various phases of the solar activity cycle based on a realistic time-dependent modelling of the neutral helium and He + pickup ion distributions, which reflect solar cycle-induced variations of the photoionization rate. We show that the neutral helium density values are generally anticorrelated with the solar activity phase and in extreme cases (near the downwind axis the maximum-to-minimum density ratio may even exceed factors of ~ 3 at 1 AU. We also demonstrate that in the upwind hemisphere (at 1 AU and beyond the He + fluxes are correlated with the solar cycle activity, whereas on the downwind side the maximum of the expected flux up to distances of ~ 3 AU occurs around solar minimum epoch, and only further away does the correlation with solar activity become positive. Finally, we present the response of the phase space distribution spectra of He + pickup ions (in the solar wind frame for different epochs of the solar cycle and heliocentric distances from 1 to 5 AU covering the range of Ulysses, Wind and ACE observations.

    Key words. Solar physics, astrophysics and astronomy

  1. Imprints from the solar cycle on the helium atom and helium pickup ion distributions

    D. Rucinski

    2003-06-01

    Full Text Available Neutral interstellar helium atoms penetrate into the solar system almost unaffected by gas–plasma interactions in the heliospheric interface region, and thus can be considered as carriers of original information on the basic parameters (like density, temperature, bulk velocity of the Very Local Interstellar Medium (VLISM. Such information can nowadays be derived from analysis of data obtained from different experimental methods: in situ measurements of He atoms (Ulysses, observations of the solar backscattered He 584 A radiation (EUVE, in situ measurements of He + pickup ions (AMPTE, Ulysses, Wind, SOHO, ACE. In view of the current coordinated international ISSI campaign devoted to the study of the helium focusing cone structure and its evolution, we analyze expected variations of neutral He density, of He + pickup fluxes and of their phase space distributions at various phases of the solar activity cycle based on a realistic time-dependent modelling of the neutral helium and He + pickup ion distributions, which reflect solar cycle-induced variations of the photoionization rate. We show that the neutral helium density values are generally anticorrelated with the solar activity phase and in extreme cases (near the downwind axis the maximum-to-minimum density ratio may even exceed factors of ~ 3 at 1 AU. We also demonstrate that in the upwind hemisphere (at 1 AU and beyond the He + fluxes are correlated with the solar cycle activity, whereas on the downwind side the maximum of the expected flux up to distances of ~ 3 AU occurs around solar minimum epoch, and only further away does the correlation with solar activity become positive. Finally, we present the response of the phase space distribution spectra of He + pickup ions (in the solar wind frame for different epochs of the solar cycle and heliocentric distances from 1 to 5 AU covering the range of Ulysses, Wind and ACE observations.Key words. Solar physics, astrophysics and astronomy

  2. Exotic helium molecules

    Portier, M.

    2007-12-01

    We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range 4 He 2 (2 3 S 1 -2 3 P 0 ) molecule, or a 4 He 2 (2 3 S 1 -2 3 S 1 ) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 ± 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range 4 He 2 (2 3 S 1 -2 3 S 1 ) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime τ = (1.4 ± 0.3) μs is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

  3. Intelligent gas-mixture flow sensor

    Lammerink, Theodorus S.J.; Dijkstra, Fred; Houkes, Z.; van Kuijk, J.C.C.; van Kuijk, Joost

    A simple way to realize a gas-mixture flow sensor is presented. The sensor is capable of measuring two parameters from a gas flow. Both the flow rate and the helium content of a helium-nitrogen gas mixture are measured. The sensor exploits two measurement principles in combination with (local)

  4. Cryogenic tunable microwave cavity at 13GHz for hyperfine spectroscopy of antiprotonic helium

    Sakaguchi, J.; Gilg, H.; Hayano, R.S.; Ishikawa, T.; Suzuki, K.; Widmann, E.; Yamaguchi, H.; Caspers, F.; Eades, J.; Hori, M.; Barna, D.; Horvath, D.; Juhasz, B.; Torii, H.A.; Yamazaki, T.

    2004-01-01

    For the precise measurement of the hyperfine structure of antiprotonic helium, microwave radiation of 12.9GHz frequency is needed, tunable over +/-100MHz. A cylindrical microwave cavity is used whose front and rear faces are meshed to allow the antiprotons and laser beams to enter. The cavity is embedded in a cryogenic helium gas target. Frequency tuning of ∼300MHz with Q values of 2700-3000 was achieved using over-coupling and an external triple stub tuner. We also present Monte-Carlo simulations of the stopping distribution of antiprotons in the low-density helium gas using the GEANT4 package with modified energy loss routines

  5. Diffusion of Hydrogen and Helium in Inconel 625

    Palosz, W.; Gillies, D.; Lehoczky, S.

    2006-01-01

    Diffusion parameters for hydrogen and helium in Inconel 625 were investigated. The dependence of permeability of hydrogen in the temperature range 310 - 750 C is given. Solubility of hydrogen at 1 atm in the range 640 - 860 C was determined and diffusivity of the gas was calculated. Experiments with diffusion and solubility at 0.09 atm suggest a molecular mechanism of solution of hydrogen in the material. Diffusivity of helium was estimated at less than 10(exp -18) sq cm/s (at 1040 C).

  6. PG-100 helium loop in the MR reactor

    Ponomarev-Stepnoj, N.N.; Yakovlev, V.V.; Tikhonov, N.I.

    1983-01-01

    Main systems and production equipment units of PG-100 helium loop in the MR reactor are described. Possible long-term synchronizing operation of loop and reactor as well as possibility of carrying out life-time tests of spherical fuel elements and materials are shown. Serviceability of spherical fuel elements under conditions similar to the ones of HTGR-50 operation as well as high serviceability of cleanup system accepted for HTGR are verified. Due to low radiation dose the loop is operated without limits, helium losses in the loop don't exceed 0.5%/24 h, taking account of experimental gas sampling

  7. A compact quadrupole ion filter for helium detection

    Pereira, E.B.

    1981-01-01

    A compact quadrupole ion filter was conceived and constructed for optimum performance at the mass four region of the mass spectra. It was primarely designed for geological applications in the measurements of helium of soil-gases. The whole ion filter structure is 15 cm long by 3.5 cm diameter, including ion source and collecting plate. The sensitivity to helium is of the order of 10 - 2 A.torr - 1 measured at a total pressure of 6x10 - 6 torr and resolution 6. The system can be easily adapted to work as a dynamic residual gas analyser for other purposes. (Author) [pt

  8. Process for detecting leak faults using a helium mass spectrometer

    Divet, Claude; Morin, Claude.

    1977-01-01

    The description is given of a process for detecting very small leak faults putting into communication the outer and inner sides of the wall of a containment, one of these wall sides being in contact with gaseous helium under a pressure of around one torr, the other side being one of the limits of a space pumped down to a residual gas pressure under 10 -3 torr. This space is in communication with the measuring cell of a helium mass spectrometer. This process may be applied to the detection of faults in metal claddings of the fuel rods used in nuclear reactors [fr

  9. Helium effects on tritium storage materials

    Moysan, I.; Contreras, S.; Demoment, J.

    2008-01-01

    For ten years French Tritium laboratories have been using metal hydride storage beds with LaNi 4 Mn for process gas (HDT mixture) absorption, desorption and for both short and long term storage. This material has been chosen because of its low equilibrium pressure and of its ability to retain decay helium 3 in its lattice. Aging effects on the thermodynamic behavior of LaNi 4 Mn have been investigated. Aging, due to formation of helium 3 in the lattice, decreases the desorption isotherm plateau pressure and shifts the α phase to the higher stoichiometries. Life time of the two kinds of tritium (and isotopes) storage vessels managed in the laboratory depends on these aging changes. The Tritium Long Term Storage (namely STLT) and the hydride storage vessel (namely FSH 400) are based on LaNi 4 Mn even though they are not used for the same applications. STLT contains LaNi 4 Mn in an aluminum vessel and is designed for long term pure tritium storage. The FSH 400 is composed of LaNi 4 Mn included within a stainless steel container. This design is aimed at storing low tritium content mixtures (less than 3% of tritium) and for supplying processes with HDT gas. Life time of the STLT can reach 12 years. Life time of the FSH 400 varies from 1.2 years to more than 25 years depending on the application. (authors)

  10. Helium effects on tritium storage materials

    Moysan, I.; Contreras, S.; Demoment, J. [CEA Valduc, Service HDT, 21 - Is-sur-Tille (France)

    2008-07-15

    For ten years French Tritium laboratories have been using metal hydride storage beds with LaNi{sub 4}Mn for process gas (HDT mixture) absorption, desorption and for both short and long term storage. This material has been chosen because of its low equilibrium pressure and of its ability to retain decay helium 3 in its lattice. Aging effects on the thermodynamic behavior of LaNi{sub 4}Mn have been investigated. Aging, due to formation of helium 3 in the lattice, decreases the desorption isotherm plateau pressure and shifts the {alpha} phase to the higher stoichiometries. Life time of the two kinds of tritium (and isotopes) storage vessels managed in the laboratory depends on these aging changes. The Tritium Long Term Storage (namely STLT) and the hydride storage vessel (namely FSH 400) are based on LaNi{sub 4}Mn even though they are not used for the same applications. STLT contains LaNi{sub 4}Mn in an aluminum vessel and is designed for long term pure tritium storage. The FSH 400 is composed of LaNi{sub 4}Mn included within a stainless steel container. This design is aimed at storing low tritium content mixtures (less than 3% of tritium) and for supplying processes with HDT gas. Life time of the STLT can reach 12 years. Life time of the FSH 400 varies from 1.2 years to more than 25 years depending on the application. (authors)

  11. The Liquefaction of Hydrogen and Helium Using Small Coolers

    Green, Michael A.

    2006-01-01

    This report discusses the history of the liquefaction of hydrogen and helium using small coolers. This history dates form the 1960's when two stage GM coolers capable of reaching 7 K were used to liquefy helium and hydrogen by suing an added compressor and J-T circuit. Liquefaction using the added circuit failed to become mainstream because the J-T valve and heat exchanger clogged because of impurities in the gas being liquefied. Liquefaction using a GM cooler without an added J-T circuit proved to be difficult because the first stage was not used to pre-cool the gas coming to the second stage of the cooler. Once the gas being liquefied was pre-cooled using the cooler first stage, improvements in the liquefaction rates were noted. The advent of low temperature pulse tube cooler (down to 2.5 K) permitted one to achieve dramatic improvement is the liquefactions rates for helium. Similar but less dramatic improvements are expected for hydrogen as well. Using the PT-415 cooler, one can expect liquefaction rates of 15 to 20 liters per day for helium or hydrogen provided the heat leak into the cooler and the storage vessel is low. A hydrogen liquefier for MICE is presented at the end of this report

  12. Status of helium-cooled nuclear power systems. [Development potential

    Melese-d' Hospital, G.; Simnad, M

    1977-09-01

    Helium-cooled nuclear power systems offer a great potential for electricity generation when their long-term economic, environmental, conservation and energy self-sufficiency features are examined. The high-temperature gas-cooled reactor (HTGR) has the unique capability of providing high-temperature steam for electric power and process heat uses and/or high-temperature heat for endothermic chemical reactions. A variation of the standard steam cycle HTGR is one in which the helium coolant flows directly from the core to one or more closed cycle gas turbines. The effective use of nuclear fuel resources for electric power and nuclear process heat will be greatly enhanced by the gas-cooled fast breeder reactor (GCFR) currently being developed. A GCFR using thorium in the radial blanket could generate sufficient U-233 to supply the fuel for three HTGRs, or enough plutonium from a depleted uranium blanket to fuel a breeder economy expanding at about 10% per year. The feasibility of utilizing helium to cool a fusion reactor is also discussed. The status of helium-cooled nuclear energy systems is summarized as a basis for assessing their prospects. 50 references.

  13. Operating Manual of Helium Refrigerator (Rev. 2)

    Song, K.M.; Son, S.H.; Kim, K.S.; Lee, S.K.; Kim, M.S. [Korea Electric Power Research Institute, Taejon (Korea)

    2002-07-01

    A helium refrigerator was installed as a supplier of 20K cold helium to the cryogenic distillation system of WTRF pilot plant. The operating procedures of the helium refrigerator, helium compressor and auxiliary apparatus are described for the safety and efficient operation in this manual. The function of the helium refrigerator is to remove the impurities from the compressed helium of about 250psig, to cool down the helium from ambient temperature to 20K through the heat exchanger and expansion engine and to transfer the cold helium to the cryogenic distillation system. For the smoothly operation of helium refrigerator, the preparation, the start-up, the cool-down and the shut-down of the helium refrigerator are described in this operating manual. (author). 3 refs., 14 tabs.

  14. High Accuracy Vector Helium Magnetometer

    National Aeronautics and Space Administration — The proposed HAVHM instrument is a laser-pumped helium magnetometer with both triaxial vector and omnidirectional scalar measurement capabilities in a single...

  15. Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone

    Lowenstern, Jacob B.; Evans, William C.; Bergfeld, D.; Hunt, Andrew G.

    2014-01-01

    Helium is used as a critical tracer throughout the Earth sciences, where its relatively simple isotopic systematics is used to trace degassing from the mantle, to date groundwater and to time the rise of continents1. The hydrothermal system at Yellowstone National Park is famous for its high helium-3/helium-4 isotope ratio, commonly cited as evidence for a deep mantle source for the Yellowstone hotspot2. However, much of the helium emitted from this region is actually radiogenic helium-4 produced within the crust by α-decay of uranium and thorium. Here we show, by combining gas emission rates with chemistry and isotopic analyses, that crustal helium-4 emission rates from Yellowstone exceed (by orders of magnitude) any conceivable rate of generation within the crust. It seems that helium has accumulated for (at least) many hundreds of millions of years in Archaean (more than 2.5 billion years old) cratonic rocks beneath Yellowstone, only to be liberated over the past two million years by intense crustal metamorphism induced by the Yellowstone hotspot. Our results demonstrate the extremes in variability of crustal helium efflux on geologic timescales and imply crustal-scale open-system behaviour of helium in tectonically and magmatically active regions.

  16. Helium transport and exhaust studies in enhanced confinement regimes in DIII-D

    Wade, M.R.; Hillis, D.L.; Hogan, J.T.; Mahdavi, M.A.; Maingi, R.; West, W.P.; Burrell, K.H.; Finkenthal, D.F.; Gohil, P.; Groebner, R.J.

