Sample records for based shielding materials

  1. Carbohydrate based materials for gamma radiation shielding (United States)

    Tabbakh, F.; Babaee, V.; Naghsh-Nezhad, Z.


    Due to the limitation in using lead as a shielding material for its toxic properties and limitation in abundance, price or non-flexibility of other commonly used materials, finding new shielding materials and compounds is strongly required. In this conceptual study carbohydrate based compounds were considered as new shielding materials. The simulation of radiation attenuation is performed using MCNP and Geant4 with a good agreement in the results. It is found that, the thickness of 2 mm of the proposed compound may reduce up to 5% and 50% of 1 MeV and 35 keV gamma-rays respectively in comparison with 15% and 100% for the same thickness of lead.

  2. Neutron shielding material based on colemanite and epoxy resin. (United States)

    Okuno, Koichi


    In recent years, there has been a need for compact shielding design such as self-shielding of a PET cyclotron or upgradation of radiation machinery in existing facilities. In these cases, high performance shielding materials are needed. Concrete or polyethylene have been used for a neutron shield. However, for compact shielding, they fall short in terms of performance or durability. Therefore, a new type of neutron shielding material based on epoxy resin and colemanite has been developed. Slab attenuation experiments up to 40 cm for the new shielding material were carried out using a 252Cf neutron source. Measurement was carried out using a REM-counter, and compared with calculation. The results show that the shielding performance is better than concrete and polyethylene mixed with 10 wt% boron oxide. From the result, we confirmed that the performance of the new material is suitable for practical use.

  3. New gadolinium based glasses for gamma-rays shielding materials

    Energy Technology Data Exchange (ETDEWEB)

    Kaewjang, S.; Maghanemi, U.; Kothan, S. [Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chang Mai University, Chang Mai 50200 (Thailand); Kim, H.J. [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Limkitjaroenporn, P. [Center of Excellence in Glass Technology and Materials Science (CEGM), Nakhon Pathom Rajabhat University, Nakhon Pathom 73000 (Thailand); Kaewkhao, J., E-mail: [Center of Excellence in Glass Technology and Materials Science (CEGM), Nakhon Pathom Rajabhat University, Nakhon Pathom 73000 (Thailand)


    Highlights: • Gd{sub 2}O{sub 3} based glasses have been fabricated and investigated radiation shielding properties between 223 and 662 keV. • Density of the glass increases with increasing of Gd{sub 2}O{sub 3.} • All the glasses of Gd{sub 2}O{sub 3} compositions studied had been shown lower HVL than X-rays shielding window. • Prepared glasses to be utilized as radiation shielding material with Pb-free advantage. • This work is the first to reports on radiation shielding properties of Gd{sub 2}O{sub 3} based glass matrices. - Abstract: In this work, Gd{sub 2}O{sub 3} based glasses in compositions (80−x)B{sub 2}O{sub 3}-10SiO{sub 2}-10CaO-xGd{sub 2}O{sub 3} (where x = 15, 20, 25, 30 and 35 mol%) have been fabricated and investigated for their radiation shielding, physical and optical properties. The density of the glass was found to increase with the increasing of Gd{sub 2}O{sub 3} concentration. The experimental values of mass attenuation coefficients (μ{sub m}), effective atomic number (Z{sub eff}) and effective electron densities (N{sub e}) of the glasses were found to increase with the increasing of Gd{sub 2}O{sub 3} concentration and also with the decreasing of photon energy from 223 to 662 keV. The glasses of all Gd{sub 2}O{sub 3} compositions studied have been shown with lower HVL values in comparison to an X-rays shielding window, ordinary concrete and commercial window; indicating their potential as radiation shielding materials with Pb-free advantage. Optical spectra of the glasses in the present study had been shown with light transparency; an advantage when used as radiation shielding materials.

  4. Radiation Shielding Materials (United States)

    Adams, James H., Jr.; Rose, M. Franklin (Technical Monitor)


    NASA has relied on the materials to provide radiation shielding for astronauts since the first manned flights. Until very recently existing materials in the structure of manned spacecraft as well as the equipment and consumables onboard have been taken advantage of for radiation shielding. With the advent of the International Space Station and the prospect of extended missions to the Moon or Mars, it has been found that the materials, which were included in the spacecraft for other reasons, do not provide adequate shielding. For the first time materials are being added to manned missions solely to improve the radiation shielding. It is now recognized that dual use materials must be identified/developed. These materials must serve a purpose as part of the spacecraft or its cargo and at the same time be good shielding. This paper will review methods for evaluating the radiation shielding effectiveness of materials and describe the character of materials that have high radiation shielding effectiveness. Some candidate materials will also be discussed.

  5. Ultra high molecular weight polyethylene as a base material for shielding cosmic radiation in aerospace applications

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Marlon A., E-mail: [Instituto de Estudos Avancados (IEAv), Sao Jose dos Campos, SP (Brazil). Divisao de Fisica Aplicada; Goncalez, Odair L. [Instituto Tecnologico de Aeronautica (PG/CTE/ITA), Sao Jose dos Campos, SP (Brazil). Programa de Pos-Graduacao em Ciencias e Tecnologias Espaciais


    Materials with high content of hydrogen have good properties of shielding against the effects of cosmic rays (CR) because are less effective than materials with high nuclear masses in the generation of secondary radiation. Beside the Aluminum, Polyethylene has been used as a reference and as a base material for composites applied in structures and in shielding of ionizing radiation for aerospace applications. Ultra high molecular weight polyethylene (UHMWPE), pure and doped 10% by mass with cadmium chloride, had its shielding properties for CR evaluated in this paper. Methodology used was based in conventional radioactive sources employed on simple geometries experiments and then computational simulation for isotropic fluxes of cosmic-ray high energy particles. Transmission experiments were performed with a3.7GBq (100 mCi){sup 241}Am-Be neutron source and a set of conventional calibration gamma radiation sources. Samples were characterized according to their gamma total attenuation coefficients from 59 to 1,408 keV, dose deposition curve for {sup 60}Co gamma-rays, fast neutron transmission coefficient, generation and self-absorption of thermal neutrons as well as their generation of internal cascades of secondary electrons and gamma-rays by nuclear interactions of fast neutrons with shielding material. Main effects of the additive in the polyethylene base were the most effective removal of gamma radiation and of secondary electrons with energies below 200 keV, the reduction of the albedo as well as the thermal neutrons transmission. Dose reduction due to primary CR were not significant, since the largest contribution to the doses due to high energy ionizing particles transmitted and, also, due to secondary radiation with energy above 1 MeV produced in shielding. (author)

  6. New Materials for EMI Shielding (United States)

    Gaier, James R.


    Graphite fibers intercalated with bromine or similar mixed halogen compounds have substantially lower resistivity than their pristine counterparts, and thus should exhibit higher shielding effectiveness against electromagnetic interference. The mechanical and thermal properties are nearly unaffected, and the shielding of high energy x-rays and gamma rays is substantially increased. Characterization of the resistivity of the composite materials is subtle, but it is clear that the composite resistivity is substantially lowered. Shielding effectiveness calculations utilizing a simple rule of mixtures model yields results that are consistent with available data on these materials.

  7. Material Effectiveness for Radiation Shielding (United States)


    Materials with a smaller mean atomic mass, such as lithium (Li) hydride and polyethylene, make the best radiation shields for astronauts. The materials have a higher density of nuclei and are better able to block incoming radiation. Also, they tend to produce fewer and less dangerous secondary particles after impact with incoming radiation.

  8. Neutron Shielding Effectiveness of Multifunctional Composite Materials (United States)


    shielded fast neutrons more effectively than the other materials overall, but the sample with boron shielded ...the materials will shield against fast neutrons . 3.2 Assumptions With the information and specifications originally provided by the manufacturer conduct fast foil activation experiments to determine the relative difference in the amount of neutrons shielded by the materials . This

  9. Space Shielding Materials for Prometheus Application

    Energy Technology Data Exchange (ETDEWEB)

    R. Lewis


    At the time of Prometheus program restructuring, shield material and design screening efforts had progressed to the point where a down-selection from approximately eighty-eight materials to a set of five ''primary'' materials was in process. The primary materials were beryllium (Be), boron carbide (B{sub 4}C), tungsten (W), lithium hydride (LiH), and water (H{sub 2}O). The primary materials were judged to be sufficient to design a Prometheus shield--excluding structural and insulating materials, that had not been studied in detail. The foremost preconceptual shield concepts included: (1) a Be/B{sub 4}C/W/LiH shield; (2) a Be/B{sub 4}C/W shield; (3) and a Be/B{sub 4}C/H{sub 2}O shield. Since the shield design and materials studies were still preliminary, alternative materials (e.g., {sup nal}B or {sup 10}B metal) were still being screened, but at a low level of effort. Two competing low mass neutron shielding materials are included in the primary materials due to significant materials uncertainties in both. For LiH, irradiation-induced swelling was the key issue, whereas for H{sub 2}O, containment corrosion without active chemistry control was key, Although detailed design studies are required to accurately estimate the mass of shields based on either hydrogenous material, both are expected to be similar in mass, and lower mass than virtually any alternative. Unlike Be, W, and B{sub 4}C, which are not expected to have restrictive temperature limits, shield temperature limits and design accommodations are likely to be needed for either LiH or H{sub 2}O. The NRPCT focused efforts on understanding swelting of LiH, and observed, from approximately fifty prior irradiation tests, that either casting ar thorough out-gassing should reduce swelling. A potential contributor to LiH swelling appears to be LiOH contamination due to exposure to humid air, that can be eliminated by careful processing. To better understand LiH irradiation performance and

  10. Detection of Shielded Special Nuclear Material With a Cherenkov-Based Transmission Imaging System (United States)

    Rose, Paul; Erickson, Anna; Mayer, Michael; Jovanovic, Igor


    Detection of shielded special nuclear material, SSNM, while in transit, offers a unique challenge. Typical cargo imaging systems are Bremsstrahlung-based and cause an abundance of unnecessary signal in the detectors and doses to the cargo contents and surroundings. Active interrogation with dual monoenergetic photons can unveil the illicit material when coupled with a high-contrast imaging system while imparting significantly less dose to the contents. Cherenkov detectors offer speed, resilience, inherent energy threshold rejection, directionality and scalability beyond the capability of most scintillators. High energy resolution is not a priority when using two well separated gamma rays, 4.4 and 15.1 MeV, generated from low energy nuclear reactions such as 11B(d,n- γ)12C. These gamma rays offer a measure of the effective atomic number, Z, of the cargo by taking advantage of the large difference in photon interaction cross sections, Compton scattering and pair production. This imaging system will be coupled to neutron detectors to provide unique signature of SNM by monitoring delayed neutrons. Our experiments confirm that the Cherenkov imaging system can be used with the monoenergetic source to relate transmission and atomic number of the scanned material.

  11. Radiation Shielding Materials and Containers Incorporating Same

    Energy Technology Data Exchange (ETDEWEB)

    Mirsky, Steven M.; Krill, Stephen J.; and Murray, Alexander P.


    An improved radiation shielding material and storage systems for radioactive materials incorporating the same. The PYRolytic Uranium Compound (''PYRUC'') shielding material is preferably formed by heat and/or pressure treatment of a precursor material comprising microspheres of a uranium compound, such as uranium dioxide or uranium carbide, and a suitable binder. The PYRUC shielding material provides improved radiation shielding, thermal characteristic, cost and ease of use in comparison with other shielding materials. The shielding material can be used to form containment systems, container vessels, shielding structures, and containment storage areas, all of which can be used to house radioactive waste. The preferred shielding system is in the form of a container for storage, transportation, and disposal of radioactive waste. In addition, improved methods for preparing uranium dioxide and uranium carbide microspheres for use in the radiation shielding materials are also provided.

  12. Predictions for Radiation Shielding Materials (United States)

    Kiefer, Richard L.


    Radiation from galactic cosmic rays (GCR) and solar particle events (SPE) is a serious hazard to humans and electronic instruments during space travel, particularly on prolonged missions outside the Earth s magnetic fields. Galactic cosmic radiation (GCR) is composed of approx. 98% nucleons and approx. 2% electrons and positrons. Although cosmic ray heavy ions are 1-2% of the fluence, these energetic heavy nuclei (HZE) contribute 50% of the long-term dose. These unusually high specific ionizations pose a significant health hazard acting as carcinogens and also causing microelectronics damage inside spacecraft and high-flying aircraft. These HZE ions are of concern for radiation protection and radiation shielding technology, because gross rearrangements and mutations and deletions in DNA are expected. Calculations have shown that HZE particles have a strong preference for interaction with light nuclei. The best shield for this radiation would be liquid hydrogen, which is totally impractical. For this reason, hydrogen-containing polymers make the most effective practical shields. Shielding is required during missions in Earth orbit and possibly for frequent flying at high altitude because of the broad GCR spectrum and during a passage into deep space and LunarMars habitation because of the protracted exposure encountered on a long space mission. An additional hazard comes from solar particle events (SPEs) which are mostly energetic protons that can produce heavy ion secondaries as well as neutrons in materials. These events occur at unpredictable times and can deliver a potentially lethal dose within several hours to an unshielded human. Radiation protection for humans requires safety in short-term missions and maintaining career exposure limits within acceptable levels on future long-term exploration missions. The selection of shield materials can alter the protection of humans by an order of magnitude. If improperly selected, shielding materials can actually

  13. Emission of fluorescent x-radiation from non-lead based shielding materials of protective clothing: a radiobiological problem? (United States)

    Schmid, E; Panzer, W; Schlattl, H; Eder, H


    material. Even if it is uncertain whether the marked dependency of the RBE at low doses on photon energy for chromosome aberrations is also representative for late radiation effects in healthy subjects, it should be taken into account that several prospective cohort studies have shown positive associations between higher chromosome aberrations in lymphocytes of healthy subjects and increased cancer incidence. Thus, it can be concluded that any additional biological damage by radiation exposure of healthy subjects, e.g. by using certain non-lead based shielding materials of protective clothing, should be avoided.

  14. Radiation Protection Effectiveness of Polymeric Based Shielding Materials at Low Earth Orbit (United States)

    Badavi, Francis F.; Stewart-Sloan, Charlotte R.; Wilson, John W.; Adams, Daniel O.


    Correlations of limited ionizing radiation measurements onboard the Space Transportation System (STS; shuttle) and the International Space Station (ISS) with numerical simulations of charged particle transport through spacecraft structure have indicated that usage of hydrogen rich polymeric materials improves the radiation shielding performance of space structures as compared to the traditionally used aluminum alloys. We discuss herein the radiation shielding correlations between measurements on board STS-81 (Atlantis, 1997) using four polyethylene (PE) spheres of varying radii, and STS-89 (Endeavour, 1998) using aluminum alloy spheres; with numerical simulations of charged particle transport using the Langley Research Center (LaRC)-developed High charge (Z) and Energy TRaNsport (HZETRN) algorithm. In the simulations, the Galactic Cosmic Ray (GCR) component of the ionizing radiation environment at Low Earth Orbit (LEO) covering ions in the 1Radiation (AIR) measurements. With the validity of numerical simulations through correlation with PE and aluminum spheres measurements established, we further present results from the expansion of the simulations through the selection of high hydrogen content commercially available polymeric constituents such as PE foam core and Spectra fiber(Registered TradeMark) composite face sheet to assess their radiation shield properties as compared to generic PE.

  15. A Novel Radiation Shielding Material Project (United States)

    National Aeronautics and Space Administration — Radiation shielding simulations showed that epoxy loaded with 10-70% polyethylene would be an excellent shielding material against GCRs and SEPs. Milling produced an...

  16. A new radiation shielding material: Amethyst ore

    Energy Technology Data Exchange (ETDEWEB)

    Korkut, Turgay, E-mail: [Faculty of Science and Art, Department of Physics, Ibrahim Cecen University, Agri (Turkey); Korkut, Hatun [Faculty of Science and Art, Department of Physics, Ibrahim Cecen University, Agri (Turkey); Karabulut, Abdulhalik; Budak, Goekhan [Faculty of Science, Department of Physics, Atatuerk University, Erzurum (Turkey)


    This paper describes a new radiation shielding material, amethyst ore. We have determined the elemental composition of amethyst using WDXRF spectroscopy technique. To see the shielding capability of amethyst for several photon energies, these results have been used in simulation process by FLUKA Monte Carlo radiation transport code. Linear attenuation coefficients have been calculated according to the simulation results. Then, these values have been compared to a fine shielding concrete material. The results show that amethyst shields more gamma beams than concrete. This investigation is the first study about the radiation shielding properties of amethyst ore.

  17. Lithium hydride - A space age shielding material (United States)

    Welch, F. H.


    Men and materials performing in the environment of an operating nuclear reactor require shielding from the escaping neutron particles and gamma rays. For efficient shielding from gamma rays, dense, high atomic number elements such as iron, lead, or tungsten are required, whereas light, low atomic number elements such as hydrogen, lithium, or beryllium are required for efficient neutron shielding. The use of lithium hydride (LiH) as a highly efficient neutron-shielding material is considered. It contains, combined into a single, stable compound, two of the elements most effective in attenuating and absorbing neutrons.

  18. Shielding properties of composite materials based on epoxy resin with graphene nanoplates in the microwave frequency range (United States)

    Volynets, N. I.; Bychenok, D. S.; Lyubimov, A. G.; Kuzhir, P. P.; Maksimenko, S. A.; Baturkin, S. A.; Klochkov, A. Ya.; Mastrucci, M.; Micciulla, F.; Bellucci, S.


    Analysis of the electromagnetic properties of composite materials based on epoxy resin with the addition of 0.5 wt % graphene nanoplates in the frequency range of 26-37 GHz is performed. The influence of types of epoxy resin with different viscosities and the type of solvent used (ethanol, acetone) on the electromagnetic response in this frequency range are determined. It is established that the least viscous epoxy resin, Epikote 828, and solvent ethanol are most effective for creation of a shielding covering in the microwave range. Composite materials with optimal composition provide attenuation of the electromagnetic signal at a level at least 10 dB in power for a film thickness of 1.1 mm.

  19. Boron-10 loaded inorganic shielding material (United States)

    Baker, S. I.; Ryskiewicz, R. S.


    Shielding material containing Boron 10 and gadoliunium for neutron absorption has been developed to reduce interference from low energy neutrons in measurement of fission neutron spectrum using Li-6 fast neutron spectrometer.

  20. Highly Effective Electromagnetic Interference Shielding Materials based on Silver Nanowire/Cellulose Papers. (United States)

    Lee, Tae-Won; Lee, Sang-Eui; Jeong, Young Gyu


    We fabricated silver nanowire (AgNW)-coated cellulose papers with a hierarchical structure by an efficient and facile dip-coating process, and investigated their microstructures, electrical conductivity and electromagnetic interference (EMI) shielding effectiveness. SEM images confirm that AgNWs are coated dominantly on the paper surfaces, although they exist partially in the inner parts of the cellulose papers, which demonstrates that the AgNW density gradually decreases in thickness direction of the AgNW/cellulose papers. This result is supported by the anisotropic apparent electrical conductivity of the AgNW/cellulose papers depending on in-plane or thickness direction. Even for a AgNW/cellulose paper obtained by a single dip-coating cycle, the apparent electrical conductivity in the in-plane direction of 0.34 S/cm is achieved, which is far higher than the neat cellulose paper with ∼10(-11) S/cm. In addition, the apparent electrical conductivity of the papers in the in-plane direction increases significantly from 0.34 to 67.51 S/cm with increasing the number of dip-coating cycle. Moreover, although the AgNW/cellulose paper with 67.51 S/cm possesses 0.53 vol % AgNW only, it exhibits high EMI shielding performance of ∼48.6 dB at 1 GHz. This indicates that the cellulose paper structure is highly effective to form a conductive AgNW network. Overall, it can be concluded that the AgNW/cellulose papers with high flexibility and low density can be used as electrically conductive components and EMI shielding elements in advanced application areas.

  1. Cosmic Ray Interactions in Shielding Materials

    Energy Technology Data Exchange (ETDEWEB)

    Aguayo Navarrete, Estanislao; Kouzes, Richard T.; Ankney, Austin S.; Orrell, John L.; Berguson, Timothy J.; Troy, Meredith D.


    This document provides a detailed study of materials used to shield against the hadronic particles from cosmic ray showers at Earth’s surface. This work was motivated by the need for a shield that minimizes activation of the enriched germanium during transport for the MAJORANA collaboration. The materials suitable for cosmic-ray shield design are materials such as lead and iron that will stop the primary protons, and materials like polyethylene, borated polyethylene, concrete and water that will stop the induced neutrons. The interaction of the different cosmic-ray components at ground level (protons, neutrons, muons) with their wide energy range (from kilo-electron volts to giga-electron volts) is a complex calculation. Monte Carlo calculations have proven to be a suitable tool for the simulation of nucleon transport, including hadron interactions and radioactive isotope production. The industry standard Monte Carlo simulation tool, Geant4, was used for this study. The result of this study is the assertion that activation at Earth’s surface is a result of the neutronic and protonic components of the cosmic-ray shower. The best material to shield against these cosmic-ray components is iron, which has the best combination of primary shielding and minimal secondary neutron production.

  2. Novel Concepts for Radiation Shielding Materials (United States)

    Oliva-Buisson, Yvette J.


    It is critical that safety factors be maximized with respect to long duration, extraterrestrial space flight. Any significant improvement in radiation protection will be critical in ensuring the safety of crew and hardware on such missions. The project goal is to study novel concepts for radiation shielding materials that can be used for long-duration space missions. As part of this project we will investigate the use of thin films for the evaluation of a containment system that can retain liquid hydrogen and provide the necessary hydrogen density for effective shielding.

  3. Reusable shielding material for neutron- and gamma-radiation (United States)

    Calzada, Elbio; Grünauer, Florian; Schillinger, Burkhard; Türck, Harald


    At neutron research facilities all around the world radiation shieldings are applied to reduce the background of neutron and gamma radiation as far as possible in order to perform high quality measurements and to fulfill the radiation protection requirements. The current approach with cement-based compounds has a number of shortcomings: "Heavy concrete" contains a high amount of elements, which are not desired to obtain a high attenuation of neutron and/or gamma radiation (e.g. calcium, carbon, oxygen, silicon and aluminum). A shielding material with a high density of desired nuclei such as iron, hydrogen and boron was developed for the redesign of the neutron radiography facility ANTARES at beam tube 4 (located at a cold neutron source) of FRM-II. The composition of the material was optimized by help of the Monte Carlo code MCNP5. With this shielding material a considerable higher attenuation of background radiation can be obtained compared to usual heavy concretes.



    BELOUSOVA Elena Sergeevna; LYNKOV Leonid Mihailovich; MAHMOOD Mohammed Shakir; NASONOVA Natalia Viktorovna


    Modifications of shielding construction materials based on Portland cement with the addition of powder nanomaterial shungite were developed. Attenuation and re­flection of electromagnetic radiation for obtained materials were studied. Recommen­dations for using are given.

  5. Evaluation Of Shielding Efficacy Of A Ferrite Containing Ceramic Material

    Energy Technology Data Exchange (ETDEWEB)

    Verst, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)


    The shielding evaluation of the ferrite based Mitsuishi ceramic material has produced for several radiation sources and possible shielding sizes comparative dose attenuation measurements and simulated projections. High resolution gamma spectroscopy provided uncollided and scattered photon spectra at three energies, confirming theoretical estimates of the ceramic’s mass attenuation coefficient, μ/ρ. High level irradiation experiments were performed using Co-60, Cs-137, and Cf-252 sources to measure penetrating dose rates through steel, lead, concrete, and the provided ceramic slabs. The results were used to validate the radiation transport code MCNP6 which was then used to generate dose rate attenuation curves as a function of shielding material, thickness, and mass for photons and neutrons ranging in energy from 200 keV to 2 MeV.

  6. Preparation and properties of flexible flame-retardant neutron shielding material based on methyl vinyl silicone rubber

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Hao [Department of Nuclear Science & Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing (China); Tang, Xiaobin, E-mail: [Department of Nuclear Science & Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing (China); Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering (China); Ni, Minxuan; Chen, Feida; Zhang, Yun [Department of Nuclear Science & Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing (China); Chen, Da [Department of Nuclear Science & Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing (China); Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering (China); Qiu, Yunlong [ZhongXing Energy Equipment Co., LTD, Haimen Nantong (China)


    Flexible flame-retardant composites were prepared using high-functional methyl vinyl silicone rubber matrix with B{sub 4}C, hollow beads, and zinc borate (ZB) as filler materials. As filler content increased, the tensile strength, elongation, and tear strength of the composites initially increased and then decreased. The shore hardness of the composites increased with increasing filler content with a maximum value of 30 HA. The heat insulation properties of the composites with hollow beads were higher than that of the ordinary composites with the same filler mass fraction. When ZB content exceeded 12 wt%, the limit of oxygen index of the composites was higher than 27.1%. With Am–Be neutron as the test radiation source, the transmission of neutron for a 2 cm sample was only 47.8%. Powder surface modification improved the mechanical properties, thermal conductivity, flame retardancy, and neutron shielding performance of the composites, but did not affect shore hardness.

  7. Preparation and properties of flexible flame-retardant neutron shielding material based on methyl vinyl silicone rubber (United States)

    Chai, Hao; Tang, Xiaobin; Ni, Minxuan; Chen, Feida; Zhang, Yun; Chen, Da; Qiu, Yunlong


    Flexible flame-retardant composites were prepared using high-functional methyl vinyl silicone rubber matrix with B4C, hollow beads, and zinc borate (ZB) as filler materials. As filler content increased, the tensile strength, elongation, and tear strength of the composites initially increased and then decreased. The shore hardness of the composites increased with increasing filler content with a maximum value of 30 HA. The heat insulation properties of the composites with hollow beads were higher than that of the ordinary composites with the same filler mass fraction. When ZB content exceeded 12 wt%, the limit of oxygen index of the composites was higher than 27.1%. With Am-Be neutron as the test radiation source, the transmission of neutron for a 2 cm sample was only 47.8%. Powder surface modification improved the mechanical properties, thermal conductivity, flame retardancy, and neutron shielding performance of the composites, but did not affect shore hardness.

  8. Novel shielding materials for space and air travel. (United States)

    Vana, N; Hajek, M; Berger, T; Fugger, M; Hofmann, P


    The reduction of dose onboard spacecraft and aircraft by appropriate shielding measures plays an essential role in the future development of space exploration and air travel. The design of novel shielding strategies and materials may involve hydrogenous composites, as it is well known that liquid hydrogen is most effective in attenuating charged particle radiation. As precursor for a later flight experiment, the shielding properties of newly developed hydrogen-rich polymers and rare earth-doped high-density rubber were tested in various ground-based neutron and heavy ion fields and compared with aluminium and polyethylene as reference materials. Absorbed dose, average linear energy transfer and gamma-equivalent neutron absorbed dose were determined by means of LiF:Mg,Ti thermoluminescence dosemeters and CR-39 plastic nuclear track detectors. First results for samples of equal aerial density indicate that selected hydrogen-rich plastics and rare-earth-doped rubber may be more effective in attenuating cosmic rays by up to 10% compared with conventional aluminium shielding. The appropriate adaptation of shielding thicknesses may thus allow reducing the biologically relevant dose. Owing to the lower density of the plastic composites, mass savings shall result in a significant reduction of launch costs. The experiment was flown as part of the European Space Agency's Biopan-5 mission in May 2005.

  9. Improved Spacecraft Materials for Radiation Shielding (United States)

    Wilson, J. W.; Shinn, J. L.; Singleterry, R. C.; Tai, H.; Thibeault, S. A.; Simonsen, L. C.; Cucinotta, F. A.; Miller, J.


    In the execution of this proposal, we will first examine current and developing spacecraft materials and evaluate their ability to attenuate adverse biological mutational events in mammalian cell systems and reduce the rate of cancer induction in mice harderian glands as a measure of their protective qualities. The HZETRN code system will be used to generate a database on GCR attenuation in each material. If a third year of funding is granted, the most promising and mission-specific materials will be used to study the impact on mission cost for a typical Mars mission scenario as was planned in our original two year proposal at the original funding level. The most promising candidate materials will be further tested as to their transmission characteristics in Fe and Si ion beams to evaluate the accuracy of the HZETRN transmission factors. Materials deemed critical to mission success may also require testing as well as materials developed by industry for their radiation protective qualities (e.g., Physical Sciences Inc.) A study will be made of designing polymeric materials and composite materials with improved radiation shielding properties as well as the possible improvement of mission-specific materials.


    Cho, Yong In; Kim, Ja Mee; Kim, Jung Hoon


    To better understand the distribution of deposited energy of beta and gamma rays according to changes in shielding materials and thicknesses when radionuclides are used for therapeutic nuclear medicine, a simulation was conducted. The results showed that due to the physical characteristics of each therapeutic radionuclide, the thicknesses of shielding materials at which beta-ray shielding takes place varied. Additional analysis of the shielding of gamma ray was conducted for radionuclides that emit both beta and gamma rays simultaneously with results showing shielding effects proportional to the atomic number and density of the shielding materials. Also, analysis of bremsstrahlung emission after beta-ray interactions in the simulation revealed that the occurrence of bremsstrahlung was relatively lower than theoretically calculated and varied depending on different radionuclides.

  11. Neutron shielding material design based on Monte Carlo simulation%基于蒙特卡罗方法的中子屏蔽材料设计

    Institute of Scientific and Technical Information of China (English)

    陈飞达; 汤晓斌; 王鹏; 陈达


    基于蒙特卡罗粒子输运程序MCNP,设计了一种强度高、密度低、具有优异中子屏蔽性能的新型玻璃纤维/B4C/环氧树脂复合材料,模拟计算了镅-铍(Am-Be)中子源产生中子对该材料的透射率;研究了该材料的中子屏蔽性能与传统屏蔽材料的差异以及不同B4C质量分数对该材料的屏蔽性能影响;根据模拟结果分析了该材料对不同能区中子(慢中子、中能中子、快中子)具有的不同屏蔽性能.研究发现:B4C质量分数为10%的该种新型玻璃纤维/B4C/环氧树脂复合材料的中子屏蔽性能,尤其是慢中子屏蔽性能较传统的含硼聚乙烯和Al-B4C合金材料更为优异;但随着B4C质量分数的增大,屏蔽性能提升不明显.结果验证了蒙特卡罗方法用于中子屏蔽材料优化设计的可行性.%Based on the Monte Carlo particle transport program MCNP, a noveL glass fiber/B4 C/epoxy resin composite for neutron shielding with high strength and low density was developed. Its neutron transmissivity was calculated under the Am-Be neutron source condition to study the difference of neutron shielding performance between the glass fiber/B4 C/epoxy resin composite and traditional shielding materials. Furthermore, effects of B4 C mass fraction of the composite on the shielding performance for neutrons with different energy(slow neutron, intermediate neutron, fast neutron) were analyzed. The results show the composites with 10% B4C mass contents have more advantages on the neutron shielding performance , especially the slow neutron shielding performance in comparison with polyethylene/boron containing composites and Al-B4 C alloy. With the further increasing of the B4C contents, no remarkable increase is observed. Monte Carlo method is demonstrated feasible in optimization design of neutron shielding materials and the results provide a theoretical basis for design and preparation of a new neutron shielding composite.

  12. Gamma ray absorption of cylindrical fissile material with dual shields

    Institute of Scientific and Technical Information of China (English)

    WU Chen-Yan; TIAN Dong-Feng; CHENG Yi-Ying; HUANG Yong-Yi; LU Fu-Quan; YANG Fu-Jia


    This work analyzed the gamma ray attenuation effect from the self-absorption and shield attenuation perspectively. An exact mathematical equation was given for the geometric factor of the cylindrical fissile material with dual shields. In addition, several approximation approaches suitable for real situation were discussed, especially in the radial and axial directions of the cylinders, since the G-factors have simple forms. Then the space distribution patterns of the G-factor were analyzed based on numerical result and effective ways to solve the geometric information of the cylindrical fissile material, the radii and the heights, were deduced. This method was checked and verified by numerical calculation. Because of the efficiency of the method, it is ideal for application in real situations, such as nuclear safeguards, which demands speed of detection and accuracy of geometric analysis.

  13. Radiation fields from neutron generators shielded with different materials (United States)

    Chichester, D. L.; Blackburn, B. W.


    As a general guide for assessing radiological conditions around a DT neutron generator numerical modeling has been performed to assess neutron and photon dose profiles for a variety of shield materials ranging from 1 to 100 cm thick. In agreement with accepted radiation safety practices high-Z materials such as bismuth and lead have been found to be ineffective biological shield materials, owing in part to the existence of (n,2n) reaction channels available with 14.1 MeV DT neutrons, while low-Z materials serve as effective shields for these sources. Composite materials such as a mixture of polyethylene and bismuth, or regular concrete, are ideal shield materials for neutron generator radiation because of their ability to attenuate internally generated photon radiation resulting from neutron scattering and capture within the shields themselves.

  14. Tile concrete base materials as substitutes for lead shielding installations diagnostic X-ray; Losetas de materiales con base de hormigon como blindajes sustitutivos del plomo en instalaciones de rayos X de diagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Pombar Camean, M.; Pasin, J.; Fuestes-Vazquez, V.; Alonso, E.; Pereira, B.


    In this paper we study the damping characteristics in the energy range of medical diagnostic X-ray product X-RAD trade name manufactured by Construction Radiotherapy Techniques (CTRADC) consisting of different composition tile with concrete base, for its characterization as a substitute shielding material lead.

  15. Polybenzoxazine Materials for Radiation Shielding Project (United States)

    National Aeronautics and Space Administration — The proposed work will develop lightweight multifunctional composite materials based on high hydrogen content polybenzoxazine (PBZ) composites that provide excellent...

  16. Optimal Shielding for Minimum Materials Cost of Mass

    Energy Technology Data Exchange (ETDEWEB)

    Woolley, Robert D. [PPPL


    Material costs dominate some shielding design problems. This is certainly the case for manned nuclear power space applications for which shielding is essential and the cost of launching by rocket from earth is high. In such situations or in those where shielding volume or mass is constrained, it is important to optimize the design. Although trial and error synthesis methods may succeed a more systematic approach is warranted. Design automation may also potentially reduce engineering costs.

  17. Depleted uranium hexafluoride: The source material for advanced shielding systems

    Energy Technology Data Exchange (ETDEWEB)

    Quapp, W.J.; Lessing, P.A. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Cooley, C.R. [Department of Technology, Germantown, MD (United States)


    The U.S. Department of Energy (DOE) has a management challenge and financial liability problem in the form of 50,000 cylinders containing 555,000 metric tons of depleted uranium hexafluoride (UF{sub 6}) that are stored at the gaseous diffusion plants. DOE is evaluating several options for the disposition of this UF{sub 6}, including continued storage, disposal, and recycle into a product. Based on studies conducted to date, the most feasible recycle option for the depleted uranium is shielding in low-level waste, spent nuclear fuel, or vitrified high-level waste containers. Estimates for the cost of disposal, using existing technologies, range between $3.8 and $11.3 billion depending on factors such as the disposal site and the applicability of the Resource Conservation and Recovery Act (RCRA). Advanced technologies can reduce these costs, but UF{sub 6} disposal still represents large future costs. This paper describes an application for depleted uranium in which depleted uranium hexafluoride is converted into an oxide and then into a heavy aggregate. The heavy uranium aggregate is combined with conventional concrete materials to form an ultra high density concrete, DUCRETE, weighing more than 400 lb/ft{sup 3}. DUCRETE can be used as shielding in spent nuclear fuel/high-level waste casks at a cost comparable to the lower of the disposal cost estimates. Consequently, the case can be made that DUCRETE shielded casks are an alternative to disposal. In this case, a beneficial long term solution is attained for much less than the combined cost of independently providing shielded casks and disposing of the depleted uranium. Furthermore, if disposal is avoided, the political problems associated with selection of a disposal location are also avoided. Other studies have also shown cost benefits for low level waste shielded disposal containers.

  18. Shielding effectiveness of rectangular cavity made of a new shielding material and resonance suppression

    Institute of Scientific and Technical Information of China (English)


    New shielding material has become an alternative to traditional metal to shield boxes from electromagnetic interferences. This article introduces the theory of transmission line method to study the shield boxes made of a new sort of material, and then expands the fundamental formulas to deal with the cases of multiple holes and polarization with arbitrary angle. By means of genetic algorithms with the aid of a three dimensional simulation tool, the damping of electromagnetic resonances in enclosures is researched.The computation indicates that under resonant frequency, electromagnetic resonance results in low, even negative shielding coefficient; whereas, for the same areas, shielding effectiveness of a single hole is worse than that of multiple holes. Shielding coefficient varies when polarization angle increases, and the coupled field through the rectangular aperture with the long side parallel to the thin wire is much weaker than that with the long side vertical to the thin wire. By using the metallic-loss dielectric layer of optimized calculation on the internal surface of the cavity, the best result of resonance suppression has been realized with the same thickness of coating. Finally, according to the calculation result, suggestions for shielding are proposed.


    Directory of Open Access Journals (Sweden)

    BELOUSOVA Elena Sergeevna


    Full Text Available Modifications of shielding construction materials based on Portland cement with the addition of powder nanomaterial shungite were developed. Attenuation and re­flection of electromagnetic radiation for obtained materials were studied. Recommen­dations for using are given.

  20. Low Cost, Lightweight, Multifunctional Structural Shielding Materials Project (United States)

    National Aeronautics and Space Administration — This SBIR involves the development of a lightweight innovative material for use as structure and radiation shielding in one. APS has assembled a uniquely qualified...

  1. Application of Advanced Radiation Shielding Materials to Inflatable Structures Project (United States)

    National Aeronautics and Space Administration — This innovation is a weight-optimized, inflatable structure that incorporates radiation shielding materials into its construction, for use as a habitation module or...

  2. Composite Materials for Radiation Shielding During Deep Space Missions (United States)

    Grugel, R. N.; Watts, J.; Adams, J. H.; Rose, M. Franklin (Technical Monitor)


    Minimizing radiation exposure from the galactic cosmic ray (GCR) environment during deep space missions is essential to human health and sensitive instrument survivability. Given the fabrication constraints of space transportation vehicles protective shielding is, consequently, a complicated materials issue. These concerns are presented and considered in view of some novel composite materials being developed/suggested for GCR shielding applications. Advantages and disadvantages of the composites will be discussed as well as the need for coordinated testing/evaluation and modeling efforts.

  3. Verification of some building materials as gamma-ray shields. (United States)

    Mann, Kulwinder Singh; Singla, Jyoti; Kumar, Vipan; Sidhu, G S


    The shielding properties for gamma rays of a few low Z materials were investigated. The values of the mass attenuation coefficient, equivalent atomic number, effective atomic number, exposure buildup factor and energy absorption buildup factor were calculated and used to estimate the shielding effectiveness of the samples under investigation. It has been observed that the shielding effectiveness of a sample is directly related to its effective atomic number. The shielding character of any sample is a function of the incident photon energy. Good shielding behaviour has been verified in soil samples in the photon energy region of 0.015-0.30 MeV and of dolomite in 3-15 MeV. The results have been shown graphically with more useful conclusions.

  4. Homogeneous Dielectric Equivalents of Composite Material Shields

    Directory of Open Access Journals (Sweden)

    P. Tobola


    Full Text Available The paper deals with the methodology of replacing complicated parts of an airplane skin by simple homogeneous equivalents, which can exhibit similar shielding efficiency. On one hand, the airplane built from the virtual homogeneous equivalents can be analyzed with significantly reduced CPU-time demands and memory requirements. On the other hand, the equivalent model can estimate the internal fields satisfactory enough to evaluate the electromagnetic immunity of the airplane.

  5. Shielding effectiveness of original and modified building materials

    Directory of Open Access Journals (Sweden)

    T. Frenzel


    Full Text Available This contribution deals with the determination of the shielding effectiveness of building materials used for office, factory and government buildings. Besides the examination of standard materials, measurements were also performed on modified materials, e.g. ferro concrete with enhanced shielding effectiveness due to a changed mixture or structure of the reinforcement. The measurements of original and modified materials were carried out in a fully anechoic room (FAR according to IEEE 299-1997 from 80 MHz up to 10 GHz.

  6. A Gravitational Shielding Based on ZnS:Ag Phosphor


    De Aquino, Fran


    It was shown that there is a practical possibility of gravity control on electroluminescent (EL) materials (physics/0109060). We present here a type Gravitational Shielding based on an EL phosphor namely zinc sulfide doped with silver (ZnS:Ag) which can reduce the cost of the Gravitational Motor previously presented.

  7. Design of shielding-performance testing-device for reactors construction shielding-material based on 252Cf source%基于252Cf 源的反应堆结构屏蔽材料屏蔽性能测试装置设计

    Institute of Scientific and Technical Information of China (English)

    贺丹; 宋英明; 邹树梁; 徐守龙; 王晓冬; 朱志超; 谭桢干; 何志锋; 王新林


    Background: New material for the reactor shielding structure is one type of cast-steel impurity doping actinide elements have been adopted. The design parameters of the shielding performance testing device for the various parts of reactor can be obtained by Monte Carlo method. Purpose: This study aims to test the shielding performance of the shielding material of reactor. Methods: First of all, the testing device model was built based on a 252Cf neutron source. Three kinds of models (the thicknesses of the moderation layer, the protective layers of the neutron and gamma ray) are calculated respectively using the MCNP program for the shielding performance testing device. The GEANT4 program was used for the key moderation layer to verify the results obtained by the MCNP program. Results: Through the analysis of simulation results, we obtained optimal shielding materials and the thicknesses of material layer: moderator layer material is paraffin wax, which having a thickness of 8 cm, neutron shielding material is polyethylene, which having a thickness of 38 cm, and γ protective layer material is iron, which having a thickness of 11 cm. Conclusion: Simulation results show that the proposed shielding performance testing device can meet the requirements of neutron moderator, neutron protection and photon protection.%基于252Cf 中子源,构建了反应堆结构屏蔽材料屏蔽性能测试装置设计模型。采用 MCNP 程序建立了测试模型,并逐次模拟计算屏蔽性能测试装置慢化层、中子防护层、γ光子防护层厚度。对于关键的慢化层,采用 Geant4程序进一步验证 MCNP 程序的计算结果。通过分析模拟计算获得了最优屏蔽材料及厚度分别为:慢化层材料为石蜡,厚度为8 cm;中子防护层材料为聚乙烯,厚度为38 cm;γ防护层材料为铁,厚度为11 cm。模拟实验结果表明,所设计屏蔽性能测试装置能够满足中子慢化以及中子、光子防护的需要。

  8. A new lead-free radiation shielding material for radiotherapy. (United States)

    Yue, Kun; Luo, Wenyun; Dong, Xiaoqing; Wang, Chuanshan; Wu, Guohua; Jiang, Mawei; Zha, Yuanzi


    Lead has recently been recognised as a source of environmental pollution, including the lead used for radiation shielding in radiotherapy. The bremsstrahlung radiation caused by the interaction between the electron beam and lead may reduce the accuracy of radiotherapy. To avoid the use of lead, a new material composed of tungsten and hydrogenated styrene-butadiene-styrene copolymer is studied with the Monte Carlo (MC) method and experiment in this paper. The component of the material is chosen after simulation with the MC method and the practical measurement is taken to validate the shielding ability of the material. The result shows that the shielding ability of the new material is good enough to fulfill the requirement for application in radiotherapy. Compared with lead alloy, the present new material is so flexible that can be easily customized into arbitrary shapes. Moreover, the material is environmentally friendly and can be recycled conveniently. Therefore, the material can be used as an effective lead substitute for shielding against electron beams in radiotherapy.

  9. Optimizing non-Pb radiation shielding materials using bilayers

    Energy Technology Data Exchange (ETDEWEB)

    McCaffrey, J. P.; Mainegra-Hing, E.; Shen, H. [Institute for National Measurement Standards, National Research Council of Canada, Building M-35, 1200 Montreal Road, Ottawa K1A 0R6 (Canada)


    Purpose: The objective of this study was to demonstrate that the weight of non-Pb radiation shielding materials can be minimized by structuring the material as a bilayer composed of different metal-powder-embedded elastomer layers. Methods: Measurements and Monte Carlo (MC) calculations were performed to study the attenuation properties of several non-Pb metal bilayers over the x-ray energy range 30-150 keV. Metals for the layers were chosen on the basis of low cost, nontoxicity, and complementary photoelectric absorption characteristics. The EGSnrc user code cavity.cpp was used to calculate the resultant x-ray fluence spectra after attenuation by these metal layers. Air kerma attenuation was measured using commercially manufactured metal/elastomer test layers. These layers were irradiated using the primary standard calibration beams at the Institute for National Measurement Standards in Ottawa, Canada utilizing the six x-ray beam qualities recommended in the German Standard DIN 6857. Both the measurements and the calculations were designed to approximate surface irradiation as well as penetrating radiation at 10 mm depth in soft tissue. The MC modeling point and the position of the measurement detector for surface irradiation were both directly against the downstream face of the attenuating material, as recommended in DIN 6857. Results: The low-Z upstream/high-Z downstream ordering of the metal bilayers provided substantially more attenuation than the reverse order. Optimal percentages of each metal in each bilayer were determined for each x-ray radiation beam quality. Conclusions: Depending on the x-ray quality, appropriate choices of two complementary metal-embedded elastomer layers can decrease the weight of radiation shielding garments by up to 25% compared to Pb-based elastomer garments while providing equivalent attenuation.

  10. Radiation Exposure Effects and Shielding Analysis of Carbon Nanotube Materials (United States)

    Wilkins, Richard; Armendariz, Lupita (Technical Monitor)


    Carbon nanotube materials promise to be the basis for a variety of emerging technologies with aerospace applications. Potential applications to human space flight include spacecraft shielding, hydrogen storage, structures and fixtures and nano-electronics. Appropriate risk analysis on the properties of nanotube materials is essential for future mission safety. Along with other environmental hazards, materials used in space flight encounter a hostile radiation environment for all mission profiles, from low earth orbit to interplanetary space.

  11. Electromagnetic shielding. Citations from the NTIS data base (United States)

    Reed, W. E.


    The bibliography presents research on electromagnetic shielding of electronic and electrical equipment personnel, and ordnance. The shielding effectiveness of materials and structures is covered. Nuclear electromagnetic pulse shielding is included. This updated bibliography contains 301 abstracts, 19 of which are new entries to the previous edition.

  12. Establishment of Testing Device for Shielding Performance of X and Gamma Ray Radiation Protection Materials

    Institute of Scientific and Technical Information of China (English)

    SONG; Ming-zhe; WEI; Ke-xin; HOU; Jin-bing; WANG; Hong-yu; GAO; Fei; NI; Ning


    X and gamma ray radiation protective material shielding performance testing device was built based on the international standard IEC61331.1-2014.The device can be used to test attenuation ratio,attenuation equivalent and lead equivalent of radiation protective material in"narrow beam condition","broad beam condition"and"inverse

  13. Flexible neutron shielding composite material of EPDM rubber with boron trioxide: Mechanical, thermal investigations and neutron shielding tests (United States)

    Özdemir, T.; Güngör, A.; Reyhancan, İ. A.


    In this study, EPDM and boron trioxide composite was produced and mechanical, thermal and neutron shielding tests were performed. EPDM rubber (Ethylene Propylene Diene Monomer) having a considerably high hydrogen content is an effective neutron shielding material. On the other hand, the materials containing boron components have effective thermal neutron absorption crossection. The composite of EPDM and boron trioxide would be an effective solution for both respects of flexibility and effectiveness for developing a neutron shielding material. Flexible nature of EPDM would be a great asset for the shielding purpose in case of intervention action to a radiation accident. The theoretical calculations and experimental neutron absorption tests have shown that the results were in parallel and an effective neutron shielding has been achieved with the use of the developed composite material.


    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, K; Kerry Dunn, K; Joseph Murphy, J


    Inspection of United States-Department of Energy (US-DOE) model 9975 nuclear materials shipping package revealed corrosion of the lead shielding that was induced by off-gas constituents from organic components in the package. Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of these organic materials. The results showed that the room temperature vulcanizing (RTV) sealant was the most corrosive organic species used in the construction of the packaging, followed by polyvinyl acetate (PVAc) glue. Fiberboard material, also used in the construction of the packaging induced corrosion to a much lesser extent than the PVAc glue and RTV sealant, and only in the presence of condensed water. The results indicated faster corrosion at temperatures higher than ambient and with condensed water. In light of these corrosion mechanisms, the lead shielding was sheathed in a stainless steel liner to mitigate against corrosion.

  15. Optimal per cent by weight of elements in diagnostic quality radiation shielding materials. (United States)

    Ashayer, Sahar; Askari, Mansur; Afarideh, Hossein


    By increasing the usage of radiation in all aspects of lives, the human body is becoming more exposed to ionising radiation. The purpose of this study is to find the optimal radiation shielding materials to protect humans from the radiation hazards of radiation. Some elements and compounds such as Ag, Bi, Pb, W, BaSO(4) were chosen on the basis of their attenuation coefficients and other characteristics to produce optimised radiation shielding compounds. Multi-objective non-dominated sorting genetic algorithm-II was used to optimise the weight fraction of the elements in compounds based on the dose equivalent rate, shield weight and cost. Consequently, sets of suitable compounds were obtained depending on various applications for energy 0.06 and 0.15 MeV. In addition, optimised lead free compounds were obtained. The results presented in a series of graphs should enable radiation shield designers to choose an appropriate combination according to their requirements.

  16. Reliability-Based Electronics Shielding Design Tools (United States)

    Wilson, J. W.; O'Neill, P. J.; Zang, T. A.; Pandolf, J. E.; Tripathi, R. K.; Koontz, Steven L.; Boeder, P.; Reddell, B.; Pankop, C.


    Shielding design on large human-rated systems allows minimization of radiation impact on electronic systems. Shielding design tools require adequate methods for evaluation of design layouts, guiding qualification testing, and adequate follow-up on final design evaluation.

  17. Novel light-weight materials for shielding gamma ray (United States)

    Chen, Shuo; Bourham, Mohamed; Rabiei, Afsaneh


    A comparison of gamma ray attenuation effectiveness of bulk aluminum, close-cell composite metal foams and open-cell aluminum foam infiltrated with variety of second phase materials were investigated and reported in this study. Mass attenuation coefficients for six sets of samples with three different areal densities of 2, 5 and 10 g/cm2 were determined at photon energies of 0.060, 0.662, 1.173, and 1.332 MeV. Theoretical values were calculated using XCOM software package. A complete agreement was observed between experimental and theoretical results. It is observed that close-cell composite metal foams exhibit a better shielding capability compared to open-cell Al foam with fillers. It is also observed that close-cell composite metal foams offer superior shielding effectiveness compared to bulk aluminum for energies below 0.662 MeV, the mass attenuation coefficients of steel-steel composite metal foam and Al-steel composite metal foam were measured 400 and 300% higher than that of aluminum A356. This study indicates the potential of utilizing the light-weight composite metal foams as shielding material replacing current heavy materials used for attenuation of low energy gamma ray with additional advantages such as high energy absorption and excellent heat rejection capabilities.

  18. Application of nano material for shielding power-frequency electromagnetic field (United States)

    Li, Hualiang; Li, Li; Liu, Jiawen


    Only limited data are available on shielding electromagnetic field exposure in professional work. In our paper, we studied the electromagnetic field intensity in 500 kV substations, and explored influence of nanomaterial in high voltage laboratory simulation. Moreover, the results of nano-fabrics material for shielding power frequency electromagnetic field indicated that, both shielding fabrics can almost completely shield the electric field, but have weak shielding effectiveness against magnetic field.

  19. Shielding design studies for a neutron irradiator system based on a 252Cf source. (United States)

    da Silva, A X; Crispim, V R


    This study aims to investigate a shielding design against neutrons and gamma rays from a source of 252Cf, using Monte Carlo simulation. The shielding materials studied were borated polyethylene, borated-lead polyethylene and stainless steel. The Monte Carlo code MCNP4B was used to design shielding for 252Cf based neutron irradiator systems. By normalising the dose equivalent rate values presented to the neutron production rate of the source, the resulting calculations are independent of the intensity of the actual 252Cf source. The results show that the total dose equivalent rates were reduced significantly by the shielding system optimisation.

  20. Reflector and Shield Material Properties for Project Prometheus

    Energy Technology Data Exchange (ETDEWEB)

    J. Nash


    This letter provides updated reflector and shield preliminary material property information to support reactor design efforts. The information provided herein supersedes the applicable portions of Revision 1 to the Space Power Program Preliminary Reactor Design Basis (Reference (a)). This letter partially answers the request in Reference (b) to provide unirradiated and irradiated material properties for beryllium, beryllium oxide, isotopically enriched boron carbide ({sup 11}B{sub 4}C) and lithium hydride. With the exception of {sup 11}B{sub 4}C, the information is provided in Attachments 1 and 2. At the time of issuance of this document, {sup 11}B{sub 4}C had not been studied.

  1. Radiation attenuation by lead and nonlead materials used in radiation shielding garments. (United States)

    McCaffrey, J P; Shen, H; Downton, B; Mainegra-Hing, E


    The attenuating properties of several types of lead (Pb)-based and non-Pb radiation shielding materials were studied and a correlation was made of radiation attenuation, materials properties, calculated spectra and ambient dose equivalent. Utilizing the well-characterized x-ray and gamma ray beams at the National Research Council of Canada, air kerma measurements were used to compare a variety of commercial and pre-commercial radiation shielding materials over mean energy ranges from 39 to 205 keV. The EGSnrc Monte Carlo user code cavity. cpp was extended to provide computed spectra for a variety of elements that have been used as a replacement for Pb in radiation shielding garments. Computed air kerma values were compared with experimental values and with the SRS-30 catalogue of diagnostic spectra available through the Institute of Physics and Engineering in Medicine Report 78. In addition to garment materials, measurements also included pure Pb sheets, allowing direct comparisons to the common industry standards of 0.25 and 0.5 mm "lead equivalent." The parameter "lead equivalent" is misleading, since photon attenuation properties for all materials (including Pb) vary significantly over the energy spectrum, with the largest variations occurring in the diagnostic imaging range. Furthermore, air kerma measurements are typically made to determine attenuation properties without reference to the measures of biological damage such as ambient dose equivalent, which also vary significantly with air kerma over the diagnostic imaging energy range. A single material or combination cannot provide optimum shielding for all energy ranges. However, appropriate choice of materials for a particular energy range can offer significantly improved shielding per unit mass over traditional Pb-based materials.

  2. A novel shielding material prepared from solid waste containing lead for gamma ray (United States)

    Erdem, Mehmet; Baykara, Oktay; Doğru, Mahmut; Kuluöztürk, Fatih


    Human beings are continuously exposed to cosmogenic radiation and its products in the atmosphere from naturally occurring radioactive materials (NORM) within Earth, their bodies, houses and foods. Especially, for the radiation protection environments where high ionizing radiation levels appear should be shielded. Generally, different materials are used for the radiation shielding in different areas and for different situations. In this study, a novel shielding material produced by a metallurgical solid waste containing lead was analyzed as shielding material for gamma radiation. The photon total mass attenuation coefficients ( μ/ ρ) were measured and calculated using WinXCom computer code for the novel shielding material, concrete and lead. Theoretical and experimental values of total mass attenuation coefficient of the each studied sample were compared. Consequently, a new shielding material prepared from the solid waste containing lead could be preferred for buildings as shielding materials against gamma radiation.

  3. Elrotherm shielding systems. New pioneering material composites; Elrotherm-Abschirmsysteme. Neue Zukunftsweisende Materialkompositionen

    Energy Technology Data Exchange (ETDEWEB)

    Zika-Beyerlein, B. [ElringKlinger (Germany). Geschaeftsbereich Abschirmtechnik


    Tightly packed engine compartments put special demands on thermal and acoustic shielding systems. With new material composites allowing for particularly thin-walled and light shielding parts, ElringKlinger is well equipped for the future. (orig.)

  4. Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study Project (United States)

    National Aeronautics and Space Administration — The objectives of the proposed research are to develop a space radiation shielding material system that has high efficacy for shielding radiation and also has high...

  5. Paddle-based rotating-shield brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yunlong; Xu, Weiyu [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 (United States); Flynn, Ryan T.; Kim, Yusung; Bhatia, Sudershan K.; Buatti, John M. [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Dadkhah, Hossein [Department of Biomedical Engineering, University of Iowa, 1402 Seamans Center, Iowa City, Iowa 52242 (United States); Wu, Xiaodong, E-mail: [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 and Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)


    Purpose: The authors present a novel paddle-based rotating-shield brachytherapy (P-RSBT) method, whose radiation-attenuating shields are formed with a multileaf collimator (MLC), consisting of retractable paddles, to achieve intensity modulation in high-dose-rate brachytherapy. Methods: Five cervical cancer patients using an intrauterine tandem applicator were considered to assess the potential benefit of the P-RSBT method. The P-RSBT source used was a 50 kV electronic brachytherapy source (Xoft Axxent™). The paddles can be retracted independently to form multiple emission windows around the source for radiation delivery. The MLC was assumed to be rotatable. P-RSBT treatment plans were generated using the asymmetric dose–volume optimization with smoothness control method [Liu et al., Med. Phys. 41(11), 111709 (11pp.) (2014)] with a delivery time constraint, different paddle sizes, and different rotation strides. The number of treatment fractions (fx) was assumed to be five. As brachytherapy is delivered as a boost for cervical cancer, the dose distribution for each case includes the dose from external beam radiotherapy as well, which is 45 Gy in 25 fx. The high-risk clinical target volume (HR-CTV) doses were escalated until the minimum dose to the hottest 2 cm{sup 3} (D{sub 2cm{sup 3}}) of either the rectum, sigmoid colon, or bladder reached their tolerance doses of 75, 75, and 90 Gy{sub 3}, respectively, expressed as equivalent doses in 2 Gy fractions (EQD2 with α/β = 3 Gy). Results: P-RSBT outperformed the two other RSBT delivery techniques, single-shield RSBT (S-RSBT) and dynamic-shield RSBT (D-RSBT), with a properly selected paddle size. If the paddle size was angled at 60°, the average D{sub 90} increases for the delivery plans by P-RSBT on the five cases, compared to S-RSBT, were 2.2, 8.3, 12.6, 11.9, and 9.1 Gy{sub 10}, respectively, with delivery times of 10, 15, 20, 25, and 30 min/fx. The increases in HR-CTV D{sub 90}, compared to D-RSBT, were 16

  6. Application of solid waste containing lead for gamma ray shielding material




    Abstract. The basic strategies to decrease solid waste disposal problems have focused on the reduction of waste production and recovery of usable materials using waste and making raw materials. Generally, various materials have been used for radiation shielding in different areas and situations. In this study, a novel shielding material produced by a metallurgical solid waste containing lead has been analyzed in order to make a shielding material against gamma radiation. The photon total mass...


    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, K; Kerry Dunn, K


    Inspection of United States-Department of Energy (US-DOE) model 9975 nuclear materials shipping package revealed corrosion of the lead shielding induced by off-gas constituents from organic components in the package. Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of these organic materials. The results showed that the room temperature vulcanizing (RTV) sealant was the most corrosive organic species followed by the polyvinyl acetate (PVAc) glue. The fiberboard material induced corrosion to a much lesser extent than the PVAc glue and RTV, and only in the presence of condensed water. The results indicated faster corrosion at temperatures higher than ambient and with condensed water as expected. A corrosion rate of 0.05 mm/year measured for coupons exposed to the most aggressive conditions was recommended as a conservative estimate for use in package performance calculations.

  8. Materials for Shielding Astronauts from the Hazards of Space Radiations (United States)

    Wilson, J. W.; Cucinotta, F. A.; Miller, J.; Shinn, J. L.; Thibeault, S. A.; Singleterry, R. C.; Simonsen, L. C.; Kim, M. H.


    One major obstacle to human space exploration is the possible limitations imposed by the adverse effects of long-term exposure to the space environment. Even before human spaceflight began, the potentially brief exposure of astronauts to the very intense random solar energetic particle (SEP) events was of great concern. A new challenge appears in deep space exploration from exposure to the low-intensity heavy-ion flux of the galactic cosmic rays (GCR) since the missions are of long duration and the accumulated exposures can be high. Because cancer induction rates increase behind low to rather large thickness of aluminum shielding according to available biological data on mammalian exposures to GCR like ions, the shield requirements for a Mars mission are prohibitively expensive in terms of mission launch costs. Preliminary studies indicate that materials with high hydrogen content and low atomic number constituents are most efficient in protecting the astronauts. This occurs for two reasons: the hydrogen is efficient in breaking up the heavy GCR ions into smaller less damaging fragments and the light constituents produce few secondary radiations (especially few biologically damaging neutrons). An overview of the materials related issues and their impact on human space exploration will be given.

  9. Detection of explosives, shielded nuclear materials and other hazardous substances in cargo containers (United States)

    Kuznetsov, Andrey; Evsenin, Alexey; Vakhtin, Dmitry; Gorshkov, Igor; Osetrov, Oleg; Kalinin, Valery


    Nanosecond Neutron Analysis / Associated Particles Technique (NNA/APT) has been used to create devices for detection of explosives, radioactive and heavily shielded nuclear materials in cargo containers. Explosives and other hazardous materials are detected by analyzing secondary high-energy gamma-rays form reactions of fast neutrons with the materials inside the container. Depending on the dimensions of the inspected containers, the detecting system consists of one or several detection modules, each of which contains a small neutron generator with built-in position sensitive detector of associated alpha-particles and several scintillator-based gamma-ray detectors. The same gamma-ray detectors are used to detect unshielded radioactive and nuclear materials. Array of several detectors of fast neutrons is used to detect neutrons from spontaneous and induced fission of nuclear materials. These neutrons can penetrate thick layers of lead shielding, which can be used to conceal gamma-radioactivity from nuclear materials. Coincidence and timing analysis allows one to discriminate between fission neutrons and scattered probing neutrons. Mathematical modeling by MCNP5 code was used to estimate the sensitivity of the device and its optimal configuration. Capability of the device to detect 1 kg of explosive imitator inside container filled with suitcases and other baggage items has been confirmed experimentally. First experiments with heavily shielded nuclear materials have been carried out.

  10. Materials for Low-Energy Neutron Radiation Shielding (United States)

    Singleterry, Robert C., Jr.; Thibeault, Sheila A.


    Various candidate aircraft and spacecraft materials were analyzed and compared in a low-energy neutron environment using the Monte Carlo N-Particle (MCNP) transport code with an energy range up to 20 MeV. Some candidate materials have been tested in particle beams, and others seemed reasonable to analyze in this manner before deciding to test them. The two metal alloys analyzed are actual materials being designed into or used in aircraft and spacecraft today. This analysis shows that hydrogen-bearing materials have the best shielding characteristics over the metal alloys. It also shows that neutrons above 1 MeV are reflected out of the face of the slab better by larger quantities of carbon in the material. If a low-energy absorber is added to the material, fewer neutrons are transmitted through the material. Future analyses should focus on combinations of scatterers and absorbers to optimize these reaction channels and on the higher energy neutron component (above 50 MeV).

  11. Development of Multifunctional Radiation Shielding Materials for Long Duration Human Exploration Beyond the Low Earth Orbit (United States)

    Sen, S.; Bhattacharya, M.; Schofield, E.; Carranza, S.; O'Dell, S.


