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1

Preliminary earth berm shielding calculations for the accelerator production of tritium 1700-MeV accelerator  

SciTech Connect

The authors have performed calculations using the LAHET Code System (LCS) to obtain an estimation of the amount of earth berm shielding that will be required for the 1700-MeV proton accelerator proposed for the Accelerator Production of Tritium (APT) Project. A source scenario of 10 nA/m beam loss along the beam line was used to calculate the dose values above a 6-m earth berm from high-energy neutrons, low-energy neutrons, and photons. LAHET, a Monte Carlo based particle transport code, was used to transport a 1700-MeV protons from the beam along a divergence path of 1{degree} from the original beam direction and impacting representative beampipe material along a 300-m beamline. LAHET was then used to track all high-energy neutron production until the neutrons either escape the berm shield, or scatter down in energy to 20 MeV, where their parameters were then written to a source file for MCNP. Photon production data was also written to a source file used by MCNP. MCNP transported all neutrons and photons from the LAHET source file until they (1) were absorbed, scattered down to an energy cutoff, or (2) escaped from the system. Doses were calculated from surface flux tallies obtained from LAHET and MCNP. These doses were then compared to earlier Moyer model calculations.

Court, J.D.; Pitcher, E.J.; Ferguson, P.D.; Russell, G.J.; Patton, B.W.

1998-07-01

2

SOUTHWEST REAR AND SOUTHEAST SIDE. Protective berm at left shields ...  

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

SOUTHWEST REAR AND SOUTHEAST SIDE. Protective berm at left shields Air Supply building from launch pad - Edwards Air Force Base, South Base Sled Track, Air Supply Building for Building No. 0545, South of Sled Track at east end, Lancaster, Los Angeles County, CA

3

Quantity-Distance Requirements for Earth-Bermed Aircraft Shelters.  

National Technical Information Service (NTIS)

The subject work has been performed under Phase I of an SBIR (small business innovative research) program sponsored by Tyndall AFB. The effort concentrated on development of methods to quantify debris hazards from accidental explosions inside earth-bermed...

M. G. Whitney K. H. Spivey

1993-01-01

4

Digital Simulation Analysis for Evaluating Earth Berm Design and Vehicle Dynamics.  

National Technical Information Service (NTIS)

This study deals with the evaluation and modification of the original North Carolina earth berm based on the generalized vehicle dynamic analysis and computer-aided design using digital simulation techniques. Simulation runs of vehicle-berm interaction we...

B. K. Huang K. H. Kim

1975-01-01

5

Jupiter: Earth's Shield  

NSDL National Science Digital Library

More than 155 planets have been found outside of our solar system since the first extra-solar planet was identified in 1995. The search has long been heavily biased towards finding massive planets with short orbits. Now, to find an Earth-like planet, scientists are looking for a planetary setup that is similar to our own, in which a Jupiter-like planet lies a good distance away from its sun. This video segment adapted from NOVA explores how the arrangement of planets in our solar system may have affected the development of life on Earth.

Foundation, Wgbh E.

2009-07-13

6

Jupiter: Earth's Shield  

NSDL National Science Digital Library

More than 155 planets have been found outside of our solar system since the first discovery in 1995, mostly massive Jupiter-like planets in orbits close to their suns. Now, to find an Earth-like planet, scientists are looking for a planetary setup that is similar to our own, in which a Jupiter-like planet lies a good distance away from its sun. This video segment explores how the arrangement of planets in our solar system may have affected the development of life on Earth and describes how researchers are searching for the right planetary setup. The segment is two minutes one second in length. A background essay and list of discussion questions are also provided.

7

Earth pressure balance control for EPB shield  

Microsoft Academic Search

This paper mainly deals with the critical technology of earth pressure balance (EPB) control in shield tunneling. On the assumption\\u000a that the conditioned soil in the working chamber of the shield is plasticized, a theoretical principle for EPB control is\\u000a proposed. Dynamic equilibrium of intake volume and discharge volume generated by thrust and discharge is modeled theoretically\\u000a to simulate the

HuaYong Yang; Hu Shi; GuoFang Gong; GuoLiang Hu

2009-01-01

8

Shielding and Crystal Fields at Rare-Earth Ions  

Microsoft Academic Search

Several aspects of the crystal field problem of rare-earth ions in ionic solids are discussed. In particular, three problems are considered. (1) A calculation is performed to determine to what extent the 5s2p6 electrons shield the 4f electrons from the crystal field. The shielding is small (<10%) and unimportant compared to the many other uncertainties in crystal field calculations. The

Gerald Burns

1962-01-01

9

Reconnection: Solar Wind Breaches the Earths Magnetic Shield  

NSDL National Science Digital Library

The Far Ultraviolet camera abord the IMAGE spacecraft captured this view of a proton aurora (the bright spot near the center of the view) as well as the ring of the electron aurora. The protons for this aurora came from the incoming solar wind. The made it though the Earths magnetic shield in a magnetic reconnection event higher in the magnetosphere which was detected by the Cluster satellite. Note: A corner appears in the data in the beginning as the IMAGE spacecraft moves into a position where it can view the entire north polar region.

Bridgman, Tom; Frey, Harald; Phan, Tai

2003-12-04

10

Numerical Simulation of Earth Pressure on Head Chamber of Shield Machine with FEM  

NASA Astrophysics Data System (ADS)

Model parameters of conditioned soils in head chamber of shield machine are determined based on tree-axial compression tests in laboratory. The loads acting on tunneling face are estimated according to static earth pressure principle. Based on Duncan-Chang nonlinear elastic constitutive model, the earth pressures on head chamber of shield machine are simulated in different aperture ratio cases for rotating cutterhead of shield machine. Relationship between pressure transportation factor and aperture ratio of shield machine is proposed by using aggression analysis.

Li, Shouju; Kang, Chengang; Sun, Wei; Shangguan, Zichang

2010-05-01

11

Numerical Simulation of Earth Pressure on Head Chamber of Shield Machine with FEM  

SciTech Connect

Model parameters of conditioned soils in head chamber of shield machine are determined based on tree-axial compression tests in laboratory. The loads acting on tunneling face are estimated according to static earth pressure principle. Based on Duncan-Chang nonlinear elastic constitutive model, the earth pressures on head chamber of shield machine are simulated in different aperture ratio cases for rotating cutterhead of shield machine. Relationship between pressure transportation factor and aperture ratio of shield machine is proposed by using aggression analysis.

Li Shouju; Kang Chengang [State Key Laboratory of structural analysis for industrial equipment, Dalian University of Technology, Dalian 116023 (China); Sun, Wei [School of Mechanical Engineering, Dalian University of Technology, Dalian 116023 (China); Shangguan Zichang [School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 116023 (China); Institute of Civil Engineering, Dalian Fishery University, Dalian 116023 (China)

2010-05-21

12

Electronic shielding of the crystalline electric field in rare earth ions  

Microsoft Academic Search

The effect of electronic shielding on the A20 term of the crystal field potential of the Pr3+ and the Tm3+ ion has been estimated from the numerical solution of the first-order perturbation equation. The shielding factor ?2 is 0.59 and 0.70 for Tm3+ and Pr3+ respectively. The results stress the importance of electronic shieldings in rare-earth ions in agreement with

M. N. Ghatikar; A. K. Raychaudhuri; D. K. Ray

1965-01-01

13

Electronic shielding of the crystalline electric field in rare earth ions  

Microsoft Academic Search

The effect of electronic shielding on the A20 term of the crystal field potential of the Pr3+ and the Tm3+ ion has been estimated from the numerical solution of the first-order perturbation equation. The shielding factor sigma2 is 0.59 and 0.70 for Tm3+ and Pr3+ respectively. The results stress the importance of electronic shieldings in rare-earth ions in agreement with

M. N. Ghatikar; A. K. Raychaudhuri; D. K. Ray

1965-01-01

14

SPERTI Reactor Pit Building (PER605). Earth shielding protect adjacent Instrument ...  

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

SPERT-I Reactor Pit Building (PER-605). Earth shielding protect adjacent Instrument Cell (PER-606). Security fencing surrounds complex, to which gate entry is provided next to Guard House (PER-607). Note gravel road leading to control area. Earth-covered conduit leads from instrument cell to terminal building out of view. Photographer: R.G. Larsen. Date: June 22, 1955. INEEL negative no. 55-1701 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

15

FET. Control and equipment building (TAN630). Sections. Earth cover. Shielded ...  

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

FET. Control and equipment building (TAN-630). Sections. Earth cover. Shielded access entries for personnel and vehicles. Ralph M. Parsons 1229-2 ANP/GE-5-630-A-3. Date: March 1957. Approved by INEEL Classification Office for public release. INEEL index code no. 036-0630-00-693-107082 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

16

Using the EXIST Active Shields for Earth Occultation Observations of X-ray Sources  

Microsoft Academic Search

The EXIST active shields, now being planned for the main detectors of the coded aperture telescope, will have approximately 15 times the area of the BATSE detectors; and they will have a good geometry on the spacecraft for viewing both the leading and trailing Earth's limb for occultation observations. These occultation observations will complement the imaging observations of EXIST and

C. A. Wilson; G. J. Fishman; J. Hong; J. Grindlay; H. Krawczynski

2004-01-01

17

Using the EXIST Active Shields for Earth Occultation Observations of X-ray Sources  

Microsoft Academic Search

The EXIST active shields, planned for the main detectors of the coded aperture telescope, will have approximately 15 times the area of the BATSE detectors, and they will have a good geometry on the spacecraft for viewing both the leading and trailing Earth's limb for occultation observations. These occultation observations will complement the imaging observations of EXIST and can extend

Colleen A. Wilson; G. J. Fishman; J.-S. Hong; J. E. Grindlay; H. Krawczynski

2005-01-01

18

2. CONCRETE PADDING AREA BETWEEN BERM MOUNDS, LOOKING NORTH FROM ...  

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

2. CONCRETE PADDING AREA BETWEEN BERM MOUNDS, LOOKING NORTH FROM TOP OF BERM. - NIKE Missile Base C-84, Acid Fueling Station, North of Launch Area Entrance Drive, eastern central portion of base, Barrington, Cook County, IL

19

Beach face and berm morphodynamics fronting a coastal lagoon  

Microsoft Academic Search

This study documents two different modes of berm development: (1) vertical growth at spring tides or following significant beach cut due to substantial swash overtopping, and (2) horizontal progradation at neap tides through the formation of a proto-berm located lower and further seaward of the principal berm. Concurrent high-frequency measurements of bed elevation and the associated wave runup distribution reveal

Felicia M. Weir; Michael G. Hughes; Tom E. Baldock

2006-01-01

20

The Highest Cosmic Ray Fluxes Ever Recorded: What Happened to the Earth's Deflector Shield?  

NASA Astrophysics Data System (ADS)

The summer of 2009 saw the largest cosmic ray flux ever measured at Earth. Cosmic ray intensities in the 270-450 MeV/nucleon range were nearly 20% larger than anything previously recorded. Clearly, something dramatically affected the cosmic ray 'deflector shield' of the Earth during the most recent solar activity minimum. We explore the cause of this marked increase by examining properties of the global solar magnetic field and conditions in the solar wind during the previous solar minimum and compare these to previous solar cycles using in-situ and remote sensing observations.

Burkepile, J.; McIntosh, S. W.; Gurman, J. B.; Leamon, R. J.

2010-12-01

21

Experimental study on working parameters of earth pressure balance shield machine tunneling in soft ground  

Microsoft Academic Search

Deep sedimentary deposits of soft clays are widely distributed in coastal areas as well as many interior major cities in China.\\u000a In order to study the stratum adaptability of earth pressure balance (EPB) shield machine tunneling in such types of soft\\u000a ground, model tests of tunneling excavation, using the running tunnel of the Shanghai Metro Line M8 as a background,

Hehua Zhu; Qianwei Xu; Qizhen Zheng; Shaoming Liao

2008-01-01

22

Deep reflection seismography in studying the Earth's crust of the Ukrainian Shield  

Microsoft Academic Search

The results of studies of the Ukrainian Shield (USh) basic structures (Sura sinclinorium, Korsun'-Novomirgorod pluton, Krivoy Rog structure, Novoukrainka massif, Central and Southern USh) by the seismic reflected CDP-method are considered and analysed. The structures given show high effectivity of the seismic reflected CDP-method in studying USh Earth's crust structure. The wave field is dominated by single reflections and their

A. V. Chekunov; A. A. Tripolsky; O. M. Kharitonov

1997-01-01

23

Using the EXIST Active Shields for Earth Occultation Observations of X-ray Sources  

Microsoft Academic Search

The EXIST active shields, planned for the main detectors of the coded\\u000aaperture telescope, will have approximately 15 times the area of the BATSE\\u000adetectors, and they will have a good geometry on the spacecraft for viewing\\u000aboth the leading and trailing Earth's limb for occultation observations. These\\u000aoccultation observations will complement the imaging observations of EXIST and\\u000acan extend

Colleen A. Wilson; G. J. Fishman; J.-S. Hong; J. E. Grindlay; H. Krawczynski

2005-01-01

24

a Fractal Aggregate Model of Early Earth Organic Hazes: UV Shielding with Minimal Antigreenhouse Cooling  

NASA Astrophysics Data System (ADS)

The Archean Earth (3.8 to 2.5 billion years ago) was probably enshrouded by a Titan-like photochemical haze composed of fractal aggregate hydrocarbon aerosols. In this study a three-dimensional fractal aggregate model of the early Earth photochemical haze is explored and compared with the standard liquid drop haze model used in earlier studies. Fractal aggregate microphysical processes are modeled using the method introduced by Cabane et al. [Planet. Space Sci. 41, 257, 1993]. The optical properties of the aerosols are determined using a mean-field approximation of multiple scattering by fractal aggregates composed of identical spheres [Botet at al. Earth fractal hazes are found to be optically thick in the ultraviolet wavelengths while remaining relatively transparent in the mid-visible wavelengths. At an annual production rate of 1014 grams per year and an average monomer radius of 50 nanometers, the haze has global mean effective optical depths of ?uv = 11.2 and ?vis = 0.5. Such a haze would provide a strong shield against UV light while causing only minimal antigreenhouse cooling. Protected by a strong UV shield, photolytically unstable greenhouse gases such as CH4 and NH3 may have been able to build up to high concentrations helping warm the young Earth despite the faint young Sun. Our findings reopen the hypothesis of Sagan and Mullen [Science 177, 52, 1972] that the young Earth may have been home to a reducing atmosphere.

Wolf, E. T.; Toon, O. B.

2010-12-01

25

Evidence for the Snowball Earth hypothesis in the Arabian-Nubian Shield and the East African Orogen  

Microsoft Academic Search

Formation of the Arabian-Nubian Shield (ANS) and the East African Orogen (EAO) occurred between 870Ma and the end of the Precambrian (?542Ma). ANS crustal growth encompassed a time of dramatic climatic change, articulated as the Snowball Earth hypothesis (SEH). SEH identifies tremendous paleoclimatic oscillations during Neoproterozoic time. Earth’s climate shifted wildly, from times when much of our planet’s surface was

R. J. Stern; D. Avigad; N. R. Miller; M. Beyth

2006-01-01

26

Using the EXIST Active Shields for Earth Occultation Observations of X-ray Sources  

NASA Astrophysics Data System (ADS)

The EXIST active shields, planned for the main detectors of the coded aperture telescope, will have approximately 15 times the area of the BATSE detectors, and they will have a good geometry on the spacecraft for viewing both the leading and trailing Earth's limb for occultation observations. These occultation observations will complement the imaging observations of EXIST and can extend them to higher energies. Earth occultation observations of the hard X-ray sky with BATSE on the Compton Gamma Ray Observatory developed and demonstrated the capabilities of large, at, uncollimated detectors for applying this observation method. With BATSE, a catalog of 179 X-ray sources was monitored twice every spacecraft orbit for 9 years at energies above about 25 keV, resulting in 83 definite detections and 36 possible detections with 5 ? detection sensitivities of 3.5-20 mcrab (20-430 keV) depending on the sky location. This catalog included four transients discovered with this technique and many variable objects (galactic and extragalactic.) This poster describes the Earth occultation technique, summarizes the BATSE occultation observations, and compares the basic observational parameters of the occultation detector elements of BATSE and EXIST.

Wilson, Colleen A.; Fishman, G. J.; Hong, J.-S.; Grindlay, J. E.; Krawczynski, H.

27

Using the EXIST Active Shields for Earth Occultation Observations of X-ray Sources  

NASA Astrophysics Data System (ADS)

The EXIST active shields, now being planned for the main detectors of the coded aperture telescope, will have approximately 15 times the area of the BATSE detectors; and they will have a good geometry on the spacecraft for viewing both the leading and trailing Earth's limb for occultation observations. These occultation observations will complement the imaging observations of EXIST and can extend them to higher energies. Earth occultation observations of the hard X-ray sky with BATSE on the Compton Gamma Ray Observatory developed and demonstrated the capabilities of large, flat, uncollimated detectors for this method. With BATSE, a catalog of 179 X-ray sources was monitored twice every spacecraft orbit for 9 years at energies above about 25 keV, resulting in 83 definite detections and 36 possible detections with 5-? detection sensitivities of 3.5-20 mcrab (20-430 keV) depending on the sky location. This catalog included four transients discovered with this technique and many variable objects (galactic and extragalactic.) This poster will describe the Earth occultation technique, summarize the BATSE occultation observations, and compare the basic observational parameters of the occultation detector elements of BATSE and EXIST.

Wilson, C. A.; Fishman, G. J.; Hong, J.; Grindlay, J.; Krawczynski, H.

2004-12-01

28

Aerothermodynamic optimization of Earth entry blunt body heat shields for Lunar and Mars return  

NASA Astrophysics Data System (ADS)

A differential evolutionary algorithm has been executed to optimize the hypersonic aerodynamic and stagnation-point heat transfer performance of Earth entry heat shields for Lunar and Mars return manned missions with entry velocities of 11 and 12.5 km/s respectively. The aerothermodynamic performance of heat shield geometries with lift-to-drag ratios up to 1.0 is studied. Each considered heat shield geometry is composed of an axial profile tailored to fit a base cross section. Axial profiles consist of spherical segments, spherically blunted cones, and power laws. Heat shield cross sections include oblate and prolate ellipses, rounded-edge parallelograms, and blendings of the two. Aerothermodynamic models are based on modified Newtonian impact theory with semi-empirical correlations for convection and radiation. Multi-objective function optimization is performed to determine optimal trade-offs between performance parameters. Objective functions consist of minimizing heat load and heat flux and maximizing down range and cross range. Results indicate that skipping trajectories allow for vehicles with L/D = 0.3, 0.5, and 1.0 at lunar return flight conditions to produce maximum cross ranges of 950, 1500, and 3000 km respectively before Qs,tot increases dramatically. Maximum cross range increases by ˜20% with an increase in entry velocity from 11 to 12.5 km/s. Optimal configurations for all three lift-to-drag ratios produce down ranges up to approximately 26,000 km for both lunar and Mars return. Assuming a 10,000 kg mass and L/D = 0.27, the current Orion configuration is projected to experience a heat load of approximately 68 kJ/cm2 for Mars return flight conditions. For both L/D = 0.3 and 0.5, a 30% increase in entry vehicle mass from 10,000 kg produces a 20-30% increase in Qs,tot. For a given L/D, highly-eccentric heat shields do not produce greater cross range or down range. With a 5 g deceleration limit and L/D = 0.3, a highly oblate cross section with an eccentricity of 0.968 produces a 35% reduction in heat load over designs with zero eccentricity due to the eccentric heat shield's greater drag area that allows the vehicle to decelerate higher in the atmosphere. In this case, the heat shield's drag area is traded off with volumetric efficiency while fulfilling the given set of mission requirements. Additionally, the high radius-of-curvature of the spherical segment axial profile provides the best combination of heat transfer and aerodynamic performance for both entry velocities and a 5 g deceleration limit.

Johnson, Joshua E.

29

The highest cosmic ray fluxes ever recorded: What happened to the earth's deflector shield?  

NASA Astrophysics Data System (ADS)

The summer of 2009 saw the largest cosmic ray flux ever measured at 1AU. Observed by neutron monitors this solar minimum flux was 6% larger than that of the last solar minimum in 1996, and 4% larger than the previous high of the space age. Clearly, something dramatically affected the cosmic ray "deflector shield" of the Earth this time around, but what was it? Using a combination of serendipitous observations made by the solid state recorder of the SOHO spacecraft, an analysis of SOHO/MDI magnetograms combined with SOHO/EIT and SDO/AIA coronal imaging, we deduce that a pronounced north-south asymmetry in the meridional circulation flow resulted in the evolution of the photospheric magnetic to a prolonged prevalence of the negative magnetic polarity in the equatorial region that were the root cause of the observed cosmic ray flux increase. The negative sign, weakness and low rigidity of the interplanetary magnetic field, driven by the excess of open magnetic flux resulting from the flow asymmetry in the solar interior, enabled more cosmic rays of the energy range measured at Earth to creep into our atmosphere than previously measured.

Leamon, R. J.; Mcintosh, S. W.; Burkepile, J.; Sitongia, L.; Markel, R. S.; Gurman, J. B.; Olive, J.