    1995-02-01

    A better understanding of helium transport in the plasma core and edge in enhanced confinement regimes is now emerging from recent experimental studies on DIII-D. Overall, the results are encouraging. Significant helium exhaust (τ* He /τ E ∼ 11) has been obtained in a diverted, ELMing H-mode plasma simultaneous with a central source of helium. Detailed analysis of the helium profile evolution indicates that the exhaust rate is limited by the exhaust efficiency of the pump (∼5%) and not by the intrinsic helium transport properties of the plasma. Perturbative helium transport studies using gas puffing have shown that D He /X eff ∼1 in all confinement regimes studied to date (including H-mode and VH-mode). Furthermore, there is no evidence of preferential accumulation of helium in any of these regimes. However, measurements in the core and pumping plenum show a significant dilution of helium as it flows from the plasma core to the pumping plenum. Such dilution could be the limiting factor in the overall removal rate of helium in a reactor system

  17. Irreversible adsorption of atmospheric helium on olivine: A lobster pot analogy

    Protin, Marie; Blard, Pierre-Henri; Marrocchi, Yves; Mathon, François

    2016-04-01

    This study reports new experimental results that demonstrate that large amounts of atmospheric helium may be adsorbed onto the surfaces of olivine grains. This behavior is surface-area-related in that this contamination preferentially affects grains that are smaller than 125 μm in size. One of the most striking results of our study is that in vacuo heating at 900 °C for 15 min is not sufficient to completely remove the atmospheric contamination. This suggests that the adsorption of helium may involve high-energy trapping of helium through irreversible anomalous adsorption. This trapping process of helium can thus be compared to a ;lobster pot; adsorption: atmospheric helium easily gets in, but hardly gets out. While this type of behavior has previously been reported for heavy noble gases (Ar, Kr, Xe), this is the first time that it has been observed for helium. Adsorption of helium has, until now, generally been considered to be negligible on silicate surfaces. Our findings have significant implications for helium and noble gas analysis of natural silicate samples, such as for cosmic-ray exposure dating or noble gas characterization of extraterrestrial material. Analytical procedures in future studies should be adapted in order to avoid this contamination. The results of this study also allow us to propose an alternative explanation for previously described matrix loss of cosmogenic 3He.

  18. Helium refrigerator-liquefier system for MHD generator

    Akiyama, Y.; Ishii, H.; Mori, Y.; Yamamoto, M.; Wada, R.; Ando, M.

    1974-01-01

    MHD power generators have been investigated in the Electro-Technical Laboratory as one of the National Research and Development Programmes. A helium refrigerator-liquefier system has been developed to cool the superconducting magnet for a 1000 kW class MHD power generator. The turboexpander with low temperature gas bearings and an alternator had been developed for the MHD project at the Electro-Technical Laboratory previously. The liquefaction capacity is 250 iota/h and the refrigeration power is 2.9 kW at 20 K. The superconducting magnet is 50 tons and the cryostat has a liquid helium volume of 2700 iota. The evaporation rate is 60 to 80 iota/h. It takes, in all 2 to 3 weeks to fill the cryostat with liquid helium. (author)

  19. Sealed liquid helium cryostats for mobile superconducting magnets

    Mulhall, B.E.; Rhodes, R.G.

    1976-01-01

    The predicted behaviour of the sealed cryostat system, which has been designed for the niobium-titanium superconducting coils of the on-board refrigerator of the small Wolfson electrodynamically levitated vehicle now under development, is summarized. Calculations suggest that the time taken by a sealed liquid helium cryostat to reach a specified final temperature is reasonably insensitive to the level of initial filling. Moreover, with a sufficiently large initial fill (for example, 70%) two or possibly three such temperature cycles, separated by the simple process of gas recovery, should be possible before replenishment of the helium is necessary. The useful time of operation of the cryostat between transfers of liquid helium is then not very much less than can be obtained with a freely boiling bath of liquid. For the low pressures involved the sealed cryostat is probably not much heavier or more complex than the open cryostat, and thus is ideal for a mobile application. (U.K.)

  20. Diffuse Helium Emission as a Precursory Sign of Volcanic Unrest

    Padron, E.; Perez, N.; Hernandez Perez, P. A.; Sumino, H.; Melian Rodriguez, G.; Barrancos, J.; Nolasco, D.; Padilla, G.; Dionis, S.; Rodriguez, F.; Hernandez, I.; Calvo, D.; Peraza, M.; Nagao, K.

    2012-12-01

    Since July 16, 2011, an anomalous seismicity at El Hierro island, the youngest and smallest of the Canary Islands, was recorded by IGN seismic network. After the occurrence of more than 10,000 seismic events, volcanic tremor was recorded since 05:15 of the October 10, by all of the seismic stations on the island, with highest amplitudes recorded in the southernmost station. During the afternoon of October 12 a large light-green coloured area was observed in the sea to the souht of La Restinga village (at the southernmost part of El Hierro island), suggesting the existence of a submarine eruption. Since October 12, frequent episodes of, turbulent gas emission and foaming, and the appearance of steamy lava fragments has been observed on the sea surface. As part of the volcanic surveillance of the island, the Instituto Volcanologico de Canarias (INVOLCAN) geochemical monitoring program is carrying out diffuse helium surveys on the surface environment of El Hierro (soil atmosphere). This nobel gas has been investigated because it has been considered an almost ideal geochemical indicator because it is chemically inert, physically stable, nonbiogenic, sparingly soluble in water under ambient conditions and almost non-adsorbable. At each survey, 600 sampling sites covering the whole island and following an homogeneous distribution are selected for helium measurements in the soil gases, The helium concentration gradients with respect to its value on air (5.24 ppm) allow us to estimate a pure diffusive emission rate of helium throughout the island. The first survey was carried out on the summer of 2003, when the island was on a quiescence period. At this survey, the amount of helium released by the volcanic system of El Hierro was estimated in 6 kg/d. Since the beginning of the seismic unrest, 13 helium emission surveys have been carried out. The helium emission rate has shown an excellent agreement with the evolution of the volcanic crisis of the island, reaching 30 kg

  1. Configuration and testing of a saturated vapor helium compressor

    Ludwigsen, J.L.; Iwasa, Y.; Smith, J.L.

    1986-01-01

    A saturated vapor helium compressor was designed and tested as a component of a helium-temperature refrigeration cycle. The use of the cold compressor allows reduction of both the precooling heat exchanger area and main compressor size compared to a conventional cycle due to increased pressure of the return gas. The compressor tested was a single-piston reciprocating device which was controlled with programmable hydraulic/pneumatic logic. The compressor was mounted at the cold end of a CTI Model 1400 helium liquefier. An average compression ratio of 2.4 was obtained and an average efficiency of 82% was achieved. In computing compressor efficiency, external heat leaks to the compressor were neglected

  2. The evolution of US helium-cooled blankets

    Wong, C.P.C.; Schultz, K.R.; Cheng, E.T.

    1991-01-01

    This paper reviews and compares four helium-cooled fusion reactor blanket designs. These designs represent generic configurations of using helium to cool fusion reactor blankets that were studied over the past 20 years in the United States of America (US). These configurations are the pressurized module design, the pressurized tube design, the solid particulate and gas mixture design, and the nested shell design. Among these four designs, the nested shell design, which was invented for the ARIES study, is the simplest in configuration and has the least number of critical issues. Both metallic and ceramic-composite structural materials can be used for this design. It is believed that the nested shell design can be the most suitable blanket configuration for helium-cooled fusion power and experimental reactors. (orig.)

  3. Helium refrigeration system for BNL colliding beam accelerator

    Brown, D.P.; Farah, Y.; Gibbs, R.J.; Schlafke, A.P.; Schneider, W.J.; Sondericker, J.H.; Wu, K.C.

    1983-01-01

    A Helium Refrigeration System which will supply the cooling required for the Colliding Beam Accelerator at Brookhaven National Laboratory is under construction. Testing of the compressor system is scheduled for late 1983 and will be followed by refrigerator acceptance tests in 1984. The refrigerator has a design capacity of 24.8 kW at a temperature level near 4K while simultaneously producing 55 kW for heat shield loads at 55K. When completed, the helium refrigerator will be the world's largest. Twenty-five oil-injected screw compressors with an installed total of 23,250 horsepower will supply the gas required. One of the unique features of the cycle is the application of three centrifugal compressors used at liquid helium temperature to produce the low temperatures (2.5K) and high flow rates (4154 g/s) required for this service

  4. Determination of polycyclic aromatic hydrocarbons in palm oil mill effluent by soxhlet extraction and gas chromatography-flame ionization detector

    Nor Fairolzukry Ahmad Rasdy; Mohd Marsin Sanagi; Wan Aini Wan Ibrahim; Ahmedy Abu Naim

    2008-01-01

    A method has been developed for the determination of polycyclic aromatic hydrocarbons (PAHs) from palm oil mill effluent based on gas chromatography-flame ionization detection. Extraction of spiked PAHs (napthalene, fluorene phenanthrene, fluoranthene and pyrene) in palm oil waste was carried out by Soxhlet extraction using hexane-dichloromethane (60:40 v/v) as the solvent. Excellent separations were achieved using temperature programmed GC on Ultra-1 fused-silica capillary column (30 m x 250 μm ID), carrier gas helium at a flow rate of 1 mL/ min. (author)

  5. Free-piston driver performance characterisation using experimental shock speeds through helium

    Gildfind, D. E.; James, C. M.; Morgan, R. G.

    2015-03-01

    Tuned free-piston driver operation involves configuring the driver to produce a relatively steady blast of driver gas over the critical time scales of the experiment. For the purposes of flow condition development and parametric studies, it is useful to establish some average working values of the driver pressure and temperature for a given driver operating condition. However, in practise, these averaged values need to produce sufficiently accurate estimates of performance. In this study, two tuned driver conditions in the X2 expansion tube have been used to generate shock waves through a helium test gas. The measured shock speeds have then been used to calculate the effective driver gas pressure and temperature after diaphragm rupture. Since the driver gas is typically helium, or a mixture of helium and argon, and the test gas is also helium, ideal gas assumptions can be made without significant loss of accuracy. The technique is applicable to tuned free-piston drivers with a simple area change, as well as those using orifice plates. It is shown that this technique can be quickly used to establish average working driver gas properties which produce very good estimates of actual driven shock speed, across a wide range of operating conditions. The use of orifice plates to control piston dynamics at high driver gas sound speeds is also discussed in the paper, and a simple technique for calculating the restriction required to modify an established safe condition for use with lighter gases, such as pure helium, is presented.

  6. Molecular dynamics and density functional simulations of tungsten nanostructure formation by helium plasma irradiation

    Ito, A.M.; Takayama, A.; Oda, Y.

    2014-10-01

    For the purposes of long-term use of tungsten diverter walls, it is necessary to suppress the surface deterioration due to the helium ash which induces the formations of helium bubbles and tungsten fuzzy nanostructures. In the present paper, the formation mechanisms of helium bubbles and tungsten fuzzy nanostructures were explained by the four-step process which is composed of the penetration process, the diffusion and agglomeration process, the helium bubble growth process and the tungsten fuzzy nanostructure formation process. The first to third step processes of the four-step process were investigated by using binary collision approximation, density functional theory and molecular dynamics, respectively. Furthermore, newly developed molecular dynamics and Monte-Carlo hybrid simulation has successfully reproduced the early formation process of tungsten fuzzy nanostructure. From these simulations, we here suggest the following key mechanisms of the formations of helium bubbles and tungsten fuzzy nanostructures: (1) By comparison between helium, neon, argon and hydrogen, the noble gas atoms can agglomerate limitlessly not only at a vacancy but also at an interstitial site. In particular, at the low incident energy, only helium atoms bring about the nucleation for helium bubble. (2) In the helium bubble growth process, the strain of the tungsten material around a helium atom is released as a dislocation loop, which is regarded as the loop punching phenomenon. (3) In the tungsten nanostructure formation process, the bursting of a helium bubble forms cavity and convexity in the surface. The helium bubbles tend to be grown and to burst at the cavity region, and then the difference of height between the cavity and convexity on the surface are enhanced. Consequently, the tungsten fuzzy nanostructure is formed. (author)

  7. Principles and characteristics of surface radon and helium techniques used in uranium exploration

    Pacer, J.C.; Czarnecki, R.F.

    1980-09-01

    Studies were carried out to determine the nature of some of the surface radon and helium techniques used for uranium exploration. By performing radon and helium measurements at three sites with differing geology and accessibility, we were able to examine the constraints on the features determined. The sites are the Red Desert in south central Wyoming, Copper Mountain in central Wyoming, and Spokane Mountain in eastern Washington. The radon techniques employed were: zinc sulfide detectors, an ionization chamber, alpha track detectors, thermoluminescence detectors, charcoal canisters, and the partial extraction of lead-210 from soil samples. Helium was measured in soil-gas samples, soil gas from collectors, and soil samples. The ratio helium-4/argon-36 was measured in soil gas

  8. Practical-scale tests of cryogenic molecular sieve for separating low-concentration hydrogen isotopes from helium

    Willms, R.S.; Taylor, D.J.; Enoeda, Mikio; Okuno, Kenji

    1994-01-01

    Earlier bench-scale work at the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory examined a number of adsorbents for their suitability for separating low-concentration hydrogen (no tritium) from helium. One of the effective adsorbents was Linde 5A molecular sieve. Recently, experiments including tritium were conducted using practical-scale adsorbers. These tests used existing cryogenic molecular sieve beds (CMSB's) which each contain about 1.6 kg of Linde 5A molecular sieve. They are part of the TSTA integrated tritium processing system. Gas was fed to each CMSB at about 13 SLPM with a nominal composition of 99% He, 0.98% H 2 and 0.02% HT. In all cases, for an extended period of time, the beds allowed no detectable (via Raman spectroscopy) hydrogen isotopes to escape in the bed effluent. Thereafter, the hydrogen isotopes appeared in the bed exit with a relatively sharp breakthrough curve. This work concludes that cryogenic molecular sieve adsorption is an practical and effective means of separating low-concentration hydrogen isotopes from a helium carrier

  9. Validation of Helium Inlet Design for ITER Toroidal Field Coil

    Boyer, C; Hamada, K; Foussat, A; Le Rest, M; Mitchell, N; Decool, P; Savary, F; Sgobba, S; Weiss, K-P

    2014-01-01

    The ITER organization has performed design and its validation tests on a helium inlet structure for the ITER Toroidal Field (TF) coil under collaboration with CERN, KIT, and CEA-Cadarache. Detailed structural analysis was performed in order to optimize the weld shape. A fatigue resistant design on the fillet weld between the shell covers and the jacket is an important point on the helium inlet structure. A weld filler material was selected based on tensile test at liquid helium temperature after Nb$_{3}$Sn reaction heat treatment. To validate the design of the weld joint, fatigue tests at 7 K were performed using heat-treated butt weld samples. A pressure drop measurement of a helium inlet mock-up was performed by using nitrogen gas at room temperature in order to confirm uniform flow distribution and pressure drop characteristic. These tests have validated the helium inlet design. Based on the validation, Japanese and European Union domestic agencies, which have responsibilities of the TF coil procurement, a...