    One of the major challenges for long duration human exploration beyond the low Earth orbit and sustained human presence on planetary surfaces would be development of materials that would help minimize the radiation exposure to crew and equipment from the interplanetary radiation environment, This radiation environment consists primarily of a continuous flux of galactic cosmic rays (GCR) and transient but intense fluxes of solar energetic particles (SEP). The potential for biological damage by the relatively low percentage of high-energy heavy-ions in the GCR spectrum far outweigh that due to lighter particles because of their ionizing-power and the quality of the resulting biological damage. Although the SEP spectrum does not contain heavy ions and their energy range is much lower than that for GCRs, they however pose serious risks to astronaut health particularly in the event of a bad solar storm The primary purpose of this paper is to discuss our recent efforts in development and evaluation of materials for minimizing the hazards from the interplanetary radiation environment. Traditionally, addition of shielding materials to spacecrafts has invariably resulted in paying a penalty in terms of additional weight. It would therefore be of great benefit if materials could be developed not only with superior shielding effectiveness but also sufficient structural integrity. Such a multifunctional material could then be considered as an integral part of spacecraft structures. Any proposed radiation shielding material for use in outer space should be composed of nuclei that maximize the likelihood of projectile fragmentation while producing the minimum number of target fragments. A modeling based approach will be presented to show that composite materials using hydrogen-rich epoxy matrices reinforced with polyethylene fibers and/or fabrics could effectively meet this requirement. This paper will discuss the fabrication of such a material for a crewed vehicle. Ln addition

  12. Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study. Phase I (United States)

    Thibeault, Sheila A.; Fay, Catharine C.; Lowther, Sharon E.; Earle, Kevin D.; Sauti, Godfrey; Kang, Jin Ho; Park, Cheol; McMullen, Amelia M.


    than possible with hydrogen storage; however, a systematic experimental hydrogenation study has not been reported. A combination of the two approaches may be explored to provide yet higher hydrogen content. The hydrogen containing BNNT produced in our study will be characterized for hydrogen content and thermal stability in simulated space service environments. These new materials systems will be tested for their radiation shielding effectiveness against high energy protons and high energy heavy ions at the HIMAC facility in Japan, or a comparable facility. These high energy particles simulate exposure to SEP and GCR environments. They will also be tested in the LaRC Neutron Exposure Laboratory for their neutron shielding effectiveness, an attribute that determines their capability to shield against the secondary neutrons found inside structures and on lunar and planetary surfaces. The potential significance is to produce a radiation protection enabling technology for future exploration missions. Crew on deep space human exploration missions greater than approximately 90 days cannot remain below current crew Permissible Exposure Limits without shielding and/or biological countermeasures. The intent of this research is to bring the Agency closer to extending space missions beyond the 90-day limit, with 1 year as a long-term goal. We are advocating a systems solution with a structural materials component. Our intent is to develop the best materials system for that materials component. In this Phase I study, we have shown, computationally, that hydrogen containing BNNT is effective for shielding against GCR, SEP, and neutrons over a wide range of energies. This is why we are focusing on hydrogen containing BNNT as an innovative advanced concept. In our future work, we plan to demonstrate, experimentally, that hydrogen, boron, and nitrogen based materials can provide mechanically strong, thermally stable, structural materials with effective radiation shielding against GCR

  13. Design, fabrication, and properties of a continuous carbon-fiber reinforced Sm{sub 2}O{sub 3}/polyimide gamma ray/neutron shielding material

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Tang, Xiaobin, E-mail: [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering, Nanjing 210016 (China); Chai, Hao [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Chen, Da [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering, Nanjing 210016 (China); Qiu, Yunlong [ZhongXing Energy Equipment Co., Ltd, Haimen, Nantong 226100 (China)


    Highlights: • Sm{sub 2}O{sub 3} is used for neutron absorber instead of B{sub 4}C, and Sm{sub 2}O{sub 3} has a good photon-shielding effect. • Carbon-fiber cloth and polyimide were used to enhance shielding materials’ mechanical behavior and thermal behavior. • Both Monte Carlo method and shielding test were used to evaluate shielding performance of the novel shielding material. - Abstract: The design and fabrication of shielding materials with good heat-resistance and mechanical properties is a major problem in the radiation shielding field. In this paper, based on gamma ray and neutron shielding theory, a continuous carbon-fiber reinforced Sm{sub 2}O{sub 3}/polyimide gamma ray/neutron shielding material was fabricated by hot-pressing method. The material's application behavior was subsequently evaluated using neutron shielding, photon shielding, mechanical tensile, and thermogravimetric analysis–differential scanning calorimetry tests. The results show that the tensile strength of the novel shielding material exceeds 200 MPa, which makes it of similar strength to aluminum alloy. The material does not undergo crosslinking and decomposition reactions at 300 °C and it can be used in such environments for long periods of time. The continuous carbon-fiber reinforced Sm{sub 2}O{sub 3}/polyimide material has a good shielding performance with respect to gamma rays and neutrons. The material thus has good prospects for use in fusion reactor system and nuclear waste disposal applications.

  14. The Exploration Atmospheres Working Group's Report on Space Radiation Shielding Materials (United States)

    Barghouty, A. F.; Thibeault, S. A.


    This part of Exploration Atmospheres Working Group analyses focuses on the potential use of nonmetallic composites as the interior walls and structural elements exposed to the atmosphere of the spacecraft or habitat. The primary drive to consider nonmetallic, polymer-based composites as an alternative to aluminum structure is due to their superior radiation shielding properties. But as is shown in this analysis, these composites can also be made to combine superior mechanical properties with superior shielding properties. In addition, these composites can be made safe; i.e., with regard to flammability and toxicity, as well as "smart"; i.e., embedded with sensors for the continuous monitoring of material health and conditions. The analysis main conclusions are that (1) smart polymer-based composites are an enabling technology for safe and reliable exploration missions, and (2) an adaptive, synergetic systems approach is required to meet the missions requirements from structure, properties, and processes to crew health and protection for exploration missions.

  15. Materials development for ITER shielding and test blanket in China

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.M., E-mail: [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China); Wu, J.H.; Liu, X.; Wang, P.H. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China); Wang, Z.H.; Li, Z.N. [Ningxia Orient Non-ferrous Metals Group Co. Ltd., P.O. Box 105, Shizuishan (China); Wang, X.S.; Zhang, P.C. [China Academy of Engineering Physics, P.O. Box 919-71, Mianyang 621900 (China); Zhang, N.M.; Fu, H.Y.; Liu, D.H. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China)


    China is a member of the ITER program and is developing her own materials for its shielding and test blanket modules. The materials include vacuum-hot-pressing (VHP) Be, CuCrZr alloy, 316L(N) and China low activation ferritic/martensitic (CLF-1) steels. Joining technologies including Be/Cu hot isostatic pressing (HIP) and electron beam (EB) weldability of 316L(N) were investigated. Chinese VHP-Be showed good properties, with BeO content and ductility that satisfy the ITER requirements. Be/Cu mock-ups were fabricated for Be qualification tests at simulated ITER vertical displacement event (VDE) and heat flux cycling conditions. Fine microstructure and good mechanical strength of the CuCrZr alloy were achieved by a pre-forging treatment, while the weldability of 316L(N) by EB was demonstrated for welding depths varying from 5 to 80 mm. Fine microstructure, high strength, and good ductility were achieved in CLF-1 steel by an optimized normalizing, tempering and aging procedure.

  16. Monte Carlo based radial shield design of typical PWR reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gul, Anas; Khan, Rustam; Qureshi, M. Ayub; Azeem, Muhammad Waqar; Raza, S.A. [Pakistan Institute of Engineering and Applied Sciences, Islamabad (Pakistan). Dept. of Nuclear Engineering; Stummer, Thomas [Technische Univ. Wien (Austria). Atominst.


    Neutron and gamma flux and dose equivalent rate distribution are analysed in radial and shields of a typical PWR type reactor based on the Monte Carlo radiation transport computer code MCNP5. The ENDF/B-VI continuous energy cross-section library has been employed for the criticality and shielding analysis. The computed results are in good agreement with the reference results (maximum difference is less than 56 %). It implies that MCNP5 a good tool for accurate prediction of neutron and gamma flux and dose rates in radial shield around the core of PWR type reactors.

  17. Research of glass fibre used in the electromagnetic wave shielding and absorption composite material (United States)

    Xu, M.; Jia, F.; Bao, H. Q.; Cui, K.; Zhang, F.


    Electromagnetic shielding and absorption composite material plays an important role in the defence and economic field. Comparing with other filler, Glass fibre and its processed product—metal-coated glass fibre can greatly reduce the material's weight and costs, while it still remains the high strength and the electromagnetic shielding effectiveness. In this paper, the electromagnetic absorption mechanism and the reflection mechanism have been investigated as a whole, and the shielding effectiveness of the double-layer glass fibre composite material is mainly focused. The relationship between the shielding effectiveness and the filled glass fibre as well as its metal-coated product's parameters has also been studied. From the subsequent coaxial flange and anechoic chamber analysis, it can be confirmed that the peak electromagnetic shielding effectiveness of this double-layer material can reach -78dB while the bandwidth is from 2GHz to 18GHz.

  18. Characterizing and Manufacturing Multifunctional Radiation Shielding Materials Project (United States)

    National Aeronautics and Space Administration — This project addresses two vital problems for long-term space travel activities: radiation shielding and hydrogen storage for power and propulsion. While both...

  19. Space Vehicle Heat Shield Having Edgewise Strips of Ablative Material (United States)

    Blosser, Max L. (Inventor); Poteet, Carl C. (Inventor); Bouslog, Stan A. (Inventor)


    A heat shield for a space vehicle comprises a plurality of phenolic impregnated carbon ablator (PICA) blocks secured to a surface of the space vehicle and arranged in a pattern with gaps therebetween. The heat shield further comprises a plurality of PICA strips disposed in the gaps between the PICA blocks. The PICA strips are mounted edgewise, such that the structural orientation of the PICA strips is substantially perpendicular to the structural orientation of the PICA blocks.

  20. Neutron and gamma radiation shielding material, structure, and process of making structure

    Energy Technology Data Exchange (ETDEWEB)

    Hondorp, H.L.


    The present invention is directed to a novel neutron and gamma radiation shielding material consisting of 95 to 97% by weight SiO/sub 2/ and 5 to 3% by weight sodium silicate. In addition, the method of using this composition to provide a continuous neutron and gamma radiation shielding structure is disclosed.

  1. Boron cage compound materials and composites for shielding and absorbing neutrons (United States)

    Bowen, III, Daniel E; Eastwood, Eric A


    Boron cage compound-containing materials for shielding and absorbing neutrons. The materials include BCC-containing composites and compounds. BCC-containing compounds comprise a host polymer and a BCC attached thereto. BCC-containing composites comprise a mixture of a polymer matrix and a BCC filler. The BCC-containing materials can be used to form numerous articles of manufacture for shielding and absorbing neutrons.

  2. Barium-borate-flyash glasses: As radiation shielding materials (United States)

    Singh, Sukhpal; Kumar, Ashok; Singh, Devinder; Thind, Kulwant Singh; Mudahar, Gurmel S.


    The attenuation coefficients of barium-borate-flyash glasses have been measured for γ-ray photon energies of 356, 662, 1173 and 1332 keV using narrow beam transmission geometry. The photon beam was highly collimated and overall scatter acceptance angle was less than 3°. Our results have an uncertainty of less than 3%. These coefficients were then used to obtain the values of mean free path (mfp), effective atomic number and electron density. Good agreements have been observed between experimental and theoretical values of these parameters. From the studies of the obtained results it is reported here that from the shielding point of view the barium-borate-flyash glasses are better shields to γ-radiations in comparison to the standard radiation shielding concretes and also to the ordinary barium-borate glasses.

  3. Monte Carlo simulation of photon buildup factors for shielding materials in diagnostic x-ray facilities

    Energy Technology Data Exchange (ETDEWEB)

    Kharrati, Hedi; Agrebi, Amel; Karoui, Mohamed Karim [Ecole Superieure des Sciences et Techniques de la Sante de Monastir, Avenue Avicenne, 5000 Monastir (Tunisia); Faculte des Sciences de Monastir, 5000 Monastir (Tunisia)


    Purpose: A simulation of buildup factors for ordinary concrete, steel, lead, plate glass, lead glass, and gypsum wallboard in broad beam geometry for photons energies from 10 keV to 150 keV at 5 keV intervals is presented. Methods: Monte Carlo N-particle radiation transport computer code has been used to determine the buildup factors for the studied shielding materials. Results: An example concretizing the use of the obtained buildup factors data in computing the broad beam transmission for tube potentials at 70, 100, 120, and 140 kVp is given. The half value layer, the tenth value layer, and the equilibrium tenth value layer are calculated from the broad beam transmission for these tube potentials. Conclusions: The obtained values compared with those calculated from the published data show the ability of these data to predict shielding transmission curves. Therefore, the buildup factors data can be combined with primary, scatter, and leakage x-ray spectra to provide a computationally based solution to broad beam transmission for barriers in shielding x-ray facilities.

  4. Space Station Validation of Advanced Radiation-Shielding Polymeric Materials Project (United States)

    National Aeronautics and Space Administration — In Subtopic X11.01, NASA has identified the need to develop advanced radiation-shielding materials and systems to protect humans from the hazards of space radiation...

  5. Space Station Validation of Advanced Radiation-Shielding Polymeric Materials Project (United States)

    National Aeronautics and Space Administration — In Subtopic X11-01, NASA has identified the need to develop advanced radiation-shielding materials and systems to protect humans from the hazards of space radiation...

  6. Monte Carlo calculations of the energy deposited in biological samples and shielding materials (United States)

    Akar Tarim, U.; Gurler, O.; Ozmutlu, E. N.; Yalcin, S.


    The energy deposited by gamma radiation from the Cs-137 isotope into body tissues (bone and muscle), tissue-like medium (water), and radiation shielding materials (concrete, lead, and water), which is of interest for radiation dosimetry, was obtained using a simple Monte Carlo algorithm. The algorithm also provides a realistic picture of the distribution of backscattered photons from the target and the distribution of photons scattered forward after several scatterings in the scatterer, which is useful in studying radiation shielding. The presented method in this work constitutes an attempt to evaluate the amount of energy absorbed by body tissues and shielding materials.

  7. Radiation Protection of New Lightweight Electromagnetic Interference Shielding Materials Determined (United States)


    Weight savings as high as 80 percent could be achieved by simply switching from aluminum electromagnetic interference (EMI) shielding covers for spacecraft power systems to EMI covers made from intercalated graphite fiber composites. Because EMI covers typically make up about one-fifth of the power system mass, this change would decrease the mass of a spacecraft power system by more than 15 percent. Intercalated graphite fibers are made by diffusing guest atoms or molecules, such as bromine, between the carbon planes of the graphite fibers. The resulting bromine-intercalated fibers have mechanical and thermal properties nearly identical to pristine graphite fibers, but their resistivity is lower by a factor of 5, giving them better electrical conductivity than stainless steel and making these composites suitable for EMI shielding.

  8. Electromagnetic shielding effectiveness and mechanical properties of graphite-based polymeric films (United States)

    Kenanakis, G.; Vasilopoulos, K. C.; Viskadourakis, Z.; Barkoula, N.-M.; Anastasiadis, S. H.; Kafesaki, M.; Economou, E. N.; Soukoulis, C. M.


    Modern electronics have nowadays evolved to offer highly sophisticated devices. It is not rare; however, their operation can be affected or even hindered by the surrounding electromagnetic radiation. In order to provide protection from undesired external electromagnetic sources and to ensure their unaffected performance, electromagnetic shielding is thus necessary. In this work, both the electromagnetic and mechanical properties of graphite-based polymeric films are studied. The investigated films show efficient electromagnetic shielding performance along with good mechanical stiffness for a certain graphite concentration. To the best of our knowledge, the present study illustrates for the first time both the electromagnetic shielding and mechanical properties of the polymer composite samples containing graphite filler at such high concentrations (namely 60-70 %). Our findings indicate that these materials can serve as potential candidates for several electronics applications.

  9. SOC-DS computer code provides tool for design evaluation of homogeneous two-material nuclear shield (United States)

    Disney, R. K.; Ricks, L. O.


    SOC-DS Code /Shield Optimization Code-Direc Search/, selects a nuclear shield material of optimum volume, weight, or cost to meet the requirments of a given radiation dose rate or energy transmission constraint. It is applicable to evaluating neutron and gamma ray shields for all nuclear reactors.

  10. Experimental Evaluation of Geopolymer and ?Lunamer? Binders as Radioactive Shielding Materials for Space Applications Project (United States)

    National Aeronautics and Space Administration — The purpose of this project is to develop lunar regolith based geopolymer concrete and perform differential shielding studies on various geopolymer formulations to...

  11. UHMW-PE. A shielding material with special properties influenced by radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ehe, K. von der; Jaunich, M.; Wolff, D. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany)


    Ultra high molecular weight polyethylene (UHMW-PE) - due to its high hydrogen content - is used as neutron shielding material in casks for storage and transport of radioactive materials. Besides this, UHMW-PE - as a high-performance polymer - has been used for several years in medical technology due to its excellent slip and wear properties. Due to the special properties of UHMW-PE which result basically from its extreme chain lengths and its high degree of crystallinity, it is predestinated for the aforementioned applications. In both cases, irradiation and its impact on the molecular structure of polyethylene play an important role. In the first case, irradiation exists as a by-product of inserting the radioactive material in the cask. Hence PE has to withstand any type of degradation affecting safety relevant aspects to be applicable for long term radiation shielding purposes for instance over a period of 40 years. In the second case irradiation is applied deliberately for purposes such as sterilization and crosslinking, leading to partial improvement of the mechanical properties (e.g. fracture toughness, crack propagation resistance, wear resistance) and better chemical stability. Specifically concerning their use in the field of medical technology, different types of UHMW-PE have been objects of numerous publications. It is generally accepted that two parallel and competitive processes, based on chain scission and reactions of C-centered radicals and molecular fragments, occur in PE as a consequence of radiation: radical recombination accounts for crosslinking, together with some disproportionation, formation of low molecular weight fragments, and recrystallization. Furthermore, formation of oxygenated structures in the presence of traces of oxygen is an antagonist of the C-centered radicals. Radiation induced scission preferentially takes place in the amorphous phase and noncrystalline surface of the crystals. It is followed by folding of molecular fragments

  12. Innovative neutron shielding materials composed of natural rubber-styrene butadiene rubber blends, boron oxide and iron(III) oxide (United States)

    Jumpee, C.; Wongsawaeng, D.


    Optimized flexible and lightweight neutron shielding materials were designed using the Monte Carlo N-Particle (MCNP) code. Thicknesses of 10 mm and 100 mm were tested for neutron shielding performances. Simulation results indicated that the 10 mm shielding material of natural rubber (NR) and styrene butadiene rubber (SBR) blend (1:1) with 60 part per hundred rubber (phr) boron oxide (B2O3) and 100 mm shielding material with four alternating layers of NR with 100 phr iron (III) oxide (Fe2O3) and of NR and SBR blend (1:1) with 10 phr B2O3 were most suitable for thermal neutron shielding and all-energy neutron shielding, respectively. Experimental results verified the shielding efficiency of these optimal designs and ease of fabrication.

  13. Aluminum-titanium hydride-boron carbide composite provides lightweight neutron shield material (United States)

    Poindexter, A. M.


    Inexpensive lightweight neutron shield material has high strength and ductility and withstands high internal heat generation rates without excessive thermal stress. This composite material combines structural and thermal properties of aluminum, neutron moderating properties of titanium hydride, and neutron absorbing characteristics of boron carbide.

  14. Evaluation of Multi-Functional Materials for Deep Space Radiation Shielding (United States)

    Rojdev, Kristina; Atwell, William; Wilkins, Richard; Gersey, Brad; Badavi, Francis F.


    Small scale trade study of materials for radiation shielding: a) High-hydrogen polymers; b) Z-graded materials; c) Fiber-reinforced polymer composites. Discussed multi-functionality of fiber-reinforced polymer composites. Preliminary results of ground testing data.

  15. Hydrogen Absorbing Materials for Use as Radiation Shielding During Extended Space Flight Missions (United States)

    Grugel, Richard N.; Rose, M. Franklin (Technical Monitor)


    Minimizing radiation exposure from the galactic cosmic ray (GCR) environment during extended space missions is particularly crucial to crew health and safety. Here, an ideal candidate for shielding would be pure solid or liquid hydrogen, a material that effectively fragments heavy ions into ones of lower mass and energy that are more easily attenuated. Unfortunately, utilizing pure hydrogen is not presently feasible. It is, however, known that the hydrogen content of other materials (for example, metal hydrides, palladium alloys, and organic compounds) can exceed that of pure solid hydrogen and thus merit consideration as shielding candidates. This presentation will discuss an ongoing effort to develop novel shielding from such materials in concert with a coordinated testing/evaluation and modeling effort.

  16. Conservative method for determination of material thickness used in shielding of veterinary facilities; Metodo conservativo para determinacao de espessura de materiais utilizados para blindagem de instalacoes veterinarias

    Energy Technology Data Exchange (ETDEWEB)

    Lava, Deise D.; Borges, Diogo da S.; Affonso, Renato R.W.; Moreira, Maria de L.; Guimaraes, Antonio C.F., E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)


    For determination of an effective method for shielding of veterinary rooms, was provided shielding methods generally used in rooms which works with X-ray production and radiotherapy. Every calculation procedure is based in traditional variables used to transmission calculation. The thickness of the materials used for primary and secondary shieldings are obtained to respect the limits set by the Brazilian National Nuclear Energy Commission (CNEN). This work presents the development of a computer code in order to serve as a practical tool for determining rapid and effective materials and their thicknesses to shield veterinary facilities. The code determines transmission values of the shieldings and compares them with data from transmission 'maps' provided by NCRP-148 report. These 'maps' were added to the algorithm through interpolation techniques of curves of materials used for shielding. Each interpolation generates about 1,000,000 points that are used to generate a new curve. The new curve is subjected to regression techniques, which makes possible to obtain nine degree polynomial, and exponential equations. These equations whose variables consist of transmission of values, enable trace all the points of this curve with high precision. The data obtained from the algorithm were satisfactory with official data presented by the National Council of Radiation Protection and Measurements (NCRP) and can contribute as a practical tool for verification of shielding of veterinary facilities that require using Radiotherapy techniques and X-ray production.

  17. Potential Use of In Situ Material Composites such as Regolith/Polyethylene for Shielding Space Radiation (United States)

    Theriot, Corey A.; Gersey, Buddy; Bacon, Eugene; Johnson, Quincy; Zhang, Ye; Norman, Jullian; Foley, Ijette; Wilkins, Rick; Zhou, Jianren; Wu, Honglu


    NASA has an extensive program for studying materials and methods for the shielding of astronauts to reduce the effects of space radiation when on the surfaces of the Moon and Mars, especially in the use of in situ materials native to the destination reducing the expense of materials transport. The most studied material from the Moon is Lunar regolith and has been shown to be as efficient as aluminum for shielding purposes (1). The addition of hydrogenous materials such as polyethylene should increase shielding effectiveness and provide mechanical properties necessary of structural materials (2). The neutron radiation shielding effectiveness of polyethylene/regolith stimulant (JSC-1A) composites were studied using confluent human fibroblast cell cultures exposed to a beam of high-energy spallation neutrons at the 30deg-left beam line (ICE house) at the Los Alamos Neutron Science Center. At this angle, the radiation spectrum mimics the energy spectrum of secondary neutrons generated in the upper atmosphere and encountered when aboard spacecraft and high-altitude aircraft. Cell samples were exposed in series either directly to the neutron beam, within a habitat created using regolith composite blocks, or behind 25 g/sq cm of loose regolith bulk material. In another experiment, cells were also exposed in series directly to the neutron beam in T-25 flasks completely filled with either media or water up to a depth of 20 cm to test shielding effectiveness versus depth and investigate the possible influence of secondary particle generation. All samples were sent directly back to JSC for sub-culturing and micronucleus analysis. This presentation is of work performed in collaboration with the NASA sponsored Center for Radiation Engineering and Science for Space Exploration (CRESSE) at Prairie View A&M.

  18. Calculation of gamma-ray attenuation parameters for locally developed shielding material: Polyboron

    Directory of Open Access Journals (Sweden)

    Ripan Biswas


    Full Text Available In the present study, the mass attenuation coefficient (μm has been calculated analytically for a locally developed shielding material, polyboron, and compared with the values obtained from the WinXCom code, a Windows version of the XCOM database at the photon energy range 0.001 MeV–20 MeV. A good agreement has been observed between these two values. The linear attenuation coefficients (μ and relaxation lengths (λ have also been calculated from the obtained μm values and their variations with photon energy have been plotted. For comparison, other four shielding materials- ordinary concrete, pure polyethylene, borated polyethylene and water have also been studied. The obtained result shows that μm, μ and λ strongly depends on the photon energy, chemical composition and density of the shielding materials. The values of μm and μ of polyboron have been found greater than those of pure polyethylene and borated polyethylene but less than those of ordinary concrete and water at low photon energy range; and at the intermediate photon energy range (0.125 MeV–6 MeV, all the sample materials have approximately the same μm values. It has also been noticed that polyboron has the medial relaxation length (λ over the entire photon energy range. The total mass attenuation coefficient (μm and linear attenuation coefficient (μ, Half Value Layer (HVL and Tenth Value Layer (TVL of the five sample materials for some common gamma sources have been worked out and the transmission curves have been plotted. The curves exhibit that the transmission factor of the sample materials decreases with the increase in shielding thickness. The results of this study can be utilized to comprehend the shielding effectiveness of this locally developed material.


    Energy Technology Data Exchange (ETDEWEB)

    Jeffcoat, R.


    Detection and identification of shielded and masked nuclear materials is crucial to national security, but vast borders and high volumes of traffic impose stringent requirements for practical detection systems. Such tools must be be mobile, and hence low power, provide a low false alarm rate, and be sufficiently robust to be operable by non-technical personnel. Currently fielded systems have not achieved all of these requirements simultaneously. Transport modeling such as that done in GADRAS is able to predict observed spectra to a high degree of fidelity; our research is focusing on a radionuclide identification algorithm that inverts this modeling within the constraints imposed by a handheld device. Key components of this work include incorporation of uncertainty as a function of both the background radiation estimate and the hypothesized sources, dimensionality reduction, and nonnegative matrix factorization. We have partially evaluated performance of our algorithm on a third-party data collection made with two different sodium iodide detection devices. Initial results indicate, with caveats, that our algorithm performs as good as or better than the on-board identification algorithms. The system developed was based on a probabilistic approach with an improved approach to variance modeling relative to past work. This system was chosen based on technical innovation and system performance over algorithms developed at two competing research institutions. One key outcome of this probabilistic approach was the development of an intuitive measure of confidence which was indeed useful enough that a classification algorithm was developed based around alarming on high confidence targets. This paper will present and discuss results of this novel approach to accurately identifying shielded or masked radioisotopes with radiation detection systems.

  20. Nanotube Reinforced Multifunctional Materials for Radiation Shielding Project (United States)

    National Aeronautics and Space Administration — NASA's programs to send manned and unmanned missions to Moon, Mars and the planets beyond will require structural materials that can protect the crew and the...


    Institute of Scientific and Technical Information of China (English)

    苏镇涛; 周红梅; 胡向军; 杨国山


    To study the relation between the EM property and shielding efficiency of shielding material, the whole body averaged SAR and organ SARs of the shielding human model have been calculated using FDTD, the effects of different frequencies and different incidence angles have been studied too. The results show the whole body averaged SAR decreases with the improvement of shielding efficiency of shielding material. Because of the EM leakage of neckline, cuff and other openings, the whole body averaged SAR doesn't change obviously after it declines to a certain extent. Partial shielding method has the good shielding effect on the shielded organs. Compared with horizontal irradiation, the whole body averaged SAR increases substantially when being irradiated upward, and decreases when being irradiated downward.%本文采用高分辨率人体电磁辐射模型和非均匀网络时域有限差分法(FDTD),通过比较人体模型在防护前后全身平均比吸收率SAR的变化,建立了防护材料对人体防护性能的评价方法.利用此方法,针对不同频率、不同人射角度的电磁辐射,对不同防护材料的防护性能进行了评价.结果表明,防护材料的防护性能并不仅仅取决于其屏蔽性能,还与防护方式、照射方式等密切相关.局部防护方式对被防护的器官有良好的防护效果.相对于水平照射,斜向上照射时,防护效果较差;斜向下照射时,防护效果较好.

  2. Hypervelocity impact testing of advanced materials and structures for micrometeoroid and orbital debris shielding (United States)

    Ryan, Shannon; Christiansen, Eric L.


    A series of 66 hypervelocity impact experiments have been performed to assess the potential of various materials (aluminium, titanium, copper, stainless steel, nickel, nickel/chromium, reticulated vitreous carbon, silver, ceramic, aramid, ceramic glass, and carbon fibre) and structures (monolithic plates, open-cell foam, flexible fabrics, rigid meshes) for micrometeoroid and orbital debris (MMOD) shielding. Arranged in various single-, double-, and triple-bumper configurations, screening tests were performed with 0.3175 cm diameter Al2017-T4 spherical projectiles at nominally 6.8 km/s and normal incidence. The top performing shields were identified through target damage assessments and their respective weight. The top performing candidate shield at the screening test condition was found to be a double-bumper configuration with a 0.25 mm thick Al3003 outer bumper, 6.35 mm thick 40 PPI aluminium foam inner bumper, and 1.016 mm thick Al2024-T3 rear wall (equal spacing between bumpers and rear wall). In general, double-bumper candidates with aluminium plate outer bumpers and foam inner bumpers were consistently found to be amongst the top performers. For this impact condition, potential weight savings of at least 47% over conventional all-aluminium Whipple shields are possible by utilizing the investigated materials and structures. The results of this study identify materials and structures of interest for further, more in-depth, impact investigations.

  3. Self-closing shielded container for use with radioactive materials (United States)

    Smith, J.E.

    A container for storage of radioactive material comprises a container body and a closure member. The closure member is coupled to the container body to enable the closure body to move automatically from a first position (e.g., closed) to a second position (open).

  4. Structural and Radiation Shielding Properties of a Martian Habitat Material Synthesized From In-Situ Resources (United States)

    Sen, S.; Caranza, S.; Bhattacharya, M.; Makel, D. B.


    The 2 primary requirements of a Martian habitat structure include sufficient structural integrity and effective radiation shielding. In addition, the capability to synthesize such building materials primarily from in-situ resources would significantly reduce the cost associated with transportation of such materials and structures from earth. To demonstrate the feasibility of such an approach we have fabricated samples in the laboratory using simulated in-situ resources, evaluated radiation shielding effectiveness using radiation transport codes and radiation test data, and conducted mechanical properties testing. In this paper we will present experimental results that demonstrate the synthesis of polyethylene from a simulated Martian atmosphere and the fabrication of a composite material using simulated Martian regolith with polyethylene as the binding material. Results from radiation transport calculations and data from laboratory radiation testing using a 500 MeV/nucleon Fe beam will be discussed. Mechanical properties of the proposed composite as a function of composition and processing parameters will also be presented.

  5. Shielding structure analysis for LSDS facility

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hong Yeop; Kim, Jeong Dong; Lee, Yong Deok; Kim, Ho Dong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    The nuclear material (Pyro, Spent nuclear fuel) itself and the target material to generate neutrons is the LSDS system for isotopic fissile assay release of high intensity neutron and gamma rays. This research was performed to shield from various strong radiation. A shielding evaluation was carried out with a facilities model of LSDS system. The MCNPX 2.5 code was used and a shielding evaluation was performed for the shielding structure and location. The radiation dose based on the hole structure and location of the wall was evaluated. The shielding evaluation was performed to satisfy the safety standard for a normal person (1 μSv/h) and to use enough interior space. The MCNPX2.5 code was used and a dose evaluation was performed for the location of the shielding material, shielding structure, and hole structure. The evaluation result differs according to the shielding material location. The dose rate was small when the shielding material was positioned at the center. The dose evaluation result regarding the location of the shielding material was applied to the facility and the shielding thickness was determined (In 50 cm + Borax 5 cm + Out 45cm). In the existing hole structure, the radiation leak is higher than the standard. A hole structure model to prevent leakage of radiation was proposed. The general public dose limit was satisfied when using the concrete reinforcement and a zigzag structure. The shielding result will be of help to the facility shielding optimization.

  6. Textile materials for electromagnetic field shielding made with the use of nano- and micro-technology (United States)

    Brzeziński, Stefan; Rybicki, Tomasz; Karbownik, Iwona; Malinowska, Grażyna; Śledzińska, Katarzyna


    Studies have been carried out aimed at the development of structures and technology for making special multi-layer textile-polymeric systems of shielding electromagnetic field (EMF). The use of textiles as EMF shielding materials is commonly known, however the EMF attenuation obtained practically exclusively results from the reflection of EMF, while the materials used for this purpose as a rule, show poor EMF absorption abilities. The basic assumption for a new solution is the exploitation of the multiple internal reflection of incident EMF either in textile-polymeric coating materials containing fine-particle electromagnetic materials or in special textile structures. This paper presents the results of investigating the EMF shielding effectiveness of several selected and developed textile-polymeric materials in respect of both their practical applications (protective clothing elements, technical materials, masking elements, etc.) and the structure and content of components with various EMF reflection and absorption properties. The measurement method for independent determination of reflection and transmission coefficients with a wavequide applicator was used. The results obtained with the 2.5 GHz to 18 GHz frequency range show a low value of transmission coefficient (min. -35 dB) and accepted reflection attenuation from about -4 dB to -15 dB for higher frequencies.

  7. Hospital construction materials: poor shielding capacity with respect to signals transmitted by mobile telephones. (United States)

    Hanada, E; Watanabe, Y; Antoku, Y; Kenjo, Y; Nutahara, H; Nose, Y


    Electromagnetic interference (EMI) with electronic medical equipment by the handsets of mobile telephones is a well documented problem in hospitals. To gain information about how to build an EMI-free hospital and how to make rooms safe for mobile telephone handset use in the hospital building the authors measured the shielding capacities of a concrete wall, concrete blocks, a steel door, and steel-surfaced partition panels. The shielding capacities of these materials were 2-7 dB for the concrete wall, 6-8 dB for the concrete blocks, 19-27 dB for the steel door, and 20-37 dB for the steel-surfaced partition panels. These results indicate that care should be taken to shield electronic equipment from signals coming from neighboring rooms and from those under and above any patient room in which such equipment is in use. Electricity-conductive paint, electricity-conductive wallpaper, and electricity-conductive cloth are examples of inexpensive materials that can increase shielding capacity.

  8. Investigation of gold as a material for thermal radiation shielding (United States)

    Munshi, Amit Harenkumar

    CdS/CdTe thin film solar cells technology is one of the fastest growing carbon neutral energy sources in the world today. Manufacturing of CdS/CdTe solar modules is carried out at temperature in the range of 620350°C under a vacuum of 40 millitorr using a Heated Pocket Deposition (HPD) system in the materials engineering laboratory. Since this system operates in vacuum, majority of the heat loss is due to thermal radiation. The concept here is to conserve the heat by reflecting the infrared radiation back into the deposition system thus increasing the thermal efficiency. Various metals may be used but calculations show that using a Gold thin film mirror can effectively reflect almost 97% of the incident radiation, thus conserving energy required for the manufacturing process. However, a phenomenon called thermal grooving or island formation inhibits its use. Thermal grooving occurs when the stress concentration at the grain boundaries causes grain separation. This phenomenon is observed in thin gold films that are exposed to a temperature in excess of 350°C for over 3 to 5 hours. In this study, these films are exposed to temperature upto 620350°C for cycles as long as 200 hours. The goal of this research is to explore the solutions for elimination of the phenomenon of thermal grooving and thus extract maximum life out of these thin gold films for conservation of heat. After carefully exploring literature on past research and conducting experiments it was found that within the range of the films that were tested, a 2000 A350° film with a 150 A350° of Indium underlay showed the best performance after thermal annealing and testing.

  9. Potential space debris shield structure using impact-initiated energetic materials composed of polytetrafluoroethylene and aluminum (United States)

    Wu, Qiang; Zhang, Qingming; Long, Renrong; Zhang, Kai; Guo, Jun


    A whipple shield using Al/PTFE (polytetrafluoroethylene) energetic material to protect against space debris is presented. The hypervelocity impact characteristics were investigated experimentally using a two-stage light gas gun at velocities between 3 and 6 km/s. A good protection of the shield was obtained through comparative experiments which used the same bumper areal density. The results showed that the critical projectile diameter can be improved by 28% by contrast with the Christiansen ballistic limit equations. The Al/PTFE energetic material bumper can break up the projectile into smaller, less massive, and slower projectiles due to the combined effect of impact and explosion, thereby producing a sharp rise in the spacecraft protection ability.

  10. Evaluation of lunar regolith geopolymer binder as a radioactive shielding material for space exploration applications (United States)

    Montes, Carlos; Broussard, Kaylin; Gongre, Matthew; Simicevic, Neven; Mejia, Johanna; Tham, Jessica; Allouche, Erez; Davis, Gabrielle


    Future manned missions to the moon will require the ability to build structures using the moon's natural resources. The geopolymer binder described in this paper (Lunamer) is a construction material that consists of up to 98% lunar regolith, drastically reducing the amount of material that must be carried from Earth in the event of lunar construction. This material could be used to fabricate structural panels and interlocking blocks that have radiation shielding and thermal insulation characteristics. These panels and blocks could be used to construct living quarters and storage facilities on the lunar surface, or as shielding panels to be installed on crafts launched from the moon surface to deep-space destinations. Lunamer specimens were manufactured in the laboratory and compressive strength results of up to 16 MPa when cast with conventional methods and 37 MPa when cast using uniaxial pressing were obtained. Simulation results have shown that the mechanical and chemical properties of Lunamer allow for adequate radiation shielding for a crew inside the lunar living quarters without additional requirements.

  11. Flexible EMI shielding materials derived by melt blending PVDF and ionic liquid modified MWNTs (United States)

    Sharma, Maya; Sharma, Sukanya; Abraham, Jiji; Thomas, Sabu; Madras, Giridhar; Bose, Suryasarathi


    Nano composites of PVDF with ionic liquid [EMIM][TF2N] (IL) modified MWNTs were prepared by melt blending to design materials for EMI shielding applications. MWNTs and IL were mixed in two different ratios (1:1 and 1:5) to facilitate better dispersion of MWNTs in PVDF. It was observed that non-covalent interactions between IL and PVDF resulted in a better dispersion of CNTs and was consistent with increasing concentration of IL. Interestingly, IL modified MWNTs induced the formation of γ-phase crystals in PVDF, which was further confirmed by XRD, FTIR and DSC. Melt rheological measurements and DSC analysis revealed the plasticization effect of IL in PVDF composites further manifesting in a decrease in the storage modulus and the glass transition temperature. This phenomenal effect presumably led to better dispersion of IL modified MWNTs in PVDF further resulting in a significant improvement in electrical conductivity and structural properties. More interestingly, the elongational properties in the composites improved with IL modified MWNTs in striking contrast to MWNT filled PVDF composites. The ac conductivity of the composites reached about 10-3 S cm-1 with the addition of 2 wt% IL modified MWNTs (1:1). This further led to a high electro-magnetic interference (EMI) shielding effectiveness of about 20 dB at 2 wt% IL modified MWNTs. Such materials can further be explored for flexible, lightweight EMI shielding materials for a wide range of operating frequency.

  12. Shielding behaviors of some polymer and plastic materials for gamma-rays (United States)

    Mann, Kulwinder Singh; Rani, Asha; Heer, Manmohan Singh


    Gamma-rays interaction parameters with six polymer and plastic materials have been computed and investigated for their shielding behaviours in the experimental energy range 10-1400 keV. Low mass-density and ability to transform into thin-sheets of H-containing plastic and polymer materials generate the curiosity for present study. Gamma Ray Interaction Coefficients (GRIC)-toolkit: a computer program designed in MS-Excel, 2007 for the investigation. The toolkit has the capability to compute different parameters linked to shielding properties of the sample-material such that; mass attenuation coefficients (μ/ρ), mass energy absorption coefficients (μen/ρ), equivalent atomic number (Zeq), KERMA (kinetic energy released per unit mass). Polyvinyl Chloride (PVC) seems to be the best shield for gamma radiations in energy range 10-110 keV. The interaction parameters for selected samples have been computed and provided in the extended energy range 0.015-15 MeV.

  13. The investigation of vermiculite as an alternating shielding material for gamma rays (United States)

    Gülbiçim, Hasan; Tufan, M. Çağatay; Türkan, M. Nureddin


    In this study, gamma ray shielding properties of vermiculite has been investigated for the first time as a shielding material. The photon total mass attenuation coefficients μm, the half value layer (HVL), the tenth value layer (TVL) and the mean free path (MFP) values have been experimentally determined for the photon energies at 0.244, 0.262, 0.342, 0.600, 0.778, 1.173, 1.332, 1.408 and 1.728 MeV. The theoretical data are calculated by using WinXCom computer code. At the end, we obtained good agreement between experimental and theoretical values. As well as the total mass attenuation coefficients, we have also calculated the effective atomic number, Zeff, the effective electron number, Neff, the total atomic cross-section, σt,a, the total electronic cross-section, σt,e, values for vermiculite and some building materials. Consequently, the obtained results showed that vermiculite could be used as a shielding material for gamma radiation.

  14. Lightweight nanocomposites based on poly(vinylidene fluoride) and Al nanoparticles: Structural, thermal and mechanical characterization and EMI shielding capability

    Energy Technology Data Exchange (ETDEWEB)

    Arranz-Andrés, J., E-mail: [Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid (Spain); Pulido-González, N. [Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid (Spain); Fonseca, C. [POLCA, Departamento de Química Industrial y Polímeros, E. T. de Ingenieros Industriales, Universidad Politécnica de Madrid, Ronda de Valencia, 3, 28012 Madrid (Spain); Pérez, E.; Cerrada, M.L. [Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid (Spain)


    Novel (nano)composites based on PVDF and different content of Al nanoparticles have been prepared in order to learn about their electromagnetic interference shielding capability. Very promising results are obtained, with an excellent balance between shielding and sample weight, so that these materials are potentially good alternatives to replace neat metals for that application. Moreover, a complete structural and morphological characterization, as well as an evaluation of their thermal and mechanical behavior, has been also performed. - Graphical abstract: EMI shielding capability in lightweight nanocomposites based on poly(vinylidene fluoride) and Al nanoparticles. - Highlights: • Novel hybrids based on PVDF and different contents of Al nanoparticles have been prepared. • A complete characterization of the nanocomposites has been performed. • Interactions between PVDF matrix and Al nanoparticles are deduced from FTIR. • Attenuation of the electromagnetic radiation increases spectacularly with the Al content.

  15. Use of CR-39 films for nuclear radiation shielding efficacy evaluation of lining materials for combat vehicles (United States)

    Gopalani, Deepak; Jodha, A. S.; Das, M. K.; Singh, R. K.; Baheti, G. L.


    All materials provide, to a lesser or greater extent, shielding against nuclear radiations. Armoured fighting vehicles (AFVs) have steel as the structural material, which appears to be a reasonably good gamma and neutron shield material but a shield of pure iron would not be equally effective against whole range of neutron energies as it has a few resonances in electron volt range, and it reduces energy of fast neutrons to lower energy neutrons. These neutrons will be absorbed through radiative capture and emit gamma radiations. Thus it is essential that an effective shield should contain a large amount of moderating material, hydrogen being preferred with low atomic number materials (B, C, Li) and lead (Pb) to ensure that the neutrons do not diffuse at intermediate energies in the shield as well as gamma attenuation will also take place. In order to have a suitable shield material for armoured vehicles which serves as neutron and gamma radiation attenuator, polyethylene polymer with fillers lining materials are preferred. These materials were evaluated against gamma and fast neutrons using radioactive sources for suitability to fitment into combat vehicle as per the requirement of protection factor values. The detector for gamma radiation was used as Nal(Tl) while for neutron, CR-39 film was used.

  16. Shielding Effectiveness of Laminated Shields

    Directory of Open Access Journals (Sweden)

    B. P. Rao


    Full Text Available Shielding prevents coupling of undesired radiated electromagnetic energy into equipment otherwise susceptible to it. In view of this, some studies on shielding effectiveness of laminated shields with conductors and conductive polymers using plane-wave theory are carried out in this paper. The plane wave shielding effectiveness of new combination of these materials is evaluated as a function of frequency and thickness of material. Conductivity of the polymers, measured in previous investigations by the cavity perturbation technique, is used to compute the overall reflection and transmission coefficients of single and multiple layers of the polymers. With recent advances in synthesizing stable highly conductive polymers these lightweight mechanically strong materials appear to be viable alternatives to metals for EM1 shielding.

  17. Measurements of gamma-ray production cross sections for shielding materials of space nuclear systems (United States)

    Orphan, V. J.; John, J.; Hoot, C. G.


    Measurements of secondary gamma ray production from neutron interactions have been made over the entire energy range of interest in shielding applications. The epithermal capture gamma ray yields for both resolved gamma ray lines and continuum have been measured from thermal energies to 100 KeV for natural tungsten and U-238, two important candidate shield materials in SNAP reactor systems. Data are presented to illustrate the variation of epithermal capture gamma ray yields with neutron energy. The gamma ray production cross sections from (n,xy) reactions have been measured for Fe and Al from the threshold energies for inelastic scattering to approximately 16 MeV. Typical Fe and Al cross sections obtained with high-neutron energy resolution and averaged over broad neutron-energy groups are presented.

  18. Beam loss reduction by magnetic shielding using beam pipes and bellows of soft magnetic materials (United States)

    Kamiya, J.; Ogiwara, N.; Hotchi, H.; Hayashi, N.; Kinsho, M.


    One of the main sources of beam loss in high power accelerators is unwanted stray magnetic fields from magnets near the beam line, which can distort the beam orbit. The most effective way to shield such magnetic fields is to perfectly surround the beam region without any gaps with a soft magnetic high permeability material. This leads to the manufacture of vacuum chambers (beam pipes and bellows) with soft magnetic materials. A Ni-Fe alloy (permalloy) was selected for the material of the pipe parts and outer bellows parts, while a ferritic stainless steel was selected for the flanges. An austenitic stainless steel, which is non-magnetic material, was used for the inner bellows for vacuum tightness. To achieve good magnetic shielding and vacuum performances, a heat treatment under high vacuum was applied during the manufacturing process of the vacuum chambers. Using this heat treatment, the ratio of the integrated magnetic flux density along the beam orbit between the inside and outside of the beam pipe and bellows became small enough to suppress beam orbit distortion. The outgassing rate of the materials with this heat treatment was reduced by one order magnitude compared to that without heat treatment. By installing the beam pipes and bellows of soft magnetic materials as part of the Japan Proton Accelerator Research Complex 3 GeV rapid cycling synchrotron beam line, the closed orbit distortion (COD) was reduced by more than 80%. In addition, a 95.5% beam survival ratio was achieved by this COD improvement.

  19. Beam loss reduction by magnetic shielding using beam pipes and bellows of soft magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Kamiya, J., E-mail:; Ogiwara, N.; Hotchi, H.; Hayashi, N.; Kinsho, M.


    One of the main sources of beam loss in high power accelerators is unwanted stray magnetic fields from magnets near the beam line, which can distort the beam orbit. The most effective way to shield such magnetic fields is to perfectly surround the beam region without any gaps with a soft magnetic high permeability material. This leads to the manufacture of vacuum chambers (beam pipes and bellows) with soft magnetic materials. A Ni–Fe alloy (permalloy) was selected for the material of the pipe parts and outer bellows parts, while a ferritic stainless steel was selected for the flanges. An austenitic stainless steel, which is non-magnetic material, was used for the inner bellows for vacuum tightness. To achieve good magnetic shielding and vacuum performances, a heat treatment under high vacuum was applied during the manufacturing process of the vacuum chambers. Using this heat treatment, the ratio of the integrated magnetic flux density along the beam orbit between the inside and outside of the beam pipe and bellows became small enough to suppress beam orbit distortion. The outgassing rate of the materials with this heat treatment was reduced by one order magnitude compared to that without heat treatment. By installing the beam pipes and bellows of soft magnetic materials as part of the Japan Proton Accelerator Research Complex 3 GeV rapid cycling synchrotron beam line, the closed orbit distortion (COD) was reduced by more than 80%. In addition, a 95.5% beam survival ratio was achieved by this COD improvement.

  20. Use of CR 39 Films for Evaluation of Shielding Efficacy of Materials against Fast Neutrons



    CR-39 films have been used for evaluation of neutron shielding of metal alloys, different types of rubbers, sand polymers, etc. These films have been chosen because of their ability to record fast neutrons from 200 keV-10 MeV and their insensitivity to gamma radiations. Tenth value layer (TVL) for the materials studied varies from 10.5 to 28.6 cm. In addition, the values of TVL have also been computed for standard material, such as Al, steel, etc. Using neutron removal cross-section da...


    Directory of Open Access Journals (Sweden)

    BELOUSOVA Elena Sergeevna


    Full Text Available Today when specific shielded facilities are designed the construction materials and shields should meet a range of fire safety requirements. A composite coating on the basis of a water-based fire-resistant paint filled with shungite nanopowder can be applied onto walls, floors, ceilings and other surfaces in the shielded areas to reduce electromagnetic radiation and simultaneously to ensure fire safety. Shungit is a mineral with multilayer carbon fullerene globules which diameter is 10–30 nm. Due to the high conductivity shungite is able to weaken electromagnetic radiation. A coating made of schungite-containing paint on a cellulose substrate was subjected to the open flame under the temperature of 1700° C for 3 minutes and 40 seconds. That resulted in the formation of insulating foam layer without mechanical damage of the substrate. The XRD diffraction analysis of the powder obtained in the process of flame influence on the coating showed the formation of the such substances as orthoclase, barite, rutile, etc. Carbon contained in shungit and used as a filler for the fireproof paint wasn’t detected. This fact indicates carbon oxidation as the result of its burning out. The shielding efficiency of the composite coating after open flame exposure was measured for the frequency range 8…12 GHz with the use of the panoramic attenuation meter and voltage standing wave ratio meter YA2R-67-61 with a sweep generator and waveguides. After that the reflection and transmission coefficients were calculated. The results of measurements and calculations showed decrease of the reflection and transmission coefficients due to conductivity decrease and dielectric losses changes of the composite coating provided by silica content increase and carbon percentage decrease.

  2. Long term testing of materials for tube shielding, stage 2; Laangtidsprovning av tubskyddsmaterial, etapp 2

    Energy Technology Data Exchange (ETDEWEB)

    Norling, Rikard; Hjoernhede, Anders; Mattsson, Mattias


    Circulating Fluidized Bed (CFB) boilers are commonly used for combustion of biomass and are used to some extent for Waste-to-Energy (WtE) plants as well. The superheaters of the latter are for obvious reasons more prone to suffer from high temperature corrosion caused by the corrosive species in the fuel, mainly chlorides. Frequently the final (hottest) superheater is positioned in the loop seal, where the circulating bed material is returned to the furnace after being separated from the flue gas by a cyclone. The environment in the loop seal is relatively free of chlorides, since these primarily follow the flue gas into the convection pass. Hence, higher steam temperature can be allowed without excessive damage to the final superheater. On the other hand the superheaters, which are located in the convection pass, are more exposed to the corrosive species of the flue gas. Further, they are eroded by particles entrained in the gas flow. Particles and condensing gaseous species are to a large extent deposited on the superheaters, which limits the heat transfer and promotes corrosion. The deposits are regularly removed e.g. by soot blowers. The pressurized steam from soot blowers causes additional erosion damage to that caused by entrained particles. It shall be noted that the actual damage is caused by a combined mechanism of erosion and corrosion denoted erosion-corrosion, which usually results in dramatically accelerated wear. To avoid excessive erosion damage on the superheater tubes the first tube row of each bundle is protected by tube shielding. In its simplest form the shields are made from a steel sheet that has been bent into a semi-circular half-cylinder shell. These shields are attached onto the wind-side of the tubes by hangers. A typical material for tube shielding is the austenitic high temperature resistant stainless steel 253MA. Life of tube shielding depends on numerous factors such as boiler design, superheater location, fuel and operating

  3. Ion-Electron-Conducting Polymer Composites: Promising Electromagnetic Interference Shielding Material. (United States)

    Vyas, Manoj Kumar; Chandra, Amita


    Polymer nanocomposites consisting of poly(vinylidenefluoride-co-hexafluoropropylene) PVdF-HFP, inorganic salt (LiBF4), organic salt (EMIMBF4), multiwalled carbon nanotubes (MWCNTs), and Fe3O4 nanoparticles were prepared as electromagnetic shield material. Improvement in conductivity and dielectric property due to the introduction of EMIMBF4, LiBF4, and MWCNTs was confirmed by complex impedance spectroscopy. The highest conductivity obtained is ∼1.86 mS/cm. This is attributed to the high ionic conductivity of the ionic liquids and the formation of a connecting network by the MWCNTs facilitating electron conduction. The total electromagnetic interference (EMI) shielding effectiveness has a major contribution to it due to absorption. Although the total shielding effectiveness in the Ku band (12.4-18 GHz) of pure ion-conducting system was found to be ∼19 dB and that for the polymer composites which are mixed (ion + electron) conductors is ∼46 dB, the contributions due to absorption are ∼16 and ∼42 dB, respectively.

  4. Monte Carlo simulation of photon buildup factors for shielding materials in radiotherapy x-ray facilities

    Energy Technology Data Exchange (ETDEWEB)

    Karim Karoui, Mohamed [Faculte des Sciences de Monastir, Avenue de l' environnement 5019 Monastir -Tunisia (Tunisia); Kharrati, Hedi [Ecole Superieure des Sciences et Techniques de la Sante de Monastir, Avenue Avicenne 5000 Monastir (Tunisia)


    Purpose: This paper presents the results of a series of calculations to determine buildup factors for ordinary concrete, baryte concrete, lead, steel, and iron in broad beam geometry for photons energies from 0.125 to 25.125 MeV at 0.250 MeV intervals.Methods: Monte Carlo N-particle radiation transport computer code has been used to determine the buildup factors for the studied shielding materials.Results: The computation of the primary broad beams using buildup factors data was done for nine published megavoltage photon beam spectra ranging from 4 to 25 MV in nominal energies, representing linacs made by the three major manufacturers. The first tenth value layer and the equilibrium tenth value layer are calculated from the broad beam transmission for these nine primary megavoltage photon beam spectra.Conclusions: The results, compared with published data, show the ability of these buildup factor data to predict shielding transmission curves for the primary radiation beam. Therefore, the buildup factor data can be combined with primary, scatter, and leakage x-ray spectra to perform computation of broad beam transmission for barriers in radiotherapy shielding x-ray facilities.

  5. High Kinetic Energy Penetrator Shielding and High Wear Resistance Materials Fabricated with Boron Nitride Nanotubes (BNNTS) and BNNT Polymer Composites (United States)

    Kang, Jin Ho (Inventor); Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor); Lowther, Sharon E. (Inventor); Bryant, Robert George (Inventor)


    Boron nitride nanotubes (BNNTs), boron nitride nanoparticles (BNNPs), carbon nanotubes (CNTs), graphites, or combinations, are incorporated into matrices of polymer, ceramic or metals. Fibers, yarns, and woven or nonwoven mats of BNNTs are used as toughening layers in penetration resistant materials to maximize energy absorption and/or high hardness layers to rebound or deform penetrators. They can be also used as reinforcing inclusions combining with other polymer matrices to create composite layers like typical reinforcing fibers such as Kevlar.RTM., Spectra.RTM., ceramics and metals. Enhanced wear resistance and usage time are achieved by adding boron nitride nanomaterials, increasing hardness and toughness. Such materials can be used in high temperature environments since the oxidation temperature of BNNTs exceeds C. in air. Boron nitride based composites are useful as strong structural materials for anti-micrometeorite layers for spacecraft and space suits, ultra strong tethers, protective gear, vehicles, helmets, shields and safety suits/helmets for industry.

  6. Multifunctional, Boron-Foam Based Radiation Shielding Project (United States)

    National Aeronautics and Space Administration — The NASA vision of Space Exploration requires new approaches to radiation shielding. Both Spiral 2 and Spiral 3 concepts are extremely sensitive to weight reduction....

  7. Preparation of Y2O3/GeO2/Epoxy Resin Based Multilayer Radiation Shielding Material and its Property Research%Y2 O3/GeO2/环氧树脂基辐射防护材料的制备及性能研究

    Institute of Scientific and Technical Information of China (English)

    代旭之; 肖德涛


    用表面处理稀土氧化物Y2O3,GeO2的方法制备了Y2O3/GeO2/环氧树脂辐射防护材料。采用X射线衍射仪( XRD )研究了材料的微观结构;用多道γ谱仪测试并分析了材料的辐射防护能力。结果表明,制得的材料中的Y2 O3和GeO2粒子并未与环氧树脂发生键和反应,Y2 O3与GeO2粉末的加入明显提升了材料防护射线的效果。%Y2 O3/GeO2/Epoxy Resin Based Multilayer Radiation Shielding Material was pre-pared for radiation protection via route of surface treatment on Y2O3 and GeO2.The material’s microstructure was studied by X-ray diffraction( XRD);Radiation shielding property was cal-culated by gamma energy spectrum system.Results show that the obtained materials of Y2O3 and GeO2 particles was not with the key and the reaction of epoxy resin,the material’s shield capability is significantly improved by addition of Y2 O3 and GeO2 powder.

  8. Geant4 calculations for space radiation shielding material Al2O3 (United States)

    Capali, Veli; Acar Yesil, Tolga; Kaya, Gokhan; Kaplan, Abdullah; Yavuz, Mustafa; Tilki, Tahir


    Aluminium Oxide, Al2O3 is the most widely used material in the engineering applications. It is significant aluminium metal, because of its hardness and as a refractory material owing to its high melting point. This material has several engineering applications in diverse fields such as, ballistic armour systems, wear components, electrical and electronic substrates, automotive parts, components for electric industry and aero-engine. As well, it is used as a dosimeter for radiation protection and therapy applications for its optically stimulated luminescence properties. In this study, stopping powers and penetrating distances have been calculated for the alpha, proton, electron and gamma particles in space radiation shielding material Al2O3 for incident energies 1 keV - 1 GeV using GEANT4 calculation code.

  9. Geant4 calculations for space radiation shielding material Al2O3

    Directory of Open Access Journals (Sweden)

    Capali Veli


    Full Text Available Aluminium Oxide, Al2O3 is the most widely used material in the engineering applications. It is significant aluminium metal, because of its hardness and as a refractory material owing to its high melting point. This material has several engineering applications in diverse fields such as, ballistic armour systems, wear components, electrical and electronic substrates, automotive parts, components for electric industry and aero-engine. As well, it is used as a dosimeter for radiation protection and therapy applications for its optically stimulated luminescence properties. In this study, stopping powers and penetrating distances have been calculated for the alpha, proton, electron and gamma particles in space radiation shielding material Al2O3 for incident energies 1 keV – 1 GeV using GEANT4 calculation code.

  10. The gamma-ray and neutron shielding factors of fly-ash brick materials. (United States)

    Singh, Vishwanath P; Badiger, N M


    A comprehensive study of gamma-ray exposure build-up factors (EBFs) of fly-ash brick materials has been carried out for photon energies of 0.015-15 MeV up to a penetration depth of 40 mfp (mean free path) by a geometrical progression (GP) fitting method. The EBF values of the fly-ash brick materials were found to be dependent upon the photon energy, penetration depth and chemical composition, and were found to be higher than the values for mud bricks and common bricks. Above a photon energy of 3 MeV for large penetration depths (>10 mfp), the EBF becomes directly proportional to Zeq. EBFs of fly-ashes were found to be less than or equal to those of concrete for low penetration depths (shielding effectiveness. The shielding effectiveness of the fly-ash materials against gamma-ray radiation was lower than that of common and mud bricks.

  11. Diagnostic X-ray shielding design based on an empirical model of photon attenuation

    Energy Technology Data Exchange (ETDEWEB)

    Archer, B.R.; Thornby, J.I.; Bushong, S.C.


    A series of nomograms that simplify determination of diagnostic X-ray shielding requirements with lead are presented. All recommendations of the NCRP, except that to ''add one half value layer'' in determining secondary barriers, were followed in the production of these curves. For secondary barriers, the shielding required to reduce the weekly exposure to the applicable MPD has been determined. This eliminates the over-shielding inherent in the ''add one HVL'' approximation and allows a variety of more cost effective materials to be considered for secondary barriers.

  12. Diagnostic x-ray shielding design based on an empirical model of photon attenuation

    Energy Technology Data Exchange (ETDEWEB)

    Archer, B.R. (Radiation Safety Office, Houston, TX); Thornby, J.I.; Bushong, S.C.


    A series of nomograms that simplify determination of diagnostic X-ray shielding requirements with lead are presented. All recommendations of the NCRP, except that to ''add one half value layer'' in determining secondary barriers, were followed in the production of these curves. For secondary barriers, the shielding required to reduce the weekly exposure to the applicable MPD has been determined. This eliminates the over-shielding inherent in the ''add one HVL'' approximation and allows a variety of more cost effective materials to be considered for secondary barriers.

  13. Polymeric Materials With Additives for Durability and Radiation Shielding in Space (United States)

    Kiefer, Richard


    Polymeric materials are attractive for use in space structures because of their light weight and high strength In addition, polymers are made of elements with low atomic numbers (Z), primarily carbon (C), hydrogen (H), oxygen (0), and nitrogen (N) which provide the best shielding from galactic cosmic rays (GCR) (ref. 1). Galactic cosmic rays are composed primarily of nuclei (i.e., fully ionized atoms) plus a contribution of about 2% from electrons and positrons. There is a small but significant component of GCR particles with high charge (Z > 10) and high energy (E >100 GeV) (ref. 2). These so-called HZE particles comprise only 1 to 2% of the cosmic ray fluence but they interact with very high specific ionization and contribute 50% of the long- term dose to humans. The best shield for this radiation would be liquid hydrogen, which is not feasible. For this reason, hydrogen-containing polymers make the most effective practical shields. Moreover, neutrons are formed in the interactions of GCR particles with materials. Neutrons can only lose energy by collisions or reactions with a nucleus since they are uncharged. This is a process that is much less probable than the Coulombic interactions of charged particles. Thus, neutrons migrate far from the site of the reaction in which they were formed. This increases the probability of neutrons reaching humans or electronic equipment. Fast neutrons (> 1 MeV) can interact with silicon chips in electronic equipment resulting in the production of recoil ions which can cause single event upsets (SEU) in sensitive components (ref. 3). Neutrons lose energy most effectively by elastic collisions with light atoms, particularly hydrogen atoms. Therefore, hydrogen-containing polymers are not only effective in interacting with GCR particles; they are also effective in reducing the energy of the neutrons formed in the interactions.

  14. Carbon nanostructure composite for electromagnetic interference shielding

    Indian Academy of Sciences (India)

    Anupama Joshi; Suwarna Datar


    This communication reviews current developments in carbon nanostructure-based composite materials for electromagnetic interference (EMI) shielding. With more and more electronic gadgets being used at different frequencies, there is a need for shielding them from one another to avoid interference. Conventionally, metal-based shielding materials have been used. But due to the requirement of light weight, corrosion resistive materials, lot of work is being done on composite materials. In this research the forerunner is the nanocarbon-based composite material whose different forms add different characteristics to the composite. The article focusses on composites based on graphene, graphene oxide, carbon nanotubes, and several other novel forms of carbon.

  15. The performance test of anti-scattering x-ray grid with inclined shielding material by MCNP code simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jun Woo; Kim, Hee Reyoung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)


    The scattered photons cause reduction of the contrast of radiographic image and it results in the degradation of the quality of the image. In order to acquire better quality image, an anti-scattering x-ray gird should be equipped in radiography system. The X-ray anti-scattering grid of the inclined type based on the hybrid concept for that of parallel and focused type was tested by MCNP code. The MCNPX 2.7.0 was used for the simulation based test. The geometry for the test was based on the IEC 60627 which was an international standard for diagnostic X-ray imaging equipment-Characteristics of general purpose and mammographic anti-scatter grids. The performance of grids with four inclined shielding material types was compared with that of the parallel type. The grid with completely tapered type the best performance where there were little performance difference according to the degree of inclination.