2011-12-01

30

24. GENERAL VIEW OF NEW CONCRETE BLAST BERM FOR NEW ...  

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

24. GENERAL VIEW OF NEW CONCRETE BLAST BERM FOR NEW LIQUID HYDROGEN TANK FARM; VIEW TO EAST. - Cape Canaveral Air Station, Launch Complex 17, Facility 28402, East end of Lighthouse Road, Cape Canaveral, Brevard County, FL

31

3. Earthen berm and water control structure used to regulate ...  

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

3. Earthen berm and water control structure used to regulate water flow into adjacent cultivated area - Natomas Ditch System, Blue Ravine Segment, Juncture of Blue Ravine & Green Valley Roads, Folsom, Sacramento County, CA

32

17. View from Sterling Creek Marsh looking west, with berm ...  

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

17. View from Sterling Creek Marsh looking west, with berm to the left and Henry Ford Mansion in the far background - Richmond Hill Plantation, Sterling Creek Marsh, East of Richmond Hill on Ford Neck Road, Richmond Hill, Bryan County, GA

33

8. Water treatment plant, view to SE, berm in foreground ...  

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

8. Water treatment plant, view to SE, berm in foreground covering settling tank - Fort Benton Water Treatment Plant, Filtration Plant, Lots 9-13 of Block 7, Fort Benton Original Townsite at Missouri River, Fort Benton, Chouteau County, MT

34

4. Water treatment plant, view to NW, berm in foreground ...  

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

4. Water treatment plant, view to NW, berm in foreground - Fort Benton Water Treatment Plant, Filtration Plant, Lots 9-13 of Block 7, Fort Benton Original Townsite at Missouri River, Fort Benton, Chouteau County, MT

35

7. Water treatment plant, view to E, berm in foreground ...  

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

7. Water treatment plant, view to E, berm in foreground covering settling tank - Fort Benton Water Treatment Plant, Filtration Plant, Lots 9-13 of Block 7, Fort Benton Original Townsite at Missouri River, Fort Benton, Chouteau County, MT

36

6. Water treatment plant, view NE, berm in foreground ...  

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

6. Water treatment plant, view NE, berm in foreground - Fort Benton Water Treatment Plant, Filtration Plant, Lots 9-13 of Block 7, Fort Benton Original Townsite at Missouri River, Fort Benton, Chouteau County, MT

37

5. Water treatment plant, view to N, berm in foreground ...  

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

5. Water treatment plant, view to N, berm in foreground - Fort Benton Water Treatment Plant, Filtration Plant, Lots 9-13 of Block 7, Fort Benton Original Townsite at Missouri River, Fort Benton, Chouteau County, MT

38

3. CONCRETE FORMATIONS IN LOWER AREA BETWEEN BERMS, LOOKING SOUTHEAST. ...  

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

3. CONCRETE FORMATIONS IN LOWER AREA BETWEEN BERMS, LOOKING SOUTHEAST. - NIKE Missile Base C-84, Acid Fueling Station, North of Launch Area Entrance Drive, eastern central portion of base, Barrington, Cook County, IL

39

1. BERMED AREA, LOOKING FROM SILO 'O' POSITION, NORTHWEST. ...  

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

1. BERMED AREA, LOOKING FROM SILO 'O' POSITION, NORTHWEST. - NIKE Missile Base C-84, Acid Fueling Station, North of Launch Area Entrance Drive, eastern central portion of base, Barrington, Cook County, IL

40

Seasonal Berm Behavior on a Coastal Lagoon Pocket Beach  

NASA Astrophysics Data System (ADS)

Coastal lagoon beaches are typically characterized by a seasonal berm that separates the lagoon mouth from the open ocean during summer months and is temporarily breached and eroded offshore as a result of higher wave energy during winter months. Seasonal morphodynamic changes on a coastal lagoon pocket beach in Santa Cruz, California were monitored from August 2010 to April 2011. Monthly total station GPS surveys were conducted on Younger Lagoon Reserve beach in conjunction with monthly grain size analyses. A time series comparison of beach profiles extracted from shore-normal transects reveals that the berm fronting the lagoon mouth did not erode with increasing wave energy during the winter months as expected, but either stayed fixed while the foreshore steepened or migrated horizontally across shore. Berm height is likely maintained by wave overtopping of the berm crest at the lagoon mouth during high tides or storm events. Foreshore steepening occurs in conjunction with an increase in coarse sediment fraction and is consistent with increasing wave energy and turbulent swash interaction. Cross-shore sediment transport in the foreshore fronting the lagoon mouth is likely enhanced by infiltration and exfiltration of water on the shoreface due to the position of the water table with respect to the maximum swash runup. Coastal lagoon beach berm behavior and the subsequent extent of lagoon-ocean mixing has important implications for coastal water quality and lagoon ecosystem dynamics.

Harden, L.

2011-12-01

41

Design and analyse space radiation shielding for a Nanosatellite in low earth orbit (LEO)  

Microsoft Academic Search

In this paper we design and analyze space radiation shielding for Nanosatellite with perigee 250 km and apogee 650 km, with endurance one month in solar max activity. At first step space radiation environment simulated. The proton spectrum energy in inner Van Allen belt varies from 0.01 MeV to 400 MeV. In second step radiation shield designed. The shield was

Masood Mayanbari; Yaser Kasesaz

2011-01-01

42

Canmar's berm-supported SSDC drilling advances arctic technology  

SciTech Connect

This report describes design, installation and performance of the single steel drilling caisson (SSDC) on a subsea berm. It details key points learned from the $100-million project by Canadian Marine Drilling Ltd. installed in the Beaufort Sea. Unitized construction allows for permanent installation and hookup of the drilling rig package. Mobilization and demobilization is much simpler, resulting in quicker and safer operation than that required with a multi-caisson system. The high freeboard achieved with the SSDC unit gives much greater protection with respect to wave run-up and ice ride-up, resulting in significant operational improvements. The relatively low elevation of the submerged berm at 9 m below sea level results in improved berm stability and erosion resistance.

Hewitt, K.J.; Berzins, W.E.; Fitzpatrick, J.P.; Hogeboom, H.G.

1985-07-01

43

3. GENERAL VIEW ACROSS CANAL PRISM TO TOWPATH BERM NORTH ...  

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

3. GENERAL VIEW ACROSS CANAL PRISM TO TOWPATH BERM NORTH OF THE SPILLWAY; VIEW TO WEST FROM ROUTE 146 EMBANKMENT. - Blackstone Canal Millbury Segment, Beginning northwest of State Route 146 & McCracken Road, running along west side of Route 146, Millbury, Worcester County, MA

44

1. GENERAL VIEW, TOWPATH BERM (CENTER) AND CANAL PRISM (LEFT) ...  

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

1. GENERAL VIEW, TOWPATH BERM (CENTER) AND CANAL PRISM (LEFT) SOUTH OF THE SPILLWAY; VIEW TO SOUTH. - Blackstone Canal Millbury Segment, Beginning northwest of State Route 146 & McCracken Road, running along west side of Route 146, Millbury, Worcester County, MA

45

NORTHERLY STRETCH OF MILLBURY PORTION, GENERAL VIEW SHOWING TOWPATH BERM ...  

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

NORTHERLY STRETCH OF MILLBURY PORTION, GENERAL VIEW SHOWING TOWPATH BERM (CENTER/RIGHT) AND CANAL PRISM (LEFT); VIEW TO SOUTH FROM FOOT OF THE "TOWN-LINE DUMP" - Blackstone Canal Worcester-Millbury Segment, Eastern bank of Blackstone River, Millbury, Worcester County, MA

46

SOUTHERLY STRETCH OF MILLBURY PORTION; GENERAL VIEW OF TOWPATH BERM ...  

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

SOUTHERLY STRETCH OF MILLBURY PORTION; GENERAL VIEW OF TOWPATH BERM (LEFT) AND CANAL PRISM (CENTER) WITH LATER EMBANKMENT OF U.S. ROUTE 20 RAMP ENCROACHING RIGHT; VIEW TO NORTH - Blackstone Canal Worcester-Millbury Segment, Eastern bank of Blackstone River, Millbury, Worcester County, MA

47

2. GENERAL VIEW ACROSS CANAL PRISM TO TOWPATH BERM SOUTH ...  

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

2. GENERAL VIEW ACROSS CANAL PRISM TO TOWPATH BERM SOUTH OF THE SPILLWAY; VIEW TO SOUTHWEST FROM ROUTE 146 EMBANKMENT. - Blackstone Canal Millbury Segment, Beginning northwest of State Route 146 & McCracken Road, running along west side of Route 146, Millbury, Worcester County, MA

48

UPSTREAM (WEST) VIEW SHOWING SOUTH EMBANKMENT BERM AND CONCRETE COREWALL ...  

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

UPSTREAM (WEST) VIEW SHOWING SOUTH EMBANKMENT BERM AND CONCRETE COREWALL AT CENTER, WITH COOKE DAM POND AT LEFT AND POWERHOUSE (MI-98-C) AND SPILLWAY (MI-98-B) IN BACKGROUND. VIEW TO NORTHEAST - Cooke Hydroelectric Plant, South Embankment, Cook Dam Road at Au Sable River, Oscoda, Iosco County, MI

49

Thermo-chemical ablation of heat shields under Earth reentry conditions  

NASA Astrophysics Data System (ADS)

The process of ablation for earth atmospheric entry is modeled. The flowfield surrounding the ablator is modeled by an extended set of Navier-Stokes equations that include the effects of thermochemical nonequilibrium. This set of equations encompasses the conservation of mass for each chemical species, conservation of momentum, the conservation of vibrational energy, and the conservation of total energy. The heat conduction into the ablator material is modeled by using Fourier's Law of heat conduction and the heat equation. The flowfield and ablator are coupled by a thermochemical ablation model that includes a surface mass balance and a surface energy balance. The ablation model takes into account chemical reactions of the flowfield species with the surface material, surface material acting as a catalytic surface, and sublimation of the surface material. To solve the governing equations for the model, a computational fluid dynamics approach is used where the flowfield is solved using a modified Steger-Warming flux vector splitting scheme and the solid is solved using a centrally differenced scheme. A Gauss-Seidel line relaxation technique is implemented to speed numerical convergence. The flowfield model is verified by comparing to flowfield computations of other researchers and to experimental data. The ablator/heat shield model is validated by a direct comparison between an exact analytical solution and a numerical solution. The thermochemical ablation model is verified by comparing to the experimental results of the Passive Nosetip Technology (PANT) program. The model is used to calculate steady-state ablation data for sphere-cone reentry bodies. Two bodies with nose radii of 0.0127 m and 0.1270 m are tested at a velocity of 8 km/s. The ablator material is selected to be a commercial grade graphite. Due to the ablator selection, the flowfield is limited to 11 chemical species and two internal energy modes. A standard earth atmosphere is selected at altitudes ranging from 40 km to 80 km. The major results concern the thermochemical ablation model. Both oxidation and sublimation mechanisms are evident and are dependent on freestream conditions and the reentry body shape.

Keenan, James Anthony

1994-04-01

50

How to protect the Earth from Global warming by means of Sunlight Shield Equipments  

Microsoft Academic Search

The Earth is getting warmer because excess carbon dioxide of the Earth's atmosphere. Many studies are proceeding in the world in order to prevent global warming. Three methods are studied: (1) How to reduce carbon dioxide of the Earth's atmosphere. For example, more trees will be planted and carbon dioxide is changed to oxygen and carbon. (2) How to reduce

H. Murakami

2010-01-01

51

Water Quality Characteristics and Performance of Compost Filter Berms, Summary Report.  

National Technical Information Service (NTIS)

Several recent Texas Department of Transportation (TxDOT) pilot efforts demonstrated the beneficial uses of compost in roadside applications. Specific uses of composted materials on the roadside include erosion control, compost filter berms, and compost f...

A. B. Raut Desai B. B. Storey H. C. Landphair M. H. Li

2006-01-01

52

Computer simulation of heat transfer from earth sheltered structures: A comparison of varying levels of earth sheltering in five different climates  

Microsoft Academic Search

Computer predictions of the HVAC energy consumption for single story office buildings with varying levels of earth-sheltering indicate that significant energy savings are possible with fully-bermed and bermed-and-covered configurations. As shown by the computer analysis, increased earth-sheltering reduced uncontrolled infiltration; improved the thermal performance of the walls, roof, and floor; and located the windows for more favorable passive solar gain.

Meixel

1980-01-01

53

Nitrogen and phosphorus transport in runoff from compost berms on a simulated military training landscape.  

PubMed

Compost mulches have potential to significantly offset on- and off-site environmental impacts resulting from mechanical soil disturbances and training manoeuvres on military training ranges. N and P transport was investigated in runoff from compost mulch berms made from various organic waste materials in combination with each other and with soil on a simulated military training landscape in north Alabama in 2007 and 2008. Berms were constructed using composted municipal yard waste (YW), wood chips (WC), pine bark fines (PB), and soil (SL) mixed in eight different proportions. Berms made from 100% soil which had a cumulative runoff PO(4)-P content of 12 mg L(-1) posed the greatest threat of negatively impacting the environment from inorganic P transport. Using compost mulch material with 40% soil to build berms reduced the potential for yard waste and wood chips to cause off-site negative environmental impacts from total dissolved solids, N, and P transport. Berms made from 100% pine bark fines which had cumulative runoff values of 760, 9, 22 and 5 mg L( -1), respectively, of TDS, NH(4)-N, NO(3)-N, and PO( 4)-P had the least potential to cause negative off-site environmental impact. To prevent negative impacts of nutrient transport in runoff from berms on training landscapes, the sites need to be well buffered to hydrologically isolate them from adjoining ecosystems. PMID:20406749

Nyakatawa, Ermson Z; Mays, David A; Britton, Rhonda; Pacumbaba, Rudolfo O; Howard, H R; Svendsen, N G

2010-04-20

54

Progress Toward Electrostatic Radiation Shielding of Interplanetary Spacecraft: Strategies, Concepts and Technical Challenges of Human Exploration Beyond Low Earth Orbit.  

National Technical Information Service (NTIS)

The radiation problem is a serious obstacle to solar system exploration. Electrostatic shielding was previously dismissed as unworkable. This was based on the false assumption that radial symmetry is needed to provide isotropic protection. KSC recently de...

J. E. Lane P. T. Metzger R. C. Youngquist

2004-01-01

55

Shielding Strategies for Human Space Exploration  

Microsoft Academic Search

The shield effectiveness of lunar regolith is compared with possible prefabricated shield materials from Earth,including commercially used shield materials in nuclear facilities. Several of the fabricated materials categorized asneutron absorbers and moderators exhibit favorable characteristics for space radiation protection. Although thiseffort is not intended to be a definitive trade study for specific shielding recommendations, attention is given toseveral factors that

J. W. Wilson; J. Miller; A. Konradi; F. A. Cucinotta

1997-01-01

56

Novel preorganized hemispherands to encapsulate rare earth ions: shielding and ligand deuteration for prolonged lifetimes of excited Eu3+ ions  

Microsoft Academic Search

Quenching of the luminescent excited state of Eu3+ ions by C-H high-vibrational modes was studied by deuteration of the encapsulating ligand and the solvent. Novel polydentate hemispherands providing nine donor atoms, which form overall neutral complexes with rare earth ions, were synthesized in nine steps, allowing the easy incorporation of deuterium atoms (11a-d·Eu3+). The introduction of tert-butyl groups at the

Manon P. Oude Wolbers; Veggel van Frank C. J. M; Bianca H. M. Snellink-Ruel; Johannes W. Hofstraat; Frank A. J. Geurts; David N. Reinhoudt

1997-01-01

57

Effect of diatomaceous earths Fossil Shield and Silico-Sec on the egg laying behaviour of Callosobruchus maculatus (F.) (Coleoptera: Bruchidae).  

PubMed

The pulse beetle, Callosobruchus maculatus (F.) is a destructive pest of pulses in both storage and field. It is well known that diatomaceous earth (DE) kill the insects by locally absorbing the epicuticular lipid layers leading to high rate of water loss through the cuticle. However, the effectiveness of DE depends on its ability to kill the adults before copulation and egg-laying. Newly emerged virgin males and females of Callosobruchus maculatus (F.) were exposed to the DEs, Fossil-Shield and Silico-Sec on 30 treated mungbeans (Vigna radita (L)). Fecundity, number of beans used for egg-laying and beans without eggs were evaluated after four days; the number of unhatched eggs was evaluated after ten days. It was determined, that the fecundity of female insects decreased sigmoidely with increasing rate of DE content. Percentages of unhatched eggs and seeds without eggs increased with increasing DE dosages. However, the maximum egg densities (eggs per used secd) occurred at 1200 mg DE/kg for Fossil-Shield and Silico-Sec. The reason for such DE-stimulated behaviour of egg laying expressed as a number of seeds with eggs of C. maculatus is not known, but it may be related to the stress caused by the inert dusts or to the reduction of both chemical and physical (tactile) stimuli. Treatment with DEs altered the surface texture of the beans and caused less cohesion between eggs and the seed surface. Only few larvae managed to penetrate into the grains, possibly due to increased grain roughness and repellent effect of DE. A relatively high number of eggs were laid on the surface of those beans where the amount of dust had been locally reduced by adults' movement and their pick up of DE. Therefore, several larvae tried to penetrate into these treated beans, causing a high larval density per partially cleaned bean. All these reasons lead to a progeny decline. PMID:12703482

Prasantha, B D Rohitha; Reichmuth, Ch; Büttner, C

2002-01-01

58

Earth  

NSDL National Science Digital Library

This NASA (National Aeronautics and Space Administration) planet profile provides data and images of the planet Earth. These data include planet size, orbit facts, distance from the Sun, rotation and revolution times, temperature, atmospheric composition, density, surface materials and albedo. Images with descriptions show Earth features such as the Ross Ice Shelf in Antarctica, Simpson Desert in Australia, Mt. Etna in Sicily, the Cassiar Mountains in Canada, the Strait of Gibraltar, Mississippi River, Grand Canyon, Wadi Kufra Oasis in Libya, and Moon images such as Hadley Rille, Plum Crater, massifs and Moon rocks. These images were taken with the Galileo Spacecraft and by the Apollo missions.

59

Ray Shielding  

NSDL National Science Digital Library

In this activity, students will gather data on space radiation shielding by observing a flashlight beam as it shines through different material, and by measuring, predicting, counting, and weighing the proposed materials. They will then analyze their data, select the most protective and lightweight material for radiation shielding in a spacecraft, and develop a conclusion based on their results. The activity is designed to accompany the Kids' Science News Network (KSNN) 21st Century Exlporer 30-second news break entitled 'What Would You Hear in a Weather Report From Mars?' The activity includes a teacher's guide and instructions for students, and a Spanish translation is available.

60

GCFR Plenum Shield Design: Shield Heterogeneity Experiment.  

National Technical Information Service (NTIS)

This report presents measurements of neutron fluxes made in the Shield Heterogeneity Study of at the Tower Shielding Facility (TSF) for the Gas Cooled Breeder Reactor (GCFR) shielding program. The study consisted of mockups of selective neutron streaming ...

F. J. Muckenthaler J. L. Hull J. J. Manning

1981-01-01

61

Thematic mapper research in the Earth sciences: Tectonic evaluation of the Nubian Shield of northeastern Sudan/southeastern Egypt using thematic mapper imagery  

NASA Astrophysics Data System (ADS)

The tectonic evaluation of the Nubian Shield using the Thematic Mapper (TM) imagery is progressing well and shows great promise. The TM tapes for the six LANDSAT 5 scenes covering the northern portion of the Red Sea hills were received, and preliminary maps and interpretations were made for most of the area. It is apparent that faulting and shearing associated with the major suture zones such as the Sol Hamed are clearly visible and that considerable detail can be seen. An entire quadrant of scene 173,45 was examined in detail using all seven bands, and every band combination was evaluated to best display the geology. A comparison was done with color ratio combinations and color combinations of the eigen vector bands to verify if band combinations of 7-red, 4-green, and 2-blue were indeed superior. There is no single optimum enhancement which provides the greatest detail for every image and no single combination of spectral bands for all cases, although bands 7, 4, and 2 do provide the best overall display. The color combination of the eigen vector bands proved useful in distinguishing fine detailed features.

1986-02-01

62

Rootless Shield -- Lava Flow  

USGS Multimedia Gallery

Rootless shields grow both in breadth and height through the accumulation of repeated overflows from the summits of the shields. In this photo, a stream of lava is flowing southward down the flank of this emergent shield....

2010-07-19

63

Cosmic Ray Interactions in Shielding Materials  

SciTech Connect

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.

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

2011-09-08

64

Magnetic shielding  

DOEpatents

A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.

Kerns, J.A.; Stone, R.R.; Fabyan, J.

1985-02-12

65

Magnetic shielding  

DOEpatents

A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines. 3 figs.

Kerns, J.A.; Stone, R.R.; Fabyan, J.

1987-10-06

66

INTOR Radiation Shielding for Personnel Access.  

National Technical Information Service (NTIS)

The INTOR reactor shield system consists of the blanket, bulk shield, penetration shield, component shield, and biological shield. The bulk shield consists of two parts: (a) the inboard shield; and (b) the outboard shield. The distinction between the diff...

Y. Gohar M. Abdou

1981-01-01

67

Gravity Scaling of a Power Reactor Water Shield.  

National Technical Information Service (NTIS)

A similarity analysis on a water-based reactor shield examined the effect of gravity on free convection between a reactor shield inner and outer vessel boundaries. Two approaches established similarity between operation on the Earth and the Moon: 1) direc...

J. B. Pearson R. S. Reid

2007-01-01

68

Shielding Effectiveness of Braided-Wire Shields  

Microsoft Academic Search

An analysis of the shielding effectiveness of braidedwire shields is made using the parameters of the woven wire and the theory of electromagnetic coupling through small irises. The coupling through the rhombic-shaped holes in the braid is approximated by using the electric and magnetic polarizabilities of elliptical holes of the same width and length as the rhombus. The analysis develops

EDWARD F. VANCE

1975-01-01

69

GCFR Plenum Shield Design: Exit Shield Experiment.  

National Technical Information Service (NTIS)

This report describes the integral flux, energy spectra, and dose rate measurements made for the Exit Shield Experiment at the Oak Ridge National Laboratory Tower Shielding Facility as part of the Gas Cooled Fast Breeder Reactor program. The source was th...

F. J. Muckenthaler J. L. Hull J. J. Manning

1981-01-01

70

Magnetic shielding design analysis  

SciTech Connect

Two passive magnetic-shielding-design approaches for static external fields are reviewed. The first approach uses the shielding solutions for spheres and cylinders while the second approach requires solving Maxwell's equations. Experimental data taken at LLNL are compared with the results from these shieldings-design methods, and improvements are recommended for the second method. Design considerations are discussed here along with the importance of material gaps in the shield.

Kerns, J.A.; LaPaz, A.D.; Fabyan, J.

1983-12-27

71

Drip Shield Emplacement Gantry Concept.  

National Technical Information Service (NTIS)

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 Gant...