  10. Helium-induced weld cracking in austenitic and martensitic steels

    Lin, H.T.; Chin, B.A.

    1991-01-01

    Helium was uniformly implanted into type 316 stainless steel and Sandvik HT-9 (12Cr-1MoVW) to levels of 0.18 to 256 and 0.3 to 1 a.p.p.m., respectively, using the ''tritium trick'' technique. Autogenous bead-on-plate, full penetration, welds were then produced under fully constrained conditions using the gas tungsten arc welding (GTAW) process. The control and hydrogen-charged plates of both alloys were sound and free of any weld defects. For the 316 stainless steel, catastrophic intergranular fracture occurred in the heat-affected zone (HAZ) of welds with helium levels ≥ 2.5 a.p.p.m. In addition to the HAZ cracking, brittle fracture along the centreline of the fusion zone was also observed for the welds containing greater than 100 a.p.p.m. He. For HT-9, intergranular cracking occurred in the HAZ along prior-austenite grain boundaries of welds containing 1 a.p.p.m. He. Electron microscopy observations showed that the cracking in the HAZ originated from the growth and coalescence of grain-boundary helium bubbles and that the fusion-zone cracking resulted from the growth of helium bubbles at dendrite boundaries. The bubble growth kinetics in the HAZ is dominated by stress-induced diffusion of vacancies into bubbles. Results of this study indicate that the use of conventional GTAW techniques to repair irradiation-degraded materials containing even small amounts of helium may be difficult. (author)

  11. Helium Leak Test for the PLS Storage Ring Chamber

    Choi, M. H.; Kim, H. J.; Choi, W. C.

    1993-01-01

    The storage ring vacuum system for the Pohang Light Source (PLS) has been designed to maintain the vacuum pressure of 10 1 0 Torr which requires UHV welding to have helium leak rate less than 1x10 1 0 Torr·L/sec. In order to develop new technique (PLS) welding technique), a prototype vacuum chamber has been welded by using Tungsten Inert Gas welding method and all the welded joints have been tested with a non-destructive method, so called helium leak detection, to investigate the vacuum tightness of the weld joints. The test was performed with a detection limit of 1x10 1 0 Torr·L/sec for helium and no detectable leaks were found for all the welded joints. Thus the performance of welding technique is proven to meet the criteria of helium leak rate required in the PLS Storage Ring. Both the principle and the procedure for the helium leak detection are also discussed

  12. Aircraft Carriers

    Nødskov, Kim; Kværnø, Ole

    as their purchases of aircraft carrier systems, makes it more than likely that the country is preparing such an acquisition. China has territorial disputes in the South China Sea over the Spratly Islands and is also worried about the security of its sea lines of communications, by which China transports the majority......, submarines, aircraft and helicopters, is not likely to be fully operational and war-capable until 2020, given the fact that China is starting from a clean sheet of paper. The United States of America (USA), the United Kingdom (UK), Russia and India are currently building or have made decisions to build new...

  13. Effects of particle size, helium gas pressure and microparticle dose on the plasma concentration of indomethacin after bombardment of indomethacin-loaded poly-L-lactic acid microspheres using a Helios gun system.

    Uchida, Masaki; Natsume, Hideshi; Kobayashi, Daisuke; Sugibayashi, Kenji; Morimoto, Yasunori

    2002-05-01

    We investigated the effects of the particle size of indomethacin-loaded poly-L-lactic acid microspheres (IDM-loaded PLA MS), the helium pressure used to accelerate the particles, and the bombardment dose of PLA MS on the plasma concentration of IDM after bombarding with IDM-loaded PLA MS of different particle size ranges, 20-38, 44-53 and 75-100 microm, the abdomen of hairless rats using the Helios gene gun system (Helios gun system). Using larger particles and a higher helium pressure, produced an increase in the plasma IDM concentration and the area under the plasma concentration-time curve (AUC) and resultant F (relative bioavailability with respect to intracutaneous injection) of IDM increased by an amount depending on the particle size and helium pressure. Although a reduction in the bombardment dose led to a decrease in C(max) and AUC, F increased on decreasing the bombardment dose. In addition, a more efficient F was obtained after bombarding with IDM-loaded PLA MS of 75-100 microm in diameter at each low dose in different sites of the abdomen compared with that after bolus bombardment with a high dose (dose equivalent). These results suggest that the bombardment injection of drug-loaded microspheres by the Helios gun system is a very useful tool for delivering a variety of drugs in powder form into the skin and systemic circulation.

  14. Gas

    1996-01-01

    The French government has decided to modify the conditions of extension of local natural gas authorities to neighbouring districts. The European Union is studying the conditions of internal gas market with the objective of more open markets although considering public service requirements

  15. Recent progress in the modelling of helium and tritium behaviour in irradiated beryllium pebbles

    Rabaglino, E.; Ronchi, C.; Cardella, A.

    2003-01-01

    One of the key issues of the European Helium Cooled Pebble Bed blanket is the behaviour under irradiation of beryllium pebbles, which have the function of neutron multiplier. An intense production of helium occurs in-pile, as well as a non negligible generation of tritium. Helium bubbles induce swelling and a high tritium inventory is a safety issue. Extensive studies for a better understanding, characterisation and modelling of the behaviour of helium and tritium in irradiated beryllium pebbles are being carried out, with the final aim to enable a reliable prediction of gas release and swelling in the full range of operating and accidental conditions of a Fusion Power Reactor. The general strategy consists in integrating studies on macroscopic phenomena (gas release) with the characterisation of corresponding microscopic diffusion phenomena (bubble kinetics) and the assessment of some fundamental diffusion parameter for the models (gas atomic diffusion coefficients). The present work gives a summary of the latest achievements in this context. By an inverse analysis of experimental out-of-pile gas release from weakly irradiated pebbles, coupled to the study of the characteristics of bubble population, it has been possible to assess the thermal diffusion coefficients of helium and tritium in and to improve and validate the classical model of gas precipitation into bubbles inside the grain. The improvement of the description of gas atomic diffusion and precipitation is the first step to enable a more reliable prediction of gas release

  16. Non-detection of a Helium Exosphere for the Hot Jupiter WASP-12b

    Kreidberg, Laura; Oklopčić, Antonija

    2018-06-01

    An exosphere was recently detected around the exoplanet WASP-107b, a low-density, warm Neptune, based on an absorption feature from metastable helium (which has a vacuum wavelength of 10833 \\AA). Inspired by the WASP-107b detection, we reanalyzed archival HST observations of another evaporating exoplanet, WASP-12b, to search for signs of helium in its exosphere. We find no significant increase in transit depth at 10833 \\AA. We compare this result to theoretical predictions from a 1D model, and find that the expected helium feature amplitude is small, in agreement with the observed non-detection. We discuss possible explanations for why the helium feature is weaker for WASP-12b than WASP-107b, and conclude that the amplitude of the signal is highly sensitive to the stellar spectrum and the geometry of the evaporating gas cloud. These considerations should be taken into account in the design of future searches for helium exospheres.

  17. Helium transport in TFTR

    Strachan, J.D.; Chan, A.

    1986-09-01

    Initial measurements of the 15 MeV protons produced in TFTR by the d( 3 He, p)α fusion reaction have been used to determine the time evolution of the central 3 He density. The signals following short 3 He gas puffs indicate inward transport times of about 100 msec

  18. CFD Analysis on the Passive Heat Removal by Helium and Air in the Canister of Spent Fuel Dry Storage System

    Shin, Do Young; Jeong, Ui Ju; Kim, Sung Joong [Hanyang University, Seoul (Korea, Republic of)

    2016-05-15

    In the current commercial design, the canister of the dry storage system is mainly backfilled with helium gas. Helium gas shows very conductive behavior due to high thermal conductivity and small density change with temperature. However, other gases such as air, argon, or nitrogen are expected to show effective convective behavior. Thus these are also considered as candidates for the backfill gas to provide effective coolability. In this study, to compare the dominant cooling mechanism and effectiveness of cooling between helium gas and air, a computational fluid dynamics (CFD) analysis for the canister of spent fuel dry storage system with backfill gas of helium and air is carried out. In this study, CFD simulations for the helium and air backfilled gas for dry storage system canister were carried out using ANSYS FLUENT code. For the comparison work, two backfilled fluids were modeled with same initial and boundary conditions. The observed major difference can be summarized as follows. - The simulation results showed the difference in dominant heat removal mechanism. Conduction for helium, and convection for air considering Reynolds number distribution. - The temperature gradient inside the fuel assembly showed that in case of air, more effective heat mixing occurred compared to helium.

  19. The 1/3-scale aerodynamics performance test of helium compressor for GTHTR300 turbo machine of JAERI (step 1)

    Takada, Shoji; Takizuka, Takakazu; Kunitomi, Kazuhiko; Xing, Yan

    2003-01-01

    A program for research and development on aerodynamics in a helium gas compressor was planned for the power conversion system of the Gas Turbine High Temperature Reactor (GTHTR300). The three-dimensional aerodynamic design of the compressor achieved a high polytropic efficiency of 90%, keeping a sufficient surge margin over 30%. To validate the design of the helium gas compressor of GTHTR300, aerodynamic performance tests were planned, and a 1/3-scale, 4-stage compressor model was designed. In the tests, the performance data of the helium gas compressor model will be acquired by using helium gas as a working fluid. The maximum design pressure at the model inlet is 0.88 MPa, which allows the Reynolds number to be sufficiently high. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

  20. Tritium and helium retention and release from irradiated beryllium

    Anderl, R.A.; Longhurst, G.R.; Oates, M.A.; Pawelko, R.J. [Idaho National Engineering and Environmental Lab., Idaho Falls, ID (United States)

    1998-01-01

    This paper reports the results of an experimental effort to anneal irradiated beryllium specimens and characterize them for steam-chemical reactivity experiments. Fully-dense, consolidated powder metallurgy Be cylinders, irradiated in the EBR-II to a fast neutron (>0.1 MeV) fluence of {approx}6 x 10{sup 22} n/cm{sup 2}, were annealed at temperatures from 450degC to 1200degC. The releases of tritium and helium were measured during the heat-up phase and during the high-temperature anneals. These experiments revealed that, at 600degC and below, there was insignificant gas release. Tritium release at 700degC exhibited a delayed increase in the release rate, while the specimen was at 700degC. For anneal temperatures of 800degC and higher, tritium and helium release was concurrent and the release behavior was characterized by gas-burst peaks. Essentially all of the tritium and helium was released at temperatures of 1000degC and higher, whereas about 1/10 of the tritium was released during the anneals at 700degC and 800degC. Measurements were made to determine the bulk density, porosity and specific surface area for each specimen before and after annealing. These measurements indicated that annealing caused the irradiated Be to swell, by as much as 14% at 700degC and 56% at 1200degC. Kr gas adsorption measurements for samples annealed at 1000degC and 1200degC determined specific surface areas between 0.04 m{sup 2}/g and 0.1 m{sup 2}/g for these annealed specimens. The tritium and helium gas release measurements and the specific surface area measurements indicated that annealing of irradiated Be caused a porosity network to evolve and become surface-connected to relieve internal gas pressure. (author)

  1. Blowing smoke rings in superfluid helium

    Allum, D.R.; McClintock, P.V.E.

    1977-01-01

    Among experiments designed to investigate the properties of superfluids, measurements are discussed which aim at determining the variation in the speed of an ion with the size of the electric field propelling it through liquid helium. The experimental set up using helium ions is described. The velocity-field characteristic shows an initial rise but at a higher electric field the ions exhibit the curious behaviour of slowing down before again increasing speed with force. The reason for this region of slowing down is here explained as being due to the fact that the charge is no longer carried by a free ion but, rather, by a charged vortex ring. As the ion speeds thorugh the liquid it suddenly creates a vortex ring and as one of the fundamental characteristics of a vortex ring is that its velocity is inversely proportional to its radius the speed reduction is explained. The subsequent rise in the characteristic indicates that the charge carriers are no longer straightforward charged vortex rings. This behaviour is attributed to ions 'falling off' their rings soon after creating them. It would appear that the force exerted by the electric field is so large that it overcomes the hydrodynamic force which binds the ion to the slowly moving vortex, enabling the ion to escape and accelerate away. In a final levelling off part of the characteristic curve it is considered that the ions are travelling faster than the critical velocity for roton creation, but are moving far below that for phonon creation. One may therefore conclude that the ion, as it travels through the liquid, transforms energy extracted from the electric field into rotons, which fan out forming a sort of wake behind it. (U.K.)

  2. Bed system performance in helium circulation mode

    Kim, Yean Jin; Jung, Kwang Jin; Ahn, Do Hee; Chung, Hong Suk [UST, Daejeon (Korea, Republic of); Kang, Hee Suk [KAERI, Daejeon (Korea, Republic of); Yun, Sei Hun [NFRI, Deajeon (Korea, Republic of)

    2016-05-15

    As a part of the International Thermonuclear Experimental Reactor (ITER) Project, We have conducted an experiment for storing hydrogen to depleted uranium and zirconium cobalt. The helium blanket effect has been observed in experiments using metal hydrides. The collapse of the hydrogen isotopes are accompanied by the decay heat and helium-3. Helium-3 dramatically reduces the hydrogen isotope storage capacity by surrounding the metal. This phenomenon is called a helium blanket effect. In addition the authors are working on the recovery and removal techniques of helium-3. In this paper, we discuss the equipment used to test the helium blanket effect and the results of a helium circulation experiment. The helium-3 produced surrounds the storage material surface and thus disturbs the reaction of the storage material and the hydrogen isotope. Even if the amount of helium-3 is small, the storage capacity of the SDS bed significantly drops. This phenomenon is the helium blanket effect. To resolve this phenomenon, a circulating loop was introduced. Using a circulating system, helium can be separated from the storage material. We made a helium loop that includes a ZrCo bed. Then using a metal bellows pump, we tested the helium circulation.

  3. A metastable helium trap for atomic collision physics

    Colla, M.; Gulley, R.; Uhlmann, L.; Hoogerland, M.D.; Baldwin, K.G.H.; Buckman, S.J.