  16. Resistivity, ESR, and Radiation Shielding Properties of the Volcanic Rock Materials

    Directory of Open Access Journals (Sweden)

    Çiğdem Nuhoğlu


    Full Text Available Pumices have been used in cement, concrete, brick, and ceramic industries as an additive and aggregate material. It will be important to study pumice types by using a different tool as EPR which is a new technique for related material to be used for industrial aims. Electron spin resonance (ESR spectra of the pumice types were taken by EMX-type spectrometer. Also, the current-voltage (I-V and surface resistivity probe stand of the thin films was studied using a four-point probe measurements. The relationship between radiation shielding properties of the pumice samples and their surface resistivity, chemical, and electrokinetic properties was evaluated using simple regression analysis. Simple regression analysis indicated a strong correlation between surface resistivity and density and SiO2, Fe2O3, CaO, MgO, and TiO2 content of pumice samples in this study. It is found that a correlation between determined g-factor by EPR spectroscopy and radiation shielding is established for pumice samples.

  17. Development and Study of Hard-Facing Materials on the Base of Heat-Resisting High-Hardness Steels for Plasma-Jet Hard- Facing in Shielding-Doping Nitrogen Atmosphere (United States)

    Malushin, N. N.; Kovalev, A. P.; Valuev, D. V.; Shats, E. A.; Borovikov, I. F.


    The authors develop hard-facing materials on the base of heat-resisting highhardness steels for plasma-jet hard-facing in nitrogen atmosphere for manufacturing parts of mining and metallurgic equipment which significantly simplify the production process and effect a saving when producing bimetallic parts and tools.

  18. Study on photon sensitivity of silicon diodes related to materials used for shielding (United States)

    Moiseev, T.


    Large area silicon diodes used in electronic neutron dosemeters have a significant over-response to X- and gamma-rays, highly non-linear at photon energies below 200 keV. This over-response to photons is proportional to the diode's active area and strongly affects the neutron sensitivity of such dosemeters. Since silicon diodes are sensitive to light and electromagnetic fields, most diode detector assemblies are provided with a shielding, sometimes also used as radiation filter. In this paper, the influence of materials covering the diode's active area is investigated using the MCNP-4A code by estimating the photon induced pulses in a typical silicon wafer (300 μm thickness and 1 cm diameter) when provided with a front case cover. There have been simulated small-size diode front covers made of several materials with low neutron interaction cross-sections like aluminium, TEFLON, iron and lead. The estimated number of induced pulses in the silicon wafer is calculated for each type of shielding at normal photon incidence for several photon energies from 9.8 keV up to 1.15 MeV and compared with that in a bare silicon wafer. The simulated pulse height spectra show the origin of the photon-induced pulses in silicon for each material used as protective cover: the photoelectric effect for low Z front case materials at low-energy incident photons (up to about 65 keV) and the Compton and build-up effects for high Z case materials at higher photon energies. A simple means to lower and flatten the photon response of silicon diodes over an extended X- and gamma rays energy range is proposed by designing a composed photon filter.

  19. Structural/Radiation-Shielding Epoxies (United States)

    Connell, John W.; Smith, Joseph G.; Hinkley, Jeffrey; Blattnig, Steve; Delozier, Donavon M.; Watson, Kent A.; Ghose, Sayata


    A development effort was directed toward formulating epoxy resins that are useful both as structural materials and as shielding against heavy-ion radiation. Hydrogen is recognized as the best element for absorbing heavy-ion radiation, and high-hydrogen-content polymers are now in use as shielding materials. However, high-hydrogen-content polymers (e.g. polyethylene) are typically not good structural materials. In contrast, aromatic polymers, which contain smaller amounts of hydrogen, often have the strength necessary for structural materials. Accordingly, the present development effort is based on the concept that an ideal structural/ heavy-ion-radiation-shielding material would be a polymer that contains sufficient hydrogen (e.g., in the form of aliphatic molecular groups) for radiation shielding and has sufficient aromatic content for structural integrity.

  20. Cuantificación de la contaminación del gas de protección en procesos de soldadura con arco eléctrico por medio de mediciones de oxígeno en la superficie del material base Quantification of contamination of the shielding gas in arc welding processes through measurement of oxygen on the surface of the base material

    Directory of Open Access Journals (Sweden)

    Julio Fuentes-Muñoz


    Full Text Available A metodologia apresentada neste trabalho se baseia em medições do teor de oxigênio na superfície do metal base, possibilitando assim, uma avaliação quantitativa da contaminação do gás de proteção. Os gases utilizados nos processos de soldagem definem as características do arco e protegem a poça de soldagem. A contaminação do gás, por exemplo, com o ar do meio ambiente, prejudica as propriedades da união soldada. A contaminação do gás de proteção não é somente dependente da qualidade do gás utilizado, como também tem que ser considerado os componentes contidos na tocha. Até agora, o nível da contaminação do gás produzido pela tocha tem sido analisado somente de forma empírica, avaliando a qualidade e forma do cordão de solda. A medição do oxigênio na superfície do metal de base é um método simples e preciso para analisar o nível de contaminação do gás de proteção. Este procedimento permite uma avaliação quantitativa, inclusive na presença do arco. No contexto deste trabalho se apresentará por meio de exemplos em tochas TIG e MIG/MAG as possibilidades da utilização desta metodologia para o desenvolvimento e análise de processos de soldagem a arco.The method presented in this paper is based on the measurement of oxygen on the surface of the base metal to enable a quantitative assessment of the contamination in the shielding gas. The gas used in arc processes affected arc properties and simultaneously protected the welding pool. The contamination of the shielding gases, e.g. with atmospheric air, damages the properties of the weld joint. The contamination in the shielding gas is not only dependent on the purity of the utilized gas, but also on the components of the welding torch. The level of contamination in the gas produced by the torch had been analyzed so far only by empirical evaluation of the quality and appearance of the welding seam. The measurement of oxygen on the surface of the base

  1. Use of CR 39 Films for Evaluation of Shielding Efficacy of Materials against Fast Neutrons

    Directory of Open Access Journals (Sweden)

    S. Kumar


    Full Text Available CR-39 films have been used for evaluation of neutron shielding of metal alloys, different types of rubbers, sand polymers, etc. These films have been chosen because of their ability to record fast neutrons from 200 keV-10 MeV and their insensitivity to gamma radiations. Tenth value layer (TVL for the materials studied varies from 10.5 to 28.6 cm. In addition, the values of TVL have also been computed for standard material, such as Al, steel, etc. Using neutron removal cross-section data, the results have been compared with those of experimentally determined values. The results seem to be in agreement within approximate 10 per cent variation.

  2. Comprehensive study on the light shielding potential of thermotropic layers for the development of new materials. (United States)

    Gruber, D P; Winkler, G; Resch, K


    In recent years thermotropic overheating protection glazings have been the focus for both solar thermal collector technology and architecture. A thermotropic glazing changes its light transmittance from highly transparent to light diffusing upon reaching a certain threshold temperature autonomously and reversibly. In thermotropic systems with fixed domains (TSFD) the scattering domains are embedded in a polymer matrix, which exhibits a sudden change of the refractive index upon reaching a threshold temperature. The aim of the present study was to comprehensively investigate the light shielding characteristics and potential of TSFD materials by applying simulation of light scattering in particle-filled layers. In random walk simulations a variety of parameters were varied systematically, and the effect on the light transmission behavior of TSFD was studied. The calculation steps of the simulation process are shown in detail. The simulations demonstrate that there is great potential for the production of functional materials with high overheating protection efficiency.

  3. Inorganic nanotubes reinforced polyvinylidene fluoride composites as low-cost electromagnetic interference shielding materials

    Directory of Open Access Journals (Sweden)

    Sankaranarayanan Venkataraman


    Full Text Available Abstract Novel polymer nanocomposites comprising of MnO2 nanotubes (MNTs, functionalized multiwalled carbon nanotubes (f-MWCNTs, and polyvinylidene fluoride (PVDF were synthesized. Homogeneous distribution of f-MWCNTs and MNTs in PVDF matrix were confirmed by field emission scanning electron microscopy. Electrical conductivity measurements were performed on these polymer composites using four probe technique. The addition of 2 wt.% of MNTs (2 wt.%, f-MWCNTs to PVDF matrix results in an increase in the electrical conductivity from 10-16S/m to 4.5 × 10-5S/m (3.2 × 10-1S/m. Electromagnetic interference shielding effectiveness (EMI SE was measured with vector network analyzer using waveguide sample holder in X-band frequency range. EMI SE of approximately 20 dB has been obtained with the addition of 5 wt.% MNTs-1 wt.% f-MWCNTs to PVDF in comparison with EMI SE of approximately 18 dB for 7 wt.% of f-MWCNTs indicating the potential use of the present MNT/f-MWCNT/PVDF composite as low-cost EMI shielding materials in X-band region.

  4. Fe-based bulk metallic glasses used for magnetic shielding (United States)

    Şerban, Va; Codrean, C.; Uţu, D.; Ercuţa, A.


    The casting in complex shapes (tubullar) and the main magnetic properties of bulk metallic glasses (BMG) alloys from the ferromagnetic Fe-Cr-Ni-Ga-P-Si-C system, with a small adittion of Ni (3%) were studied. Samples as rods and sockets having the thickness up to 1 mm were obtained from master alloys by melt injection by low cooling rates into a Cu mold and annealed in order to ensure adequate magnetic requirements. The structure was examined by X-ray diffraction (XRD) and the basic magnetic properties (coercivity, magnetic remanence, initial susceptibility, etc.) were determined by conventional low frequency induction method. The experimental investigations on producing of BMG ferromagnetic alloys with 3% Ni show the possibility to obtain magnetic shields of complex shape with satisfactory magnetic properties. The presence of Ni does not affect the glass forming ability, but reduce the shielding capacity.

  5. Optimized design on multi-layer iron fiber electromagnetic shielding materials%铁纤维多层电磁屏蔽材料优化设计

    Institute of Scientific and Technical Information of China (English)

    曲兆明; 王庆国; 秦思良; 胡小锋


    The relationship between shielding effectiveness of iron fiber multi-layer electromagnetic shielding materials and dimension, concentration of filler and thickness of each layer was presented based on strong fluctuation theory and electromagnetic field theory. Three-layer iron fiber composite was optimized using genetic algorithms from 8GHz to 12GHz and the optimization parameters of every layer were presented under the targets of shielding effectiveness not below 35dB and the total thickness not exceeding 5mm. The feasibility of design on broadband, thin-layer iron fiber electromagnetic shielding materials was verified by the example.%应用强扰动理论及电磁场理论建立了填充铁纤维多层电磁屏蔽材料屏蔽效能与填料尺寸、浓度及各层厚度的关系.基于遗传算法对频带8~18GHz内填充铁纤维三层屏蔽复合材料进行了优化设计,在屏蔽效能不小于35dB、总厚度不超过5mm的优化目标下,得到了各层材料的最佳结构参数配比.算例分析验证了填充铁纤维实现宽带薄层电磁屏蔽材料的可行性.

  6. Radiation Engineering Analysis of Shielding Materials to Assess Their Ability to Protect Astronauts in Deep Space From Energetic Particle Radiation (United States)

    Singleterry, R. C.


    An analysis is performed on four typical materials (aluminum, liquid hydrogen, polyethylene, and water) to assess their impact on the length of time an astronaut can stay in deep space and not exceed a design basis radiation exposure of 150 mSv. A large number of heavy lift launches of pure shielding mass are needed to enable long duration, deep space missions to keep astronauts at or below the exposure value with shielding provided by the vehicle. Therefore, vehicle mass using the assumptions in the paper cannot be the sole shielding mechanism for long duration, deep space missions. As an example, to enable the Mars Design Reference Mission 5.0 with a 400 day transit to and from Mars, not including the 500 day stay on the surface, a minimum of 24 heavy lift launches of polyethylene at 89,375 lbm (40.54 tonnes) each are needed for the 1977 galactic cosmic ray environment. With the assumptions used in this paper, a single heavy lift launch of water or polyethylene can protect astronauts for a 130 day mission before exceeding the exposure value. Liquid hydrogen can only protect the astronauts for 160 days. Even a single launch of pure shielding material cannot protect an astronaut in deep space for more than 180 days using the assumptions adopted in the analysis. It is shown that liquid hydrogen is not the best shielding material for the same mass as polyethylene for missions that last longer than 225 days.

  7. Detecting Shielded Special Nuclear Materials Using Multi-Dimensional Neutron Source and Detector Geometries (United States)

    Santarius, John; Navarro, Marcos; Michalak, Matthew; Fancher, Aaron; Kulcinski, Gerald; Bonomo, Richard


    A newly initiated research project will be described that investigates methods for detecting shielded special nuclear materials by combining multi-dimensional neutron sources, forward/adjoint calculations modeling neutron and gamma transport, and sparse data analysis of detector signals. The key tasks for this project are: (1) developing a radiation transport capability for use in optimizing adaptive-geometry, inertial-electrostatic confinement (IEC) neutron source/detector configurations for neutron pulses distributed in space and/or phased in time; (2) creating distributed-geometry, gas-target, IEC fusion neutron sources; (3) applying sparse data and noise reduction algorithms, such as principal component analysis (PCA) and wavelet transform analysis, to enhance detection fidelity; and (4) educating graduate and undergraduate students. Funded by DHS DNDO Project 2015-DN-077-ARI095.

  8. Detection of fast neutrons from shielded nuclear materials using a semiconductor alpha detector. (United States)

    Pöllänen, R; Siiskonen, T


    The response of a semiconductor alpha detector to fast (>1 MeV) neutrons was investigated by using measurements and simulations. A polyethylene converter was placed in front of the detector to register recoil protons generated by elastic collisions between neutrons and hydrogen nuclei of the converter. The developed prototype equipment was tested with shielded radiation sources. The low background of the detector and insensitivity to high-energy gamma rays above 1 MeV are advantages when the detection of neutron-emitting nuclear materials is of importance. In the case of a (252)Cf neutron spectrum, the intrinsic efficiency of fast neutron detection was determined to be 2.5×10(-4), whereas three-fold greater efficiency was obtained for a (241)AmBe neutron spectrum.

  9. Shield construction methods. Recent status and examples of development of material transportation systems; Shirudo koho. Saikin no shizai hanso system kaihatsu genkyo to jirei

    Energy Technology Data Exchange (ETDEWEB)

    Mochizuki, M.; Tazaki, A.; Makigami, S. [Tomoe Electric Manufacturing Company, Limited, Tokyo (Japan)


    Material transportation in a shield construction is assigned to transporting segments, aggregates, and pipes, particularly the segment transportation being the major assignment. Other materials are transported in spare moments between the segment transportation as required. The other materials can often be transported by utilizing segment transporting vehicles. Thus, for a transportation system in the shield construction, a segment transportation system which can synchronize with construction cycles based on those for a shield excavation machine is considered most importantly, and developed as the main force. The segment transportation system is classified into a rail type transportation system and a tire type transportation system. A high-speed transportation system of the former type transports materials at as high speed as 8 to 15 km/h. An Abt-system railway type steep-slope transportation system operates on slopes as steep as 20 to 40%. The tire transportation system is advantageous from an environmental preservation viewpoint. This paper introduces examples of constructions using a high-speed construction system for long tunnel construction, a steep-slope material transportation system, and an automatic trackless system. 2 figs., 2 tabs.

  10. Woven Thermal Protection System Based Heat-shield for Extreme Entry Environments Technology (HEEET) (United States)

    Ellerby, Donald; Venkatapathy, Ethiraj; Stackpoole, Margaret; Chinnapongse, Ronald; Munk, Michelle; Dillman, Robert; Feldman, Jay; Prabhu, Dinesh; Beerman, Adam


    NASA's future robotic missions utilizing an entry system into Venus and the outer planets, namely, Saturn, Uranus, Neptune, result in extremely high entry conditions that exceed the capabilities of state of the art low to mid density ablators such as PICA or Avcoat. Therefore mission planners typically assume the use of a fully dense carbon phenolic heat shield similar to what was flown on Pioneer Venus and Galileo. Carbon phenolic is a robust TPS material however its high density and relatively high thermal conductivity constrain mission planners to steep entries, with high heat fluxes and pressures and short entry durations, in order for CP to be feasible from a mass perspective. The high entry conditions pose challenges for certification in existing ground based test facilities and the longer-term sustainability of CP will continue to pose challenges. In 2012 the Game Changing Development Program (GCDP) in NASA's Space Technology Mission Directorate funded NASA ARC to investigate the feasibility of a Woven Thermal Protection System (WTPS) to meet the needs of NASA's most challenging entry missions. This project was highly successful demonstrating that a Woven TPS solution compares favorably to CP in performance in simulated reentry environments and provides the opportunity to manufacture graded materials that should result in overall reduced mass solutions and enable a much broader set of missions than does CP. Building off the success of the WTPS project GCDP has funded a follow on project to further mature and scale up the WTPS concept for insertion into future NASA robotic missions. The matured WTPS will address the CP concerns associated with ground based test limitations and sustainability. This presentation will briefly discuss results from the WTPS Project and the plans for WTPS maturation into a heat-shield for extreme entry environment.

  11. Prediction of Thermophysical and Thermomechanical Characteristics of Porous Carbon-Ceramic Composite Materials of the Heat Shield of Aerospace Craft (United States)

    Reznik, S. V.; Prosuntsov, P. V.; Mikhailovskii, K. V.


    A procedure for predicting thermophysical and thermomechanical characteristics of porous carbon-ceramic composite materials of the heat shield of aerospace craft as functions of the type of reinforcement, porosity of the structure, and the characteristics of the material's components has been developed. Results of mathematical modeling of the temperature and stressed-strained states of representative volume elements for determining the characteristics of a carbon-ceramic composite material with account taken of its anisotropy have been given.

  12. Study on γ-ray exposure buildup factors and fast neutron-shielding properties of some building materials (United States)

    Singh, Vishwanath P.; Badiger, N. M.; El-Khayatt, A. M.


    We have computed γ-ray exposure buildup factors (EBF) of some building materials; glass, marble, flyash, cement, limestone, brick, plaster of paris (POP) and gypsum for energy 0.015-15 MeV up to 40 mfp (mfp, mean free path) penetration depth. Also, the macroscopic effective removal cross-sections (ΣR) for fast neutron were calculated. We discussed the dependency of EBF values on photon energy, penetration depth and chemical elements. The half-value layer and kinetic energy per unit mass relative to air of building materials were calculated for assessment of shielding effectiveness. Shielding thicknesses for glass, marble, flyash, cement, limestone and gypsum plaster (or Plaster of Paris, POP) were found comparable with ordinary concrete. Among the studied materials limestone and POP showed superior shielding properties for γ-ray and neutron, respectively. Radiation safety inside houses, schools and primary health centers for sheltering and annual dose can be assessed by the determination of shielding parameters of common building materials.

  13. Characterization of Candidate Materials for Remote Recession Measurements of Ablative Heat Shield Materials (United States)

    Butler, Bradley D.; Winter, Michael; Panerai, Francesco; Martin, Alexandre; Bailey, Sean C. C.; Stackpoole, Margaret; Danehy, Paul M.; Splinter, Scott


    A method of remotely measuring surface recession of a material sample in a plasma flow through emission spectroscopy of the post shock layer was characterized through experiments in the NASA Langley HYMETS arc jet facility. Different methods for delivering the seed products into the Phenolic Impregnated Carbon Ablator (PICA) material samples were investigated. Three samples were produced by seeding the PICA material with combinations of Al, Si, HfO2, VB2, Al2O3, SiO2, TiC, HfC, NaCl, and MgCl2 through infusing seed materials into a core of PICA, or through encapsulating seed material in an epoxy disk, mechanically bonding the disk to a PICA sample. The PICA samples seeded with the candidate tracers were then tested at surface temperatures near 2400 K under low pressure air plasma. The emission of Al, Ti, V, Na, and Mg in the post-shock layer was observed in the UV with a high resolution imaging spectrometer viewing the whole stagnation line from the side, and from UV to NIR with a fiber-coupled miniaturized spectrometer observing the sample surface in the wavelength range from 200 nm to 1,100 nm from the front through a collimator. Al, Na, and Mg were found to be emitting in the post-shock spectra even before the recession reached the seeding depth - therefore possibly characterizing the pyrolysis process rather than the recession itself. The appearance of Ti and V emission in the spectra was well correlated with the actual recession which was monitored through a video of the front surface of the sample. The applicability of a seed material as an indicator for recession appears to be related to the melting temperature of the seed material. Future parametric studies will be carried out in low power plasma facilities at the University of Kentucky.

  14. Prediction of melanoma metastasis by the Shields index based on lymphatic vessel density

    Directory of Open Access Journals (Sweden)

    Metcalfe Chris


    Full Text Available Abstract Background Melanoma usually presents as an initial skin lesion without evidence of metastasis. A significant proportion of patients develop subsequent local, regional or distant metastasis, sometimes many years after the initial lesion was removed. The current most effective staging method to identify early regional metastasis is sentinel lymph node biopsy (SLNB, which is invasive, not without morbidity and, while improving staging, may not improve overall survival. Lymphatic density, Breslow's thickness and the presence or absence of lymphatic invasion combined has been proposed to be a prognostic index of metastasis, by Shields et al in a patient group. Methods Here we undertook a retrospective analysis of 102 malignant melanomas from patients with more than five years follow-up to evaluate the Shields' index and compare with existing indicators. Results The Shields' index accurately predicted outcome in 90% of patients with metastases and 84% without metastases. For these, the Shields index was more predictive than thickness or lymphatic density. Alternate lymphatic measurement (hot spot analysis was also effective when combined into the Shields index in a cohort of 24 patients. Conclusions These results show the Shields index, a non-invasive analysis based on immunohistochemistry of lymphatics surrounding primary lesions that can accurately predict outcome, is a simple, useful prognostic tool in malignant melanoma.

  15. Fast Neutron Tomography of Low-Z Object in High-Z Material Shielding (United States)

    Babai, Ruth Weiss; Sabo-Napadensky, Iris; Bar, Doron; Mor, Ilan; Tamim, Noam; Dangendorf, Volker; Tittelmeier, Kai; Bromberger, Benjamin; Weierganz, Mathias

    The technique and first results of Fast Neutron Tomography (FNCT) experiments are presented which are performed at the accelerator facility of PTB, Germany. A high-intensity neutron beam of broad spectral distribution with an average energy of 5.5 MeV, was produced by 11.5 MeV deuterons impinging upon a thick beryllium target. The capability of FNCT for high contrast imaging of low-Z materials embedded in thick high-Z shielding materials is demonstrated, which is superior to more conventional high-energy X-ray imaging techniques. For demonstrating the method special test objects were prepared: One consisted of an assembled polyethylene cylinder with holes of various diameters and directions drilled in its surface and inner parts. The plastic phantom was inserted into lead cylinders of different thicknesses. The detector system consisted of a plastic scintillator along with a dedicated optics, image-intensifier and a CCD camera. Two scintillator screens were compared: a bulk plastic scintillator screen and a fibres optical scintillator screen. The tomographic scans were taken in two geometrical configurations: cone beam and semi-fan beam configuration. The image quality favours the semi-fan beam configuration which on the other hand is more time consuming The obtained tomographic images and a comparison of the imaging quality between the different experimental conditions will be presented.

  16. A captured asteroid : Our David's stone for shielding earth and providing the cheapest extraterrestrial material (United States)

    Massonnet, Didier; Meyssignac, Benoît


    The issue of protecting the Earth against an asteroid impact is very popular and many concepts have been proposed to fulfil this objective. In this paper, we develop the idea of capturing a small size asteroid from an orbit close to Earth's in terms of energy and placing it into a loose Earth-bound orbit in order to use it as a shield by engineering its collision with any incoming, threatening body prior to its impact with the Earth. The operations for turning the captured asteroid into an efficient shield appear to be quicker, easier, cheaper and safer than an mission aimed at landing on an incoming impact-bound asteroid either for altering its trajectory or attempting to destroy it. The aim is an asteroid typically 20 40 m in diameter, too small to cause damage on Earth if an improper management leads to its crash, but big enough to destroy and deviate any incoming body if a collision is engineered with it preferably at more than one million km from Earth. Such a collision could be implemented within a 8 month time frame. Such an asteroid would also be a source of material such as liquid oxygen for exploratory missions. We show that the production of this material is much more efficient from an asteroid's surface than from the Moon's. As the celestial surface most accessible from Earth, a captured asteroid is also easier to engineer. Several thousands of tons of oxygen might become available sitting on the outer rim of Earth's gravity field. We examine the advantages and drawbacks of this concept and we propose a stepped approach for making it a reality within a foreseeable future. Key factors are first the detection of a candidate, whose small size make it difficult to spot, among a population of asteroids easy to reach from the Earth. We have identified such a potential candidate in 2000SG344 and describe the parameters of its capture. The second key point is how to deviate the candidate into an loose Earth bound orbit. Our preferred concept is to deposit a

  17. Radiation Shielding Properties Comparison of Pb-Based Silicate, Borate, and Phosphate Glass Matrices

    Directory of Open Access Journals (Sweden)

    Suwimon Ruengsri


    Full Text Available Theoretical calculations of mass attenuation coefficients, partial interactions, atomic cross-section, and effective atomic numbers of PbO-based silicate, borate, and phosphate glass systems have been investigated at 662 keV. PbO-based silicate glass has been found with the highest total mass attenuation coefficient and then phosphate and borate glasses, respectively. Compton scattering has been the dominate interaction contributed to the different total attenuation coefficients in each of the glass matrices. The silicate and phosphate glass systems are more appropriate choices as lead-based radiation shielding glass than the borate glass system. Moreover, comparison of results has shown that the glasses possess better shielding properties than standard shielding concretes, suggesting a smaller size requirement in addition to transparency in the visible region.

  18. Material characterisation and preliminary mechanical design for the HL-LHC shielded beam screens operating at cryogenic temperatures. (United States)

    Garion, C.; Dufay-Chanat, L.; Koettig, T.; Machiocha, W.; Morrone, M.


    The High Luminosity LHC project (HL-LHC) aims at increasing the luminosity (rate of collisions) in the Large Hadron Collider (LHC) experiments by a factor of 10 beyond the original design value (from 300 to 3000 fb-1). It relies on new superconducting magnets, installed close to the interaction points, equipped with new beam screen. This component has to ensure the vacuum performance together with shielding the cold mass from physics debris and screening the cold bore cryogenic system from beam induced heating. The beam screen operates in the range 40-60 K whereas the magnet cold bore temperature is 1.9 K. A tungsten-based material is used to absorb the energy of particles. In this paper, measurements of the mechanical and physical properties of such tungsten material are shown at room and cryogenic temperature. In addition, the design and the thermal mechanical behaviour of the beam screen assembly are presented also. They include the heat transfer from the tungsten absorbers to the cooling pipes and the supporting system that has to minimise the heat inleak into the cold mass. The behaviour during a magnet quench is also presented.

  19. Material characterisation and preliminary mechanical design for the HL-LHC shielded beam screens operating at cryogenic temperatures

    CERN Document Server

    Garion, C; Koettig, T; Machiocha, W; Morrone, M


    The High Luminosity LHC project (HL-LHC) aims at increasing the luminosity (rate of collisions) in the Large Hadron Collider (LHC) experiments by a factor of 10 beyond the original design value (from 300 to 3000 fb-1). It relies on new superconducting magnets, installed close to the interaction points, equipped with new beam screen. This component has to ensure the vacuum performance together with shielding the cold mass from physics debris and screening the cold bore cryogenic system from beam induced heating. The beam screen operates in the range 40-60 K whereas the magnet cold bore temperature is 1.9 K. A tungsten-based material is used to absorb the energy of particles. In this paper, measurements of the mechanical and physical properties of such tungsten material are shown at room and cryogenic temperature. In addition, the design and the thermal mechanical behaviour of the beam screen assembly are presented also. They include the heat transfer from the tungsten absorbers to the cooling pipes and the sup...

  20. A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, Gabriela [Pontificia Univ. Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil). Grupo de Experimentacao e Simulacao Computacional em Fisica Medica; Costa, Paulo Roberto, E-mail: [Universidade de Sao Paulo (IF/USP), SP (Brazil). Dept. de Fisica Nuclear. Lab. de Dosimetria das Radiacoes e Fisica Medica


    The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and compared to The American Association of Physicists in Medicine (AAPM) data for lead. Their influence on the transmission curves as well the study of the influence of the shielding material composition and beam geometry on the outgoing spectra were performed. Characteristics of transmitted spectra, such as shape, average energy and Half-Value Layer (HVL), were also evaluated. The Geant4 toolkit benchmark for the energy resulting from the positron annihilation phenomena and its application in transmission curves description shown good agreement between data published by American Association on Physicists in Medicine task group 108 and experimental data published by Brazil. The transmission properties for different material compositions were also studied and have shown low dependency with the considered thicknesses. The broad and narrow beams configuration presented significant differences on the result. The fitting parameter for determining the transmission curves equations, according to Archer model is presented for different material. As conclusion were defined that beam geometry has significant influence and the composition has low influence on transmission curves for shielding design for the range of energy applied to PET. (author)

  1. SU-E-T-523: Investigation of Various MR-Compatible Shielding Materials for Direction Modulated Brachytherapy (DMBT) Tandem Applicator for Cervical Cancer Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Safigholi, H; Soliman, A; Song, W [Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, U of T, Toronto, Ontario (Canada); Han, D [Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, U of T, Toronto, Ontario (Canada); University of California, San Diego, La Jolla, CA (United States); Meigooni, A Soleimani [Comprehensive Cancer Center of Nevada, Las Vegas, NV (United States); Scanderbeg, D [UCSD Medical Center, La Jolla, CA (United States)


    Purpose: To evaluate various shielding materials such as Gold (Au), Osmium (Os), Tantalum (Ta), and Tungsten (W) based alloys for use with a novel intensity modulation capable direction modulated brachytherapy (DMBT) tandem applicator for image guided cervical cancer HDR brachytherapy. Methods: The novel MRI-compatible DMBT tandem, made from nonmagnetic tungsten-alloy rod with diameter of 5.4 mm, has 6 symmetric peripheral holes of 1.3 mm diameter with 2.05 mm distance from the center for a high degree intensity modulation capacity. The 0.3 mm thickness of bio-compatible plastic tubing wraps the tandem. MCNPX was used for Monte Carlo simulations of the shields and the mHDR Ir-192 V2 source. MC-generated 3D dose matrices of different shielding materials of Au, Os, Ta, and W with 1 mm3 resolution were imported into an in-house-coded inverse optimization planning system to evaluate 19 clinical patient plans. Prescription dose was 15Gy. All plans were normalized to receive the same HRCTV D90. Results: In general, the plan qualities for various shielding materials were similar. The OAR D2cc for bladder was very similar for Au, Os, and Ta with 11.64±2.30Gy. For W, it was very close 11.65±2.30Gy. The sigmoid D2cc was 9.82±2.46Gy for Au and Os while it was 9.84±2.48Gy for Ta and W. The rectum D2cc was 7.44±3.06Gy for Au, 7.43±3.07Gy for Os, 7.48±3.05Gy for Ta, and 7.47±3.05Gy for W. The HRCTV D98 and V100 were very close with 16.37±1.87 Gy and 97.37±1.93 Gy, on average, respectively. Conclusion: Various MRI-compatible shielding alloys were investigated for the DMBT tandem applicator. The clinical plan qualities were not significantly different among these various alloys, however. Therefore, the candidate metals (or in combination) can be used to select best alloys for MRI image guided cervical cancer brachytherapy using the novel DMBT applicator that is capable of unprecedented level of intensity modulation.

  2. A Monte Carlo-based radiation safety assessment for astronauts in an environment with confined magnetic field shielding. (United States)

    Geng, Changran; Tang, Xiaobin; Gong, Chunhui; Guan, Fada; Johns, Jesse; Shu, Diyun; Chen, Da


    The active shielding technique has great potential for radiation protection in space exploration because it has the advantage of a significant mass saving compared with the passive shielding technique. This paper demonstrates a Monte Carlo-based approach to evaluating the shielding effectiveness of the active shielding technique using confined magnetic fields (CMFs). The International Commission on Radiological Protection reference anthropomorphic phantom, as well as the toroidal CMF, was modeled using the Monte Carlo toolkit Geant4. The penetrating primary particle fluence, organ-specific dose equivalent, and male effective dose were calculated for particles in galactic cosmic radiation (GCR) and solar particle events (SPEs). Results show that the SPE protons can be easily shielded against, even almost completely deflected, by the toroidal magnetic field. GCR particles can also be more effectively shielded against by increasing the magnetic field strength. Our results also show that the introduction of a structural Al wall in the CMF did not provide additional shielding for GCR; in fact it can weaken the total shielding effect of the CMF. This study demonstrated the feasibility of accurately determining the radiation field inside the environment and evaluating the organ dose equivalents for astronauts under active shielding using the CMF.

  3. Radiation shielding evaluation based on five years of data from a busy CyberKnife center. (United States)

    Yang, Jun; Feng, Jing


    We examined the adequacy of existing shielding guidelines using five-year clinical data from a busy CyberKnife center. From June 2006 through July 2011, 1,370 patients were treated with a total of 4,900 fractions and 680,691 radiation beams using a G4 CyberKnife. Prescription dose and total monitor units (MU) were analyzed to estimate the shielding workload and modulation factor. In addition, based on the beam's radiation source position, targeting position, MU, and beam collimator size, the MATLAB program was used to project each beam toward the shielding barrier. The summation of the projections evaluates the distribution of the shielding load. On average, each patient received 3.6 fractions, with an average 9.1 Gy per fraction prescribed at the 71.1% isodose line, using 133.7 beams and 6,200 MU. Intracranial patients received an average of 2.7 fractions, with 8.6 Gy per fraction prescribed at the 71.4% isodose line, using 133 beams and 5,083 MU. Extracranial patients received an average of 3.94 fractions, with 9.2 Gy per frac- tion prescribed at the 71% isodose line, using 134 beams and 6,514 MU. Most- used collimator sizes for intracranial patients were smaller (7.5 to 20 mm) than for extracranial patients (20 to 40 mm). Eighty-five percent of the beams exited through the floor, and about 40% of the surrounding wall area received no direct beam. For the rest of the wall, we found "hot" areas that received above-average MU. The locations of these areas were correlated with the projection of the nodes for extracranial treatments. In comparison, the beam projections on the wall were more spread for intracranial treatments. The maximum MU any area received from intracranial treatment was less than 0.25% of total MU used for intracranial treatments, and was less than 1.2% of total MU used for extracranial treatments. The combination of workload, modulation factor, and use factor in our practice are about tenfold less than recommendations in the existing Cyber

  4. Study on the Gamma Passive Analysis for the Thickness of Two Layer Shield Materials%双层屏蔽厚度γ反解技术研究

    Institute of Scientific and Technical Information of China (English)

    张连平; 吴伦强; 韦孟伏


    分析高分辨(能谱获取测量对象特定信息在军控核查领域有重要应用,根据多组不同能峰强度比等信息反解给出源外屏蔽材料几何信息有望有效消除未知包装容器对容器内部材料特性认识的影响。分析建立了反解源外双层屏蔽厚度的方法,实验测量反解了钚源和152 Eu点源外双层屏蔽材料的厚度,152 Eu点源的解析结果明显优于钚源,分析了实验解析结果与实际厚度值之间存在一定偏差的原因。%Acquiring the special information about measured object by gamma spectrum has important application in the field of arms control verification.The geometry information of the shield material out of source has been obtained by several group of intensity ratio of different energy gamma rays, which would reduce the affect for the evaluation of the inner assembly characteristic when the packaging is unknown.In this paper, the method of an-alyzing the thickness of several layers shield materials has been established, and the thickness of several layer shield materials out of plutonium source and 152 Eu source has been analyzed based on the experiment, the result of the 152 Eu source is better than the plutonium source obviously, the reason of the disagreement between the ex-periment result and the actual value has been analyzed.

  5. Microwave Absorption and Shielding, Property of Composites with FeSiA1 and Carbonous Materials as Filler

    Institute of Scientific and Technical Information of China (English)

    Wenqiang Zhang; Yonggang Xu; Liming Yuan; Jun Cai; Deyuan Zhangt


    Silicone rubber composites filled with FeSiAI alloys and multi-walled carbon nanotubes (MWCNT)/graphite have been prepared for the first time by a coating process. The complex permittivity and permeability of the composites were measured with a vector network analyzer in a 1-4 GHz frequency range, and the DC electric conductivity was measured by a standard four-point contact method. These parameters were then used to calculate the reflection loss (RL) and shielding effectiveness (SE) of the composites. The results showed that the added MWCNT increased the permittivity and permeability of composites in the L-band, while the added graphite increased only the permittivity. The variation lies in the interactions between two carbonous absorbents. Addition of 1 wt% MWCNT enhanced the RL in the L-band (minimum -5.7 dB at 1 ram, -7.3 dB at 1.5 ram), while the addition of graphite did not. Addition of MWCNT as well as graphite reinforced the shielding property of the composites (maximum SE 13.3 dB at 1 ram, 18.3 dB at 1.5 ram) owing to the increase of conductivity. The addition of these carbonous materials could hold the promise of enforcing the absorption and shielding property of the absorbers.

  6. Far Field Extrapolation from Near Field Interactions and Shielding Influence Investigations Based on a FE-PEEC Coupling Method

    Directory of Open Access Journals (Sweden)

    Gérard Meunier


    Full Text Available Regarding standards, it is well established that common mode currents are the main source of far field emitted by variable frequency drive (VFD-cable-motor associations. These currents are generated by the combination of floating potentials with stray capacitances between these floating potential tracks and the mechanical parts connected to the earth (the heatsink or cables are usual examples. Nowadays, due to frequency and power increases, the systematic compliance to EMC (ElectroMagnetic Compatibility becomes increasingly difficult and costly for industrials. As a consequence, there is a well-identified need to investigate practical and low cost solutions to reduce the radiated fields of VFD-cable-motor associations. A well-adapted solution is the shielding of wound components well known as the major source of near magnetic field. However, this solution is not convenient, it is expensive and may not be efficient regarding far field reduction. Optimizing the components placement could be a better and cheaper solution. As a consequence, dedicated tools have to be developed to efficiently investigate not easy comprehendible phenomena and finally to control EMC disturbances using component placement, layout geometry, shielding design if needed. However, none of the modeling methods usually used in industry complies with large frequency range and far field models including magnetic materials, multilayer PCBs, and shielding. The contribution of this paper is to show that alternatives regarding modeling solutions exist and can be used to get in-deep analysis of such complex structures. It is shown in this paper that near field investigations can give information on far field behavior. It is illustrated by an investigation of near field interactions and shielding influence using a FE-PEEC hybrid method. The test case combining a common mode filter with the floating potentials tracks of an inverter is based on an industrial and commercialized VFD. The

  7. Radiation transmission data for radionuclides and materials relevant to brachytherapy facility shielding. (United States)

    Papagiannis, P; Baltas, D; Granero, D; Pérez-Calatayud, J; Gimeno, J; Ballester, F; Venselaar, J L M


    To address the limited availability of radiation shielding data for brachytherapy as well as some disparity in existing data, Monte Carlo simulation was used to generate radiation transmission data for 60Co, 137CS, 198Au, 192Ir 169Yb, 170Tm, 131Cs, 125I, and 103pd photons through concrete, stainless steel, lead, as well as lead glass and baryte concrete. Results accounting for the oblique incidence of radiation to the barrier, spectral variation with barrier thickness, and broad beam conditions in a realistic geometry are compared to corresponding data in the literature in terms of the half value layer (HVL) and tenth value layer (TVL) indices. It is also shown that radiation shielding calculations using HVL or TVL values could overestimate or underestimate the barrier thickness required to achieve a certain reduction in radiation transmission. This questions the use of HVL or TVL indices instead of the actual transmission data. Therefore, a three-parameter model is fitted to results of this work to facilitate accurate and simple radiation shielding calculations.

  8. LDEF materials data bases (United States)

    Funk, Joan G.; Strickland, John W.; Davis, John M.


    The Long Duration Exposure Facility (LDEF) and the accompanying experiments were composed of and contained a wide variety of materials representing the largest collection of materials flown in low Earth orbit (LEO) and retrieved for ground based analysis to date. The results and implications of the mechanical, thermal, optical, and electrical data from these materials are the foundation on which future LEO space missions will be built. The LDEF Materials Special Investigation Group (MSIG) has been charged with establishing and developing data bases to document these materials and their performance to assure not only that the data are archived for future generations but also that the data are available to the spacecraft user community in an easily accessed, user-friendly form. This paper discusses the format and content of the three data bases developed or being developed to accomplish this task. The hardware and software requirements for each of these three data bases are discussed along with current availability of the data bases. This paper also serves as a user's guide to the MAPTIS LDEF Materials Data Base.

  9. Decomposition of the absorbed dose by LET in tissue-equivalent materials within the SHIELD-HIT transport code

    CERN Document Server

    Sobolevsky, N; Buyukcizmeci, N; Ergun, A; Latysheva, L; Ogul, R


    The SHIELD-HIT transport code, in several versions, has been used for modeling the interaction of therapeutic beams of light nuclei with tissue-equivalent materials for a long time. All versions of the code include useful option of decomposition of the absorbed dose by the linear energy transfer (LET), but this option has not been described and published so far. In this work the procedure of decomposition of the absorbed dose by LET is described and illustrated by using the decomposition of the Bragg curve in water phantom, irradiated by beams of protons, alpha particles, and of ions lithium, carbon and oxygen.

  10. Electromagnetic Wave Shielding Effectiveness Based on Carbon Microcoil-Polyurethane Composites

    Directory of Open Access Journals (Sweden)

    Gi-Hwan Kang


    Full Text Available Carbon microcoils (CMCs were deposited onto Al2O3 substrates using C2H2/H2 as source gases and SF6 as an incorporated additive gas in a thermal chemical vapor deposition system. CMC-polyurethane (PU composites were obtained by dispersing the CMCs in the PU with a dimethylformamide additive. The electromagnetic wave shielding properties of the CMC-PU composites were examined in the frequency range of 0.25–1.5 GHz. The shielding effectiveness (SE of the CMCs-PU systematically increases with increasing the content of CMCs and/or the layer thickness. Based on these results, the main SE mechanism for this work was suggested and discussed.

  11. Determination of total mass attenuation coefficients, effective atomic numbers and electron densities for different shielding materials used in radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Almeida J, A. T. [FUNDACENTRO, Centro Regional de Minas Gerais, Brazilian Institute for Safety and Health at Work, Belo Horizonte, 30180-100 Minas Gerais (Brazil); Nogueira, M. S. [Center of Development of Nuclear Technology / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Santos, M. A. P., E-mail: [Regional Center for Nuclear Science / CNEN, 50.740-540 Recife, Pernambuco (Brazil)


    Full text: In this paper, the interaction of X-rays with some shielding materials has been studied for materials containing different amounts of barite and aggregates. The total mass attenuation coefficient (μ{sub t}) for three shielding materials has been calculated by using WinXCOM program in the energy range from RQR qualities (RQR-4, RQR-6, RQR-9, and RQR-10). They were: cream barite (density 2.99 g/cm{sup 3} collected in the State of Sao Paulo), purple barite (density 2.95 g/cm{sup 3} collected in the State of Bahia) and white barite (density 3.10 g/cm{sup 3} collected in the State of Paraiba). The chemical analysis was carried out by an X-ray fluorescence spectrometer model EDX-720, through dispersive energy. The six elements of the higher concentration found in the sample and analyzed by Spectrophotometry of Energy Dispersive X-ray for the samples were Ba(60.9% - white barite), Ca(17,92% - cream barite), Ce(3,60% - white barite), Fe(17,16% - purple barite), S(12,11% - white barite) and Si(29,61% - purple barite). Also, the effective atomic number (Z{sub eff}) and the effective electron density (N{sub eff}) were calculated using the values of the total mass attenuation coefficient. The dependence of these parameters on the incident photon energy and the chemical composition has been examined. (Author)

  12. Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material

    Energy Technology Data Exchange (ETDEWEB)

    G. Gordon


    Stress corrosion cracking is one of the most common corrosion-related causes for premature breach of metal structural components. Stress corrosion cracking is the initiation and propagation of cracks in structural components due to three factors that must be present simultaneously: metallurgical susceptibility, critical environment, and static (or sustained) tensile stresses. This report was prepared according to ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The purpose of this report is to provide an evaluation of the potential for stress corrosion cracking of the engineered barrier system components (i.e., the drip shield, waste package outer barrier, and waste package stainless steel inner structural cylinder) under exposure conditions consistent with the repository during the regulatory period of 10,000 years after permanent closure. For the drip shield and waste package outer barrier, the critical environment is conservatively taken as any aqueous environment contacting the metal surfaces. Appendix B of this report describes the development of the SCC-relevant seismic crack density model (SCDM). The consequence of a stress corrosion cracking breach of the drip shield, the waste package outer barrier, or the stainless steel inner structural cylinder material is the initiation and propagation of tight, sometimes branching, cracks that might be induced by the combination of an aggressive environment and various tensile stresses that can develop in the drip shields or the waste packages. The Stainless Steel Type 316 inner structural cylinder of the waste package is excluded from the stress corrosion cracking evaluation because the Total System Performance Assessment for License Application (TSPA-LA) does not take credit for the inner cylinder. This document provides a detailed description of the process-level models that can be applied to assess the

  13. Shields-1, A SmallSat Radiation Shielding Technology Demonstration (United States)

    Thomsen, D. Laurence, III; Kim, Wousik; Cutler, James W.


    The NASA Langley Research Center Shields CubeSat initiative is to develop a configurable platform that would allow lower cost access to Space for materials durability experiments, and to foster a pathway for both emerging and commercial-off-the-shelf (COTS) radiation shielding technologies to gain spaceflight heritage in a relevant environment. The Shields-1 will be Langleys' first CubeSat platform to carry out this mission. Radiation shielding tests on Shields-1 are planned for the expected severe radiation environment in a geotransfer orbit (GTO), where advertised commercial rideshare opportunities and CubeSat missions exist, such as Exploration Mission 1 (EM-1). To meet this objective, atomic number (Z) graded radiation shields (Zshields) have been developed. The Z-shield properties have been estimated, using the Space Environment Information System (SPENVIS) radiation shielding computational modeling, to have 30% increased shielding effectiveness of electrons, at half the thickness of a corresponding single layer of aluminum. The Shields-1 research payload will be made with the Z-graded radiation shields of varying thicknesses to create dose-depth curves to be compared with baseline materials. Additionally, Shields-1 demonstrates an engineered Z-grade radiation shielding vault protecting the systems' electronic boards. The radiation shielding materials' performances will be characterized using total ionizing dose sensors. Completion of these experiments is expected to raise the technology readiness levels (TRLs) of the tested atomic number (Z) graded materials. The most significant contribution of the Z-shields for the SmallSat community will be that it enables cost effective shielding for small satellite systems, with significant volume constraints, while increasing the operational lifetime of ionizing radiation sensitive components. These results are anticipated to increase the development of CubeSat hardware design for increased mission lifetimes, and enable

  14. Shielding design and dose assessment for accelerator based neutron capture therapy. (United States)

    Howard, W B; Yanch, J C


    Preparations are ongoing to test the viability and usefulness of an accelerator source of epithermal neutrons for ultimate use in a clinical environment. This feasibility study is to be conducted in a shielded room located on the Massachusetts Institute of Technology campus and will not involve patient irradiations. The accelerator production of neutrons is based on the 7Li(p, n)7Be reaction, and a maximum proton beam current of 4 mA at an energy of 2.5 MeV is anticipated. The resultant 3.58 x 10(12) neutrons s-1 have a maximum energy of 800 keV and will be substantially moderated. This paper describes the Monte Carlo methods used to estimate the neutron and photon dose rates in a variety of locations in the vicinity of the accelerator, as well as the shielding configuration required when the device is run at maximum current. Results indicate that the highest absorbed dose rate to which any individual will be exposed is 3 microSv h-1 (0.3 mrem h-1). The highest possible yearly dose is 0.2 microSv (2 x 10(-2) mrem) to the general public or 0.9 mSv (90 mrem) to a radiation worker in close proximity to the accelerator facility. The shielding necessary to achieve these dose levels is also discussed.

  15. Optimization design of electromagnetic shielding composites (United States)

    Qu, Zhaoming; Wang, Qingguo; Qin, Siliang; Hu, Xiaofeng


    The effective electromagnetic parameters physical model of composites and prediction formulas of composites' shielding effectiveness and reflectivity were derived based on micromechanics, variational principle and electromagnetic wave transmission theory. The multi-objective optimization design of multilayer composites was carried out using genetic algorithm. The optimized results indicate that material parameter proportioning of biggest absorption ability can be acquired under the condition of the minimum shielding effectiveness can be satisfied in certain frequency band. The validity of optimization design model was verified and the scheme has certain theoretical value and directive significance to the design of high efficiency shielding composites.

  16. Research Progress of Electromagnetic Shielding Material of Metal Fiber%金属纤维电磁屏蔽材料的研究进展

    Institute of Scientific and Technical Information of China (English)

    王建忠; 奚正平; 汤慧萍; 黄卫东; 朱纪磊; 李程; 敖庆波


    The present paper describes briefly the harm of electromagnetic radiation and the mechanism of electromagnetic shielding material and it focuses on the application and research progress of electromagnetic shielding fabric, electromagnetic shielding polymer and electromagnetic shielding architecture and decoration material made by metal fiber and predicts the development of electromagnetic shielding material in the future. It points out that great attention should be paid to developing an advanced, high-property, low-consumption and green-environment-protection electromagnetic shielding materials with high absorption and low reflection and transmission. Furthermore, it considers that the internal composition and structure need optimizing and the forming process needs improving in order to enhance shielding effectiveness.%描述电磁辐射的危害及电磁屏蔽材料的屏蔽机制,重点阐述金属纤维制备电磁屏蔽织物、电磁屏蔽聚合物材料及电磁屏蔽建筑与装饰材料的应用及研究进展,并对未来电磁屏蔽材料的发展趋势作预测,指出开发具有高吸收率、低反射率与低透射率的高性能、低消耗兼绿色环保的新型电磁屏蔽材料是未来的研究重点,同时对材料内部组织与结构进行优化,改进成型工艺,提高其电磁屏蔽效能.

  17. Shield gas induced cracks during nanosecond-pulsed laser irradiation of Zr-based metallic glass (United States)

    Huang, Hu; Noguchi, Jun; Yan, Jiwang


    Laser processing techniques have been given increasing attentions in the field of metallic glasses (MGs). In this work, effects of two kinds of shield gases, nitrogen and argon, on nanosecond-pulsed laser irradiation of Zr-based MG were comparatively investigated. Results showed that compared to argon gas, nitrogen gas remarkably promoted the formation of cracks during laser irradiation. Furthermore, crack formation in nitrogen gas was enhanced by increasing the peak laser power intensity or decreasing the laser scanning speed. X-ray diffraction and micro-Raman spectroscopy indicated that the reason for enhanced cracks in nitrogen gas was the formation of ZrN.

  18. Review of the Lightning Shielding Against Direct Lightning Strokes Based on Laboratory Long Air Gap Discharges

    Institute of Scientific and Technical Information of China (English)


    It is one of the most effective ways to use laboratory long air gap discharges tbr investigating the fundamental process involved in the lightning strike. During the 1960s and the 1970s, the electro-geometrical method (EGM) and the rolling sphere method were developed base on the breakdown characteristics of negative long spark discharges, which have been widely used to design the lightning shielding system of transmission lines and structures. In recent years, the scale of the power facilities is increased dramatically with the rising of power grid's voltage level.

  19. Shield gas induced cracks during nanosecond-pulsed laser irradiation of Zr-based metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hu; Noguchi, Jun; Yan, Jiwang [Keio University, Department of Mechanical Engineering, Faculty of Science and Technology, Yokohama (Japan)


    Laser processing techniques have been given increasing attentions in the field of metallic glasses (MGs). In this work, effects of two kinds of shield gases, nitrogen and argon, on nanosecond-pulsed laser irradiation of Zr-based MG were comparatively investigated. Results showed that compared to argon gas, nitrogen gas remarkably promoted the formation of cracks during laser irradiation. Furthermore, crack formation in nitrogen gas was enhanced by increasing the peak laser power intensity or decreasing the laser scanning speed. X-ray diffraction and micro-Raman spectroscopy indicated that the reason for enhanced cracks in nitrogen gas was the formation of ZrN. (orig.)

  20. Neutronic Reactor Shield (United States)

    Fermi, Enrico; Zinn, Walter H.

    The argument of the present Patent is a radiation shield suitable for protection of personnel from both gamma rays and neutrons. Such a shield from dangerous radiations is achieved to the best by the combined action of a neutron slowing material (a moderator) and a neutron absorbing material. Hydrogen is particularly effective for this shield since it is a good absorber of slow neutrons and a good moderator of fast neutrons. The neutrons slowed down by hydrogen may, then, be absorbed by other materials such as boron, cadmium, gadolinium, samarium or steel. Steel is particularly convenient for the purpose, given its effectiveness in absorbing also the gamma rays from the reactor (both primary gamma rays and secondary ones produced by the moderation of neutrons). In particular, in the present Patent a shield is described, made of alternate layers of steel and Masonite (an hydrolized ligno-cellulose material). The object of the present Patent is not discussed in any other published paper.

  1. Foam-Reinforced Polymer Matrix Composite Radiation Shields Project (United States)

    National Aeronautics and Space Administration — New and innovative lightweight radiation shielding materials are needed to protect humans in future manned exploration vehicles. Radiation shielding materials are...

  2. Shielding from cosmic radiation for interplanetary missions Active and passive methods

    CERN Document Server

    Spillantini, P; Durante, M; Müller-Mellin, R; Reitz, G; Rossi, L; Shurshakov, V; Sorbi, M


    Shielding is arguably the main countermeasure for the exposure to cosmic radiation during interplanetary exploratory missions. However, shielding of cosmic rays, both of galactic or solar origin, is problematic, because of the high energy of the charged particles involved and the nuclear fragmentation occurring in shielding materials. Although computer codes can predict the shield performance in space, there is a lack of biological and physical measurements to benchmark the codes. An attractive alternative to passive, bulk material shielding is the use of electromagnetic fields to deflect the charged particles from the spacecraft target. Active shielding concepts based on electrostatic fields, plasma, or magnetic fields have been proposed in the past years, and should be revised based on recent technological improvements. To address these issues, the European Space Agency (ESA) established a Topical Team (TT) in 2002 including European experts in the field of space radiation shielding and superconducting magn...

  3. Space life sciences: ground-based iron-ion biology and physics, including shielding. (United States)


    This session of the 35th Scientific Assembly of COSPAR focuses on recent advances in ground-based studies of high-energy (mainly 1 GeV/nucleon) iron ions. The theme is interdisciplinary in nature and encompasses both physics and biology reports. Manned space missions, including those of the International Space Station and the planned Mars mission, will require the extended presence of crew members in space. As such, a better understanding in shielding design--in radiation detection as well as radio-protection based on simulating studies--is much needed. On the other hand, a better understanding of the basic mechanisms that modulate radiation sensitivity; in determining DNA double strand breaks, chromosomal aberrations, and the induction of apoptosis, will provide important information for an interventional approach.

  4. The evaluation of neutron and gamma ray dose equivalent distributions in patients and the effectiveness of shield materials for high energy photons radiotherapy facilities. (United States)

    Ghassoun, J; Senhou, N


    In this study, the MCNP5 code was used to model radiotherapy room of a medical linear accelerator operating at 18 MV and to evaluate the neutron and the secondary gamma ray fluences, the energy spectra and the dose equivalent distributions inside a liquid tissue-equivalent (TE) phantom. The obtained results were compared with measured data published in the literature. Moreover, the shielding effects of various neutron material shields on the radiotherapy room wall were also investigated. Our simulation results showed that paraffin wax containing boron carbide presents enough effectiveness to reduce both neutron and secondary gamma ray doses.

  5. The evaluation of neutron and gamma ray dose equivalent distributions in patients and the effectiveness of shield materials for high energy photons radiotherapy facilities

    Energy Technology Data Exchange (ETDEWEB)

    Ghassoun, J., E-mail: [EPRA, Department of Physics, Faculty of Sciences Semlalia, PO Box: 2390, 40000 Marrakech (Morocco); Senhou, N. [EPRA, Department of Physics, Faculty of Sciences Semlalia, PO Box: 2390, 40000 Marrakech (Morocco)


    In this study, the MCNP5 code was used to model radiotherapy room of a medical linear accelerator operating at 18 MV and to evaluate the neutron and the secondary gamma ray fluences, the energy spectra and the dose equivalent distributions inside a liquid tissue-equivalent (TE) phantom. The obtained results were compared with measured data published in the literature. Moreover, the shielding effects of various neutron material shields on the radiotherapy room wall were also investigated. Our simulation results showed that paraffin wax containing boron carbide presents enough effectiveness to reduce both neutron and secondary gamma ray doses. - Highlights: Black-Right-Pointing-Pointer The Monte Carlo method has been used to model radiotherapy room of a 18 MV linear accelerator. Black-Right-Pointing-Pointer The neutron and the gamma ray dose equivalent distributions inside a liquid (TE) phantom were evaluated. Black-Right-Pointing-Pointer The radiotherapy room shielding performance has been also investigated.

  6. Stress Corrosion Cracking of the Drip Shield, The Waste Package Outer Barrier and the Stainless Steel Structural Material

    Energy Technology Data Exchange (ETDEWEB)

    C. Stephen


    One of the potential failure modes of the drip shield (DS), the waste package (WP) outer barrier, and the stainless structural material is the initiation and propagation of stress corrosion cracking (SCC) induced by the WP environment and various types of stresses that can develop in the DSs or the WPs. For the current design of the DS and WP, however, the DS will be excluded from the SCC evaluation because stresses that are relevant to SCC are insignificant in the DS. The major sources of stresses in the DS are loadings due to backfill and earthquakes. These stresses will not induce SCC because the stress caused by backfill is generally compressive stress and the stress caused by earthquakes is temporary in nature. The 316NG stainless steel inner barrier of the WP will also be excluded from the SCC evaluation because the SCC performance assessment will not take credit from the inner barrier. Therefore, the purpose of this document is to provide a detailed description of the process-level models that can be applied to assess the performance of the material (i.e., Alloy 22) used for the WP outer barrier subjected to the effects of SCC. As already mentioned in the development plan for the WP PMR (CRWMS M and O 1999e), this Analyses and Models Report (AMR) is to serve as a feed to the Waste Package Degradation (WPD) Total System Performance Assessment (TSPA) and Process Model Report (PMR).

  7. Preparation of the New-type Gradient Nuclear Radiation Shielding Material%一种新型梯度防核辐射材料的制备

    Institute of Scientific and Technical Information of China (English)

    马涛; 刘宇艳; 刘振国; 刘少柱; 贾默; 尹松年


    A new-type gradient nuclear radiation shielding material was prepared for utilizing Lu203 ,tungsten and polyethylene as main raw materials by mechanical blending method handled with coupling agent, acid and alkali reaction method and in-situ reaction. Afterwards hot-press processing and layered hot-pressing superimposition was used to process materials and then gradient materials were obtained. At last,monolayer and gradient materials were characterized and tested. The results indicated that: the new gradient material had good tensile properties. Meanwhile, beta and gamma rays could be shielded well, it oneself had lead-free poison, the lasting shielding effectiveness, the good comprehensive shielding performance,and it could flexibly adjust the types and the order of monolayer materials for getting corresponding gradient materials according to the specific radiation environment. The gradient materials had a good application future.%以氧化镥、钨、聚乙烯为主要原料,运用偶联剂处理的机械共混法、酸碱反应法、原位反应法制备出一种新型梯度防核辐射材料,测试结果表明:制得的新型梯度防核辐射材料,具有良好的拉伸性能,对口射线、7射线均有很好的屏蔽效果,无铅毒、屏蔽效能持久,综合性能良好。这种梯度材料能根据具体辐射环境灵活调整组成材料的种类与顺序,具有良好的应用价值与使用前景。

  8. Absolute Position Sensing Based on a Robust Differential Capacitive Sensor with a Grounded Shield Window. (United States)

    Bai, Yang; Lu, Yunfeng; Hu, Pengcheng; Wang, Gang; Xu, Jinxin; Zeng, Tao; Li, Zhengkun; Zhang, Zhonghua; Tan, Jiubin


    A simple differential capacitive sensor is provided in this paper to measure the absolute positions of length measuring systems. By utilizing a shield window inside the differential capacitor, the measurement range and linearity range of the sensor can reach several millimeters. What is more interesting is that this differential capacitive sensor is only sensitive to one translational degree of freedom (DOF) movement, and immune to the vibration along the other two translational DOFs. In the experiment, we used a novel circuit based on an AC capacitance bridge to directly measure the differential capacitance value. The experimental result shows that this differential capacitive sensor has a sensitivity of 2 × 10(-4) pF/μm with 0.08 μm resolution. The measurement range of this differential capacitive sensor is 6 mm, and the linearity error are less than 0.01% over the whole absolute position measurement range.

  9. 隔声罩吸声材料对其性能影响研究%Research on the Influence of Acoustic Shield Absorption Material on Its Performance

    Institute of Scientific and Technical Information of China (English)

    冀军鹤; 唐鹏


    In order to improve the performance of acoustic shield in our company's compressor, with a screw compressor as testing machine, sound absorption material used for the acoustic shield is researched. The results show that designing available materials have great influence on performance of acoustic shield according to noise spectrum characteristics. The optimized sound absorption material has made the acoustic shield insertion loss improved by 4.4 dB (A), reaching expected requirements.%以某螺杆压缩机作为试验机,对其隔声罩所用吸声材料进行研究。结果表明,根据噪声源频谱特征、设计合适的吸声材料对隔声罩的性能改善至关重要。吸声材料优化使得隔声罩的性能插入损失提高4.4dB (A),符合预期要求。

  10. Reliability Methods for Shield Design Process (United States)

    Tripathi, R. K.; Wilson, J. W.


    Providing protection against the hazards of space radiation is a major challenge to the exploration and development of space. The great cost of added radiation shielding is a potential limiting factor in deep space operations. In this enabling technology, we have developed methods for optimized shield design over multi-segmented missions involving multiple work and living areas in the transport and duty phase of space missions. The total shield mass over all pieces of equipment and habitats is optimized subject to career dose and dose rate constraints. An important component of this technology is the estimation of two most commonly identified uncertainties in radiation shield design, the shielding properties of materials used and the understanding of the biological response of the astronaut to the radiation leaking through the materials into the living space. The largest uncertainty, of course, is in the biological response to especially high charge and energy (HZE) ions of the galactic cosmic rays. These uncertainties are blended with the optimization design procedure to formulate reliability-based methods for shield design processes. The details of the methods will be discussed.

  11. Radiation shielding design for neutron diffractometers assisted by Monte Carlo methods (United States)

    Osborn, John C.; Ersez, Tunay; Braoudakis, George


    Monte Carlo simulations may be used to model radiation shielding for neutron diffractometers. The use of the MCNP computer program to assess shielding for a diffractometer is discussed. A comparison is made of shielding requirements for radiation generated by several materials commonly used in neutron optical elements and beam stops, including lithium-6 based absorbers where the Monte Carlo method can model the effects of fast neutrons generated by this material.

  12. Shielding Design and Radiation Shielding Evaluation for LSDS System Facility

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Younggook; Kim, Jeongdong; Lee, Yongdeok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    As the system characteristics, the target in the spectrometer emits approximately 1012 neutrons/s. To efficiently shield the neutron, the shielding door designs are proposed for the LSDS system through a comparison of the direct shield and maze designs. Hence, to guarantee the radiation safety for the facility, the door design is a compulsory course of the development of the LSDS system. To improve the shielding rates, 250x250 covering structure was added as a subsidiary around the spectrometer. In this study, the evaluations of the suggested shielding designs were conducted using MCNP code. The suggested door design and covering structures can shield the neutron efficiently, thus all evaluations of all conditions are satisfied within the public dose limits. From the Monte Carlo code simulation, Resin(Indoor type) and Tungsten(Outdoor type) were selected as the shielding door materials. From a comparative evaluation of the door thickness, In and Out door thickness was selected 50 cm.