2005-01-01

72

Migration of Activation Products from the Oak Ridge Spallation Neutron Source Facility Shield Berm on Chestnut Ridge on the Oak Ridge Reservation  

Microsoft Academic Search

This report was prepared as an account of work sponsored by an agency of the United States Government. Neitherthe United States Government nor any agency thereof, nor any of their employees, makes any warranty, express orimplied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness or anyinformation, apparatus, product, or process disclosed, or represents that its

L. R. Dole; J. O. Johnson; D. M. Hetrick; D. B. Watson; D. D. Huff; J. R. DeVore; G. S. McNealy; J. M. Barnes

73

Radiation shield requirements for manned nuclear propulsion space vehicles  

Microsoft Academic Search

Manned nuclear propulsion space vehicles require radiation shielding to protect the crew from a number of diverse radiation sources: the propulsion system reactor, the Earth’s Van Allen radiation belts, anomalously large solar proton events (ALSPEs), and galactic cosmic radiation (GCR). The sources are characterized not only in terms of species and energy spectrum, but also by frequency, duration, and probability

Paul H. Sager

1992-01-01

74

RADIATION SHIELDING DEVICE  

DOEpatents

ABS>A radiation shield that is suitable for the protection of personnel from both gamma rays and nentrons is described. The shield is comprised of a hollow wall and an aggregate consisting of iron and water in approximately equal amounts by volume substantially filling the wall. A means is provided to circulate the water through the wall to cool the shield when in use.

Wigner, E.P.; Young, G.J.

1958-09-23

75

RADIATION SHIELDING COMPOSITION  

DOEpatents

A light weight radiation shielding composition is described whose mechanical and radiological properties can be varied within wide limits. The composition of this shielding material consists of four basic ingredients: powder of either Pb or W, a plastic resin, a resin plasticizer, and a polymerization catalyst to promote an interaction of the plasticizer with the plastic resin. Air may be mixed into the above ingredients in order to control the density of the final composition. For equivalent gamma attenuation, the shielding composition weighs one-third to one-half as much as conventional Pb shielding. (AEC)

Dunegan, H.L.

1963-01-29

76

Shielding Structures for Interplanetary Human Mission  

NASA Astrophysics Data System (ADS)

Since the end of Apollo missions, human spaceflight has been limited to the Low Earth Orbit (LEO), inside the protective magnetic field of the Earth, because astronauts are, to the largest degree, protected from the harsh radiation environment of the interplanetary space. However, this situation will change when space exploration missions beyond LEO will become the real challenge of the human exploration program. The feasibility of these missions in the solar system is thus strongly connected to the capability to mitigate the radiation-induced biological effects on the crew during the journey and the permanence on the intended planet surface. Inside the International Space Station (ISS), the volumes in which the crew spends most of the time, namely the crew quarters are the only parts that implement dedicated additional radiation shielding made of polyethylene tiles designed for mitigating SPE effects. Furthermore, specific radiation shielding materials are often added to the described configuration to shield crew quarters or the entire habitat example of these materials are polyethylene, liquid hydrogen, etc. but, increasing the size of the exploration vehicles to bring humans beyond LEO, and without the magnetosphere protection, such approach is unsustainable because the mass involved is a huge limiting factor with the actual launcher engine technology. Moreover, shielding against GCR with materials that have a low probability of nuclear interactions and in parallel a high ionizing energy loss is not always the best solution. In particular there is the risk to increase the LET of ions arriving at the spacecraft shell, increasing their Radio-Biological Effectiveness. Besides, the production of secondary nuclei by projectile and target fragmentation is an important issue when performing an engineering assessment of materials to be used for radiation shielding. The goal of this work is to analyze different shielding solutions to increase as much as possible the radiation shielding power of the interplanetary habitat structures, like the spacecraft shell, minimizing the amount of mass used. From the radiation protection point of view the spacecraft shell is an interesting spacecraft system because it surrounds almost homogeneously all the habitat and it is typically composed by the Micrometeorites and Debris Protection Systems (MDPS), the Multilayer Insulation (MLI) for thermal control purposes, and the primary structure that offers the pressure containment functionality. Nevertheless, the spacecraft internal outfitting is important to evaluate the different shielded areas in the habitat. Using Geant4 Monte Carlo simulations toolkit through GRAS (Geant4 Radiation Analysis for Space) tool, different spacecraft structures will be analyzed for their shielding behavior in terms of fluxes, dose reduction and radiation quality, and for their implementation in a real pressurized module. Effects on astronauts and electronic equipments will be also assessed with respect to the standard aluminum structures.

Tracino, Emanuele; Lobascio, Cesare

2012-07-01

77

Shielding for reactors  

Microsoft Academic Search

A brief introductory discussion is given of the design of shielding for nuclear reactors. It includes consideration of design requirements, choice of materials and dimensions, nuclear reactions that affect the penetration, heating of the shielding and production of radioactivity in the coolant. Because the basic data available are insufficient for high accuracy in design calculation, the use of very complex

G C Laurence

1956-01-01

78

SHIELDING AGAINST SPACE RADIATION  

Microsoft Academic Search

A discussion of the problems in space radiation shielding is presented. ; The problem of penetrating protons is considered in an attempt to iliustrate the ; physical shieiding requirements for manned vehicles and to illuminate some of the ; gaps in present knowledge. Material and magnetic shielding are considered. ; (C.E.S.);

Madey

1963-01-01

79

NEUTRONIC REACTOR SHIELDING  

DOEpatents

A special hydrogenous concrete shielding for reactors is described. In addition to Portland cement and water, the concrete essentially comprises 30 to 60% by weight barytes aggregate for enhanced attenuation of fast neutrons. The biological shields of AEC's Oak Ridge Graphite Reactor and Materials Testing Reactor are particular embodiments.

Borst, L.B.

1961-07-11

80

Gamma ray detector shield  

DOEpatents

A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.

Ohlinger, R.D.; Humphrey, H.W.

1985-08-26

81

Shielding requirements for mammography.  

PubMed

Shielding requirements for mammography installations have been investigated. To apply the methodologies of NCRP Report No. 49, the scatter-to-incident ratio of a typical mammography beam was measured, and the broad beam transmission was calculated for several representative beam spectra. These calculations were found to compare favorably with published low kVp tungsten-targeted x-ray transmission through a variety of shielding materials. Radiation shielding tables were developed from the calculated transmissions through Pb, concrete, gypsum, steel, plate glass, and water, using a technique which eliminates the "add one HVL" rule. It is concluded that Mo-targeted x-ray beams operated at 35 kVp require half the shielding of W-targeted beams operated at 50 kVp, and that adequate, cost-effective shielding calculations will consider alternatives to Pb. PMID:3623916

Simpkin, D J

1987-09-01

82

Large shield volcanoes on the Moon  

NASA Astrophysics Data System (ADS)

volcanic style of the Moon has long been understood to consist almost exclusively of flood basalts erupted from fissures along with minor pyroclastic activity; large central vent shield volcanoes that characterize basaltic volcanism on the other terrestrial planets appeared to be absent. Small (few kilometers diameter) central vent constructs have long been recognized in the lunar maria and often are found clustered in fields throughout the lunar maria. New global topographic data from the LOLA and LROC instruments on LRO reveal that almost all of these volcanic complexes on the Moon occur on large, regional topographic rises in the lunar maria, tens to hundreds of kilometers in extent and between several hundred to several thousand meters high. We propose that these topographic swells are shield volcanoes and are the lunar equivalents of the large basaltic shields found on the Earth, Venus, and Mars. The newly recognized lunar shields are found peripheral to the large, deeply flooded impact basins Imbrium and Serenitatis, suggesting a genetic relation to those features. Loading of the lithosphere by these basalt-filled basins may be responsible for inducing a combination of flexural and membrane stress, inducing a pressure distribution on vertically oriented dikes favorable to magma ascent. This condition would occur in a zone annular to the large circular loads produced by the basins, where the shield volcanoes occur.

Spudis, Paul D.; McGovern, Patrick J.; Kiefer, Walter S.

2013-05-01

83

Galactic and Solar Cosmic Ray Shielding in Deep Space  

NASA Astrophysics Data System (ADS)

An analysis of the radiation hazards in support of NASA deep space exploration activities is presented. The emphasis is on materials required for radiation protection shielding. Aluminum has been found to be a poor shield material when dose equivalent is used with exposure limits for low Earth orbit (LEO) as a guide for shield requirements. Because the radiation issues are cost related-the parasitic shield mass has high launch costs, the use of aluminum as a basic construction material is clearly not cost-effective and alternate materials need to be developed. In this context, polyethylene is examined as a potentially useful material and demonstrates important advantages as an alternative to aluminum construction. Although polyethylene is useful as a shield material, it may not meet other design criteria (strength, stability, thermal); other polymer materials must be examined.

Wilson, John W.; Cucinotta, Francis A.; Tai, H.; Simonsen, Lisa C.; Shinn, Judy L.; Thibeault, Shelia; Kim, M. Y.

1997-12-01

84

A high-performance magnetic shield with large length-to-diameter ratio.  

PubMed

We have demonstrated a 100-fold improvement in the magnetic field uniformity on the axis of a large aspect ratio, cylindrical, mumetal magnetic shield by reducing discontinuities in the material of the shield through the welding and re-annealing of a segmented shield. The three-layer shield reduces Earth's magnetic field along an 8 m region to 420 ?G (rms) in the axial direction, and 460 and 730 ?G (rms) in the two transverse directions. Each cylindrical shield is a continuous welded tube which has been annealed after manufacture and degaussed in the apparatus. We present both experiments and finite element analysis that show the importance of uniform shield material for large aspect ratio shields, favoring a welded design over a segmented design. In addition, we present finite element results demonstrating the smoothing of spatial variations in the applied magnetic field by cylindrical magnetic shields. Such homogenization is a potentially useful feature for precision atom interferometric measurements. PMID:22755663

Dickerson, Susannah; Hogan, Jason M; Johnson, David M S; Kovachy, Tim; Sugarbaker, Alex; Chiow, Sheng-wey; Kasevich, Mark A

2012-06-01

85

MEANS FOR SHIELDING REACTORS  

DOEpatents

A reactor of the heterageneous, heavy water moderated type is described. The reactor is comprised of a plurality of vertically disposed fuel element tubes extending through a tank of heavy water moderator and adapted to accommodate a flow of coolant water in contact with the fuel elements. A tank containing outgoing coolant water is disposed above the core to function is a radiation shield. Unsaturated liquid hydrocarbon is floated on top of the water in the shield tank to reduce to a minimum the possibility of the occurrence of explosive gaseous mixtures resulting from the neutron bombardment of the water in the shield tank.

Garrison, W.M.; McClinton, L.T.; Burton, M.

1959-03-10

86

iSHIELD - A Line Source Application of SHIELD11  

SciTech Connect

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.

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

2006-04-27

87

Adhesive particle shielding  

DOEpatents

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.

Klebanoff, Leonard Elliott (Dublin, CA); Rader, Daniel John (Albuquerque, NM); Walton, Christopher (Berkeley, CA); Folta, James (Livermore, CA)

2009-01-06

88

Analysis of shield tunnel  

Microsoft Academic Search

SUMMARY This paper proposes a two-dimensional finite element model for the analysis of shield tunnels by taking into account the construction process which is divided into four stages. The soil is assumed to behave as an elasto-plastic medium whereas the shield is simulated by beam-joint discontinuous model in which curved beam elements and joint elements are used to model the

W. Q. Ding; Z. Q. Yue; L. G. Tham; H. H. Zhu; C. F. Lee; T. Hashimoto

2004-01-01

89

SHIELD certification package  

SciTech Connect

Certification as applied to existing computer codes includes the verification and validation process, placing the code in configuration control, establishing user qualification standards and training requirements. All software intended for use in critical calculations must be certified. This report is intended to fulfill the requirements for the certification of the SHIELD, SHLDED, GEDIT, GENPRT, FIPROD, FPCALC, and PROCES modules of the SHIELD system built February, 1992, by W.S. Parks. These modules are used for burnup, cooling, separate, and edit calculations.

Boman, C.

1992-02-01

90

Martian regolith as space radiation shielding.  

PubMed

In current Mars scenario descriptions, an entire mission is estimated to take 500-1000 days round trip with a 100-600 day stay time on the surface. To maintain radiation dose levels below permissible limits, dose estimates must be determined for the entire mission length. With extended crew durations anticipated on Mars, the characterization of the radiation environment on the surface becomes a critical aspect of mission planning. The most harmful free-space radiation is due to high energy galactic cosmic rays (GCR) and solar flare protons. The carbon dioxide atmosphere of Mars has been estimated to provide a sufficient amount of shielding from these radiative fluxes to help maintain incurred doses below permissible limits. However, Mars exploration crews are likely to incur a substantial dose while in transit to Mars that will reduce the allowable dose that can be received while on the surface. Therefore, additional shielding may be necessary to maintain short-term dose levels below limits or to help maintain career dose levels as low as possible. By utilizing local resources, such as Martian regolith, shielding materials can be provided without excessive launch weight requirements from Earth. The scope of this synopsis and of Ref. 3 focuses on presenting our estimates of surface radiation doses received due to the transport and attenuation of galactic cosmic rays and February 1956 solar flare protons through the Martian atmosphere and through additional shielding provided by Martian regolith. PMID:11537624

Simonsen, L C; Nealy, J E; Townsend, L W; Wilson, J W

91

Magnetic shielding of a large volume for an experiment on quasi free neutron oscillation  

Microsoft Academic Search

Results of the shielding against the Earth's magnetic field on a large volume are given. The experimental procedure is based on a multilayer mu-metal shield and a series of correcting electric coils. A final average value of (8.1+\\/-4.4) mG is obtained in a volume of about 20 m3.

G. Bressi; M. Cambiaghi; A. Lanza; F. Mauri; A. Piazzoli; D. Scannicchio; P. Torre; P. Beltrami; C. Casella; E. Imbres; T. Locatelli

1986-01-01

92

Self-Cleaning Transparent Dust Shields for Protecting Solar Panels and Other Devices  

Microsoft Academic Search

The development of transparent flexible dust shields using both single- and three-phase electrodynamic shields is reported here for possible application on Mars and Earth to minimize obscuration of solar panels from the deposition of dust. The electrodynamic screens (EDS) are made of transparent plastic sheets, such as polyethylene terephthalate (PET) for its UV radiation resistance, and a set of parallel

M. K. Mazumder; R. Sharma; A. S. Biris; J. Zhang; C. Calle; M. Zahn

2007-01-01

93

LOFT. Contextual view of north side of shielded roadway (TAN719) ...  

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

LOFT. Contextual view of north side of shielded roadway (TAN-719) as it looked during use of FET facilities. Camera facing southwest. Sign over door says, "Contained Test Facility." Note earth shielding. Date: March 2004. INEEL negative no. HD-39-3-2 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

94

Sea-level proxies extracted from GPR reflection data collected across recently formed berm, beach ridge and swale deposits on the island of Anholt, Denmark  

NASA Astrophysics Data System (ADS)

GPR reflection data have been collected across the most recent part of a berm, beach ridge and swale system formed during the last 130 years on the northern coast of the island of Anholt, the Kattegat, Denmark. The reflected arrivals have a peak frequency of about 250 MHz and they image the subsurface with a vertical resolution of 0.1-0.2 m to a maximum depth of 5 m below the surface. The berm and beach ridges with maximum heights of about 1.8 m and 1.5 m, respectively, appear as mounded features in the GPR sections. The berm ridge also contains low-angle, seaward dipping reflections. Similar sea-ward dipping reflections are also observed below swales, and current swale surfaces appear to constitute erosion surfaces. Reflections downlapping on a package of reflections, which is interpreted to be representative of upper shoreface deposits, are suggested to constitute good proxies of sea level. Tamura et al. (2008) suggested that similar downlapping reflections may represent a depth level of about 1 m below the mean sea level based on investigations of the Kujukuri strand plain in eastern Japan. We have made 17 depth readings of such downlaps along our 159-m-long profile. The average depth of these downlap points is 0.003 m below present mean sea level (pmsl). Individual readings fall in the range of -0.5 m to +0.5 above pmsl, consistent with the majority of current, annual sea-level variations as recorded by the Danish Maritime Safety Administration at a position about 50 km southwest of Anholt. The mean sea level has changed insignificantly in the study area during ridge formation, and we assume that these proxies may form a strong basis for constructing palaeo-sea level curves for fossil (ages of up to about 7500 years), raised beach-ridge systems along the shores of the Kattegat and the Baltic Sea. Reference T. Tamura, F. Murakami, F. Nanayama, K. Watanabe, Y. Saito, 2008. Ground-penetrating radar profiles of Holocene raised-beach deposits in the Kujukuri strand plain, Pacific coast of eastern Japan, Marine Geology, 248, 11-27.

Nielsen, L.; Clemmensen, L. B.

2009-04-01

95

Reactor head shielding apparatus  

SciTech Connect

This patent describes a nuclear reactor head shielding apparatus for mounting on spaced reactor head lifting members radially inwardly of the head bolts. It comprises a frame of sections for mounting on the lifting members and extending around the top central area of the head, mounting means for so mounting the frame sections, including downwardly projecting members on the frame sections and complementary upwardly open recessed members for fastening to the lifting members for receiving the downwardly projecting members when the frame sections are lowered thereto with lead shielding supported thereby on means for hanging lead shielding on the frame to minimize radiation exposure or personnel working with the head bolts or in the vicinity thereof.

Schukei, G.E.; Roebelen, G.J.

1992-01-28

96

Radiation shielding composition  

DOEpatents

A composition for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm.sup.3 and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile.

Quapp, William J. (Idaho Falls, ID); Lessing, Paul A. (Idaho Falls, ID)

1998-01-01

97

Radiation shielding composition  

DOEpatents

A composition is disclosed for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm{sup 3} and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile. 5 figs.

Quapp, W.J.; Lessing, P.A.

1998-07-28

98

Radiation shielding composition  

DOEpatents

A composition for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm.sup.3 and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile.

Quapp, William J. (Idaho Falls, ID); Lessing, Paul A. (Idaho Falls, ID)

2000-12-26

99

Shielding of relativistic protons.  

PubMed

Protons are the most abundant element in the galactic cosmic radiation, and the energy spectrum peaks around 1 GeV. Shielding of relativistic protons is therefore a key problem in the radiation protection strategy of crewmembers involved in long-term missions in deep space. Hydrogen ions were accelerated up to 1 GeV at the NASA Space Radiation Laboratory, Brookhaven National Laboratory, New York. The proton beam was also shielded with thick (about 20 g/cm2) blocks of lucite (PMMA) or aluminium (Al). We found that the dose rate was increased 40-60% by the shielding and decreased as a function of the distance along the axis. Simulations using the General-Purpose Particle and Heavy-Ion Transport code System (PHITS) show that the dose increase is mostly caused by secondary protons emitted by the target. The modified radiation field after the shield has been characterized for its biological effectiveness by measuring chromosomal aberrations in human peripheral blood lymphocytes exposed just behind the shield block, or to the direct beam, in the dose range 0.5-3 Gy. Notwithstanding the increased dose per incident proton, the fraction of aberrant cells at the same dose in the sample position was not significantly modified by the shield. The PHITS code simulations show that, albeit secondary protons are slower than incident nuclei, the LET spectrum is still contained in the low-LET range (<10 keV/microm), which explains the approximately unitary value measured for the relative biological effectiveness. PMID:17256178

Bertucci, A; Durante, M; Gialanella, G; Grossi, G; Manti, L; Pugliese, M; Scampoli, P; Mancusi, D; Sihver, L; Rusek, A

2007-01-26

100

Passive radiation shielding considerations for the proposed space elevator  

Microsoft Academic Search

The Earth's natural van Allen radiation belts present a serious hazard to space travel in general, and to travel on the space elevator in particular. The average radiation level is sufficiently high that it can cause radiation sickness, and perhaps death, for humans spending more than a brief period of time in the belts without shielding. The exact dose and

A. M. Jorgensen; S. E. Patamia; B. Gassend

2007-01-01

101

Determination of the cutterhead torque for EPB shield tunneling machine  

Microsoft Academic Search

Cutterhead torque is an important parameter for the design and operation of earth pressure balance (EPB) shields. Based on the analysis of several completed project cases from job sites, the conventional torque determination model based on experimentation proves rough enough to be improved. Composition and corresponding calculation method of cutterhead torque are presented, taking into account of cutterhead structure, cutting

Hu Shi; Huayong Yang; Guofang Gong; Lintao Wang

2011-01-01

102

Radiation shield requirements for manned nuclear propulsion space vehicles  

Microsoft Academic Search

Manned nuclear propulsion space vehicles require radiation shielding to protect the crew from a number of diverse radiation sources: the propulsion system reactor, the Earth's Van Allen radiation belts, anomalously large solar proton events (ALSPEs), and galactic cosmic radiation (GCR). The sources are characterized not only in terms of species and energy spectrum, but also by frequency, duration, and probability

Paul H. Sager

1992-01-01

103

Composition for radiation shielding  

DOEpatents

A composition for use as a radiation shield. The shield has a depleted urum core for absorbing gamma rays and a bismuth coating for preventing chemical corrosion and absorbing gamma rays. Alternatively, a sheet of gadolinium may be positioned between the uranium core and the bismuth coating for absorbing neutrons. The composition is preferably in the form of a container for storing materials that emit radiation such as gamma rays and neutrons. The container is preferably formed by casting bismuth around a pre-formed uranium container having a gadolinium sheeting, and allowing the bismuth to cool. The resulting container is a structurally sound, corrosion-resistant, radiation-absorbing container.

Kronberg, James W. (Aiken, SC)

1994-01-01

104

Glove box shield  

DOEpatents

According to the present invention, a shield for a glove box housing radioactive material is comprised of spaced apart clamping members which maintain three overlapping flaps in place therebetween. There is a central flap and two side flaps, the side flaps overlapping at the interior edges thereof and the central flap extending past the intersection of the side flaps in order to insure that the shield is always closed when the user withdraws his hand from the glove box. Lead loaded neoprene rubber is the preferred material for the three flaps, the extent of lead loading depending upon the radiation levels within the glove box.