    1999-01-01

    Full text: Metastable helium in the 2 3 S state is an important species for atom optics and atomic collision physics. Because of its large internal energy (20eV), long lifetime (∼8000s) and large collision cross section for a range of processes, metastable helium plays an important role in atmospheric physics, plasma discharges and gas laser physics. We have embarked on a program of studies on atom-atom and electron-atom collision processes involving cold metastable helium. We confine metastable helium atoms in a magneto-optic trap (MOT), which is loaded by a transversely collimated, slowed and 2-D focussed atomic beam. We employ diode laser tuned to the 1083 nm (2 3 S 1 - 2 3 P2 1 ) transition to generate laser cooling forces in both the loading beam and the trap. Approximately 10 million helium atoms are trapped at temperatures of ∼ 1mK. We use phase modulation spectroscopy to measure the trapped atomic density. The cold, trapped atoms can collide to produce either atomic He + or molecular He 2 + ions by Penning Ionisation (PI) or Associative Ionisation (AI). The rate of formation of these ions is dependant upon the detuning of the trapping laser from resonance. A further laser can be used to connect the 2 3 S 1 state to another higher lying excited state, and variation of the probe laser detuning used to measure interatomic collision potential. Electron-atom collision processes are studied using a monochromatic electron beam with a well defined spatial current distribution. The total trap loss due to electron collisions is measured as a function of electron energy. Results will be presented for these atomic collision physics measurements involving cold, trapped metastable helium atoms. Copyright (1999) Australian Optical Society

  4. Characterization of high flux magnetized helium plasma in SCU-PSI linear device

    Xiaochun, MA; Xiaogang, CAO; Lei, HAN; Zhiyan, ZHANG; Jianjun, WEI; Fujun, GOU

    2018-02-01

    A high-flux linear plasma device in Sichuan University plasma-surface interaction (SCU-PSI) based on a cascaded arc source has been established to simulate the interactions between helium and hydrogen plasma with the plasma-facing components in fusion reactors. In this paper, the helium plasma has been characterized by a double-pin Langmuir probe. The results show that the stable helium plasma beam with a diameter of 26 mm was constrained very well at a magnetic field strength of 0.3 T. The core density and ion flux of helium plasma have a strong dependence on the applied current, magnetic field strength and gas flow rate. It could reach an electron density of 1.2 × 1019 m-3 and helium ion flux of 3.2 × 1022 m-2 s-1, with a gas flow rate of 4 standard liter per minute, magnetic field strength of 0.2 T and input power of 11 kW. With the addition of -80 V applied to the target to increase the helium ion energy and the exposure time of 2 h, the flat top temperature reached about 530 °C. The different sizes of nanostructured fuzz on irradiated tungsten and molybdenum samples surfaces under the bombardment of helium ions were observed by scanning electron microscopy. These results measured in the SCU-PSI linear device provide a reference for International Thermonuclear Experimental Reactor related PSI research.

  5. Pierre Gorce working on a helium pump.

    1975-01-01

    This type of pump was designed by Mario Morpurgo, to circulate liquid helium in superconducting magnets wound with hollow conductors. M. Morpurgo, Design and construction of a pump for liquid helium, CRYIOGENICS, February 1977, p. 91

  6. Convective mixing in helium white dwarfs

    Vauclair, G.; Fontaine, G.

    1979-01-01

    The conditions under which convective mixing episodes take place between the helium envelopes and the underlying carbon layers in helium-rich white dwarfs are investigated. It is found that, for essentially any value of the initial helium content less than the maximum mass a helium convection zone can have, mixing does occur, and leads, in the vast majority of cases, to an almost pure carbon superficial composition. Mixing products that show only traces of carbon while retaining helium-dominated envelopes are possible only if the initial helium content is quite close to the maximum possible mass of the helium convection zone. In the presence of turbulence, this restriction could be relaxed, however, and the helium-rich lambda4670 stars may possibly be explained in this fashion

  7. The polarizability of diatomic helium. Ph.D. Thesis

    Fortune, P. J.

    1974-01-01

    The calculation of the electric dipole polarizability tensor of the He 2 dimer is described, and the results are used in the computation of several dielectric and optical properties of helium gas, at both high (322 K) and low (4 K) temperatures. The properties considered are the second dielectric virial coefficient, the second Kerr virial coefficient, and the depolarization ratio of the integrated intensities for the Raman scattering experiments. The thesis consists of five parts: the polarizability and various properties are defined; the calculation of the polarizability in the long-range region in terms of a quantum mechanical multipole expansion is described; the calculation of the He2 polarizability in the overlap region via coupled Hartree-Fock perturbation theory is described; the calculation of the quantum pair distribution function for both the He-3 and He-4 isotopes at 4 K is discussed; and the calculated values of the properties of helium gas are given.

  8. Chromatographic method of measurement of helium concentration in underground waters for dating in hydrological questions

    Najman, J.

    2008-04-01

    Research methods which use natural environmental indicators are widely applied in hydrology. Different concentrations of indicators and their isotopic components in ground waters allow to determine the genesis of waters and are valuable source of information about the water flow dynamics. One of the significant indicator is helium. The concentration of 4 He (helium) in ground water is a fine indicator in water dating in a range from a hundreds to millions of years (Aeschbach-Hertig i in., 1999; Andrews i in., 1989; Castro i in., 2000; Zuber i in., 2007). 4 He is also used for dating young waters of age about 10 years (Solomon i in., 1996). Thesis consist the description of elaborated in IFJ PAN in Krakow chromatographic measurement method of helium concentration in ground waters in aim of dating. Chapter 1 contain short introduction about ground water dating and chapter 2 description of helium property and chosen applications of helium for example in technology and earthquake predictions. Helium sources in ground waters are described in chapter 3. Helium concentration in water after infiltration (originated from atmosphere) to the ground water system depends mainly on the helium concentration coming from the equilibration with the atmosphere increased by additional concentration from '' excess air ''. With the increasing resistance time of ground water during the flow, radiogenic, non-atmospheric component of helium dissolves also in water. In chapter 4 two measurement methods of helium concentration in ground waters were introduced: mass spectrometric and gas chromatographic method. Detailed description of elaborated chromatographic measurement method of helium concentration in ground water contain chapter 5. To verify developed method the concentration of helium in ground waters from the regions of Krakow and Busko Zdroj were measured. For this waters the concentrations of helium are known from the earlier mass spectrometric measurements. The results of

  9. Summary report on technical experiences from high-temperature helium turbomachinery testing in Germany

    Weisbrodt, I.A.

    1996-01-01

    In Germany a comprehensive research and development program was initiated in 1968 for a Brayton (closed) cycle power conversion system. The program was for ultimate use with a high temperature, helium cooled nuclear reactor heat source (the HHT project) for electricity generation using helium as the working fluid. The program continued until 1982 in international cooperation with the United States and Switzerland. This document describes the designs and reports the results of testing activities that addressed the development of turbines, compressors, hot gas ducts, materials, heat exchangers and other equipment items for use with a helium working fluid at high temperatures. 67 refs, 34 figs, tabs

  10. Searching for Suicide Methods: Accessibility of Information About Helium as a Method of Suicide on the Internet.

    Gunnell, David; Derges, Jane; Chang, Shu-Sen; Biddle, Lucy

    2015-01-01

    Helium gas suicides have increased in England and Wales; easy-to-access descriptions of this method on the Internet may have contributed to this rise. To investigate the availability of information on using helium as a method of suicide and trends in searching about this method on the Internet. We analyzed trends in (a) Google searching (2004-2014) and (b) hits on a Wikipedia article describing helium as a method of suicide (2013-2014). We also investigated the extent to which helium was described as a method of suicide on web pages and discussion forums identified via Google. We found no evidence of rises in Internet searching about suicide using helium. News stories about helium suicides were associated with increased search activity. The Wikipedia article may have been temporarily altered to increase awareness of suicide using helium around the time of a celebrity suicide. Approximately one third of the links retrieved using Google searches for suicide methods mentioned helium. Information about helium as a suicide method is readily available on the Internet; the Wikipedia article describing its use was highly accessed following celebrity suicides. Availability of online information about this method may contribute to rises in helium suicides.

  11. The Modular Helium Reactor for Hydrogen Production

    E. Harvego; M. Richards; A. Shenoy; K. Schultz; L. Brown; M. Fukuie

    2006-01-01

    For electricity and hydrogen production, an advanced reactor technology receiving considerable international interest is a modular, passively-safe version of the high-temperature, gas-cooled reactor (HTGR), known in the U.S. as the Modular Helium Reactor (MHR), which operates at a power level of 600 MW(t). For hydrogen production, the concept is referred to as the H2-MHR. Two concepts that make direct use of the MHR high-temperature process heat are being investigated in order to improve the efficiency and economics of hydrogen production. The first concept involves coupling the MHR to the Sulfur-Iodine (SI) thermochemical water splitting process and is referred to as the SI-Based H2-MHR. The second concept involves coupling the MHR to high-temperature electrolysis (HTE) and is referred to as the HTE-Based H2-MHR

  12. Photoionization of helium dimers; Photoionisation von Heliumdimeren

    Havermeier, Tilo

    2010-06-09

    The helium dimer is one of the most weakly bound systems in the universe. This makes it an interesting quantum mechanical object for investigation. These Van der Waals Clusters can be produced in an expansion of a cryogenic gas jet through a small nozzle into vacuum. In the present experiment we examine the interaction of He dimers with synchrotron radiation at an energy range from 64 to 78 eV. We observed different pathways leading to single ionization of both He atoms of the dimer compound. This two close standing ions begin now to dissociate in cause of their coulomb potential. All charged fragments were detected in coincidence with a COLTRIMS system. Especially Interatomic Coulombic Decay (ICD) and the two step process (TS1) were clearly identified. Furthermore a distribution of the internuclear distance was obtained from the measured Kinetic Energy Release (KER). (orig.)

  13. Helium localization around the microscopic impurities embedded to liquid helium

    Gordon, E.B.; Shestakov, A.F.

    2000-01-01

    The structure and properties of the environment round the impurity atoms (Im) embedded in liquid helium are considered. It is shown that there are two qualitatively different types of structure of the He atom layer next to Im - attraction and repulsion structures. For the center attraction structure (strong Im-He interaction) the Im-He separation is longer than the equilibrium one for the pair Im-He potential, and the density and localization of He atoms are higher than in the bulk. It this case the He atom content in the layer, n, is almost independent of applied pressure. In the repulsion structure realized for alkaline metal atoms the Im-He separation is shorter than the equilibrium one and the density is lower than in the helium bulk. At T approx 1 K occupied are several states with different n and their energies differ only by approx 0.1 K, an increase in pressure resulting in a considerable reduction of n. The optical and EPR spectra of the atoms embedded to liquid and solid helium are interpreted on the basis of the analysis carried out. A simple model is proposed to evaluate the helium surroundings characteristics from the experimental pressure dependences of atomic line shifts in the absorption and emission spectra. The attraction structures in 3 He - 4 He mixtures are suggested to be highly enriched by 4 He atoms which the repulsion structures - by 3 He atoms. a possibility for existence of phase transitions in helium shells surrounding impurity atoms is considered

  14. Helium behaviour in aluminium under hydrostatic pressure

    Sokurskij, Yu.N.; Tebus, V.N.; Zudilin, V.A.; Tumanova, G.M.

    1989-01-01

    Effect of hydrostatic compression on equilibrium helium bubbles in low aluminium-lithium alloy irradiated in reactor at 570 K is investigated. Measurements of hydrostatic density and electron-microscopic investigations have shown, that application of up to 2 GPa pressure reduces equilibrium size of helium bubbles and reduces helium swelling. Kinetics and thermodynamics of the process are considered with application of 'rigid sphere' equation which describes helium state in bubbles

  15. Determination of occluded helium and oxygen in irradiated borosilicate glass samples

    Ramanjaneyulu, P.S.; Kulkarni, A.S.; Shrivastava, K.C.; Yadav, C.S.; Saxena, M.K.; Tomar, B.S.; Ramakumar, K.L.; Shah, J.G.

    2015-01-01

    Occluded gases in irradiated borosilicate glass were determined at 573, 873 and 1273 K for understanding the radiation damage in glass matrix. Hot vacuum extraction coupled with a quadrupole mass spectrometer technique was employed for the measurements. Relative sensitivity factors of various gases in QMS system were also determined and used for gas composition calculations. At 573 K only helium was found to get released whereas at 873 and 1273 K both helium and oxygen were released with major fraction of oxygen. (author)

  16. Structural bifurcation of microwave helium jet discharge at atmospheric pressure

    Takamura, Shuichi; Kitoh, Masakazu; Soga, Tadasuke

    2008-01-01

    Structural bifurcation of microwave-sustained jet discharge at atmospheric gas pressure was found to produce a stable helium plasma jet, which may open the possibility of a new type of high-flux test plasma beam for plasma-wall interactions in fusion devices. The fundamental discharge properties are presented including hysteresis characteristics, imaging of discharge emissive structure, and stable ignition parameter area. (author)

  17. Explosive helium burning in white dwarf stars

    Khokhlov, A.M. (AN SSSR, Moscow. Astronomicheskij Sovet)

    1984-04-01

    Helium burning kinetics in white dwarfs has been considered at constant temperatures T >= 10/sup 9/ K and densities rho >10/sup 5/ g/cm/sup 3/. It is found, that helium detonation in white dwarfs does not lead to formation of light (A < 56) elements. Thus, helium white dwarf model for supernova 1 is inconsistent with observations.

  18. Clustering of Helium Atoms at a ½

    Berg, F. v.d.; Heugten, W. v.; Caspers, L.M.; Veen, A. v.; Hosson, J.Th.M. de

    1977-01-01

    Atomistic calculations on a ½<111>{110} edge dislocation show a restricted tendency of clustering of helium atom along this dislocation. Clusters with up to 4 helium atoms have been studied. A cluster with 3 helium proved to be most stable.

  19. Muonium and neutral muonic helium

    Orth, H.

    1981-01-01

    In this brief article the current status on muonium spectroscopy with emphasis on recent developments will be summarized. The experimental and theoretical progress of the muonic helium atom will be reviewed. Future directions in this field of research will be discussed. (orig./HSI)

  20. Electric response in superfluid helium

    Chagovets, Tymofiy

    2016-01-01

    Roč. 488, May (2016), s. 62-66 ISSN 0921-4526 R&D Projects: GA ČR GP13-03806P Institutional support: RVO:68378271 Keywords : superfluid helium * electric response * second sound * ions in He II Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.386, year: 2016

  1. Production of negative helium ions

    Toledo, A.S. de; Sala, O.