  13. Preparation and Study of Electromagnetic Interference Shielding Materials Comprised of Ni-Co Coated on Web-Like Biocarbon Nanofibers via Electroless Deposition

    Directory of Open Access Journals (Sweden)

    Xiaohu Huang


    Full Text Available Electromagnetic interference (EMI shielding materials made of Ni-Co coated on web-like biocarbon nanofibers were successfully prepared by electroless plating. Biocarbon nanofibers (CF with a novel web-like structure comprised of entangled and interconnected carbon nanoribbons were obtained using bacterial cellulose pyrolyzed at 1200°C. Paraffin wax matrix composites filled with different loadings (10, 20, and 30 wt%, resp. of CF and Ni-Co coated CF (NCCF were prepared. The electrical conductivities and electromagnetic parameters of the composites were investigated by the four-probe method and vector network analysis. From these results, the EMI shielding efficiencies (SE of NCCF composites were shown to be significantly higher than that of CF at the same mass fraction. The paraffin wax composites containing 30 wt% NCCF showed the highest EMI SE of 41.2 dB (99.99% attenuation, which are attributed to the higher electrical conductivity and permittivity of the NCCF composites than the CF composites. Additionally, EMI SE increased with an increase in CF and NCCF loading and the absorption was determined to be the primary factor governing EMI shielding. This study conclusively reveals that NCCF composites have potential applications as EMI shielding materials.

  14. The Development of Materials for Structures and Radiation Shielding in Aerospace (United States)

    Kiefer, Richard L.; Orwoll, Robert A.


    Polymeric materials on space vehicles and high-altitude aircraft win be exposed to highly penetrating radiations. These radiations come from solar flares and galactic cosmic rays (GCR). Radiation from solar flares consists primarily of protons with energies less than 1 GeV. On the other hand, GCR consist of nuclei with energies as high as 10(exp 10) GeV. Over 90% of the nuclei in GCR are protons and alpha particles, however there is a small but significant component of particles with atomic numbers greater than ten. Particles with high atomic number (Z) and high energy interact with very high specific ionization and thus represent a serious hazard for humans and electronic equipment on a spacecraft or on high-altitude commercial aircraft (most importantly for crew members who would have long exposures). Neutrons generated by reactions with the high energy particles also represent a hazard both for humans and electronic equipment.

  15. Mechanical, Electromagnetic, and X-ray Shielding Characterization of a 3D Printable Tungsten-Polycarbonate Polymer Matrix Composite for Space-Based Applications (United States)

    Shemelya, Corey M.; Rivera, Armando; Perez, Angel Torrado; Rocha, Carmen; Liang, Min; Yu, Xiaoju; Kief, Craig; Alexander, David; Stegeman, James; Xin, Hao; Wicker, Ryan B.; MacDonald, Eric; Roberson, David A.


    Material-extrusion three-dimensional (3D) printing has recently attracted much interest because of its process flexibility, rapid response to design alterations, and ability to create structures "on-the-go". For this reason, 3D printing has possible applications in rapid creation of space-based devices, for example cube satellites (CubeSat). This work focused on fabrication and characterization of tungsten-doped polycarbonate polymer matrix composites specifically designed for x-ray radiation-shielding applications. The polycarbonate-tungsten polymer composite obtained intentionally utilizes low loading levels to provide x-ray shielding while limiting effects on other properties of the material, for example weight, electromagnetic functionality, and mechanical strength. The fabrication process, from tungsten functionalization to filament extrusion and material characterization, is described, including printability, determination of x-ray attenuation, tensile strength, impact resistance, and gigahertz permittivity, and failure analysis. The proposed materials are uniquely advantageous when implemented in 3D printed structures, because even a small volume fraction of tungsten has been shown to substantially alter the properties of the resulting composite.

  16. High frequency electromagnetic interference shielding magnetic polymer nanocomposites (United States)

    He, Qingliang

    Electromagnetic interference is one of the most concerned pollution and problem right now since more and more electronic devices have been extensively utilized in our daily lives. Besides the interference, long time exposure to electromagnetic radiation may also result in severe damage to human body. In order to mitigate the undesirable part of the electromagnetic wave energy and maintain the long term sustainable development of our modern civilized society, new technology development based researches have been made to solve this problem. However, one of the major challenges facing to the electromagnetic interference shielding is the relatively low shielding efficiency and the high cost as well as the complicated shielding material manufacture. From the materials science point of view, the key solutions to these challenges are strongly depended on the breakthrough of the current limit of shielding material design and manufacture (such as hierarchical material design with controllable and predictable arrangement in nanoscale particle configuration via an easy in-situ manner). From the chemical engineering point of view, the upgrading of advanced material shielding performance and the enlarged production scale for shielding materials (for example, configure the effective components in the shielding material in order to lower their usage, eliminate the "rate-limiting" step to enlarge the production scale) are of great importance. In this dissertation, the design and preparation of morphology controlled magnetic nanoparticles and their reinforced polypropylene polymer nanocomposites will be covered first. Then, the functionalities of these polymer nanocomposites will be demonstrated. Based on the innovative materials design and synergistic effect on the performance advancement, the magnetic polypropylene polymer nanocomposites with desired multifunctionalities are designed and produced targeting to the electromagnetic interference shielding application. In addition

  17. A Launch Requirements Trade Study for Active Space Radiation Shielding for Long Duration Human Missions (United States)

    Singleterry, Robert C., Jr.; Bollweg, Ken; Martin, Trent; Westover, Shayne; Battiston, Roberto; Burger, William J.; Meinke, Rainer


    A trade study for an active shielding concept based on magnetic fields in a solenoid configuration versus mass based shielding was developed. Monte Carlo simulations were used to estimate the radiation exposure for two values of the magnetic field strength and the mass of the magnetic shield configuration. For each field strength, results were reported for the magnetic region shielding (end caps ignored) and total region shielding (end caps included but no magnetic field protection) configurations. A value of 15 cSv was chosen to be the maximum exposure for an astronaut. The radiation dose estimate over the total shield region configuration cannot be used at this time without a better understanding of the material and mass present in the end cap regions through a detailed vehicle design. The magnetic shield region configuration, assuming the end cap regions contribute zero exposure, can be launched on a single Space Launch System rocket and up to a two year mission can be supported. The magnetic shield region configuration results in two versus nine launches for a comparable mass based shielding configuration. The active shielding approach is clearly more mass efficient because of the reduced number of launches than the mass based shielding for long duration missions.

  18. Shielding Effectiveness of Composites Containing Flaky Inclusions

    Institute of Scientific and Technical Information of China (English)

    WANG Qingguo; QU Zhaoming; WANG Yilong


    To investigate the quantitative relationship between the electromagnetic-shielding property of composites and the distribution of inclusions,a scheme for predicting the shielding effectiveness of composites containing variously-distributed flaky inclusions is proposed.The scheme is based on equivalent parameters of homogeneous comparison materials and the plane-wave shielding theory.It leads to explicit formulas for the shielding effectiveness of multi-layered composites in terms of microstructural parameters that characterize the shape,distribution and orientation of the inclusions.For single layer composite that contains random and aligned flaky silver-coated carbonyl-iron particles with fractions of different volume,the predicted shielding effectiveness agrees well with the experimental data.As for composites containing aligned flaky particles,the shielding effectiveness obtained by the proposed scheme and experiment data is higher than that the random case,e.g.about 20 dB higher at 750 MHz.The proposed scheme is a straightforward method for optimizing future composite designs.

  19. Materials engineering data base (United States)


    The various types of materials related data that exist at the NASA Marshall Space Flight Center and compiled into databases which could be accessed by all the NASA centers and by other contractors, are presented.

  20. Shielding considerations for an operating room based intraoperative electron radiotherapy unit. (United States)

    Mills, M D; Almond, P R; Boyer, A L; Ochran, T G; Madigan, W; Rich, T A; Dally, E B


    The leakage radiation characteristics of a dedicated intraoperative radiotherapy linear accelerator have been measured on a machine designed to minimize the shielding required to allow it to be placed in an operating room suite. The scattering foil design was optimized to produce a flat beam for the field sizes employed while generating minimal bremsstrahlung contamination over the available energy range. More lead shielding was used in the treatment head than is used in conventional accelerators. A small amount of borated polyethylene shielding was also employed since neutron production was present at measurable levels. The room shielding installed in the operating room was demonstrated to be adequate to treat at least 20 patients each month to an average dose of 20 Gy. The worst case exposure was found to be 73% maximum permissible exposure. Administrative control was required for adjoining areas when calibrations and maintenance were performed.

  1. Tissue equivalent proportional counter microdosimetry measurements utililzed aboard aircraft and in accelerator based space radiation shielding studies (United States)

    Gersey, Brad; Wilkins, Richard

    The space radiation environment presents a potential hazard to the humans, electronics and materials that are exposed to it. Particle accelerator facilities such as the NASA Space Ra-diation Laboratory (NSRL) and Loma Linda University Medical Center (LLUMC) provide particle radiation of specie and energy within the range of that found in the space radiation environment. Experiments performed at these facilities determine various endpoints for bio-logical, electronic and materials exposures. A critical factor in the performance of rigorous scientific studies of this type is accurate dosimetric measurements of the exposures. A Tissue Equivalent Proportional Counter (TEPC) is a microdosimeter that may be used to measure absorbed dose, average quality factor (Q) and dose equivalent of the particle beam utilized in these experiments. In this work, results from a variety of space radiation shielding studies where a TEPC was used to perform dosimetry in the particle beam will be presented. These results compare the absorbed dose and dose equivalent measured downstream of equal density thicknesses of stan-dard and multifunctional shielding materials. The standard materials chosen for these shielding studies included High-Density Polyethylene (HDPE) and aluminum alloy, while the multifunc-tional materials included carbon composite infused with single walled carbon nanotubes. High energy particles including proton, silicon and iron nuclei were chosen as the incident radia-tion for these studies. Further, TEPC results from measurements taken during flights aboard ER-2 and KC-135 aircraft will also be discussed. Results from these flight studies include TEPC measurements for shielded and unshielded conditions as well as the effect of vibration and electromagnetic exposures on the TEPC operation. The data selected for presentation will highlight the utility of the TEPC in space radiation studies, and in shielding studies in particular. The lineal energy response function of the

  2. Development of a double plasma gun device for investigation of effects of vapor shielding on erosion of PFC materials under ELM-like pulsed plasma bombardment (United States)

    Sakuma, I.; Iwamoto, D.; Kitagawa, Y.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.


    It is considered that thermal transient events such as type I edge localized modes (ELMs) could limit the lifetime of plasma-facing components (PFCs) in ITER. We have investigated surface damage of tungsten (W) materials under transient heat and particle loads by using a magnetized coaxial plasma gun (MCPG) device at University of Hyogo. The capacitor bank energy for the plasma discharge is 144 kJ (2.88 mF, 10 kVmax). Surface melting of a W material was clearly observed at the energy density of ˜2 MJ/m2. It is known that surface melting and evaporation during a transient heat load could generate a vapor cloud layer in front of the target material [1]. Then, the subsequent erosion could be reduced by the vapor shielding effect. In this study, we introduce a new experiment using two MCPG devices (MCPG-1, 2) to understand vapor shielding effects of a W surface under ELM-like pulsed plasma bombardment. The capacitor bank energy of MCPG-2 is almost same as that of MCPG-1. The second plasmoid is applied with a variable delay time after the plasmoid produced by MCPG-1. Then, a vapor cloud layer could shield the second plasma load. To verify the vapor shielding effects, surface damage of a W material is investigated by changing the delay time. In the conference, the preliminary experimental results will be shown.[4pt] [1] A. Hassanein et al., J. Nucl. Mater. 390-391, pp. 777-780 (2009).

  3. A model-based approach of scatter dose contributions and efficiency of apron shielding for radiation protection in CT. (United States)

    Weber, N; Monnin, P; Elandoy, C; Ding, S


    Given the contribution of scattered radiations to patient dose in CT, apron shielding is often used for radiation protection. In this study the efficiency of apron was assessed with a model-based approach of the contributions of the four scatter sources in CT, i.e. external scattered radiations from the tube and table, internal scatter from the patient and backscatter from the shielding. For this purpose, CTDI phantoms filled with thermoluminescent dosimeters were scanned without apron, and then with an apron at 0, 2.5 and 5 cm from the primary field. Scatter from the tube was measured separately in air. The scatter contributions were separated and mathematically modelled. The protective efficiency of the apron was low, only 1.5% in scatter dose reduction on average. The apron at 0 cm from the beam lowered the dose by 7.5% at the phantom bottom but increased the dose by 2% at the top (backscatter) and did not affect the centre. When the apron was placed at 2.5 or 5 cm, the results were intermediate to the one obtained with the shielding at 0 cm and without shielding. The apron effectiveness is finally limited to the small fraction of external scattered radiation.

  4. Advanced Borobond™ Shields for Nuclear Materials Containment and Borobond™ Immobilization of Volatile Fission Products - Final CRADA Report

    Energy Technology Data Exchange (ETDEWEB)

    Wagh, Arun S. [Argonne National Lab. (ANL), Argonne, IL (United States)


    Borobond is a company-proprietary material developed by the CRADA partner in collaboration with Argonne, and is based on Argonne's Ceramicrete technology. It is being used by DOE for nuclear materials safe storage, and Boron Products, LLC is the manufacturer and supplier of Borobond.

  5. Preliminary Analysis of a Water Shield for a Surface Power Reactor (United States)

    Pearson, J. Boise


    A water based shielding system is being investigated for use on initial lunar surface power systems. The use of water may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. A simple 1-D thermal model indicates the necessity of natural convection to maintain acceptable temperatures and pressures in the water shield. CFD analysis is done to quantify the natural convection in the shield, and predicts sufficient natural convection to transfer heat through the shield with small temperature gradients. A test program will he designed to experimentally verify the thermal hydraulic performance of the shield, and to anchor the CFD models to experimental results.

  6. Design of ITER vacuum vessel in-wall shielding

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X., E-mail: [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Ioki, K. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Morimoto, M. [Mitsubishi Heavy Industries, 1-1, Wadasaki-cho 1-chome, Hyogo-ku, Kobe (Japan); Choi, C.H.; Utin, Y.; Sborchia, C. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); TaiLhardat, O. [Assystem EOS, ZAC SAINT MARTIN, 23 rue Benjamin Franklin, 84120 Pertuis (France); Mille, B.; Terasawa, A.; Gribov, Y.; Barabash, V.; Polunovskiy, E.; Dani, S. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Pathak, H.; Raval, J. [ITER-India, Institute for Plasma Research, Gandhinagar 382025 (India); Liu, S.; Lu, M.; Du, S. [Institute of Plasma Physics, China Academy of Sciences, Shushanhu Road 350, Hefei (China)


    The ITER vacuum vessel is a torus-shaped, double wall structure. The space between the double walls of the VV is filled with in-wall shielding (IWS) and cooling water. The main purpose of the in-wall shielding is to provide neutron shielding together with the blanket and VV shells and water during ITER plasma operation and to reduce the ripple of the Toroidal magnetic field. Based on ITER vacuum vessel structure and related requirements, in-wall shielding are designed as about 8900 individual blocks with different sizes and several different materials distributed over nine vessel sectors and nine field joints of vessel sectors. This paper presents the design of the IWS, considering loads, structural stresses and assembly method, and also shows neutron shielding effect and TF ripple reduced by the IWS.

  7. Comparison of some lead and non-lead based glass systems, standard shielding concretes and commercial window glasses in terms of shielding parameters in the energy region of 1 keV-100 GeV: A comparative study (United States)

    Kurudirek, Murat; Özdemir, Yüksel; Şimşek, Önder; Durak, Rıdvan


    The effective atomic numbers, Z eff of some glass systems with and without Pb have been calculated in the energy region of 1 keV-100 GeV including the K absorption edges of high Z elements present in the glass. Also, these glass systems have been compared with some standard shielding concretes and commercial window glasses in terms of mean free paths and total mass attenuation coefficients in the continuous energy range. Comparisons with experiments were also provided wherever possible for glasses. It has been observed that the glass systems without Pb have higher values of Z eff than that of Pb based glasses at some high energy regions even if they have lower mean atomic numbers than Pb based glasses. When compared with some standard shielding concretes and commercial window glasses, generally it has been shown that the given glass systems have superior properties than concretes and window glasses with respect to the radiation-shielding properties, thus confirming the availability of using these glasses as substitutes for some shielding concretes and commercial window glasses to improve radiation-shielding properties in the continuous energy region.

  8. Magnetic shielding for superconducting RF cavities (United States)

    Masuzawa, M.; Terashima, A.; Tsuchiya, K.; Ueki, R.


    Magnetic shielding is a key technology for superconducting radio frequency (RF) cavities. There are basically two approaches for shielding: (1) surround the cavity of interest with high permeability material and divert magnetic flux around it (passive shielding); and (2) create a magnetic field using coils that cancels the ambient magnetic field in the area of interest (active shielding). The choice of approach depends on the magnitude of the ambient magnetic field, residual magnetic field tolerance, shape of the magnetic shield, usage, cost, etc. However, passive shielding is more commonly used for superconducting RF cavities. The issue with passive shielding is that as the volume to be shielded increases, the size of the shielding material increases, thereby leading to cost increase. A recent trend is to place a magnetic shield in a cryogenic environment inside a cryostat, very close to the cavities, reducing the size and volume of the magnetic shield. In this case, the shielding effectiveness at cryogenic temperatures becomes important. We measured the permeabilities of various shielding materials at both room temperature and cryogenic temperature (4 K) and studied shielding degradation at that cryogenic temperature.

  9. Shielding in Mental Health Hospitals

    Directory of Open Access Journals (Sweden)

    Espen W. Haugom


    Full Text Available Shielding is defined as the confinement of patients to a single room or a separate unit/area inside the ward, accompanied by a member of staff. It is understood as both a treatment and a control. The purpose of this study is to examine how staff in psychiatric hospitals describe and assess shielding. This qualitative study uses a descriptive and exploratory design with an inductive approach. The material was acquired through the Acute Network (in Psychiatry nationwide shielding project. Data collection was carried out by the staff, who described the shielding procedure on a semi-structured form. The analysis was inspired by Graneheim and Lundman’s qualitative content analysis. Shielding has been described as an ambiguous practice, that is, shielding can be understood in several ways. There is a clear tension between shielding as a control and shielding as a treatment, with control being described as more important. The important therapeutic elements of shielding have also been mentioned, and shielding involves isolation to different degrees.

  10. Lignin-Based Thermoplastic Materials. (United States)

    Wang, Chao; Kelley, Stephen S; Venditti, Richard A


    Lignin-based thermoplastic materials have attracted increasing interest as sustainable, cost-effective, and biodegradable alternatives for petroleum-based thermoplastics. As an amorphous thermoplastic material, lignin has a relatively high glass-transition temperature and also undergoes radical-induced self-condensation at high temperatures, which limits its thermal processability. Additionally, lignin-based materials are usually brittle and exhibit poor mechanical properties. To improve the thermoplasticity and mechanical properties of technical lignin, polymers or plasticizers are usually integrated with lignin by blending or chemical modification. This Review attempts to cover the reported approaches towards the development of lignin-based thermoplastic materials on the basis of published information. Approaches reviewed include plasticization, blending with miscible polymers, and chemical modifications by esterification, etherification, polymer grafting, and copolymerization. Those lignin-based thermoplastic materials are expected to show applications as engineering plastics, polymeric foams, thermoplastic elastomers, and carbon-fiber precursors.

  11. Shielding property of different prosthetic materials to shield radiation of 125I seed%基托材料对125I粒子屏蔽效果的初步研究

    Institute of Scientific and Technical Information of China (English)

    白阳; 王燕一; 张蕾; 步荣发


    目的 探讨应用赝复体或修复体承载 125I粒子进行肿瘤治疗时,不同修复材料对 125I粒子辐射的屏蔽作用.方法 125I粒子为放射源,用热释光剂量元件进行测量,建立体外照射模型.载体选用纯钛板、钴铬合金板、聚甲基丙烯酸甲酯板,以铅板为对照,比较各种材料板的屏蔽效果.结果 在距离放射源10 mm处,经屏蔽后剂量分别为0.09 mm纯钛板2.805 mGy,0.48 mm钛板1.082 mGy,0.410、0.671 mm钴铬合金板为0.390、0.261 mGy,1.685 mm聚甲基丙烯酸甲酯板为2.885 mGy.结论 钴铬合金的屏蔽效果优于其他材料,聚甲基丙烯酸甲酯对 125I粒子具有一定屏蔽作用,与0.557 mm以上钛板共用可达到铅板防护效果.%Objective To investigation the shielding property to 125I of several different prosthetic materials used in clinical when prostheses are used as carriers of 125I seed in tumor treatment. Methods125I seeds were taken as the radiation sources to establish a model in vitro and the radiation doses were measured by thermoluminescent dosemeters(TLD). The shielding property of titanium plate, cochrome plate, and poly methyl methacrylate(PMMA) plate were detected, calculated and compared with that of plumbum plate in the control group. Results The radiation doses of the radiation source at 10 mm distance through the following materials were measured, and the results are 2.805 mGy (0.09 mm thick titanium plate), 1.082 mGy (0.48 thick titanium plate),0.390 mGy (0.41 mm thick cochrome plate), and 0.261 mGy (0.67 mm′s cochrome plate), and 2.885 mGy (1.685 mm thick PMMA plate). ConclusionsThe shield property of cochrome is optimal. The poly methyl methacrylate behaves to some extend as a shield to the 125I seed which can shield the radiation as the effects of plumbum when adopted together with the 0.557 mm′s(or more)titanium plate.

  12. SU-C-BRB-02: Symmetric and Asymmetric MLC Based Lung Shielding and Dose Optimization During Translating Bed TBI

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, S; Kakakhel, MB [Pakistan Institute of Engineering & Applied Sciences (PIEAS), Islamabad (Pakistan); Ahmed, SBS; Hussain, A [Aga Khan University Hospital (AKUH), Karachi (Pakistan)


    Purpose: The primary aim was to introduce a dose optimization method for translating bed total body irradiation technique that ensures lung shielding dynamically. Symmetric and asymmetric dynamic MLC apertures were employed for this purpose. Methods: The MLC aperture sizes were defined based on the radiological depth values along the divergent ray lines passing through the individual CT slices. Based on these RD values, asymmetrically shaped MLC apertures were defined every 9 mm of the phantom in superior-inferior direction. Individual MLC files were created with MATLAB™ and were imported into Eclipse™ treatment planning system for dose calculations. Lungs can be shielded to an optimum level by reducing the MLC aperture width over the lungs. The process was repeated with symmetrically shaped apertures. Results: Dose-volume histogram (DVH) analysis shows that the asymmetric MLC based technique provides better dose coverage to the body and optimum shielding of the lungs compared to symmetrically shaped beam apertures. Midline dose homogeneity is within ±3% with asymmetric MLC apertures whereas it remains within ±4.5% with symmetric ones (except head region where it drops down to −7%). The substantial over and under dosage of ±5% at tissue interfaces has been reduced to ±2% with asymmetric MLC technique. Lungs dose can be reduced to any desired limit. In this experiment lungs dose was reduced to 80% of the prescribed dose, as was desired. Conclusion: The novel asymmetric MLC based technique assures optimum shielding of OARs (e.g. lungs) and better 3-D dose homogeneity and body-dose coverage in comparison with the symmetric MLC aperture optimization. The authors acknowledge the financial and infrastructural support provided by Pakistan Institute of Engineering & Applied Sciences (PIEAS), Islamabad and Aga Khan University Hospital (AKUH), Karachi during the course of this research project. Authors have no conflict of interest with any national / international

  13. Benchmark studies of the effectiveness of structural and internal materials as radiation shielding for the international space station (United States)

    Miller, J.; Zeitlin, C.; Cucinotta, F. A.; Heilbronn, L.; Stephens, D.; Wilson, J. W.


    Accelerator-based measurements and model calculations have been used to study the heavy-ion radiation transport properties of materials in use on the International Space Station (ISS). Samples of the ISS aluminum outer hull were augmented with various configurations of internal wall material and polyethylene. The materials were bombarded with high-energy iron ions characteristic of a significant part of the galactic cosmic-ray (GCR) heavy-ion spectrum. Transmitted primary ions and charged fragments produced in nuclear collisions in the materials were measured near the beam axis, and a model was used to extrapolate from the data to lower beam energies and to a lighter ion. For the materials and ions studied, at incident particle energies from 1037 MeV/nucleon down to at least 600 MeV/nucleon, nuclear fragmentation reduces the average dose and dose equivalent per incident ion. At energies below 400 MeV/nucleon, the calculation predicts that as material is added, increased ionization energy loss produces increases in some dosimetric quantities. These limited results suggest that the addition of modest amounts of polyethylene or similar material to the interior of the ISS will reduce the dose to ISS crews from space radiation; however, the radiation transport properties of ISS materials should be evaluated with a realistic space radiation field. Copyright 2003 by Radiation Research Society.

  14. Noise Modeling From Conductive Shields Using Kirchhoff Equations. (United States)

    Sandin, Henrik J; Volegov, Petr L; Espy, Michelle A; Matlashov, Andrei N; Savukov, Igor M; Schultz, Larry J


    Progress in the development of high-sensitivity magnetic-field measurements has stimulated interest in understanding the magnetic noise of conductive materials, especially of magnetic shields based on high-permeability materials and/or high-conductivity materials. For example, SQUIDs and atomic magnetometers have been used in many experiments with mu-metal shields, and additionally SQUID systems frequently have radio frequency shielding based on thin conductive materials. Typical existing approaches to modeling noise only work with simple shield and sensor geometries while common experimental setups today consist of multiple sensor systems with complex shield geometries. With complex sensor arrays used in, for example, MEG and Ultra Low Field MRI studies, knowledge of the noise correlation between sensors is as important as knowledge of the noise itself. This is crucial for incorporating efficient noise cancelation schemes for the system. We developed an approach that allows us to calculate the Johnson noise for arbitrary shaped shields and multiple sensor systems. The approach is efficient enough to be able to run on a single PC system and return results on a minute scale. With a multiple sensor system our approach calculates not only the noise for each sensor but also the noise correlation matrix between sensors. Here we will show how the algorithm can be implemented.

  15. Study on Electromagnetic Shielding and Absorptive Materials Used for Landmine Shell%地雷壳体电磁屏蔽吸收材料应用研究

    Institute of Scientific and Technical Information of China (English)

    罗先南; 方向; 高振儒; 刘君; 方鲲


    采用不锈钢纤维( SSF)填充丙烯腈-丁二烯-苯乙烯塑料制备导电工程塑料,并测试材料的物理和电磁屏蔽吸收性能.结果表明,SSF质量分数为15%时,能较好地兼顾材料的物理性能与加工难度,且在强电磁源主要频段有20 dB以上的屏蔽效能.低频磁场屏蔽效能测试结果表明,材料对低频磁场影响甚微,不影响地雷磁引信正常工作.该材料有助于提高磁引信地雷在高功率电磁环境下的生存能力.%A new kinds of conductive engineering material was prepared, by using stainless steel fibers ( SSF ) to fill acrylonitrile-butadiene-styrenecopolymer, and physical properties and electromagnetic shielding and absorptive capabilities of the new materials were tested. The results showed that when the mass fraction of SSF was 15%, the new material was better balanced between the physical properties and the difficulty of processing. The electromagnetic shielding effect was more than 20 dB in main frequency band of high power microwave sources. The test of shielding effect in low frequency magnetic field showed that the new material had few influence on low frequency magnetic field and magnetic fuze of landmine could normally work. The new material could promote the viability of landmine with magnetic fuze in high power electromagnetic environment.

  16. BMFO-PVDF electrospun fiber based tunable metamaterial structures for electromagnetic interference shielding in microwave frequency region (United States)

    Revathi, Venkatachalam; Dinesh Kumar, Sakthivel; Subramanian, Venkatachalam; Chellamuthu, Muthamizhchelvan


    Metamaterial structures are artificial structures that are useful in controlling the flow of electromagnetic radiation. In this paper, composite fibers of sub-micron thickness of barium substituted magnesium ferrite (Ba0.2Mg0.8Fe2O4) - polyvinylidene fluoride obtained by electrospinning is used as a substrate to design electromagnetic interference shielding structures. While electrospinning improves the ferroelectric properties of the polyvinylidene fluoride, the presence of barium magnesium ferrite modifies the magnetic property of the composite fiber. The dielectric and magnetic properties at microwave frequency measured using microwave cavity perturbation technique are used to design the reflection as well as absorption based tunable metamaterial structures for electromagnetic interference shielding in microwave frequency region. For one of the structures, the simulation indicates that single negative metamaterial structure becomes a double negative metamaterial under the external magnetic field.

  17. Determination and Fabrication of New Shield Super Alloys Materials for Nuclear Reactor Safety by Experiments and Cern-Fluka Monte Carlo Simulation Code, Geant4 and WinXCom (United States)

    Aygun, Bünyamin; Korkut, Turgay; Karabulut, Abdulhalik


    Despite the possibility of depletion of fossil fuels increasing energy needs the use of radiation tends to increase. Recently the security-focused debate about planned nuclear power plants still continues. The objective of this thesis is to prevent the radiation spread from nuclear reactors into the environment. In order to do this, we produced higher performanced of new shielding materials which are high radiation holders in reactors operation. Some additives used in new shielding materials; some of iron (Fe), rhenium (Re), nickel (Ni), chromium (Cr), boron (B), copper (Cu), tungsten (W), tantalum (Ta), boron carbide (B4C). The results of this experiments indicated that these materials are good shields against gamma and neutrons. The powder metallurgy technique was used to produce new shielding materials. CERN - FLUKA Geant4 Monte Carlo simulation code and WinXCom were used for determination of the percentages of high temperature resistant and high-level fast neutron and gamma shielding materials participated components. Super alloys was produced and then the experimental fast neutron dose equivalent measurements and gamma radiation absorpsion of the new shielding materials were carried out. The produced products to be used safely reactors not only in nuclear medicine, in the treatment room, for the storage of nuclear waste, nuclear research laboratories, against cosmic radiation in space vehicles and has the qualities.

  18. Model-based acoustic substitution source methods for assessing shielding measures applied to trains

    NARCIS (Netherlands)

    Geerlings, A.C.; Thompson, D.J.; Verheij, J.W.


    A promising means of reducing the rolling noise from trains is local shielding in the form of vehicle-mounted shrouds combined with low trackside barriers. This is much less visually intrusive than classic lineside noise barriers. Various experimental methods have been proposed that allow the perfor

  19. Polyphosphazine-based polymer materials (United States)

    Fox, Robert V.; Avci, Recep; Groenewold, Gary S.


    Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

  20. Application of Particle Swarm Optimization Algorithm in Design of Multilayered Planar Shielding Body

    Institute of Scientific and Technical Information of China (English)

    FUJiwei; HOUChaozhen; DOULihua


    Based on the basic electromagnetic wave propagation theory in this article, the Particle swarm optimization algorithm (PSO) is used in the design of the multilayered composite materials and the thickness of shielding body by the existent multilayered planar composite elec-tromagnetic shielding materials model, the different shielding materials of each layer can be designed under some kinds of circumstances: the prespecified Shielding effectiveness (SE), different incident angle and the prespecified band of frequencies. Finally the algorithm is simulated. At the same time the similar procedure can be implemented by Genetic algorithm (GA). The results acquired by particle swarm optimization algorithm are compared with there sults acquired by the genetic algorithm. The results indicate that: the particle swarm optimization algorithm is much better than the genetic algorithm not only in convergence speed but also in simplicity. So a more effective method (Particle Swarm Optimization algorithm) is offered for the design of the multilayered composite shielding materials.

  1. Bias reduction for Satellite Based Precipitation Estimates using statistical transformations in Guiana Shield (United States)

    Ringard, Justine; Becker, Melanie; Seyler, Frederique; Linguet, Laurent


    Currently satellite-based precipitation estimates exhibit considerable biases, and there have been many efforts to reduce these biases by merging surface gauge measurements with satellite-based estimates. In Guiana Shield all products exhibited better performances during the dry season (August- December). All products greatly overestimate very low intensities (50 mm). Moreover the responses of each product are different according to hydro climatic regimes. The aim of this study is to correct spatially the bias of precipitation, and compare various correction methods to define the best methods depending on the rainfall characteristic correcting (intensity, frequency). Four satellites products are used: Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) research product (3B42V7) and real time product (3B42RT), the Precipitation Estimation from Remotely-Sensed Information using Artificial Neural Network (PERSIANN) and the NOAA Climate Prediction Center (CPC) Morphing technique (CMORPH), for six hydro climatic regimes between 2001 and 2012. Several statistical transformations are used to correct the bias. Statistical transformations attempt to find a function h that maps a simulated variable Ps such that its new distribution equals the distribution of the observed variable Po. The first is the use of a distribution derived transformations which is a mixture of the Bernoulli and the Gamma distribution, where the Bernoulli distribution is used to model the probability of precipitation occurrence and the Gamma distribution used to model precipitation intensities. The second a quantile-quantile relation using parametric transformation, and the last one is a common approach using the empirical CDF of observed and modelled values instead of assuming parametric distributions. For each correction 30% of both, simulated and observed data sets, are used to calibrate and the other part used to validate. The validation are test with statistical

  2. Preliminary Thermal Design of Cryogenic Radiation Shielding (United States)

    Li, Xiaoyi; Mustafi, Shuvo; Boutte, Alvin


    Cryogenic Hydrogen Radiation Shielding (CHRS) is the most mass efficient material radiation shielding strategy for human spaceflight beyond low Earth orbit (LEO). Future human space flight, mission beyond LEO could exceed one year in duration. Previous radiation studies showed that in order to protect the astronauts from space radiation with an annual allowable radiation dose less than 500 mSv, 140 kgm2 of polyethylene is necessary. For a typical crew module that is 4 meter in diameter and 8 meter in length. The mass of polyethylene radiation shielding required would be more than 17,500 kg. The same radiation study found that the required hydrogen shielding for the same allowable radiation dose is 40 kgm2, and the mass of hydrogen required would be 5, 000 kg. Cryogenic hydrogen has higher densities and can be stored in relatively small containment vessels. However, the CHRS system needs a sophisticated thermal system which prevents the cryogenic hydrogen from evaporating during the mission. This study designed a cryogenic thermal system that protects the CHRS from hydrogen evaporation for one to up to three year mission. The design also includes a ground based cooling system that can subcool and freeze liquid hydrogen. The final results show that the CHRS with its required thermal protection system is nearly half of the mass of polyethylene radiation shielding.

  3. Explicit formulation of the J2-integral in anisotropic materials and its application in microcrack shielding problems

    Institute of Scientific and Technical Information of China (English)

    陈宜亨; 马浩


    The explicit formulation of the J2-integral in anisotropic bodies and its application in microcrack shielding problems are discussed. With analytical treatments and numerical examinations, it is proved that there is a redistribution law for the remote J-integral in a discrete model of microcrack shielding problems, i.e. the projected conservation law of the Jk-vector. In this law, the J2-integral which was disregarded by Herrmann (1981) is proved to be of the same significance as the J1-integral. It is also concluded that the two energy dissipative processes due to the mi crocrack damage, i. e. the reduction in the effective moduli and the release of residual stresses, can be described by using the dissipation of the remote J-integral spreading across the microcrack damage zone.

  4. Measurements of neutron effective doses and attenuation lengths for shielding materials at the heavy-ion medical accelerator in Chiba. (United States)

    Kumamoto, Yoshikazu; Noda, Yutaka; Sato, Yukio; Kanai, Tatsuaki; Murakami, Takeshi


    The effective doses and attenuation lengths for concrete and iron were measured for the design of heavy ion facilities. Neutrons were produced through the reaction of copper, carbon, and lead bombarded by carbon ions at 230 and 400 MeV.A, neon ions at 400 and 600 MeV.A, and silicon ions at 600 and 800 MeV.A. The detectors used were a Linus and a Andersson-Braun-type rem counter and a detector based on the activation of a plastic scintillator. Representative effective dose rates (in units of 10(-8) microSv h(-1) pps(-1) at 1 m from the incident target surface, where pps means particles per second) and the attenuation lengths (in units of m) were 9.4 x 10(4), 0.46 for carbon ions at 230 MeV.A; 8.9 x 10(5), 0.48 for carbon ions at 400 MeV.A; 9.3 x 10(5), 0.48 for neon ions at 400 MeV.A; 3.8 x 10(6), 0.50 for neon ions at 600 MeV.A; 3.9 x 10(6), 0.50 for silicon ions at 600 MeV.A; and 1.1 x 10(7), 0.51 for silicon ions at 800 MeV.A. The attenuation provided by an iron plate approximately 20 cm thick (nearly equal to the attenuation length) corresponded to that of a 50-cm block of concrete in the present energy range. Miscellaneous results, such as the angular distributions of the neutron effective dose, narrow beam attenuation experiments, decay of gamma-ray doses after the bombardment of targets, doses around an irradiation room, order effects in the multi-layer (concrete and iron) shielding, the doses from different targets, the doses measured with a scintillator activation detector, the gamma-ray doses out of walls and the ratio of the response between the Andersson-Braun-type and the Linus rem counters are also reported.

  5. Study on borate glass system containing with Bi 2O 3 and BaO for gamma-rays shielding materials: Comparison with PbO (United States)

    Kaewkhao, J.; Pokaipisit, A.; Limsuwan, P.


    In this work, the mass attenuation coefficients and shielding parameters of borate glass matrices containing with Bi 2O 3 and BaO have been investigated at 662 keV, and compare with PbO in same glass structure. The theoretical values were calculated by WinXCom software and compare with experiential data. The results found that the mass attenuation coefficients were increased with increasing of Bi 2O 3, BaO and PbO concentration, due to increase photoelectric absorption of all glass samples. However, Compton scattering gives dominant contribution to the total mass attenuation coefficients for studied glass samples. Moreover the half value layers (HVL) of glass samples were also better than ordinary concretes and commercial window glass. These results reflecting that the Bi-based glass can use replace Pb in radiation shielding glass. In the case of Ba, may be can use at appropriate energy such as X-rays or lower.

  6. Radiation Shielding Optimization on Mars (United States)

    Slaba, Tony C.; Mertens, Chris J.; Blattnig, Steve R.


    Future space missions to Mars will require radiation shielding to be optimized for deep space transit and an extended stay on the surface. In deep space, increased shielding levels and material optimization will reduce the exposure from most solar particle events (SPE) but are less effective at shielding against galactic cosmic rays (GCR). On the surface, the shielding provided by the Martian atmosphere greatly reduces the exposure from most SPE, and long-term GCR exposure is a primary concern. Previous work has shown that in deep space, additional shielding of common materials such as aluminum or polyethylene does not significantly reduce the GCR exposure. In this work, it is shown that on the Martian surface, almost any amount of aluminum shielding increases exposure levels for humans. The increased exposure levels are attributed to neutron production in the shield and Martian regolith as well as the electromagnetic cascade induced in the Martian atmosphere. This result is significant for optimization of vehicle and shield designs intended for the surface of Mars.

  7. 硫酸渣辐射屏蔽材料制备与效果评价%Preparation and Effect Assessment of Gamma Ray Shielding Materials Containing Pyrite Cinder

    Institute of Scientific and Technical Information of China (English)

    王烨; 张晓文; 王续琨; 钟永明; 吕俊文; 彭莹; 李密


    采用直接掺杂法分别制备了硫酸渣—混凝土、硫酸渣—粉煤灰—混凝土和铅—混凝土屏蔽材料,用NaI( TI)探测器、多道脉冲幅度分析仪和WINXCOM软件分析它们对γ射线的辐射防护能力。结果表明:硫酸渣制备的屏蔽材料辐射防护性能优于已有的石灰岩制备的屏蔽材料和FPPB屏蔽材料,可用作射线屏蔽材料,并有望实现固体废弃物的合理利用。%Pyrite cinder-concrete,pyrite cinder-fly ash-concrete and lead-concrete shielding materials have been prepared by means of direct doping. NaI ( TI) detectors,multi-channel pulse amplitude analyzer and WinXCOM software were used to test and analyze their radia-tion shielding property. The results show that the radiation shielding property of shielding material containing pyrite cinder is better than the existing shielding materials prepared from limestone and FPPB. Consequently,it can be used effectively as shielding materials against gamma radiation,and is expected to achieve the goal of rational utilization of solid waste.

  8. Beta radiation shielding with lead and plastic: effect on bremsstrahlung radiation when switching the shielding order. (United States)

    Van Pelt, Wesley R; Drzyzga, Michael


    Lead and plastic are commonly used to shield beta radiation. Radiation protection literature is ubiquitous in advising the placement of plastic first to absorb all the beta particles before any lead shielding is used. This advice is based on the well established theory that radiative losses (bremsstrahlung production) are more prevalent in higher atomic number (Z) materials than in low Z materials. Using 32P beta radiation, we measured bremsstrahlung photons transmitted through lead and plastic (Lucite) shielding in different test configurations to determine the relative efficacy of lead alone, plastic alone, and the positional order of lead and plastic. With the source (32P) and detector held at a constant separation distance, we inserted lead and/or plastic absorbers and measured the reduction in bremsstrahlung radiation level measured by the detector. With these test conditions, analysis of measured bremsstrahlung radiation in various thicknesses and configurations of lead and plastic shielding shows the following: placing plastic first vs. lead first reduces the transmitted radiation level only marginally (10% to 40%); 2 mm of additional lead is sufficient to correct the "mistake" of placing the lead first; and for equal thicknesses or weights of lead and plastic, lead is a more efficient radiation shield than plastic.

  9. SHIELD 1.0: development of a shielding calculator program in diagnostic radiology; SHIELD 1.0: desenvolvimento de um programa de calculo de blindagem em radiodiagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Romulo R.; Real, Jessica V.; Luz, Renata M. da [Hospital Sao Lucas (PUCRS), Porto Alegre, RS (Brazil); Friedrich, Barbara Q.; Silva, Ana Maria Marques da, E-mail: [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)


    In shielding calculation of radiological facilities, several parameters are required, such as occupancy, use factor, number of patients, source-barrier distance, area type (controlled and uncontrolled), radiation (primary or secondary) and material used in the barrier. The shielding design optimization requires a review of several options about the physical facility design and, mainly, the achievement of the best cost-benefit relationship for the shielding material. To facilitate the development of this kind of design, a program to calculate the shielding in diagnostic radiology was implemented, based on data and limits established by National Council on Radiation Protection and Measurements (NCRP) 147 and SVS-MS 453/98. The program was developed in C⌗ language, and presents a graphical interface for user data input and reporting capabilities. The module initially implemented, called SHIELD 1.0, refers to calculating barriers for conventional X-ray rooms. The program validation was performed by the comparison with the results of examples of shielding calculations presented in NCRP 147.

  10. Knitted radar absorbing materials (RAM) based on nickel-cobalt magnetic materials (United States)

    Teber, Ahmet; Unver, Ibrahim; Kavas, Huseyin; Aktas, Bekir; Bansal, Rajeev


    There has been a long-standing interest in the development of flexible, lightweight, thin, and reconfigurable radar absorbing materials (RAM) for military applications such as camouflaging ground-based hardware against airborne radar observation. The use of polymeric Polyacrylonitrile (PAN) fabrics as a host matrix for magnetic metal nano-particles (either at the yarn-stage or after weaving the fabric) for shielding and absorbing applications has been described in the literature. In our experimental investigation, the relative concentrations of Nickel and Cobalt as well as the coating time are varied with a view to optimizing the microwave absorption characteristics of the resulting PAN-based composite material in the radar-frequency bands (X, Ku, and K). It is found that the PAN samples with the shortest coating time have the best return losses (under -20 dB return loss over a moderate bandwidth).

  11. Comparative study of lead borate and bismuth lead borate glass systems as gamma-radiation shielding materials (United States)

    Singh, Narveer; Singh, Kanwar Jit; Singh, Kulwant; Singh, Harvinder


    Gamma-ray mass attenuation coefficients have been measured experimentally and calculated theoretically for PbO-B 2O 3 and Bi 2O 3-PbO-B 2O 3 glass systems using narrow beam transmission method. These values have been used to calculate half value layer (HVL) parameter. These parameters have also been calculated theoretically for some standard radiation shielding concretes at same energies. Effect of replacing lead by bismuth has been analyzed in terms of density, molar volume and mass attenuation coefficient.

  12. X 射线屏蔽材料设计与制备的研究进展%Research progress of design and production of X-ray shielding materials

    Institute of Scientific and Technical Information of China (English)

    薛雯; 王富军; 王璐


    The characteristics and shielding mechanism of X-ray were introduced.The state-of-the-art of X-ray shielding materials was also reviewed in detail.Composite technology, gradient method and optimal design were put forward to fabricate lightweight and efficient radiation shielding materials.It was also pointed out that rare earth elements and nano-materials, as novel radiation shielding materials, should be used to enhance the overall performance of shielding material.%介绍X射线的特点及其屏蔽机制,详述X射线屏蔽材料的研究进展,提出材料的复合制备技术、梯度化设计以及遗传算法优化设计以制备轻质、高效、耐久的新型屏蔽材料,同时应发挥稀土元素和纳米材料的优势来增强屏蔽材料的综合性能。

  13. Secondary particle simulation analysis of high-energy56Fe ion inject various shielding material%高能56Fe离子入射屏蔽材料的次级粒子模拟分析

    Institute of Scientific and Technical Information of China (English)

    荀明珠; 何承发; 陆妩; 郭旗; 孙静; 刘默寒; 曾骏哲; 王信


    Background: The heavy ion in the galaxy cosmos rays with extremely high energy can be fatal to the astronaut and electronic device in the spacecraft. Purpose:This study aims to analyze the secondary particles produced by high energy heavy ion inject shielding materials of spacecraft.Methods:Based on the Monte-Carlo method simulation software Geant4, 1-GeV·u−156Fe ion incident four kinds of shielding material aluminum, aluminum carbon, polyethylene and water with 1.35-g·cm−2 mass thickness have been studied. The energy deposition in the absorber and deep-dose distribution produced by the transmitted primary particles and secondary electrons, secondary neutrons, secondary protons and secondary gamma have been analyzed. All produced secondary heavy particles and energies from four kinds of shielding materials after injected high-energy 1-GeV·u−156Fe ion have been investigated, and the shielding performance was analyzed and compared.Results:Polyethylene material absorbs the most energy, thus preserve best shielding performance whilst majority of secondary particles and energies are produced. The energy of secondary heavy ion is quadruple of that produced by aluminum material.Conclusion: Among all the secondary particles, secondary protons and secondary heavy ions with atom number between 22 and 26 make the maximal contributions.%空间辐射环境下的高能重离子入射屏蔽材料会产生大量次级粒子,为研究屏蔽材料产生的次级粒子对太空舱内辐射环境的影响,本文使用基于蒙特卡罗方法的Geant4软件模拟空间高能56Fe离子入射铝、碳、聚乙烯、水4种屏蔽材料,分析透射屏蔽体的初级粒子及由屏蔽材料产生的次级电子、次级中子、次级质子和次级γ的能谱以及水吸收体中的能量沉积和深度剂量分布。分析产生的次级重粒子类型和能量,比较4种屏蔽材料对高能Fe离子的屏蔽性能。结果表明,聚乙烯材料对高能重离子的

  14. Numerical analysis of Hall effect on the performance of magnetohydrodynamic heat shield system based on nonequilibrium Hall parameter model (United States)

    Li, Kai; Liu, Jun; Liu, Weiqiang


    Magnetohydrodynamic (MHD) heat shield system, a novel thermal protection technique in the hypersonic field, has been paid much attention in recent years. In the real flight condition, not only the Lorentz force but also the Hall electric field is induced by the interaction between ionized air post shock and magnetic field. In order to analyze the action mechanisms of the Hall effect, numerical methods of coupling thermochemical nonequilibrium flow field with externally applied magnetic field as well as the induced electric field are constructed and validated. Based on the nonequilibrium model of Hall parameter, numerical simulations of the MHD heat shield system is conducted under two different magnetic induction strengths (B0=0.2 T, 0.5 T) on a reentry capsule forebody. Results show that, the Hall effect is the same under the two magnetic induction strengths when the wall is assumed to be conductive. For this case, with the Hall effect taken into account, the Lorentz force counter stream diminishes a lot and the circumferential component dominates, resulting that the heat flux and shock-off distance approach the case without MHD control. However, for the insulating wall, the Hall effect acts in different ways under these two magnetic induction strengths. For this case, with the Hall effect taken into account, the performance of MHD heat shield system approaches the case neglecting the Hall effect when B0 equals 0.2 T. Such performance becomes worse when B0 equals 0.5 T and the aerothermal environment on the capsule shoulder is even worse than the case without MHD control.

  15. Protein-based composite materials

    Directory of Open Access Journals (Sweden)

    Xiao Hu


    Full Text Available Protein-based composite biomaterials have been actively pursued as they can encompass a range of physical properties to accommodate a broader spectrum of functional requirements, such as elasticity to support diverse tissues. By optimizing molecular interfaces between structural proteins, useful composite materials can be fabricated as films, gels, particles, and fibers, as well as for electrical and optical devices. Such systems provide analogies to more traditional synthetic polymers yet with expanded utility due to the material's tunability, mechanical properties, degradability, biocompatibility, and functionalization, such as for drug delivery, biosensors, and tissue regeneration.

  16. Adding effects of Ni and Mn on electromagnetic interference (EMI) shield of Sn-based architectural materials%镍和锰的添加对建筑材料Sn基纳米薄膜电磁屏蔽性能的影响

    Institute of Scientific and Technical Information of China (English)



    世界卫生组织已证明电磁波对公众健康会带来危害。然而,最近的相关建材与电磁波联系的研究主要集中在电磁产品上。生态环境更强调新产品的开发和无害环境。这些研究没有涉及健康保健、生活材料方面,尤其是那些大块高透明材料。因此,尝试向Sn基粉末中添加Ni和Mg而使材料具有电磁屏蔽性能。因其低费用的优势,建材使用此类三元系材料,即Sn−Al−Ni(SAN),Sn−Al−Mn(SAM)。研究了采用表面包覆方法时,粉末尺寸、Ni与Mn的比例、烟囱效应、孔隙度和厚度对材料屏蔽性能的影响机制。%It has been proved by the World Health Organization (WHO) that electromagnetic waves would bring threats to public health in the tourism environment. However, most of the recent research about the relationship between building materials and electromagnetic waves was mainly focused on the electromagnetic products. It has also been claimed that the related research can rarely been found. Generally, ecotourism more tends to emphasize on a development of a new product and uni-environment study. However, these studies did not concern much on the application for conformity of healthcare−living materials, particularly to those block high-transparency materials. Hence, this research approaches to conform the application of architectural technique for producing tin-based powder with the add-on of Ni and Mg, in order to discuss the fully anti-electromagnetic wave property of healthcare material. With a low-cost advantage, the application field of architecture defines the ternary powder system, namely Sn−Al−Ni (SAN) and Sn−Al−Mn (SAM). Additionally, the surface coating method can be implemented to review the influence of particle size, content ratio of Ni and Mn, stack effect, porosity and thickness to electromagnetic interference (EMI) mechanism.

  17. Conductive polymer-based material (United States)

    McDonald, William F.; Koren, Amy B.; Dourado, Sunil K.; Dulebohn, Joel I.; Hanchar, Robert J.


    Disclosed are polymer-based coatings and materials comprising (i) a polymeric composition including a polymer having side chains along a backbone forming the polymer, at least two of the side chains being substituted with a heteroatom selected from oxygen, nitrogen, sulfur, and phosphorus and combinations thereof; and (ii) a plurality of metal species distributed within the polymer. At least a portion of the heteroatoms may form part of a chelation complex with some or all of the metal species. In many embodiments, the metal species are present in a sufficient concentration to provide a conductive material, e.g., as a conductive coating on a substrate. The conductive materials may be useful as the thin film conducting or semi-conducting layers in organic electronic devices such as organic electroluminescent devices and organic thin film transistors.

  18. Electromagnetic shielding of thermal protection system for hypersonic vehicles (United States)

    Albano, M.; Micheli, D.; Gradoni, G.; Morles, R. B.; Marchetti, M.; Moglie, F.; Mariani Primiani, V.


    The numerical simulation and the measurement of electromagnetic shielding at microwave frequencies of thermal protection system for hypersonic vehicles is presented using nested reverberation chamber. An example of a possible thermal protection system for a re-entry vehicle is presented. This system based on carbon material is electromagnetically characterized. The characterization takes into account not only the materials but also the final assembly configuration of the thermal protection system. The frequency range is 2-8 GHz. The results of measurements and simulations show that the microwave shielding effectiveness of carbon materials is above 60 dB for a single tile and that the tile inter-distance is able to downgrade the shielding effectiveness on the average to about 40 dB.

  19. Optimal design of structural parameters for shield cutterhead based on fuzzy mathematics and multi-objective genetic algorithm

    Institute of Scientific and Technical Information of China (English)

    夏毅敏; 唐露; 暨智勇; 程永亮; 卞章括


    In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters for shield cutterhead is formulated, based on the complex engineering technical requirements. In the model, as the objective function of the model is a composite function of the strength and stiffness, the response surface method is applied to formulate the approximate function of objective function in order to reduce the solution scale of optimal problem. A multi-objective genetic algorithm is used to solve the cutterhead structure design problem and the change rule of the stress−strain with various structural parameters as well as their optimal values were researched under specific geological conditions. The results show that compared with original cutterhead structure scheme, the obtained optimal scheme of the cutterhead structure can greatly improve the strength and stiffness of the cutterhead, which can be seen from the reduction of its maximum equivalent stress by 21.2%, that of its maximum deformation by 0.75%, and that of its mass by 1.04%.

  20. Shielding design of a treatment room for an accelerator-based epithermal neutron irradiation facility for BNCT. (United States)

    Evans, J F; Blue, T E


    Protecting the facility personnel and the general public from radiation exposure is a primary safety concern of an accelerator-based epithermal neutron irradiation facility. This work makes an attempt at answering the questions "How much?" and "What kind?" of shielding will meet the occupational limits of such a facility. Shielding effectiveness is compared for ordinary and barytes concretes in combination with and without borated polyethylene. A calculational model was developed of a treatment room , patient "scatterer," and the epithermal neutron beam. The Monte Carlo code, MCNP, was used to compute the total effective dose equivalent rates at specific points of interest outside of the treatment room. A conservative occupational effective dose rate limit of 0.01 mSv h-1 was the guideline for this study. Conservative Monte Carlo calculations show that constructing the treatment room walls with 1.5 m of ordinary concrete, 1.2 m of barytes concrete, 1.0 m of ordinary concrete preceded by 10 cm of 5% boron-polyethylene, or 0.8 m of barytes concrete preceded by 10 cm of 5% boron-polyethylene will adequately protect facility personnel.

  1. Ground based materials science experiments (United States)

    Meyer, M. B.; Johnston, J. C.; Glasgow, T. K.


    The facilities at the Microgravity Materials Science Laboratory (MMSL) at the Lewis Research Center, created to offer immediate and low-cost access to ground-based testing facilities for industrial, academic, and government researchers, are described. The equipment in the MMSL falls into three categories: (1) devices which emulate some aspect of low gravitational forces, (2) specialized capabilities for 1-g development and refinement of microgravity experiments, and (3) functional duplicates of flight hardware. Equipment diagrams are included.

  2. Advanced Multifunctional MMOD Shield: Radiation Shielding Assessment (United States)

    Rojdev, Kristina; Christiansen, Eric


    Deep space missions must contend with a harsh radiation environment Impacts to crew and electronics. Need to invest in multifunctionality for spacecraft optimization. MMOD shield. Goals: Increase radiation mitigation potential. Retain overall MMOD shielding performance.


    Energy Technology Data Exchange (ETDEWEB)

    REID, ROBERT S. [Los Alamos National Laboratory; PEARSON, J. BOSIE [Los Alamos National Laboratory; STEWART, ERIC T. [Los Alamos National Laboratory


    Water based reactor shielding is being investigated for use on initial lunar surface power systems. A water shield may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. Natural convection in a 100 kWt lunar surface reactor shield design is evaluated with 2 kW power input to the water in the Water Shield Testbed (WST) at the NASA Marshall Space Flight Center. The experimental data from the WST is used to validate a CFD model. Performance of the water shield on the lunar surface is then predicted with a CFD model anchored to test data. The experiment had a maximum water temperature of 75 C. The CFD model with 1/6-g predicts a maximum water temperature of 88 C with the same heat load and external boundary conditions. This difference in maximum temperature does not greatly affect the structural design of the shield, and demonstrates that it may be possible to use water for a lunar reactor shield.

  4. Conduction mechanism in Polyaniline-flyash composite material for shielding against electromagnetic radiation in X-band & Ku band (United States)

    Singh, Avanish Pratap; Anoop Kumar, S.; Chandra, Amita; Dhawan, S. K.


    β-Naphthalene sulphonic acid (β-NSA) doped polyaniline (PANI)-flyash (FA) composites have been prepared by chemical oxidative polymerization route whose conductivity lies in the range 2.37-21.49 S/cm. The temperature dependence of electrical conductivity has also been recorded which shows that composites follow Mott's 3D-VRH model. SEM images demonstrate that β-NSA leads to the formation of the tubular structure with incorporated flyash phase. TGA studies show the improvement in thermal stability of composites with increase in loading level of flyash. Complex parameters i.e. permittivity (ɛ* = ɛ'- iɛ″) and permeability (μ*=μ'- iμ″) of PANI-FA composites have been calculated from experimental scattering parameters (S11 & S21) using theoretical calculations given in Nicholson-Ross and Weir algorithms. The microwave absorption properties of the composites have been studied in X-band (8.2 - 12.4 GHz) & Ku-Band (12.4 - 18 GHz) frequency range. The maximum shielding effectiveness observed was 32dB, which strongly depends on dielectric loss and volume fraction of flyash in PANI matrix.

  5. Conduction mechanism in Polyaniline-flyash composite material for shielding against electromagnetic radiation in X-band & Ku band

    Directory of Open Access Journals (Sweden)

    Avanish Pratap Singh


    Full Text Available β–Naphthalene sulphonic acid (β–NSA doped polyaniline (PANI–flyash (FA composites have been prepared by chemical oxidative polymerization route whose conductivity lies in the range 2.37–21.49 S/cm. The temperature dependence of electrical conductivity has also been recorded which shows that composites follow Mott's 3D–VRH model. SEM images demonstrate that β–NSA leads to the formation of the tubular structure with incorporated flyash phase. TGA studies show the improvement in thermal stability of composites with increase in loading level of flyash. Complex parameters i.e. permittivity (ɛ* = ɛ′- iɛ″ and permeability (μ*=μ′- iμ″ of PANI-FA composites have been calculated from experimental scattering parameters (S11 & S21 using theoretical calculations given in Nicholson–Ross and Weir algorithms. The microwave absorption properties of the composites have been studied in X-band (8.2 – 12.4 GHz & Ku–Band (12.4 – 18 GHz frequency range. The maximum shielding effectiveness observed was 32dB, which strongly depends on dielectric loss and volume fraction of flyash in PANI matrix.

  6. Electromagnetic interference shielding behaviors of Zn-based conducting oxide films prepared by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong-June; Kang, Kyung-Mun; Lee, Hong-Sub; Park, Hyung-Ho, E-mail:


    The structural, electrical, and optical properties of undoped ZnO, F-doped ZnO (ZnO:F), and Al-doped ZnO (ZnO:Al) thin films with two different thicknesses deposited by atomic layer deposition (ALD) were investigated to evaluate the electromagnetic interference shielding effectiveness (EMI-SE). A diluted fluoride hydroxide was used as a single reactant source for F doping in a ZnO matrix, and the F doping concentration was about 1 at.% in the ZnO:F films. The fabrication of the ZnO:Al films was followed by the typical ALD method, and the Al doping concentration of about 2 at.% was adjusted by the dopant deposition intervals of the ZnO:Al{sub 2}O{sub 3} precursor pulse cycle ratios, which were fixed at 19:1. The film thickness variations were controlled with 600 and 1600 total ALD cycles of approximately 100 nm and 300 nm, respectively. The carrier concentration of the films is monotonically increased in order of the undoped ZnO, ZnO:F, and ZnO:Al films. The EMI-SE values of the undoped ZnO, ZnO:F, and ZnO:Al films at 1 GHz were 0.9 dB, 2.6 dB, and 6.0 dB for ~ 100 nm, and were 2.1 dB, 9.7 dB, and 13.1 dB for ~ 300 nm, respectively. In our work, the EMI-SE value was increased by the enhancement of both the carrier concentration and film thickness due to reflection via the free carrier scattering effect. - Highlights: • Fluorine or aluminum doped ZnO thin films prepared by atomic layer deposition • Electromagnetic interference shielding effectiveness (EMI-SE) of ZnO thin films • Carrier concentration and film thickness enhanced the EMI-SE. • The enhancement of EMI-SE was due to reflection via free carrier scattering effect.

  7. Co/graphite based light weight microwave absorber for electromagnetic shielding and stealth applications (United States)

    Ansari, Azizurrahaman; Jaleel Akhtar, Mohammad


    The magnetic, thermal, thermo-mechanical, electromagnetic and microwave absorption properties of Co/graphite loaded polystyrene composites prepared by melt blending and injection molding techniques are studied in X-band (8.4–12.4 GHz) for seeking their usage as efficient light weight microwave absorbers. For profound understanding of electromagnetic absorption process at micro level, the advanced SEM and x-ray diffraction testing of the composites are carried out. The magnetic properties of the prepared Co/graphite loaded polystyrene composites are studied using the vibrating sample magnetometer. The thermal stability and thermo-mechanical properties of the prepared composites are analyzed by thermo gravimetric analysis and dynamic mechanical and thermal analysis, respectively. The complex permittivity and permeability values of the prepared composite samples in X-band of microwave frequency are extracted from the scattering data recorded during the vector network analyzer measurements. The minimum reflection loss (maximum absorption loss) of  ‑32.02 dB (99.94%) is achieved at 10.13 GHz for Co/graphite loaded polystyrene composite with the excess loading of graphite flakes for sample thickness of 1.8 mm. High absorption loss, light weight and low thickness of the proposed multicomponent Co/graphite loaded polystyrene composites make them promising candidates for electromagnetic shielding and stealth applications.

  8. A Reinforcement for Multifunctional Composites for Non-Parasitic Radiation Shielding Project (United States)

    National Aeronautics and Space Administration — Innovative lightweight radiation shielding materials are enabling to shield humans in aerospace transportation vehicles and other human habited spaces....

  9. Experimental Evaluation of a Water Shield for a Surface Power Reactor (United States)

    Pearson, J. B.; Reid, R.; Sadasivan, P.; Stewart, E.


    A water based shielding system is being investigated for use on initial lunar surface power systems. The use of water may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. A representative lunar surface reactor design is evaluated at various power levels in the Water Shield Testbed (WST) at the NASA Marshall Space Flight Center. The evaluation compares the experimental data from the WST to CFD models. Performance of a water shield on the lunar surface is predicted by CFD models anchored to test data, and by matching relevant dimensionless parameters.