Brackenbush, Larry W. (Richland, WA); Hoenes, Glenn R. (Richland, WA)

1981-01-01

105

Bumper shield analysis  

SciTech Connect

To initially examine the effectiveness of a shield surrounding a reentry vehicle, we used the hypervelocity hydrodynamic impact code, LASOIL. We completed a four-by-four matrix of 16 two-dimensional numerical impact simulations of 1-g tungsten cylinders striking circular plates. The variable parameters were the projectile impact velocity (10, 20, 40, and 80 km/s) and the plate thickness (1, 2, 4, and 8 mm). In each case, the projectile was destroyed in the impact. The shield was penetrated but retained negliible momentum from the impact. The resultant debris cloud was low-density debris and vapor.

Oyer, A.T.

1986-07-01

106

Shielded Enclosures for Experimental Studies of Shielding Topology.  

National Technical Information Service (NTIS)

The report discusses the effort to provide shielded enclosures for EMP experimental studies of shielding topology. Section I discusses the theoretical modeling for which scattering matrices of subshields and their norms are used to relate the internal sig...

F. C. Yang K. S. H. Lee S. A. Kokorowski C. E. Baum J. Hamm

1984-01-01

107

EMP Shielding Using Multilayer Film.  

National Technical Information Service (NTIS)

This program was to develop and fabricate a low cost composite shielding material (Multishield) that is capable of providing shielding against magnetic fields, including high strength fields. A continuous horizontal web production machine was manufactured...

W. J. Biter

2000-01-01

108

Materials for electromagnetic interference shielding  

Microsoft Academic Search

Materials for the electromagnetic interference (EMI) shielding of electronics and radiation sources are reviewed, with emphasis\\u000a on composite materials and resilient EMI gasket materials, which shield mainly by reflection of the radiation at a high frequency.

D. D. L. Chung

2000-01-01

109

SSC environmental radiation shielding  

SciTech Connect

The environmental radiation shielding requirements of the SSC have been evaluated using currently available computational tools that incorporate the well known processes of energy loss and degradation of high energy particles into Monte Carlo computer codes. These tools permit determination of isodose contours in the matter surrounding a source point and therefore the specification of minimum thicknesses or extents of shielding in order to assure annual dose equivalents less than some specified design amount. For the general public the annual dose equivalent specified in the design is 10 millirem, small compared to the dose from naturally occurring radiation. The types of radiation fall into two classes for the purposes of shielding determinations-hadrons and muons. The sources of radiation at the SSC of concern for the surrounding environment are the interaction regions, the specially designed beam dumps into which the beams are dumped from time to time, and beam clean-up regions where stops remove the beam halo in order to reduce experimental backgrounds. A final, unlikely source of radiation considered is the accidental loss of the full beam at some point around the ring. Conservative choices of a luminosity of 10{sup 34} cm{sup {minus}2}s{sup {minus}1} and a beam current three times design have been made in calculating the required shielding and boundaries of the facility. In addition to determination of minimum distances for the annual dose equivalents, the question of possible radioactivity produced in nearby wells or in municipal water supplies is addressed. The designed shielding distances and beam dumps are such that the induced radioactivity in ground water is safely smaller than the levels permitted by EPA and international agencies.

Jackson, J.D. [ed.

1987-07-01

110

Aluminum Foil Shield Effectiveness for Electronic Cables.  

National Technical Information Service (NTIS)

Historically, shielding of electronic cables has been expressed in terms of shield coverage. The numeric value used to delineate shield coverage corresponded to the actual area of the conductors covered by the cable shield. Generally, the larger the perce...

M. R. Lombardo

1983-01-01

111

Shielding of substations against direct lightning strokes by shield wires  

SciTech Connect

A new analysis for shielding outdoor substations against direct lightning strokes by shield wires is proposed. The basic assumption of this proposed method is that any lightning stroke which penetrates the shields will cause damage. The second assumption is that a certain level of risk of failure must be accepted, such as one or two failures per 100 years. The proposed method, using electrogeometric model, was applied to design shield wires for two outdoor substations: (1) 161-kV/69-kV station, and (2) 500-kV/161-kV station. The results of the proposed method were also compared with the shielding data of two other substations.

Chowdhuri, P. (Tennessee Technological Univ., Cookeville, TN (United States))

1994-01-01

112

Novel shielding materials for space and air travel.  

PubMed

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. PMID:16717109

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

2006-05-22

113

Distributed acoustic conversation shielding system  

US Patent & Trademark Office Database

A conversation shielding system comprises sensors that detect the location of a confidential conversation and the presence and location of a potential eavesdropper, audio output devices that produce masking sounds to shield the conversation from the eavesdropper, and a controller that automatically controls the operation of the output devices in response to data from the sensors. An optional portable controller may manually engage the system. A method for shielding conversation comprises identifying a conversation to be shielded, detecting a potential eavesdropper, automatically determining masking sound types, locations and volume that will shield the conversation, directing emission of masking sounds from at least one audio output device in order to shield the conversation, including adjusting the masking sound type, location, and volume in response to movement of the conversation or the eavesdropper, and continuing to shield the conversation until it ends or the eavesdropper is no longer detected.

Paradiso; Joseph A. (Medford, MA); Ono; Yasuhiro (Saitama, JP)

2012-07-24

114

Grounding and shielding techniques  

SciTech Connect

Grounding and shielding of electrical components and subsystems have always been a source of nuisance problems. In systems where large amounts of energy are moved in short, high power pulses, these problems may no longer be of nuisance value, but may become critical to the survival and well being of sensitive subsystems and adjacent electronics which may be functionally unreleated to the pulse power system. As it happens, most of the problems associated with grounding and shielding turn out to be conceptually simple but, similar to computer systems, become lost in a maze of complexity and a jungle of confusion. It is the intention of this presentation to illuminate those practices which will lead to problems later and to remove some of the apparent mystery from the sources of electromagnetic interference (EMI). Also, a set of rules will be presented which hopefully will help to prevent or solve problems derived from EMI.

Burkes, T.R.

1980-01-01

115

Composition for radiation shielding  

DOEpatents

A composition for use as a radiation shield is disclosed. The shield has a depleted uranium core for absorbing gamma rays and a bismuth coating for preventing chemical corrosion and absorbing gamma rays. Alternatively, a sheet of gadolinium may be positioned between the uranium core and the bismuth coating for absorbing neutrons. The composition is preferably in the form of a container for storing materials that emit radiation such as gamma rays and neutrons. The container is preferably formed by casting bismuth around a pre-formed uranium container having a gadolinium sheeting, and allowing the bismuth to cool. The resulting container is a structurally sound, corrosion-resistant, radiation-absorbing container. 2 figs.

Kronberg, J.W.

1994-08-02

116

Multilayer radiation shield  

DOEpatents

A power generation system including: a generator including a rotor including a superconductive rotor coil coupled to a rotatable shaft; a first prime mover drivingly coupled to the rotatable shaft; and a thermal radiation shield, partially surrounding the rotor coil, including at least a first sheet and a second sheet spaced apart from the first sheet by centripetal force produced by the rotatable shaft. A thermal radiation shield for a generator including a rotor including a super-conductive rotor coil including: a first sheet having at least one surface formed from a low emissivity material; and at least one additional sheet having at least one surface formed from a low emissivity material spaced apart from the first sheet by centripetal force produced by the rotatable shaft, wherein each successive sheet is an incrementally greater circumferential arc length and wherein the centripetal force shapes the sheets into a substantially catenary shape.

Urbahn, John Arthur (Saratoga Springs, NY); Laskaris, Evangelos Trifon (Niskayuna, NY)

2009-06-16

117

Electron beam shielding  

Microsoft Academic Search

The use of electron beams (EBs), particularly for melting, evaporating, and refining metals, can produce high levels of x-rays. In fact, under ultravacuum, as generally is the case, the conditions for producing x-rays are similar to that of conventional x-rays tubes. Therefore, providing adequate shielding against these x-rays must be considered an important part of EB operations. This paper presents

1990-01-01

118

Shielding Benchmark Computational Analysis  

SciTech Connect

Over the past several decades, nuclear science has relied on experimental research to verify and validate information about shielding nuclear radiation for a variety of applications. These benchmarks are compared with results from computer code models and are useful for the development of more accurate cross-section libraries, computer code development of radiation transport modeling, and building accurate tests for miniature shielding mockups of new nuclear facilities. When documenting measurements, one must describe many parts of the experimental results to allow a complete computational analysis. Both old and new benchmark experiments, by any definition, must provide a sound basis for modeling more complex geometries required for quality assurance and cost savings in nuclear project development. Benchmarks may involve one or many materials and thicknesses, types of sources, and measurement techniques. In this paper the benchmark experiments of varying complexity are chosen to study the transport properties of some popular materials and thicknesses. These were analyzed using three-dimensional (3-D) models and continuous energy libraries of MCNP4B2, a Monte Carlo code developed at Los Alamos National Laboratory, New Mexico. A shielding benchmark library provided the experimental data and allowed a wide range of choices for source, geometry, and measurement data. The experimental data had often been used in previous analyses by reputable groups such as the Cross Section Evaluation Working Group (CSEWG) and the Organization for Economic Cooperation and Development/Nuclear Energy Agency Nuclear Science Committee (OECD/NEANSC).

Hunter, H.T.; Slater, C.O.; Holland, L.B.; Tracz, G.; Marshall, W.J.; Parsons, J.L.

2000-09-17

119

Simplified model for solar cosmic ray exposure in manned Earth orbital flights  

NASA Astrophysics Data System (ADS)

A simple calculational model is derived for use in estimating solar cosmic ray exposure to critical body organs in low-Earth orbit at the center of a large spherical shield of fixed thickness. The effects of the Earth's geomagnetic field, including storm conditions and the astronauts' self-shielding, are evaluated explicitly. The magnetic storm model is keyed to the planetary index Kp.

Wilson, John W.; Khandelwal, Govind S.; Shinn, Judy L.; Nealy, John E.; Townsend, Lawrence W.; Cucinotta, Francis A.

1990-05-01

120

Justification for Shielded Receiver Tube Additional Lead Shielding  

SciTech Connect

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.

BOGER, R.M.

2000-04-11

121

Radiation shielding quality assurance  

NASA Astrophysics Data System (ADS)

For the radiation shielding quality assurance, the validity and reliability of the neutron transport code MCNP, which is now one of the most widely used radiation shielding analysis codes, were checked with lot of benchmark experiments. And also as a practical example, follows were performed in this thesis. One integral neutron transport experiment to measure the effect of neutron streaming in iron and void was performed with Dog-Legged Void Assembly in Knolls Atomic Power Laboratory in 1991. Neutron flux was measured six different places with the methane detectors and a BF-3 detector. The main purpose of the measurements was to provide benchmark against which various neutron transport calculation tools could be compared. Those data were used in verification of Monte Carlo Neutron & Photon Transport Code, MCNP, with the modeling for that. Experimental results and calculation results were compared in both ways, as the total integrated value of neutron fluxes along neutron energy range from 10 KeV to 2 MeV and as the neutron spectrum along with neutron energy range. Both results are well matched with the statistical error +/-20%. MCNP results were also compared with those of TORT, a three dimensional discrete ordinates code which was developed by Oak Ridge National Laboratory. MCNP results are superior to the TORT results at all detector places except one. This means that MCNP is proved as a very powerful tool for the analysis of neutron transport through iron & air and further it could be used as a powerful tool for the radiation shielding analysis. For one application of the analysis of variance (ANOVA) to neutron and gamma transport problems, uncertainties for the calculated values of critical K were evaluated as in the ANOVA on statistical data.

Um, Dallsun

122

Watching a disappearing shield  

SciTech Connect

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.

Stolarski, R.S.

1988-10-01

123

Passive Shielding in CUORE  

SciTech Connect

The nature of neutrino mass is one of the friontier problems of fundamental physics. Neutrinoless Double Beta Decay (0{nu}DBD) is a powerful tool to investigate the mass hierarchy and possible extensions of the Standard Model. CUORE is a 1-Ton next generation experiment, made of 1000 Te bolometers, aiming at reaching a background of 0.01 (possibly 0.001) counts keV-1kg-1y-1 and therefore a mass sensitivity of few tens of meV The background contribution due to environmental neutrons, muon-induced neutrons in the shieldings and external gamma is discussed.

Bellini, F.; Cosmelli, C.; Dafinei, I.; Diemoz, S.; Faccini, R.; Ferroni, F.; Gargiulo, C.; Longo, E.; Morganti, S.; Tomei, C.; Vignati, M. [Dipartimento di Fisica dell'Universita di Roma La Sapienza e Sezione di Roma dell'INFN, Roma I-00185 (Italy); Alessandria, F. [INFN - Sezione di Milano, Milan I-20133 (Italy); Andreotti, E.; Foggetta, L.; Giuliani, A.; Pedretti, M.; Sangiorgio, S. [Dipartimento di Fisica e Matematica dell'Universita dell'Insubria e Sezione di Milano dell'INFN, Como I-22100 (Italy); Ardito, R. [Dipartimento di Fisica dell'Universita di Milano-Bicocca e Sezione di Milano Bicocca dell'INFN, Milan I-2016 (Italy); Dipartimento di Ingegneria Strutturale del Politecnico di Milano, Milano I-20133 (Italy); Arnaboldi, C.; Brofferio, C. [Dipartimento di Fisica dell'Universita di Milano-Bicocca e Sezione di Milano Bicocca dell'INFN, Milan I-2016 (Italy)] (and others)

2007-03-28

124

Actively driven thermal radiation shield  

DOEpatents

A thermal radiation shield for cooled portable gamma-ray spectrometers. The thermal radiation shield is located intermediate the vacuum enclosure and detector enclosure, is actively driven, and is useful in reducing the heat load to mechanical cooler and additionally extends the lifetime of the mechanical cooler. The thermal shield is electrically-powered and is particularly useful for portable solid-state gamma-ray detectors or spectrometers that dramatically reduces the cooling power requirements. For example, the operating shield at 260K (40K below room temperature) will decrease the thermal radiation load to the detector by 50%, which makes possible portable battery operation for a mechanically cooled Ge spectrometer.

Madden, Norman W. (Livermore, CA); Cork, Christopher P. (Pleasant Hill, CA); Becker, John A. (Alameda, CA); Knapp, David A. (Livermore, CA)

2002-01-01

125

EXAMPLES OF RADIATION SHIELDING MODELS  

SciTech Connect

The attached pictures are examples of shielding models used by WSMS. The models were used in shielding evaluations for Tank 50 pump replacement. They show the relative location of shielding to radiation sources for pumps and pipes. None of the calculations that were associated with these models involved UCNI. The last page contains two pictures from a shielding calculation for the saltstone area. The upper picture is a conceptual drawing. The lower picture is an image copied from the website of a supplier for the project.

Willison, J

2006-07-27

126

Galactic cosmic ray abundances and spectra behind defined shielding.  

PubMed

LET spectra have been measured for lunar missions and for several near Earth orbits ranging from 28 degrees to 83 degrees inclination. In some of the experiments the flux of GCR was determined separately from contributions caused by interactions in the detector material. Results of these experiments are compared to model calculations. The general agreement justifies the use of the model to calculate GCR fluxes. The magnitude of variations caused by solar modulation, geomagnetic shielding, and shielding by matter determined from calculated LET spectra is generally in agreement with experimental data. However, more detailed investigations show that there are some weak points in modeling solar modulation and shielding by material. These points are discussed in more detail. PMID:11540030

Heinrich, W; Benton, E V; Wiegel, B; Zens, R; Rusch, G

1994-10-01

127

PATHFINDER ATOMIC POWER PLANT RADIATION SHIELDING STUDY  

Microsoft Academic Search

Alternate concepts studied for the various shielding requirements in the ; Pathfinder Atomic Power Plant are described. It is concluded that a concrete ; shield surrounding the reactor pressure vessel is an adequate biological shield. ; This shield is made up of two parts: an outer two foot section which is both ; shield and structaral support for the various

R. Corcoran; H. C. Crumpacker; D. M. Leppke

1959-01-01

128

PBF Cubicle 13. Shield wall details illustrate shielding technique of ...  

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

PBF Cubicle 13. Shield wall details illustrate shielding technique of stepped penetrations and brick layout scheme for valve stem extension sleeve. Aerojet Nuclear Company. Date: May 1976. INEEL index no. 761-0620-00-400-195280 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

129

Hot-Water Worms May Use Bacteria as Shield  

NSDL National Science Digital Library

This National Geographic news article highlights research being done to study the Pompeii worm (Alvinella pompejana), the most heat tolerant complex organism on Earth, and its microscopic symbionts. Bacteria on the worms' backs act like firefighters' blankets, shielding the worms from intermittent blasts of hot, metal-rich water. Scientists are currently characterizing the chemistry of the vent environment by sequencing a large amount of DNA from the bacterial community-the metagenome. The page includes links to related National Geographic sites.

Roach, John

2009-06-17

130

EMP Coupling Through Cable Shields  

Microsoft Academic Search

Recent research in electromagnetic coupling between the interior and exterior of coaxial cables is described. Both tubular shields and shields with apertures are discussed with reference to the physical coupling mechanisms and their mathematical representations in terms of transmission-line models.

Kendali Casey; Edward Vance

1978-01-01

131

Unintentional radiation from shielded transformers  

Microsoft Academic Search

It is shown experimentally that a typical shielded broadband transformer intended for bulk current injection measurements radiates far-field electromagnetic energy. This radiation occurs in spite of the shield and is distinct from any radiation due to common mode currents on the exterior of the coaxial feed transmission line. The radiation patterns presented here taken together with previous results which showed

James McLean; Robert Sutton

2010-01-01

132

Design experience: CRBRP radiation shielding  

Microsoft Academic Search

The Clinch River Breeder Reactor Plant (CRBRP) is being designed as a fast breeder demonstration project in the U.S. Liquid Metal Fast Breeder Reactor (LMFBR) program. Radiation shielding design of the facility consists of a comprehensive design approach to assure compliance with design and government regulatory requirements. Studies conducted during the CRBRP design process involved the aspects of radiation shielding

R. K. Disney; T. C. Chan; F. G. Gallo; L. R. Hedgecock; C. A. McGinnis; G. N. Wrights

1978-01-01

133

Aerodynamic Fastener Shield for Turbomachine.  

National Technical Information Service (NTIS)

A fastener shield for use in a fluid flow path within a gas turbine engine for reducing fluid drag and heating generated by fluid flow over a plurality of circumferentially spaced fasteners. The fastener shield has a radially-extending, downstream-facing ...

J. Senyo M. J. Epstein W. C. Anderson Z. Dong

2004-01-01

134

Lunar Surface Reactor Shielding Study  

Microsoft Academic Search

A nuclear reactor system could provide power to support long term human exploration of the moon. Such a system would require shielding to protect astronauts from its emitted radiations. Shielding studies have been performed for a Gas Cooled Reactor system because it is considered to be the most suitable nuclear reactor system available for lunar exploration, based on its tolerance

Shawn Kang; Ronald Lipinski; William McAlpine

2006-01-01

135

Aladdin upgrade design study: shielding  

SciTech Connect

The object of this shielding is to examine all aspects of Aladdin operation to ensure that adequate shielding is provided to meet the design objectives. To do this, we will look at shielding necessary for radiation produced during the injection process, during normal loss of the stored beam and during accidental loss of the stored beam. It will therefore be necessary to specify shielding not only at the ring, but also along the injection line and the optical beam lines. We will also give special attention to the occupation of the accelerator Vault during injection as this may be a desirable design option. In effect, two shielding plans will be presented, permitting estimates of cost and space requirements for both.

Swanson, W.P.; DeLuca, P.M. Jr.; Otte, R.A.; Schilthelm, S.W.

1985-04-23

136

A historically significant shield for in vivo measurements.  

PubMed

Due to the ubiquitous nature of ionizing radiation, in vivo measurement systems designed to measure low levels of radionuclides in people are usually enclosed within a high-density shield. Lead, steel, earth, and water are just some of the materials that have been and are being used to shield the detectors from radiations of cosmic, atmospheric, man-made, and terrestrial origin. At many Department of Energy sites, the counting room shields are constructed of pre-World War II steel to reduce the background levels in order to perform measurements that have low minimum detectable activities. The pre-World War II steel is commonly called low background steel in the in vivo industry vernacular. The low background descriptor comes from the fact the steel was manufactured prior to the beginning of atmospheric testing of nuclear weapons in the 1940's. Consequently, the steel is not likely to be contaminated with fission or activation products from fallout. For high energy photons (600 keV < E < 1500 keV), 30 cm of steel shielding significantly reduces the measured background radiation levels. This is the story of the unique steel that began as the hull of the U.S.S. Indiana and now forms a shielded room at the In Vivo Radiobioassay and Research Facility in Richland, Washington. PMID:17630635

Lynch, Timothy P

2007-08-01

137

NEUTRON SHIELDING STRUCTURE  

DOEpatents

A lightweight neutron shielding structure comprises a honeycomb core which is filled with a neutron absorbing powder. The honeycomb core is faced with parallel planar facing sheets to form a lightweight rigid unit. Suitable absorber powders are selected from among the following: B, B/sub 4/C, B/sub 2/O/ sub 3/, CaB/sub 6/, Li/sub 2/CO3, LiOH, LiBO/sub 2/, Li/s ub 2/O. The facing sheets are constructed of a neutron moderating material, so that fast neutrons will be moderated while traversing the facing sheets, and ultimately be absorbed by the absorber powder in the honeycomb. Beryllium is a preferred moderator material for use in the facing sheets. The advantage of the structure is that it combines the rigidity and light weight of a honeycomb construction with the neutron absorption properties of boron and lithium. (AEC)

Mattingly, J.T.

1962-09-25

138

Shielding and fragmentation studies.  

PubMed

Radiation dosimetry for manned spaced missions depends on the ability to adequately describe the process of high-energy ion transport through many materials. Since the types of possible nuclear interactions are many and complex, transport models are used which depend upon a reliable source of experimental data. To expand the heavy ion database used in the models we have been measuring charge-changing cross sections and fragment production cross sections from heavy-ion interactions in various elementa targets. These include materials flown on space missions such as carbon and aluminium, as well as those important in radiation dosimetry such as hydrogen, nitrogen and water. Measuring heavy-ion fragmentation through these targets also gives us the ability to determine the effectiveness of new materials proposed for shielding such as graphite composites and polyethylene hybrids. Measurement without a target present gives an indication of the level of contamination of the primary beam, which is also important in radiobiology experiments. PMID:16604611

Zeitlin, C; Guetersloh, S; Heilbronn, L; Miller, J

2005-01-01

139

Preliminary design of magnetic shielding by FEM  

SciTech Connect

In this paper, the authors propose an optimization method for magnetic shielding. The main purpose is the weight reduction of shield material. Assuming that the permeability of shield material is infinite, they simplify the magnetic shielding problem. Under this assumption, they design optimal passage for magnetic flux through the shield. They apply this method to designing the magnetic shielding for Maglev and show the effectiveness of this method by experimental and numerical data.