    1977-01-01

    A negative helium ion source using potassium charge exchange vapor has been developed to be used as an injector for the Pelletron accelerator. 3 He and α beam currents of up to 2μA have been extracted with 75% particle transmission through the machine [pt

  2. Comparative studies of JENDL-3.3, JENDL-3.2, JEFF-3, JEF-2.2 and ENDF/B-6.8 data libraries on the Monte Carlo continuous energy modeling of the gas turbine-modular helium reactor operating with thorium fuels

    Talamo, Alberto; Gudowski, Waclaw

    2005-01-01

    One of the major benefits of the Gas Turbine-Modular Helium Reactor is the capability to operate with several different types of fuel; either Light Water Reactors waste, military plutonium or thorium represent valid candidates as possible types of fuel. In the present studies, we performed a comparison of various nuclear data libraries by the Monte Carlo Continuous Energy Burnup Code MCB applied to the Gas Turbine-Modular Helium Reactor operating on a thorium fuel. A thorium fuel offers valuable attractive advantages: low fuel cost, high reduction of actinides production and the possibility to enable the reactor to act as a breeder of fuel by the neutron capture of fertile 232 Th. We evaluated the possibility to mix thorium with small quantities, about 3% in atomic composition, of 239 Pu, 233 U and 235 U. The mass of thorium must be much larger than that one of plutonium or uranium because of the low capture cross section of thorium compared to the fission one of the fissile nuclides; at the same time, the quantity of the fissile isotopes must grant the criticality condition. These two simultaneous constraints force to load a huge mass of fuel in the reactor; consequently, we propose to allocate the fuel in TRISO particles with a large radius of the kernel. For each of the three different fuels we calculated the evolution of the fuel composition by the MCB code equipped with five different nuclear data libraries: JENDL-3.3, JENDL-3.2, JEFF-3, JEF-2.2 and ENDF/B. (author)

  3. Stationary Population Inversion in an Expanding Argon Plasma Jet by Helium Puffing

    Akatsuka, H; Kano, K

    2005-01-01

    ... out. Population inversion between Ar I excited states 5s'->4p'[1/2]1 and 5s'->4p[3/2]1,2, [5/2]2,3 is created by helium gas-contact cooling of electrons, whereas it is not created without gas-contact. Ar I lines 1.14 m, 1.34 m...

  4. Simplicity works for superfluid helium

    Bowley, Roger

    2000-01-01

    The famous philosopher Karl Popper once said that ''science is the art of systematic oversimplification''. Indeed, when faced with a new puzzle the trick is to simplify it without losing the essential physics - something that is easier said than done. However, this approach has paid off recently in low-temperature physics. Last year Richard Packard, Seamus Davis and co-workers at the University of California at Berkeley encountered a puzzling new phenomenon in superfluid helium-3, a quantum fluid that remains a liquid close to absolute zero and exhibits unusual properties such as the ability to flow without friction (A Machenkov et al. 1999 Phys. Rev. Lett. 83 3860). Previous experiments had revealed that certain effects in liquid helium are analogous to effects observed in superconductors, materials that lose all resistance to electric current at low temperatures. When the Berkeley researchers connected two reservoirs of superfluid helium-3, the superfluid flowed back and forth through apertures that formed a ''weak link'' between the two containers. This behaviour is similar to the oscillatory current of electrons that can flow across an insulating gap separating two superconductors - a device that is known as a Josephson junction. What was puzzling about the Berkeley results was that the helium-3 had two different stable configurations, both of which behaved in an unconventional way compared with a Josephson junction. This puzzle has now been solved independently by Sidney Yip at the National Center for Theoretical Sciences in Taiwan, and by Janne Viljas and Erkki Thuneberg at the Helsinki University of Technology in Finland (Phys. Rev. Lett. 1999 83 3864 and 3868). In this article the author describes the latest research on superfluid helium. (UK)

  5. Simplicity works for superfluid helium

    Bowley, Roger [University of Nottingham, Nottingham (United Kingdom)

    2000-02-01

    The famous philosopher Karl Popper once said that ''science is the art of systematic oversimplification''. Indeed, when faced with a new puzzle the trick is to simplify it without losing the essential physics - something that is easier said than done. However, this approach has paid off recently in low-temperature physics. Last year Richard Packard, Seamus Davis and co-workers at the University of California at Berkeley encountered a puzzling new phenomenon in superfluid helium-3, a quantum fluid that remains a liquid close to absolute zero and exhibits unusual properties such as the ability to flow without friction (A Machenkov et al. 1999 Phys. Rev. Lett. 83 3860). Previous experiments had revealed that certain effects in liquid helium are analogous to effects observed in superconductors, materials that lose all resistance to electric current at low temperatures. When the Berkeley researchers connected two reservoirs of superfluid helium-3, the superfluid flowed back and forth through apertures that formed a ''weak link'' between the two containers. This behaviour is similar to the oscillatory current of electrons that can flow across an insulating gap separating two superconductors - a device that is known as a Josephson junction. What was puzzling about the Berkeley results was that the helium-3 had two different stable configurations, both of which behaved in an unconventional way compared with a Josephson junction. This puzzle has now been solved independently by Sidney Yip at the National Center for Theoretical Sciences in Taiwan, and by Janne Viljas and Erkki Thuneberg at the Helsinki University of Technology in Finland (Phys. Rev. Lett. 1999 83 3864 and 3868). In this article the author describes the latest research on superfluid helium. (UK)

  6. Characterization of nano-bubbles as an oxygen carrier for in-situ bioremediation of organic pollutants in the subsurface

    KIM, E.; Jung, J.; Kang, S.; Choi, Y.

    2016-12-01

    In-situ bioremediation using bubbles as an oxygen carrier has shown its applicability for aerobic biodegradation of organic pollutants in the subsurface. By recent progresses, generation of nano-sized bubbles is possible, which have enhanced oxygen transfer efficiencies due to their high interfacial area and stability. We are developing an in-situ bioremediation technique using nano-bubbles as an oxygen carrier. In this study, nano-bubbles were characterized for their size and oxygen supply capacity. Nano-bubbles were generated with pure oxygen and pure helium gas. The stable nano-bubbles suspended in water were sonicated to induce the bubbles to coalesce, making them to rise and be released out of the water. By removing the bubbles, the water volume was decreased by 0.006%. The gas released from the bubble suspension was collected to measure the amount of gas in the nano-bubbles. For sparingly soluble helium gas 17.9 mL/L was released from the bubble suspension, while for oxygen 46.2 mL/L was collected. For the oxygen nano-bubble suspension, it is likely that the release of dissolved oxygen (DO) contributed to the collected gas volume. After removing the oxygen nano-bubbles, 36.0 mg/L of DO was still present in water. Altogether, the oxygen nano-bubble suspension was estimated to have 66.2 mg/L of oxygen in a dissolved form and 25.6 mg/L as nano-bubbles. A high DO level in the water was possible because of their large Laplace pressure difference across the fluid interface. Applying Young-Laplace equation and ideal gas law, the bubble diameter was estimated to be approximately 10 nm, having an internal pressure of 323 atm. Considering the saturation DO of 8.26 mg/L for water in equilibrium with the atmosphere, the total oxygen content of 91.8 mg/L in the nano-bubble suspension suggests its great potential as an oxygen carrier. Studies are underway to verify the enhanced aerobic biodegradation of organic pollutants in soils by injecting nano-bubble suspensions.

  7. Suicidal asphyxiation by using helium – two case reports

    Anna Smędra

    2015-05-01

    Full Text Available Helium is one of inert gases causing physical asphyxiation, whose excess content in the breathing atmosphere reduces the partial pressure of oxygen and may be fatal after short-term exposure. When breathing a mixture of an inert gas (helium, nitrogen, argon with a small amount of oxygen, with the possibility of exhaling carbon dioxide, no warning signs characteristic of suffocation are perceived by the subject. Freedom from discomfort and pain, effectiveness, rapid effect and relatively easy availability of required accessories have resulted in the use of inert gases for suicidal purposes. The paper reports two cases of suicide committed by using a special kit consisting of the so-called “suicide bag” (or “exit bag” filled with helium supplied through a plastic tube. In both cases, examination of the sites where the corpses were found and analysis of collected material allowed to establish that before their death the subjects had searched the Internet for instructions on how to commit suicide using helium. Due to the advanced putrefaction process, the autopsies failed to determine the causes of their death unequivocally. However, the circumstances surrounding the deaths suggested rapid asphyxiation as a result of oxygen deficiency in the breathing mixture. Since in cases of the type discussed here the cause of death cannot generally be established by autopsy, knowledge of the circumstances of disclosure of the corpse, as well as examination of the cadaver and the death scene is of utmost importance.

  8. Helium bubbles aggravated defects production in self-irradiated copper

    Wu, FengChao; Zhu, YinBo; Wu, Qiang; Li, XinZhu; Wang, Pei; Wu, HengAn

    2017-12-01

    Under the environment of high radiation, materials used in fission and fusion reactors will internally accumulate numerous lattice defects and bubbles. With extensive studies focused on bubble resolution under irradiation, the mutually effects between helium bubbles and displacement cascades in irradiated materials remain unaddressed. Therefore, the defects production and microstructure evolution under self-irradiation events in vicinity of helium bubbles are investigated by preforming large scale molecular dynamics simulations in single-crystal copper. When subjected to displacement cascades, distinguished bubble resolution categories dependent on bubble size are observed. With the existence of bubbles, radiation damage is aggravated with the increasing bubble size, represented as the promotion of point defects and dislocations. The atomic mechanisms of heterogeneous dislocation structures are attributed to different helium-vacancy cluster modes, transforming from the resolved gas trapped with vacancies to the biased absorption of vacancies by the over-pressured bubble. In both cases, helium impedes the recombination of point defects, leading to the accelerated formation of interstitial loops. The results and insight obtained here might contribute to understand the underlying mechanism of transmutant solute on the long-term evolution of irradiated materials.

  9. The Chalk River helium jet and skimmer system

    Schmeing, H.; Koslowsky, V.; Wightman, M.; Hardy, J.C.; MacDonald, J.A.; Faestermann, T.; Andrews, H.R.; Geiger, J.S.; Graham, R.L.

    1976-01-01

    A helium jet and skimmer system intended as an interface between a target location at the Chalk River tandem accelerator and the ion source of an on-line separator presently under construction has been developed. The system consists of a target chamber, a 125 cm long capillary, and a one stage skimmer chamber. The designs of the target and skimmer chambers allow one to vary a large number of independent flow and geometrical parameters with accurate reproducibility. Experiments with the β-delayed proton emitter 25 Si (tsub(1/2)=218 ms) produced in the reaction 24 Mg( 3 He,2n) 25 Si show that under optimized conditions about 75% of the reaction products leaving the target are transported to the skimmer. Of those, more than 90% pass through the skimmer orifice, which separates off 97.5% of the transport gas, helium. By introducing an additional helium flow across the skimming orifice the amount of helium separated off the transport jet can be increased to beyond 99.85%, leaving the high throughput of recoils unaffected. (Auth.)

  10. Apparatus to measure low level helium for neutron dosimetry

    Ozaki, Shuji; Takao, Yoshiyuki; Muramasu, Masatomo; Hida, Tomoya; Sou, Hirofumi; Nakashima, Hideki [Kyushu Univ., Fukuoka (Japan); Kanda, Yukinori

    1998-03-01

    An apparatus to measure low level helium in a solid sample for neutron dosimetry in the practical use such as area monitoring in the long-term and reactor surveillance was reported. In our previous work, the helium atoms measurement system (HAMS) was developed. A sample was evaporated in the furnace and the released gas from the sample was analyzed with the mass spectrometer of the system to determine the amount of helium contained in it. The system has been improved to advance the lower helium measurement limit in a solid sample for its application to an area monitoring system. The mass of a solid is up to 100mg. Two important points should be considered to advance the lower limit. One was to produce a high quality vacuum in the system chamber for suppressing background gases during the sample measurement. The other important point was to detect very small output from the mass spectrometer. A pulse counting system was used to get high sensitivity in the mass 4 analyzing. (author)

  11. A model for the operation of helium-filled proportional counter at low temperatures near 4.2 K

    Masaoka, Sei; Katano, Rintaro; Kishimoto, Shunji; Isozumi, Yasuhito

    2000-01-01

    In order to understand the operation of helium-filled proportional counter (HFPC) from the standpoint of fundamental atomic and molecular processes, we have surveyed previous works on collision processes in discharged helium gas. By analyzing gas gain curve, after-pulses and discharge current experimentally observed at 4.2 K, the electron avalanche and the secondary electron emission from cathode have been related to the collision processes in helium. A simplified model for the HFPC operation at low temperatures near 4.2 K has been constructed with the related processes

  12. HeREF-2003: Helium Refrigeration Techniques

    2003-01-01

    CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 Cost per participant: 500.- CHF Language: Bilingual English...

  13. HeREF-2003 : Helium Refrigeration Techniques

    2003-01-01

    CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. • Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 • Cost per participant: 500.- CHF ...

  14. Bio-SNG. Prospective renewable energy carrier in the E.ON gas grid; Bio-SNG. Zukuenftiger regenerativer Energietraeger im E.ON Gasnetz

    Adelt, Marius; Vogel, Alexander [E.ON Ruhrgas AG, Essen (Germany)

    2010-10-15

    Biogas processing and injection into the natural gas pipeline system on an industrial scale has been around in Germany for some time. E.ON operates a number of biogas plants with a production capacity of 200-1700 m{sup 3}/h. More plants are under construction or planned. The German government is looking to increase the share of biogas (upgraded to natural gas quality) in the pipeline system to 6 billion m{sup 3}/a by 2020, so significantly more production capacity is needed. Biogas is produced mainly from dedicated energy crops (maize) as well as several catch crops and, depending on the processing plant, various amounts of bio residues. The biogas is upgraded to natural gas quality and fed into the pipeline system as biomethane (E.ON: bio natural gas). To achieve the ambitious production targets it will be necessary to tap the unused potential of wood for gasification and subsequent methanisation into bio-SNG. E.ON AG actively promotes the development and introduction of this technology. This article provides an overview of different aspects of bio-SNG production and use including: Utilisation paths for biomethane/bio-SNG (heat, fuel, CHP), Potential of wood for bio-SNG production, Bio-SNG production technologies, Current E.ON activities and projects. (orig.)

  15. Antibacterial resistance in Streptococcus pyogenes (GAS) from healthy carriers and tonsillitis patients and association with antibacterial sale in the Faroe Islands

    Magnussen, Marita D; Gaini, Shahin; Gislason, Hannes

    2016-01-01

    The aim of this study was to investigate the antibacterial resistance of Streptococcus pyogenes (GAS), and correlate the findings with the sales of erythromycin and tetracycline. General practitioners in the Faroe Islands were recruited to send oropharyngeal swabs. From an ongoing pneumococcal...

  16. Chromatographic efficiency of polar capillary columns applied for the analysis of fatty acid methyl esters by gas chromatography.