  10. Vanadium based materials as electrode materials for high performance supercapacitors (United States)

    Yan, Yan; Li, Bing; Guo, Wei; Pang, Huan; Xue, Huaiguo


    As a kind of supercapacitors, pseudocapacitors have attracted wide attention in recent years. The capacitance of the electrochemical capacitors based on pseudocapacitance arises mainly from redox reactions between electrolytes and active materials. These materials usually have several oxidation states for oxidation and reduction. Many research teams have focused on the development of an alternative material for electrochemical capacitors. Many transition metal oxides have been shown to be suitable as electrode materials of electrochemical capacitors. Among them, vanadium based materials are being developed for this purpose. Vanadium based materials are known as one of the best active materials for high power/energy density electrochemical capacitors due to its outstanding specific capacitance and long cycle life, high conductivity and good electrochemical reversibility. There are different kinds of synthetic methods such as sol-gel hydrothermal/solvothermal method, template method, electrospinning method, atomic layer deposition, and electrodeposition method that have been successfully applied to prepare vanadium based electrode materials. In our review, we give an overall summary and evaluation of the recent progress in the research of vanadium based materials for electrochemical capacitors that include synthesis methods, the electrochemical performances of the electrode materials and the devices.

  11. Force Analysis of Segment for Shield Tunnel Based on Elastoplastic Damage Constitutive Model of Concrete%基于混凝土弹塑性损伤本构模型的盾构管片受力分析

    Institute of Scientific and Technical Information of China (English)

    李宇杰; 何平; 秦东平


    在混凝土弹塑性损伤本构模型的基础上,考虑盾构管片拼装块与连接螺栓的非连续性和拼装块之间的接触关系,建立三维非连续接触计算模型.以苏州某地铁盾构隧道工程为例,对盾构管片的受力状况进行模拟计算,并与惯用法模型和修正惯用法模型的计算结果进行对比分析.结果表明:盾构管片内拱顶K拼装块部分区域的损伤因子超过了损伤临界值,这些部位将产生明显可见的裂缝;盾构管片拱顶与拱底内侧的受拉区域均产生了塑性变形,拱顶K拼装块的塑性区深度达到截面宽度的55%;盾构管片最大内力组合在两侧拱腰管片的接头处;三维非连续接触计算模型可以更好地反应管片接头对内力的影响和管片混凝土材料的受力及变形特性;模型中盾构管片接头处接触单元的设置消除了其他模型中接头刚度差异对计算结果的影响,对盾构管片抗压刚度及抗弯刚度均会产生影响.%Based upon the elastoplastic damage constitutive model of concrete, considering the discontinuity between the assembly block of shield segment and connecting bolts as well as the contact relationship between each assemble block, a 3D discontinuous contact computational model was built. Taking the shield tunnel project of certain metro in Suzhou for example, 3D discontinuous contact computational model was used to simulate the force condition of shield segment. Comparative analysis was conducted between the simulated results and those obtained by routine method model and modified routine method model respectively. Results show that the damage factor of some zones on the K assembly block at the vault in shield segment has exceeded the damage threshold value, and visible cracks thus appear on these zones. Plastic deformation appears on the inner side of shield segment top and bottom subjected to tension. The plastic zone depth of the K assembly block at shield segment top has

  12. Description of Transport Codes for Space Radiation Shielding (United States)

    Kim, Myung-Hee Y.; Wilson, John W.; Cucinotta, Francis A.


    This slide presentation describes transport codes and their use for studying and designing space radiation shielding. When combined with risk projection models radiation transport codes serve as the main tool for study radiation and designing shielding. There are three criteria for assessing the accuracy of transport codes: (1) Ground-based studies with defined beams and material layouts, (2) Inter-comparison of transport code results for matched boundary conditions and (3) Comparisons to flight measurements. These three criteria have a very high degree with NASA's HZETRN/QMSFRG.

  13. 轻质石墨烯基电磁屏蔽材料的研究进展%Progress in Research on Lightweight Graphene-based EM I Shielding M aterials

    Institute of Scientific and Technical Information of China (English)

    王婵媛; 王希晰; 曹茂盛


    随着先进电子科学技术的迅速发展,电磁辐射造成的电磁污染、电磁干扰、泄密等问题已经成为电子、航天、航空、信息、通信等领域关注的重要问题,本文基于电磁屏蔽的基本理论与石墨烯的主要制备方法,针对不同的应用场合,综述了石墨烯基块体电磁屏蔽材料、泡沫电磁屏蔽材料、柔性薄层电磁屏蔽材料、高温电磁屏蔽材料4大类轻质电磁屏蔽材料的研究进展。同时,概述了石墨烯基电磁屏蔽材料的主要设计思路和制备方法,讨论了电磁屏蔽材料中的基本科学问题。基于应用发展的需求,分析了未来新型电磁屏蔽材料的发展方向和趋势,为发展设计新一代轻质高性能电磁屏蔽材料及结构提出了新的构想。%With rapid progresses on the advanced electronic science and technology ,electromagnetic irradiations have led to considerable issues ,including electromagnetic pollutions ,electromagnetic in‐terference and security concerns ,in electronics ,aeronautics ,astronautics ,information technology , communication systems and etc .Based on the fundamentals of the electromagnetic interference shiel‐ding and general methods for preparing graphene nanosheets ,this review involves the recent advances in the electromagnetic interference shielding materials of various applications in four morphologies , which include bulk ,lightweight foams ,flexible films and those for operation at high temperature . Meanwhile ,the major strategical methods and general concept for designing and fabricating graphene‐based electromagnetic interference shielding materials have been overviewed ,and fundamental issues of electromagnetic interference technology have been further discussed .The perspectives for fabrica‐ting novel electromagnetic interference shielding materials ,including ultrathin and transparent config‐uration ,and future development have been proposed based on the

  14. 盾构渣土基免烧免蒸陶粒固化重金属离子研究%Study on the Solidified Heavy Metal Ion of Shield Residues-based Unburned and Non-autoclaved Ceramsite

    Institute of Scientific and Technical Information of China (English)

    张卓; 张峰君; 谢发之; 解文杰; 丁益; 刘瑾; 刘伟


    随着城市轨道交通建设不断扩大,盾构渣土中的重金属离子浸出会造成水体污染.以盾构渣土为主要原材料,在室温下成功制得了不开裂且有一定强度的免蒸免烧陶粒.将该陶粒和纯土样进行重金属离子浸出实验,发现陶粒中5 种重金属(Zn、Cu、Pb、Hg、Cd)离子最大浸出量约为纯土样的50.0%.该方法制备的盾构渣土基陶粒较好的固化了重金属离子,可有效保障城市水质免受盾构渣土的污染.%With the continuous expansion of city rail transit construction, heavy metal ion leaching from shield residues will cause water pollution. No cracking and having certain strength of the unburned and non-autoclaved ceramsite was prepared successfully at room temperature using shield residues as the main raw material. Compared with the heavy metal ion leaching experiments of pure soil and the prepared ceramsite, the maximum leaching amount of five heavy metal ( Zn, Cu, Pb, Hg, Cd) ions for ceramsite decreased about 50.0% entirety than that of pure soil samples. This ceramsite based on shield residue had better solidified heavy metal ions and effectively guaranteed the water quality from the shield residue pollution in city.

  15. Simulation of shield tunnel construction process base on 3D discontinuous geometry model%基于三维非连续几何模型的盾构施工模拟

    Institute of Scientific and Technical Information of China (English)

    李宇杰; 何平; 秦东平; 梁英俊


    Based on the 1 # metro line of Suzhou, a 3D discontinuous geometry model about segment blocks, connecting bolts and construction process factors was built to simulate the construction process. It mainly introduces the derivation process of geometry nonlinear equations of shield tunnel excavation model, and the calculation method of shield thrust force and grouting material properties The simulate results show that, most of the area on the inside and outside surface of shield segment are in compression, some area on top and bottom position of tunnel are in tension, and the position near the connecting bolt are also in tension. Because of shield jacking force, there is a typical uplift area ahead of shield excavation face. The maximum uplift value on ground is 2.5 mm, and the distance between the maximum uplift section and shield excavation face is 8.5 m. Due to grouting material properties change with time, the ground settlement curves along tunnel ccnterline which behind shield excavation farx are ups and downs, but they finally tend to stabilize. During shield tunnel construction process, the soil which near the segment joints is obviously affected by construction, so the soil plastic area is bigger than other positions.%以苏州地铁一号线工程为研究背景,建立考虑管片分块、连接螺栓及施工过程各因素的三维非连续几何模型,对盾构法施工过程进行仿真模拟论述了盾构开挖系统模型的几何非线性方程组的推导过程,盾构顶进推力及注浆材料性质的计算方法.模拟计算结果显示:盾构管片内外侧表面大部分区域处于受压状态,拱顶与拱底部位及靠近连接螺栓的部分区域处于受拉状态;受盾构顶推力作用,盾构开挖面前方土体有一个典型的隆起区域,地表最大隆起值为2.5 mm,出现在盾构开挖面前方8.5m处;盾构开挖面后方土体沿隧道纵向的沉降受注浆材料影响随时间变化,并逐渐趋于稳定;在盾构法

  16. Analysis of tenth-value-layers for common shielding materials for a robotically mounted stereotactic radiosurgery machine. (United States)

    Rodgers, James E


    Tenth-value-layers (TVLs) for a 6 MV stereotactic radiosurgery (SRS) x-ray beam have been computed using Monte Carlo methods for radiation transport simulation. The first and equilibrium TVLs were determined in the three most common building materials used in radiation therapy vault construction: ordinary concrete, lead, and steel (iron). In contrast to broad-beam 6 MV TVL data found in the literature, the SRS TVLs can change rapidly with the size of the radiation field incident on the barrier. This research has investigated characteristics of TVLs as a function of field size (diameter) at the barrier for all materials, with special attention given to the TVL properties in iron. The x-ray spectrum used to perform these simulations was generated for the CyberKnife accelerator with the BEAMnrc Monte Carlo code. Using this spectrum as input to the MCNP5 Monte Carlo code, predicted tissue-maximum-ratio (TMR) values for a 6-cm-diameter field (at 80 cm from the target) were benchmarked against measured TMR data. The MCNP5 code was used to simulate all barrier transmissions, keeping the standard error of each data point below 1% of the mean. Results compare very well with previous measured concrete TVLs and also with published broad-beam 6 MV TVL data for all three barrier materials.

  17. Upgrading the Neutron Radiography Facility in South Africa (SANRAD): Concrete Shielding Design Characteristics (United States)

    de Beer, F. C.; Radebe, M. J.; Schillinger, B.; Nshimirimana, R.; Ramushu, M. A.; Modise, T.

    A common denominator of all neutron radiography (NRAD) facilities worldwide is that the perimeter of the experimental chamber of the facility is a radiation shielding structure which,in some cases, also includes flight tube and filter chamber structures. These chambers are normally both located on the beam port floor outside the biological shielding of the neutron source. The main function of the NRAD-shielding structure isto maintain a radiological safe working environment in the entire beam hall according to standards set by individual national radiological safety regulations. In addition, the shielding's integrity and capability should not allow, during NRAD operations, an increase in radiation levels in the beam port hall and thus negatively affectadjacent scientific facilities (e.g. neutron diffraction facilities).As a bonus, the shielding for the NRAD facility should also prevent radiation scattering towards the detector plane and doing so, thus increase thecapability of obtaining better quantitative results. This paper addresses Monte Carlo neutron-particletransport simulations to theoretically optimize the shielding capabilities of the biological barrierfor the SANRAD facility at the SAFARI-1 nuclear research reactor in South Africa. The experimental process to develop the shielding, based on the principles of the ANTARES facility, is described. After casting, the homogeneity distribution of these concrete mix materials is found to be near perfect and first order experimental radiation shielding characteristicsthrough film badge (TLD) exposure show acceptable values and trends in neutron- and gamma-ray attenuation.

  18. Comments on "A gravitational shielding based upon ZnS:Ag phosphor" and "The gravitational mass at the superconducting state"


    Woods, R. C.


    This is a discussion of two recent papers by De Aquino [physics/0112081 (2001) and physics/0201058 (2002)] that put forward an explanation of observations of gravity shielding originally reported by Podkletnov and Nieminen [Physica C 203 441 (1992)].

  19. Shielding requirements in helical tomotherapy (United States)

    Baechler, S.; Bochud, F. O.; Verellen, D.; Moeckli, R.


    Helical tomotherapy is a relatively new intensity-modulated radiation therapy (IMRT) treatment for which room shielding has to be reassessed for the following reasons. The beam-on-time needed to deliver a given target dose is increased and leads to a weekly workload of typically one order of magnitude higher than that for conventional radiation therapy. The special configuration of tomotherapy units does not allow the use of standard shielding calculation methods. A conventional linear accelerator must be shielded for primary, leakage and scatter photon radiations. For tomotherapy, primary radiation is no longer the main shielding issue since a beam stop is mounted on the gantry directly opposite the source. On the other hand, due to the longer irradiation time, the accelerator head leakage becomes a major concern. An analytical model based on geometric considerations has been developed to determine leakage radiation levels throughout the room for continuous gantry rotation. Compared to leakage radiation, scatter radiation is a minor contribution. Since tomotherapy units operate at a nominal energy of 6 MV, neutron production is negligible. This work proposes a synthetic and conservative model for calculating shielding requirements for the Hi-Art II TomoTherapy unit. Finally, the required concrete shielding thickness is given for different positions of interest.

  20. Chiral quantum dot based materials (United States)

    Govan, Joseph; Loudon, Alexander; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun'ko, Yurii


    Recently, the use of stereospecific chiral stabilising molecules has also opened another avenue of interest in the area of quantum dot (QD) research. The main goal of our research is to develop new types of technologically important quantum dot materials containing chiral defects, study their properties and explore their applications. The utilisation of chiral penicillamine stabilisers allowed the preparation of new water soluble white emitting CdS quantum nanostructures which demonstrated circular dichroism in the band-edge region of the spectrum. It was also demonstrated that all three types of QDs (D-, L-, and Rac penicillamine stabilised) show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. In this work the chiral CdS based quantum nanostructures have also been doped by copper metal ions and new chiral penicilamine stabilized CuS nanoparticles have been prepared and investigated. It was found that copper doping had a strong effect at low levels in the synthesis of chiral CdS nanostructures. We expect that this research will open new horizons in the chemistry of chiral nanomaterials and their application in biotechnology, sensing and asymmetric synthesis.

  1. An Efficient approach for Shielding Effect of the Grounding Electrodes under Impulse-Current Voltage based on MATLAB

    Directory of Open Access Journals (Sweden)

    Kalyani Pole


    Full Text Available The lightning current waveform has a major influence on the dynamic performance of ground electrodes. While high lightning current intensity improves the dynamic grounding performance due to ionization of the soil, very fast fronted pulses might worsen the performance in case of inductive behaviour. The previous analysis has often been based on quasistatic approximation that is not applicable to very fast fronted pulses. Previous Research focused on analyzing the impulse current dispersal regularity of different branches when injecting at one point. Comparing with the leakage current distribution of a single ground electrode, it is found that the leakage currents along the branches increase with the distance to the current feed point, and the more conductors near the injection point, the more uneven the leakage current distribution is. In this paper by simulation result we indicate that shielding effect should be taken into account when analyzing the impulse characteristics of grounding electrodes. Based on the simulation results, new empirical formulas applicable for slow and very fast fronted lightning current pulses are proposed. The effects of the ionization of the soil are disregarded; therefore, the new formulas are applicable for a conservative estimate of the upper bound of the impulse impedance of ground electrodes. In this paper we also analyze and compare by the MATLAB. We also provide dynamic behavior of ground electrodes.

  2. Dose reduction in computed tomography: the effect of eye and testicle shielding on radiation dose measured in patients with beryllium oxide-based optically stimulated luminescence dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Grobe, Henrik; Koch, Arne; Abolmaali, Nasreddin [Dresden University of Technology, OncoRay - Center for Radiation Research in Oncology, Molecular Imaging, Medical Faculty Carl Gustav Carus, Fetscherstrasse 74, P.O. Box 86, Dresden (Germany); Sommer, Marian; Henniger, Juergen [Dresden University of Technology, Radiation Physics Group, Institute of Nuclear and Particle Physics, Dresden (Germany); Hietschold, Volker [University Hospital Carl Gustav Carus, Institute and Policlinic of Radiological Diagnostics, Dresden (Germany)


    The aim of this study was to assess the effect of eye and testicle shielding on radiation dose to the lens and the testes of patients undergoing CT examinations. Fifty-one male patients underwent CT twice with identical protocols initially without, the second time with protective garments. Doses to the testes and the lenses were recorded with beryllium oxide-based dosimeters. The dose to the testes and lenses from CT exposure was reduced by 96.2% {+-} 1.7% and 28.2% {+-} 18.5%, when testicle and eye shielding was used, respectively. The effect of the eye shielding on the eye lens dose was found to depend on the x-ray tube position when the eye is primarily exposed during the scan. The maximum eye lens dose reduction achieved was found to be 43.2% {+-} 6.5% corresponding to the anterior position of the tube. A significant correlation between the patient's body mass index and dose exposure could not be found. Eye and testicle shields, apart from being inexpensive and easy to use, were proven to be effective in reducing eye lens and testicle radiation dose burden from CT exposures. (orig.)

  3. Optimization of the Transport Shield for Neutrinoless Double Beta-decay Enriched Germanium

    Energy Technology Data Exchange (ETDEWEB)

    Aguayo Navarrete, Estanislao; Kouzes, Richard T.; Orrell, John L.; Reid, Douglas J.; Fast, James E.


    This document presents results of an investigation of the material and geometry choice for the transport shield of germanium, the active detector material used in 76Ge neutrinoless double beta decay searches. The objective of this work is to select the optimal material and geometry to minimize cosmogenic production of radioactive isotopes in the germanium material. The design of such a shield is based on the calculation of the cosmogenic production rate of isotopes that are known to cause interfering backgrounds in 76Ge neutrinoless double beta decay searches.

  4. Compton scattering by internal shields based on melanin-containing mushrooms provides protection of gastrointestinal tract from ionizing radiation. (United States)

    Revskaya, Ekaterina; Chu, Peter; Howell, Robertha C; Schweitzer, Andrew D; Bryan, Ruth A; Harris, Matthew; Gerfen, Gary; Jiang, Zewei; Jandl, Thomas; Kim, Kami; Ting, Li-Min; Sellers, Rani S; Dadachova, Ekaterina; Casadevall, Arturo


    There is a need for radioprotectors that protect normal tissues from ionizing radiation in patients receiving high doses of radiation and during nuclear emergencies. We investigated the possibility of creating an efficient oral radioprotector based on the natural pigment melanin that would act as an internal shield and protect the tissues via Compton scattering followed by free radical scavenging. CD-1 mice were fed melanin-containing black edible mushrooms Auricularia auricila-judae before 9 Gy total body irradiation. The location of the mushrooms in the body before irradiation was determined by in vivo fluorescent imaging. Black mushrooms protected 80% of mice from the lethal dose, while control mice or those given melanin-devoid mushrooms died from gastrointestinal syndrome. The crypts of mice given black mushrooms showed less apoptosis and more cell division than those in control mice, and their white blood cell and platelet counts were restored at 45 days to preradiation levels. The role of melanin in radioprotection was proven by the fact that mice given white mushrooms supplemented with melanin survived at the same rate as mice given black mushrooms. The ability of melanin-containing mushrooms to provide remarkable protection against radiation suggests that they could be developed into oral radioprotectors.

  5. An Efficient approach for Shielding Effect of the Grounding Electrodes under Impulse-Current Voltage based on Matlab

    Directory of Open Access Journals (Sweden)

    Ms. Kalyani Pole


    Full Text Available The lightning current waveform has a majorinfluence on the dynamic performance of groundelectrodes. While high lightning current intensityimproves the dynamic grounding performance dueto ionization of the soil, very fast fronted pulsesmight worsen the performance in case of inductivebehaviour. The previous analysis has often beenbased on quasistatic approximation that is notapplicable to very fast fronted pulses. PreviousResearch focused on analyzing the impulse currentdispersal regularity of different branches wheninjecting at one point. Comparing with the leakagecurrent distribution of a single ground electrode, itis found that the leakage currents along thebranches increase with the distance to the currentfeed point, and the more conductors near theinjection point, the more uneven the leakagecurrent distribution is. In this paper by simulationresult we indicate that shielding effect should betaken into account when analyzing the impulsecharacteristics of grounding electrodes. Based onthe simulation results, new empirical formulasapplicable for slow and very fast fronted lightningcurrent pulses are proposed. The effects of theionization of the soil are disregarded; therefore, thenew formulas are applicable for a conservativeestimate of the upper bound of the impulseimpedance of ground electrodes. In this paper wealso analyze and compare by the MATLAB. We alsoprovide dynamic behavior of ground electrodes.

  6. Radiation Shielding Properties Comparison of Pb-Based Silicate, Borate, and Phosphate Glass Matrices


    Suwimon Ruengsri


    Theoretical calculations of mass attenuation coefficients, partial interactions, atomic cross-section, and effective atomic numbers of PbO-based silicate, borate, and phosphate glass systems have been investigated at 662 keV. PbO-based silicate glass has been found with the highest total mass attenuation coefficient and then phosphate and borate glasses, respectively. Compton scattering has been the dominate interaction contributed to the different total attenuation coefficients in each of th...

  7. Beta Bremsstrahlung dose in concrete shielding (United States)

    Manjunatha, H. C.; Chandrika, B. M.; Rudraswamy, B.; Sankarshan, B. M.


    In a nuclear reactor, beta nuclides are released during nuclear reactions. These betas interact with shielding concrete and produces external Bremsstrahlung (EB) radiation. To estimate Bremsstrahlung dose and shield efficiency in concrete, it is essential to know Bremsstrahlung distribution or spectra. The present work formulated a new method to evaluate the EB spectrum and hence Bremsstrahlung dose of beta nuclides (32P, 89Sr, 90Sr-90Y, 90Y, 91Y, 208Tl, 210Bi, 234Pa and 40K) in concrete. The Bremsstrahlung yield of these beta nuclides in concrete is also estimated. The Bremsstrahlung yield in concrete due to 90Sr-90Y is higher than those of other given nuclides. This estimated spectrum is accurate because it is based on more accurate modified atomic number (Zmod) and Seltzer's data, where an electron-electron interaction is also included. Presented data in concrete provide a quick and convenient reference for radiation protection. The present methodology can be used to calculate the Bremsstrahlung dose in nuclear shielding materials. It can be quickly employed to give a first pass dose estimate prior to a more detailed experimental study.

  8. Source of magma for Elet-Ozero pluton (NE Baltic Shield) - subduction or plume-related material? (United States)

    Ryabchikov, Igor; Kogarko, Liya


    Eletozero pluton is located in the northeastern part of the Karelian Craton, it covers an area of about 100 km2 and cuts through Archaean granite-gneisses. The complex has a concentric zoned structure, the peripheral part being composed of a layered gabbro series; the central area is occupied by nepheline syenites. Mafic and ultramafic rocks in this intrusion often contain potassium feldspar (olivine monzonites and monzonites). Gabbroids are characterized by rhythmic layering expressed in the alternation of leucocratic layers predominantly composed of plagioclase and melanocratic layers with pyroxenes, olivine, titanomagnetite and ilmenite. The rocks of the pluton are enriched in highly incompatible elements by comparison with moderately incompatible elements: average primitive mantle normalized La/Lu ratio is 18.3. At the same time, all the rocks from Elet-Ozero massif including the most primitive ones (high Mg-numbers and high Ni contents) exhibit distinct positive Ba anomaly: mean chondrite normalized Ba/Th ratio is 15.3 (both elements have similar incompatibility-[1]). Enrichment of parent magma in Ba is also confirmed by the presence of high-Ba feldspars and micas in some samples of gabbroids. The most Ba-rich feldspar contains 75% of celsian component: K0.09Na0.04Ca0.008Sr0.04Ba0.75Al1.73Fe0.14Si2.20O8. Ba is a fluid mobile incompatible lithophile element that is probably the most sensitive indicator of subduction fluid addition to the mantle wedge. Thus, positive Ba anomaly suggests input of subduction related component into the source of Elet-Ozero magma. The presence of subduction related material in the lithosphere of Karelian craton has been proposed on the basis of Os isotope studies of mantle xenoliths from Finnish kimberlites [2]. The age of this subduction event is similar to the age of Elet-Ozero pluton. On the other hand, there are certain arguments in favor of connection of Elet-Ozero intrusive complex with mantle plume activity. In particular it

  9. Watching a disappearing shield (United States)

    Stolarski, Richard S.


    The remote-sensing techniques used to monitor atmospheric ozone levels are reviewed, and recent results are discussed. The importance of the ozone layer as a shield for UV radiation is stressed, and the impact of human activities generating ozone-destroying compounds is considered. Ground-based, airborne, balloon-borne, and satellite remote-sensing methods are shown to complement each other to provide both global coverage and detailed structural information. Data obtained with the Nimbus-7 TOMS and solar-backscatter UV instruments are presented in graphs and briefly characterized.

  10. Nanoscale microwave microscopy using shielded cantilever probes

    KAUST Repository

    Lai, Keji


    Quantitative dielectric and conductivity mapping in the nanoscale is highly desirable for many research disciplines, but difficult to achieve through conventional transport or established microscopy techniques. Taking advantage of the micro-fabrication technology, we have developed cantilever-based near-field microwave probes with shielded structures. Sensitive microwave electronics and finite-element analysis modeling are also utilized for quantitative electrical imaging. The system is fully compatible with atomic force microscope platforms for convenient operation and easy integration of other modes and functions. The microscope is ideal for interdisciplinary research, with demonstrated examples in nano electronics, physics, material science, and biology.

  11. Evaluating Shielding Effectiveness for Reducing Space Radiation Cancer Risks (United States)

    Cucinotta, Francis A.; Kim, Myung-Hee Y.; Ren, Lei


    We discuss calculations of probability distribution functions (PDF) representing uncertainties in projecting fatal cancer risk from galactic cosmic rays (GCR) and solar particle events (SPE). The PDF s are used in significance tests of the effectiveness of potential radiation shielding approaches. Uncertainties in risk coefficients determined from epidemiology data, dose and dose-rate reduction factors, quality factors, and physics models of radiation environments are considered in models of cancer risk PDF s. Competing mortality risks and functional correlations in radiation quality factor uncertainties are treated in the calculations. We show that the cancer risk uncertainty, defined as the ratio of the 95% confidence level (CL) to the point estimate is about 4-fold for lunar and Mars mission risk projections. For short-stay lunar missions (shielding, especially for carbon composites structures with high hydrogen content. In contrast, for long duration lunar (>180 d) or Mars missions, GCR risks may exceed radiation risk limits, with 95% CL s exceeding 10% fatal risk for males and females on a Mars mission. For reducing GCR cancer risks, shielding materials are marginally effective because of the penetrating nature of GCR and secondary radiation produced in tissue by relativistic particles. At the present time, polyethylene or carbon composite shielding can not be shown to significantly reduce risk compared to aluminum shielding based on a significance test that accounts for radiobiology uncertainties in GCR risk projection.

  12. Biocompatibility of Resin-based Dental Materials


    Keyvan Moharamzadeh; Ian M. Brook; Richard van Noort


    Oral and mucosal adverse reactions to resin-based dental materials have been reported. Numerous studies have examined thebiocompatibility of restorative dental materials and their components, and a wide range of test systems for the evaluation of the biological effects of these materials have been developed. This article reviews the biological aspects of resin-based dental materials and discusses the conventional as well as the new techniques used for biocompatibility assessment of dental mat...

  13. Effective shielding to measure beam current from an ion source

    Energy Technology Data Exchange (ETDEWEB)

    Bayle, H., E-mail: [Bergoz Instrumentation, Saint-Genis-Pouilly (France); Delferrière, O.; Gobin, R.; Harrault, F.; Marroncle, J.; Senée, F.; Simon, C.; Tuske, O. [CEA, Saclay (France)


    To avoid saturation, beam current transformers must be shielded from solenoid, quad, and RFQ high stray fields. Good understanding of field distribution, shielding materials, and techniques is required. Space availability imposes compact shields along the beam pipe. This paper describes compact effective concatenated magnetic shields for IFMIF-EVEDA LIPAc LEBT and MEBT and for FAIR Proton Linac injector. They protect the ACCT Current Transformers beyond 37 mT radial external fields. Measurements made at Saclay on the SILHI source are presented.

  14. Investigation of gamma ray shielding efficiency and mechanical performances of concrete shields containing bismuth oxide as an environmentally friendly additive (United States)

    Yao, Ya; Zhang, Xiaowen; Li, Mi; Yang, Rong; Jiang, Tianjiao; Lv, Junwen


    Concrete has a proven ability to attenuate gamma rays and neutrons without compromising structural property; therefore, it is widely used as the primary shielding material in many nuclear facilities. Recently, there is a tendency toward using various additives to enhance the shielding properties of these concrete mixtures. However, most of these additives being used either pose hygiene hazards or require special handling processes. It would be ideal if environmentally friendly additives were available for use. The bismuth oxide (Bi2O3) additive shows promise in various shielding applications due to its proven radiation attenuation ability and environmentally friendly nature. To the best of our knowledge, however, Bi2O3 has never been used in concrete mixtures. Therefore, for this research, we fabricated the Bi2O3-based concrete mixtures by adding Bi2O3 powder in the ordinary concrete mixture. Concrete mixtures with lead oxide (PbO) additives were used for comparison. Radiation shielding parameters like the linear attenuation coefficients (LAC) of all these concrete mixtures showing the effects of the Bi2O3 additions are presented. The mechanical performances of concrete mixtures incorporated with Bi2O3 additive were also investigated. It suggested that the concrete mixture containing 25% Bi2O3 powder (B5 in this study) provided the best shielding capacity and mechanical performance among other mixes. It has a significant potential for application as a structural concrete where radiological protection capability is required.

  15. Long Duration Space Shelter Shielding Project (United States)

    National Aeronautics and Space Administration — Physical Sciences Inc. (PSI) has developed a ceramic composite material system that is more effective for shielding both GCR and SPE than aluminum. The composite...

  16. Experimental shielding evaluation of the radiation protection provided by the structurally significant components of residential structures. (United States)

    Dickson, E D; Hamby, D M


    The human health and environmental effects following a postulated accidental release of radioactive material to the environment have been a public and regulatory concern since the early development of nuclear technology. These postulated releases have been researched extensively to better understand the potential risks for accident mitigation and emergency planning purposes. The objective of this investigation is to provide an updated technical basis for contemporary building shielding factors for the US housing stock. Building shielding factors quantify the protection from ionising radiation provided by a certain building type. Much of the current data used to determine the quality of shielding around nuclear facilities and urban environments is based on simplistic point-kernel calculations for 1950s era suburbia and is no longer applicable to the densely populated urban environments realised today. To analyse a building's radiation shielding properties, the ideal approach would be to subject a variety of building types to various radioactive sources and measure the radiation levels in and around the building. While this is not entirely practicable, this research analyses the shielding effectiveness of ten structurally significant US housing-stock models (walls and roofs) important for shielding against ionising radiation. The experimental data are used to benchmark computational models to calculate the shielding effectiveness of various building configurations under investigation from two types of realistic environmental source terms. Various combinations of these ten shielding models can be used to develop full-scale computational housing-unit models for building shielding factor calculations representing 69.6 million housing units (61.3%) in the United States. Results produced in this investigation provide a comparison between theory and experiment behind building shielding factor methodology.

  17. The Active Muon Shield

    CERN Document Server

    Bezshyiko, Iaroslava


    In the SHiP beam-dump of the order of 1011 muons will be produced per second. An active muon-shield is used to magnetically deflect these muons out of the acceptance of the spectrom- eter. This note describes how this shield is modelled and optimized. The SHiP spectrometer is being re-optimized using a conical decay-vessel, and utilizing the possibility to magnetize part of the beam-dump shielding iron. A shield adapted to these new conditions is presented which is significantly shorter and lighter than the shield used in the Technical Proposal (TP), while showing a similar performance.

  18. Tests of shielding effectiveness of Kevlar and Nextel onboard the International Space Station and the Foton-M3 capsule. (United States)

    Pugliese, M; Bengin, V; Casolino, M; Roca, V; Zanini, A; Durante, M


    Radiation assessment and protection in space is the first step in planning future missions to the Moon and Mars, where mission and number of space travelers will increase and the protection of the geomagnetic shielding against the cosmic radiation will be absent. In this framework, the shielding effectiveness of two flexible materials, Kevlar and Nextel, were tested, which are largely used in the construction of spacecrafts. Accelerator-based tests clearly demonstrated that Kevlar is an excellent shield for heavy ions, close to polyethylene, whereas Nextel shows poor shielding characteristics. Measurements on flight performed onboard of the International Space Station and of the Foton-M3 capsule have been carried out with special attention to the neutron component; shielded and unshielded detectors (thermoluminescence dosemeters, bubble detectors) were exposed to a real radiation environment to test the shielding properties of the materials under study. The results indicate no significant effects of shielding, suggesting that thin shields in low-Earth Orbit have little effect on absorbed dose.

  19. Electron dose distributions caused by the contact-type metallic eye shield: Studies using Monte Carlo and pencil beam algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sei-Kwon; Yoon, Jai-Woong; Hwang, Taejin; Park, Soah; Cheong, Kwang-Ho; Jin Han, Tae; Kim, Haeyoung; Lee, Me-Yeon; Ju Kim, Kyoung, E-mail:; Bae, Hoonsik


    A metallic contact eye shield has sometimes been used for eyelid treatment, but dose distribution has never been reported for a patient case. This study aimed to show the shield-incorporated CT-based dose distribution using the Pinnacle system and Monte Carlo (MC) calculation for 3 patient cases. For the artifact-free CT scan, an acrylic shield machined as the same size as that of the tungsten shield was used. For the MC calculation, BEAMnrc and DOSXYZnrc were used for the 6-MeV electron beam of the Varian 21EX, in which information for the tungsten, stainless steel, and aluminum material for the eye shield was used. The same plan was generated on the Pinnacle system and both were compared. The use of the acrylic shield produced clear CT images, enabling delineation of the regions of interest, and yielded CT-based dose calculation for the metallic shield. Both the MC and the Pinnacle systems showed a similar dose distribution downstream of the eye shield, reflecting the blocking effect of the metallic eye shield. The major difference between the MC and the Pinnacle results was the target eyelid dose upstream of the shield such that the Pinnacle system underestimated the dose by 19 to 28% and 11 to 18% for the maximum and the mean doses, respectively. The pattern of dose difference between the MC and the Pinnacle systems was similar to that in the previous phantom study. In conclusion, the metallic eye shield was successfully incorporated into the CT-based planning, and the accurate dose calculation requires MC simulation.

  20. Reversibly shielded DNA polyplexes based on bioreducible PDMAEMA-SS-PEG-SS-PDMAEMA triblock copolymers mediate markedly enhanced nonviral gene transfection. (United States)

    Zhu, Caihong; Zheng, Meng; Meng, Fenghua; Mickler, Frauke Martina; Ruthardt, Nadia; Zhu, Xiulin; Zhong, Zhiyuan


    Reversibly shielded DNA polyplexes based on bioreducible poly(dimethylaminoethyl methacrylate)-SS-poly(ethylene glycol)-SS-poly(dimethylaminoethyl methacrylate) (PDMAEMA-SS-PEG-SS-PDMAEMA) triblock copolymers were designed, prepared and investigated for in vitro gene transfection. Two PDMAEMA-SS-PEG-SS-PDMAEMA copolymers with controlled compositions, 6.6-6-6.6 and 13-6-13 kDa, were obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization of dimethylaminoethyl methacrylate (DMAEMA) using CPADN-SS-PEG-SS-CPADN (CPADN: 4-cyanopentanoic acid dithionaphthalenoate; PEG: 6 kDa) as a macro-RAFT agent. Like their nonreducible PDMAEMA-PEG-PDMAEMA analogues, PDMAEMA-SS-PEG-SS-PDMAEMA triblock copolymers could effectively condense DNA into small particles with average diameters less than 120 nm and close to neutral zeta potentials (0 ∼ +6 mV) at and above an N/P ratio of 3/1. The resulting polyplexes showed excellent colloidal stability against 150 mM NaCl, which contrasts with polyplexes of 20 kDa PDMAEMA homopolymer. In the presence of 10 mM dithiothreitol (DTT), however, polyplexes of PDMAEMA-SS-PEG-SS-PDMAEMA were rapidly deshielded and unpacked, as revealed by significant increase of positive surface charges as well as increase of particle sizes to over 1000 nm. Release of DNA in response to 10 mM DTT was further confirmed by gel retardation assays. These polyplexes, either stably or reversibly shielded, revealed a low cytotoxicity (over 80% cell viability) at and below an N/P ratio of 12/1. Notably, in vitro transfection studies showed that reversibly shielded polyplexes afforded up to 28 times higher transfection efficacy as compared to stably shielded control under otherwise the same conditions. Confocal laser scanning microscope (CLSM) studies revealed that reversibly shielded polyplexes efficiently delivered and released pDNA into the perinuclei region as well as nuclei of COS-7 cells. Hence, reduction-sensitive reversibly shielded DNA

  1. Study on the Reinforcement Measures and Control Effect of the Surrounding Rock Stability Based on the Shield Tunneling Under Overpass Structure

    Directory of Open Access Journals (Sweden)

    Qian-cheng Fang


    Full Text Available To study the stability of surrounding rocks for shield tunneling under overpass structures and the safety of existing bridge structures, a practical example of the method was cited through a shield tunneling project under the overpass structure between K1+110 and K1+700 on Line 2 of Shenyang Subway, China. The sub-area reinforcement was proposed according to surrounding rock deformation characteristics during shield tunnel excavation. The bridge foundation (i.e., the clear spacing to the shield tunnel is less than 2 m was reinforced by steel support, the bridge foundation (the clear spacing is about 2~7m used “jet grouting pile” reinforcement, whereas the bridge foundation (the clear spacing is greater than 7 m did not adopt any reinforcement measures for the moment. For this study, the mean value and material heterogeneity models were established to evaluate the reinforcement effect from several aspects, such as surrounding rock deformation, plastic zone development, and safety factor. The simulation results were consistent with those of field monitoring. After reinforcement, the maximum deformation values of the surrounding rock were reduced by 4.9%, 12.2%, and 48.46%, and the maximum values of surface subsidence were decreased by 5.6%, 72.2%, and 88.64%. By contrast, the overall safety factor was increased by 4.1%, 55.46%, and 55.46%. This study posited that this reinforcement method can be adopted to solve tunnel construction problems in engineering-geological conditions effectively. References for evaluating similar projects are provided.

  2. Development of starch-based materials

    NARCIS (Netherlands)

    Habeych Narvaez, E.A.


    Starch-based materials show potential as fully degradable plastics. However, the current applicability of these materials is limited due to their poor moisture tolerance and mechanical properties. Starch is therefore frequently blended with other polymers to make the material more suitable for sp

  3. Ultra high molecular weight polyethylene (UHMWPE) fiber epoxy composite hybridized with Gadolinium and Boron nanoparticles for radiation shielding (United States)

    Mani, Venkat; Prasad, Narasimha S.; Kelkar, Ajit


    Deep space radiations pose a major threat to the astronauts and their spacecraft during long duration space exploration missions. The two sources of radiation that are of concern are the galactic cosmic radiation (GCR) and the short lived secondary neutron radiations that are generated as a result of fragmentation that occurs when GCR strikes target nuclei in a spacecraft. Energy loss, during the interaction of GCR and the shielding material, increases with the charge to mass ratio of the shielding material. Hydrogen with no neutron in its nucleus has the highest charge to mass ratio and is the element which is the most effective shield against GCR. Some of the polymers because of their higher hydrogen content also serve as radiation shield materials. Ultra High Molecular Weight Polyethylene (UHMWPE) fibers, apart from possessing radiation shielding properties by the virtue of the high hydrogen content, are known for extraordinary properties. An effective radiation shielding material is the one that will offer protection from GCR and impede the secondary neutron radiations resulting from the fragmentation process. Neutrons, which result from fragmentation, do not respond to the Coulombic interaction that shield against GCR. To prevent the deleterious effects of secondary neutrons, targets such as Gadolinium are required. In this paper, the radiation shielding studies that were carried out on the fabricated sandwich panels by vacuum-assisted resin transfer molding (VARTM) process are presented. VARTM is a manufacturing process used for making large composite structures by infusing resin into base materials formed with woven fabric or fiber using vacuum pressure. Using the VARTM process, the hybridization of Epoxy/UHMWPE composites with Gadolinium nanoparticles, Boron, and Boron carbide nanoparticles in the form of sandwich panels were successfully carried out. The preliminary results from neutron radiation tests show that greater than 99% shielding performance was

  4. Radiation Shielding for Nuclear Thermal Propulsion (United States)

    Caffrey, Jarvis A.


    Design and analysis of radiation shielding for nuclear thermal propulsion has continued at Marshall Space Flight Center. A set of optimization tools are in development, and strategies for shielding optimization will be discussed. Considerations for the concurrent design of internal and external shielding are likely required for a mass optimal shield design. The task of reducing radiation dose to crew from a nuclear engine is considered to be less challenging than the task of thermal mitigation for cryogenic propellant, especially considering the likely implementation of additional crew shielding for protection from solar particles and cosmic rays. Further consideration is thus made for the thermal effects of radiation absorption in cryogenic propellant. Materials challenges and possible methods of manufacturing are also discussed.

  5. Tissue Equivalent Proportional Counter Microdosimetry Measurements Utilized Aboard Aircraft and in Accelerator Based Space Radiation Shielding Studies (United States)

    Gersey, Brad B.; Wilkins, Richard T.


    This slide presentation reviews the Tissue Equivalent Proportional Counter (TEPC), a description of the spatially restricted LET Model, high energy proton TEPC and the results of modeling, the study of shielding and the results from the flight exposures with the TEPC.

  6. Nanoporous Silicon Based Energetic Materials (United States)


    performed at SINTEF , Norway as shown in Figure 4 (line a). 3 Annealing PSi in air at different temperatures can be used to change the surface...3h (c)PSi annealed at 500C for 0.5 h (courtesy SINTEF ) e is C d magnification bright field TEM image of PSi-Fe2O3. The inset electron...Dr. Knut Thorshaug and Dr Diplos Spyros of SINTEF Norway for DRIFTS and XPS data. REFERENCES dvanced Energetics Materials, 2004; report byA ring

  7. Mercuric Iodide Anticoincidence Shield for Gamma-Ray Spectrometer Project (United States)

    National Aeronautics and Space Administration — We propose to utilize a new detector material, polycrystalline mercuric iodide, for background suppression by active anticoincidence shielding in gamma-ray...

  8. Mercuric Iodide Anticoincidence Shield for Gamma-Ray Spectrometer Project (United States)

    National Aeronautics and Space Administration — We utilize a new detector material, polycrystalline mercuric iodide, for background suppression by active anticoincidence shielding in gamma-ray spectrometers. Two...

  9. LDEF materials special investigation group's data bases (United States)

    Strickland, John W.; Funk, Joan G.; Davis, John M.


    The Long Duration Exposure Facility (LDEF) was composed of and contained a wide array of materials, representing the largest collection of materials flown for space exposure and returned for ground-based analyses to date. The results and implications of the data from these materials are the foundation on which future space missions will be built. The LDEF Materials Special Investigation Group (MSIG) has been tasked with establishing and developing data bases to document these materials and their performance to assure not only that the data are archived for future generations but also that the data are available to the space user community in an easily accessed, user-friendly form. The format and content of the data bases developed or being developed to accomplish this task are discussed. The hardware and software requirements for each of the three data bases are discussed along with current availability of the data bases.

  10. PDMAEMA based gene delivery materials

    Directory of Open Access Journals (Sweden)

    Seema Agarwal


    Full Text Available Gene transfection is the transfer of genetic material like DNA into cells. Cationic polymers which form nanocomplexes with DNA, so-called non-viral gene vectors, are a highly promising platform for efficient gene transfection. Despite intensive research efforts and some of the on-going clinical trials on gene transfection, none of the existing cationic polymer systems are generally acceptable for human gene therapy. Since the process of gene transfection is complex and puts different challenges and demands on the delivery system, there is a strong requirement for the design and development of a multifunctional system in a simple way. This review will discuss recent efforts in design, synthesis, and performance of poly(2-dimethylaminoethyl methacrylate (PDMAEMA nanocomplexes with DNA.

  11. Materiality in a practice-based approach

    DEFF Research Database (Denmark)

    Svabo, Connie


    The paper provides an overview of the vocabulary for materiality which is used by practice-based approaches to organizational knowing. Common terms for materiality are 'artifact' and 'object'. The interaction between social and material realities is grasped as several processes: object-oriented a......The paper provides an overview of the vocabulary for materiality which is used by practice-based approaches to organizational knowing. Common terms for materiality are 'artifact' and 'object'. The interaction between social and material realities is grasped as several processes: object......-oriented activity, symbolization, embodiment, performance, alignment and mediation. Material artifacts both stabilize and destabilize organizational action. They may ensure coordination, communication, and control, but they may also create disturbance and conflict....

  12. Radiation Shielding of Lunar Regolith/Polyethylene Composites and Lunar Regolith/Water Mixtures (United States)

    Johnson, Quincy F.; Gersey, Brad; Wilkins, Richard; Zhou, Jianren


    Space radiation is a complex mixed field of ionizing radiation that can pose hazardous risks to sophisticated electronics and humans. Mission planning for lunar exploration and long duration habitat construction will face tremendous challenges of shielding against various types of space radiation in an attempt to minimize the detrimental effects it may have on materials, electronics, and humans. In late 2009, the Lunar Crater Observation and Sensing Satellite (LCROSS) discovered that water content in lunar regolith found in certain areas on the moon can be up to 5.6 +/-2.8 weight percent (wt%) [A. Colaprete, et. al., Science, Vol. 330, 463 (2010). ]. In this work, shielding studies were performed utilizing ultra high molecular weight polyethylene (UHMWPE) and aluminum, both being standard space shielding materials, simulated lunar regolith/ polyethylene composites, and simulated lunar regolith mixed with UHMWPE particles and water. Based on the LCROSS findings, radiation shielding experiments were conducted to test for shielding efficiency of regolith/UHMWPE/water mixtures with various percentages of water to compare relative shielding characteristics of these materials. One set of radiation studies were performed using the proton synchrotron at the Loma Linda Medical University where high energy protons similar to those found on the surface of the moon can be generated. A similar experimental protocol was also used at a high energy spalation neutron source at Los Alamos Neutron Science Center (LANSCE). These experiments studied the shielding efficiency against secondary neutrons, another major component of space radiation field. In both the proton and neutron studies, shielding efficiency was determined by utilizing a tissue equivalent proportional counter (TEPC) behind various thicknesses of shielding composite panels or mixture materials. Preliminary results from these studies indicated that adding 2 wt% water to regolith particles could increase shielding of

  13. New Cork-Based Materials and Applications

    Directory of Open Access Journals (Sweden)

    Luís Gil


    Full Text Available This review work is an update of a previous work reporting the new cork based materials and new applications of cork based materials. Cork is a material which has been used for multiple applications. The most known uses of cork are in stoppers (natural and agglomerated cork for alcoholic beverages, classic floor covering with composite cork tiles (made by the binding of cork particles with different binders, and thermal/acoustic/vibration insulation with expanded corkboard in buildings and some other industrial fields. Many recent developments have been made leading to new cork based materials. Most of these newly developed cork materials are not yet on the market, but they represent new possibilities for engineers, architects, designers and other professionals which must be known and considered, potentially leading to their industrialization. This paper is a review covering the last five years of innovative cork materials and applications also mentioning previous work not reported before.

  14. Whole Language-Based English Reading Materials

    Directory of Open Access Journals (Sweden)

    Dian Erlina


    Full Text Available This Research and Development (R&D aims at developing English reading materials for undergraduate EFL students of Universitas Islam Negeri (UIN Raden Fatah Palembang, Indonesia. Research data were obtained through questionnaires, tests, and documents. The results of the research show that the existing materials are not relevant to the students’ need, so there is a need for developing new materials based on whole language principles. In general, the new developed materials are considered reliable by the experts, students, and lecturers. The materials are also effective in improving students’ reading achievement. The final product of the materials consists of a course book entitled Whole Language Reading (WLR and a teacher’s manual. WLR provides rich input of reading strategies, variety of topics, concepts, texts, activities, tasks, and evaluations. Using this book makes reading more holistic and meaningful as it provides integration across language skills and subject areas. Keywords: materials development, reading materials, whole language

  15. Pollution prevention benefits of non-hazardous shielding glovebox gloves - 11000

    Energy Technology Data Exchange (ETDEWEB)

    Cournoyer, Michael E [Los Alamos National Laboratory; Dodge, Robert L [Los Alamos National Laboratory


    Radiation shielding is commonly used to protect the glovebox worker from unintentional direct and secondary radiation exposure, while working with plutonium-238 and plutonium-239. Shielding glovebox gloves are traditionally composed of lead-based materials, i.e., hazardous waste. This has prompted the development of new, non-hazardous shielding glovebox gloves. No studies, however, have investigated the pollution prevention benefits of these new glovebox gloves. We examined both leaded and non-hazardous shielding glovebox gloves. The nonhazardous substitutes are higher in cost, but this is offset by eliminating the costs associated with onsite waste handling of Resource Conservation and Recovery Act (RCRA) items. In the end, replacing lead with non-hazardous substitutes eliminates waste generation and future liability.

  16. Laboratory tests on neutron shields for gamma-ray detectors in space

    CERN Document Server

    Hong, J; Hailey, C J


    Shields capable of suppressing neutron-induced background in new classes of gamma-ray detectors such as CdZnTe are becoming important for a variety of reasons. These include a high cross section for neutron interactions in new classes of detector materials as well as the inefficient vetoing of neutron-induced background in conventional active shields. We have previously demonstrated through Monte-Carlo simulations how our new approach, supershields, is superior to the monolithic, bi-atomic neutron shields which have been developed in the past. We report here on the first prototype models for supershields based on boron and hydrogen. We verify the performance of these supershields through laboratory experiments. These experimental results, as well as measurements of conventional monolithic neutron shields, are shown to be consistent with Monte-Carlo simulations. We discuss the implications of this experiment for designs of supershields in general and their application to future hard X-ray/gamma-ray experiments...

  17. Smart window coating based on F-TiO2-KxWO3 nanocomposites with heat shielding, ultraviolet isolating, hydrophilic and photocatalytic performance (United States)

    Liu, Tongyao; Liu, Bin; Wang, Jing; Yang, Linfen; Ma, Xinlong; Li, Hao; Zhang, Yihong; Yin, Shu; Sato, Tsugio; Sekino, Tohru; Wang, Yuhua


    A series of smart window coated multifunctional NIR shielding-photocatalytic films were fabricated successfully through KxWO3 and F-TiO2 in a low-cost and environmentally friendly process. Based on the synergistic effect of KxWO3 and F-TiO2, the optimal proportion of KxWO3 to F-TiO2 was investigated and the FT/2KWO nanocomposite film exhibited strong near-infrared, ultraviolet light shielding ability, good visible light transmittance, high photocatalytic activity and excellent hydrophilic capacity. This film exhibited better thermal insulation capacity than ITO and higher photocatalytic activity than P25. Meanwhile, the excellent stability of this film was examined by the cycle photocatalytic degradation and thermal insulation experiments. Overall, this work is expected to provide a possibility in integrating KxWO3 with F-TiO2, so as to obtain a multifunctional NIR shielding-photocatalytic nanocomposite film in helping solve the energy crisis and deteriorating environmental issues.

  18. Heat Shield Paves the Way for Commercial Space (United States)


    The Phenolic-Impregnated Carbon Ablator (PICA) heat shield, a lightweight material designed to withstand high temperatures, was used for the Stardust’s reentry into Earth’s atmosphere. Hawthorne, California-based SpaceX later worked with the inventors at Ames Research Center to outfit PICA on its Dragon capsule, which is now delivering cargo to and from the International Space Station through NASA’s Commercial Resupply Services contracts program.

  19. Development of ITER shielding blanket prototype mockup by HIP bonding

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Satoshi; Furuya, Kazuyuki; Hatano, Toshihisa; Kuroda, Toshimasa; Enoeda, Mikio; Ohara, Yoshihiro [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Takatsu, Hideyuki [Japan Atomic Energy Research Inst., Office of ITER Project Promotion, Tokyo (Japan)


    minimize thermal effects on the mechanical properties and to reduce the number of fabrication steps. Based on the results of study for optimization of the simultaneous HIP bonding conditions, the HIP conditions were 1050degC, 150 MPa and holding time of 2 hours. Before this assembly for the HIP process, a deep drilling was performed for the coolant channels of the shield block from both sides of the block, then the shield block was bent by 10000-ton press machine to provide the specified curvature. During the bending, iced water was inserted into the drilled holes to prevent excessive deformation of the holes. Iced water was applied as the inserted material in this study because it was easy to remove the inserted material from the drilled holes and chemical reaction could be prevented during removal of the inserted materials. After the HIP process, the first wall surface was finally machined. The back part of the module was also machined to provide coolant manifolds, then cover plates of the manifolds were welded by TIG welding. A series of measurements and inspections was performed in the course of fabrication to make sure the dimensional accuracy and integrity of pressure boundaries. A destructive inspection was also performed with a cut specimen from the edge of the fabricated module to examine the bondability of HIPed interfaces. As a result of this fabrication experience, sufficient bonding by the single step solid HIP process has been demonstrated, and sufficient technical data base on the fabrication of the ITER shielding blanket module has been obtained. (author)

  20. Neutron shielding performance of water-extended polyester

    Energy Technology Data Exchange (ETDEWEB)

    Vega Carrillo, H.R.; Manzanares-Acuna, E.; Hernandez-Davila, V.M. [Zacatecas Univ. Autonoma, Nuclear Studies (Mexico); Vega Carrillo, H.R.; Hernandez-Davila, V.M. [Zacatecas Univ. Autonoma, Electric Engineering Academic Units (Mexico); Gallego, E.; Lorente, A. [Madrid Univ. Politecnica, cNuclear Engineering Department (Mexico)


    A Monte Carlo study to determine the shielding features to neutrons of water-extended polyester (WEP) was carried out. Materials with low atomic number are predominantly used for neutron shielding because these materials effectively attenuate neutrons, mainly through elastic and inelastic collisions. In addition to neutron attenuation properties, other desirable properties for neutron shielding materials include mechanical strength, stability, low cost, and ease of handling. During the selection of materials to design a neutron shield, prompt gamma production as well as radionuclide induced by neutron activation must be considered. In this investigation the Monte Carlo method (MCNP code) was used to evaluate the performance of a water-extended polyester shield designed for the transportation, storage, and use of a {sup 252}Cf isotopic neutron source, for comparison the calculations were extended to water shielding, the bare source in vacuum and in air. (authors)

  1. Shielding of Electronic Systems against Transient Electromagnetic Interferences

    Directory of Open Access Journals (Sweden)

    H. Herlemann


    Full Text Available In order to protect electronic systems against the effects of transient electromagnetic interferences, shields made of electrically conductive material can be used. The subject of this paper is an electrically conductive textile. When applying the shield, a reliable measure is needed in order to determine the effectiveness of the shield to protect against electromagnetic pulses. For this purpose, a time domain measurement technique is presented using double exponential pulses. With these pulses, the susceptibility of an operating electronic device with and without the shield is determined. As a criterion of quality of a shield, the breakdown failure rate found in both cases is compared.

  2. An attenuation Layer for Electromagnetic Shielding in X- Band Frequency

    Directory of Open Access Journals (Sweden)

    vida Zaroushani


    Full Text Available Uncontrolled exposure to X-band frequency leads to health damage. One of the principles of radiation protection is shielding. But, conventional shielding materials have disadvantages. Therefore, studies of novel materials, as an alternative to conventional shielding materials, are required to obtain new electromagnetic shielding material. Therefore, this study investigated the electromagnetic shielding of two component epoxy thermosetting resin for the X - band frequency with workplace approach. Two components of epoxy resin mixed according to manufacturing instruction with the weight ratio that was 100:10 .Epoxy plates fabricated in three different thicknesses (2, 4 and 6mm and shielding effectiveness measured by Vector Network Analyzer. Then, shielding effectiveness measured by the scattering parameters.The results showed that 6mm thickness of epoxy had the highest and 2mm had the lowest average of shielding effectiveness in X-band frequency that is 4.48 and 1.9 dB, respectively. Also, shielding effectiveness increased by increasing the thickness. But this increasing is useful up to 4mm. Percentage shielding effectiveness of attenuation for 6, 4 and 2mm thicknesses is 64.35%, 63.31% and 35.40%. Also, attenuation values for 4mm and 6mm thicknesses at 8.53 GHz and 8.52 GHz frequency are 77.15% and 82.95%, respectively, and can be used as favourite shields for the above frequency. 4mm-Epoxy is a suitable candidate for shielding application in X-band frequency range but, in the lower section, 6mm thickness is recommended. Finely, the shielding matrix can be used for selecting the proper thickness for electromagnetic shielding in X- Band frequency.

  3. Leaching from denture base materials in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Lygre, H.; Solheim, E.; Gjerdet, N.R. [School of Medicine, Univ. of Bergen (Norway)


    Specimens made from denture base materials were leached in Ringer Solution and in ethanol. The specimens comprised a heat-cured product processed in two different ways and two cold-cured materials. The organic compounds leaching from the specimens to the solutions were separated, identified, and quantified by a combined gas-chromatography and gas-chromatography/mass-spectrometry technique. Additives and degradation products, possibly made by free radical reactions, were released from the denture base materials. In Ringer solution only phthalates could be quantified. In ethanol solvent, biphenyl, dibutyl phthalate, dicyclohexyl phthalate, phenyl benzoate, and phenyl salicylate were quantified. In addition, copper was found in the ethanol solvent from one of the denture base materials. The amount of leachable organic compounds varies among different materials. Processing temperature influences the initial amount of leachable compounds. 36 refs., 7 figs., 1 tab.

  4. Material Recognition for Content Based Image Retrieval

    NARCIS (Netherlands)

    Geusebroek, J.M.


    One of the open problems in content-based Image Retrieval is the recognition of material present in an image. Knowledge about the set of materials present gives important semantic information about the scene under consideration. For example, detecting sand, sky, and water certainly classifies the im

  5. Materiality in a Practice-Based Approach (United States)

    Svabo, Connie


    Purpose: The paper aims to provide an overview of the vocabulary for materiality which is used by practice-based approaches to organizational knowing. Design/methodology/approach: The overview is theoretically generated and is based on the anthology Knowing in Organizations: A Practice-based Approach edited by Nicolini, Gherardi and Yanow. The…

  6. International Space Station Radiation Shielding Model Development (United States)

    Qualls, G. D.; Wilson, J. W.; Sandridge, C.; Cucinotta, F. A.; Nealy, J. E.; Heinbockel, J. H.; Hugger, C. P.; Verhage, J.; Anderson, B. M.; Atwell, W.


    The projected radiation levels within the International Space Station (ISS) have been criticized by the Aerospace Safety Advisory Panel in their report to the NASA Administrator. Methods for optimal reconfiguration and augmentation of the ISS shielding are now being developed. The initial steps are to develop reconfigurable and realistic radiation shield models of the ISS modules, develop computational procedures for the highly anisotropic radiation environment, and implement parametric and organizational optimization procedures. The targets of the redesign process are the crew quarters where the astronauts sleep and determining the effects of ISS shadow shielding of an astronaut in a spacesuit. The ISS model as developed will be reconfigurable to follow the ISS. Swapping internal equipment rack assemblies via location mapping tables will be one option for shield optimization. Lightweight shield augmentation materials will be optimally fit to crew quarter areas using parametric optimization procedures to minimize the augmentation shield mass. The optimization process is being integrated into the Intelligence Synthesis Environment s (ISE s) immersive simulation facility at the Langley Research Center and will rely on High Performance Computing and Communication (HPCC) for rapid evaluation of shield parameter gradients.

  7. Comparative Study of Tungsten and Lead as Gamma Ray Shielding Material%钨和铅作为γ射线屏蔽材料的性能对比研究

    Institute of Scientific and Technical Information of China (English)

    王建; 邹树梁


    首先通过对钨和铅的物理特性、价格、环保等方面特性进行了对比.当光子的能量为0.1、0.2、0.51、和1.25 MeV时,通过理论计算得出钨镍合金和铅在γ射线衰减10倍的情况下,分别所需两种物质的厚度,并作出对比图,其中钨镍合金是一种含钨量超过90%的钨基高比重合金,它是钨在工程应用中的主要存在形式.最后基于MCNP程序建立了常用的屏蔽模型,模拟计算结果显示理论计算的厚度都能够实现有效屏蔽.结果表明:钨作为新型的屏蔽材料具有很多的优势,对γ射线的屏蔽能力远高于铅.%This article firstly compares the tungsten and leads physical properties,price and environmental performance,then calculates the thickness of tungsten and lead with the gamma ray 10% transmission when the photon energy are 0.1 MeV,0.2 MeV,0.5,1 MeV and 1.25 MeV,and makes a comparison chart.Finally,it establishes a commonly used shielding model,through which to validate whether the thickness of theoretical calculation can achieve an effective shielding effect by MCNP program.The results showes that tungsten as a new type of shielding material has a lot of advantages,which shielding ability is far higher than the lead.Thus it provides the reference to choose the suitable shielding ma-terials in special occasions.

  8. On the morphometry of terrestrial shield volcanoes (United States)

    Grosse, Pablo; Kervyn, Matthieu


    Shield volcanoes are described as low angle edifices that have convex up topographic profiles and are built primarily by the accumulation of lava flows. This generic view of shields' morphology is based on a limited number of monogenetic shields from Iceland and Mexico, and a small set of large oceanic islands (Hawaii, Galapagos). Here, the morphometry of over 150 monogenetic and polygenetic shield volcanoes, identified inthe Global Volcanism Network database, are analysed quantitatively from 90-meter resolution DEMs using the MORVOLC algorithm. An additional set of 20 volcanoes identified as stratovolcanoes but having low slopes and being dominantly built up by accumulation of lava flows are documented for comparison. Results show that there is a large variation in shield size (volumes range from 0.1 to >1000 km3), profile shape (height/basal width ratios range from 0.01 to 0.1), flank slope gradients, elongation and summit truncation. Correlation and principal component analysis of the obtained quantitative database enables to identify 4 key morphometric descriptors: size, steepness, plan shape and truncation. Using these descriptors through clustering analysis, a new classification scheme is proposed. It highlights the control of the magma feeding system - either central, along a linear structure, or spatially diffuse - on the resulting shield volcano morphology. Genetic relationships and evolutionary trends between contrasted morphological end-members can be highlighted within this new scheme. Additional findings are that the Galapagos-type morphology with a central deep caldera and steep upper flanks are characteristic of other shields. A series of large oceanic shields have slopes systematically much steeper than the low gradients (<4-8°) generally attributed to large Hawaiian-type shields. Finally, the continuum of morphologies from flat shields to steeper complex volcanic constructs considered as stratovolcanoes calls for a revision of this oversimplified

  9. Radiation shielding for diagnostic radiology. (United States)

    Martin, Colin J


    Scattered radiation makes up the majority of the stray radiation field around an X-ray unit. The scatter is linked to the amount of radiation incident on the patient. It can be estimated from quantities used to assess patient dose such as the kerma-area product, and factors have been established linking this to levels of scattered radiation for radiography and fluoroscopy. In radiography shielding against primary radiation is also needed, but in other modalities this is negligible, as the beam is intercepted by the image receptor. In the same way scatter from CT can be quantified in terms of dose-length product, but because of higher radiation levels, exposure to tertiary scatter from ceilings needs to be considered. Transmission requirements are determined from comparisons between calculated radiation levels and agreed dose criteria, taking into account the occupancy of adjacent areas. Thicknesses of shielding material required can then be calculated from simple equations.