Sasakawa, Takashi; Tagawa, Naoto; Herai, Toshiki; Tomita, Masaru [Railway Technical Research Inst., Kokubunji, Tokyo (Japan)

1997-03-01

140

Effects of Shielding Gas on Absorption Energy of Nd-YAG Laser for Aluminium Welding  

NASA Astrophysics Data System (ADS)

Aluminium is the one of the most abundant element situated in Earth's crust and using in thousands of industrial applications. In this study spectroscopic analysis for 1mm thick aluminium plates investigated and electron temperatures were calculated with using emission spectra obtained from plasma. The relation between electron temperature and shielding gas pressure, type, pulse energy, beam focus position and flow direction were observed. With using shielding gases Ar, He, N2 at different pressures the bead widths was measured.

Mutlu, M.; Akman, E.; Demir, A.

2007-04-01

141

Earth's Seasons  

NSDL National Science Digital Library

A computer animation on the reason for the seasons. Voice-over describes the motion of Earth around the sun to show how the sun's light impacts the tilted Earth at different times of the year, causing seasonal changes.

Rochester Museum And Science Center, Strasenburgh P.

142

Edible Earth  

NSDL National Science Digital Library

In this activity, learners make a model of the solid Earth's layers that's good enough to eat! Learners use tasty foodstuffs to simulate Earth's inner core, outer core, mantle, and crust. The recipe includes ingredients for one edible Earth, but can be doubled or tripled to accommodate groups of learners. This activity requires adult supervision.

History, American M.

2011-08-20

143

Earth Flow  

NSDL National Science Digital Library

This Flash animation with accompanying audio exhibits the different stages involved in the formation of an earth flow. A step-like scarp forms along with a flowage zone at the toe of the earth flow. The sequence concludes with the stabilization of the earth flow with vegetation. Expect long loading times.

Wiley

144

Earth Calendar  

NSDL National Science Digital Library

This handout lists major events in Earth history with approximate ages (in millions of years before present). The calendar date is determined by setting midnight, January 1, to correspond with the formation of the Earth, and setting the following midnight, December 31, to correspond to the present. Thus, the entire history of the Earth is displayed as a single calendar year.

Barker, Jeffrey

145

Snowball Earth  

NSDL National Science Digital Library

Audio program from the University of Wisconsin's Earthwatch Radio discusses the notion of the entire planet covered with ice. Doug Macdougall is an earth scientist at the University of California-San Diego and author of a new book called "Frozen Earth." He says the planet-wide freeze is known as "Snowball Earth."

146

Planet Earth  

NSDL National Science Digital Library

For those interested in a global view of the weather, Planet Earth is a "real-time 3-D model of the Earth with continuously updating night shadows and clouds." Cloud images are provided by the University of Wisconsin-Madison Space Science and Engineering Center. Planet Earth is shareware with a fee of $29.95.

147

Lunar Surface Reactor Shielding Study  

SciTech Connect

A nuclear reactor system could provide power to support long term human exploration of the moon. Such a system would require shielding to protect astronauts from its emitted radiations. Shielding studies have been performed for a Gas Cooled Reactor system because it is considered to be the most suitable nuclear reactor system available for lunar exploration, based on its tolerance of oxidizing lunar regolith and its good conversion efficiency. The goals of the shielding studies were to determine a material shielding configuration that reduces the dose (rem) to the required level in order to protect astronauts, and to estimate the mass of regolith that would provide an equivalent protective effect if it were used as the shielding material. All calculations were performed using MCNPX, a Monte Carlo transport code. Lithium hydride must be kept between 600 K and 700 K to prevent excessive swelling from large amounts of gamma or neutron irradiation. The issue is that radiation damage causes separation of the lithium and the hydrogen, resulting in lithium metal and hydrogen gas. The proposed design uses a layer of B4C to reduce the combined neutron and gamma dose to below 0.5Grads before the LiH is introduced. Below 0.5Grads the swelling in LiH is small (less than about 1%) for all temperatures. This approach causes the shield to be heavier than if the B4C were replaced by LiH, but it makes the shield much more robust and reliable.

Kang, Shawn; McAlpine, William [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Lipinski, Ronald [Sandia National Laboratories, Albuquerque, NM 87185 (United States)

2006-01-20

148

Lunar Surface Reactor Shielding Study  

NASA Astrophysics Data System (ADS)

A nuclear reactor system could provide power to support long term human exploration of the moon. Such a system would require shielding to protect astronauts from its emitted radiations. Shielding studies have been performed for a Gas Cooled Reactor system because it is considered to be the most suitable nuclear reactor system available for lunar exploration, based on its tolerance of oxidizing lunar regolith and its good conversion efficiency. The goals of the shielding studies were to determine a material shielding configuration that reduces the dose (rem) to the required level in order to protect astronauts, and to estimate the mass of regolith that would provide an equivalent protective effect if it were used as the shielding material. All calculations were performed using MCNPX, a Monte Carlo transport code. Lithium hydride must be kept between 600 K and 700 K to prevent excessive swelling from large amounts of gamma or neutron irradiation. The issue is that radiation damage causes separation of the lithium and the hydrogen, resulting in lithium metal and hydrogen gas. The proposed design uses a layer of B4C to reduce the combined neutron and gamma dose to below 0.5Grads before the LiH is introduced. Below 0.5Grads the swelling in LiH is small (less than about 1%) for all temperatures. This approach causes the shield to be heavier than if the B4C were replaced by LiH, but it makes the shield much more robust and reliable.

Kang, Shawn; Lipinski, Ronald; McAlpine, William

2006-01-01

149

NEUTRON ABSORPTION AND SHIELDING DEVICE  

DOEpatents

A neutron absorption and shielding device is described which is adapted for mounting in a radiation shielding wall surrounding a radioactive area through which instrumentation leads and the like may safely pass without permitting gamma or neutron radiation to pass to the exterior. The shielding device comprises a container having at least one nonrectilinear tube or passageway means extending therethrough, which is adapted to contain instrumentation leads or the like, a layer of a substance capable of absorbing gamma rays, and a solid resinous composition adapted to attenuate fast-moving neutrons and capture slow- moving or thermal neutrons.

Axelrad, I.R.

1960-06-21

150

Project BioShield. 2003.  

National Technical Information Service (NTIS)

Many potential biological terrorism agents lack available countermeasures. President Bush proposed Project BioShield to encourage companies to develop new bioterror countermeasures. The main provisions of that proposal include: (1) relaxing procedures for...

F. Gottron

2003-01-01

151

Radiation shielding for neutron guides  

NASA Astrophysics Data System (ADS)

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.

Ersez, T.; Braoudakis, G.; Osborn, J. C.

2006-11-01

152

Ophthalmomyiasis during Operation Desert Shield.  

PubMed

A case of fly larva infestation of the eye (ophthalmomyiasis) is reported in an American soldier serving in Operation Desert Shield. Background information, prognosis, and treatment are discussed. PMID:1956540

Torok, P G; Davis, D L; Roley, E

1991-08-01

153

Shielding electronics behind composite structures  

SciTech Connect

The increasing use of composite structures and composite electronics boxes in space can result in a several-fold increase in electronics radiation total dose, as compared to using aluminum structures and aluminum electronics boxes. There are also desires to use Multi-Function Structures (MFS), where electronics are integral with composite structures (no electronics boxes). MFS approaches can result in an order of magnitude increase in radiation dose to electronics over conventional aluminum structures and boxes. The designer must either use rad-hard parts which are becoming more difficult to obtain since the end of the Cold War, increase spot shielding, use RADPAK{trademark} solutions, or add shielding to composite boxes and structures. With the increasing use of low hardness commercial parts to reduce costs, a brute force solution of adding shielding to composite boxes is frequently the lowest cost solution. Analyses, test data, and a flight experiment are described to assess these shielding options.

Spieth, B.D. [ITN Energy Systems, Wheat Ridge, CO (United States); Qassim, K.S.; Pittman, R.N. [Air Force Research Lab., Kirtland AFB, NM (United States); Russell, D.A. [Boeing Information, Space and Defense Systems, Seattle, WA (United States)

1998-12-01

154

Shields to Reduce Spray Drift  

Microsoft Academic Search

The effects of several spray-boom shield designs and ‘‘low-drift ’’ nozzles on spray drift are presented. Results are based on experiments conducted in a wind tunnel. Performances of all experimental shields were evaluated under two spray pressures (0·15 and 0·3MPa), and two air velocities (2·75 and 4·80m\\/s) in the wind tunnel. The distance to the centre of mass of the

HE Ozkan; A Miralles; C Sinfort; H Zhu

1997-01-01

155

Enhancement of EMP Shielding by Ferromagnetic Saturation  

Microsoft Academic Search

Although the subject of shielding by means of ferromagnetic materials has been investigated for almost four centuries, 1 it is not as well understood as the subject of shielding by means of nonferromagnetic materials. Many publications have dealt with magnetic shielding in both steady and time varying situations. Most of these papers are concerned with the calculations of shielding effectiveness

R. R. Ferber; F. J. Young

1970-01-01

156

Shielding techniques for communication cable - An update  

Microsoft Academic Search

Techniques of shielding against electronic interference (EI) in the frequency range 1-100 MHz are reviewed. The various sources of EI are discussed, including electrostatic induction; electromagnetic induction; magnetic induction; and electromagnetic pulse (EMP). The effectiveness of different shielding constructions is examined with respect to new FCC regulations for electromagnetic compatibility. Among the shielding constructions examined are: braids; tape shield; and

T. R. Scott; T. R. Russell

1984-01-01

157

Transient heat flux shielding using thermal metamaterials  

NASA Astrophysics Data System (ADS)

We have developed a heat shield based on a metamaterial engineering approach to shield a region from transient diffusive heat flow. The shield is designed with a multilayered structure to prescribe the appropriate spatial profile for heat capacity, density, and thermal conductivity of the effective medium. The heat shield was experimentally compared to other isotropic materials.

Narayana, Supradeep; Savo, Salvatore; Sato, Yuki

2013-05-01

158

New shielding materials for clinical electron beams  

Microsoft Academic Search

Since lead has recently been recognized as a source of environmental pollution, we have investigated new electron shielding materials that do not contain lead. We compared the shielding thicknesses of a hard plate and a sheet composed of the new materials with that of lead for electron beams. The shielding thickness was evaluated as the thickness required for shielding primary

Minoru Tajiri; Yuji Tokiya; Jun Uenishi; Masayoshi Sunaoka; Kazuhiro Watanabe

2006-01-01

159

Magnetic shielding for interplanetary spacecraft  

SciTech Connect

The protection of spacecraft crews from the radiation produced by high energy electrons, protons and heavier ions in the space environment is a major health concern on long duration missions. Conventional approaches to radiation shielding in space have relied on thicker spacecraft walls to stop the high energy charged particles and to absorb the resulting gamma and bremsstrahlung photons. The shielding concept described here uses superconducting magnets to deflect charged particles before they collide with the spacecraft, thus avoiding the production of secondary particles. A number of spacecraft configurations and sizes have been analyzed, ranging from a small ``storm cellar`` for use during solar flares to continuous shielding for space stations having a crew of 15--25. The effectiveness of the magnetic shielding has been analyzed using a Monte Carlo program with incident proton energies from 0.5 to 1000 MeV. Typically the shield deflects 35--99 percent of the incident particles, depending, of course on particle energy and magnetic field strength. Further evaluation studies have been performed to assess weight comparisons between magnetic and conventional shielding; to determine magnet current distributions which minimize the magnetic field within the spacecraft itself; and to assess the potential role of ceramic superconductors. 2 figs., 8 tabs.

Herring, J.S.; Merrill, B.J.

1991-12-01

160

Magnetic shielding for interplanetary spacecraft  

SciTech Connect

The protection of spacecraft crews from the radiation produced by high energy electrons, protons and heavier ions in the space environment is a major health concern on long duration missions. Conventional approaches to radiation shielding in space have relied on thicker spacecraft walls to stop the high energy charged particles and to absorb the resulting gamma and bremsstrahlung photons. The shielding concept described here uses superconducting magnets to deflect charged particles before they collide with the spacecraft, thus avoiding the production of secondary particles. A number of spacecraft configurations and sizes have been analyzed, ranging from a small storm cellar'' for use during solar flares to continuous shielding for space stations having a crew of 15--25. The effectiveness of the magnetic shielding has been analyzed using a Monte Carlo program with incident proton energies from 0.5 to 1000 MeV. Typically the shield deflects 35--99 percent of the incident particles, depending, of course on particle energy and magnetic field strength. Further evaluation studies have been performed to assess weight comparisons between magnetic and conventional shielding; to determine magnet current distributions which minimize the magnetic field within the spacecraft itself; and to assess the potential role of ceramic superconductors. 2 figs., 8 tabs.

Herring, J.S.; Merrill, B.J.

1991-01-01

161

Shielding requirements in helical tomotherapy  

NASA Astrophysics Data System (ADS)

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.

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

2007-08-01

162

Improving the accuracy of basin-averaged skyline shielding factors by concidering surface morphometrics  

NASA Astrophysics Data System (ADS)

The determination of basin-averaged denudation rates from cosmogenic nuclide concentrations in stream sediments depends on the surface production rate, scaling methods of cosmic ray intensities, and the correction algorithms for skyline, snow and vegetation shielding. While much work has been devoted to the calculation of skyline shielding factors (Dunne et al. 1999, Codilean 2006), the pitfalls of and potential solutions to the derivation of skyline shielding factors for large areas has never been addressed. Specifically, the resolution of common topographic datasets, 30 to 90 m, are coarse enough that significant underestimations, up to nearly 20 percent, of the shielding factor can occur. This effect is greatest in mountainous regions with high relief, i.e. exactly those landscapes which are most often studied with cosmogenic methods. By combining measurements of surface roughness from high resolution topographic data with cosmogenic ray shielding laws, we determined an empirical model for the calculation of accurate skyline shielding factors. Codilean A. 2006. Calculation of the cosmogenic nuclide production topographic shielding scaling factor for large areas using DEMs. Earth Surface Process and Landforms 31: pp. 785-794. Dunne J, Elmore D & Muzikar P. 1999. Scaling factors for the rates of production of cosmogenic nuclides for geometric shielding and attenuation at depth on sloped surfaces. Geomorphology 27: pp. 3-11.

Norton, K. P.; Vanacker, V.

2007-12-01

163

Evidence for an extensive Phanerozoic sediment cover on the Canadian and Fenno-Scandian shields  

SciTech Connect

Examination of the age and diameter of 75 terrestrial meteorite impact craters taken from platform and shield regions throughout the world suggest that both the Canadian and Fenno-Scandian Shields were covered by a sedimentary blanket during a portion of the Phanerozoic. Subsequent erosion, fostered perhaps by a combination of glacial and tectonic processes, has exposed both of these shields to reveal an anomalous distribution of craters through time. The primary evidence for sedimentary cover and subsequent erosion is in the form of a 280 Myr gap in the record of craters less than 15 km in diameter. Small craters of Cambrian, Ordovician and Silurian age are found in shield regions, suggesting either a thin or non-existent sediment cover during this period. However, there is no record of small diameter craters on either shield of Devonian, Carboniferous, Permian, Triassic, or Jurassic age (400 to 120 Myr). This 280 Myr gap suggests that the shields were protected from smaller body impacts by a sedimentary cover. In contrast, the record of impacts on platform sediments implies no such hiatus in the infall of cosmic bodies to the earth's surface between the Devonian and the Early Cretaceous. Subsequent erosion, perhaps by Early Cretaceous time, exposed the shields to further bombardment. In addition, pre-Devonian craters became exhumed. Thus, the record of impact craters suggests that the Canadian and Fenno-Scandian Shields were covered by sediments while part of Pangaea.

Laine, E.P.; Dickson, S.M.

1985-01-01

164

Numerical Approach for Computation of Electromagnetic Shielding  

NASA Astrophysics Data System (ADS)

Disturbing magnetic field (so-called magnetic smog) can be in certain areas suppressed by shielding jacket. Disturbing field is possible to be "lead away" from the shielded area with the use of jacket made of materials with high magnetic permeability (so-called passive shielding, or flux-entrapment shielding). If the disturbing field is time-variable, eddy currents are induced into electrically conductive jacket. Magnetic field generated by these eddy currents suppress the disturbing field (this is called active shielding, or lossy magnetic shielding). Both of these principles can be applied altogether (this is called combined shielding). Presented paper states numerical approach to shielding jacket design and is an introduction to following solution of a real problem of magnetic shielding when the disturbing magnetic field is space-time complicated. Effective design of the magnetic shielding should then be formulated as an optimization task.

Mayer, Daniel; Ulrych, Bohuš

2013-06-01

165

Neutronic reactor thermal shield  

DOEpatents

1. The combination with a plurality of parallel horizontal members arranged in horizontal and vertical rows, the spacing of the members in all horizontal rows being equal throughout, the spacing of the members in all vertical rows being equal throughout; of a shield for a nuclear reactor comprising two layers of rectangular blocks through which the members pass generally perpendicularly to the layers, each block in each layer having for one of the members an opening equally spaced from vertical sides of the block and located closer to the top of the block than the bottom thereof, whereby gravity tends to make each block rotate about the associated member to a position in which the vertical sides of the block are truly vertical, the openings in all the blocks of one layer having one equal spacing from the tops of the blocks, the openings in all the blocks of the other layer having one equal spacing from the tops of the blocks, which spacing is different from the corresponding spacing in the said one layer, all the blocks of both layers having the same vertical dimension or length, the blocks of both layers consisting of relatively wide blocks and relatively narrow blocks, all the narrow blocks having the same horizontal dimension or width which is less than the horizontal dimension or width of the wide blocks, which is the same throughout, each layer consisting of vertical rows of narrow blocks and wide blocks alternating with one another, each vertical row of narrow blocks of each layer being covered by a vertical row of wide blocks of the other layer which wide blocks receive the same vertical row of members as the said each vertical row of narrow blocks, whereby the rectangular perimeters of each block of each layer is completely out of register with that of each block in the other layer.

Lowe, Paul E. (Blue Ash, OH)

1976-06-15

166

NMR parameters in alkali, alkaline earth and rare earth fluorides from first principle calculations  

Microsoft Academic Search

19F isotropic chemical shifts for alkali, alkaline earth and rare earth of column 3 basic fluorides are measured and the corresponding isotropic chemical shieldings are calculated using the GIPAW method. When using PBE exchange correlation functional for the treatment of the cationic localized empty orbitals of Ca2+, Sc3+ (3d) and La3+ (4f), a correction is needed to accurately calculate 19F

Aymeric Sadoc; Monique Body; Christophe Legein; Mamata Biswal; Franck Fayon; Xavier Rocquefelte; Florent Boucher

2011-01-01

167

Dynamic Earth  

NSDL National Science Digital Library

Dynamic Earth consists of four sections and an assessment. Each section explores one aspect of the earth's structure and the movement of its tectonic plates. Simply follow the instructions on the screen to learn about the layers that make up the earth; how the continents arrived at their current locations; the constant movement of the tectonic plates; and the volcanoes, earthquakes, and other events that result from the movements of the plates. Students will view animations, read explanations, and use their mouse to drag and drop the earth's continents in their correct places, highlight features on a map, and cause earth's tectonic plates to move. At various points, students will check their knowledge by taking a quick quiz or playing a game to see how much they have learned about the Dynamic Earth. Students should read section introductions carefully, as they give a basic overview of concepts, and use the Glossary to look up definitions to unfamiliar terms.

Quinn, Ashlinn

2007-01-01

168

Earth Viewer  

NSDL National Science Digital Library

Earth Viewer was written primarily for elementary school students, and shows the daytime and nighttime portions of the Earth for any day of the year. Two views of the Earth are possible: a globe shows the planet as it would appear from space, and a map shows a flat view of the entire surface. The image can be animated or still, and set to any desired latitude and longitude.

Carlisle, Paul

169

Earth Lecture  

NSDL National Science Digital Library

This lecture is about the Earth, the planet which we know the most about, due to our ability to explore its interior as well as exterior. The lecture will compare values and processes on other planets to those on the Earth. It covers topics such as the interior, surface features and observations. It also includes a discussion of the Earth's crust, atmosphere, evolution and magnetic field. There is a quiz at the end of the lecture.

Schombert, Jim

2008-12-15

170

REACTOR SERVICE BUILDING, TRA635. CAMERA FACING NORTHWEST. BUILDING PROJECTS FROM ...  

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

REACTOR SERVICE BUILDING, TRA-635. CAMERA FACING NORTHWEST. BUILDING PROJECTS FROM AND CONNECTS TO SOUTH WALL OF MTR BUILDING. EARTH BERM SHIELDING PLUG STORAGE BUILDING IS AT RIGHT OF VIEW. INL NEGATIVE NO. 9913. Unknown Photographer, 2/23/1954 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

171

Earth Day  

NSDL National Science Digital Library

On April 22, 2005, people around the world will celebrate the 35th anniversary of Earth Day. This Topic in Depth focuses on the past and present of this significant day. From the Wisconsin Historical Society, the first two sites contain historical documents pertaining to Earth Day. The first (1) document features a May 1970 issue of The Gaylord Nelson Newsletter reporting on the first Earth Day. The second (2) document is a speech by Nelson entitled "An Environmental Agenda for the 70's." Housed in the archives of the US Environmental Protection Agency (EPA) website, the next two sites also contain historical documents. The first (3) site contains an article written by Nelson for the EPA Journal in April of 1980, entitled "Earth Day '70: What It Meant." The second (4) site contains an article written by John C. Whitaker (former Interior undersecretary in the Nixon administration) for the EPA Journal in the summer of 1998. The article is entitled "Earth Day Recollections: What It Was Like When the Movement Took Off." The (5) Earth Day Network (first mentioned in the April 4, 2003, Scout Report for Life Sciences) works "to broaden the environmental movement worldwide and to educate and mobilize people, governments, and corporations to take responsibility for a clean and healthy environment." In addition to information sections about Ongoing Programs, Current Campaigns, and News, the Earth Day Network website contains Earth Day 2005 Materials for organizers. From EarthDay.gov, Take Action In Your Classroom (6) offers links to a variety of environmental education resources. The next website, from the U.S. Army Environmental Center, presents (7) Army Earth Day; and links to information about the Army's environmental activities. The final (8) site is an Earth Day-inspired educational website (first reported on in the April 14, 1999 Scout Report for Science & Engineering) from the Wilderness Society. The site offers a collection of environmental education resources for teachers and students. [NL

172

Radiation Shielding Materials and Containers Incorporating Same  

DOEpatents

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.