    Waktola, Habtewold D; Mjøs, Svein A

    2018-04-01

    The chromatographic efficiency that could be achieved in temperature-programmed gas chromatography was compared for four capillary columns that are typically applied for analysis of fatty acid methyl esters (FAME). Three different carrier gases, hydrogen, helium and nitrogen, were applied. For each experiment, the carrier gas velocities and the temperature rates were varied with a full 9 × 3 design, with nine levels on the carrier gas velocity and temperature rates of 1, 2 or 3°C/min. Response surface methodology was used to create models of chromatographic efficiency as a function of temperature rate and carrier gas velocity. The chromatographic efficiency was defined as the inverse of peak widths measured in retention index units. The final results were standardized so that the efficiencies that could be achieved within a certain time frame, defined by the retention time of the last compound in the chromatogram, could be compared. The results show that there were clear differences in the efficiencies that could be achieved with the different columns and that the efficiency decreased with increasing polarity of the stationary phase. The differences can be explained by higher resistance to mass transfer in the stationary phase in the most polar columns. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Method for optical 15N analysis of small amounts of nitrogen gas released from an automatic nitrogen analyzer

    Arima, Yasuhiro

    1981-01-01

    A method of optical 15 N analysis is proposed for application to small amounts of nitrogen gas released from an automatic nitrogen analyzer (model ANA-1300, Carlo Erba, Milano) subjected to certain set modifications. The ANA-1300 was combined with a vacuum line attached by a molecular sieve 13X column. The nitrogen gas released from the ANA-1300 was introduced with a carrier gas of helium into the molecular sieve column which was pre-evacuated at 10 -4 Torr and cooled with outer liquid nitrogen. After removal of the helium by evacuation, the nitrogen gas fixed on the molecular sieve was released by warming the column, and then, it was sealed into pre-evacuated pyrex glass tubes at 4.5 - 5.0 Torr. In the preparation of discharge tubes, contamination of unlabelled nitrogen occurred from the carrier gas of standard grade helium, and the relative lowering of the 15 N value by it was estimated to be less than 1% when over 700 μg nitrogen was charged on the ANA-1300; when 200 μg nitrogen was charged, it was about 3.5%. However, the effect of the contamination could be corrected for by knowing the amount of contaminant nitrogen. In the analysis of plant materials by the proposed method, the coefficient of variation was less than 2%, and no significant difference was observed between results given by the present method and by the ordinary method in which samples were directly pyrolyzed in the discharge tubes by the Dumas method. The present method revealed about 1.5 μg of cross-contaminated nitrogen and was applicable to more than 200 μg of sample nitrogen. (author)

  18. A preliminary investigation of the diffusion of helium in zirconium

    Reed, D.J.; Faulkner, D.

    1976-10-01

    The out-diffusion of helium, introduced into polycrystalline zirconium at room temperature by ion-implantation at 100 keV to a peak concentration of 1ppm, was found to occur in two principal regions. Two evolution rate maxima, obtained during post-implantation target annealing at 2.6 0 K s -1 , were observed in close proximity at 330 0 C (0.28 Tsub(m)) and 450 0 C (0.34 Tsub(m)) comprising the principal stage, with a subordinate stage occurring at 600 0 C (0.4 Tsub(m)). These data were compared with similar maxima observed in nickel at 600 0 C (0.5 Tsub(m)) and 850 0 C (0.65 Tsub(m)). The results imply a high helium diffusivity over the 0.5 mm experimental range in comparison with nickel, and an exceptionally high diffusivity taking into account the melting temperature of zirconium. On the basis of a diffusion model proposed earlier for nickel, activation energies of 1.37 and 1.66 eV have been assigned to the principal maxima at 330 0 C and 450 0 C, and a value of 2.41 eV to the maximum at 600 0 C. The long range diffusivity of helium manifested by its thermal evolution from uniformly filled 120 mm thick foils was found to be much lower than that measured for short range migration. An empirical activation energy of approximately 3 eV was estimated for this process, thought to be a result of bubble migration. The release of helium from zirconium has been explained by comparison with nickel data. The proposed substitutional de-trapping mechanism has been invoked to account for the principal evolution rate maxima at 330 0 C. Helium release observed at 600 0 C has been explained by the annealing of radiation damage, so allowing gas trapped therein to be evolved. (author)

  19. Impulse approximation in solid helium

    Glyde, H.R.

    1985-01-01

    The incoherent dynamic form factor S/sub i/(Q, ω) is evaluated in solid helium for comparison with the impulse approximation (IA). The purpose is to determine the Q values for which the IA is valid for systems such a helium where the atoms interact via a potential having a steeply repulsive but not infinite hard core. For 3 He, S/sub i/(Q, ω) is evaluated from first principles, beginning with the pair potential. The density of states g(ω) is evaluated using the self-consistent phonon theory and S/sub i/(Q,ω) is expressed in terms of g(ω). For solid 4 He resonable models of g(ω) using observed input parameters are used to evaluate S/sub i/(Q,ω). In both cases S/sub i/(Q, ω) is found to approach the impulse approximation S/sub IA/(Q, ω) closely for wave vector transfers Q> or approx. =20 A -1 . The difference between S/sub i/ and S/sub IA/, which is due to final state interactions of the scattering atom with the remainder of the atoms in the solid, is also predominantly antisymmetric in (ω-ω/sub R/), where ω/sub R/ is the recoil frequency. This suggests that the symmetrization procedure proposed by Sears to eliminate final state contributions should work well in solid helium

  20. Liquid helium plant in Dubna

    Agapov, N.N.; Baldin, A.M.; Kovalenko, A.D.

    1995-01-01

    The liquid-helium cooling capacity installed at the Laboratory of High Energies is about 5 kw at a 4.5 K temperature level. It is provided with four industrial helium liquefiers of 1.6 kw/4.5 K each. They have been made by the Russian enterprise NPO GELYMASH and upgraded by the specialists of the Laboratory. The first one was put into operation in 1980, the two others in 1991, and the last one is under commissioning. The development of the LHE cryoplant was concerned with the construction of the new superconducting accelerator Nuclotron aimed to accelerate nuclei and heavy ions up to energies of 6 GeV/u. The first test run at the Nuclotron was carried out in March 1993, and the total running time has been about 2000 hours up to now. Since 1992 the cryoplant has been intensively used by the users outside the Laboratory. More than a million liters of liquid helium was provided in 1993 for such users. The reliability of the cryoplant system was as high as 98 percent for 4500 hours of operation in 1993-1994. 7 refs., 4 figs., 1 tab

  1. Tribological behavior of zirconium coatings in high temperature helium

    Cachon, Lionel; Albaladejo, Serge; Taraud, Pascal

    2005-01-01

    In France, a comprehensive research and development program is leaded by the CEA, since 2001, for the Gas Cooled Reactor (GCR) project using helium as cooling fluid, in order to establish the feasibility of the technology of an early VHTR prototype to be started by 2015, and then to qualify the generic VHTR technology, so as to meet similar objectives for the GFR. In this frame a tribology program has been launched. The purpose of the work presented in this paper is to describe the CEA Helium tribology study: high temperature gas cooled reactors require wear protection (thermal barriers, control rod drive mechanisms, reactor internals, ...). Tests in helium atmosphere are necessary to be fully representative of tribological environments and finally to check the possible materials or coatings which can provide a reliable answer to these situations. The main characteristics and first experimental results are thus described. This paper focus on tribology tests leaded in the temperature range 800-1000degC, on ceramic (ZrO 2 -Y 2 O 3 ) with and without solid lubricant like CaF2). (author)

  2. Self-trapping of helium in metals

    Wilson, W.D.; Bisson, C.L.; Baskes, M.I.

    1981-01-01

    Atomistic calculations are presented which demonstrate that helium atoms in a metal lattice are able to cluster with each other, producing vacancies and nearby self-interstitial defects. Even a small number of helium atoms is found to be sufficient to create these large distortions. As few as five interstitial helium can spontaneously produce a lattice vacancy and nearby self-interstitial. An eight-helium-atom cluster gives rise to two such defects, and 16 helium atoms to more than five self-interstitial vacancy pairs. It was noted that the self-interstitials prefer to agglomerate on the same ''side'' of the helium cluster rather than to spread themselves out uniformly. The binding energy of each additional helium atom to these clusters increases with helium concentration and the trap is apparently unsaturable. A rate theory using these atomistic binding energies has been used to calculate the kinetics of helium-bubble nucleation and growth. The results are consistent with measurements of the properties of helium resulting from tritium decay

  3. Helium in inert matrix dispersion fuels

    Veen, A. van; Konings, R.J.M.; Fedorov, A.V.

    2003-01-01

    The behaviour of helium, an important decay product in the transmutation chains of actinides, in dispersion-type inert matrix fuels is discussed. A phenomenological description of its accumulation and release in CERCER and CERMET fuel is given. A summary of recent He-implantation studies with inert matrix metal oxides (ZrO 2 , MgAl 2 O 4 , MgO and Al 2 O 3 ) is presented. A general picture is that for high helium concentrations helium and vacancy defects form helium clusters which convert into over-pressurized bubbles. At elevated temperature helium is released from the bubbles. On some occasions thermal stable nano-cavities or nano-pores remain. On the basis of these results the consequences for helium induced swelling and helium storage in oxide matrices kept at 800-1000 deg. C will be discussed. In addition, results of He-implantation studies for metal matrices (W, Mo, Nb and V alloys) will be presented. Introduction of helium in metals at elevated temperatures leads to clustering of helium to bubbles. When operational temperatures are higher than 0.5 melting temperature, swelling and helium embrittlement might occur

  4. An interbubble fracture mechanism of blister formation on helium-irradiated metals

    Evans, J.H.

    1977-01-01

    This paper describes a new model of surface blister formation in which a blister is nucleated by the interbubble fracture of highly overpressurized helium bubbles. As in other gas-driven models, the internal release of helium then provides the driving force for blister lid deformation. The high pressures required for the suggested mode of fracture are a result of the difficulty, experienced by the bubbles in acquiring vacancies. By considering the bubble growth mechanisms, the critical conditions for interbubble fracture are shown to depend on the helium dose and energy, the bubble size, and their depth in the irradiated material. These parameters and other aspects of blister formation are discussed on the basis of the proposed model. One important result concerns the position of the fracture plane; because of the usual displacement of damage and helium peaks relative to depth, this plane can lie well beyond the helium peak. Thus, the disagreement inherent in previous gas models between helium range and measured blister lid thickness values can be resolved without recourse to lateral stress arguments. (Auth.)

  5. Cryopumping of deuterium hydrogen and helium mixtures on smooth 4.2 K surfaces

    Chou, T.S.; Halama, H.J.

    1977-01-01

    The large quantities of deuterium and hydrogen to be pumped in a fusion reactor and its subsystems favor cryopumping over other pumping methods. Cryogen consumption and the operating pressure will not only depend on the gas to be pumped, but also on the amount of helium gas present in the system. In fact, residual helium pressure between pulses will determine the power dissipation of the pump, and hence, influence the choice of cryocondensation or cryosorption. In this paper we will present the results of our studies on (1) cryotrapping of helium in thick D 2 and H 2 films and hydrogen in D 2 films at 4.2 K; (2) diffusion of He and H 2 from D 2 films; (3) steady-state liquid helium consumption; (4) liquid helium consumption as a function of D 2 and H 2 fluxes being pumped; (5) liquid helium consumption as a function of He partial pressure in the system. Finally, these measurements will suggest maximum permissible He to D 2 and He to H 2 ratios in a cryocondensation pump

  6. Applicability of the dielectric barrier discharge for helium ash measurements in the divertor region

    Książek Ireneusz

    2016-06-01

    Full Text Available Controlled fusion based on the magnetic confinement of the plasma is one of the main aims of the Euro-fusion programme. In the fusion device, the hydrogen isotopes, in nuclear reactions, will produce helium nuclei. The products, as the ash, will be removed from the plasma in the region of the so-called divertor. Controlling the helium to hydrogen ratio in this ‘exhaust gas’ will provide information about the efficiency of the fusion process as well as of the efficiency of the helium removal system. One of the methods to perform this task is to study the properties of the discharge conducted in such exhaust gas. In this paper, the applicability of the dielectric barrier discharge (DBD is studied. This preliminary experiment shows a great potential in applicability of this kind of discharge. The optical as well as pulse-height spectra were studied, both revealing very promising properties. In the optical spectrum, one can observe well separated hydrogen and helium spectral lines, with intensities of the same order of magnitude. Moreover, in the registered spectral region, the molecular spectra are negligible. The pulse-height spectra reveal very distinct shape in helium and hydrogen. Checking of this spectrum could provide parallel (redundant information about the partial pressure of helium in the magnetic confinement fusion (MCF device exhaust gas.

  7. Leak detection on the DIII-D tokamak using helium entrainment techniques

    Brooks, N.H.; Baxi, C.; Anderson, P.

    1988-01-01

    The entrainment of helium in a viscous gas flow was utilized to compartmentalize, and then to pinpoint, a leak across the inner skin of the double-walled DIII-D vacuum vessel. Inaccessible from the outside, the leak connected the cooling channels in the wall interspace with the primary vacuum chamber. By entraining helium in the pressurized flow from the single-pass gas circulation system, well-defined portions of the wall were exposed to helium without disassembly of the poorly accessible cooling manifolds. Varying the helium injection point permitted the localization of the leak to a single 30 0 toroidal sector of the vessel. The exact location of the leak was found from inside the vessel by spraying helium on suspect regions, while sweeping the contents of the cooling channels to the foreline of a Varian Contraflow leak detector with a 0.1 Pa m 3 /s flow of nitrogen. Flow speed calculations were used to predict the response time to entrained helium of the actual leak detection setup

  8. Measurements of the purge helium pressure drop across pebble beds packed with lithium orthosilicate and glass pebbles

    Abou-Sena, Ali, E-mail: ali.abou-sena@kit.edu; Arbeiter, Frederik; Boccaccini, Lorenzo V.; Schlindwein, Georg

    2014-10-15

    Highlights: • The objective is to measure the purge helium pressure drop across various HCPB-relevant pebble beds packed with lithium orthosilicate and glass pebbles. • The purge helium pressure drop significantly increases with decreasing the pebbles diameter from one run to another. • At the same superficial velocity, the pressure drop is directly proportional to the helium inlet pressure. • The Ergun's equation can successfully model the purge helium pressure drop for the HCPB-relevant pebble beds. • The measured values of the purge helium pressure drop for the lithium orthosilicate pebble bed will support the design of the purge gas system for the HCPB breeder units. - Abstract: The lithium orthosilicate pebble beds of the Helium Cooled Pebble Bed (HCPB) blanket are purged by helium to transport the produced tritium to the tritium extraction system. The pressure drop of the purge helium has a direct impact on the required pumping power and is a limiting factor for the purge mass flow. Therefore, the objective of this study is to measure the helium pressure drop across various HCPB-relevant pebble beds packed with lithium orthosilicate and glass pebbles. The pebble bed was formed by packing the pebbles into a stainless steel cylinder (ID = 30 mm and L = 120 mm); then it was integrated into a gas loop that has four variable-speed side-channel compressors to regulate the helium mass flow. The static pressure was measured at two locations (100 mm apart) along the pebble bed and at inlet and outlet of the pebble bed. The results demonstrated that: (i) the pressure drop significantly increases with decreasing the pebbles diameter, (ii) for the same superficial velocity, the pressure drop is directly proportional to the inlet pressure, and (iii) predictions of Ergun's equation agree well with the experimental results. The measured pressure drop for the lithium orthosilicate pebble bed will support the design of the purge gas system for the HCPB.