  10. Design of Light Multi-layered Shields for Use in Diagnostic Radiology and Nuclear Medicine via MCNP5 Monte Carlo Code


    Mehdi Zehtabian; Elham Piruzan; Zahra Molaiemanesh; Sedigheh Sina


    Introduction Lead-based shields are the most widely used attenuators in X-ray and gamma ray fields. The heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields. Materials and Methods The purpose of this study was to design multi-layered shields for protection against X-rays and gamma rays in diagnostic radiology and nuclear medicine. In this study, cubic slabs composed of several materials with high atomic numbers, i.e., lead, barium, bism...

  11. Passive Magnetic Shielding in Gradient Fields

    CERN Document Server

    Bidinosti, C P


    The effect of passive magnetic shielding on dc magnetic field gradients imposed by both external and internal sources is studied. It is found that for concentric cylindrical or spherical shells of high permeability material, higher order multipoles in the magnetic field are shielded progressively better, by a factor related to the order of the multipole. In regard to the design of internal coil systems for the generation of uniform internal fields, we show how one can take advantage of the coupling of the coils to the innermost magnetic shield to further optimize the uniformity of the field. These results demonstrate quantitatively a phenomenon that was previously well-known qualitatively: that the resultant magnetic field within a passively magnetically shielded region can be much more uniform than the applied magnetic field itself. Furthermore we provide formulae relevant to active magnetic compensation systems which attempt to stabilize the interior fields by sensing and cancelling the exterior fields clos...

  12. Overview of HZETRN and BRNTRN Space Radiation Shielding Codes (United States)

    Wilson, John W.; Cucinotta, F. A.; Shinn, J. L.; Simonsen, L. C.; Badavi, F. F.


    The NASA Radiation Health Program has supported basic research over the last decade in radiation physics to develop ionizing radiation transport codes and corresponding data bases for the protection of astronauts from galactic and solar cosmic rays on future deep space missions. The codes describe the interactions of the incident radiations with shield materials where their content is modified by the atomic and nuclear reactions through which high energy heavy ions are fragmented into less massive reaction products and reaction products are produced as radiations as direct knockout of shield constituents or produced as de-excitation products in the reactions. This defines the radiation fields to which specific devices are subjected onboard a spacecraft. Similar reactions occur in the device itself which is the initiating event for the device response. An overview of the computational procedures and data base with some applications to photonic and data processing devices will be given.

  13. Electronics based on two-dimensional materials. (United States)

    Fiori, Gianluca; Bonaccorso, Francesco; Iannaccone, Giuseppe; Palacios, Tomás; Neumaier, Daniel; Seabaugh, Alan; Banerjee, Sanjay K; Colombo, Luigi


    The compelling demand for higher performance and lower power consumption in electronic systems is the main driving force of the electronics industry's quest for devices and/or architectures based on new materials. Here, we provide a review of electronic devices based on two-dimensional materials, outlining their potential as a technological option beyond scaled complementary metal-oxide-semiconductor switches. We focus on the performance limits and advantages of these materials and associated technologies, when exploited for both digital and analog applications, focusing on the main figures of merit needed to meet industry requirements. We also discuss the use of two-dimensional materials as an enabling factor for flexible electronics and provide our perspectives on future developments.

  14. Evaluation of Personal Shields Used in Selected Radiology Departments

    Directory of Open Access Journals (Sweden)

    Mohsen Salmanvandi


    Full Text Available Introduction The purpose of this study was to evaluate personal shields in radiation departments of hospitals affiliated to Mashhad University of Medical Sciences. Materials and Methods First, the information related to 109 personal shields was recorded and evaluated by imaging equipment. Afterwards, the equivalent lead thickness (ELT of 62 personal shields was assessed, using dosimeter and standard lead layers at 100 kVp. Results In this study, 109 personal shields were assessed in terms of tears, holes and cracks. The results showed that 18 shields were damaged. Moreover, ELT was evaluated in 62 shields. As the results indicated, ELT was unacceptable in 8 personal shields and lower than expected in 9 shields. Conclusion According to the results, 16.5% of personal shields had defects (tears, holes and cracks and 13% of them were unacceptable in terms of ELT and needed to be replaced. Therefore, regular quality control of personal shields and evaluation of new shields are necessary at any radiation department.

  15. Design of Light Multi-layered Shields for Use in Diagnostic Radiology and Nuclear Medicine via MCNP5 Monte Carlo Code

    Directory of Open Access Journals (Sweden)

    Mehdi Zehtabian


    Full Text Available Introduction Lead-based shields are the most widely used attenuators in X-ray and gamma ray fields. The heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields. Materials and Methods The purpose of this study was to design multi-layered shields for protection against X-rays and gamma rays in diagnostic radiology and nuclear medicine. In this study, cubic slabs composed of several materials with high atomic numbers, i.e., lead, barium, bismuth, gadolinium, tin and tungsten, were simulated, using MCNP5 Monte Carlo code. Cubic slabs (30×30×0.05 cm3 were simulated at a 50 cm distance from the point photon source. The X-ray spectra of 80 kVp and 120 kVp were obtained, using IPEM Report 78. The photon flux following the use of each shield was obtained inside cubic tally cells (1×1×0.5 cm3 at a 5 cm distance from the shields. The photon attenuation properties of multi-layered shields (i.e., two, three, four and five layers, composed of non-lead radiation materials, were also obtained via Monte Carlo simulations. Results Among different shield designs proposed in this study, the three-layered shield, composed of tungsten, bismuth and gadolinium, showed the most significant attenuation properties in radiology, with acceptable shielding at 140 keV energy in nuclear medicine. Conclusion According to the results, materials with k-edges equal to energies common to diagnostic radiology can be proper substitutes for lead shields.

  16. Shielding high energy accelerators

    CERN Document Server

    Stevenson, Graham Roger


    After introducing the subject of shielding high energy accelerators, point source, line-of-sight models, and in particular the Moyer model. are discussed. Their use in the shielding of proton and electron accelerators is demonstrated and their limitations noted. especially in relation to shielding in the forward direction provided by large, flat walls. The limitations of reducing problems to those using it cylindrical geometry description are stressed. Finally the use of different estimators for predicting dose is discussed. It is suggested that dose calculated from track-length estimators will generally give the most satisfactory estimate. (9 refs).

  17. Experimental Evaluation of the Thermal Performance of a Water Shield for a Surface Power Reactor (United States)

    Pearson, J. Boise; Stewart, Eric T.; Reid, Robert S.


    A water based shielding system is being investigated for use on initial lunar surface power systems. The use of water may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. Natural convection in a representative lunar surface reactor shield design is evaluated at various power levels in the Water Shield Testbed (WST) at the NASA Marshall Space Flight Center. The experimental data from the WST is used to anchor a CFD model. Performance of a water shield on the lunar surface is then predicted by CFD models anchored to test data. The accompanying viewgraph presentation includes the following topics: 1) Testbed Configuration; 2) Core Heater Placement and Instrumentation; 3) Thermocouple Placement; 4) Core Thermocouple Placement; 5) Outer Tank Thermocouple Placement; 6) Integrated Testbed; 7) Methodology; 8) Experimental Results: Core Temperatures; 9) Experimental Results; Outer Tank Temperatures; 10) CFD Modeling; 11) CFD Model: Anchored to Experimental Results (1-g); 12) CFD MOdel: Prediction for 1/6-g; and 13) CFD Model: Comparison of 1-g to 1/6-g.

  18. Durability and shielding performance of borated Ceramicrete coatings in beta and gamma radiation fields

    Energy Technology Data Exchange (ETDEWEB)

    Wagh, Arun S., E-mail: [Environmental Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Sayenko, S.Yu.; Dovbnya, A.N.; Shkuropatenko, V.A.; Tarasov, R.V.; Rybka, A.V.; Zakharchenko, A.A. [National Science Center, Kharkov Institute of Physics and Technology, Kharkov (Ukraine)


    Highlights: • It incorporates all suggestions by the reviewers. • Explanation to each new term is provided and suitable references are given. • Sample identities have been streamlined by revising the text and the tables. • Some figures have been redrawn. - Abstract: Ceramicrete™, a chemically bonded phosphate ceramic, was developed for nuclear waste immobilization and nuclear radiation shielding. Ceramicrete products are fabricated by an acid–base reaction between magnesium oxide and mono potassium phosphate. Fillers are used to impart desired properties to the product. Ceramicrete’s tailored compositions have resulted in several commercial structural products, including corrosion- and fire-protection coatings. Their borated version, called Borobond™, has been studied for its neutron shielding capabilities and is being used in structures built for storage of nuclear materials. This investigation assesses the durability and shielding performance of borated Ceramicrete coatings when exposed to gamma and beta radiations to predict the composition needed for optimal shielding performance in a realistic nuclear radiation field. Investigations were conducted using experimental data coupled with predictive Monte Carlo computer model. The results show that it is possible to produce products for simultaneous shielding of all three types of nuclear radiations, viz., neutrons, gamma-, and beta-rays. Additionally, because sprayable Ceramicrete coatings exhibit excellent corrosion- and fire-protection characteristics on steel, this research also establishes an opportunity to produce thick coatings to enhance the shielding performance of corrosion and fire protection coatings for use in high radiation environment in nuclear industry.

  19. Durability and shielding performance of borated Ceramicrete coatings in beta and gamma radiation fields (United States)

    Wagh, Arun S.; Sayenko, S. Yu.; Dovbnya, A. N.; Shkuropatenko, V. A.; Tarasov, R. V.; Rybka, A. V.; Zakharchenko, A. A.


    Ceramicrete™, a chemically bonded phosphate ceramic, was developed for nuclear waste immobilization and nuclear radiation shielding. Ceramicrete products are fabricated by an acid-base reaction between magnesium oxide and mono potassium phosphate. Fillers are used to impart desired properties to the product. Ceramicrete's tailored compositions have resulted in several commercial structural products, including corrosion- and fire-protection coatings. Their borated version, called Borobond™, has been studied for its neutron shielding capabilities and is being used in structures built for storage of nuclear materials. This investigation assesses the durability and shielding performance of borated Ceramicrete coatings when exposed to gamma and beta radiations to predict the composition needed for optimal shielding performance in a realistic nuclear radiation field. Investigations were conducted using experimental data coupled with predictive Monte Carlo computer model. The results show that it is possible to produce products for simultaneous shielding of all three types of nuclear radiations, viz., neutrons, gamma-, and beta-rays. Additionally, because sprayable Ceramicrete coatings exhibit excellent corrosion- and fire-protection characteristics on steel, this research also establishes an opportunity to produce thick coatings to enhance the shielding performance of corrosion and fire protection coatings for use in high radiation environment in nuclear industry.

  20. iSHIELD - A Line Source Application of SHIELD11

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, W.R.; Rokni, S.H.; /SLAC


    iSHIELD11 performs a line-source numerical integration of radiation source terms that are defined by the iSHIELD11 computer code[1] . An example is provided to demonstrate how one can use iSHIELD11 to perform a shielding analysis for a 250 GeV electron linear accelerator.

  1. Analysis and improvement of cyclotron thallium target room shield. (United States)

    Hajiloo, N; Raisali, G; Aslani, G


    Because of high neutron and gamma-ray intensities generated during bombardment of a thallium-203 target, a thallium target-room shield and different ways of improving it have been investigated. Leakage of neutron and gamma ray dose rates at various points behind the shield are calculated by simulating the transport of neutrons and photons using the Monte Carlo N Particle transport computer code. By considering target-room geometry, its associated shield and neutron and gamma ray source strengths and spectra, three designs for enhancing shield performance have been analysed: a shielding door at the maze entrance, covering maze walls with layers of some effective materials and adding a shadow-shield in the target room in front of the radiation source. Dose calculations were carried out separately for different materials and dimensions for all the shielding scenarios considered. The shadow-shield has been demonstrated to be one suitable for neutron and gamma dose equivalent reduction. A 7.5-cm thick polyethylene shadow-shield reduces both dose equivalent rate at maze entrance door and leakage from the shield by a factor of 3.

  2. Adhesive particle shielding (United States)

    Klebanoff, Leonard Elliott; Rader, Daniel John; Walton, Christopher; Folta, James


    An efficient device for capturing fast moving particles has an adhesive particle shield that includes (i) a mounting panel and (ii) a film that is attached to the mounting panel wherein the outer surface of the film has an adhesive coating disposed thereon to capture particles contacting the outer surface. The shield can be employed to maintain a substantially particle free environment such as in photolithographic systems having critical surfaces, such as wafers, masks, and optics and in the tools used to make these components, that are sensitive to particle contamination. The shield can be portable to be positioned in hard-to-reach areas of a photolithography machine. The adhesive particle shield can incorporate cooling means to attract particles via the thermophoresis effect.

  3. A linear- and sublinear-scaling method for calculating NMR shieldings in atomic orbital-based second-order Møller-Plesset perturbation theory. (United States)

    Maurer, Marina; Ochsenfeld, Christian


    An atomic-orbital (AO) based formulation for calculating nuclear magnetic resonance chemical shieldings at the second-order Møller-Plesset perturbation theory level is introduced, which provides a basis for reducing the scaling of the computational effort with the molecular size from the fifth power to linear and for a specific nucleus to sublinear. The latter sublinear scaling in the rate-determining steps becomes possible by avoiding global perturbations with respect to the magnetic field and by solving for quantities that involve the local nuclear magnetic spin perturbation instead. For avoiding the calculation of the second-order perturbed density matrix, we extend our AO-based reformulation of the Z-vector method within a density matrix-based scheme. Our pilot implementation illustrates the fast convergence with respect to the required number of Laplace points and the asymptotic scaling behavior in the rate-determining steps.

  4. Gonad Shielding for Patients Undergoing Conventional Radiological Examinations: Is There Cause for Concern?

    Directory of Open Access Journals (Sweden)



    Full Text Available Background Gonad shielding is one of the fundamental methods by which to protect reproductive organs in patients undergoing conventional radiological examinations. A lack of or inadequate shielding of the gonads may increase the exposure of these organs and result in malignancies future generations. Objectives The aim of this study is to investigate the prevalence of gonad shielding in patients undergoing conventional radiological examinations and the availability of gonad shields and gonad shielding protocols in radiology departments. Materials and Methods A retrospective, observational cross-sectional study on the application of gonad shielding, the availability of gonad shields and the existence of gonad shielding protocols in radiology departments was performed in five different hospitals in Ahvaz, Iran. Results The highest application of gonad shielding was 6.6% for the pediatric hospital. The prevalence of gonad shielding was less than 0.2%. In 64.3% of the radiography rooms, at least one flat-contact gonad shield of a large size was available. Only large-sized gonad shields were available. Curved-contact and shadow gonad shields did not exist. Gonad shielding protocols were not existence in any of the fourteen radiography rooms investigated. Conclusions Comprehensive protection programs with on-the-job training courses for staff members are strongly recommended, as well as, the provision of radiological shields and gonad shielding protocols in radiology departments to reduce the patient’s radiation dose during radiological examinations.

  5. Reciprocity principle-based model for shielding effectiveness prediction of a rectangular cavity with a covered aperture

    Institute of Scientific and Technical Information of China (English)

    焦重庆; 李月月


    According to the reciprocity principle, we propose an efficient model to compute the shielding effectiveness of a rectangular cavity with apertures covered by conductive sheet against an external incident electromagnetic wave. This problem is converted into another problem of solving the electromagnetic field leakage from the cavity when the cavity is excited by an electric dipole placed within it. By the combination of the unperturbed cavity field and the transfer impedance of the sheet, the tangential electric field distribution on the outer surface of the sheet is obtained. Then, the field distribution is regarded as an equivalent surface magnetic current source responsible for the leakage field. The validation of this model is verified by a comparison with the circuital model and the full-wave simulations. This time-saving model can deal with arbitrary aperture shape, various wave propagation and polarization directions, and the near-field effect.

  6. Scenarios of groundwater chemical evolution in a region of the Canadian Shield based on multivariate statistical analysis

    Directory of Open Access Journals (Sweden)

    Ombeline Ghesquière


    New hydrological insights for the region: Four sample clusters were identified. Cluster 1 is composed of low-salinity Ca-HCO3 groundwater corresponding to recently infiltrated water in surface granular aquifers in recharge areas. Cluster 4 Na-(HCO3-Cl groundwater is more saline and corresponds to more evolved groundwater probably from confined bedrock aquifers. Cluster 2 and Cluster 3 (Ca-Na-HCO3 and Ca-HCO3 groundwater, respectively, correspond to mixed or intermediate water between Cluster 1 and Cluster 4 from possibly interconnected granular and bedrock aquifers. This study identifies groundwater recharge, water–rock interactions, ion exchange, solute diffusion from marine clay aquitards, saltwater intrusion and also hydraulic connections between the Canadian Shield and the granular deposits, as the main processes affecting the hydrogeochemical evolution of groundwater in the CHCN region.

  7. Microemulsion-based synthesis of nanocrystalline materials. (United States)

    Ganguli, Ashok K; Ganguly, Aparna; Vaidya, Sonalika


    Microemulsion-based synthesis is found to be a versatile route to synthesize a variety of nanomaterials. The manipulation of various components involved in the formation of a microemulsion enables one to synthesize nanomaterials with varied size and shape. In this tutorial review several aspects of microemulsion based synthesis of nanocrystalline materials have been discussed which would be of interest to a cross-section of researchers working on colloids, physical chemistry, nanoscience and materials chemistry. The review focuses on the recent developments in the above area with current understanding on the various factors that control the structure and dynamics of microemulsions which can be effectively used to manipulate the size and shape of nanocrystalline materials.

  8. Materials (United States)

    Glaessgen, Edward H.; Schoeppner, Gregory A.


    NASA Langley Research Center has successfully developed an electron beam freeform fabrication (EBF3) process, a rapid metal deposition process that works efficiently with a variety of weldable alloys. The EBF3 process can be used to build a complex, unitized part in a layer-additive fashion, although the more immediate payoff is for use as a manufacturing process for adding details to components fabricated from simplified castings and forgings or plate products. The EBF3 process produces structural metallic parts with strengths comparable to that of wrought product forms and has been demonstrated on aluminum, titanium, and nickel-based alloys to date. The EBF3 process introduces metal wire feedstock into a molten pool that is created and sustained using a focused electron beam in a vacuum environment. Operation in a vacuum ensures a clean process environment and eliminates the need for a consumable shield gas. Advanced metal manufacturing methods such as EBF3 are being explored for fabrication and repair of aerospace structures, offering potential for improvements in cost, weight, and performance to enhance mission success for aircraft, launch vehicles, and spacecraft. Near-term applications of the EBF3 process are most likely to be implemented for cost reduction and lead time reduction through addition of details onto simplified preforms (casting or forging). This is particularly attractive for components with protruding details that would require a significantly large volume of material to be machined away from an oversized forging, offering significant reductions to the buy-to-fly ratio. Future far-term applications promise improved structural efficiency through reduced weight and improved performance by exploiting the layer-additive nature of the EBF3 process to fabricate tailored unitized structures with functionally graded microstructures and compositions.

  9. Ecotoxicological effects of graphene-based materials (United States)

    Montagner, A.; Bosi, S.; Tenori, E.; Bidussi, M.; Alshatwi, A. A.; Tretiach, M.; Prato, M.; Syrgiannis, Z.


    Graphene-based materials (GBMs) are currently under careful examination due to their potential impact on health and environment. Over the last few years, ecotoxicology has started to analyze all the potential issues related to GBMs and their possible consequences on living organisms. These topics are critically considered in this comprehensive review along with some considerations about future perspectives.

  10. Morphology of polyethylene ski base materials. (United States)

    Fischer, Jörg; Wallner, Gernot M; Pieber, Alois


    We used high-resolution Raman spectroscopy and differential scanning calorimetry for a comprehensive analysis of carbon black-filled polyethylene ski base grades at processing stages from the raw material to the structured ski base. Based on Raman mapping, we assessed the applicability of an advanced evaluation procedure for amorphous, disordered, and crystalline phase fractions of polyethylene for polyethylene extrusion and sinter grades. For sinter grades, a sufficient segregation between carbon black and polyethylene was confirmed, allowing for a comprehensive Raman spectroscopic morphological analysis. Significant morphological changes in polyethylene due to processing from the raw material to the semi-finished film and to the structured ski base were identified. Throughout the processing chain, we observed a decrease in crystallinity and an increase in the amorphous phase fraction. Although the raw material and the sintered semi-finished film exhibited a different but uniform polyethylene morphology, the morphological changes due to structuring of the ski base are limited to the top surface layer. The highest amorphous phase fractions were detected in the surface of the structured ski bases.

  11. Correlated Uncertainties in Radiation Shielding Effectiveness (United States)

    Werneth, Charles M.; Maung, Khin Maung; Blattnig, Steve R.; Clowdsley, Martha S.; Townsend, Lawrence W.


    The space radiation environment is composed of energetic particles which can deliver harmful doses of radiation that may lead to acute radiation sickness, cancer, and even death for insufficiently shielded crew members. Spacecraft shielding must provide structural integrity and minimize the risk associated with radiation exposure. The risk of radiation exposure induced death (REID) is a measure of the risk of dying from cancer induced by radiation exposure. Uncertainties in the risk projection model, quality factor, and spectral fluence are folded into the calculation of the REID by sampling from probability distribution functions. Consequently, determining optimal shielding materials that reduce the REID in a statistically significant manner has been found to be difficult. In this work, the difference of the REID distributions for different materials is used to study the effect of composition on shielding effectiveness. It is shown that the use of correlated uncertainties allows for the determination of statistically significant differences between materials despite the large uncertainties in the quality factor. This is in contrast to previous methods where uncertainties have been generally treated as uncorrelated. It is concluded that the use of correlated quality factor uncertainties greatly reduces the uncertainty in the assessment of shielding effectiveness for the mitigation of radiation exposure.

  12. Neutron shielding for a {sup 252} Cf source

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R.; Manzanares A, E.; Hernandez D, V.M. [Unidades Academicas de Estudios Nucleares e Ingenieria Electrica, Universidad Autonoma de Zacatecas, C. Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Eduardo Gallego, Alfredo Lorente [Depto. de Ingenieria Nuclear, ETS Ingenieros Industriales, Universidad Politecnica de Madrid, C. Jose Gutierrez Abascal 2, 28006 Madrid (Spain)]. e-mail:


    To determine the neutron shielding features of water-extended polyester a Monte Carlo study was carried out. Materials with low atomic number are predominantly used for neutron shielding because these materials effectively attenuate neutrons, mainly through inelastic collisions and absorption reactions. During the selection of materials to design a neutron shield, prompt gamma production as well as radionuclide production induced by neutron activation must be considered. In this investigation the Monte Carlo method was used to evaluate the performance of a water-extended polyester shield designed for the transportation, storage, and use of a {sup 252}Cf isotopic neutron source. During calculations a detailed model for the {sup 252}Cf and the shield was utilized. To compare the shielding features of water extended polyester, the calculations were also made for the bare {sup 252}Cf in vacuum, air and the shield filled with water. For all cases the calculated neutron spectra was utilized to determine the ambient equivalent neutron dose at four sites around the shielding. In the case of water extended polyester and water shielding the calculations were extended to include the prompt gamma rays produced during neutron interactions, with this information the Kerma in air was calculated at the same locations where the ambient equivalent neutron dose was determined. (Author)

  13. 77 FR 67678 - Content Specifications and Shielding Evaluations for Type B Transportation Packages (United States)


    ... COMMISSION Content Specifications and Shielding Evaluations for Type B Transportation Packages AGENCY... Regulatory Issue Summary (RIS) 2012-XX, ``Content Specifications and Shielding Evaluations for Type B... Plan for Transport Packages for Radioactive Material,'' for the review of content specifications...

  14. Photodetectors based on two dimensional materials (United States)

    Zheng, Lou; Zhongzhu, Liang; Guozhen, Shen


    Two-dimensional (2D) materials with unique properties have received a great deal of attention in recent years. This family of materials has rapidly established themselves as intriguing building blocks for versatile nanoelectronic devices that offer promising potential for use in next generation optoelectronics, such as photodetectors. Furthermore, their optoelectronic performance can be adjusted by varying the number of layers. They have demonstrated excellent light absorption, enabling ultrafast and ultrasensitive detection of light in photodetectors, especially in their single-layer structure. Moreover, due to their atomic thickness, outstanding mechanical flexibility, and large breaking strength, these materials have been of great interest for use in flexible devices and strain engineering. Toward that end, several kinds of photodetectors based on 2D materials have been reported. Here, we present a review of the state-of-the-art in photodetectors based on graphene and other 2D materials, such as the graphene, transition metal dichalcogenides, and so on. Project supported by the National Natural Science Foundation of China (Nos. 61377033, 61574132, 61504136) and the State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences.

  15. The heterogeneous anti-radiation shield for spacecraft* (United States)

    Telegin, S. V.; Draganyuk, O. N.


    The paper deals with modeling of elemental composition and properties of heterogeneous layers in multilayered shields to protect spacecraft onboard equipment from radiation emitted by the natural Earth’s radiation belt. This radiation causes malfunctioning of semiconductor elements in electronic equipment and may result in a failure of the spacecraft as a whole. We consider four different shield designs and compare them to the most conventional radiation-protective material for spacecraft - aluminum. Out of light and heavy chemical elements we chose the materials with high reaction cross sections and low density. The mass attenuation coefficient of boron- containing compounds is 20% higher than that of aluminum. Heterogeneous shields consist of three layers: a glass cloth, borated material, and nickel. With a protective shield containing heavy metal the output bremsstrahlung can be reduced. The amount of gamma rays that succeed to penetrate the shield is 4 times less compared to aluminum. The shields under study have the thicknesses of 5.95 and 6.2 mm. A comparative analysis of homogeneous and multilayered protective coatings of the same chemical composition has been performed. A heterogeneous protective shield has been found to be advantageous in weight and shielding properties over its homogeneous counterparts and aluminum. The dose characteristics and transmittance were calculated by the Monte Carlo method. The results of our study lead us to conclude that a three-layer boron carbide shield provides the most effective protection from radiation. This shield ensures twice as low absorbed dose and 4 times less the number of penetrated gamma-ray photons compared to its aluminum analogue. Moreover, a heterogeneous shield will have a weight 10% lighter than aluminum, with the same attenuation coefficient of the electron flux. Such heterogeneous shields can be used to protect spacecraft launched to geostationary orbit. Furthermore, a protective boron-containing and

  16. Graphene-based materials for energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Nanda Gopal [Energy Research Institute, Nanyang Technological University (Singapore); Pan, Yongzheng; Li, Lin; Chan, Siew Hwa [School of Mechanical and Aerospace Engineering, Nanyang Technological University (Singapore)


    With the depletion of conventional energy sources, the demand for renewable energy and energy-efficient devices continues to grow. As a novel 2D nanomaterial, graphene attracts considerable research interest due to its unique properties and is a promising material for applications in energy conversion and storage devices. Recently, the fabrication of fuel cells and solar cells using graphene for various functional parts has been studied extensively. This research news summarizes and compares the advancements that have been made and are in progress in the utilization of graphene-based materials for energy conversion. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Graphene based materials for biomedical applications

    Directory of Open Access Journals (Sweden)

    Yuqi Yang


    Full Text Available Graphene, a single layer 2-dimensional structure nanomaterial with unique physicochemical properties (e.g. high surface area, excellent electrical conductivity, strong mechanical strength, unparalleled thermal conductivity, remarkable biocompatibility and ease of functionalization, has received increasing attention in physical, chemical and biomedical fields. This article selectively reviews current advances of graphene based materials for biomedical applications. In particular, graphene based biosensors for small biomolecules (glucose, dopamine etc., proteins and DNA detection have been summarized; graphene based bioimaging, drug delivery, and photothermal therapy applications have been described in detail. Future perspectives and possible challenges in this rapidly developing area are also discussed.

  18. Design and Test of a Blast Shield for Boeing 737 Overhead Compartment

    Directory of Open Access Journals (Sweden)

    Xinglai Dang


    Full Text Available This work demonstrates the feasibility of using a composite blast shield for hardening an overhead bin compartment of a commercial aircraft. If a small amount of explosive escapes detection and is brought onboard and stowed in an overhead bin compartment of a passenger aircraft, the current bins provide no protection against a blast inside the compartment. A blast from the overhead bin will certainly damage the fuselage and likely lead to catastrophic inflight structural failure. The feasibility of using an inner blast shield to harden the overhead bin compartment of a Boeing 737 aircraft to protect the fuselage skin in such a threat scenario has been demonstrated using field tests. The blast shield was constructed with composite material based on the unibody concept. The design was carried out using LS-DYNA finite element model simulations. Material panels were first designed to pass the FAA shock holing and fire tests. The finite element model included the full coupling of the overhead bin with the fuselage structure accounting for all the different structural connections. A large number of iterative simulations were carried out to optimize the fiber stacking sequence and shield thickness to minimize weight and achieve the design criterion. Three designs, the basic, thick, and thin shields, were field-tested using a frontal fuselage section of the Boeing 737–100 aircraft. The basic and thick shields protected the integrity of the fuselage skin with no skin crack. This work provides very encouraging results and useful data for optimization implementation of the blast shield design for hardening overhead compartments against the threat of small explosives.

  19. 基于MCNP安全作业舱辐射屏蔽特性研究%Performance of Shielding Gamma Radiation Based on MCNP

    Institute of Scientific and Technical Information of China (English)

    邹树梁; 孙毅成; 唐德文; 徐守龙


    采用蒙特卡罗软件MCNP5程序建立挖掘机安全作业舱及内部驾驶人员实验模型,研究在辐射源(钴-60)类型不同和源距不同的情况下,不同材料及不同结构的安全作业舱屏蔽γ射线的能力.分析讨论人体各部位剂量率值以评价安全作业舱的屏蔽效果,并依据电离辐射防护与辐射源安全基本标准( GB18871—2002)规定的工作人员的照射水平应低于0.01 mSv/h的剂量限值,确定安全作业舱结构的设计方案.此次研究为挖掘机驾驶舱屏蔽设计提供必要的研究数据和设计依据,使驾驶舱在野外高放射环境下能够有效地屏蔽酌射线,保护驾驶人员的辐射屏蔽安全.%Excavator safety chamber for work and internal driver experimental models are constructed in a Monte Carlo program MCNP5 code, and the different types of radiation source and various of sources have effect on the dose ratios of different parts of human. In different situations, the different materials and different structure of security chamber for work can also affect the ability of shielding gamma rays performance. This paper analyzes the dose ratios of every part of human body to evaluate the shielding gamma rays perform-ance of safety chamber for work. On the basis of ionizing radiation protection and radioac-tive source security basic standards (GB18871—2002),the workers exposed to gamma ra-diation should absorb the dose ratios which is less than 0 . 01 mSv/h and the structure de-sign of chamber must meet the goal to protect the drivers. The study of excavator cockpit shielding design provides essential data for further study and provides the basis of design. Above all,the study makes the cockpit with exposures to the field of high gamma radiation safe and protect the driver from gamma radiation.

  20. Evaluation of the shielding design of the fuel handling and storage system in the prototype FBR Monju

    Energy Technology Data Exchange (ETDEWEB)

    Mikami, Hisashi [Fuji Electric Co. Ltd., Kawasaki, Kanagawa (Japan); Matumiya, Hisato [Toshiba Corp., Yokohama, Kanagawa (Japan); Fujimoto, Takeshi; Tabayashi, Masao [Japan Atomic Power Co., Tokyo (Japan); Deshimaru, Takehide [Japan Nuclear Cycle Development Institute, Tsuruga, Fukui (Japan)


    Shielding performance tests of the fuel handling and storage system were carried out at Monju in October 1993. The performance of the shielding of the fresh fuel storage rack against neutron and gamma radiation from fresh fuel assemblies, that of the in-vessel fuel transfer machine (IVTM) and the ex-vessel fuel transfer machine (EVTM) against neutron and secondary gamma-rays generated in the shielding or structural materials from the neutron source assembly ({sup 252}Cf), were assessed. Dose rates were measured using rem-counters and solid-state track-detectors (SSTDs) for neutrons and ionization chamber survey-meters and film dosimeters for gamma-rays. This paper presents an outline of the measurement methods, and results, the design requirements and the design margins, which were evaluated by comparing the measurements with the calculations based on FBR shielding analysis methods. (author)

  1. Monte Carlo simulations for the space radiation superconducting shield project (SR2S) (United States)

    Vuolo, M.; Giraudo, M.; Musenich, R.; Calvelli, V.; Ambroglini, F.; Burger, W. J.; Battiston, R.


    Astronauts on deep-space long-duration missions will be exposed for long time to galactic cosmic rays (GCR) and Solar Particle Events (SPE). The exposure to space radiation could lead to both acute and late effects in the crew members and well defined countermeasures do not exist nowadays. The simplest solution given by optimized passive shielding is not able to reduce the dose deposited by GCRs below the actual dose limits, therefore other solutions, such as active shielding employing superconducting magnetic fields, are under study. In the framework of the EU FP7 SR2S Project - Space Radiation Superconducting Shield - a toroidal magnetic system based on MgB2 superconductors has been analyzed through detailed Monte Carlo simulations using Geant4 interface GRAS. Spacecraft and magnets were modeled together with a simplified mechanical structure supporting the coils. Radiation transport through magnetic fields and materials was simulated for a deep-space mission scenario, considering for the first time the effect of secondary particles produced in the passage of space radiation through the active shielding and spacecraft structures. When modeling the structures supporting the active shielding systems and the habitat, the radiation protection efficiency of the magnetic field is severely decreasing compared to the one reported in previous studies, when only the magnetic field was modeled around the crew. This is due to the large production of secondary radiation taking place in the material surrounding the habitat.

  2. Monte Carlo simulations for the space radiation superconducting shield project (SR2S). (United States)

    Vuolo, M; Giraudo, M; Musenich, R; Calvelli, V; Ambroglini, F; Burger, W J; Battiston, R


    Astronauts on deep-space long-duration missions will be exposed for long time to galactic cosmic rays (GCR) and Solar Particle Events (SPE). The exposure to space radiation could lead to both acute and late effects in the crew members and well defined countermeasures do not exist nowadays. The simplest solution given by optimized passive shielding is not able to reduce the dose deposited by GCRs below the actual dose limits, therefore other solutions, such as active shielding employing superconducting magnetic fields, are under study. In the framework of the EU FP7 SR2S Project - Space Radiation Superconducting Shield--a toroidal magnetic system based on MgB2 superconductors has been analyzed through detailed Monte Carlo simulations using Geant4 interface GRAS. Spacecraft and magnets were modeled together with a simplified mechanical structure supporting the coils. Radiation transport through magnetic fields and materials was simulated for a deep-space mission scenario, considering for the first time the effect of secondary particles produced in the passage of space radiation through the active shielding and spacecraft structures. When modeling the structures supporting the active shielding systems and the habitat, the radiation protection efficiency of the magnetic field is severely decreasing compared to the one reported in previous studies, when only the magnetic field was modeled around the crew. This is due to the large production of secondary radiation taking place in the material surrounding the habitat.

  3. Effect of incorporating carbon nanocoils on the efficiency of electromagnetic-wave shielding of carbon-nanomaterial composites (United States)

    Kang, Gi-Hwan; Kim, Sung-Hoon


    Carbon nanocoils (CNCs) were deposited on Al2O3 substrates using C2H2 and H2 as source gases in a thermal chemical vapor deposition system. Composites of CNCs in polyurethane (CNC@PU) and CNCs plus other carbon-based materials, such as carbon microcoils (CMCs) and carbon nanotubes (CNTs), in polyurethane (CNC + CMC@PU, CNC + CNT@PU) was fabricated. The electromagnetic-wave-shielding effectiveness of the CNCs-incorporated composites were examined and compared with those of other carbon-based materials in the measurement-frequency range of 0.25-4.0 GHz. The incorporation of CNCs in CMC@PU composites reduced the shielding effectiveness; on the other hand, it slightly enhanced the shielding effectiveness of CNT@PU composites within the measurement frequency range of 0.5-3.0 GHz. Based on the resulting shielding effectiveness, we conclude that the incorporation of CNCs was useful for the materials that exhibited reflection-based shielding effectiveness although the CNCs themselves had poor electrical conductivity.

  4. Evaluation of Spacecraft Shielding Effectiveness for Radiation Protection (United States)

    Cucinotta, Francis A.; Wilson, John W.


    The potential for serious health risks from solar particle events (SPE) and galactic cosmic rays (GCR) is a critical issue in the NASA strategic plan for the Human Exploration and Development of Space (HEDS). The excess cost to protect against the GCR and SPE due to current uncertainties in radiation transmission properties and cancer biology could be exceedingly large based on the excess launch costs to shield against uncertainties. The development of advanced shielding concepts is an important risk mitigation area with the potential to significantly reduce risk below conventional mission designs. A key issue in spacecraft material selection is the understanding of nuclear reactions on the transmission properties of materials. High-energy nuclear particles undergo nuclear reactions in passing through materials and tissue altering their composition and producing new radiation types. Spacecraft and planetary habitat designers can utilize radiation transport codes to identify optimal materials for lowering exposures and to optimize spacecraft design to reduce astronaut exposures. To reach these objectives will require providing design engineers with accurate data bases and computationally efficient software for describing the transmission properties of space radiation in materials. Our program will reduce the uncertainty in the transmission properties of space radiation by improving the theoretical description of nuclear reactions and radiation transport, and provide accurate physical descriptions of the track structure of microscopic energy deposition.

  5. Gas sensors based on nanostructured materials. (United States)

    Jiménez-Cadena, Giselle; Riu, Jordi; Rius, F Xavier


    Gas detection is important for controlling industrial and vehicle emissions, household security and environmental monitoring. In recent decades many devices have been developed for detecting CO(2), CO, SO(2), O(2), O(3), H(2), Ar, N(2), NH(3), H(2)O and several organic vapours. However, the low selectivity or the high operation temperatures required when most gas sensors are used have prompted the study of new materials and the new properties that come about from using traditional materials in a nanostructured mode. In this paper, we have reviewed the main research studies that have been made of gas sensors that use nanomaterials. The main quality characteristics of these new sensing devices have enabled us to make a critical review of the possible advantages and drawbacks of these nanostructured material-based sensors.

  6. Environmental assessment of biomass based materials

    DEFF Research Database (Denmark)

    Jørgensen, Susanne Vedel

    non-standard impacts from land use and land use change (LULUC) Some of the impacts associated with LULUC for biomass production, which are often not addressed in LCAs have been addressed through a theoretic case study in this PhD project. These impacts are changes in surface albedo, biogenic carbon...... with temporary carbon storage in biomaterials, in a way that quantifies the potential climate change benefit in relation to avoiding crossing near-term climatic targets. The geographical scope in this PhD project is global, as the focus is on methodology development and assessment of biomaterials at a global...... materials. Background The society today is highly dependent on fossil oil and gas for producing fuels, chemicals and materials, however many of those can alternatively be produced from biomass. The potential of biomaterials to substitute fossil based materials receives increased attention, and their global...

  7. Satellite Contamination and Materials Outgassing Knowledge base (United States)

    Minor, Jody L.; Kauffman, William J. (Technical Monitor)


    Satellite contamination continues to be a design problem that engineers must take into account when developing new satellites. To help with this issue, NASA's Space Environments and Effects (SEE) Program funded the development of the Satellite Contamination and Materials Outgassing Knowledge base. This engineering tool brings together in one location information about the outgassing properties of aerospace materials based upon ground-testing data, the effects of outgassing that has been observed during flight and measurements of the contamination environment by on-orbit instruments. The knowledge base contains information using the ASTM Standard E- 1559 and also consolidates data from missions using quartz-crystal microbalances (QCM's). The data contained in the knowledge base was shared with NASA by government agencies and industry in the US and international space agencies as well. The term 'knowledgebase' was used because so much information and capability was brought together in one comprehensive engineering design tool. It is the SEE Program's intent to continually add additional material contamination data as it becomes available - creating a dynamic tool whose value to the user is ever increasing. The SEE Program firmly believes that NASA, and ultimately the entire contamination user community, will greatly benefit from this new engineering tool and highly encourages the community to not only use the tool but add data to it as well.

  8. Adsorption of Si6O12 on CNTs in view point of NMR shielding tensors and NBO analysis: A novel material for drug delivery

    Directory of Open Access Journals (Sweden)

    Zahra Barmaki


    Full Text Available The interaction of the Si6O12 molecule over the CNTs have been investigated with density functional theory using HF and B3LYP method and 6-31G, 6-31G** and 6-311G** basis sets. We also analyze the electronic structure and charge Mulliken population for the energetically most favorable complexes. Our results indicate Si6O12 can form stable bindings with CNTs via the Oxygen. The NMR shielding tensors have been investigated. The same Study performed for Si7O14 and we found that this molecule can form stable bindings with CNTs via the Silicon site. Thus, we arrive at the prediction that the even number (Si6O6 has a different mechanism for adding to CNTs compare to add number such as Si7O14.

  9. Radiation Shielding for Manned Deep Space Missions (United States)

    Adams, James H., Jr.


    The arrival of the Expedition 1 Crew at the International Space Station represents the beginning of the continuous presence of man in space. Already we are deploying astronauts and cosmonauts for missions of approx. 6 months onboard the ISS. In the future we can anticipate that more people will be in space and they will be there for longer periods. Even with 6-months deployments to the ISS, the radiation exposure that crew members receive is approaching the exposure limits imposed by the governments of the space- faring nations. In the future we can expect radiation protection to be a dominant consideration for long manned missions. Recognizing this, NASA has expanded their research program on radiation health. This program has three components, bioastronautics, fundamental biology and radiation shielding materials. Bioastronautics is concerned with the investigating the effects of radiation on humans. Fundamental biology investigates the basic mechanisms of radiation damage to tissue. Radiation shielding materials research focuses on developing accurate computational tools to predict the radiation shielding effectiveness of materials. It also investigates new materials that can be used for spacecraft. The radiation shielding materials program will be described and examples of results from the ongoing research will be shown.

  10. General Corrosion and Localized Corrosion of the Drip Shield

    Energy Technology Data Exchange (ETDEWEB)

    F. Hua


    The repository design includes a drip shield (BSC 2004 [DIRS 168489]) that provides protection for the waste package both as a barrier to seepage water contact and a physical barrier to potential rockfall. The purpose of the process-level models developed in this report is to model dry oxidation, general corrosion, and localized corrosion of the drip shield plate material, which is made of Ti Grade 7. This document is prepared according to ''Technical Work Plan For: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The models developed in this report are used by the waste package degradation analyses for TSPA-LA and serve as a basis to determine the performance of the drip shield. The drip shield may suffer from other forms of failure such as the hydrogen induced cracking (HIC) or stress corrosion cracking (SCC), or both. Stress corrosion cracking of the drip shield material is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]). Hydrogen induced cracking of the drip shield material is discussed in ''Hydrogen Induced Cracking of Drip Shield'' (BSC 2004 [DIRS 169847]).

  11. Preliminary review of Precambrian Shield rocks for potential waste repository

    Energy Technology Data Exchange (ETDEWEB)

    Yardley, D.H.; Goldich, S.S.


    This review of the Canadian Shield is primarily concerned with the part (such as in the Lake Superior region) that is seismically the least active of the North American continent. The crystalline metamorphic and igneous rocks of the more stable elements of the shield provide excellent possibilities for dry excavations suitable for long-term storage of radioactive waste materials. (DLC)

  12. Shielding superconductors with thin films

    CERN Document Server

    Posen, Sam; Catelani, Gianluigi; Liepe, Matthias U; Sethna, James P


    Determining the optimal arrangement of superconducting layers to withstand large amplitude AC magnetic fields is important for certain applications such as superconducting radiofrequency cavities. In this paper, we evaluate the shielding potential of the superconducting film/insulating film/superconductor (SIS') structure, a configuration that could provide benefits in screening large AC magnetic fields. After establishing that for high frequency magnetic fields, flux penetration must be avoided, the superheating field of the structure is calculated in the London limit both numerically and, for thin films, analytically. For intermediate film thicknesses and realistic material parameters we also solve numerically the Ginzburg-Landau equations. It is shown that a small enhancement of the superheating field is possible, on the order of a few percent, for the SIS' structure relative to a bulk superconductor of the film material, if the materials and thicknesses are chosen appropriately.

  13. Plasmonic-Field Interactions at Nanoparticle Interfaces for Infrared Thermal-Shielding Applications Based on Transparent Oxide Semiconductors. (United States)

    Matsui, Hiroaki; Furuta, Shinya; Hasebe, Takayuki; Tabata, Hitoshi


    This paper describes infrared plasmonic responses in three-dimensional (3D) assembled films of In2O3:Sn nanoparticles (NPs). The introduction of surface modifications to NPs can facilitate the production of electric-field interactions between NPs due to the creation of narrow crevices in the NP interfaces. In particular, the electric-field interactions along the in-plane and out-of-plane directions in the 3D assembled NP films allow for resonant splitting of plasmon excitations to the quadrupole and dipole modes, thereby realizing selective high reflections in the near- and mid-infrared range, respectively. The origins of these plasmonic properties were revealed from electric-field distributions calculated by electrodynamic simulations that agreed well with experimental results. The interparticle gaps and their derived plasmon couplings play an important role in producing high reflective performances in assembled NP films. These 3D assemblies of NPs can be further extended to produce large-size flexible films with high infrared reflectance, which simultaneously exhibit microwave transmittance essential for telecommunications. This study provides important insights for harnessing infrared optical responses using plasmonic technology for the fabrication of infrared thermal-shielding applications.

  14. RadShield: semiautomated shielding design using a floor plan driven graphical user interface. (United States)

    DeLorenzo, Matthew C; Wu, Dee H; Yang, Kai; Rutel, Isaac B


    The purpose of this study was to introduce and describe the development of RadShield, a Java-based graphical user interface (GUI), which provides a base design that uniquely performs thorough, spatially distributed calculations at many points and reports the maximum air-kerma rate and barrier thickness for each barrier pursuant to NCRP Report 147 methodology. Semiautomated shielding design calculations are validated by two approaches: a geometry-based approach and a manual approach. A series of geometry-based equations were derived giving the maximum air-kerma rate magnitude and location through a first derivative root finding approach. The second approach consisted of comparing RadShield results with those found by manual shielding design by an American Board of Radiology (ABR)-certified medical physicist for two clinical room situations: two adjacent catheterization labs, and a radiographic and fluoroscopic (R&F) exam room. RadShield's efficacy in finding the maximum air-kerma rate was compared against the geometry-based approach and the overall shielding recommendations by RadShield were compared against the medical physicist's shielding results. Percentage errors between the geometry-based approach and RadShield's approach in finding the magnitude and location of the maximum air-kerma rate was within 0.00124% and 14 mm. RadShield's barrier thickness calculations were found to be within 0.156 mm lead (Pb) and 0.150 mm lead (Pb) for the adjacent catheterization labs and R&F room examples, respectively. However, within the R&F room example, differences in locating the most sensitive calculation point on the floor plan for one of the barriers was not considered in the medical physicist's calculation and was revealed by the RadShield calculations. RadShield is shown to accurately find the maximum values of air-kerma rate and barrier thickness using NCRP Report 147 methodology. Visual inspection alone of the 2D X-ray exam distribution by a medical physicist may not

  15. Weight Assessment for Fuselage Shielding on Aircraft With Open-Rotor Engines and Composite Blade Loss (United States)

    Carney, Kelly; Pereira, Michael; Kohlman, Lee; Goldberg, Robert; Envia, Edmane; Lawrence, Charles; Roberts, Gary; Emmerling, William


    The Federal Aviation Administration (FAA) has been engaged in discussions with airframe and engine manufacturers concerning regulations that would apply to new technology fuel efficient "openrotor" engines. Existing regulations for the engines and airframe did not envision features of these engines that include eliminating the fan blade containment systems and including two rows of counter-rotating blades. Damage to the airframe from a failed blade could potentially be catastrophic. Therefore the feasibility of using aircraft fuselage shielding was investigated. In order to establish the feasibility of this shielding, a study was conducted to provide an estimate for the fuselage shielding weight required to provide protection from an open-rotor blade loss. This estimate was generated using a two-step procedure. First, a trajectory analysis was performed to determine the blade orientation and velocity at the point of impact with the fuselage. The trajectory analysis also showed that a blade dispersion angle of 3deg bounded the probable dispersion pattern and so was used for the weight estimate. Next, a finite element impact analysis was performed to determine the required shielding thickness to prevent fuselage penetration. The impact analysis was conducted using an FAA-provided composite blade geometry. The fuselage geometry was based on a medium-sized passenger composite airframe. In the analysis, both the blade and fuselage were assumed to be constructed from a T700S/PR520 triaxially-braided composite architecture. Sufficient test data on T700S/PR520 is available to enable reliable analysis, and also demonstrate its good impact resistance properties. This system was also used in modeling the surrogate blade. The estimated additional weight required for fuselage shielding for a wing- mounted counterrotating open-rotor blade is 236 lb per aircraft. This estimate is based on the shielding material serving the dual use of shielding and fuselage structure. If the

  16. In-beam background suppression shield

    DEFF Research Database (Denmark)

    Santoro, V.; Cai, Xiao Xiao; DiJulio, D. D.


    , which do not use a bender to help mitigate the fast neutron background, are the most challenging. For these beam lines we propose the innovative shielding of placing blocks of material directly into the guide system, which allow a minimum attenuation of the cold and thermal fluxes relative...

  17. Multilayer passive shielding of scintillation detectors based on BGO, NaI(Tl), and stilbene crystals operating in intense neutron fields with an energy of 14.1 MeV (United States)

    Bystritsky, V. M.; Valkovic, V.; Grozdanov, D. N.; Zontikov, A. O.; Ivanov, I. Zh.; Kopatch, Yu. N.; Krylov, A. R.; Rogov, Yu. N.; Ruskov, I. N.; Sapozhnikov, M. G.; Skoy, V. R.; Shvetsov, V. N.


    We discuss the issues related to choosing the optimum type of passive shielding of scintillation detectors based on BGO, NaI(Tl), and stilbene crystals from the direct penetration of neutron radiation with an energy of 14.1 MeV that was emitted isotropically into a solid angle of 4π. A series of experimental measurements of the count-rate suppression factor that may be obtained for the indicated detectors through the use of various shielding filters comprising iron, lead, and borated polyethylene layers with a total thickness not exceeding 50 cm are conducted.

  18. Magnetic Shielding Method and Experiment Study of Inertial Measurement Unit Based on High Precision Fiber-optic Gyroscope%高精度光纤IMU的磁屏蔽方法及实验研究

    Institute of Scientific and Technical Information of China (English)

    李金涛; 房建成


    惯性测量单元(IMU)是位置姿态系统(POS)的核心部分,IMU的精度很大程度上决定着POS精度.由于高精度光纤陀螺(FOG)的光纤线圈对磁场敏感,基于高精度FOG的IMU精度会受磁场影响而降低.本文研究了FOG磁敏感性机理,通过实验得出高精度光纤IMU对磁场敏感的结论.采用电磁场有限元分析软件Ansoft Maxwell研究了磁屏蔽体采用不同材料、不同厚度时的磁屏蔽效能(SE),并进行了IMU磁屏蔽结构设计.通过亥姆霍兹线圈测试得到的磁屏蔽体实际屏蔽效能最高为48.20 dB,与有限元分析结果基本一致.转台环境测试表明:屏蔽体使FOG漂移减小到9%以上;亥姆霍兹线圈测试表明:通过磁屏蔽使FOG零偏磁敏感度衰减2~21 dB,漂移磁敏感度衰减9~23 dB,对提高光纤IMU测试和应用精度以及机载环境适应性有重要意义.%The inertial measurement unit (IMU) is the core of a position and orientation system (POS), whose accuracy has a crucial impact on POS accuracy. But the IMU accuracy based on high precision fiber-optic gyroscope (FOG) is degraded because of the sensitivity of the FOG fiber coil to the magnetic field. This paper studied the magnetic sensitivity mechanism of the FOG. And through experimental study reached the conclusion that the IMU based on a high precision FOG is also sensitive to the magnetic field. An IMU shielding is designed, and its shielding effectiveness (SE) is analyzed by electromagnetic field finite element analysis software Ansoft Maxwell for different materials with different thicknesses. The best SE of 48.20 Db is achieved with a Helmholtz coil test, which is consistent with the results of the finite element analysis. The turn table test shows that a reduction of over 9% of the FOG drift is achieved with the enclosure. The Helmholtz coil test with magnetic shielding demonstrates that the bias and drift magnetic sensitivity of the FOG are decreased by 2-21 Db and 9-23 Db

  19. A new model for the growth of basaltic shields based on deformation of Fernandina volcano, Galápagos Islands (United States)

    Bagnardi, Marco; Amelung, Falk; Poland, Michael P.


    Space-geodetic measurements of surface deformation produced by the most recent eruptions at Fernandina – the most frequently erupting volcano in the Galápagos Archipelago – reveal that all have initiated with the intrusion of subhorizontal sills from a shallow magma reservoir. This includes eruptions from fissures that are oriented both radially and circumferentially with respect to the summit caldera. A Synthetic Aperture Radar (SAR) image acquired 1–2 h before the start of a radial fissure eruption in 2009 captures one of these sills in the midst of its propagation toward the surface. Galápagos eruptive fissures of all orientations have previously been presumed to be fed by vertical dikes, and this assumption has guided models of the origin of the eruptive fissure geometry and overall development of the volcanoes. Our findings allow us to reinterpret the internal structure and evolution of Galápagos volcanoes and of similar basaltic shields. Furthermore, we note that stress changes generated by the emplacement of subhorizontal sills feeding one type of eruption may control the geometry of subsequent eruptive fissures. Specifically, circumferential fissures tend to open within areas uplifted by sill intrusions that initiated previous radial fissure eruptions. This mechanism provides a possible explanation for the pattern of eruptive fissures that characterizes all the western Galápagos volcanoes, as well as the alternation between radial and circumferential fissure eruptions at Fernandina. The same model suggests that the next eruption of Fernandina will be from a circumferential fissure in the area uplifted by the 2009 sill intrusion, just southwest of the caldera rim.

  20. Mathematical model of thermal shields for long-term stability optical resonators

    CERN Document Server

    Sanjuan, Josep; Braxmaier, Claus


    Modern experiments aiming at tests of fundamental physics, like measuring gravitational waves or testing Lorentz Invariance with unprecedented accuracy, require thermal environments that are highly stable over long times. To achieve such a stability, the experiment including typically an optical resonator is nested in a thermal enclosure, which passively attenuates external temperature fluctuations to acceptable levels. These thermal shields are usually designed using tedious numerical simulations or with simple analytical models. In this paper, we propose an accurate analytical method to estimate the performance of passive thermal shields in the frequency domain, which allows for fast evaluation and optimization. The model analysis has also unveil interesting properties of the shields, such as dips in the transfer function for some frequencies under certain combinations of materials and geometries. We validate the results by comparing them to numerical simulations performed with commercial software based on ...

  1. Bibliographic data base for low activation materials

    Energy Technology Data Exchange (ETDEWEB)

    Alenina, M.V.; Kolotov, V.P. [Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow (Russian Federation); Ivanov, L.I. [A.A. Baikov Institute of Metallurgy and Science of Materials, Russian Academy of Sciences, Moscow (Russian Federation)


    Full text of publication follows: The analysis of the publications dealing with development of low-activation materials for fusion technology demonstrates that the period of information doubling is about 5-6 years. Such high rate usually is characteristic of the actively developing field of science. To develop an useful instrument for analysis and systematization of the available data a computer based bibliographic system has been developed some time ago. Recently the engine of the system has been significantly modernized. The bibliographic system is based on using of MS SQL server data base which includes main bibliographic information including abstracts. The most important feature of the system is that full-text abstracts searching capabilities are appended with indexing of information by experts to increase its definition. The experts indexes cover the following topics: - Main problems; - Software and methods for calculation; - Libraries of nuclear data; - Spectrum of neutrons for different construction parts of fusion reactor; - Low activation materials; - Technology of production; - Radiation effects; - Utilization of radiation waste; - Estimation of risks; - Designs of fusion reactor; - Nuclear transmutations; - Equipment used for investigations. The primary data base is filling/appending by periodical queries to different bibliographic data bases (INIS, COMPEMDEX and others) via suitable Internet providers including strict analysis of the income information to remove a possible 'information noise' and following data indexing by experts. The data base contains references since 1976 year (when first works in this area have been fulfilled) and until now. The bibliographic system is accessible by means of Internet using different forms developed for queries ({approx}lam{sub d}b). (authors)

  2. Electromagnetic interference shielding with 2D transition metal carbides (MXenes) (United States)

    Shahzad, Faisal; Alhabeb, Mohamed; Hatter, Christine B.; Anasori, Babak; Man Hong, Soon; Koo, Chong Min; Gogotsi, Yury


    Materials with good flexibility and high conductivity that can provide electromagnetic interference (EMI) shielding with minimal thickness are highly desirable, especially if they can be easily processed into films. Two-dimensional metal carbides and nitrides, known as MXenes, combine metallic conductivity and hydrophilic surfaces. Here, we demonstrate the potential of several MXenes and their polymer composites for EMI shielding. A 45-micrometer-thick Ti3C2Tx film exhibited EMI shielding effectiveness of 92 decibels (>50 decibels for a 2.5-micrometer film), which is the highest among synthetic materials of comparable thickness produced to date. This performance originates from the excellent electrical conductivity of Ti3C2Tx films (4600 Siemens per centimeter) and multiple internal reflections from Ti3C2Tx flakes in free-standing films. The mechanical flexibility and easy coating capability offered by MXenes and their composites enable them to shield surfaces of any shape while providing high EMI shielding efficiency.

  3. EURISOL-DS multi-MW target unit: Neutronics performance and shielding assessment, dose rate and material activation calculations for the MAFF configuration

    CERN Document Server

    Romanets, Y; Kadi, Y; Luis, R; Goncalves, I F; Tecchio, L; Kharoua, C; Vaz, P; Ene, D; David, J C; Rocca, R; Negoita, F


    One of the objectives of the EURISOL (EURopean Isotope Separation On-Line Radioactive Ion Beam) Design Study consisted of providing a safe and reliable facility layout and design for the following operational parameters and characteristics: (a) a 4 MW proton beam of 1 GeV energy impinging on a mercury target (the converter); (b) high neutron fluxes (similar to 3 x 10(16) neutrons/s) generated by spallation reactions of the protons impinging in the converter and (c) fission rate on fissile U-235 targets in excess of 10(15) fissions/s. In this work, the state-of-the-art Monte Carlo codes MCNPX (Pelowitz, 2005) and FLUKA (Vlachoudis, 2009; Ferrari et al., 2008) were used to characterize the neutronics performance and to perform the shielding assessment (Herrera-Martinez and Kadi, 2006; Cornell, 2003) of the EURISOLTarget Unit and to provide estimations of dose rate and activation of different components, in view of the radiation safety assessment of the facility. Dosimetry and activation calculations were perfor...

  4. A New Bio-based Dielectric Material. (United States)

    Zhan, Mingjiang; Wool, Richard P.


    Low dielectric constant (low-k) materials are widely used in modern high-speed microelectronics, such as printed circuit boards. A new bio-based composite was developed from soybean oil and chicken feather fibers, which has the potential to replace currently used petroleum-based dielectrics. Feather fibers have a unique hollow structure which distinguishes them from glass fibers and give very attractive properties. Due to the retained air in the hollow fibers, the dielectric constant can be lower than conventional epoxy-based dielectrics at both low and high frequencies. The coefficients of thermal expansion (CTE) of the materials decrease with addition of feather fibers and even can be negative. By controlling the fraction of fibers, delamination caused by CTE mismatch between the dielectric and the metal lines can be avoided. The enhancement of adhesion between copper surface and polymer matrix was investigated. The tough structure of fibers significantly improved the mechanical properties of the composites, such as flexural properties and storage modulus. Supported by USDA

  5. Hinged Shields for Machine Tools (United States)

    Lallande, J. B.; Poland, W. W.; Tull, S.


    Flaps guard against flying chips, but fold away for tool setup. Clear plastic shield in position to intercept flying chips from machine tool and retracted to give operator access to workpiece. Machine shops readily make such shields for own use.

  6. Accelerator shielding experts meet at CERN

    CERN Multimedia

    CERN Bulletin


    Fifteen years after its first CERN edition, the Shielding Aspects of Accelerator, Targets and Irradiation Facility (SATIF) conference was held again here from 2-4 June. Now at its 10th edition, SATIF10 brought together experts from all over the world to discuss issues related to the shielding techniques. They set out the scene for an improved collaboration and discussed novel shielding solutions.   This was the most attended meeting of the series with more than 65 participants from 34 institutions and 14 countries. “We welcomed experts from many different laboratories around the world. We come from different contexts but we face similar problems. In this year’s session, among other things, we discussed ways for improving the effectiveness of calculations versus real data, as well as experimental solutions to investigate the damage that radiation produces on various materials and the electronics”, says Marco Silari, Chair of the conference and member of the DGS/RP gro...

  7. Electronics Shielding and Reliability Design Tools (United States)

    Wilson, John W.; ONeill, P. M.; Zang, Thomas A., Jr.; Pandolf, John E.; Koontz, Steven L.; Boeder, P.; Reddell, B.; Pankop, C.


    It is well known that electronics placement in large-scale human-rated systems provides opportunity to optimize electronics shielding through materials choice and geometric arrangement. For example, several hundred single event upsets (SEUs) occur within the Shuttle avionic computers during a typical mission. An order of magnitude larger SEU rate would occur without careful placement in the Shuttle design. These results used basic physics models (linear energy transfer (LET), track structure, Auger recombination) combined with limited SEU cross section measurements allowing accurate evaluation of target fragment contributions to Shuttle avionics memory upsets. Electronics shielding design on human-rated systems provides opportunity to minimize radiation impact on critical and non-critical electronic systems. Implementation of shielding design tools requires adequate methods for evaluation of design layouts, guiding qualification testing, and an adequate follow-up on final design evaluation including results from a systems/device testing program tailored to meet design requirements.

  8. Radiation shielding effectiveness of newly developed superconductors (United States)

    Singh, Vishwanath P.; Medhat, M. E.; Badiger, N. M.; Saliqur Rahman, Abu Zayed Mohammad


    Gamma ray shielding effectiveness of superconductors with a high mass density has been investigated. We calculated the mass attenuation coefficients, the mean free path (mfp) and the exposure buildup factor (EBF). The gamma ray EBF was computed using the Geometric Progression (G-P) fitting method at energies 0.015-15 MeV, and for penetration depths up to 40 mfp. The fast-neutron shielding effectiveness has been characterized by the effective neutron removal cross-section of the superconductors. It is shown that CaPtSi3, CaIrSi3, and Bi2Sr2Ca1Cu2O8.2 are superior shielding materials for gamma rays and Tl0.6Rb0.4Fe1.67Se2 for fast neutrons. The present work should be useful in various applications of superconductors in fusion engineering and design.

  9. Electromagnetic shielding mats: facts and fiction. (United States)

    Leitgeb, N; Cech, R


    The use of electricity is accompanied by electric and magnetic fields which, intended or not, became a part of our environment. However, fear from environmental electromagnetic fields (EMFs) is widespread and so is business with fear. A number of more or less serious products including miracle products are placed on the market partly at excessive costs. By numerical simulation the efficiency of electromagnetic shielding mats was investigated and claims of manufacturers and their cited expert opinions checked. It could be shown that such products do not fulfil the justified expectations of customers, neither in the extremely low frequency (ELF) nor in the radiofrequency (RF) range. On the contrary, these mats usually make things even worse. The connection to ground, if available, might increase the belief on shielding efficiency, but in fact it even enhances fields instead of improving shielding. The electric conductivity of the mat material plays a minor role in the ELF range and enhances field increase in the RF range. It can not explain the enormous price differences. It could be shown that positive reports can be explained by result picking and exceptional arrangements of selected field sources. Overall, the investigation showed that manufacturer's claims about the shielding effectiveness are misleading and fool the customers about the real situation. Therefore, acquisition and use of electromagnetic shielding mats must be strongly discouraged.