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

2005-11-01

173

Radiation Shielding Materials and Containers Incorporating Same  

SciTech Connect

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.

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

2005-11-01

174

Rainbow Earth.  

ERIC Educational Resources Information Center

The environment is a great concern in the 1990s, and everyone needs to work at maintaining our planet. The 1992 Arizona State Library Reading Program, "Rainbow Earth," provides children with many techniques they can use to help the Earth. This reading program guide provides information on the following: goals, objectives, and evaluation; getting…

Arizona State Dept. of Library and Archives, Phoenix.

175

Earth tides  

SciTech Connect

Nineteen papers on gravity, tilt, and strain tides are compiled into this volume. Detailed chapters cover the calculation of the tidal forces and of the Earth's response to them, as well as actual observations of earth tides. Partial Contents: On Earth tides. The tidal forces: Tidal Forces. New Computations of the Tide-Generating Potential. Corrected Tables of Tidal Harmonics. The Theory of Tidal Deformations. Body Tides on an Elliptical, Rotating, Elastic and Oceanless Earth, Deformation of the Earth by Surface Loads. Gravimetric Tidal Loading Computed from Integrated Green's Functions. Tidal Friction in the Solid Earth. Loading Tides Versus Body Tides. Lunar Tidal Acceleration from Earth Satellite Orbit Analysis. Observations: gravity. Tidal Gravity in Britain: Tidal Loading and the Spatial Distribution of the Marine Tide. Tidal Loading along a Profile Europe-East Africa-South Asia-Australia and the Pacific Ocean. Detailed Gravity-Tide Spectrum between One and Four Cycles per Day. Observations: tilt and strain. Cavity and Topographic Effects in Tilt and Strain Measurement. Observations of Local Elastic Effects on Earth Tide Tilts and Strains.

Harrison, J.C.

1984-01-01

176

Earth Viewer  

NSDL National Science Digital Library

The representation is an enhanced image and animation of Earth from above that shows daytime and nighttime on 1/2 of the Earth at a time. The representation's viewing angle and date can be manipulated by the viewer, and the representation can be toggled between globe and map views.

Carlisle, Paul

177

Effects of bumper size on high velocity impact damage to Whipple shield  

Microsoft Academic Search

With the increasing number of space mission the impact risk on spacecraft at hypervelocity by space debris is increasing A collision with space debris can cause damage to a spacecraft in low Earth orbit For designing spacecraft protection constructions and developing advanced debris shieldsLhypervelocity impact simulation experiments on the ground and the computer simulation of hypervelocity impact is the important

Y. Ha; G. S. Guan; B. J. Pang; W. Zhang

2006-01-01

178

PLUG STORAGE BUILDING, TRA611, AWAITS SHIELDING SOIL TO BE PLACED ...  

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

PLUG STORAGE BUILDING, TRA-611, AWAITS SHIELDING SOIL TO BE PLACED OVER PLUG STORAGE TUBES. WING WALLS WILL SUPPORT EARTH FILL. MTR, PROCESS WATER BUILDING, AND WORKING RESERVOIR IN VIEW BEYOND PLUG STORAGE. CAMERA FACES NORTHEAST. INL NEGATIVE NO. 2949. Unknown Photographer, 7/30/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

179

Shielded radiation protection quantities beyond LEO  

NASA Astrophysics Data System (ADS)

The National Council on Radiation Protection and Measurements (NCRP) has recommended that the quantities used to evaluate health risk to astronauts due to radiation exposure be effective dose and gray-equivalent. The NCRP recommends that effective dose be the limiting quantity for prevention of stochastic effects. Effective dose is a measure of whole body exposure, a weighted average of dose equivalent to a number body tissues for which the NCRP has adopted tissue weighting factors recommended by the International Commission on Radiation Protection (ICRP). For deterministic effects, the NCRP has recommended that gray-equivalent be used. Gray-equivalent is evaluated for specific critical organs and is the weighted sum of absorbed dose from field components to that organ using the relative biological effectiveness (RBE) number for that field component. RBE numbers recommended by the NCRP are used. The NCRP has provided effective dose limits as well as limits for gray-equivalent to eyes, skin, and blood forming organs (BFO) for astronauts in low earth orbit (LEO). As yet, no such limits have been defined for astronaut operations beyond LEO. In this study, the radiation protection quantities, effective dose and gray-equivalent to the eyes, skin, and BFO, are calculated for several environments beyond LEO. The lunar surface and Martian environments are included. For each environment, these radiation protection quantities are calculated behind varying amounts of various types of shielding materials. The results are compared to the exposure limits for LEO, since limits have not yet been defined for interplanetary missions. The benefits of using shielding material containing hydrogen and choosing optimal mission times are discussed.

Clowdsley, M. S.; Wilson, J. W.; Kim, M. Y.; Anderson, B. M.; Nealy, J. E.

180

Recommendations for a Static Cosmic Ray Shield for Enriched Germanium Detectors  

SciTech Connect

This document provides a detailed study of cost and materials that could be used to shield the detector material of the international Tonne-scale germanium neutrinoless double-beta decay experiment from hadronic particles from cosmic ray showers at the Earth's surface. This work was motivated by the need for a shield that minimizes activation of the enriched germanium during storage; in particular, when the detector material is being worked on at the detector manufacturer's facility. This work considers two options for shielding the detector material from cosmic ray particles. One option is to use a pre-existing structure already located near the detector manufacturer, such as Canberra Industries in Meriden, Connecticut. The other option is to build a shield onsite at a detector manufacturer's site. This paper presents a cost and efficiency analysis of such construction.

Aguayo Navarrete, Estanislao; Orrell, John L.; Ankney, Austin S.; Berguson, Timothy J.

2011-09-21

181

The early phase of dielectric surface flashover in a simulated Low Earth Orbit environment  

Microsoft Academic Search

In Low Earth Orbit (LEO) the environment space plasma and UV radiation influences the surface charging and the surface flashover voltage of insulators, and thus the performance of high voltage systems. Understanding the mechanisms leading to surface flashover will make it possible to apply certain shielding techniques (e.g. electric and magnetic shielding) which can increase the dielectric flashover voltage drastically.

F. Hegeler; H. Krompholz; I. L. Hatfield; M. Kristiansen

1994-01-01

182

Large solar flare radiation shielding requirements for manned interplanetary missions.  

PubMed

As the 21st century approaches, there is an ever-increasing interest in launching manned missions to Mars. A major concern to mission planners is exposure of the flight crews to highly penetrating and damaging space radiations. Beyond the protective covering of the Earth's magnetosphere, the two main sources of these radiations are galactic cosmic rays and solar particle events. Preliminary analyses of potential exposures from galactic cosmic rays (GCR's) were presented elsewhere. In this Note, estimates of shielding thicknesses required to protect astronauts on interplanetary missions from the effects of large solar flare events are presented. The calculations use integral proton fluences for the February 1956, November 1960, and August 1972 solar particle events as inputs into the NASA Langley Research Center nucleon transport code BRYNTRN. This deterministic computer code transports primary protons and secondary protons and neutrons through any number of layers of target material of arbitrary thickness and composition. Contributions from target nucleus breakup (fragmentation) and recoil are also included. The results for each flare are presented as estimates of dose equivalent [in units of roentgen equivalent man (rem)] to the skin, eye, and bloodforming organs (BFO) behind various thicknesses of aluminum shielding. These results indicate that the February 1956 event was the most penetrating; however, the August 1972 event, the largest ever recorded, could have been mission- or life-threatening for thinly shielded (< or = 5 g/cm2) spacecraft. Also presented are estimates of the thicknesses of water shielding required to reduce the BFO dose equivalent to currently recommended astronaut exposure limits. These latter results suggest that organic polymers, similar to water, appear to be a much more desirable shielding material than aluminum. PMID:11537157

Townsend, L W; Nealy, J E; Wilson, J W; Atwell, W

183

Passive radiation shielding considerations for the proposed space elevator  

NASA Astrophysics Data System (ADS)

The Earth's natural van Allen radiation belts present a serious hazard to space travel in general, and to travel on the space elevator in particular. The average radiation level is sufficiently high that it can cause radiation sickness, and perhaps death, for humans spending more than a brief period of time in the belts without shielding. The exact dose and the level of the related hazard depends on the type or radiation, the intensity of the radiation, the length of exposure, and on any shielding introduced. For the space elevator the radiation concern is particularly critical since it passes through the most intense regions of the radiation belts. The only humans who have ever traveled through the radiation belts have been the Apollo astronauts. They received radiation doses up to approximately 1 rem over a time interval less than an hour. A vehicle climbing the space elevator travels approximately 200 times slower than the moon rockets did, which would result in an extremely high dose up to approximately 200 rem under similar conditions, in a timespan of a few days. Technological systems on the space elevator, which spend prolonged periods of time in the radiation belts, may also be affected by the high radiation levels. In this paper we will give an overview of the radiation belts in terms relevant to space elevator studies. We will then compute the expected radiation doses, and evaluate the required level of shielding. We concentrate on passive shielding using aluminum, but also look briefly at active shielding using magnetic fields. We also look at the effect of moving the space elevator anchor point and increasing the speed of the climber. Each of these mitigation mechanisms will result in a performance decrease, cost increase, and technical complications for the space elevator.

Jorgensen, A. M.; Patamia, S. E.; Gassend, B.

2007-02-01

184

Photo Induced-EMF Sensor Shield.  

National Technical Information Service (NTIS)

A photo-EMF detector including a shield to prevent a portion of the detector from illumination. The shield prevents the generation of unwanted noise-currents, thus increasing the performance of the photo-EMF detector.

G. J. Dunning M. Sokolich D. Vogel D. M. Pepper

2004-01-01

185

Shielding benchmark tests of JENDL-3.  

National Technical Information Service (NTIS)

The integral test of neutron cross sections for major shielding materials in JENDL-3 has been performed by analyzing various shielding benchmark experiments. For the fission-like neutron source problem, the following experiments are analyzed: (1) ORNL Bro...

M. Kawai A. Hasegawa K. Ueki N. Yamano K. Sasaki

1994-01-01

186

Single bumper shields based on Vectran fibers  

NASA Astrophysics Data System (ADS)

High strength fiber is a potential material for shielding from a viewpoint of strength, lightweight and flexibility. We developed a single bumper shield based on Vectran fibers, that stopped a polycarbonate projectile with 14 mm in diameter, 1 g in weight and 6.45 km/s in velocity. The thickness of this shield was 7 mm. As compared with the mesh stuffed Whipple bumper shield installed on the Japanese Experiment Module, the areal density was half and the thickness was approximately one sixteenth. The aim of our hypervelocity impact experiments was to develop a thin bumper material consisting of only Vectran fibers and to research a deployable shielding system for debris protection using the fiber material. The results indicated that the new thin shield with 7 mm in thickness has a good protection capability. The new single bumper shield may provide the basic technology for reinforcing the protection capability and reducing the weight of the shield drastically.

Tanaka, M.; Moritaka, Y.

2004-01-01

187

Magnetic Shielding for High Fields.  

National Technical Information Service (NTIS)

During the program a code was developed to predict the attenuation in a multilayer, non-linear system. This program allows modeling of shielding effectiveness for the complex case of high conductivity and high permeability layers in which the high permeab...

W. J. Biter

1996-01-01

188

Em Shielding of Building Materials.  

National Technical Information Service (NTIS)

This report covers the results of a program for measuring the shielding effectiveness (SE) of building materials. Part 1 of the report describes a number of techniques which were used to make radiated measurements of magnetic field SE from 10 Hz to 50 KHz...

C. M. Brennan C. C. Lambert C. G. Conner G. F. Roberts W. T. Flannery

1968-01-01

189

Gamma-Ray Shielding Studies.  

National Technical Information Service (NTIS)

A monoenergetic beam of gamma rays was used to study the deep penetration of 10-MeV gamma radiation in aluminum. Recently a positron annihilation system was developed at General Atomic for the purpose of making shielding measurements in the energy range f...

J. A. Lonergan E. A. Beaver J. Parez D. F. Herring

1967-01-01

190

Calibration of Shielded Net Radiometers  

Microsoft Academic Search

Net radiation is an important term because of its use in water bal- ance and other studies. Faulty data results from net radiometers that are not calibrated properly. Using the total shading method to cali- brate shielded net radiometers (NRs) results in faulty calibration coef- ficients because large negative net radiation is included in the results. The proposed partial shading

Leo J. Fritschen; Charles L. Fritschen

2007-01-01

191

Atomic polarizabilities and shielding factors  

Microsoft Academic Search

A detailed discussion is given of the methods of calculating atomic polarizabilities and shielding factors and the relationships between them are demonstrated. The formulation of the uncoupled Hartree-Fock approximation is presented and it is shown that the methods are all approximate versions of it. A more accurate procedure, the coupled Hartree-Fock approximation, is described. Comprehensive tables of dipole and quadrupole

A. Dalgarno

1962-01-01

192

Decontaminating lead bricks and shielding  

Microsoft Academic Search

Lead used for shielding is often surface contaminated with radioisotopes and is therefore a RCRA D008 mixed waste. The technology-based standard for treatment is macroencapsulation. However, decontaminating and recycling the clean lead is a more attractive solution. Los Alamos National Laboratory decontaminates material and equipment contaminated with radioisotopes. Decontaminating lead poses special problems because of the RCRA hazard classification and

Lussiez

1993-01-01

193

Decontaminating lead bricks and shielding  

Microsoft Academic Search

Lead used for shielding is often surface contaminated with radioisotopes and is therefore a RCRA D008 mixed waste. The technology-based standard for treatment is macroencapsulation. However, decontaminating and recycling the clean lead is a more attractive solution. Los Alamos National Laboratory decontaminates material and equipment contaminated with radioisotopes. Decontaminating lead poses special problems because of the RCRA hazard classification and

Lussiez

1994-01-01

194

Dynamic Earth  

NASA Video Gallery

Watch this NASA animation as it shows a coronal mass ejection from the sun pelts Venus, and then zooms in for a close-up view of Earth's winds and ocean currents. > Related story > Download high-res video

gsfcvideo

2012-06-19

195

Earth Bulletin  

NSDL National Science Digital Library

The Earth Bulletin is a series of stories that explain the science behind current environmental and atmospheric events on our planet. Content changes periodically and older stories are put into the sites archive.

196

Earth materials and earth dynamics  

SciTech Connect

In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

Bennett, K; Shankland, T. [and others

2000-11-01

197

Residents and windows. 1. Shielding of windows  

SciTech Connect

In order to assess the influence of the shielding of windows performed by occupants in residential buildings on the heat balance of the building, the shielding of 40,000 windows was determined by observation during two heating seasons. It is shown that the demand for privacy has a large effect on the degree of window-shielding. There are also indications that many occupants trying to save energy use window-shielding as one of their means to achieve this.

Lyrberg, M.D.

1983-06-01

198

Shielding and grounding in large detectors  

SciTech Connect

Prevention of electromagnetic interference (EMI), or ``noise pickup,`` is an important design aspect in large detectors in accelerator environments. Shielding effectiveness as a function of shield thickness and conductivity vs the type and frequency of the interference field is described. Noise induced in transmission lines by ground loop driven currents in the shield is evaluated and the importance of low shield resistance is emphasized. Some measures for prevention of ground loops and isolation of detector-readout systems are discussed.

Radeka, V.

1998-09-01

199

Stand-off shields for hypervelocity particles  

SciTech Connect

Stand-off hypervelocity particle shields offer potential weight savings of an order of magnitude or more over conventional homogeneous armors. Based on an earlier complete model for the design and optimization of a stand-of shield system, a more restricted model appropriate for retrofit shields is described. Procedures to minimize the shield mass are provided, and scaling laws for many of the important parameter relationships are illustrated. 6 refs., 5 figs.

Lawrence, R.J.

1989-01-01

200

Shielding Analysis of a Small Compact Space Nuclear Reactor.  

National Technical Information Service (NTIS)

The SP-100 reactor concept, currently in its developmental stage, has layered tungsten--lithium hydride shield. Studies indicate that this shield configuration is the lightest weight shield. This configuration and three other shielding concepts were analy...

L. L. Woodrow

1987-01-01

201

MATERIAL REQUIREMENTS FOR SHIELDING AGAINST SPACE RADIATIONS  

Microsoft Academic Search

A brief but general discussion of the material requirements for ; shielding against space radiations is presented. Emphasis is placed on ; describing the salient features of the space radiation attenuation problem in ; order to deduce the materials that will most likely produce minimum-weight ; shields. The shielding characteristics of the materials are described as a ; function of

Zerby

1963-01-01

202

Electromagnetic shielding of high-voltage cables  

NASA Astrophysics Data System (ADS)

The electromagnetic shielding of high-voltage (HV) cables has been studied both by numerical computations and by experiments performed in real-life practical situations. Two shield topologies have been considered, i.e. open- versus closed-shield configurations. The open-shield configuration consists of placing horizontally plates on the ground. The closed-shield configuration consists of a formed cable conduct base in which the HV cable is placed, and on which a cover is mounted. HV cables (150 kV) were studied in both experimental trials. With respect to the considered materials in the experiments, the ferromagnetic hot-rolled low-carbon material Magnetil® is used (ferromagnetic material), and its behaviour is compared to the shielding based on aluminium (conductive non-magnetic material). Briefly, the following average shielding factors (SF) are obtained with open-shield configurations: SF around 2 when using Magnetil®, SF around 4 when using aluminium. In closed-shielding configurations, a much more performant shielding behaviour is experimentally obtained, namely SF around 20 when using Magnetil®, while SF around 8 when using aluminium. The optimum shielding behaviour is thus obtained by a ferromagnetic closed shield.

de Wulf, M.; Wouters, P.; Sergeant, P.; Dupré, L.; Hoferlin, E.; Jacobs, S.; Harlet, P.

2007-09-01

203

Symmetrical Multifoil Shields for reducing Spray Drift  

Microsoft Academic Search

In this study, two symmetrical multi-foil shields were designed to minimise spray drift in both upwind and downwind travel directions. One shield was a symmetrical double foil that induced direct air assist (an air jet acting directly on the spray droplets), while the other shield was a symmetrical triple foil that induced both direct air assist and an air curtain

M. M Sidahmed; H. H Awadalla; M. A Haidar

2004-01-01

204

Active magnetic compensation composed of shielding panels.  

PubMed

Magnetically shielded rooms (MSRs) with materials of high permeability and active shield systems have been used to shield magnetic noise for biomagnetic measurements up to now. However, these techniques have various disadvantages. Therefore, we have developed a new shielding system composed of shielding panels using an active compensation technique. In this study, we evaluated the shielding performance of several unit panels attached together. Numerical and experimental approaches indicated that the shielding factor of a cubic model composed of 24 panels was 17 for uniform fields, and 7 for disturbances due to car movement. Furthermore, the compensation space is larger than that of an ordinary active system using large coils rather than panels. Moreover, the new active compensation system has the important advantage that panels of any shape can be assembled for occasional use because the unit panels are small and light. PMID:16012696

Kato, K; Yamazaki, K; Sato, T; Haga, A; Okitsu, T; Muramatsu, K; Ueda, T; Kobayashi, K; Yoshizawa, M

2004-11-30

205

New facility shield design criteria  

SciTech Connect

The purpose of the criteria presented here is to provide standard guidance for the design of nuclear radiation shields thoughout new facilities. These criteria are required to assure a consistent and integrated design that can be operated safely and economically within the DOE standards. The scope of this report is confined to the consideration of radiation shielding for contained sources. The whole body dose limit established by the DOE applies to all doses which are generally distributed throughout the trunk of the body. Therefore, where the whole body is the critical organ for an internally deposited radionuclide, the whole body dose limit applies to the sum of doses received must assure control of the concentration of radionuclides in the building atmosphere and thereby limit the dose from internal sources.

Howell, W.P.

1981-07-01

206

Shielding calculations for Inshas cyclotron  

NASA Astrophysics Data System (ADS)

Methods used in shielding calculations for the cyclotron vault and experimental rooms of Egypt's first cyclotron laboratory to be erected at the premises of the Nuclear Research Center, Atomic Energy Authority (Inshas) are discussed. Use is made of the removal diffusion theory and of the techniques presented in NCRP-51, Wall and ceiling dimensions are estimated based on radiation protection norms given in the ICRP-60 as issued in 1991.

Comsan, M. N. H.

1996-05-01

207

Regolith Biological Shield for a Lunar Outpost from High Energy Solar Protons  

NASA Astrophysics Data System (ADS)

Beyond Earth atmosphere, natural space radiation from Galactic Cosmic Rays and Solar Energetic Protons (SEPs) represents a significant hazard to both manned and robotic missions. For lunar settlements, protecting astronauts from SEPs is a key safety issue that needs to be addressed by identifying appropriate shielding materials. This paper investigates the interaction of SEPs with the lunar regolith, and quantifies the effectiveness of the regolith as a biological shield for a human habitat, compared to aluminum, presently the standard shielding material. Also calculated is the shielding thickness to reduce the dose in the habitat to those recommended by International Radiation Protection Committee and by NASA for operation on the international space station. The present calculations are for the most energetic solar event of February 1956, which included high energy protons up to 1000 MeV. Results show that the lunar regolith is as effective as aluminum for shielding lunar outposts. A large thickness of the regolith (~30 g/cm2) would be needed to reduce the dose in the habitat from high energy protons below the 30 days flight crew limit of 25 Rem (or 250 mSv) and significantly more shielding would be needed (~150 g/cm2) to reduce the dose down to the limit for radiation workers of 5 Rem (or 50 mSv).