  9. Analysis the mixtures of polyphenyls by gas chromatrogaphie. 1.- Area response for biphenyl and terphenyls relative to triphenylmethane

    Perez Garcia, M.

    1966-01-01

    The relative performances of the thermal conductivity and flame ionization detectors towards triphenylmethane were investigated for each one of the components of biphenyl of biphenyl and terphenyl mixtures. The influence of the concentration of the considered compound as well as the influence derived from the present of all other components on the above-mentioned relative performance were studied. A 2 m long column filled with 50-70 mesh stomacher containing 20% apiezon L was used to carry out the study with the thermal conductivity detector by keeping the column at 300 degree centigree using helium gas as carrier. (Author) 13 refs

  10. Hydrogen and helium trapping in tungsten deposition layers formed by RF plasma sputtering

    Kazunari Katayama; Kazumi Imaoka; Takayuki Okamura; Masabumi Nishikawa

    2006-01-01

    Understanding of tritium behavior in plasma facing materials is an important issue for fusion reactor from viewpoints of fuel control and radiation safety. Tungsten is used as a plasma facing material in the divertor region of ITER. However, investigation of hydrogen isotope behavior in tungsten deposition layer is not sufficient so far. It is also necessary to evaluate an effect of helium on a formation of deposition layer and an accumulation of hydrogen isotopes because helium generated by fusion reaction exists in fusion plasma. In this study, tungsten deposition layers were formed by sputtering method using hydrogen and helium RF plasma. An erosion rate and a deposition rate of tungsten were estimated by weight measurement. Hydrogen and helium retention were investigated by thermal desorption method. Tungsten deposition was performed using a capacitively-coupled RF plasma device equipped with parallel-plate electrodes. A tungsten target was mounted on one electrode which is supplied with RF power at 200 W. Tungsten substrates were mounted on the other electrode which is at ground potential. The plasma discharge was continued for 120 hours where pressure of hydrogen or helium was controlled to be 10 Pa. The amounts of hydrogen and helium released from deposition layers was quantified by a gas chromatograph. The erosion rate of target tungsten under helium plasma was estimated to be 1.8 times larger than that under hydrogen plasma. The deposition rate on tungsten substrate under helium plasma was estimated to be 4.1 times larger than that under hydrogen plasma. Atomic ratio of hydrogen to tungsten in a deposition layer formed by hydrogen plasma was estimated to be 0.17 by heating to 600 o C. From a deposition layer formed by helium plasma, not only helium but also hydrogen was released by heating to 500 o C. Atomic ratios of helium and hydrogen to tungsten were estimated to be 0.080 and 0.075, respectively. The trapped hydrogen is probably impurity hydrogen

  11. Electrical insulation characteristics of liquid helium under high speed rotating field

    Ishii, I.; Fuchino, S.; Okano, M.; Tamada, N.

    1996-01-01

    Electrical breakdown behavior of liquid helium was investigated under high speed rotating field. In the development of superconducting turbine generator it is essential to get the knowledge of electrical insulation characteristics of liquid helium under high speed rotating field. When the current of the field magnet of a superconducting generator is changed, changing magnetic field generates heat in the conductor and it causes bubbles in the liquid helium around the conductor. The behavior of the bubbles is affected largely by the buoyancy which is generated by the centrifugal force. Electrical breakdown behavior of the liquid helium is strongly dependent on the gas bubbles in the liquid. Electrical breakdown voltage between electrodes was measured in a rotating cryostat with and without heater input for bubble formation. Decrease of the breakdown voltage by the heater power was smaller in the rotating field than that in the non rotating field

  12. Helium induced degradation in the weldability of an austenitic stainless steel

    Lin, H.T.; Goods, S.H.; Grossbeck, M.L.; Chinl, B.A.

    1988-01-01

    Autogenous gas tungsten arc welding was performed on He-doped type 316 stainless steel. Helium was uniformly implanted in the material using the ''tritium trick'' to levels of 27 and 105 appm. Severe intergranular cracking occurred in both fusion and heat-affected zones. Microstructural observations of fusion zone indicated that the pore size, degree of porosity, and tendency to form cracks increased with increasing helium concentration. Scanning electron microscopy showed that cracking in He-doped materials was due to the precipitation of helium bubbles on grain boundaries and dentrite interfaces. Results of the present study demonstrate that the use of conventional welding techniques to repair materials degraded by exposure to radiation may be difficult if the irradiation results in the generation of even rather small amounts of helium. 23 refs., 9 figs., 2 tabs

  13. High Temperature Operational Experiences of Helium Experimental Loop

    Kim, Chan Soo; Hong, Sung-Deok; Kim, Eung-Seon; Kim, Min Hwan

    2015-01-01

    The development of high temperature components of VHTR is very important because of its higher operation temperature than that of a common light water reactor and high pressure industrial process. The development of high temperature components requires the large helium loop. Many countries have high temperature helium loops or a plan for its construction. Table 1 shows various international state-of-the-art of high temperature and high pressure gas loops. HELP performance test results show that there is no problem in operation of HELP at the very high temperature experimental condition. These experimental results also provide the basic information for very high temperature operation with bench-scale intermediate heat exchanger prototype in HELP. In the future, various heat exchanger tests will give us the experimental data for GAMMA+ validation about transient T/H behavior of the IHX prototype and the optimization of the working fluid in the intermediate loop

  14. The maintenance record of the KSTAR helium refrigeration system

    Moon, K. M.; Joo, J. J.; Kim, N. W. [National Fusion Research Institute, Daejeon (Korea, Republic of); and others

    2013-12-15

    Korea Superconducting Tokamak Advanced Research (KSTAR) has a helium refrigeration system (HRS) with the cooling capacity of 9 kW at 4.5 K. Main cold components are composed of 300 tons of superconducting (SC) magnets, main cryostat thermal shields, and SC current feeder system. The HRS comprises six gas storage tanks, a liquid nitrogen tank, the room temperature compression sector, the cold box (C/B), the 1st stage helium distribution box (DB no.1), the PLC base local control system interconnected to central control tower and so on. Between HRS and cold components, there is another distribution box (DB#2) nearby the KSTAR device. The entire KSTAR device was constructed in 2007 and has been operated since 2008. This paper will present the maintenance result of the KSTAR HRS during the campaign and discuss the operation record and maintenance history of the KSTAR HRS.

  15. Design study on the helium engineering demonstration loop (HENDEL)

    Aochi, Tetsuo; Yasuno, Takehiko; Muto, Yasushi; Suzuki, Kunihiko

    1977-11-01

    Four reference studies made on Helium Engineering Demonstration Loop (HENDEL) are described. HENDEL is used in confirmation of the designs of VHTR components such as reactor structure, core structure, intermediate heat exchanger and piping. It consists of mother loop, adapter section and four test sections for fuel stack, reactor support and insulation structure, core structure and high temperature heat transfer component respectively. System and component designs of the mother and adapter section and preliminary designs of the four test sections are shown. And, the plans of operation, instrumentation, control, safety, utilities (electricity, cooling water and helium gas) and construction schedule of HENDEL and research and development of the test sections are also briefed. (auth.)

  16. High-density equation of state for helium and its application to bubbles in solids

    Wolfer, W.G.

    1980-06-01

    Helium, produced by transmutations or injected, causes bubble formation in solids at elevated temperatures. For small bubbles, the gas pressure required to balance the surface tension reaches values which far exceed those obtainable in experiments to measure the equation of state for helium gas. Therefore, empirical gas laws cannot be considered applicable to the fluid-like densities existing in small bubbles. In order to remedy this situation, an equation of state for helium was developed from the theory of the liquid state. At very low densities, this theoretically derived equation of state agrees with experimental results. For high densities, however, gas pressures are predicted which are significantly higher than those derived from the ideal gas law, but also significantly lower than pressures obtained with the van der Waals law. When applied to equilibrium bubbles in solids, it is found that the high-density equation of state leads to less bubble swelling than the van der Waals law, but more than the ideal gas law. Furthermore, the number of helium atoms in equilibrium bubbles is nearly independent of temperature

  17. Experimental investigations of helium cryotrapping by argon frost

    Mack, A.; Perinic, D.; Murdoch, D.; Boissin, J.C.

    1992-01-01

    At the Karlsruhe Nuclear Research Centre (KfK) cryopumping techniques are being investigated by which the gaseous exhausts from the NET/ITER reactor can be pumped out during the burn-and dwell-times. Cryosorption and cryotrapping are techniques which are suitable for this task. It is the target of the investigations to test the techniques under NET/ITER conditions and to determine optimum design data for a prototype. They involve measurement of the pumping speed as a function of the gas composition, gas flow and loading condition of the pump surfaces. The following parameters are subjected to variations: Ar/He ratio, specific helium volume flow rate, cryosurface temperature, process gas composition, impurities in argon trapping gas, three-stage operation and two-stage operation. This paper is a description of the experiments on argon trapping techniques started in 1990. Eleven tests as well as the results derived from them are described

  18. Simulation of kinetic processes in the nuclear-excited helium non-ideal dusty plasma

    Budnik, A.P.; Kosarev, V.A.; Rykov, V.A.; Fortov, V.E.; Vladimirov, V.I.; Deputatova, L.V.

    2009-01-01

    The paper is devoted to the studying of kinetic processes in the nuclear-excited plasma of the helium gas with the fine uranium (or its chemical compounds) particles admixture. A new theoretical model for the mathematical simulation of the kinetic processes in dusty plasma of helium gas was developed. The main goal of this investigation is to determine possibilities of a creation of non-ideal dusty plasma, containing nano- and micro-particles, and excited by fission fragments (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. The condition of existence of the Bose-Einstein condensation in the superfluid liquid helium

    Minasyan, V.N.; Samoilov, V.N.

    2010-01-01

    The condition for the Bose-Einstein transition in the superfluid liquid helium is presented due to the formation of a free neutron spinless pairs in a liquid helium-dilute neutron gas mixture. We show that the term, of the interaction between the excitations of the Bose gas and the density modes of the neutron, meditate an attractive interaction via the neutron modes, which in turn leads to a bound state on a spinless neutron pair. The lambda transition point is defined by a condition for the Bose-Einstein transition, which transforms reflected neutron pair modes to single neutron modes.

  20. A three-dimensional meso-scale modeling for helium bubble growth in metals

    Suzudo, T.; Kaburaki, H.; Wakai, E.

    2007-01-01

    A three-dimensional meso-scale computer model using a Monte-Carlo simulation method has been proposed to simulate the helium bubble growth in metals. The primary merit of this model is that it enables the visual comparison between the microstructure observed by the TEM imaging and those by calculations. The modeling is so simple that one can control easily the calculation by tuning parameters. The simulation results are confirmed by the ideal gas law and the capillary relation. helium bubble growth, meso-scale modeling, Monte-Carlo simulation, the ideal gas law and the capillary relation. (authors)

  1. Fracture detection and groundwater flow characterization in poorly exposed ground using helium and radon in soil gases

    Gascoyne, M.; Wuschke, D.M.

    1991-05-01

    Radon and helium in soil gases have been used to identify locations of groundwater discharge and the presence of fractures outcropping beneath overburden in two areas near the Underground Research Laboratory (URL), Lac du Bonnet, Manitoba, Canada. In particular, groundwater discharge from a known, inclined fracture zone at the URL was clearly identified by a helium excess in overlying soil gases. A model was developed to describe gas phase flow in bedrock and overburden at this location, from gas injection in an adjacent borehole. Predictions were made of gas transport pathway and breakthrough time at the surface, in preparation for a gas injection test

  2. Helium diffusion in nickel at high temperatures

    Philipps, V.

    1980-09-01

    Helium has been implanted at certain temperatures between 800 and 1250 0 C into single and polycrystalline Ni-samples with implantation depths between 15 and 90 μm. Simultaneously the helium reemission from the sample is measured by a mass-spectrometer. It has been shown that the time dependence of the observed reemission rate is governed by volume diffusion of the helium. Measuring this time dependence as a function of temperature the helium diffusion constant has been determined. The He-diffusion is interpreted as a interstitial diffusion hindered by thermal vacancies. Depending on the implantation depth more or less of the implanted helium remains in the sample and forms large helium bubbles. (orig./GSCH)

  3. Test of a cryogenic helium pump

    Lue, J.W.; Miller, J.R.; Walstrom, P.L.; Herz, W.

    1981-01-01

    The design of a cryogenic helium pump for circulating liquid helium in a magnet and the design of a test loop for measuring the pump performance in terms of mass flow vs pump head at various pump speeds are described. A commercial cryogenic helium pump was tested successfully. Despite flaws in the demountable connections, the piston pump itself has performed satisfactorily. A helium pump of this type is suitable for the use of flowing supercritical helium through Internally Cooled Superconductor (ICS) magnets. It has pumped supercritical helium up to 7.5 atm with a pump head up to 2.8 atm. The maximum mass flow rate obtained was about 16 g/s. Performance of the pump was degraded at lower pumping speeds

  4. Backscattered Helium Spectroscopy in the Helium Ion Microscope: Principles, Resolution and Applications

    van Gastel, Raoul; Hlawacek, G.; Dutta, S.; Poelsema, Bene

    2015-01-01

    We demonstrate the possibilities and limitations for microstructure characterization using backscattered particles from a sharply focused helium ion beam. The interaction of helium ions with matter enables the imaging, spectroscopic characterization, as well as the nanometer scale modification of

  5. Helium leak testing methods in nuclear applications

    Ahmad, Anis

    2004-01-01

    Helium mass-spectrometer leak test is the most sensitive leak test method. It gives very reliable and sensitive test results. In last few years application of helium leak testing has gained more importance due to increased public awareness of safety and environment pollution caused by number of growing chemical and other such industries. Helium leak testing is carried out and specified in most of the critical area applications like nuclear, space, chemical and petrochemical industries

  6. Laser spectroscopy of Ag atoms in liquid helium and gaseous helium at low temperatures

    Hui, Q.; Persson, J. L.; Jakubek, Z. J.; Takami, M.