  10. Using a mobile transparent plastic-lead-boron shielding barrier to reduce radiation dose exposure in the work place

    Energy Technology Data Exchange (ETDEWEB)

    Parra, S A; Mecozzi, J M


    Moveable radiation shielding barriers made of plastic material containing lead and boron can be used to reduce radiation exposure near the work place. Personnel can maneuver and position the transparent radiation shielding barriers anywhere within the work place. The lead in the shielding barrier provides an effective shielding material against radiation exposure (approximately a 1.0 mm lead equivalent protection) while the boron in the shielding barrier provides neutron absorption to reduce the moderation/reflection effects of the shielding materials (approximately a 2% {Delta}k/k reduction).

  11. Safety analysis and lay-out aspects of shieldings against particle radiation at the example of spallation facilities in the megawatt range; Sicherheitstechnische Analyse und Auslegungsaspekte von Abschirmungen gegen Teilchenstrahlung am Beispiel von Spallationsanlagen im Megawatt Bereich

    Energy Technology Data Exchange (ETDEWEB)

    Hanslik, R.


    This paper discusses the shielding of particle radiation from high current accelerators, spallation neutron sources and so called ADS-facilities (Accelerator Driven Systems). ADS-facilities are expected to gain importance in the future for transmutation of long-lived isotopes from fission reactors as well as for energy production. In this paper physical properties of the radiation as well as safety relevant requirements and corresponding shielding concepts are discussed. New concepts for the layout and design of such shielding are presented. Focal point of this work will be the fundamental difference between conventional fission reactor shielding and the safety relevant issues of shielding from high-energy radiation. Key point of this paper is the safety assessment of shielding issues of high current accelerators, spallation targets and ADS-blanket systems as well as neutron scattering instruments at spallation neutron sources. Safety relevant shielding requirements are presented and discussed. For the layout and design of the shielding for spallation sources computer base calculations methods are used. A discussion and comparison of the most important methods like semi-empirical, deterministic and stochastic codes are presented. Another key point within the presented paper is the discussion of shielding materials and their shielding efficiency concerning different types of radiation. The use of recycling material, as a cost efficient solution, is discussed. Based on the conducted analysis, flowcharts for a systematic layout and design of adequate shielding for targets and accelerators have been developed and are discussed in this paper. By use of these flowcharts layout and engineering design of future ADS-facilities can be performed. (orig.)

  12. Degradation of carbon-based materials under ablative conditions produced by a high enthalpy plasma jet

    Directory of Open Access Journals (Sweden)

    Gilberto Petraconi


    Full Text Available A stationary experiment was performed to study the degradation of carbon-based materials by immersion in a plasma jet. In the experiment, graphite and C/C composite were chosen as the target materials, and the reactive plasma jet was generated by an air plasma torch. For macroscopic study of the material degradation, the sample’s mass losses were measured as function of the exposure time under various temperatures on the sample surface. A microscopic analysis was then carried out for the study of microscopic aspects of the erosion of material surface. These experiments showed that the mass loss per unit area is approximately proportional to the exposure time and strongly depends on the temperature of the material surface. The mass erosion rate of graphite was appreciably higher than the C/C composite. The ablation rate in the carbon matrix region in C/C composite was also noticeably higher than that in the fiber region. In addition, the latter varied according to the orientation of fibers relatively to the flow direction. These tests indicated an excellent ablation resistance of the C/C composite, thus being a reliable material for rocket nozzles and heat shielding elements of the protection systems of hypersonic apparatuses from aerodynamic heating.

  13. Laser materials based on transition metal ions (United States)

    Moncorgé, Richard


    The purpose of this presentation is to review the spectroscopic properties of the main laser materials based on transition metal ions which lead to noticeable laser performance at room temperature and, for very few cases, because of unique properties, when they are operated at cryogenic temperatures. The description also includes the materials which are currently being used as saturable absorbers for passive-Q-switching of a variety of other near- and mid-infrared solid state lasers. A substantial part of the article is devoted first to the description of the energy levels and of the absorption and emission transitions of the transition metal ions in various types of environments by using the well-known Tanabe-Sugano diagrams. It is shown in particular how these diagrams can be used along with other theoretical considerations to understand and describe the spectroscopic properties of ions sitting in crystal field environments of near-octahedral or near-tetrahedral symmetry. The second part is then dedicated to the description (positions and intensities) of the main absorption and emission features which characterize the different types of materials.

  14. Research on ferromagnetic metal defects using pulsed eddy current testing based on aluminum shielding%基于铝屏蔽的铁磁性构件缺陷脉冲涡流检测研究

    Institute of Scientific and Technical Information of China (English)

    王蓉; 周德强


    针对铁磁性金属的缺陷检测,建立了铝屏蔽(真空磁屏蔽)与非屏蔽下的脉冲涡流检测有限元仿真模型,仿真分析了铁磁性材料下的电涡流与磁力线分布,并通过实验证实了仿真分析的有效性。仿真与实验结果表明:铝屏蔽下的脉冲涡流检测方法能有效的提高铁磁性材料的表面缺陷检测灵敏度,但对铁磁性金属内部缺陷检测效果不明显。%Aiming at the defects detection of ferromagnetic, the circle probes of the finite element models with aluminum shielding (vacuum magnetic shielding)and without shielding were built. Distribution of eddy current and magnetic field for two metal materials were simulated. The validity of simulation analysis was demonstrated by experimental results. The results show that the aluminum magnetic shielding of pulsed eddy current can improve effectively the sensitivity on surface defects of ferromagnetic metal. However, it is not obvious that it can not improve the sensitivity of internal defects of ferromagnetic metal defects.

  15. Spacecraft Electrostatic Radiation Shielding (United States)


    This project analyzed the feasibility of placing an electrostatic field around a spacecraft to provide a shield against radiation. The concept was originally proposed in the 1960s and tested on a spacecraft by the Soviet Union in the 1970s. Such tests and analyses showed that this concept is not only feasible but operational. The problem though is that most of this work was aimed at protection from 10- to 100-MeV radiation. We now appreciate that the real problem is 1- to 2-GeV radiation. So, the question is one of scaling, in both energy and size. Can electrostatic shielding be made to work at these high energy levels and can it protect an entire vehicle? After significant analysis and consideration, an electrostatic shield configuration was proposed. The selected architecture was a torus, charged to a high negative voltage, surrounding the vehicle, and a set of positively charged spheres. Van de Graaff generators were proposed as the mechanism to move charge from the vehicle to the torus to generate the fields necessary to protect the spacecraft. This design minimized complexity, residual charge, and structural forces and resolved several concerns raised during the internal critical review. But, it still is not clear if such a system is costeffective or feasible, even though several studies have indicated usefulness for radiation protection at energies lower than that of the galactic cosmic rays. Constructing such a system will require power supplies that can generate voltages 10 times that of the state of the art. Of more concern is the difficulty of maintaining the proper net charge on the entire structure and ensuring that its interaction with solar wind will not cause rapid discharge. Yet, if these concerns can be resolved, such a scheme may provide significant radiation shielding to future vehicles, without the excessive weight or complexity of other active shielding techniques.

  16. M-C simulation of shielding effects of PE, LiH and graphite fibers under 1 MeV electrons and 20 MeV protons

    Institute of Scientific and Technical Information of China (English)


    Shielding effects of different materials under 1 MeV electron and 20 MeV proton beams were simulated with Geant4 code. It was found that shielding effects of polyethylene and graphite fibers are much better than aluminum. Energy depositions in the phantom shielded by the materials are calculated, with the least energy deposition by graphite fiber shielding. The results show that graphite fibers are good radiation shielding material in space programs.

  17. GEANT4 and PHITS simulations of the shielding of neutrons from $^{252}$Cf source

    CERN Document Server

    Shin, Jae Won


    Neutron shielding simulations by using GEANT4 and PHITS code are performed. As a neutron source, $^{252}$Cf is considered and the energy distribution of the neutrons emitted from $^{252}$Cf is assumed the Watt fission spectrum. The neutron dose equivalent rates with and without the shield are estimated for shielding materials such as graphite, iron, polyethylene, NS-4-FR and KRAFTON-HB. For the neutron shielding simulations by using GEANT4, high precision (G4HP) model with G4NDL 4.2 based on ENDF-VII data are used. And for PHITS simulations, JENDL-4.0 library are used for the same purpose. It is found that differences between the shielding calculations by using GEANT4 with G4NDL 4.2 and PHITS with JENDL-4.0 library are not significant for all cases considered in this work. We investigate the accuracy of the neutron dose equivalent rates obtained from GEANT4 and PHITS by comparing our simulation results with experimental data and other values calculated earlier. Calculated neutron dose equivalent rates agree w...

  18. Wetting a rail tanker behind a noise shield. (United States)

    Rosmuller, Nils


    In the Netherlands, the Betuweline is a dedicated freight railway. It will, among other things, be used for transportation of all kinds of hazardous materials from the Port of Rotterdam to the German Hinterland and vice versa. The line is approximately 150 km long. Alongside the line, over more than 100 km noise shields are apparent. The question is to what extent this noise shield hinders the cooling of a rail tanker, carrying flammable liquid such as liquefied petroleum gas (LPG)? To answer this question, a full scale test was conducted on an already constructed part of the Betuweline [N. Rosmuller, D.W.G. Arentsen, (2005). Praktijkproeven Betuweroute: Instantane uitstroming en koeling 24 juni 2005, Nibra, Arnhem, The Netherlands]. Two railcars and a rail tanker were placed behind a 3m high noise shield. First, it was tested as to whether firemen or water canons should be used to deliver the water. Water canons were best next, four positions of the water canons to wet the rail tanker were tested. Three camera's and three observers recorded the locations and the extent of water that hit the rail tanker. The results indicate that the noise shield, to a large extent, prevents the water from hitting, and therefore cooling, the rail tanker. The upper parts of the rail tanker were minimally struck by the water canons and the small amount of water flowing down the rail tanker did not reach the lower parts of it because of the armatures at the rail tanker. Also, the amount of water in the ditches to be used for wetting was too small. The ditch nearby ran empty. These insights are both relevant to emergency responders for disaster abatement purposes and to water management organizations. The Ministry of Transport is examining the possible strategies to deal with these findings. The results are based upon one single full scale test near a 3m high noise shield. In addition, it would be valuable to determine what the influence would be of other heights of the noise shields.

  19. Nanocellulose-Based Materials for Water Purification

    Directory of Open Access Journals (Sweden)

    Hugo Voisin


    Full Text Available Nanocellulose is a renewable material that combines a high surface area with high strength, chemical inertness, and versatile surface chemistry. In this review, we will briefly describe how nanocellulose is produced, and present—in particular, how nanocellulose and its surface modified versions affects the adsorption behavior of important water pollutants, e.g., heavy metal species, dyes, microbes, and organic molecules. The processing of nanocellulose-based membranes and filters for water purification will be described in detail, and the uptake capacity, selectivity, and removal efficiency will also be discussed. The processing and performance of nanocellulose-based membranes, which combine a high removal efficiency with anti-fouling properties, will be highlighted.

  20. Negative Dielectric Constant Material Based on Ion Conducting Materials (United States)

    Gordon, Keith L. (Inventor); Kang, Jin Ho (Inventor); Park, Cheol (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)


    Metamaterials or artificial negative index materials (NIMs) have generated great attention due to their unique and exotic electromagnetic properties. One exemplary negative dielectric constant material, which is an essential key for creating the NIMs, was developed by doping ions into a polymer, a protonated poly(benzimidazole) (PBI). The doped PBI showed a negative dielectric constant at megahertz (MHz) frequencies due to its reduced plasma frequency and an induction effect. The magnitude of the negative dielectric constant and the resonance frequency were tunable by doping concentration. The highly doped PBI showed larger absolute magnitude of negative dielectric constant at just above its resonance frequency than the less doped PBI.

  1. Solution-based nanoengineering of materials.

    Energy Technology Data Exchange (ETDEWEB)

    Criscenti, Louise Jacqueline; Spoerke, Erik David; Liu, Jun; Voigt, James A.; Cygan, Randall Timothy; Machesky, Michael L. (Illinois State Water Survey, Champaign, IL); Tian, Zhengrong Ryan; McKenzie, Bonnie Beth


    Solution-based synthesis is a powerful approach for creating nano-structured materials. Although there have been significant recent successes in its application to fabricating nanomaterials, the general principles that control solution synthesis are not well understood. The purpose of this LDRD project was to develop the scientific principles required to design and build unique nanostructures in crystalline oxides and II/VI semiconductors using solution-based molecular self-assembly techniques. The ability to synthesize these materials in a range of different nano-architectures (from controlled morphology nanocrystals to surface templated 3-D structures) has provided the foundation for new opportunities in such areas as interactive interfaces for optics, electronics, and sensors. The homogeneous precipitation of ZnO in aqueous solution was used primarily as the model system for the project. We developed a low temperature, aqueous solution synthesis route for preparation of large arrays of oriented ZnO nanostructures. Through control of heterogeneous nucleation and growth, methods to predicatively alter the ZnO microstructures by tailoring the surface chemistry of the crystals were established. Molecular mechanics simulations, involving single point energy calculations and full geometry optimizations, were developed to assist in selecting appropriate chemical systems and understanding physical adsorption and ultimately growth mechanisms in the design of oxide nanoarrays. The versatility of peptide chemistry in controlling the formation of cadmium sulfide nanoparticles and zinc oxide/cadmium sulfide heterostructures was also demonstrated.

  2. A Review on the Production Methods and Testing of Textiles for Electro Magnetic Interference (EMI) shielding



    The need of the present generation to protect themselves from electromagnetic radiation due the various technological developments has paved way to the birth of EMI shielding of textiles. The shielding effectiveness of the developed fabric will vary depending upon the fabric or the coating constituents. The shielding requirements for different applications vary widely which has resulted in the development of wide variety of shielding mechanisms and materials which can be used in t...

  3. Characterization of a lead breast shielding for dose reduction in computed tomography*


    Correia,Paula Duarte; Granzotti, Cristiano Roberto Fabri; Santos, Yago da Silva; Brochi,Marco Aurelio Corte; Azevedo-Marques,Paulo Mazzoncini de


    Objective Several studies have been published regarding the use of bismuth shielding to protect the breast in computed tomography (CT) scans and, up to the writing of this article, only one publication about barium shielding was found. The present study was aimed at characterizing, for the first time, a lead breast shielding. Materials and Methods The percentage dose reduction and the influence of the shielding on quantitative imaging parameters were evaluated. Dose measurements were made on ...

  4. Shield-related signal instability in magnetoresistive heads (United States)

    Nakamoto, K.; Narumi, S.; Kawabe, T.; Kobayashi, T.; Fukui, H.


    Magnetoresistive (MR) heads with various upper shield materials were fabricated and their read-write performance was tested to clarify the shield-related effect on the signal instability in MR heads. Comparison of a head with an upper shield layer of higher magnetostriction and one with lower magnetostriction showed that the latter had better stability in the output signal of a repeated read-write test. The output amplitude of a head with an upper shield layer of Co52Ni27Fe21 film, which had a high magnetostriction of about +3×10-6, was varied by applying a low external longitudinal field, which affected just the shield layers. This change in the output corresponded well to the output variation in the repeated read-write test. The spin scanning electron micrograph image of this head revealed a distinct domain wall in the air bearing surface near the MR sensor. These results indicated that instability of the domain structure in a shield layer was one of the causes of the signal instability in MR heads; an unusual bias field from a domain wall of the shield layer, which could be moved easily by a repeated writing operation, caused a variation in the biased state of the MR layer which resulted in the signal variation, and that low magnetostriction was required for a shield material to achieve a stable head.

  5. Interfacial engineering of carbon nanofiber-graphene-carbon nanofiber heterojunctions in flexible lightweight electromagnetic shielding networks. (United States)

    Song, Wei-Li; Wang, Jia; Fan, Li-Zhen; Li, Yong; Wang, Chan-Yuan; Cao, Mao-Sheng


    Lightweight carbon materials of effective electromagnetic interference (EMI) shielding have attracted increasing interest because of rapid development of smart communication devices. To meet the requirement in portable electronic devices, flexible shielding materials with ultrathin characteristic have been pursued for this purpose. In this work, we demonstrated a facile strategy for scalable fabrication of flexible all-carbon networks, where the insulting polymeric frames and interfaces have been well eliminated. Microscopically, a novel carbon nanofiber-graphene nanosheet-carbon nanofiber (CNF-GN-CNF) heterojunction, which plays the dominant role as the interfacial modifier, has been observed in the as-fabricated networks. With the presence of CNF-GN-CNF heterojunctions, the all-carbon networks exhibit much increased electrical properties, resulting in the great enhancement of EMI shielding performance. The related mechanism for engineering the CNF interfaces based on the CNF-GN-CNF heterojunctions has been discussed. Implication of the results suggests that the lightweight all-carbon networks, whose thickness and density are much smaller than other graphene/polymer composites, present more promising potential as thin shielding materials in flexible portable electronics.

  6. Space Radiation and the Challenges Towards Effective Shielding Solutions (United States)

    Barghouty, Abdulnasser


    The hazards of space radiation and their effective mitigation strategies continue to pose special science and technology challenges to NASA. It is widely accepted now that shielding space vehicles and structures will have to rely on new and innovative materials since aluminum, like all high Z materials, are poor shields against the particulate and highly ionizing nature of space radiation. Shielding solutions, motivated and constrained by power and mass limitations, couple this realization with "multifunctionality," both in design concept as well as in material function and composition. Materials endowed with effective shielding properties as well as with some degree of multi-functionality may be the kernel of the so-called "radiation-smart" structures and designs. This talk will present some of the challenges and potential mitigation ideas towards the realization of such structures and designs.

  7. Gravity Scaling of a Power Reactor Water Shield (United States)

    Reid, Robert S.; Pearson, J. Boise


    Water based reactor shielding is being considered as an affordable option for use on initial lunar surface power systems. Heat dissipation in the shield from nuclear sources must be rejected by an auxiliary thermal hydraulic cooling system. The mechanism for transferring heat through the shield is natural convection between the core surface and an array of thermosyphon radiator elements. Natural convection in a 100 kWt lunar surface reactor shield design has been previously evaluated at lower power levels (Pearson, 2007). The current baseline assumes that 5.5 kW are dissipated in the water shield, the preponderance on the core surface, but with some volumetric heating in the naturally circulating water as well. This power is rejected by a radiator located above the shield with a surface temperature of 370 K. A similarity analysis on a water-based reactor shield is presented examining the effect of gravity on free convection between a radiation shield inner vessel and a radiation shield outer vessel boundaries. Two approaches established similarity: 1) direct scaling of Rayleigh number equates gravity-surface heat flux products, 2) temperature difference between the wall and thermal boundary layer held constant on Earth and the Moon. Nussult number for natural convection (laminar and turbulent) is assumed of form Nu = CRa(sup n). These combined results estimate similarity conditions under Earth and Lunar gravities. The influence of reduced gravity on the performance of thermosyphon heat pipes is also examined.

  8. Highly explosive nanosilicon-based composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Clement, D.; Diener, J.; Gross, E.; Kuenzner, N.; Kovalev, D. [Technical University of Munich, Physics Department, James-Franck-Str., 85747 Garching (Germany); Timoshenko, V.Yu. [Moscow State M.V. Lomonosov University, Physics Department, 119899 Moscow (Russian Federation)


    We present a highly explosive binary system based on porous silicon layers with their pores filled with solid oxidizers. The porous layers are produced by a standard electrochemical etching process and exhibit properties that are different from other energetic materials. Its production is completely compatible with the standard silicon technology and full bulk silicon wafers can be processed and therefore a large number of explosive elements can be produced simultaneously. The application-relevant parameters: the efficiency and the long-term stability of various porous silicon/oxidizer systems have been studied in details. Structural properties of porous silicon, its surface termination, the atomic ratio of silicon to oxygen and the chosen oxidizers were optimized to achieve the highest efficiency of the explosive reaction. This explosive system reveals various possible applications in different industrial fields, e.g. as a novel, very fast airbag igniter. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Starch-based completely biodegradable polymer materials

    Directory of Open Access Journals (Sweden)


    Full Text Available Starch is a natural polymer which possesses many unique properties and some shortcoming simultaneously. Some synthetic polymers are biodegradable and can be tailor-made easily. Therefore, by combining the individual advantages of starch and synthetic polymers, starch-based completely biodegradable polymers (SCBP are potential for applications in biomedical and environmental fields. Therefore it received great attention and was extensively investigated. In this paper, the structure and characteristics of starch and some synthetic degradable polymers are briefly introduced. Then, the recent progress about the preparation of SCBP via physical blending and chemical modification is reviewed and discussed. At last, some examples have been presented to elucidate that SCBP are promising materials for various applications and their development is a good solution for reducing the consumption of petroleum resources and environmental problem.

  10. Shielding of CO from dissociating radiation in interstellar clouds (United States)

    Glassgold, A. E.; Huggins, P. J.; Langer, W. D.


    The paper investigates the photodissociation of CO in interstellar clouds in the light of recent laboratory studies which suggest that line rather than continuum processes dominate its dissociation by ultraviolet radiation. Using a simple radiative transfer model, the shielding of representative dissociating bands is estimated, including self-shielding, mutual shielding between different isotopes, and near coincidences with strong lines of H2. Each of these processes materially affects the photodestruction rates of the various isotopic species in the transition regions of molecular clouds. These results are combined with an appropriate gas phase chemical model to determine how the abundances of the CO isotopes vary with depth into the cloud. It is found that self-shielding and mutual shielding cause significant variations in isotopic ratios. In addition, fractionation enhances species containing C-13. The relationship between the column densities of CO and H2 is found to vary for the different isotopes and to be sensitive to local conditions.

  11. Transparent Metal-Salt-Filled Polymeric Radiation Shields (United States)

    Edwards, David; Lennhoff, John; Harris, George


    "COR-RA" (colorless atomic oxygen resistant -- radiation shield) is the name of a transparent polymeric material filled with x-ray-absorbing salts of lead, bismuth, cesium, and thorium. COR-RA is suitable for use in shielding personnel against bremsstrahlung radiation from electron-beam welding and industrial and medical x-ray equipment. In comparison with lead-foil and leaded-glass shields that give equivalent protection against x-rays (see table), COR-RA shields are mechanically more durable. COR-RA absorbs not only x-rays but also neutrons and rays without adverse effects on optical or mechanical performance. The formulation of COR-RA with the most favorable mechanical-durability and optical properties contains 22 weight percent of bismuth to absorb x-rays, plus 45 atomic percent hydrogen for shielding against neutrons.

  12. Surface Functionalization of Graphene-based Materials (United States)

    Mathkar, Akshay

    Graphene-based materials have generated tremendous interest in the past decade. Manipulating their characteristics using wet-chemistry methods holds distinctive value, as it provides a means towards scaling up, while not being limited by yield. The majority of this thesis focuses on the surface functionalization of graphene oxide (GO), which has drawn tremendous attention as a tunable precursor due to its readily chemically manipulable surface and richly functionalized basal plane. Firstly, a room-temperature based method is presented to reduce GO stepwise, with each organic moiety being removed sequentially. Characterization confirms the carbonyl group to be reduced first, while the tertiary alcohol is reduced last, as the optical gap decrease from 3.5 eV down to 1 eV. This provides greater control over GO, which is an inhomogeneous system, and is the first study to elucidate the order of removal of each functional group. In addition to organically manipulating GO, this thesis also reports a chemical methodology to inorganically functionalize GO and tune its wetting characteristics. A chemical method to covalently attach fluorine atoms in the form of tertiary alkyl fluorides is reported, and confirmed by MAS 13C NMR, as two forms of fluorinated graphene oxide (FGO) with varying C/F and C/O ratios are synthesized. Introducing C-F bonds decreases the overall surface free energy, which drastically reduces GO's wetting behavior, especially in its highly fluorinated form. Ease of solution processing leads to development of sprayable inks that are deposited on a range of porous and nonporous surfaces to impart amphiphobicity. This is the first report that tunes the wetting characteristics of GO. Lastly as a part of a collaboration with ConocoPhillips, another class of carbon nanomaterials - carbon nanotubes (CNTs), have been inorganically functionalized to repel 30 wt% MEA, a critical solvent in CO 2 recovery. In addition to improving the solution processability of CNTs

  13. Shielding analysis and design of the KIPT experimental neutron source facility of Ukraine.

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Z.; Gohar, M. Y. A.; Naberezhnev, D.; Duo, J.; Nuclear Engineering Division


    Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of an experimental neutron source facility based on the use of an electron accelerator driven subcritical (ADS) facility [1]. The facility uses the existing electron accelerators of KIPT in Ukraine. The neutron source of the sub-critical assembly is generated from the interaction of 100 KW electron beam with a natural uranium target. The electron beam has a uniform spatial distribution and the electron energy in the range of 100 to 200 MeV, [2]. The main functions of the facility are the production of medical isotopes and the support of the Ukraine nuclear power industry. Reactor physics experiments and material performance characterization will also be carried out. The subcritical assembly is driven by neutrons generated by the electron beam interactions with the target material. A fraction of these neutrons has an energy above 50 MeV generated through the photo nuclear interactions. This neutron fraction is very small and it has an insignificant contribution to the subcritical assembly performance. However, these high energy neutrons are difficult to shield and they can be slowed down only through the inelastic scattering with heavy isotopes. Therefore the shielding design of this facility is more challenging relative to fission reactors. To attenuate these high energy neutrons, heavy metals (tungsten, iron, etc.) should be used. To reduce the construction cost, heavy concrete with 4.8 g/cm{sup 3} density is selected as a shielding material. The iron weight fraction in this concrete is about 0.6. The shape and thickness of the heavy concrete shield are defined to reduce the biological dose equivalent outside the shield to an acceptable level during operation. At the same time, special attention was give to reduce the total shield mass to reduce the construction cost. The shield design is configured

  14. Radiation Shielding Systems Using Nanotechnology (United States)

    Chen, Bin (Inventor); McKay, Christoper P. (Inventor)


    A system for shielding personnel and/or equipment from radiation particles. In one embodiment, a first substrate is connected to a first array or perpendicularly oriented metal-like fingers, and a second, electrically conducting substrate has an array of carbon nanostructure (CNS) fingers, coated with an electro-active polymer extending toward, but spaced apart from, the first substrate fingers. An electric current and electric charge discharge and dissipation system, connected to the second substrate, receives a current and/or voltage pulse initially generated when the first substrate receives incident radiation. In another embodiment, an array of CNSs is immersed in a first layer of hydrogen-rich polymers and in a second layer of metal-like material. In another embodiment, a one- or two-dimensional assembly of fibers containing CNSs embedded in a metal-like matrix serves as a radiation-protective fabric or body covering.

  15. Background simulations and shielding calculations (United States)

    Kudryavtsev, Vitaly A.


    Key improvements in the sensitivity of the underground particle astrophysics experiments can only be achieved if the radiation causing background events in detectors is well understood and proper measures are taken to suppress it. The background radiation arising from radioactivity and cosmic-ray muons is discussed here together with the methods of its suppression. Different shielding designs are considered to attenuate gamma-rays and neutrons coming from radioactivity in rock and lab walls. Purity of materials used in detector construction is analysed and the background event rates due to the presence of radioactive isotopes in detector components are discussed. Event rates in detectors caused by muon-induced neutrons with and without active veto systems are presented leading to the requirements for the depth of an underground laboratory and the efficiency of the veto system.

  16. FDI report on adverse reactions to resin-based materials. (United States)

    Fan, P L; Meyer, D M


    Resin-based restorative materials are considered safe for the vast majority of dental patients. Although constituent chemicals such as monomers, accelerators and initiators can potentially leach out of cured resin-based materials after placement, adverse reactions to these chemicals are rare and reaction symptoms commonly subside after removal of the materials. Dentists should be aware of the rare possibility that patients could have adverse reactions to constituents of resin-based materials and be vigilant in observing any adverse reactions after restoration placement. Dentists should also be cognisant of patient complaints about adverse reactions that may result from components of resin-based materials. To minimise monomer leaching and any potential risk of dermatological reactions, resin-based materials should be adequately cured. Dental health care workers should avoid direct skin contact with uncured resin-based materials. Latex and vinyl gloves do not provide adequate barrier protection to the monomers in resin-based materials.

  17. A contribution to shielding effectiveness analysis of shielded tents

    Directory of Open Access Journals (Sweden)

    Vranić Zoran M.


    Full Text Available An analysis of shielding effectiveness (SE of the shielded tents made of the metallised fabrics is given. First, two electromagnetic characteristic fundamental for coupling through electrically thin shield, the skin depth break frequency and the surface resistance or transfer impedance, is defined and analyzed. Then, the transfer function and the SE are analyzed regarding to the frequency range of interest to the Electromagnetic Compatibility (EMC Community.

  18. A Statistics-Based Material Property Analysis to Support TPS Characterization (United States)

    Copeland, Sean R.; Cozmuta, Ioana; Alonso, Juan J.


    Accurate characterization of entry capsule heat shield material properties is a critical component in modeling and simulating Thermal Protection System (TPS) response in a prescribed aerothermal environment. The thermal decomposition of the TPS material during the pyrolysis and charring processes is poorly characterized and typically results in large uncertainties in material properties as inputs for ablation models. These material property uncertainties contribute to large design margins on flight systems and cloud re- construction efforts for data collected during flight and ground testing, making revision to existing models for entry systems more challenging. The analysis presented in this work quantifies how material property uncertainties propagate through an ablation model and guides an experimental test regimen aimed at reducing these uncertainties and characterizing the dependencies between properties in the virgin and charred states for a Phenolic Impregnated Carbon Ablator (PICA) based TPS. A sensitivity analysis identifies how the high-fidelity model behaves in the expected flight environment, while a Monte Carlo based uncertainty propagation strategy is used to quantify the expected spread in the in-depth temperature response of the TPS. An examination of how perturbations to the input probability density functions affect output temperature statistics is accomplished using a Kriging response surface of the high-fidelity model. Simulations are based on capsule configuration and aerothermal environments expected during the Mars Science Laboratory (MSL) entry sequence. We identify and rank primary sources of uncertainty from material properties in a flight-relevant environment, show the dependence on spatial orientation and in-depth location on those uncertainty contributors, and quantify how sensitive the expected results are.

  19. Justification for Shielded Receiver Tube Additional Lead Shielding

    Energy Technology Data Exchange (ETDEWEB)

    BOGER, R.M.


    In order to reduce high radiation dose rates encountered when core sampling some radioactive waste tanks the addition of 240 lbs. of lead shielding is being considered to the shielded receiver tube on core sample trucks No.1, No.3 and No.4. The lead shielding is 4 inch diameter x 1/2 inch thick half rounds that have been installed around the SR tube over its' full length. Using three unreleased but independently reviewed structural analyses HNF-6018 justifies the addition of the lead shielding.

  20. Materials And Processes Technical Information System (MAPTIS) LDEF materials data base (United States)

    Funk, Joan G.; Strickland, John W.; Davis, John M.


    A preliminary Long Duration Exposure Facility (LDEF) Materials Data Base was developed by the LDEF Materials Special Investigation Group (MSIG). The LDEF Materials Data Base is envisioned to eventually contain the wide variety and vast quantity of materials data generated from LDEF. The data is searchable by optical, thermal, and mechanical properties, exposure parameters (such as atomic oxygen flux) and author(s) or principal investigator(s). Tne LDEF Materials Data Base was incorporated into the Materials and Processes Technical Information System (MAPTIS). MAPTIS is a collection of materials data which has been computerized and is available to engineers, designers, and researchers in the aerospace community involved in the design and development of spacecraft and related hardware. The LDEF Materials Data Base is described and step-by-step example searches using the data base are included. Information on how to become an authorized user of the system is included.

  1. Electrodynamic Dust Shield for Space Applications (United States)

    Mackey, Paul J.; Johansen, Michael R.; Olsen, Robert C.; Raines, Matthew G.; Phillips, James R., III; Cox, Rachel E.; Hogue, Michael D.; Pollard, Jacob R. S.; Calle, Carlos I.


    Dust mitigation technology has been highlighted by NASA and the International Space Exploration Coordination Group (ISECG) as a Global Exploration Roadmap (GER) critical technology need in order to reduce life cycle cost and risk, and increase the probability of mission success. The Electrostatics and Surface Physics Lab in Swamp Works at the Kennedy Space Center has developed an Electrodynamic Dust Shield (EDS) to remove dust from multiple surfaces, including glass shields and thermal radiators. Further development is underway to improve the operation and reliability of the EDS as well as to perform material and component testing outside of the International Space Station (ISS) on the Materials on International Space Station Experiment (MISSE). This experiment is designed to verify that the EDS can withstand the harsh environment of space and will look to closely replicate the solar environment experienced on the Moon.

  2. Polymers based on renewable raw materials

    Directory of Open Access Journals (Sweden)

    Jovanović Slobodan M.


    Full Text Available The basic raw materials for the chemical industry, which also means for polymer production, are mineral oil and natural gas. Mineral oil and natural gas resources are limited so that sooner or later they will be consumed. For this reason alternative, renewable raw materials for the chemical industry have become the object of intensive investigation all over the world. Some of the results of these investigations concerning renewable raw materials for the production of polymer materials are presented in this paper.

  3. Scaling mechanisms of vapour/plasma shielding from laser-produced plasmas to magnetic fusion regimes (United States)

    Sizyuk, Tatyana; Hassanein, Ahmed


    The plasma shielding effect is a well-known mechanism in laser-produced plasmas (LPPs) reducing laser photon transmission to the target and, as a result, significantly reducing target heating and erosion. The shielding effect is less pronounced at low laser intensities, when low evaporation rate together with vapour/plasma expansion processes prevent establishment of a dense plasma layer above the surface. Plasma shielding also loses its effectiveness at high laser intensities when the formed hot dense plasma plume causes extensive target erosion due to radiation fluxes back to the surface. The magnitude of emitted radiation fluxes from such a plasma is similar to or slightly higher than the laser photon flux in the low shielding regime. Thus, shielding efficiency in LPPs has a peak that depends on the laser beam parameters and the target material. A similar tendency is also expected in other plasma-operating devices such as tokamaks of magnetic fusion energy (MFE) reactors during transient plasma operation and disruptions on chamber walls when deposition of the high-energy transient plasma can cause severe erosion and damage to the plasma-facing and nearby components. A detailed analysis of these abnormal events and their consequences in future power reactors is limited in current tokamak reactors. Predictions for high-power future tokamaks are possible only through comprehensive, time-consuming and rigorous modelling. We developed scaling mechanisms, based on modelling of LPP devices with their typical temporal and spatial scales, to simulate tokamak abnormal operating regimes to study wall erosion, plasma shielding and radiation under MFE reactor conditions. We found an analogy in regimes and results of carbon and tungsten erosion of the divertor surface in ITER-like reactors with erosion due to laser irradiation. Such an approach will allow utilizing validated modelling combined with well-designed and well-diagnosed LPP experimental studies for predicting

  4. The axion shield

    CERN Document Server

    Andrianov, A A; Mescia, F; Renau, A


    We investigate the propagation of a charged particle in a spatially constant, but time dependent, pseudoscalar background. Physically this pseudoscalar background could be provided by a relic axion density. The background leads to an explicit breaking of Lorentz invariance; as a consequence the process p-> p gamma is possible and the background acts as a shield against extremely energetic cosmic rays, an effect somewhat similar to the GZK cut-off effect. The effect is model independent and can be computed exactly. The hypothetical detection of the photons radiated via this mechanism would provide an indirect way of verifying the cosmological relevance of axions.

  5. Process for making RF shielded cable connector assemblies and the products formed thereby (United States)

    Fisher, A.; Clatterbuck, C. H. (Inventor)


    A process for making RF shielded cable connector assemblies and the resulting structures is described. The process basically consists of potting wires of a shielded cable between the cable shield and a connector housing to fill in, support, regidize, and insulate the individual wires contained in the cable. The formed potting is coated with an electrically conductive material so as to form an entirely encompassing adhering conductive path between the cable shield and the metallic connector housing. A protective jacket is thereby formed over the conductive coating between the cable shield and the connector housing.

  6. Heavy Metal Pad Shielding during Fluoroscopic Interventions


    Dromi, Sergio; Wood, Bradford J.; Oberoi, Jay; Neeman, Ziv


    Significant direct and scatter radiation doses to patient and physician may result from routine interventional radiology practice. A lead-free disposable tungsten antimony shielding pad was tested in phantom patients during simulated diagnostic angiography procedures. Although the exact risk of low doses of ionizing radiation is unknown, dramatic dose reductions can be seen with routine use of this simple, sterile pad made from lightweighttungsten antimony material.

  7. Validity of the Aluminum Equivalent Approximation in Space Radiation Shielding (United States)

    Badavi, Francis F.; Adams, Daniel O.; Wilson, John W.


    The origin of the aluminum equivalent shield approximation in space radiation analysis can be traced back to its roots in the early years of the NASA space programs (Mercury, Gemini and Apollo) wherein the primary radiobiological concern was the intense sources of ionizing radiation causing short term effects which was thought to jeopardize the safety of the crew and hence the mission. Herein, it is shown that the aluminum equivalent shield approximation, although reasonably well suited for that time period and to the application for which it was developed, is of questionable usefulness to the radiobiological concerns of routine space operations of the 21 st century which will include long stays onboard the International Space Station (ISS) and perhaps the moon. This is especially true for a risk based protection system, as appears imminent for deep space exploration where the long-term effects of Galactic Cosmic Ray (GCR) exposure is of primary concern. The present analysis demonstrates that sufficiently large errors in the interior particle environment of a spacecraft result from the use of the aluminum equivalent approximation, and such approximations should be avoided in future astronaut risk estimates. In this study, the aluminum equivalent approximation is evaluated as a means for estimating the particle environment within a spacecraft structure induced by the GCR radiation field. For comparison, the two extremes of the GCR environment, the 1977 solar minimum and the 2001 solar maximum, are considered. These environments are coupled to the Langley Research Center (LaRC) deterministic ionized particle transport code High charge (Z) and Energy TRaNsport (HZETRN), which propagates the GCR spectra for elements with charges (Z) in the range I shield, and the effects of the aluminum equivalent approximation for a good polymeric shield material such as genetic polyethylene (PE). The shield thickness is represented by a 25 g/cm spherical shell. Although one could

  8. X射线异物检测的图像屏蔽算法%The Application of Image Shielding Method in the X-ray Foreign Material Detection

    Institute of Scientific and Technical Information of China (English)

    项安; 张晗毓


    In the X-ray foreign material detection process, it is often misjudged some parts of the packaged products as foreign bodies, because the X-ray absorption in these parts are similar to that in the foreign bodies. However, the problem can be well solved by using image mask methods. To this problem, this paper put forward four kinds of image mask methods by combining the basic theories of image segmentation and the detection principle of X-ray foreign material inspection system. Matlab simulation results show that those error detection parts can be masked effectively by using corresponding mask method. And to some extent, it is proved that the proposed mask methods improve the sensitivity of the X-ray foreign material detection system and have good commercial use value.%X射线异物检测系统检测包装食品过程中,由于产品某些包装区域的材质以及厚度特征,此区域对X射线的吸收率与异物对X射线的吸收率十分相似,导致系统在异物识别时将这些区域误判为异物,造成误检.针对此类问题,结合X射线异物检测原理和图像分割理论,提出了4种图像屏蔽方法.Matlab仿真结果表明,针对不同检测产品采用相应的屏蔽算法,均可有效屏蔽该检测产品中被误判为异物的区域,大大提高了X射线异物检测系统的灵敏度,具有较好的商业使用价值.

  9. The preliminary Long Duration Exposure Facility (LDEF) materials data base (United States)

    Funk, Joan G.; Strickland, John W.; Davis, John M.


    A preliminary Long Duration Exposure Facility (LDEF) Materials Data Base was developed by the LDEF Materials Special Investigation Group (MSIG). The LDEF Materials Data Base is envisioned to eventually contain the wide variety and vast quantity of materials data generated for LDEF. The data is searchable by optical, thermal, and mechanical properties, exposure parameters (such as atomic oxygen flux), and author(s) or principal investigator(s). The LDEF Materials Data Base was incorporated into the Materials and Processes Technical Information System (MAPTIS). MAPTIS is a collection of materials data which was computerized and is available to engineers, designers, and researchers in the aerospace community involved in the design and development of spacecraft and related hardware. This paper describes the LDEF Materials Data Base and includes step-by-step example searches using the data base. Information on how to become an authorized user of the system is included.

  10. Optimization of the National Ignition Facility primary shield design

    Energy Technology Data Exchange (ETDEWEB)

    Annese, C.E.; Watkins, E.F.; Greenspan, E.; Miller, W.F. [California Univ., Berkeley, CA (United States). Dept. of Nuclear Engineering; Latkowski, J.; Lee, J.D.; Soran, P.; Tobin, M.L. [Lawrence Livermore National Lab., CA (United States)


    Minimum cost design concepts of the primary shield for the National Ignition laser fusion experimental Facility (NIF) are searched with the help of the optimization code SWAN. The computational method developed for this search involves incorporating the time dependence of the delayed photon field within effective delayed photon production cross sections. This method enables one to address the time-dependent problem using relatively simple, time-independent transport calculations, thus significantly simplifying the design process. A novel approach was used for the identification of the optimal combination of constituents that will minimize the shield cost; it involves the generation, with SWAN, of effectiveness functions for replacing materials on an equal cost basis. The minimum cost shield design concept was found to consist of a mixture of polyethylene and low cost, low activation materials such as SiC, with boron added near the shield boundaries.

  11. Smart material-based radiation sources (United States)

    Kovaleski, Scott


    From sensors to power harvesters, the unique properties of smart materials have been exploited in numerous ways to enable new applications and reduce the size of many useful devices. Smart materials are defined as materials whose properties can be changed in a controlled and often reversible fashion by use of external stimuli, such as electric and magnetic fields, temperature, or humidity. Smart materials have been used to make acceleration sensors that are ubiquitous in mobile phones, to make highly accurate frequency standards, to make unprecedentedly small actuators and motors, to seal and reduce friction of rotating shafts, and to generate power by conversion of either kinetic or thermal energy to electrical energy. The number of useful devices enabled by smart materials is large and continues to grow. Smart materials can also be used to generate plasmas and accelerate particles at small scales. The materials discussed in this talk are from non-centrosymmetric crystalline classes including piezoelectric, pyroelectric, and ferroelectric materials, which produce large electric fields in response to external stimuli such as applied electric fields or thermal energy. First, the use of ferroelectric, pyroelectric and piezoelectric materials for plasma generation and particle acceleration will be reviewed. The talk will then focus on the use of piezoelectric materials at the University of Missouri to construct plasma sources and electrostatic accelerators for applications including space propulsion, x-ray imaging, and neutron production. The basic concepts of piezoelectric transformers, which are analogous to conventional magnetic transformers, will be discussed, along with results from experiments over the last decade to produce micro-thrusters for space propulsion and particle accelerators for x-ray and neutron production. Support from ONR, AFOSR, and LANL.

  12. Coping with Water Gushing in Shield Arrival%盾构到达突发涌水处理及水中到达方案分析

    Institute of Scientific and Technical Information of China (English)



    Water gushing,sand inrush and collapse are prone to occur in shield arrival,which is one of the major risks in shield tunneling.Water gushing occurs in the shield arrival in a tunneling project.In order to cope with the gushing water,a shield receiving chamber made of reinforced concrete is built.The shield receiving method mentioned is mainly based on the idea of keeping balance in shield arriving.The shield receiving chamber made of reinforced concrete is closely connected to the tunnel portal and is filled with filling materials to keep the pressure in the chamber equal to the original soil pressure so as to simulate the shield tunneling conditions in the original soil and to ensure the safety during shield arrival.%盾构到达时易出现涌水、涌砂、上覆土体坍塌等事故,是盾构施工的重大风险点之一.通过盾构到达突发涌水事故解决实例,介绍事故发生后采用钢筋昆凝土接收洞室进行盾构水中到达的施工经验.钢筋混凝土接收洞室基于平衡到达理念,采用密闭的箱型混凝土结构与隧道洞门密闭连接,并在箱体内灌入填充物,以达到与土层压力平衡,模拟盾构在土体中的掘进状态,使盾构安全进入接收洞室内.

  13. Friction and wear in polymer-based materials

    CERN Document Server

    Bely, V A; Petrokovets, M I


    Friction and Wear in Polymer-Based Materials discusses friction and wear problems in polymer-based materials. The book is organized into three parts. The chapters in Part I cover the basic laws of friction and wear in polymer-based materials. Topics covered include frictional interaction during metal-polymer contact and the influence of operating conditions on wear in polymers. The chapters in Part II discuss the structure and frictional properties of polymer-based materials; the mechanism of frictional transfer when a polymer comes into contact with polymers, metals, and other materials; and

  14. New Toroid shielding design

    CERN Multimedia

    Hedberg V

    On the 15th of June 2001 the EB approved a new conceptual design for the toroid shield. In the old design, shown in the left part of the figure above, the moderator part of the shielding (JTV) was situated both in the warm and cold areas of the forward toroid. It consisted both of rings of polyethylene and hundreds of blocks of polyethylene (or an epoxy resin) inside the toroid vacuum vessel. In the new design, shown to the right in the figure above, only the rings remain inside the toroid. To compensate for the loss of moderator in the toroid, the copper plug (JTT) has been reduced in radius so that a layer of borated polyethylene can be placed around it (see figure below). The new design gives significant cost-savings and is easier to produce in the tight time schedule of the forward toroid. Since the amount of copper is reduced the weight that has to be carried by the toroid is also reduced. Outgassing into the toroid vacuum was a potential problem in the old design and this is now avoided. The main ...

  15. Nanostructured conductive polymeric materials (United States)

    Al-Saleh, Mohammed H.

    Conductive polymer composites (CPCs) are a suitable alternative to metals in many applications due to their light-weight, corrosion resistance, low cost, ease of processing and design flexibility. CPCs have been formulated using different types of conductive fillers. In this PhD thesis, the focus is on CPCs for electrostatic discharge (ESD) protection and electromagnetic interference (EMI) attenuation. Despite the versatility of conductive fillers, carbon black (CB) has been the dominant filler to make CPCs for ESD protection applications because CB/polymer composites have a cost advantage over all other CPCs. For EMI shielding, stainless steel fibres and metal coated fibers are the preferred fillers, however CPCs made of those fibers are not the dominant EMI shielding materials. Metal coated and polymer plated polymers are the most widely used EMI shielding options. The limited use of CPCs in the EMI shielding market is because the high filler loading required to formulate a composite with an adequate level of shielding remarkably increases the composite price. In order to increase the competitiveness of CPCs, percolation threshold should be minimized as much as possible and composites with high EMI shielding capabilities at low filler loading should be formulated because all conductive fillers are expensive compared to polymers. In this thesis, two different methodologies to reduce percolation threshold in CPCs have been successfully developed and a CPC with exceptional EMI shielding capability has been formulated using copper nanowires as conductive filler. The first percolation threshold reduction technique is based on the selective localization of CB at the interface of immiscible polymer blend. The technique requires adding a copolymer that prefers the blend's interface and for which CB nanoparticles has the highest affinity. The second method is based on producing a CPC powder and then using this powder as a conductive filler to produce composite by dry

  16. Analysis methods for Kevlar shield response to rotor fragments (United States)

    Gerstle, J. H.


    Several empirical and analytical approaches to rotor burst shield sizing are compared and principal differences in metal and fabric dynamic behavior are discussed. The application of transient structural response computer programs to predict Kevlar containment limits is described. For preliminary shield sizing, present analytical methods are useful if insufficient test data for empirical modeling are available. To provide other information useful for engineering design, analytical methods require further developments in material characterization, failure criteria, loads definition, and post-impact fragment trajectory prediction.

  17. The effect of breast shielding during lumbar spine radiography:


    Žontar, Dejan; Škrk, Damijan; Mekiš, Nejc


    Background The aim of the study was to determine the influence of lead shielding on the dose to female breasts in conventional x-ray lumbar spine imaging. The correlation between the body mass index and the dose received by the breast was also investigated. Materials and methods Breast surface dose was measured by thermoluminescent dosimeters (TLD). In the first phase measurements of breast dose with and without shielding from lumbar spine imaging in two projections were conducted on an anthr...

  18. Drip Shield Emplacement Gantry Concept

    Energy Technology Data Exchange (ETDEWEB)

    Silva, R.A.; Cron, J.


    This design analysis has shown that, on a conceptual level, the emplacement of drip shields is feasible with current technology and equipment. A plan for drip shield emplacement was presented using a Drip Shield Transporter, a Drip Shield Emplacement Gantry, a locomotive, and a Drip Shield Gantry Carrier. The use of a Drip Shield Emplacement Gantry as an emplacement concept results in a system that is simple, reliable, and interfaces with the numerous other exising repository systems. Using the Waste Emplacement/Retrieval System design as a basis for the drip shield emplacement concept proved to simplify the system by using existing equipment, such as the gantry carrier, locomotive, Electrical and Control systems, and many other systems, structures, and components. Restricted working envelopes for the Drip Shield Emplacement System require further consideration and must be addressed to show that the emplacement operations can be performed as the repository design evolves. Section 6.1 describes how the Drip Shield Emplacement System may use existing equipment. Depending on the length of time between the conclusion of waste emplacement and the commencement of drip shield emplacement, this equipment could include the locomotives, the gantry carrier, and the electrical, control, and rail systems. If the exisiting equipment is selected for use in the Drip Shield Emplacement System, then the length of time after the final stages of waste emplacement and start of drip shield emplacement may pose a concern for the life cycle of the system (e.g., reliability, maintainability, availability, etc.). Further investigation should be performed to consider the use of existing equipment for drip shield emplacement operations. Further investigation will also be needed regarding the interfaces and heat transfer and thermal effects aspects. The conceptual design also requires further design development. Although the findings of this analysis are accurate for the assumptions made

  19. Biodegradable starch-based polymeric materials (United States)

    Suvorova, Anna I.; Tyukova, Irina S.; Trufanova, Elena I.


    The effects of low-molecular-weight additives, temperature and mechanical action on the structure and properties of starch are discussed. Special attention is given to mixtures of starch with synthetic polymers, e.g., co-polymers of ethylene with vinyl acetate, vinyl alcohol, acrylic acid, cellulose derivatives and other natural polymers. These mixtures can be used in the development of novel environmentally safe materials (films, coatings, packaging materials) and various articles for short-term use. The bibliography includes 105 references.

  20. Optical Limiting Materials Based on Gold Nanoparticles (United States)


    Murphy, University of Illinois at Urbana-Champaign (formerly University of South Carolina), Department of Chemistry Award Number: FA9550-09-1-0246...of the electromagnetic spectrum. 2. Functionalization of the surface of the gold nanoparticles with selected organic and inorganic materials, with...the thesis work of one Ph.D. student (Sean Sivapalan, Ph.D. in materials science and engineering, graduated in 2013, now employed at Intel

  1. 基于随机理论的特高压输电线路雷电屏蔽模型%Modeling of Lightning Shielding Failure in UHV Transmission Line Based on Randomness Theory

    Institute of Scientific and Technical Information of China (English)

    伏进; 杨庆; 司马文霞


    The operation data obtained abroad indicates that shielding failure in UHV transmission lines mostly accounts for the tripping-out accidents introduced by lightning striking the transmission line. Based on the discharge theories of long air gap and randomness theory, a leader progression model of lightning shielding failure is presented in this paper. The random characteristics of the downward and upward leader are simulated in this model. The ground slope angel is also considered in this model by using coordinate transformation. Moreover, the system voltage is also taken into consideration in this model. The simulation results show that the good agreement between this model and the field data. And the results suggest that return striking exist obviously in UHV transmission line.

  2. 核用碳化硼制备工艺研究进展%Progress in preparation of boron carbides used as nuclear shielding material

    Institute of Scientific and Technical Information of China (English)

    郑伟; 徐姣; 张卫江


    Boron carbides are very important materials in refractory liners, dies, bearings, sandblasting nozzles and nuclear industry. In this paper, the production processes for boron carbides are introduced, which include the carbothermal reduction, self-propagation high-temperature synthesis, chemical vapor deposition and sol-gel carbothermal reduction method. The advantages and disadvantages of all the methods are compared. The difficulties, problems and development direction of how to produce boron carbides are discussed.%碳化硼是一种被广泛应用在耐火材料、模具、轴承、喷嘴和核工业中的新型材料,主要介绍了有关制备碳化硼的工艺,其主要包括碳热还原法、自蔓延热还原法、化学气相沉积法和溶胶-凝胶碳热还原法.通过对比指出各种方法的优缺点,探讨了碳化硼制备的研究现状、存在的问题及发展方向.

  3. Test method for shielding effects of clothing fabrics by shield box method%服装用织物屏蔽效能测试方法—屏蔽箱法的探讨

    Institute of Scientific and Technical Information of China (English)

    刘志才; 何鹏; 徐勤; 王利君; 李妮; 熊杰


    基于电磁波的屏蔽原理,采用一种新的测试织物电磁屏蔽效能的方法-屏蔽箱法,对增重率不同的化学镀银聚酰胺6织物进行测试.结果表明:发射源与人的距离可以用发射源与屏蔽材料的距离来模拟;织物屏蔽效能随着镀层增重率的增加而提高,提高到一定程度后屏蔽效能值趋于稳定;材料性能的变化可以用屏蔽箱法测试的数据直接反映;这种测试织物屏蔽效能的方法经济有效,且测试结果具有较好的重复性.%Based on the theory of shielding against electromagnetic radiation,a new device by shield box was designed to test electromagnetic shielding effects of polyamide 6 (PA6) fabrics that had been treated by electroless plating with silver by varying the weighting percentage.The results indicated that the distance between the radiation source and person could be simulated by the distance between the radiation source and the shielding material.The fabric shielding effects increased with the increase of the weighting percentage,but when to a certain extent they tended to be stable,which meant that the test data obtained from the shield box can directly reflect the change of fabric performance.This shield box method is costeffective and has good reproducibility.

  4. Magnesium Based Materials and their Antimicrobial Activity (United States)

    Robinson, Duane Allan

    that nMgO has similar effects. Incorporation of nMgO into a PCL composite was easily achieved and revealed similar, although not identical antimicrobial results. This work has provided a strong foundation and methodology for further evaluation of Mg based materials and their antimicrobial properties.

  5. New Materials for Chalcogenide Based Solar Cells (United States)

    Tosun, Banu Selin

    Thin film solar cells based on copper indium gallium diselenide (CIGS) have achieved efficiencies exceeding 20 %. The p-n junction in these solar cells is formed between a p-type CIGS absorber layer and a composite n-type film that consists of a 50-100 nm thin n-type CdS followed by a 50-200 nm thin n-type ZnO. This dissertation focuses on developing materials for replacing CdS and ZnO films to improve the damp-heat stability of the solar cells and for minimizing the use of Cd. Specifically, I demonstrate a new CIGS solar cell with better damp heat stability wherein the ZnO layer is replaced with SnO2. The efficiency of solar cells made with SnO2 decreased less than 5 % after 120 hours at 85 °C and 85 % relative humidity while the efficiency of solar cells made with ZnO declined by more than 70 %. Moreover, I showed that a SnO2 film deposited on top of completed CIGS solar cells significantly increased the device lifetime by forming a barrier against water diffusion. Semicrystalline SnO2 films deposited at room temperature had nanocrystals embedded in an amorphous matrix, which resulted in films without grain boundaries. These films exhibited better damp-heat stability than ZnO and crystalline SnO2 films deposited at higher temperature and this difference is attributed to the lack of grain boundary water diffusion. In addition, I studied CBD of Zn1-xCdxS from aqueous solutions of thiourea, ethylenediaminetetraacetic acid and zinc and cadmium sulfate. I demonstrated that films with varying composition (x) can be deposited through CBD and studied the structure and composition variation along the films' thickness. However, this traditional chemical bath deposition (CBD) approach heats the entire solution and wastes most of the chemicals by homogenous particle formation. To overcome this problem, I designed and developed a continuous-flow CBD approach to utilize the chemicals efficiently and to eliminate homogenous particle formation. Only the substrate is heated to

  6. Physical analysis of the shielding capacity for a lightweight apron designed for shielding low intensity scattering X-rays


    Seon Chil Kim; Jeong Ryeol Choi; Byeong Kyou Jeon


    The purpose of this paper is to develop a lightweight apron that will be used for shielding low intensity radiation in medical imaging radiography room and to apply it to a custom-made effective shielding. The quality of existing aprons made for protecting our bodies from direct radiation are improved so that they are suitable for scattered X-rays. Textiles that prevent bodies from radiation are made by combining barium sulfate and liquid silicon. These materials have the function of shieldin...

  7. Constraints on target chamber first wall and target designs that will enable NIF debris shields to survive (United States)

    Burnham, Alan K.; Gerassimenko, Michel; Scott, J. M.; Latkowski, Jeff F.; Whitman, Pamela K.; Genin, Francois Y.; Hibbard, Wilthea; Peterson, P. F.; Tokheim, R. E.; Curran, D. R.


    The NIF target chamber interior materials and target designs themselves have to be compatible with survival of the final- optics debris shields. To meet the planned maintenance and refinishing rate, the contamination of the debris shields cannot exceed about 1 nm equivalent thickness per shot of total material. This implies that he target mass must be limited to no more than 1 gram and the ablated mass released to the chamber from all other components must not exceed 3 grams. In addition, the targets themselves must either completely vaporize or send any minor amounts of shrapnel towards the chamber waist to prevent excessive catering of the debris shields. The constraints on the first-wall debris will remobilize at a rate fast enough to require cleaning every 3 weeks, about three times more frequent than possible with planned robotics. Furthermore, a comparison of ablatants from B4C and stainless-steel louvers suggest that remobilization of target debris by x-rays will be greater than that of the base material in both cases, thereby reducing the performance advantage of clean B4C over much cheaper stainless steel. Neutronics calculations indicate that activation of thin Ni-free stainless steel is not a significant source of maintenance personnel radiation dose. Consequently, the most attractive first wall design consists of stainless-steel louvers. Evaluation of various unconverted-light beam dump designs indicates that stainless steel louvers generate no more debris than other matrices, so one single design can serve as both first wall and beam dumps, eliminating beam steering restrictions caused by size and location of the beam dumps. One reservation is that the allowable contamination rate of the debris shield is not yet completely understood. Consequently, it is likely that either a protruding beam tube, a rapid post-shot gas purge of the final optics assembly, or thin polymeric pre-shield will be required to prevent low-velocity contamination from reaching

  8. The assembly of the disk shielding is finished.

    CERN Multimedia

    Vincent Hedberg

    At the end of March, the shielding project engineer, Jan Palla, could draw a sigh of relief when the fourth and final rotation of the disk shielding was carried out without incident. The two 80-ton heavy shielding assemblies were built in a horizontal position and they had to be first turned upside-down and then rotated to a vertical position during the assembly. The relatively thin disk plate with a diameter of 9 meters, made this operation quite delicate and a lot of calculation work and strengthening of the shielding was carried out before the rotations could take place. The disk shielding is being turned upside-down. The stainless steel cylinder in the centre supports the shielding as well as the small muon wheel. The two disk shielding assemblies consist of different materials such as bronze, gray steel, cast iron, stainless steel, boron doped polyethylene and lead. The project is multinational with the major pieces having been made by companies in Armenia, Serbia, Spain, Bulgaria, Italy, Slovaki...

  9. Thick Galactic Cosmic Radiation Shielding Using Atmospheric Data (United States)

    Youngquist, Robert C.; Nurge, Mark A.; Starr, Stanley O.; Koontz, Steven L.


    NASA is concerned with protecting astronauts from the effects of galactic cosmic radiation and has expended substantial effort in the development of computer models to predict the shielding obtained from various materials. However, these models were only developed for shields up to about 120 g!cm2 in thickness and have predicted that shields of this thickness are insufficient to provide adequate protection for extended deep space flights. Consequently, effort is underway to extend the range of these models to thicker shields and experimental data is required to help confirm the resulting code. In this paper empirically obtained effective dose measurements from aircraft flights in the atmosphere are used to obtain the radiation shielding function of the earth's atmosphere, a very thick shield. Obtaining this result required solving an inverse problem and the method for solving it is presented. The results are shown to be in agreement with current code in the ranges where they overlap. These results are then checked and used to predict the radiation dosage under thick shields such as planetary regolith and the atmosphere of Venus.

  10. Welding shield for coupling heaters (United States)

    Menotti, James Louis


    Systems for coupling end portions of two elongated heater portions and methods of using such systems to treat a subsurface formation are described herein. A system may include a holding system configured to hold end portions of the two elongated heater portions so that the end portions are abutted together or located near each other; a shield for enclosing the end portions, and one or more inert gas inlets configured to provide at least one inert gas to flush the system with inert gas during welding of the end portions. The shield may be configured to inhibit oxidation during welding that joins the end portions together. The shield may include a hinged door that, when closed, is configured to at least partially isolate the interior of the shield from the atmosphere. The hinged door, when open, is configured to allow access to the interior of the shield.

  11. Luminescent hybrid materials based on laponite clay. (United States)

    Li, Huanrong; Li, Man; Wang, Yu; Zhang, Wenjun


    The spectroscopic behavior of ionic Eu(3+) or Tb(3+) complexes of an aromatic carboxyl-functionalized organic salt as well as those of the hybrid materials derived from adsorption of the ionic complexes on Laponite clay are reported. X-ray diffraction (XRD) patterns suggest that the complexes are mainly adsorbed on the outer surfaces of the Laponite disks rather than intercalated within the interlayer spaces. Photophysical data showed that the energy-transfer efficiency from the ligand to Eu(3+) ions in the hybrid material is increased remarkably with respect to the corresponding ionic complex. The hybrid material containing the Eu(3+) complex shows bright red emission from the prominent (5) D0 →(7) F2 transition of Eu(3+) ions, and that containing the Tb(3+) complex exhibits bright green emission due to the dominant (5) D4 →(7) F5 transition of Tb(3+) ions.

  12. Stretchable, curvilinear electronics based on inorganic materials. (United States)

    Kim, Dae-Hyeong; Xiao, Jianliang; Song, Jizhou; Huang, Yonggang; Rogers, John A


    All commercial forms of electronic/optoelectronic technologies use planar, rigid substrates. Device possibilities that exploit bio-inspired designs or require intimate integration with the human body demand curvilinear shapes and/or elastic responses to large strain deformations. This article reviews progress in research designed to accomplish these outcomes with established, high-performance inorganic electronic materials and modest modifications to conventional, planar processing techniques. We outline the most well developed strategies and illustrate their use in demonstrator devices that exploit unique combinations of shape, mechanical properties and electronic performance. We conclude with an outlook on the challenges and opportunities for this emerging area of materials science and engineering.

  13. Nanostructured composite layers for electromagnetic shielding in the GHz frequency range

    Energy Technology Data Exchange (ETDEWEB)

    Suchea, M. [Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Chemistry and Physics, “Al.I. Cuza” University of Iasi, Iasi (Romania); Tudose, I.V. [Chemistry and Physics, “Al.I. Cuza” University of Iasi, Iasi (Romania); Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Tzagkarakis, G. [Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Electrical Engineering Department, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Kenanakis, G. [Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Institute of Electronic Structure & Laser (IESL), Foundation for Research and Technology (FORTH) Hellas, Heraklion (Greece); Katharakis, M. [Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Drakakis, E. [Electrical Engineering Department, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Koudoumas, E., E-mail: [Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Electrical Engineering Department, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece)


    Graphical abstract: - Highlights: • Paint-like nanocomposite layers consisting of graphene nanoplatelets, PANI:HCl and PEDOT:PSS present very effective attenuation of electromagnetic radiation in the frequency range 4–20 GHz. • The shielding performance is based mostly on the graphene nanoplatelets and supported by PANI:HCl. In contrast, PEDOT:PSS plays mainly the role of the binder. • Increasing resistivity was observed to reduce the shielding effect, while increasing thickness to favor it. - Abstract: We report on preliminary results regarding the applicability of nanostructured composite layers for electromagnetic shielding in the frequency range of 4–20 GHz. Various combinations of materials were employed including poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), polyaniline, graphene nanoplatelets, carbon nanotubes, Cu nanoparticles and Poly(vinyl alcohol). As shown, paint-like nanocomposite layers consisting of graphene nanoplatelets, polyaniline PEDOT:PSS and Poly(vinyl alcohol) can offer quite effective electromagnetic shielding, similar or even better than that of commercial products, the response strongly depending on their thickness and resistivity.