Pham, Tai T.; El-Genk, Mohamed S.

2008-01-01

208

Regolith Biological Shield for a Lunar Outpost from High Energy Solar Protons  

SciTech Connect

Beyond Earth atmosphere, natural space radiation from Galactic Cosmic Rays and Solar Energetic Protons (SEPs) represents a significant hazard to both manned and robotic missions. For lunar settlements, protecting astronauts from SEPs is a key safety issue that needs to be addressed by identifying appropriate shielding materials. This paper investigates the interaction of SEPs with the lunar regolith, and quantifies the effectiveness of the regolith as a biological shield for a human habitat, compared to aluminum, presently the standard shielding material. Also calculated is the shielding thickness to reduce the dose in the habitat to those recommended by International Radiation Protection Committee and by NASA for operation on the international space station. The present calculations are for the most energetic solar event of February 1956, which included high energy protons up to 1000 MeV. Results show that the lunar regolith is as effective as aluminum for shielding lunar outposts. A large thickness of the regolith ({approx}30 g/cm{sup 2}) would be needed to reduce the dose in the habitat from high energy protons below the 30 days flight crew limit of 25 Rem (or 250 mSv) and significantly more shielding would be needed ({approx}150 g/cm{sup 2}) to reduce the dose down to the limit for radiation workers of 5 Rem (or 50 mSv)

Pham, Tai T.; El-Genk, Mohamed S. [Institute for Space and Nuclear Power Studies and Dept. of Chemical and Nuclear Engineering University of New Mexico, Albuquerque, NM 87131-0001 (United States)

2008-01-21

209

Development and Evaluation of the Next Generation of Meteoroid and Orbital Debris Shields  

NASA Astrophysics Data System (ADS)

Recent events such as the Chinese anti-satellite missile test in January 2007 and the collision between a Russian Cosmos satellite and US Iridium satellite in February 2009 are responsible for a rapid increase in the population of orbital debris in Low Earth Orbit (LEO). Without active debris removal strategies the debris population in key orbits will continue to increase, requiring enhanced shielding capabilities to maintain allowable penetration risks. One of the more promising developments in recent years for meteoroid and orbital debris shielding (MMOD) is the application of open cell foams. Although shielding onboard the International Space Station is the most capable ever flown, the most proficient configuration (stuffed Whipple shield) requires an additional ˜30% of the shielding mass for non-ballistic requirements (e.g. stiffeners, fasteners, etc.). Open cell foam structures provide similar mechanical performance to more traditional structural components such as honeycomb sandwich panels, as well as improved projectile fragmentation and melting as a result of repeated shocking by foam ligaments. In this paper, the preliminary results of an extensive hypervelocity impact test program on next generation MMOD shielding configurations incorporating open-cell metallic foams are reported.

Ryan, Shannon; Christiansen, Eric

2009-06-01

210

Tests of shielding effectiveness of Kevlar and Nextel onboard the International Space Station and the Foton-M3 capsule.  

PubMed

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. PMID:20364264

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

2010-04-03

211

Earth Walk  

NSDL National Science Digital Library

In this hands-on and feet-on excursion, learners take a science walk to visualize the planet's immense size and numerous structures, without the usual scale and ratio dimensions found in most textbooks. Learners also compare their body's height to a scaled-down Earth.

Muller, Eric

1995-01-01

212

Impact Earth  

NSDL National Science Digital Library

This planetarium show teaches about meteors, meteorites, asteroids, and comets. It includes results from NASA missions and about the dangers they can pose to life on Earth. It is created for full-dome theaters but can also be shown in flat version for TVs and computer monitors. Shows the effects of the Chixulub and Tungusta events, plus the Pallasite impact that resulted in the Brenham meteorite fall. Describes ways that asteroid hunters seek new objects in the Solar System, and how ground-penetrating radar is used to find meteorites that have reached the Earth's surface and ancient craters under the desert. Narrated by astronaut Tom Jones, it also discusses ways that humans might try to deflect an asteroid or comet that is on a collision course with Earth. Created for informal science venues (digital planetariums), it is also useful as ancillary material for middle school science. Created under NASA Cooperative Agreement NCC5-316 to Rice University in conjunction with the Houston Museum of Natural Science as part of the "Immersive Earth" project, part of the REASoN program.

Reiff, Patricia

2009-05-01

213

Visualizing Earth  

NSDL National Science Digital Library

The Visualizing Earth program uses the power of visualizations (pictures, maps, spatial representations) to help learners to visualize large volumes of data, perceive and understand complex concepts, create mental models of systems, and comprehend the interactions among data elements. Site materials include remote imagery (mostly Landsat and Space Shuttle images) of Earth surface features such as the Aral Sea, Salton Sea, and volcanoes around the world (Mt. Shasta, Mt Fuji, Mt. Kilimanjaro, and others). There is also a section that uses maps to describe and explain earthquake occurences in the Mammoth Lakes, California, area, and a VRML presentation that shows the relationship between the hypocenter and epicenter of an earthquake. The 'Fun stuff' section includes features about the Aral Sea and the Salton Sea, as well as 'Earth Detective', a feature on the use of remote imagery to detect fault systems, and a tutorial on the basics of geology. There is also information of the schools that participated in the Visualizing Earth program, and a page of links to other websites with related information.

214

Spaceship Earth  

NSDL National Science Digital Library

In this lesson, from Science NetLinks, students will develop an understanding of our planet as a system by designing a very-long-duration space mission in which the life-support system is patterned after that of earth.

Science Netlinks;

2002-09-10

215

Earth Structures  

NSDL National Science Digital Library

This web guide explores several natural phenomena that are constantly changing the face of the Earth. These geologic forces not only impact the physical features of our planet but ultimately affect the biosphere in a dramatic way. Historically, the changes have ranged from gradual (such as with the process of mountain building) to the spontaneous (such as with seismic events).

National Science Teachers Association (NSTA)

2005-04-01

216

Earth's Water  

NSDL National Science Digital Library

This resource provides an overview of the distribution and occurence of water on Earth. Topics include where and how much water there is, the water cycle, and how water is measured. There is also discussion of characteristics and distribution of surface water, groundwater, glaciers, and icecaps.

217

Terrestrial Background Reduction in RPM Systems by Direct Internal Shielding  

SciTech Connect

Gamma-ray detection systems that are close to the earth or other sources of background radiation often require shielding, especially when trying to detect a relatively weak source. One particular case of interest that we address in this paper is that encountered by the Radiation Portal Monitors (RPMs) systems placed at border-crossing Ports of Entry (POE). These RPM systems are used to screen for illicit radiological materials, and they are often placed in situations where terrestrial background is large. In such environments, it is desirable to consider simple physical modifications that could be implemented to reduce the effects from background radiation without affecting the flow of traffic and the normal operation of the portal. Simple modifications include adding additional shielding to the environment, either inside or outside the apparatus. Previous work [2] has shown the utility of some of these shielding configurations for increasing the Signal to Noise Ratio (SNR) of gross-counting RPMs. Because the total cost for purchasing and installing RPM systems can be quite expensive, in the range of hundreds of thousands of dollars for each cargo-screening installation, these shielding variations may offer increases in detection capability for relatively small cost. Several modifications are considered here in regard to their real-world applicability, and are meant to give a general idea of the effectiveness of the schemes used to reduce background for both gross-counting and spectroscopic detectors. These scenarios are modeled via the Monte-Carlo N-Particle (MCNP) code package [1] for ease of altering shielding configurations, as well as enacting unusual scenarios prior to prototyping in the field. The objective of this paper is to provide results representative of real modifications that could enhance the sensitivity of this, as well as the next generation of radiation detectors. The models used in this work were designed to provide the most general results for an RPM. These results are therefore presented as general guidance on what shielding configurations will be the most valuable for a generalized RPM, considered in light of their economic and geometric possibility in the real world.

Robinson, Sean M.; Ashbaker, Eric D.; Schweppe, John E.

2008-11-19

218

Heat pipe thermionic reactor shield optimization studies  

NASA Astrophysics Data System (ADS)

Shield optimization studies were conducted for a thermionic reactor, that uses heat pipes for both reactor heat removal and radiator. The radiator was placed on the opposite side of the payload to more efficiency reject the heat without affecting the LiH shadow shield. Neutron scattering off the radiator was an important consideration. The shield that was added to reduce the neutron scattering by itself became a source for scattering. By proper shield material selection, the radiator and radiator shield scattering contribution was reduced. A direct shield material selection trade study was performed, and tungsten was selected for the gamma ray shield. The direct shield mass was then optimized with respect to separation distance, using both the mass of the boom and electrical cables. A very important conclusion was that the optimum system mass depends on the boom structural criteria that is used. At a separation distance of 5 m the shield mass was calculated to be 1,445 kg. At 10 m, the shield mass drops to 700 kg; however, the additional electrical cable mass was 73 kg and the additional boom mass was 335 kg (or 67 kg/m) for a total mass of 1,108 kg. The boom minimum resonant structural frequency was 10 Hz.

Keshishan, Vahé; Dix, Terry E.

1992-01-01

219

Heat-shield design for glovebox applications.  

SciTech Connect

Heat shields can often be used in place of insulation materials as an effective means of insulating glovebox furnace vessels. If used properly, shields can accomplish two important objectives: thermal insulation of the vessel to maintain a desired process temperature and protection of the glovebox, equipment, and user. A heat-shield assembly can be described as an arrangement of thin, properly-spaced, metal sheets that reduce radiation heat transfer. The main problem encountered in the design of a heat shield assembly is choosing the number of shields. In determining the heat transfer characteristics of a heat-shield assembly, a number of factors must be taken into consideration. The glovebox or outside environment, material properties, geometry, and operating temperature all have varying effects on the expected results. A simple method, for planar-horizontal and cylindrical-vertical shields, allowing the approximation of the outermost shield temperature, the practical number of shields, and the net heat-transfer rate will be presented. Methods used in the fabrication of heat-shield assemblies will also be discussed.

Frigo, A. A.

1998-07-10

220

Earth meandering  

NASA Astrophysics Data System (ADS)

In this paper we try to put away current Global Tectonic Model to look the tectonic evolution of the earth from new point of view. Our new dynamic model is based on study of river meandering (RM) which infer new concept as Earth meandering(EM). In a universal gravitational field if we consider a clockwise spiral galaxy model rotate above Ninety East Ridge (geotectonic axis GA), this system with applying torsion field (likes geomagnetic field) in side direction from Rocky Mt. (west geotectonic pole WGP) to Tibetan plateau TP (east geotectonic pole EGP),it seems that pulled mass from WGP and pushed it in EGP due to it's rolling dynamics. According to this idea we see in topographic map that North America and Green land like a tongue pulled from Pacific mouth toward TP. Actually this system rolled or meander the earth over itself fractaly from small scale to big scale and what we see in the river meandering and Earth meandering are two faces of one coin. River transport water and sediments from high elevation to lower elevation and also in EM, mass transport from high altitude-Rocky Mt. to lower altitude Himalaya Mt. along 'S' shape geodetic line-optimum path which connect points from high altitude to lower altitude as kind of Euler Elastica(EE). These curves are responsible for mass spreading (source) and mass concentration (sink). In this regard, tiltness of earth spin axis plays an important role, 'S' are part of sigmoidal shape which formed due to intersection of Earth rolling with the Earth glob and actual feature of transform fault and river meandering. Longitudinal profile in mature rivers as a part of 'S' curve also is a kind of EE. 'S' which bound the whole earth is named S-1(S order 1) and cube corresponding to this which represent Earth fracturing in global scale named C-1(cube order 1 or side vergence cube SVC), C-1 is a biggest cycle of spiral polygon, so it is not completely closed and it has separation about diameter of C-7. Inside SVC we introduce cone vergence cube (CVC or geotectonic equator GE) which rotate 45 degree counterclockwise with respect to SVC. Every cube from big scale to small scale fractalize in order of 23 and every '8' shape from big scale to small scale also fractalize in the same order. Three dimensional and fractoscopic imagination about understanding the changing on earth is very important so we should imagine '8' as curved surface, sea floor spreading happened in maximum curvature of these surfaces. '8' formed from pair 'S' string with opposite direction. '8' oscillate in Pole-Pole and Side-Side direction and have saddle geometry with two 'U' path along perpendicular saddle (e.g. Lut/Jazmurian and Helmand/Mashkal basin in Iran actually intersection of this saddle shape with the earth surface and Iceland /Black Sea and CapeVerde/Victoria Lake are also In/Out (small scale polygon) of 'U' shape conduit which followed axial saddle of Side-'S-2' and Okhotsk Sea /Balkhash Lake followed axial saddle conduit of Pole-'S-2' actually intersection of this perpendicular conduit with surface make spot-like-lakes/volcanoes or basin. Global EM in Side-S-1 bounded compression region-TP inside and tension region-East African Rift offside).This is a interesting competing between two kinematic geometry - spherical and isometrical geometry by using the interaction of them we can analyze the earth face in past, present and future apart of the forces that cause this face. C-1 in two dimensional look like six sided big tent which speared over Tibet and main rod driven along GA. Pair S-1 curve. have seven component(fold) and six segment in between,S-7 exactly located on TP(center of S-1). Between two successive fold we have complex geology(e.g. eastern Iran and Afghanistan)mass dragged from North America and Siberian and accumulated gradually during six step in Earth Foundation(Tibet),S-7 bounded Takla Makan Desert (in smaller loop) and TP (in bigger loop) S-7 alter the earth balance and responsible for earth disturbing, another sample of 'S' curve we see around Australia and Kermadec/Tonga Trench, Aleutian ri

Asadiyan, H.; Zamani, A.

2009-04-01

221

Investigation of Lightning Rod Shielding Angle  

NASA Astrophysics Data System (ADS)

This paper studies those parameters affecting the shielding angle of the lightning rod (Franklin Rod) above very tall buildings. It was recommended that the shielding angle of the lightning rod is about 45°?60°. The downward lightning leader is modeled by using discrete line charges to consider the exponential distribution of charges through the downward leader. The voltage condition used by Rizk is used to investigate the inception of the upward lightning leader. Different air conditions (relative air density and air humidity) are considered for more practical simulation. The influences of lightning parameters and lightning rod height on the shielding angle are studied. The results shows that, lightning leader parameters, lightning rod height and ground slope have series effects on the lightning rod shielding angle. Based on the results, a lightning rod shielding angle for shielding design is recommended to decrease the lightning stroke to the lightning rod.

Nayel, Mohamed

222

Red Sea Floor Origin: Rare-Earth Evidence  

Microsoft Academic Search

Abundance patterns of rare earths of submarine tholeiitic basalts from the axial trough of the Red Sea resemble those of basalts from midocean ridges but are distinct from shield or plateau basalts of tholeiitic composition. These results imply that a similar magmatic process, related to spreading of sea floors, operates beneath the axial trough of the Red Sea and the

Jean-Guy Schilling

1969-01-01

223

VAPOR SHIELD FOR INDUCTION FURNACE  

DOEpatents

This patent relates to a water-cooled vapor shield for an inductlon furnace that will condense metallic vapors arising from the crucible and thus prevent their condensation on or near the induction coils, thereby eliminating possible corrosion or shorting out of the coils. This is accomplished by placing, about the top, of the crucible a disk, apron, and cooling jacket that separates the area of the coils from the interior of the cruclbIe and provides a cooled surface upon whlch the vapors may condense.

Reese, S.L.; Samoriga, S.A.

1958-03-11

224

Breathing Earth  

NSDL National Science Digital Library

Visual simulation and representation programs and applications have been popping up online in greater numbers, and this recent find is one that will pique the interest of scientists, policy makers, and others who are concerned about carbon dioxide emission rates across the Earth. The Breathing Earth site was created by David Bleja, and he draws on a number of resources (such as the World Factbook and the United Nations) for the data that is utilized to create this site. Visitors can scroll over different countries to learn about their population, their emissions, and their birth and death rate. This interactive map and educational resource also contains a legend in the right-hand corner which explains the various symbols in use here.

Bleja, David

225

Earth Math  

NSDL National Science Digital Library

This text explores a few of the many concepts that frequently come up in the study of Earth systems and global climate change. Students will be exposed to many problems involving unit conversion. Global climate change reports involve terms such as kilowatt-hour, megawatt-hour, and gigawatt-hour, as well as megatons and gigatons. Students will become versed in converting units where appropriate, and through the calculations, will work with the concept of significant figures. Creating linear equations from graphical and tabular information is covered, as well as forecasting. The text is meant to be used as a companion to standard Earth science and mathematics courses, and presents enough application problems to allow students to quantitatively understand typical media reports about global climate change.

2009-01-01

226

Earth Institute  

NSDL National Science Digital Library

The mission of the Earth Institute at Columbia University is to help the world achieve sustainability by expanding understanding of the Earth as one integrated system. Through research, education, and the practical application of research to real-world challenges, the Institute addresses nine interconnected global issues: climate and society, water, energy, poverty, ecosystems, public health, food and nutrition, and hazards and urbanization. The Institute's site offers a collection of videotaped events, including the biannual "State of the Planet" conferences, 2002-08, a Distinguished Lecture series, and the Sustainable Development seminar series, as well as e-seminars and e-briefings, information about funding opportunities, and information about educational opportunities at Columbia.

227

Earth Lab  

NSDL National Science Digital Library

Earth Lab is a database of fossils, minerals and rocks from the UK. A photograph is displayed for each specimen selected, as well as the scientific name, location and properties or age of the specimen. The fossils can be searched by area, age, and group; minerals by area, element, group, and property; and rocks by area, geological age, and type of rock. A series of questions allows users to identify their own specimens.

228

Earth Rocks!  

NSDL National Science Digital Library

The purpose of this lesson is to introduce students to the basic elements of our Earth's crust: rocks, soils and minerals. They learn how we categorize rocks, soils and minerals and how they are literally the foundation for our civilization. Students also explore how engineers use rocks, soils and minerals to create the buildings, roads, vehicles, electronics, chemicals, and other objects we use to enhance our lives.

Integrated Teaching And Learning Program

229

Shielding for thermoacoustic tomography with RF excitation  

NASA Astrophysics Data System (ADS)

Radiofrequency (RF) pulses used to generate thermoacoustic computerized tomography (TCT) signal couple directly into the pulser-receiver and oscilloscope, swamping true TCT signal. We use a standard RF enclosure housing both RF amplifier and object being imaged. This is similar to RF shielding of magnetic resonance imaging (MRI) suites and protects electronics outside from stray RF. Unlike MRI, TCT receivers are ultrasound transducers, which must also be shielded from RF. A transducer housing that simultaneously shields RF and permits acoustic transmission was developed specifically for TCT. We compare TCT signals measured with and without RF shielding.

Mitchell, M.; Becker, G.; Dey, P.; Generotzky, J.; Patch, S. K.

2008-03-01

230

Hot Cell Window Shielding Analysis Using MCNP  

SciTech Connect

The Idaho National Laboratory Materials and Fuels Complex nuclear facilities are undergoing a documented safety analysis upgrade. In conjunction with the upgrade effort, shielding analysis of the Fuel Conditioning Facility (FCF) hot cell windows has been conducted. This paper describes the shielding analysis methodology. Each 4-ft thick window uses nine glass slabs, an oil film between the slabs, numerous steel plates, and packed lead wool. Operations in the hot cell center on used nuclear fuel (UNF) processing. Prior to the shielding analysis, shield testing with a gamma ray source was conducted, and the windows were found to be very effective gamma shields. Despite these results, because the glass contained significant amounts of lead and little neutron absorbing material, some doubt lingered regarding the effectiveness of the windows in neutron shielding situations, such as during an accidental criticality. MCNP was selected as an analysis tool because it could model complicated geometry, and it could track gamma and neutron radiation. A bounding criticality source was developed based on the composition of the UNF. Additionally, a bounding gamma source was developed based on the fission product content of the UNF. Modeling the windows required field inspections and detailed examination of drawings and material specifications. Consistent with the shield testing results, MCNP results demonstrated that the shielding was very effective with respect to gamma radiation, and in addition, the analysis demonstrated that the shielding was also very effective during an accidental criticality.

Chad L. Pope; Wade W. Scates; J. Todd Taylor

2009-05-01

231

Accelerator magnet designs using superconducting magnetic shields  

SciTech Connect

Superconducting dipoles and quadrupoles for existing accelerators have a coil surrounded by an iron shield. The shield limits the fringe field of the magnet while having minimal effect on the field shape and providing a small enhancement of the field strength. Shields using superconducting materials can be thinner and lighter and will not experience the potential of a large de-centering force. Boundary conditions for these materials, material properties, mechanical force considerations, cryostat considerations and some possible geometrical configurations for superconducting shields will be described. 7 refs., 3 figs., 3 tabs.

Brown, B.C.

1990-10-01

232

Simulation analysis for the materials shielding effectiveness of EMP  

Microsoft Academic Search

The theory of shielding is introduced, and the simulation model is built. The software based on the CST is applied to simulate and analyze the pulse waveform. The shielding effectiveness of different pulse width is computed. Comparing the pulse shielding effectiveness with continuous wave shielding effectiveness, there is consistent result approximately. And the shielding effectiveness based on the frequency function

Long Zhang; Xiaofeng Hu; Xinfu Lu; Genchun Zhu; Yongqiang Zhang

2011-01-01

233

Magnetic Shielded Enclosure Design in the DC and VLF Region  

Microsoft Academic Search

A review of magnetic, shielding concepts and equations as applied to ideal shield configurations has provided a basis for the analysis of the shielding effectiveness of practical shielded enclosures to dc and VLF magnetic fields. The permeability of the shield material is considered as a function of the induction, and a significantly improved method of estimating the induction and permeability

Alan Thomas; ALFRED ECKERSLEY

1968-01-01

234

Decontaminating lead bricks and shielding  

SciTech Connect

Lead used for shielding is often surface contaminated with radioisotopes and is therefore a RCRA D008 mixed waste. The technology-based standard for treatment is macroencapsulation. However, decontaminating and recycling the clean lead is a more attractive solution. Los Alamos National Laboratory decontaminates material and equipment contaminated with radioisotopes. Decontaminating lead poses special problems because of the RCRA hazard classification and the size of the inventory, now about 50 tons and likely to grow substantially because of planned decommissioning operations. This lead, in the form of bricks and other shield shapes, is surface contaminated with fission products. One of the best methods for decontaminating lead is removing the thin superficial layer of contamination with an abrasive medium trader pressure. For lead, a mixture of alumina with water and air at about 40 psig rapidly and effectively decontaminates the lead. The abrasive medium is sprayed onto the lead in a sealed-off area. The slurry of abrasive and particles of lead falls through a floor grating and is collected in a sump. A pump sends the slurry mixture back to the spray gun, creating a continuous process. The process generates small volumes of contaminated lead slurry that can be solidified and, because it passes the TCLP, is not a mixed waste. The decontaminated lead can be released for recycling.