    1998-01-01

    Neutral Ag atoms are dispersed in liquid and gaseous helium by laser ablation and dissociation. Following the excitation of the D2 line, a broad emission band is observed to the red side of the D1 emission line. This band is assigned to the A 2 Π 3/2 → X 2 Σ + bound-free transition of the AgHe 2 exciplex. The assignment has been confirmed by an ab initio calculation on the AgHe 2 complex. The temperature and the pressure dependences of the D1 emission and the broad emission in the gas phase indicate that the 4d 9 5s 2 2 D 5/2 level may play an important role in the 5p 2 P 3/2 → 5p 2 1/2 non-radiative relaxation and the exciplex formation processes

  7. Adsorption of krypton from helium by low temperature charcoal

    Cooper, M.H.; Simmons, C.R.; Taylor, G.R.

    1975-01-01

    Adsorption of krypton from helium by charcoal at temperatures from -100 0 C to -140 0 C was experimentally investigated to verify adsorption system design methods and to determine effects of regeneration for the Gas Purification System of the Liquid-Metal Fast Breeder Reactor. Helium with two krypton concentrations, traced by krypton-85 at 0.0044 μCi/cm 3 , was passed through a 1/2-inch diameter, three-inch long trap packed with coconut charcoal. Breakthrough curves were measured by continuously recording the activity of the effluent gas using a sampler with a krypton-85 detection limit of about 5 x 10 -7 μCi/cm 3 . Experimental breakthrough curves with continuous feed for both concentrations and for superficial gas velocities of 5 to 28 cm/sec were closely fitted when the pore diffusion term was omitted from the Anzelius linear equilibrium adsorption model indicating that the adsorption process for this system was controlled by gas phase mass transport kinetics. Adsorption capacities determined in these experiments at -140 0 C agreed closely with published data. A discontinuity, however, was observed in the krypton adsorption coefficient between -100 and -120 0 C. This discontinuity may be caused by capillary condensation of krypton in the charcoal pores. Breakthrough times for pulse experiments at 400 ppM (vol.) krypton concentration were several times greater than breakthrough for continuous feed experiments at equivalent conditions. The differences in breakthrough times indicate that the adsorption isotherms are non-linear in this concentration range. Regeneration experiments showed that purging with helium at room temperature for 16 hours was inadequate, since lower breakthrough times were obtained after this treatment. Regeneration under vacuum at 100 0 C or 200 0 C for 16 hours resulted in satisfactory regeneration (i.e., no reduction in breakthrough times occurred in subsequent runs). (U.S.)

  8. Direct Analysis of Organic Compounds in Liquid Using a Miniature Photoionization Ion Trap Mass Spectrometer with Pulsed Carrier-Gas Capillary Inlet.

    Lu, Xinqiong; Yu, Quan; Zhang, Qian; Ni, Kai; Qian, Xiang; Tang, Fei; Wang, Xiaohao

    2017-08-01

    A miniature ion trap mass spectrometer with capillary direct sampling and vacuum ultraviolet photoionization source was developed to conduct trace analysis of organic compounds in liquids. Self-aspiration sampling is available where the samples are drawn into the vacuum chamber through a capillary with an extremely low flow rate (less than 1 μL/min), which minimizes sample consumption in each analysis to tens of micrograms. A pulsed gas-assisted inlet was designed and optimized to promote sample transmission in the tube and facilitate the cooling of ions, thereby improving instrument sensitivity. A limit of detection of 2 ppb could be achieved for 2,4-dimethylaniline in a methanol solution. The sampling system described in the present study is specifically suitable for a miniature photoionization ion trap mass spectrometer that can perform rapid and online analysis for liquid samples. Graphical Abstract ᅟ.

  9. New helium spectrum variable and a new helium-rich star

    Walborn, N.R.

    1974-01-01

    HD 184927, known previously as a helium-rich star, has been found to have a variable helium spectrum; the equivalent widths of five He I lines are larger by an average of 46 percent on a 1974 spectrogram than on one obtained with the same equipment in 1970. HD 186205 has been found to be a new, pronounced helium-rich star. (auth)

  10. Helium transfer line installation details.

    G. Perinic

    2007-01-01

    A particularity of the 32 m long four in one helium transfer line in between the cold box in USC55 and the cavern UX5 is the fact that the transfer line passes through a hole in the crane rail support beam. In order to ensure the alignment of the suspension rail in the interconnecting tunnel with the hole in the rail support as well as the connection points at both ends required precise measurements of the given geometries as well as the installation of a temporary target for the verification of the theoretical predictions.

  11. Helium bubble bursting in tungsten

    Sefta, Faiza; Juslin, Niklas; Wirth, Brian D.

    2013-01-01

    Molecular dynamics simulations have been used to systematically study the pressure evolution and bursting behavior of sub-surface helium bubbles and the resulting tungsten surface morphology. This study specifically investigates how bubble shape and size, temperature, tungsten surface orientation, and ligament thickness above the bubble influence bubble stability and surface evolution. The tungsten surface is roughened by a combination of adatom “islands,” craters, and pinholes. The present study provides insight into the mechanisms and conditions leading to various tungsten topology changes, which we believe are the initial stages of surface evolution leading to the formation of nanoscale fuzz

  12. Improvement of In-Flight Alumina Spheroidization Process Using a Small Power Argon DC-RF Hybrid Plasma Flow System by Helium Mixture

    Takana, Hidemasa; Jang, Juyong; Igawa, Junji; Nakajima, Tomoki; Solonenko, Oleg P.; Nishiyama, Hideya

    2011-03-01

    For the further improvement of in-flight alumina spheroidization process with a low-power direct-current radiofrequency (DC-RF) hybrid plasma flow system, the effect of a small amount of helium gas mixture in argon main gas and also the effect of increasing DC nozzle diameter on powder spheroidization ratio have been experimentally clarified with correlating helium gas mixture percentage, plasma enthalpy, powder in-flight velocity, and temperature. The alumina spheroidization ratio increases by helium gas mixture as a result of enhancement of plasma enthalpy. The highest spheroidization ratio is obtained by 4% mixture of helium in central gas with enlarging nozzle diameter from 3 to 4 mm, even under the constant low input electric power given to a DC-RF hybrid plasma flow system.

  13. Research on energy efficiency design index for sea-going LNG carriers

    Lin, Yan; Yu, Yanyun; Guan, Guan

    2014-12-01

    This paper describes the characteristics of liquefied natural gas (LNG) carriers briefly. The LNG carrier includes power plant selection, vapor treatment, liquid cargo tank type, etc. Two parameters—fuel substitution rate and recovery of boil of gas (BOG) volume to energy efficiency design index (EEDI) formula are added, and EEDI formula of LNG carriers is established based on ship EEDI formula. Then, based on steam turbine propulsion device of LNG carriers, mathematical models of LNG carriers' reference line value are established in this paper. By verification, the EEDI formula of LNG carriers described in this paper can provide a reference for LNG carrier EEDI calculation and green shipbuilding.

  14. Dynamics of vortex assisted metal condensation in superfluid helium.

    Popov, Evgeny; Mammetkuliyev, Muhammet; Eloranta, Jussi

    2013-05-28

    Laser ablation of copper and silver targets immersed in bulk normal and superfluid (4)He was studied through time-resolved shadowgraph photography. In normal fluid, only a sub-millimeter cavitation bubble is created and immediate formation of metal clusters is observed within a few hundred microseconds. The metal clusters remain spatially tightly focused up to 15 ms, and it is proposed that this observation may find applications in particle image velocimetry. In superfluid helium, the cavitation bubble formation process is distinctly different from the normal fluid. Due to the high thermal conductivity and an apparent lag in the breakdown of superfluidity, about 20% of the laser pulse energy was transferred directly into the liquid and a large gas bubble, up to several millimeters depending on laser pulse energy, is created. The internal temperature of the gas bubble is estimated to exceed 9 K and the following bubble cool down period therefore includes two separate phase transitions: gas-normal liquid and normal liquid-superfluid. The last stage of the cool down process was assigned to the superfluid lambda transition where a sudden formation of large metal clusters is observed. This is attributed to high vorticity created in the volume where the gas bubble previously resided. As shown by theoretical bosonic density functional theory calculations, quantized vortices can trap atoms and dimers efficiently, exhibiting static binding energies up to 22 K. This, combined with hydrodynamic Bernoulli attraction, yields total binding energies as high as 35 K. For larger clusters, the static binding energy increases as a function of the volume occupied in the liquid to minimize the surface tension energy. For heliophobic species an energy barrier develops as a function of the cluster size, whereas heliophilics show barrierless entry into vortices. The present theoretical and experimental observations are used to rationalize the previously reported metal nanowire assembly in

  15. Helium Exhaust Studies in H-Mode Discharges in the DIII-D Tokamak Using an Argon-Frosted Divertor Cryopump

    Wade, M.R.; Hillis, D.L.; Hogan, J.T.; Mahdavi, M.A.; Maingi, R.; West, W.P.; Brooks, N.H.; Burrell, K.H.; Groebner, R.J.; Jackson, G.L.; Klepper, C.C.; Laughon, G.; Menon, M.M.; Mioduszewski, P.K.

    1995-01-01

    The first experiments demonstrating exhaust of thermal helium in a diverted, H-mode deuterium plasma have been performed on the DIII-D tokamak. The helium, introduced via gas puffing, is observed to reach the plasma core, and then is readily removed from the plasma with a time constant of ∼10--20 energy-confinement times by an in-vessel cryopump conditioned with argon frosting. Detailed analysis of the helium profile evolution suggests that the exhaust rate is limited by the exhaust efficiency of the pump (∼5%) and not by the intrinsic helium-transport properties of the plasma

  16. Helium-plasma heating with a powerful proton beam for spectroscopic applications

    Arteev, M.S.; Kuznetsov, A.A.; Sulakshin, S.S.

    1986-01-01

    In this work the authors consider an ion gun which was especially developed for producing a gas plasma and report on the details of an experiment on (ELLIGIBLE) plasma spectroscopy. The current density of the proton beam was measured in the experiments on the axis of the gas tube with the aid of a collimating current collector with the wave impedance of a 75 omega cable. The ion gun was tested in the excitation of a helium plasma. Extremely pure helium with a pressure P = (0.2-1).10 5 Pa was employed. The proton gun which was developed satifies the requirements of spectroscopic plasma experiments and makes it possible to excite a plasma of inert gases under atmospheric pressure over a length of up to 100 cm, with the plasma having high homogeneity and stability. They obtained first results of spectroscopic measurements of the electron concentration of a helium plasma and the results agree with the theoretical predictions

  17. Online helium inventory monitoring of JLab cryogenic systems

    Hasan, N.; Knudsen, P.; Wright, M.

    2017-12-01

    There are five cryogenic plants at Jefferson Lab which support the LINAC, experiment hall end-stations and test facility. The majority of JLab’s helium inventory, which is around 15 tons, is allocated in the LINAC cryo-modules, with the majority of the balance of helium distributed at the cryogenic-plant level mainly as stored gas and liquid for stable operation. Due to the organic evolution of the five plants and independent actions within the experiment halls, the traditional inventory management strategy suffers from rapid identification of potential leaks. This can easily result in losses many times higher than the normally accepted (average) loss rate. A real-time program to quickly identify potential excessive leakage was developed and tested. This program was written in MATLAB© for portability, easy diagnostics and modification. It interfaces directly with EPICS to access the cryogenic system state, and with and NIST REFPROP© for real fluid properties. This program was validated against the actual helium offloaded into the system. The present paper outlines the details of the inventory monitoring program, its validation and a sample of the achieved results.

  18. Modular helium reactor for non-electric applications

    Shenoy, A.

    1997-01-01

    The high temperature gas-cooled Modular Helium Reactor (MHR) is an advanced, high efficiency reactor system which can play a vital role in meeting the future energy needs of the world by contributing not only to the generation of electric power, but also the non-electric energy traditionally served by fossil fuels. This paper summarizes work done over 20 years, by several people at General Atomics, how the Modular Helium Reactor can be integrated to provide different non-electric applications during Process Steam/Cogeneration for industrial application, Process Heat for transportation fuel development and Hydrogen Production for various energy applications. The MHR integrates favorably into present petrochemical and primary metal process industries, heavy oil recovery, and future shale oil recovery and synfuel processes. The technical fit of the Process Steam/Cogeneration Modular Helium Reactor (PS/C-MHR) into these processes is excellent, since it can supply the required quantity and high quality of steam without fossil superheating. 12 refs, 25 figs, 2 tabs

  19. Four-body conversion of atomic helium ions

    de Vries, C.P.; Oskam, H.J.

    1980-01-01

    The conversion of atomic helium ions into molecular ions was studied in pure helium and in helium-neon mixtures containing between 0.1 at. % and 50 at. % neon. The experiments showed that the termolecular conversion reaction, He + +2He → He 2 + +He, is augmented by the four-body conversion reaction He + +3He → products, where the products could include either He 2 + or He 3 + ions. Conversion rate coefficients of (5.7 +- 0.8) x 10 -32 cm 6 sec -1 and (2.6 +- 0.4) x 10 -49 cm 9 sec -1 were found for the termolecular and four-body conversion reactions, respectively. In addition, rate coefficients for the following Ne + conversion reactions were measured: Ne + +He+He → (HeNe) + +He, (2.3 +- 0.1) x 10 -32 cm 6 sec -1 ; Ne + +He+Ne → (HeNe) + +Ne or Ne 2 + +He, (8.0 +- 0.8) x 10 -32 cm 6 sec -1 ; and Ne + +Ne+Ne → Ne 2 + +Ne, (5.1 +- 0.3) x 10 -32 cm 6 sec -1 . All rate coefficients are at a gas temperature of 295 K

  20. The thermodynamic properties of normal liquid helium 3

    Modarres, M.; Moshfegh, H. R.

    2009-09-01

    The thermodynamic properties of normal liquid helium 3 are calculated by using the lowest order constrained variational (LOCV) method. The Landau Fermi liquid model and Fermi-Dirac distribution function are considered as our statistical model for the uncorrelated quantum fluid picture and the Lennard-Jones and Aziz potentials are used in our truncated cluster expansion (LOCV) to calculate the correlated energy. The single particle energy is treated variationally through an effective mass. The free energy, pressure, entropy, chemical potential and liquid phase diagram as well as the helium 3 specific heat are evaluated, discussed and compared with the corresponding available experimental data. It is found that the critical temperature for the existence of the pure gas phase is about 4.90 K (4.45 K), which is higher than the experimental prediction of 3.3 K, and the helium 3 flashing temperature is around 0.61 K (0.50 K) for the Lennard-Jones (Aziz) potential.