  14. Preparation and characterisation of Isophthalic-Bi2O3 polymer composite gamma radiation shields (United States)

    Ambika, M. R.; Nagaiah, N.; Harish, V.; Lokanath, N. K.; Sridhar, M. A.; Renukappa, N. M.; Suman, S. K.


    Bi2O3 filled Isophthalic resin based polymer composites of different weight % (0, 5, 10, 20, 30, 40, 50 & 60) were fabricated by open mould cast technique. Gamma attenuation study was carried out using NaI (Tl) gamma ray spectrometer for Cs-137. The shielding parameters such as attenuation coefficient, HVL & λ were investigated. The distribution of the filler within the matrix was studied using Scanning Electron Microscopy. X ray diffractometer and Fourier Transform Infrared Spectroscopy were employed to study the structural changes if any. The thermal stability and mechanical strength of the composites were investigated using TGA & UTM respectively. Dielectric properties and AC conductivity were also studied using LCR meter. The composites are found to be thermally stable upto 200 °C. There were no such structural changes observed and all the composites show very low conductivity. The mechanical strength of the composites was found to increase upon adding the bismuth oxide with a slight decrease when the concentration of the filler exceeds 40 wt%. Attenuation results reveal that, the shielding efficiency increases with the increase of the filler wt% and are comparable to those of the conventional shielding materials. Hence, Bi2O3 filled composites can be used for gamma shielding applications.

  15. Analysis for Radiation and Shielding Dose in Plasma Focus Neutron Source Using FLUKA (United States)

    Nemati, M. J.; Amrollahi, R.; Habibi, M.


    Monte Carlo simulations have been performed for the attenuation of neutron radiation produced at Plasma focus (PF) devices through various shielding design. At the test site it will be fired with deuterium and tritium (D-T) fusion resulting in a yield of about 1013 fusion neutrons of 14 MeV. This poses a radiological hazard to scientists and personnel operating the device. The goal of this paper was to evaluate various shielding options under consideration for the PF operating with D-T fusion. Shields of varying neutrons-shielding effectiveness were investigated using concrete, polyethylene, paraffin and borated materials. The most effective shield, a labyrinth structure, allowed almost 1,176 shots per year while keeping personnel under 20 mSV of dose. The most expensive shield that used, square shield with 100 cm concrete thickness on the walls and Borated paraffin along with borated polyethylene added outside the concrete allowed almost 15,000 shot per year.


    Energy Technology Data Exchange (ETDEWEB)

    Mattus, Catherine H.; Dole, Leslie R.


    The depleted uranium (DU) inventory in the United States exceeds 500,000 metric tonnes. To evaluate the possibilities for reuse of this stockpile of DU, the U.S. Department of Energy (DOE) has created a research and development program to address the disposition of its DU(1). One potential use for this stockpile material is in the fabrication of nuclear shielding casks for the storage, transport, and disposal of spent nuclear fuels. The use of the DU-based shielding would reduce the size and weight of the casks while allowing a level of protection from neutrons and gamma rays comparable to that afforded by steel and concrete. DUAGG (depleted uranium aggregate) is formed of depleted uranium dioxide (DUO2) sintered with a synthetic-basalt-based binder. This study was designed to investigate possible deleterious reactions that could occur between the cement paste and the DUAGG. After 13 months of exposure to a cement pore solution, no deleterious expansive mineral phases were observed to form either with the DUO2 or with the simulated-basalt sintering phases. In the early stages of these exposure tests, Oak Ridge National Laboratory preliminary results confirm that the surface reactions of this aggregate proceed more slowly than expected. This finding may indicate that DUAGG/DUCRETE (depleted uranium concrete) casks could have service lives sufficient to meet the projected needs of DOE and the commercial nuclear power industry.

  17. Regional trends in evaporation loss and water yield based on stable isotope mass balance of lakes: The Ontario Precambrian Shield surveys (United States)

    Gibson, J. J.; Birks, S. J.; Jeffries, D.; Yi, Y.


    Stable isotopes of water, oxygen-18 and deuterium, were measured in water samples collected from a network of 300 lakes sampled in six ∼100 km2 blocks (centred at 49.72°N, 91.46°W; 48.49°N, 91.58°W; 50.25°N, 86.62°W; 49.78°N, 83.98°W; 48.24°N, 85.49°W; 47.73, 84.52°W) within Precambrian shield drainages in the vicinity of Lake Superior, northern Ontario, Canada. Additional sampling was also conducted within the Turkey Lakes watershed (47.03°N, 84.38°W), a research basin situated in the Algoma region located 50 km north of Sault Saint Marie, Ontario. The studies were undertaken to gain a better understanding of hydrology and geochemistry of watersheds in the region in order to better predict acid sensitivity of lakes. The main objective of this paper is to describe the hydrologic variations observed based on stable isotope results. Evaporative isotopic enrichment of lake water was found to be systematic across the region, and its deviation from the isotopic composition of precipitation was used to estimate the evaporation/inflow to the lakes as well as runoff (or water yield) based on a simple isotope mass balance model. The analysis illustrates significant variability in the water yield to lakes and reveals a pattern of positively skewed distributions in all six widely spaced blocks, suggesting that a high proportion of lakes have relatively limited runoff whereas relatively few have greater runoff. Such basic information on the drainage structure of an area can be valuable for site-specific hydrologic assessments but also has significant implications for critical loads assessment, as low runoff systems tend to be less buffered and therefore are more sensitive to acidification. Importantly, the Turkey Lakes sampling program also suggests that isotope-based water yield is comparable in magnitude to hydrometric gauging estimates, and also establishes that uncertainty related to stratification can be as high as ±20% or more for individual lakes

  18. Acetylene-based materials in organic photovoltaics. (United States)

    Silvestri, Fabio; Marrocchi, Assunta


    Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Organic photovoltaic systems hold the promise of a lightweight, flexible, cost-effective solar energy conversion platform, which could benefit from simple solution-processing of the active layer. The discovery of semiconductive polyacetylene by Heeger et al. in the late 1970s was a milestone towards the use of organic materials in electronics; the development of efficient protocols for the palladium catalyzed alkynylation reactions and the new conception of steric and conformational advantages of acetylenes have been recently focused the attention on conjugated triple-bond containing systems as a promising class of semiconductors for OPVs applications. We review here the most important and representative (poly)arylacetylenes that have been used in the field. A general introduction to (poly)arylacetylenes, and the most common synthetic approaches directed toward making these materials will be firstly given. After a brief discussion on working principles and critical parameters of OPVs, we will focus on molecular arylacetylenes, (co)polymers containing triple bonds, and metallopolyyne polymers as p-type semiconductor materials. The last section will deal with hybrids in which oligomeric/polymeric structures incorporating acetylenic linkages such as phenylene ethynylenes have been attached onto C(60), and their use as the active materials in photovoltaic devices.

  19. Acetylene-Based Materials in Organic Photovoltaics

    Directory of Open Access Journals (Sweden)

    Fabio Silvestri


    Full Text Available Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Organic photovoltaic systems hold the promise of a lightweight, flexible, cost-effective solar energy conversion platform, which could benefit from simple solution-processing of the active layer. The discovery of semiconductive polyacetylene by Heeger et al. in the late 1970s was a milestone towards the use of organic materials in electronics; the development of efficient protocols for the palladium catalyzed alkynylation reactions and the new conception of steric and conformational advantages of acetylenes have been recently focused the attention on conjugated triple-bond containing systems as a promising class of semiconductors for OPVs applications. We review here the most important and representative (polyarylacetylenes that have been used in the field. A general introduction to (polyarylacetylenes, and the most common synthetic approaches directed toward making these materials will be firstly given. After a brief discussion on working principles and critical parameters of OPVs, we will focus on molecular arylacetylenes, (copolymers containing triple bonds, and metallopolyyne polymers as p-type semiconductor materials. The last section will deal with hybrids in which oligomeric/polymeric structures incorporating acetylenic linkages such as phenylene ethynylenes have been attached onto C60, and their use as the active materials in photovoltaic devices.

  20. In-Beam Background Suppression Shield

    CERN Document Server

    Santoro, V; DiJulio, D D; Ansell, S; Bentley, P M


    The long (3ms) proton pulse of the European Spallation Source (ESS) gives rise to unique and potentially high backgrounds for the instrument suite. In such a source an instrument capabilities will be limited by it's Signal to Noise (S/N) ratio. The instruments with a direct view of the moderator, which do not use a bender to help mitigate the fast neutron background, are the most challenging. For these beam lines we propose the innovative shielding of placing blocks of material directly into the guide system, which allow a minimum attenuation of the cold and thermal fluxes relative to the background suppression. This shielding configuration has been worked into a beam line model using Geant4. We study particularly the advantages of single crystal sapphire and silicon blocks .

  1. Grounding and shielding circuits and interference

    CERN Document Server

    Morrison, Ralph


    Applies basic field behavior in circuit design and demonstrates how it relates to grounding and shielding requirements and techniques in circuit design This book connects the fundamentals of electromagnetic theory to the problems of interference in all types of electronic design. The text covers power distribution in facilities, mixing of analog and digital circuitry, circuit board layout at high clock rates, and meeting radiation and susceptibility standards. The author examines the grounding and shielding requirements and techniques in circuit design and applies basic physics to circuit behavior. The sixth edition of this book has been updated with new material added throughout the chapters where appropriate. The presentation of the book has also been rearranged in order to reflect the current trends in the field.

  2. Shielding analysis of proton therapy accelerators: a demonstration using Monte Carlo-generated source terms and attenuation lengths. (United States)

    Lai, Bo-Lun; Sheu, Rong-Jiun; Lin, Uei-Tyng


    Monte Carlo simulations are generally considered the most accurate method for complex accelerator shielding analysis. Simplified models based on point-source line-of-sight approximation are often preferable in practice because they are intuitive and easy to use. A set of shielding data, including source terms and attenuation lengths for several common targets (iron, graphite, tissue, and copper) and shielding materials (concrete, iron, and lead) were generated by performing Monte Carlo simulations for 100-300 MeV protons. Possible applications and a proper use of the data set were demonstrated through a practical case study, in which shielding analysis on a typical proton treatment room was conducted. A thorough and consistent comparison between the predictions of our point-source line-of-sight model and those obtained by Monte Carlo simulations for a 360° dose distribution around the room perimeter showed that the data set can yield fairly accurate or conservative estimates for the transmitted doses, except for those near the maze exit. In addition, this study demonstrated that appropriate coupling between the generated source term and empirical formulae for radiation streaming can be used to predict a reasonable dose distribution along the maze. This case study proved the effectiveness and advantage of applying the data set to a quick shielding design and dose evaluation for proton therapy accelerators.

  3. Bio-based amphiphilic materials development and applications (United States)

    Farm-based raw materials are increasingly used in the development of amphiphilic materials that have potential applications in the production of a variety of consumer and industrial products, including lubricants. Raw materials of interest include: starches, proteins, fats, oils, and sugars. These ...

  4. Neutron guide shielding for the BIFROST spectrometer at ESS

    DEFF Research Database (Denmark)

    Mantulnikovs, K.; Bertelsen, M.; Cooper-Jensen, C.P.


    We report on the study of fast-neutron background for the BIFROST spectrometer at ESS. We investigate the effect of background radiation induced by the interaction of fast neutrons from the source with the material of the neutron guide and devise a reasonable fast, thermal/cold neutron shielding...... solution for the current guide geometry using McStas and MCNPX. We investigate the effectiveness of the steel shielding around the guide by running simulations with three different steel thicknesses. The same approach is used to study the efficiencies of the steel wall a flat cylinder pierced by the guide...... in the middle and the polyethylene layer. The final model presented here has a 3 cm thick steel shielding around the guide, 30 cm of polyethylene around the shielding, two 5 mm thick B4C layers and a steel wall at position Z = 38 m, being 1 m thick and 10 m in radius. The final model finally proves...

  5. Shielding efficiency of metal hydrides and borohydrides in fusion reactors

    Directory of Open Access Journals (Sweden)

    Singh Vishvanath P.


    Full Text Available Mass attenuation coefficients, mean free paths and exposure buildup factors have been used to characterize the shielding efficiency of metal hydrides and borohydrides, with high density of hydrogen. Gamma ray exposure buildup factors were computed using five-parameter geometric progression fitting at energies 0.015 MeV to15 MeV, and for penetration depths up to 40 mean free paths. Fast-neutron shielding efficiency has been characterized by the effective neutron removal cross-section. It is shown that ZrH2 and VH2 are very good shielding materials for gamma rays and fast neutrons due to their suitable combination of low- and high-Z elements. The present work should be useful for the selection and design of blankets and shielding, and for dose evaluation for components in fusion reactors.

  6. Electromagnetic interference shielding effectiveness of polypropylene/conducting fiber composites (United States)

    Lee, Pyoung-Chan; Kim, Bo-Ram; Jeoung, Sun Kyoung; Kim, Yeung Keun


    Electromagnetic released from the automotive electronic parts is harmful to human body. Electromagnetic interference (EMT) shielding refers to the reflection and/or adsorption of electromagnetic radiation by a material, which thereby acts as a shield against the penetration of the radiation through the shield. Polypropylene (PP)/conductive micro fiber composites containing various fiber contents and fiber length were injection-molded. The effect of fiber content and length on electrical properties of the composites was studied by electrical resistivity and EMT shielding measurements. The through-plane electrical conductivity and dielectric permittivity were obtained by measuring dielectric properties. The EMT shielding effectiveness (SE) was investigated by using S-parameter in the range of 100 ~ 1500 MHz. Reflection, absorption and multiple-reflection are the EMT attenuation mechanisms. From the measurement of S-Parameters, the absorption coefficient, reflection coefficient, and the shielding efficiency of the materials were calculated. The EMT SE of PP/conducing fiber composites is 40 dB over a wide frequency range up to 1.5 GHz, which is higher than that of PP/talc composite used automotive parts, viz. 0 dB.

  7. Reinforcement of Conducting Silver-based Materials

    Directory of Open Access Journals (Sweden)

    Heike JUNG


    Full Text Available Silver is a well-known material in the field of contact materials because of its high electrical and thermal conductivity. However, due to its bad mechanical and switching properties, silver alloys or reinforcements of the ductile silver matrix are required. Different reinforcements, e. g. tungsten, tungsten carbide, nickel, cadmium oxide or tin oxide, are used in different sectors of switches. To reach an optimal distribution of these reinforcements, various manufacturing techniques (e. g. powder blending, preform infiltration, wet-chemical methods, internal oxidation are being used for the production of these contact materials. Each of these manufacturing routes offers different advantages and disadvantages. The mechanical alloying process displays a successful and efficient method to produce particle-reinforced metal-matrix composite powders. This contribution presents the obtained fine disperse microstructure of tungsten-particle-reinforced silver composite powders produced by the mechanical alloying process and displays this technique as possible route to provide feedstock powders for subsequent consolidation processes. DOI:

  8. Radiological evaluation of shielding devices type CPb-m and CPb-g used for radioactive material handling and transportation of CENTIS, Cuba; Evaluacion radiologica de los dispositivos de blindaje tipo CPb-m y CPb-g utilizados para la manipulacion y transportacion de los preparados radiactivos del CENTIS

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Rondon, Manuel; Torres Berdeguez, Mirta B. [Centro de Tecnologia Nuclear, San Jose de las Lajas (Cuba); Hernandez Rivero, Aerulio T.; Gutierrez Ravelo, Romay [Centro de Isotopos, XX (Cuba)


    This work has presented procedures applied for radiological evaluation of gamma shielding devices type CPb-m and CPb-g, used to 30-50 mCi respectively, asseverating a dose rate lower than 2 mSv/h and satisfying the requirements of radiological safety for handling and transportation of radioactive materials. The results has been shown and discussed 10 refs., 3 figs., 2 tabs.

  9. Mn based olivine electrode material with high power and energy. (United States)

    Kim, Jongsoon; Seo, Dong-Hwa; Kim, Sung-Wook; Park, Young-Uk; Kang, Kisuk


    We report the Mn based olivine electrode material with high power and energy. Easier and more frequent nucleation by Fe and Co in Mn-based olivines significantly enhanced the rate capability as evidenced by the electrochemical results.

  10. Biomedical applications of the graphene-based materials. (United States)

    Zhang, Baomei; Wang, Yang; Zhai, Guangxi


    Graphene, a rapidly rising star, has gained extensive research interests lately due to its excellent properties--such as the exceptional optical, electrical, thermal and mechanical features--which are superior to other materials, so it is called "two-dimensional magical materials". This article presents diverse types and various properties of graphene-based materials, and the current methods for the surface modifications of the graphene-based materials are briefly described. In addition, the in vivo and in vitro cytotoxicity of graphene-based materials are comprehensively discussed. What's more, a summary of its biomedical applications such as drug/gene delivery, photothermal therapy, photodynamic therapy and multimodality therapy is also offered. Finally, an outlook of the graphene-based materials and the challenges in this field are briefly discussed.

  11. Carbon-based electrode materials for DNA electroanalysis. (United States)

    Kato, Dai; Niwa, Osamu


    This review addresses recent studies of newly developed carbon-based electrode materials and their use for DNA electroanalysis. Recently, new carbon materials including carbon nanotubes (CNT), graphene and diamond-based nanocarbon electrodes have been actively developed as sensing platforms for biomolecules, such as DNA and proteins. Electrochemical techniques using these new material-based electrodes can provide very simple and inexpensive sensing platforms, and so are expected to be used as one of the "post-light" DNA analysis methods, which include coulometric detection, amperometric detection with electroactive tags or intercalators, and potentiometric detection. DNA electroanalysis using these new carbon materials is summarized in view of recent advances on electrodes.

  12. Design and Implementation of Simultaneous Shield And Repeater Insertion for On-chip Interconnects

    Directory of Open Access Journals (Sweden)

    M. Surendra Goud Mr. Y. Sreenivas Goud


    Full Text Available A Resource based optimization is a new approach for high performance integrated circuits. The method is applied to simultaneous shield and repeater insertion, resulting in minimum coupling noise under power, delay, and area constraints Repeater insertion is a well known design technique to reduce the delay required to propagate a signal along a line. Shielding inserts an additional line between a victim line and an aggressor line. Finally placing a shield beside and inserting repeaters along a victim line and are chosen to exemplify the resource based optimization process. In the active shielding architecture shield driving circuits as 4:1 multiplexer, full adder, multipliers are inserted. The power consumption of active shielding architecture is observed to be approximately 20% less compare to passive shielding architecture. The main aim of this is minimize the coupling noise under power, delay, and area constraints

  13. Artificial atoms based on correlated materials (United States)

    Mannhart, J.; Boschker, H.; Kopp, T.; Valentí, R.


    Low-dimensional electron systems fabricated from quantum matter have in recent years become available and are being explored with great intensity. This article gives an overview of the fundamental properties of such systems and summarizes the state of the field. We furthermore present and consider the concept of artificial atoms fabricated from quantum materials, anticipating remarkable scientific advances and possibly important applications of this new field of research. The surprising properties of these artificial atoms and of molecules or even of solids assembled from them are presented and discussed.

  14. Polymerization shrinkage of flowable resin-based restorative materials


    Stavridakis, Minos M; Dietschi, Didier; Krejci, Ivo


    This study measured the linear polymerization displacement and polymerization forces induced by polymerization shrinkage of a series of flowable resin-based restorative materials. The materials tested were 22 flowable resin-based restorative materials (Admira Flow, Aelite Flow, Aeliteflow LV, Aria, Crystal Essence, Definite Flow, Dyract Flow, Filtek Flow, FloRestore, Flow-it, Flow-Line, Freedom, Glacier, OmegaFlo, PermaFlo, Photo SC, Revolution 2, Star Flow, Synergy Flow, Tetric Flow, Ultrase...

  15. Shielding synchrotron light sources: Advantages of circular shield walls tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, S.L. [Design and Accelerator Operations Consulting, 568 Wintergreen Ct Ridge, NY 11961 (United States); Ghosh, V.J.; Breitfeller, M. [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States)


    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produce significantly higher neutron component dose to the experimental floor than lower energy injection and ramped operations. High energy neutrons produced in the forward direction from thin target beam losses are a major component of the dose rate outside the shield walls of the tunnel. The convention has been to provide thicker 90° ratchet walls to reduce this dose to the beam line users. We present an alternate circular shield wall design, which naturally and cost effectively increases the path length for this forward radiation in the shield wall and thereby substantially decreasing the dose rate for these beam losses. This shield wall design will greatly reduce the dose rate to the users working near the front end optical components but will challenge the beam line designers to effectively utilize the longer length of beam line penetration in the shield wall. Additional advantages of the circular shield wall tunnel are that it's simpler to construct, allows greater access to the insertion devices and the upstream in tunnel beam line components, as well as reducing the volume of concrete and therefore the cost of the shield wall.

  16. Shielding synchrotron light sources: Advantages of circular shield walls tunnels (United States)

    Kramer, S. L.; Ghosh, V. J.; Breitfeller, M.


    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produce significantly higher neutron component dose to the experimental floor than lower energy injection and ramped operations. High energy neutrons produced in the forward direction from thin target beam losses are a major component of the dose rate outside the shield walls of the tunnel. The convention has been to provide thicker 90° ratchet walls to reduce this dose to the beam line users. We present an alternate circular shield wall design, which naturally and cost effectively increases the path length for this forward radiation in the shield wall and thereby substantially decreasing the dose rate for these beam losses. This shield wall design will greatly reduce the dose rate to the users working near the front end optical components but will challenge the beam line designers to effectively utilize the longer length of beam line penetration in the shield wall. Additional advantages of the circular shield wall tunnel are that it's simpler to construct, allows greater access to the insertion devices and the upstream in tunnel beam line components, as well as reducing the volume of concrete and therefore the cost of the shield wall.

  17. Densified ultra-light cement-based materials

    DEFF Research Database (Denmark)

    Esteves, Luis Pedro


    be used as a “clean technology” in the production of cement-based materials for structural applications with a low carbon footprint. This paper describes the principles of this concept coupled with experimental results on the basic properties of this enhanced type of cement-based materials with combined...

  18. An Analysis of Contracting Actions by United States Based Department of Defense Organizations to Support Operations Desert Shield and Desert Storm (United States)


    Personal Interviews . . . . .... 36 Use of the Delphi Method . . . . . .... 37 Discussion of Investigative Questions . . . 39 Investigative Questions...the end of Desert Storm. Prior to Desert Shield the two manufacturers of injectors for atropine, a nerve agent antidote, were producing 60,000 units...two-stage approach was the formal phase, in which the Delphi technique was determined to be appropriate (Emory and Cooper, 1991:149). The data was

  19. News from the Library: Facilitating access to a program for radiation shielding - the Library can help

    CERN Multimedia

    CERN Library


    MicroShield® is a comprehensive photon/gamma ray shielding and dose assessment programme. It is widely used for designing shields, estimating source strength from radiation measurements, minimising exposure to people, and teaching shielding principles.   Integrated tools allow the graphing of results, material and source file creation, source inference with decay (dose-to-Bq calculations accounting for decay and daughter buildup), the projection of exposure rate versus time as a result of decay, access to material and nuclide data, and decay heat calculations. The latest version is able to export results using Microsoft Office (formatted and colour-coded for readability). Sixteen geometries accommodate offset dose points and as many as ten standard shields plus source self-shielding and cylinder cladding are available. The library data (radionuclides, attenuation, build-up and dose conversion) reflect standard data from ICRP 38 and 107* as well as ANSI/ANS standards and RSICC publicat...

  20. Using remote sensing techniques and field-based structural analysis to explore new gold and associated mineral sites around Al-Hajar mine, Asir terrane, Arabian Shield (United States)

    Sonbul, Abdullah R.; El-Shafei, Mohamed K.; Bishta, Adel Z.


    Modern earth resource satellites provide huge amounts of digital imagery at different resolutions. These satellite imageries are considered one of the most significant sources of data for mineral exploration. Image processing techniques were applied to the exposed rocks around the Al-Aqiq area of the Asir terrane in the southern part of the Arabian Shield. The area under study has two sub-parallel N-S trending metamorphic belts of green-schist facies. The first belt is located southeast of Al-Aqiq, where the Al-Hajar Gold Mine is situated. It is essentially composed of metavolcanics and metasedimentary rocks, and it is intruded by different plutonic rocks of primarily diorite, syenite and porphyritic granite. The second belt is located northwest of Al-Aqiq, and it is composed of metavolcanics and metasedimentary rocks and is intruded by granite bodies. The current study aimed to distinguish the lithological units, detect and map the alteration zones, and extract the major fault lineaments around the Al-Hajar gold prospect. Digital satellite imageries, including Landsat 7 ETM + multispectral and panchromatic and SPOT-5 were used in addition to field verification. Areas with similar spectral signatures to the prospect were identified in the nearby metamorphic belt; it was considered as a target area and was inspected in the field. The relationships between the alteration zones, the mineral deposits and the structural elements were used to locate the ore-bearing zones in the subsurface. The metasedimentary units of the target area showed a dextral-ductile shearing top-to-the-north and the presence of dominant mineralized quartz vein-system. The area to the north of the Al-Hajar prospect showed also sub-parallel shear zones along which different types of alterations were detected. Field-based criteria such as hydrothermal breccia, jasper, iron gossans and porphyritic granite strongly indicate the presence of porphyry-type ore deposits in Al-Hajar metamorphic belt that

  1. Intermetallic-based high-temperature materials

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.


    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminides are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  2. Intermetallic-Based High-Temperature Materials

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.


    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminizes are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  3. A Novel Radiation Shielding Material Project (United States)

    National Aeronautics and Space Administration — In order to safely explore space, humans must be protected from radiation. There are 2 predominant sources of extraterrestrial ionizing radiation, namely, Galactic...

  4. Novel Concepts for Radiation Shielding Materials Project (United States)

    National Aeronautics and Space Administration — It is critical that safety factors be maximized with respect to long duration, extraterrestrial space flight. Any significant improvement in radiation protection...

  5. A Radiation Shielding Code for Spacecraft and Its Validation (United States)

    Shinn, J. L.; Cucinotta, F. A.; Singleterry, R. C.; Wilson, J. W.; Badavi, F. F.; Badhwar, G. D.; Miller, J.; Zeitlin, C.; Heilbronn, L.; Tripathi, R. K.


    The HZETRN code, which uses a deterministic approach pioneered at NASA Langley Research Center, has been developed over the past decade to evaluate the local radiation fields within sensitive materials (electronic devices and human tissue) on spacecraft in the space environment. The code describes the interactions of shield materials with the incident galactic cosmic rays, trapped protons, or energetic protons from solar particle events in free space and low Earth orbit. The content of incident radiations is modified by atomic and nuclear reactions with the spacecraft and radiation shield materials. High-energy heavy ions are fragmented into less massive reaction products, and reaction products are produced by direct knockout of shield constituents or from de-excitation products. An overview of the computational procedures and database which describe these interactions is given. Validation of the code with recent Monte Carlo benchmarks, and laboratory and flight measurement is also included.

  6. Shape Effect Analysis of Aluminum Projectile Impact on Whipple Shields (United States)

    Carrasquilla, Maria J.; Miller, Joshua E.


    respect to their mass, size, and material composition needs to be summarized in a form that can be used in MMOD analysis. The mechanism that brings these fragment traits into MMOD analysis is through ballistic limit equations (BLE) that have been developed largely for a few types of materials1. As a BLE provides the failure threshold for a shield or spacecraft component based on parameters such as the projectile impact velocity and size, and the target's materials, thickness, and configuration, it is used to design protective shields for spacecraft such as Whipple shields (WS) to an acceptable risk level. The majority of experiments and simulations to test shields and validate BLEs have, heretofore, largely used spheres as the impactor, not properly reflecting the irregular shapes of MMOD. This shortfall has motivated a numerical impact analysis study of HVI involving non-spherical geometries to identify key parameters that environment models should provide.

  7. The blattodeas.s. (Insecta, dictyoptera) of the Guiana shield. (United States)

    Evangelista, Dominic A; Chan, Kimberly; Kaplan, Kayla L; Wilson, Megan M; Ware, Jessica L


    Here we provide a checklist of cockroach species known from areas within the Guiana Shield based on literature records and new field collection. We give records of sixteen species collected in Guyana, eight of which are new records for Guyana and one of which is a new generic record for the entire Guiana Shield. We also provide a description for a geographically disparate species of Calhypnorna Stal, and the new species Xestoblattaberenbaumae. The complete checklist contains 234 species of Blattodeas.s. currently known in the shield. This checklist shows particularly low richness in Guianan Venezuela, Roraima and Amapa Brazil, but this is likely an artifact due to under-sampling. Indeed, based on previously published data and current fieldwork, we believe that most regions of the Guiana Shield are under-sampled for cockroaches. Despite this, French Guiana (151 spp.) and Suriname (136 spp.) rank as the second and sixth most species dense faunas of cockroaches in the neotropics.

  8. Research on Shielded Keywords Based on Cascaded Hidden Markov Model%基于层叠隐马模型的屏蔽关键词研究

    Institute of Scientific and Technical Information of China (English)



    The information age brings a huge improvement in people's lives,but also accompanied by a series of problems arising,in which how to filter a large amount of information the network's remarks generated is a major difficulty. The traditional method of shiel-ding has low efficiency and is not accurate enough,so propose a new keyword shielding technology. Mainly use binary syntax model combined with layered hidden Markov model segmentation techniques,first utilize binary syntax model to get the constitute probability of the common words and keywords in a large corpus,creating a dictionary of common words and keywords classified,then combined casca-ding hidden Markov model for the specific sentence word processing,calculate the probability of its keywords shield for segmented result, finally get a scientific shielding probability,which can greatly improve the accuracy of keyword shield.%信息时代给人们的生活带来巨大改善,但同时也伴随一系列问题的产生,其中如何对网络中产生的大数据量的言论信息进行过滤的问题是研究的一大难点。传统的屏蔽法效率较低而且不够准确,因此文中提出了一种新的关键词屏蔽技术。主要采用二元语法模型结合层叠隐马可夫分词技术,首先运用二元语法模型在大量语料中得到普通词和关键词的构成概率,建立一个有普通词和关键词分类的词典,再结合层叠隐马可夫模型对具体句子进行分词处理,对分词后的结果计算其关键词屏蔽概率,最终得到一个科学的屏蔽概率,可以大大提高关键词屏蔽的准确性。

  9. Hybrid Shielding for Magnetic Fields (United States)

    Mullins, David; Royal, Kevin


    Precision symmetry measurements such as the search for the electric dipole moment of the neutron require magnetic shielding rooms to reduce the ambient field to the pT scale. The massive mu-metal sheets and large separation between layers make these shield rooms bulky and expensive. Active field cancellation systems used to reduce the surrounding field are limited in uniformity of cancellation. A novel approach to reducing the space between shield layers and increasing the effectiveness of active cancellation is to combine the two systems into a hybrid system, with active and passive layers interspersed. We demonstrate this idea in a prototype with an active layer sandwiched between two passive layers of shielding.

  10. Radiation shielding for neutron guides (United States)

    Ersez, T.; Braoudakis, G.; Osborn, J. C.


    Models of the neutron guide shielding for the out of bunker guides on the thermal and cold neutron beam lines of the OPAL Reactor (ANSTO) were constructed using the Monte Carlo code MCNP 4B. The neutrons that were not reflected inside the guides but were absorbed by the supermirror (SM) layers were noted to be a significant source of gammas. Gammas also arise from neutrons absorbed by the B, Si, Na and K contained in the glass. The proposed shielding design has produced compact shielding assemblies. These arrangements are consistent with safety requirements, floor load limits, and cost constraints. To verify the design a prototype was assembled consisting of 120 mm thick Pb(96%)Sb(4%) walls resting on a concrete block. There was good agreement between experimental measurements and calculated dose rates for bulk shield regions.

  11. Diatom-Based Material Production Demonstration (United States)


    diatom cell walls. ............................................................... 19! Fig. 12 Setup for sieving diatom cell walls on the left, metal ...of diatom biomass. .............. 15! Table 4 P1 and P2 step details for cleaning of diatom cell walls at the farm. .................. 19! Table 5...are the most silicified and have the most intricate structures . Diatom valves are used to identify diatoms based on their morphology. Diatom

  12. Determination of dosimetric parameters for shielded 153Gd source in prostate cancer brachytherapy (United States)

    Ghorbani, Mahdi; Ghatei, Najmeh; Mehrpouyan, Mohammad; Meigooni, Ali S.; Shahraini, Ramin


    Abstract Background Interstitial rotating shield brachytherapy (I-RSBT) is a recently developed method for treatment of prostate cancer. In the present study TG-43 dosimetric parameters of a 153Gd source were obtained for use in I-RSBT. Materials and methods A 153Gd source located inside a needle including a Pt shield and an aluminum window was simulated using MCNPX Monte Carlo code. Dosimetric parameters of this source model, including air kerma strength, dose rate constant, radial dose function and 2D anisotropy function, with and without the shields were calculated according to the TG-43 report. Results The air kerma strength was found to be 6.71 U for the non-shielded source with 1 GBq activity. This value was found to be 0.04 U and 6.19 U for the Pt shield and Al window cases, respectively. Dose rate constant for the non-shielded source was found to be 1.20 cGy/(hU). However, for a shielded source with Pt and aluminum window, dose rate constants were found to be 0.07 cGy/(hU) and 0.96 cGy/(hU), on the shielded and window sides, respectively. The values of radial dose function and anisotropy function were tabulated for these sources. Additionally, isodose curves were drawn for sources with and without shield, in order to evaluate the effect of shield on dose distribution. Conclusions Existence of the Pt shield may greatly reduce the dose to organs at risk and normal tissues which are located toward the shielded side. The calculated air kerma strength, dose rate constant, radial dose function and 2D anisotropy function data for the 153Gd source for the non-shielded and the shielded sources can be used in the treatment planning system (TPS). PMID:28265239

  13. Evaluation of the Prevalence and Utility of Gonad Shielding in Pediatrics Undergoing Pelvic X-Ray

    Directory of Open Access Journals (Sweden)

    Vahid Karami


    Full Text Available Background: Gonad shielding has been recommended during pelvic x-rays since the 1950s. The popular method of gonad shielding is placement a lead shield in the midline of the pelvis. The aim of this study was to evaluate the prevalence and utility of gonad shielding in pediatrics undergoing pelvic x-rays.Materials and MethodsFollowing study approval, we retrospectively retrieved data from the digital image library of ten radiology depertments of Khuzestan provience-Iran to identify pediatric patients who underwent pelvic x-ray (anteriorposterior [AP] view. All the images were reviewed for the probable evidence of gonad shield. If there was evidence of shielding, the accuracy positioning of the shield was also investigated by a single assistant radiologist.ResultsIn all 1745 pelvic x-rays (942 girls and 803 boys were identified of which the shield was present in 51 (5.41% radiographs of girls and 132 (16.43% radiographs of boys. When a shield was present; the shields has adequate positioning only in 8 (15.68% radiographs in girls and 59 radiographs in boys. Inaccurate placement and absence of gonad shields were more common in girls than the boys. Due to the shield has concealed the anatomical criteria of the pelvis, retakes of the examination was required in 11 (21.56% radiographs of girls and 14 (10.6% radiographs of boys.ConclusionThe current methods of gonad shielding in girls pelvic x-ray was not effective nor is justifiable. We  no longer advocate of gonad shielding during girls pelvic x-ray. However in boys it is controversial and depends on the skill and effort of radiographers.

  14. Thermal neutron shield and method of manufacture

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, Bert Clayton; Brindza, Paul Daniel


    A thermal neutron shield comprising boron shielding panels with a high percentage of the element Boron. The panel is least 46% Boron by weight which maximizes the effectiveness of the shielding against thermal neutrons. The accompanying method discloses the manufacture of boron shielding panels which includes enriching the pre-cursor mixture with varying grit sizes of Boron Carbide.


    Institute of Scientific and Technical Information of China (English)

    X.C. Li; W.X. Zhu; G. Chen; D.S. Mei; J. Zhang; K.M. Chen


    An artificial neural networks(ANNs) based gear material selection hybrid intelligent system is established by analyzing the individual advantages and weakness of expert system (ES) and ANNs and the applications in material select of them. The system mainly consists of tow parts: ES and ANNs. By being trained with much data samples,the back propagation (BP) ANN gets the knowledge of gear materials selection, and is able to inference according to user input. The system realizes the complementing of ANNs and ES. Using this system, engineers without materials selection experience can conveniently deal with gear materials selection.

  16. Shielding factors of ions in rock-salt crystals (United States)

    Michihiro, Y.; Mahan, G. D.


    The calculation of the quadrupole shielding factor of closed-shell ions in crystalline solids with rock-salt structure is done based on the self-consistent-field local-density approximation, modified Sternheimer equation, and spherical solid model. A significant reduction of the values of the quadrupole shielding factor is found for the anions, and the amount of the reduction is different in different crystals.

  17. Surface properties of copper based cermet materials

    Energy Technology Data Exchange (ETDEWEB)

    Voinea, M. [The Centre: Product Design for Sustainable Development, Transilvania University of Brasov, Eroilor 29, 500036 (Romania)], E-mail:; Vladuta, C.; Bogatu, C.; Duta, A. [The Centre: Product Design for Sustainable Development, Transilvania University of Brasov, Eroilor 29, 500036 (Romania)


    The paper presents the characterization of the surface properties of copper based cermets obtained by two different techniques: spray pyrolysis deposition (SPD) and electrodeposition. Copper acetate was used as precursor of Cu/CuO{sub x} cermet. The surface morphology was tailored by adding copolymers of maleic anhydride with controlled hydrophobia. The films morphology of Cu/CuO{sub x} was assessed using contact angle measurements and AFM analysis. The porous structures obtained via SPD lead to higher liquid adsorption rate than the electrodeposited films. A highly polar liquid - water is recommended as testing liquid in contact angle measurements, for estimating the porosity of copper based cermets, while glycerol can be used to distinguish among ionic and metal predominant structures. Thus, contact angle measurements can be used for a primary evaluation of the films morphology and, on the other hand, of the ratio between the cermet components.

  18. Emerging Ceramic-based Materials for Dentistry (United States)

    Denry, I.; Kelly, J.R.


    Our goal is to give an overview of a selection of emerging ceramics and issues for dental or biomedical applications, with emphasis on specific challenges associated with full-contour zirconia ceramics, and a brief synopsis on new machinable glass-ceramics and ceramic-based interpenetrating phase composites. Selected fabrication techniques relevant to dental or biomedical applications such as microwave sintering, spark plasma sintering, and additive manufacturing are also reviewed. Where appropriate, the authors have added their opinions and guidance. PMID:25274751

  19. Electrical and electromagnetic interference shielding characteristics of GNP/UHMWPE composites (United States)

    Al-Saleh, Mohammed H.


    Conductive polymer composites (CPC) are attractive materials for a wide range of applications because of their weight, corrosion resistivity, design flexibility and low cost. In the present work, the electrical and electromagnetic interference (EMI) shielding characteristics of graphene nanoplatelets (GNP)/ultrahigh molecular weight polyethylene (UHMWPE) composites filled with up to 40 wt% GNP were investigated. In addition, the intrinsic conductivity of the GNP network was estimated based on the statistical power law and the rule of mixtures for randomly oriented filler particles in insulating matrix. Due to the formation of a segregated conductive network at the external surface of UHMWPE powder, an electrical percolation threshold of between 2 and 3 wt% GNP was obtained. At GNP loading of 15 wt%, the composite exhibited an EMI shielding effectiveness of 33 dB, corresponding to 99.95% blocking of the EMI.

  20. Monte Carlo simulations of a D-T neutron generator shielding for landmine detection

    Energy Technology Data Exchange (ETDEWEB)

    Reda, A.M., E-mail: [College of Science, Shaqra University, Al-Dawadme, P.O. Box 1040 (Saudi Arabia)


    Shielding for a D-T sealed neutron generator has been designed using the MCNP5 Monte Carlo radiation transport code. The neutron generator will be used in field for the detection of explosives, landmines, drugs and other 'threat' materials. The optimization of the detection of buried objects was started by studying the signal-to-noise ratio for different geometric conditions. - Highlights: > A landmine detection system based on neutron fast/slow analysis has been designed. > Shielding for a D-T sealed neutron generator tube has been designed using Monte Carlo radiation transport code. > Detection of buried objects was started by studying the signal-to-noise ratio for different geometric conditions. > The signal-to-background ratio optimized at one position for all depths.

  1. Spacecraft Shielding: An Experimental Comparison Between Open Cell Aluminium Foam Core Sandwich Panel Structures and Whipple Shielding. (United States)

    Pasini, D. L. S.; Price, M. C.; Burchell, M. J.; Cole, M. J.


    Spacecraft shielding is generally provided by metallic plates in a Whipple shield type configuration [1] where possible. However, mission restrictions such as spacecraft payload mass, can prevent the inclusion of a dedicated protective structure for prevention against impact damage from micrometeoroids. Due to this, often the spacecraft's primary structure will act as the de facto shield. This is commonly an aluminium honeycomb backed with either glass fibre reinforced plastic (GFRP) or aluminium faceplates [2]. Such materials are strong, lightweight and relatively cheap due to their abundance used within the aerospace industry. However, these materials do not offer the best protection (per unit weight) against hypervelocity impact damage. A new material for shielding (porous aluminium foam [3]) is suggested for low risk space missions. Previous studies by NASA [4] have been performed to test this new material against hypervelocity impacts using spherical aluminium projectiles. This showed its potential for protection for satellites in Earth orbit, against metallic space debris. Here we demonstrate the material's protective capabilities against micrometeoroids, using soda-lime glass spheres as projectiles to accurately gauge its potential with relation to silicatious materials, such as micrometeoroids and natural solar system debris. This is useful for spacecraft missions beyond Earth orbit where solar system materials are the dominant threat (via hypervelocity impacts) to the spacecraft, rather than manmade debris.

  2. Development trends in Conductive Nano-Composites for Radiation Shielding

    Directory of Open Access Journals (Sweden)

    Vishal Udmale


    Full Text Available Our paper reviews the use of conductive polymer composite materials in various applications for semi conductive, static-dissipative, anti-corrosive, electromagnetic interference (EMI shielding and stealth composite coatings. The composite consists of conductive fillers and the insulating polymer network. The composite becomes electrically conductive as the filler content exceeds a certain critical value, generally called as Percolation Threshold Value (PTV. The PTV for a particular polymer composite can be drastically reduced by using nano-sized conductive fillers. The higher the aspect ratio (length:width of the nano-fillers, the lower is the concentration for achieving the PTV. Traditionally the metals, carbon-black particles and alloys have been used as electrically conductive fillers; however, very high level of these fillers can be detrimental for the process ability, surface quality of the material, density, the cost and mechanical properties of the composite. By the use of nano conductive fillers, good conductivity will be achieved while retaining the original properties. Recently, one and two dimensional nano-creatures based on carbon such as carbon nanotubes and graphene respectively have received significant attention, due to their outstanding thermal, electronic and mechanical properties. In this paper we have compared different conductive filler materials, their dispersion techniques, and compatibility in polymer matrix and suitability in various above mentioned applications. The proliferation of mobile towers and electronic devices in the world results in harmful EMI and radio frequency interference (RFI ultimately causing operational malfunction to electronic devises and also harmful to living beings, signifies the importance of this detailed review for EMI/RFI shielding applications.

  3. Upgrade of the LHC magnet interconnections thermal shielding (United States)

    Musso, Andrea; Barlow, Graeme; Bastard, Alain; Charrondiere, Maryline; Chrul, Anna; Damianoglou, Dimitrios; Deferne, Guy; Dib, Gaëlle; Duret, Max; Guinchard, Michael; Prin, Hervé; Strychalski, Michał; Craen, Arnaud Vande; Villiger, Gilles; Wright, Loren


    The about 1700 interconnections (ICs) between the Large Hadron Collider (LHC) superconducting magnets include thermal shielding at 50-75 K, providing continuity to the thermal shielding of the magnet cryostats to reduce the overall radiation heat loads to the 1.9 K helium bath of the magnets. The IC shield, made of aluminum, is conduction-cooled via a welded bridge to the thermal shield of the adjacent magnets which is actively cooled. TIG welding of these bridges made in the LHC tunnel at installation of the magnets induced a considerable risk of fire hazard due to the proximity of the multi-layer insulation of the magnet shields. A fire incident occurred in one of the machine sectors during machine installation, but fortunately with limited consequences thanks to prompt intervention of the operators. LHC is now undergoing a 2 years technical stop during which all magnet's ICs will have to be opened to consolidate the magnet electrical connections. The IC thermal shields will therefore have to be removed and re-installed after the work is completed. In order to eliminate the risk of fire hazard when re-welding, it has been decided to review the design of the IC shields, by replacing the welded bridges with a mechanical clamping which also preserves its thermal function. An additional advantage of this new solution is the ease in dismantling for maintenance, and eliminating weld-grinding operations at removal needing radioprotection measures because of material activation after long-term operation of the LHC. This paper describes the new design of the IC shields and in particular the theoretical and experimental validation of its thermal performance. Furthermore a status report of the on-going upgrade work in the LHC is given.

  4. Upgrade of the LHC magnet interconnections thermal shielding

    Energy Technology Data Exchange (ETDEWEB)

    Musso, Andrea; Barlow, Graeme; Bastard, Alain; Charrondiere, Maryline; Deferne, Guy; Dib, Gaëlle; Duret, Max; Guinchard, Michael; Prin, Hervé; Craen, Arnaud Vande; Villiger, Gilles [CERN European Organization for Nuclear Research, Meyrin 1211, Geneva 23, CH (Switzerland); Chrul, Anna [The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul.Radzikowskiego 152, 31-324 Krakow (Poland); Damianoglou, Dimitrios [NTUA National Technical University of Athens, Heeron Polytechniou 9, 15780 Zografou (Greece); Strychalski, Michał [Wroclaw University of Technology, Faculty of Mechanical and Power Engineering, Wyb. Wyspianskiego 27, Wroclaw, 50-370 (Poland); Wright, Loren [Lancaster University, Bailrigg, Lancaster, LA1 4YW (United Kingdom)


    The about 1700 interconnections (ICs) between the Large Hadron Collider (LHC) superconducting magnets include thermal shielding at 50-75 K, providing continuity to the thermal shielding of the magnet cryostats to reduce the overall radiation heat loads to the 1.9 K helium bath of the magnets. The IC shield, made of aluminum, is conduction-cooled via a welded bridge to the thermal shield of the adjacent magnets which is actively cooled. TIG welding of these bridges made in the LHC tunnel at installation of the magnets induced a considerable risk of fire hazard due to the proximity of the multi-layer insulation of the magnet shields. A fire incident occurred in one of the machine sectors during machine installation, but fortunately with limited consequences thanks to prompt intervention of the operators. LHC is now undergoing a 2 years technical stop during which all magnet's ICs will have to be opened to consolidate the magnet electrical connections. The IC thermal shields will therefore have to be removed and re-installed after the work is completed. In order to eliminate the risk of fire hazard when re-welding, it has been decided to review the design of the IC shields, by replacing the welded bridges with a mechanical clamping which also preserves its thermal function. An additional advantage of this new solution is the ease in dismantling for maintenance, and eliminating weld-grinding operations at removal needing radioprotection measures because of material activation after long-term operation of the LHC. This paper describes the new design of the IC shields and in particular the theoretical and experimental validation of its thermal performance. Furthermore a status report of the on-going upgrade work in the LHC is given.

  5. Design of Reflective, Photonic Shields for Atmospheric Reentry (United States)

    Komarevskiy, Nikolay; Shklover, Valery; Braginsky, Leonid; Hafner, Christian; Fabrichnaya, Olga; White, Susan; Lawson, John


    We present the design of one-dimensional photonic crystal structures, which can be used as omnidirectional reflecting shields against radiative heating of space vehicles entering the Earth's atmosphere. This radiation is approximated by two broad bands centered at visible and near-infrared energies. We applied two approaches to find structures with the best omnidirectional reflecting performance. The first approach is based on a band gap analysis and leads to structures composed of stacked Bragg mirrors. In the second approach, we optimize the structure using an evolutionary strategy. The suggested structures are compared with a simple design of two stacked Bragg mirrors. Choice of the constituent materials for the layers as well as the influence of interlayer diffusion at high temperatures are discussed.

  6. Three Dimensional Forming Simulation of the Shielded Slot Plate for the MCFC Using a Ductile Fracture Criterion (United States)

    Lee, C. H.; Yang, D. Y.; Lee, S. R.; Chang, I. G.; Lee, T. W.


    The shielded slot plate, which has a sheared corrugated trapezoidal pattern, is a component of the metallic bipolar plate for the molten carbonate fuel cell (MCFC). In order to increase the efficiency of the fuel cell, the unit cell of the shielded slot plate should have a relatively large upper area. Additionally, defects from the forming process should be minimized. In order to simulate the slitting process, whereby sheared corrugated patterns are formed, ductile fracture criteria based on the histories of stress and strain are employed. The user material subroutine VUMAT is employed for implementation of the material and ductile fracture criteria in the commercial FEM software ABAQUS. The variables of the ductile fracture criteria were determined by comparing the simulation results and the experimental results of the tension test and the shearing test. Parametric studies were conducted to determine the critical value of the ductile fracture criterion. Employing these ductile fracture criteria, the three dimensional forming process of the shielded slot plate was numerically simulated. The effects of the slitting process in the forming process of the shielded slot plate were analyzed through a FEM simulation and experimental studies. Finally, experiments involving microscopic and macroscopic observations were conducted to verify the numerical simulations of the 3-step forming process.

  7. Surface protection in bio-shields via a functional soft skin layer: Lessons from the turtle shell. (United States)

    Shelef, Yaniv; Bar-On, Benny


    The turtle shell is a functional bio-shielding element, which has evolved naturally to provide protection against predator attacks that involve biting and clawing. The near-surface architecture of the turtle shell includes a soft bi-layer skin coating - rather than a hard exterior - which functions as a first line of defense against surface damage. This architecture represents a novel type of bio-shielding configuration, namely, an inverse structural-mechanical design, rather than the hard-coated bio-shielding elements identified so far. In the current study, we used experimentally based structural modeling and FE simulations to analyze the mechanical significance of this unconventional protection architecture in terms of resistance to surface damage upon extensive indentations. We found that the functional bi-layer skin of the turtle shell, which provides graded (soft-softer-hard) mechanical characteristics to the bio-shield exterior, serves as a bumper-buffer mechanism. This material-level adaptation protects the inner core from the highly localized indentation loads via stress delocalization and extensive near-surface plasticity. The newly revealed functional bi-layer coating architecture can potentially be adapted, using synthetic materials, to considerably enhance the surface load-bearing capabilities of various engineering configurations.

  8. Propagation law of impact elastic wave based on specific materials

    Directory of Open Access Journals (Sweden)

    Chunmin CHEN


    Full Text Available In order to explore the propagation law of the impact elastic wave on the platform, the experimental platform is built by using the specific isotropic materials and anisotropic materials. The glass cloth epoxy laminated plate is used for anisotropic material, and an organic glass plate is used for isotropic material. The PVDF sensors adhered on the specific materials are utilized to collect data, and the elastic wave propagation law of different thick plates and laminated plates under impact conditions is analyzed. The Experimental results show that in anisotropic material, transverse wave propagation speed along the fiber arrangement direction is the fastest, while longitudinal wave propagation speed is the slowest. The longitudinal wave propagation speed in anisotropic laminates is much slower than that in the laminated thick plates. In the test channel arranged along a particular angle away from the central region of the material, transverse wave propagation speed is larger. Based on the experimental results, this paper proposes a material combination mode which is advantageous to elastic wave propagation and diffusion in shock-isolating materials. It is proposed to design a composite material with high acoustic velocity by adding regularly arranged fibrous materials. The overall design of the barrier material is a layered structure and a certain number of 90°zigzag structure.

  9. Resin-based composite as a direct esthetic restorative material. (United States)

    Malhotra, Neeraj; Mala, Kundabala; Acharya, Shashirashmi


    The search for an ideal esthetic material for tooth restoration has resulted in significant improvements in both materials and the techniques for using them. Various resin-based composite (RBC) materials have recently been introduced into the market that offer improved esthetic and physical properties. This article reviews RBCs, including their compositions, advantages, and disadvantages, that are contemporary to today's clinical practice as well as those that are under research consideration and/ or in clinical trial phase.

  10. Graphene-Based Carbon Materials for Electrochemical Energy Storage

    Directory of Open Access Journals (Sweden)

    Fei Liu


    Full Text Available Because of their unique 2D structure and numerous fascinating properties, graphene-based materials have attracted particular attention for their potential applications in energy storage devices. In this review paper, we focus on the latest work regarding the development of electrode materials for batteries and supercapacitors from graphene and graphene-based carbon materials. To begin, the advantages of graphene as an electrode material and the existing problems facing its use in this application will be discussed. The next several sections deal with three different methods for improving the energy storage performance of graphene: the restacking of the nanosheets, the doping of graphene with other elements, and the creation of defects on graphene planes. State-of-the-art work is reviewed. Finally, the prospects and further developments in the field of graphene-based materials for electrochemical energy storage are discussed.

  11. Listener: a probe into information based material specification

    DEFF Research Database (Denmark)

    Ramsgaard Thomsen, Mette; Karmon, Ayelet


    This paper presents the thinking and making of the architectural research probe Listener. Developed as an interdisciplinary collaboration between textile design and architecture, Listener explores how information based fabrication technologies are challenging the material practices of architecture....... The paper investigates how textile design can be understood as a model for architectural production providing new strategies for material specification and allowing the thinking of material as inherently variegated and performative. The paper traces the two fold information based strategies present...... in the Listener project. Firstly, the paper presents the design strategy leading to the development of bespoke interfaces between parametric design and CNC based textile fabrication. Secondly, by integrating structural and actuated materials the paper presents the making of a new class of materials...

  12. 基于蒙特卡罗的小尺度参考辐射装置屏蔽研究%Shielding research of minitype reference radiation device based on Monte Carlo simulation

    Institute of Scientific and Technical Information of China (English)

    徐阳; 魏彪; 毛本将; 刘易鑫; 冯鹏


    针对移动式小尺度参考辐射(MRR)装置(移动式校准装置),在进行射线辐射剂量测量的仪器仪表标定或刻度时,应满足其辐射屏蔽安全限值5μSv/h 的屏蔽技术要求,采用蒙特卡罗输运程序 MCNP,开展了移动式小尺度参考辐射装置表面剂量场屏蔽的模拟计算和研究分析工作。研究结果表明,通过 MCNP 模拟的屏蔽设计方法可以详尽反映 MRR 装置各个表面的剂量分布特征和规律,实现移动式小尺度参考辐射装置屏蔽设计,采用的铅钢材料复合屏蔽方案能够保证装置硬度且显著地减轻屏蔽体的重量,最终获取的优化MRR 屏蔽箱体重量约为271.9 kg。%When applied the minitype reference radiation (MRR)to calibrate gamma ray dosimeters,the shielding structure of the MRR should meet the shielding technique demand,in which the limit dose rate of the outside surface of the MRR must be lower than 5 μSv/h.In order to optimize the shielding design of the MRR,Monte Carlo particle transport code MCNP is em-ployed to simulate and analyze the dose distribution of the outside surface of the MRR.The results show that the dose distribution of each surface of the MRR can be described in detail with MCNP and it is conducive to complete shielding design.The lead-steel composite material is applied to increase the strength and reduce the weight of the MRR.The optimized weight of the MRR is a-bout 271.9 kg.

  13. Monte-Carlo simulations of neutron shielding for the ATLAS forward region

    CERN Document Server

    Stekl, I; Kovalenko, V E; Vorobel, V; Leroy, C; Piquemal, F; Eschbach, R; Marquet, C


    The effectiveness of different types of neutron shielding for the ATLAS forward region has been studied by means of Monte-Carlo simulations and compared with the results of an experiment performed at the CERN PS. The simulation code is based on GEANT, FLUKA, MICAP and GAMLIB. GAMLIB is a new library including processes with gamma-rays produced in (n, gamma), (n, n'gamma) neutron reactions and is interfaced to the MICAP code. The effectiveness of different types of shielding against neutrons and gamma-rays, composed from different types of material, such as pure polyethylene, borated polyethylene, lithium-filled polyethylene, lead and iron, were compared. The results from Monte-Carlo simulations were compared to the results obtained from the experiment. The simulation results reproduce the experimental data well. This agreement supports the correctness of the simulation code used to describe the generation, spreading and absorption of neutrons (up to thermal energies) and gamma-rays in the shielding materials....

  14. Prediction of the shielding effectiveness at low frequency in near magnetic field (United States)

    Frikha, Amin; Bensetti, Mohamed; Duval, Fabrice; Lafon, Frédéric; Pichon, Lionel


    Equipment used in hybrid or electric vehicles (HEVs) must meet certain requirements. Beyond issues of electro-magnetic compatibility (EMC), it's necessary to assess the risks related to the exposure of the passengers to electromagnetic field inside an HEV. At low frequencies, using the electromagnetic shielding as protection is inefficient. The compliance can be achieved done by defining the harness's architecture or by the use of permeable materials. In this paper, we will focus on the prediction of the shielding effectiveness of materials subjected to a near magnetic field source at low frequency (9 kHz-10 MHz).We will focus our study on two cases. In the first case, we will work on the numerical modeling of an enclosure with and without opening. The result from the model is compared to the measurement's results obtained with a test bench developed in our laboratory. In the second case, the impact of the slot in the enclosure will be studied. An analytical method based on magnetic moments approximation is developed to predict the shielding effectiveness for infinite plane with slot. The results obtained with the latter are compared with the numerical results.

  15. Rapid Analysis of Mass Distribution of Radiation Shielding (United States)

    Zapp, Edward


    Radiation Shielding Evaluation Toolset (RADSET) is a computer program that rapidly calculates the spatial distribution of mass of an arbitrary structure for use in ray-tracing analysis of the radiation-shielding properties of the structure. RADSET was written to be used in conjunction with unmodified commercial computer-aided design (CAD) software that provides access to data on the structure and generates selected three-dimensional-appearing views of the structure. RADSET obtains raw geometric, material, and mass data on the structure from the CAD software. From these data, RADSET calculates the distribution(s) of the masses of specific materials about any user-specified point(s). The results of these mass-distribution calculations are imported back into the CAD computing environment, wherein the radiation-shielding calculations are performed.

  16. Optimal shielding thickness for galactic cosmic ray environments (United States)

    Slaba, Tony C.; Bahadori, Amir A.; Reddell, Brandon D.; Singleterry, Robert C.; Clowdsley, Martha S.; Blattnig, Steve R.


    Models have been extensively used in the past to evaluate and develop material optimization and shield design strategies for astronauts exposed to galactic cosmic rays (GCR) on long duration missions. A persistent conclusion from many of these studies was that passive shielding strategies are inefficient at reducing astronaut exposure levels and the mass required to significantly reduce the exposure is infeasible, given launch and associated cost constraints. An important assumption of this paradigm is that adding shielding mass does not substantially increase astronaut exposure levels. Recent studies with HZETRN have suggested, however, that dose equivalent values actually increase beyond ∼20 g/cm2 of aluminum shielding, primarily as a result of neutron build-up in the shielding geometry. In this work, various Monte Carlo (MC) codes and 3DHZETRN are evaluated in slab geometry to verify the existence of a local minimum in the dose equivalent versus aluminum thickness curve near 20 g/cm2. The same codes are also evaluated in polyethylene shielding, where no local minimum is observed, to provide a comparison between the two materials. Results are presented so that the physical interactions driving build-up in dose equivalent values can be easily observed and explained. Variation of transport model results for light ions (Z ≤ 2) and neutron-induced target fragments, which contribute significantly to dose equivalent for thick shielding, is also highlighted and indicates that significant uncertainties are still present in the models for some particles. The 3DHZETRN code is then further evaluated over a range of related slab geometries to draw closer connection to more realistic scenarios. Future work will examine these related geometries in more detail.

  17. Polymers Based on Renewable Raw Materials – Part I

    Directory of Open Access Journals (Sweden)


    Full Text Available This paper gives an overview of the production and application of polymer materials based on renewable raw materials – biopolymers. It is pointed out that, investment of resources in the study of renewable raw materials in the last twenty years has led to the improvement of old and development of completely new chemical and biochemical processes for using biomass for the production of low molecular weight chemical substances, and especially for the production of biopolymers, which are biodegradable and compostable, and biopolymers which are nonbiodegradable. In the same period, producers of polymers based on fossil raw materials have also developed biopolymers that are biodegradable and some of them compostable and, most important, compatible with biopolymers based on renewable raw materials. The facts considering the state of biopolymers based on renewable raw materials on the market, and prediction of production increase over the next five years are also stated. Additionally, the main renewable raw materials and the biopolymers made from them that are already present in the world market are briefly listed. A short review of biopolymers based on cellulose from wood and annual plants is also given.

  18. Boron-Based (Nano-Materials: Fundamentals and Applications

    Directory of Open Access Journals (Sweden)

    Umit B. Demirci


    Full Text Available The boron (Z = 5 element is unique. Boron-based (nano-materials are equally unique. Accordingly, the present special issue is dedicated to crystalline boron-based (nano-materials and gathers a series of nine review and research articles dealing with different boron-based compounds. Boranes, borohydrides, polyhedral boranes and carboranes, boronate anions/ligands, boron nitride (hexagonal structure, and elemental boron are considered. Importantly, large sections are dedicated to fundamentals, with a special focus on crystal structures. The application potentials are widely discussed on the basis of the materials’ physical and chemical properties. It stands out that crystalline boron-based (nano-materials have many technological opportunities in fields such as energy storage, gas sorption (depollution, medicine, and optical and electronic devices. The present special issue is further evidence of the wealth of boron science, especially in terms of crystalline (nano-materials.

  19. Overview of active methods for shielding spacecraft from energetic space radiation (United States)

    Townsend, L. W.; Wilson, J. W. (Principal Investigator)


    During the 1960's and into the early 1970's, investigations were conducted related to the feasibility of using active radiation shielding methods, such as afforded by electromagnetic fields, as alternatives to passive, bulk material shielding to attenuate space radiations. These active concepts fall into four categories: (1) electrostatic fields; (2) plasma shields; (3) confined magnetic fields; and (4) unconfined magnetic fields. In nearly all of these investigations, consideration was given only to shielding against protons or electrons, or both. During the 1980's and 1990's there were additional studies related to proton shielding and some new studies regarding the efficacy of using active methods to shield from the high energy heavy ion (HZE particle) component of the galactic cosmic ray spectrum. In this overview, each concept category is reviewed and its applicability and limitations for the various types of space radiations are described. Recommendations for future research on this topic are made.

  20. Vertical heterostructures based on graphene and other 2D materials

    Energy Technology Data Exchange (ETDEWEB)

    Antonova, I. V. [Rzhanov Institute of Semiconductor Physics, Russian Academy of Sciences, Siberian Branch (Russian Federation)


    Recent advances in the fabrication of vertical heterostructures based on graphene and other dielectric and semiconductor single-layer materials, including hexagonal boron nitride and transition-metal dichalcogenides, are reviewed. Significant progress in this field is discussed together with the great prospects for the development of vertical heterostructures for various applications, which are associated, first of all, with reconsideration of the physical principles of the design and operation of device structures based on graphene combined with other 2D materials.