Lussiez, G.W.

1993-05-01

235

Decontaminating lead bricks and shielding  

SciTech Connect

Lead used for shielding is often surface contaminated with radioisotopes and is therefore a RCRA D008 mixed waste. The technology-based standard for treatment is macroencapsulation. However, decontaminating and recycling the clean lead is a more attractive solution. Los Alamos National Laboratory decontaminates material and equipment contaminated with radioisotopes. Decontaminating lead poses special problems because of the RCRA hazard classification and the size of the inventory, now about 50 tons and likely to grow substantially of planned decommissioning operations. Thus lead, in the form of bricks and other shield shapes, is surface contaminated with fission products. One of the best methods for contaminated lead is removing the superficial layer of contamination with an abrasive medium under pressure. For lead, a mixture of alumina with water and air at about 40 psig rapidly and effectively decontaminates the lead. The abrasive medium is sprayed onto the lead in a scaled-off area. The slurry of abrasive and particles of lead falls through a floor and is collected in a sump. A pump sends the slurry mixture back to the spray gun, creating a continuous process. The process generates small volumes of lead slurry that can be solidified and, because it passes the TCLP, is not a mixed waste. The decontaminated lead can be released for recycling.

Lussiez, G.

1994-02-01

236

THE NIOSH SHIELD HYDRAULICS INSPECTION AND EVALUATION OF LEG DATA (SHIELD) COMPUTER PROGRAM  

Microsoft Academic Search

Longwall shields provide essential ground control in longwall mining, yet a high percentage of shields are operating at less than peak capacity and many at well below the rated support capacity due to defective hydraulic cylinders or malfunctions in other hydraulic components. Leg pressure data are currently collected on state-of- the-art longwall shields, but typically are not analyzed to evaluate

David P. Conover; Senior Mine Engineer

237

Earth Structure: Layers of the Earth  

NSDL National Science Digital Library

This interactive Flash allows users to explore Earth's structure and processes that occur on Earth such as earthquakes and plate tectonics and how scientists know the composition and state of the Earth's layers. Interactive diagrams and animations with supplementary information make this a helpful overview or review for high school and undergraduate introductory-level courses in physical geology and Earth sciences.

Smoothstone; Mifflin, Houghton

238

Earth Gauge  

NSDL National Science Digital Library

Earth Gauge is a free environmental information service for broadcast meteorologists in major U.S. media markets, based on the 3-5 day forecast. The service is designed to make it easy to talk about the links between weather and the environment on-air with simple "factoids" and viewer action tips. Teachers or students can browse an index of weather conditions, environmental impacts, and viewer action tips for many locations, organized by city, weather type, or environmental topic. There are also links to additional resources, including fact sheets and special features, imagery, video clips, and others.

239

Magnetic Shielding of Exomoons beyond the Circumplanetary Habitable Edge  

NASA Astrophysics Data System (ADS)

With most planets and planetary candidates detected in the stellar habitable zone (HZ) being super-Earths and gas giants rather than Earth-like planets, we naturally wonder if their moons could be habitable. The first detection of such an exomoon has now become feasible, and due to observational biases it will be at least twice as massive as Mars. However, formation models predict that moons can hardly be as massive as Earth. Hence, a giant planet's magnetosphere could be the only possibility for such a moon to be shielded from cosmic and stellar high-energy radiation. Yet, the planetary radiation belt could also have detrimental effects on exomoon habitability. Here we synthesize models for the evolution of the magnetic environment of giant planets with thresholds from the runaway greenhouse (RG) effect to assess the habitability of exomoons. For modest eccentricities, we find that satellites around Neptune-sized planets in the center of the HZ around K dwarf stars will either be in an RG state and not be habitable, or they will be in wide orbits where they will not be affected by the planetary magnetosphere. Saturn-like planets have stronger fields, and Jupiter-like planets could coat close-in habitable moons soon after formation. Moons at distances between about 5 and 20 planetary radii from a giant planet can be habitable from an illumination and tidal heating point of view, but still the planetary magnetosphere would critically influence their habitability.

Heller, René; Zuluaga, Jorge I.

2013-10-01

240

Studies on the neutron field behind shielding of proton accelerators Part I: Concrete shielding  

NASA Astrophysics Data System (ADS)

Energy- and angular distributions of neutrons behind concrete side shielding of proton accelerators were calculated. Simple arguments are given to understand the characteristic shape of the neutron spectrum. Calculations were repeated to receive data for simple shielding estimations. The dose equivalent attenuation coefficient of concrete for monoenergetic neutrons with energies between 1 and 400 MeV were determined and compared with the coefficient for neutrons leaving an accelerator shield at angles around 90°. Data for shielding gaps in accelerator shielding walls are given as an application. The calculations were performed by using the Monte Carlo codes FLUKA92 and MORSE.

Dinter, H.; Tesch, K.; Dworak, D.

1996-01-01

241

Solar shield: forecasting and mitigating space weather effects on high-voltage power transmission systems  

Microsoft Academic Search

In this paper, central elements of the Solar Shield project, launched to design and establish an experimental system capable\\u000a of forecasting the space weather effects on high-voltage power transmission system, are described. It will be shown how Sun–Earth\\u000a system data and models hosted at the Community Coordinated Modeling Center (CCMC) are used to generate two-level magnetohydrodynamics-based\\u000a forecasts providing 1–2 day and

Antti Pulkkinen; Michael Hesse; Shahid Habib; Luke Van der Zel; Ben Damsky; Fritz Policelli; David Fugate; William Jacobs; Elizabeth Creamer

2010-01-01

242

EMP coupling to coaxial shielded cables  

Microsoft Academic Search

A method for determining the effects induced within shielded cables by a high-altitude nuclear electromagnetic pulse (EMP), represented as a plane wave, is presented. The cable is regarded as a multiconductor line in which the EMP sources are impressed on the shield. An efficient matrix procedure permits simultaneous calculation of transient voltages and currents at any point on each conductor.

M. D'Amore; M. Feliziani

1988-01-01

243

Project Desert Shield-Preschool Style.  

ERIC Educational Resources Information Center

Describes Project Desert Shield, a curriculum that preschool children and teachers at a U.S. military base in Germany developed to embrace and constructively deal with the interests and concerns of the children about Operation Desert Shield/Desert Storm through dramatic play. (Author/BB)

Suskind, Diane

1993-01-01

244

Shielding effectiveness of superconductive particles in plastics  

SciTech Connect

The ability to cool superconductors with liquid nitrogen instead of liquid helium has opened the door to a wide range of research. The well known Meissner effect, which states superconductors are perfectly diamagnetic, suggests shielding applications. One of the drawbacks to the new ceramic superconductors is the brittleness of the finished material. Because of this drawback, any application which required flexibility (e.g., wire and cable) would be impractical. Therefore, this paper presents the results of a preliminary investigation into the shielding effectiveness of YBa/sub 2/Cu/sub 3/O/sub 7-x/ both as a composite and as a monolithic material. Shielding effectiveness was measured using two separate test methods. One tested the magnetic (near field) shielding, and the other tested the electromagnetic (far field) shielding. No shielding was seen in the near field measurements on the composite samples, and only one heavily loaded sample showed some shielding in the far field. The monolithic samples showed a large amount of magnetic shielding. 5 refs., 5 figs.

Pienkowski, T.; Kincaid, J.; Lanagan, M.T.; Poeppel, R.B.; Dusek, J.T.; Shi, D.; Goretta, K.C.

1988-09-01

245

US Missile Shield Plan Heightens European Insecurities  

Microsoft Academic Search

European Missile Shield The US Missile Defence Agency (MDA) – without recourse to NATO – is engaged in bilateral negotiations with Poland and the Czech Republic to site missile-shield silos and X-Band radar facilities in central Europe. The US intends to site 10 long-range interceptor missiles at one weapon silo - approximately the size of a football pitch - in

Tom Clonan

2008-01-01

246

10 CFR 36.25 - Shielding.  

Code of Federal Regulations, 2010 CFR

...10 Energy 1 2009-01-01 2009-01-01 false Shielding. 36.25 Section 36.25 Energy NUCLEAR REGULATORY...Design and Performance Requirements for Irradiators § 36.25 Shielding. (a) The radiation dose rate in areas that...

2009-01-01

247

10 CFR 36.25 - Shielding.  

Code of Federal Regulations, 2010 CFR

...10 Energy 1 2010-01-01 2010-01-01 false Shielding. 36.25 Section 36.25 Energy NUCLEAR REGULATORY...Design and Performance Requirements for Irradiators § 36.25 Shielding. (a) The radiation dose rate in areas that...

2010-01-01

248

10 CFR 36.25 - Shielding.  

Code of Federal Regulations, 2013 CFR

...10 Energy 1 2013-01-01 2013-01-01 false Shielding. 36.25 Section 36.25 Energy NUCLEAR REGULATORY...Design and Performance Requirements for Irradiators § 36.25 Shielding. (a) The radiation dose rate in areas that...

2013-01-01

249

CASTABLE MATERIALS FOR NEUTRON SHIELDS. PART 2  

Microsoft Academic Search

The development of elastomeric materials for neutron shields is ; discussed. Numerous liquid natural, butyl, and polybutadiene rubbers, together ; with a specially synthesized boron modified, acrylic acid terpolymer were ; evaluated to determine their curing characteristics and properties pertaintng to ; neutron shields. It was determined that a polybutene extended butyl rubber ; filled with polyethylene and vulcanized using

W. M. Veroeven; J. W. McGarvey

1962-01-01

250

PATHFINDER ATOMIC POWER PLANT SHIELDING ANALYSIS  

Microsoft Academic Search

Shielding for the Pathfinder Atomic Power Plant, which incorporates a ; direct-cycle controlled-recirculation boiling-water reactor with an integral ; nuclear superheater, was designed. Information is presented on the shield ; design, dose levels for all areas of the plant, and methods of calculation. ; Major sources are the reactor complex in the reactor building, the main steam ; line, turbine,

R. J. Holl; D. W. Stephen

1962-01-01

251

Heat shielding: a task for youngsters  

Microsoft Academic Search

Heat shielding is a recently identified mechanism used by worker honey bees (Apis mellifera) to help maintain constant hive temperatures. Only workers perform this behavior; in our experiment, drones actively avoided heated hive regions. Observations of marked day-old cohorts within broodcomb regions indicate that heat shielding is performed by young bees to preferentially protect advanced stage larvae and pupae. As

Philip T. Starks; Rebecca N. Johnson; Adam J. Siegel; Meridith M. Decelleb

2005-01-01

252

30 CFR 56.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Ventilation and shielding for welding. 56.14213 Section 56.14213 Mineral Resources...Procedures § 56.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2013-07-01

253

30 CFR 57.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Ventilation and shielding for welding. 57.14213 Section 57.14213 Mineral Resources...Procedures § 57.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2013-07-01

254

GFR Sub-Assembly Shielding Design Studies  

SciTech Connect

This report presents the methodology and results for a preliminary study for Gas-Cooled Fast Reactor (GFR) subassembly fast neutron shielding configurations. The purpose of the shielding in the subassembly is to protect reactor components from fast (E>0.1 MeV) neutrons. The subassembly is modeled in MCNP version 5 release 1.30. Parametric studies were performed varying the thickness of the shielding and calculating the fast neutron flux at the vessel head and the core grid plate. This data was used to determine the minimum thickness needed to protect the vessel head and the core grid plate. These thicknesses were used to analyze different shielding configurations incorporating coolant passages and also to estimate the neutron and photon energy deposition in the shielding material.

J. R. Parry

2006-01-01

255

Shielding measurements for 230-Mev protons  

SciTech Connect

Energetic neutrons, produced as protons interact with matter, dominate the radiation shielding environment for proton accelerators. Because of the scarcity of data describing the shielding required to protect personnel from these neutrons, absorbed dose and dose-equivalent values are measured as a function of depth in a thick concrete shield at neutron emission angles of 0, 22, 45, and 90 deg for 230-MeV protons incident upon stopping-length aluminum, iron, and lead targets. Neutron attenuation lengths vary sharply with angle but are independent of the target material. Comparing results with prior shielding calculations, the High-Energy Transport Code overestimates neutron production and attenuation lengths in the forward direction. Analytical methods compare favorably in the forward direction but overestimate the production and attenuation lengths at large angles. The results presented are useful for determining the shielding requirements for proton radiotherapy facilities and as a benchmark for future calculations.

Siebers, J.V.; DeLuca, P.M. Jr.; Pearson, D.W. (Univ. of Wisconsin, Madison (United States). Dept. of Medical Physics); Coutrakon, G. (Loma Linda Univ., CA (United States). Medical Center)

1993-09-01

256

Practical radiation shielding for biomedical research  

SciTech Connect

This paper reports on calculations which exist for estimating shielding required for radioactivity; however, they are often not applicable for the radionuclides and activities common in biomedical research. A variety of commercially available Lucite shields are being marketed to the biomedical community. Their advertisements may lead laboratory workers to expect better radiation protection than these shields can provide or to assume erroneously that very weak beta emitters require extensive shielding. The authors have conducted a series of shielding experiments designed to simulate exposures from the amounts of {sup 32}P, {sup 51}Cr and {sup 125}I typically used in biomedical laboratories. For most routine work, {ge}0.64 cm of Lucite covered with various thicknesses of lead will reduce whole-body occupational exposure rates of {lt} 1mR/hr at the point of contact.

Klein, R.C.; Reginatto, M.; Party, E.; Gershey, E.L. (Rockefeller Univ., New York, NY (United States))

1990-06-01

257

ISABELLE shielding criteria and design.  

PubMed

ISABELLE is a high-intensity 400-GeV proton-storage ring under construction at Brookhaven National Laboratory (BNL). The radiation-protection problems encountered in its design are in many ways similar to those at high-energy fixed-target facilities: both the laboratory personnel nearby and the public several kilometers away must be appropriately protected from high-energy neutron and muon radiation. These radiations will result from the routine operation of the accelerators, as well as from unplanned and possibly large losses of the stored beam. The radiation exposures resulting from the loss of beam already in the accelerator could be more severe than those resulting from a full year's normal operation. The design goals (mrem/yr) which have been adopted for different populations, exposure scenarios and radiation sources are outlined. We also describe the methods (hardware, shielding, access control) which will be used to achieve these goals. PMID:6319330

Gollon, P J; Casey, W R

1984-01-01

258

Shielding calculations at dismantled synchrocyclotron  

SciTech Connect

The Space Radiation Effects Laboratory located in Newport News, Virginia, was operated by the College of William and Mary for the National Aeronautics and Space Administration. A synchrocyclotron which was formerly in operation in this building was removed in 1980. At several locations, the scattered radiation caused an induced radioactivity within the walls of the cyclotron room. A radiological survey has been performed to determine the amount of residual radioactivity on the walls. Calculations were performed to determine the thickness of the concrete walls and floor for shielding the residual radiation in the cyclotron room. Recommendations are made to minimize exposures from the residual radioactivity on the walls and floor of the cyclotron room to potential occupants working in the building. 19 refs., 1 fig., 2 tabs.

Yalcintas, M.G.

1987-01-01

259

Background simulations and shielding calculations  

SciTech Connect

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.

Kudryavtsev, Vitaly A. [Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH (United Kingdom)

2011-04-27

260

Fusion for Earth and Space  

SciTech Connect

The compact reactor concept (Williams, 2007) has the potential to provide clean, safe and unlimited supply of energy for Earth and Space applications. The concept is a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for individual home and space power. The concept also would make it possible for each plant or remote location to have it's own power source, on site, without the need for a connection to the power grid. This would minimize, or eliminate, power blackouts. The concept could replace large fission reactors and fossil fuel power plants plus provide energy for ships, locomotives, trucks and autos. It would make an ideal source of energy for space power applications and for space propulsion.

Williams, Pharis E

2009-03-16

261

Earth's Oceans  

NSDL National Science Digital Library

This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. This guide focuses on the oceans as a part of the Earth system: the link between oceans and climate; tsunamis; life science concepts such as ocean ecosystems, food webs, and biodiversity; real data â both sources of and projects that use real data; and related careers. There is also a section on the misconceptions commonly surrounding ocean concepts and finally the National Science Education Standards that these resource connect to. So even though you might not teach a unit called oceans, the oceans can be used as a context within an existing unit, such as ecosystems, energy transfer, systems thinking, or methods in science.

Lightle, Kimberly; Fries-Gaither, Jessica

2009-10-01

262

Simulation of ablation in Earth atmospheric entry  

NASA Astrophysics Data System (ADS)

The process of ablation for Earth atmospheric entry is simulated using a computational approach that allows thermo-chemical nonequilibrium of the flow field and ablation gases. The heat pulse into the heat shield is modeled. The flowfield and graphite heat shield are coupled through surface mass and energy balances. The surface thermochemistry involves the oxidation of graphite and allows for catalytic recombination of diatomic oxygen. Steady-state simulations are performed on a one meter nose radius sphere at an altitude of 65/km and at freestream velocities of 8 km/s and 10 km/s. A transient simulation is performed at 65 km altitude and a freestream velocity of 10 km/s.

Keenan, James A.; Candler, Graham V.

1993-07-01

263

Heat shields: Materials and cost considerations  

NASA Astrophysics Data System (ADS)

Heat shields reduce the operating cost of a system by intercepting radiated heat that would otherwise add to the load on the low-temperature stage of the system. While always a consideration, recent fluctuations in the cost of helium have made the use of effective heat shields all the more critical to the cost effective operation of liquid helium systems. Heat shields come in many forms; they may be completely passive; relying on a low emissivity for effective operation, or they may be actively cooled by helium vapor, an intermediate stage of a refrigerator or by liquid nitrogen. For actively cooled heat shields a high thermal conductivity as well as a low emissivity is desirable. Structural considerations, such as the need to support the cold stage of the system, as well as space limitations may also factor in to heat shield design. Heat shields have traditionally been fabricated from copper and aluminum, when the highest possible thermal conductivity is required, and to a lesser extent from stainless steel. These materials have very different mechanical properties, are assembled with different fabrication techniques and have very different installed costs. In this paper we examine heat shield design options over a range of conditions and compare the costs of different materials and design options

Seely, Mikell Lee; Bonnema, Edward; Cunningham, Eileen

2012-06-01

264

Störmer theory applied to magnetic spacecraft shielding  

NASA Astrophysics Data System (ADS)

The existence of a toroidal region from which charged particles are excluded was demonstrated by Störmer (1955) for a dipole magnetic field geometry. Using a standard numerical code to trace the trajectories of particles in a magnetic field, we find excellent agreement with the predicted region for a variety of particle energies and masses. The ability of magnetic fields to shield certain regions from energetic particles, such as galactic cosmic rays (GCRs), has led to the suggestion that certain magnetic field configurations could be used to shield the occupants of a spacecraft from the harmful effects of GCRs during interplanetary space travel. In particular, systems involving a deployed superconducting coil of wire that extends well beyond the dimensions of the spacecraft have been proposed as a viable solution to shielding GCRs. The correct use of the analysis by Störmer (1955) requires that the radius of such a coil be much smaller than the dimension of the region being shielded. Alternatively, it is shown that the energy of the particles shielded from a given region decreases as the radius of a coil with a constant magnetic moment increases. The reality is that large magnetic fields, and thus currents, are necessary to adequately shield GCRs, neither of which are provided by deployed magnetic shields.

Shepherd, S. G.; Kress, B. T.

2007-04-01

265

Determination of shielding requirements for mammography.  

PubMed

Shielding requirements for mammography when considerations are to be given to attenuation by compression paddle, breast tissue, grid and image receptor (intervening materials) has been investigated. By matching of the attenuation and hardening properties, comparisons are made between shielding afforded by breast tissue materials (water, Lucite and 50%-50% adipose-glandular tissue) and some materials considered for shielding diagnostic x-ray beams, namely lead, steel and gypsum wallboard. Results show that significant differences exist between the thickness required to produce equal attenuation and that required to produce equal hardening of a given incident beam. While attenuation equivalent thickness produces equal exposure, it does not produce equal hardening. For shielding purposes, equivalence in exposure reduction without equivalence in penetrating power of an emerging beam does not amount to equivalence in shielding affordable by two different materials. Presented are models and results of sample calculations of additional shielding requirements apart from that provided by intervening materials. The shielding requirements for the integrated beam emerging from intervening materials are different from those for the integrated beam emerging from materials (lead/steel/gypsum wallboard) with attenuation equivalent thicknesses of these intervening materials. PMID:15191311

Okunade, Akintunde Akangbe; Ademoroti, Olalekan Albert

2004-05-01

266

Integral law modeling of magnetic shields  

NASA Astrophysics Data System (ADS)

A computational tool for designing magnetic field shields is described. The tool handles electrically conducting and magnetically permeable rectangular shields. Multiple rectangular shield sub-units with orientations parallel to the three coordinate planes may be simply joined to form more complex shields. The shield geometry is discretized into rectangular elements and a current distribution is assumed for each. A system of equations consisting of the integral forms of Faraday's Law and conservation of current for electrically conducting materials, and magnetic field boundary equations at nodal points for magnetically permeable materials is built. The system of equations is simultaneously solved for values of free volume currents and magnetization surface currents at discretization points on the shield geometry. These values-taken with the assumed distribution of currents-are used to compute fields which are superimposed with the source fields at any point in space to predict the altered field levels. Results are compared with Ansoft Corporation's finite element 2D and 3D solvers, other shielding formulations, and experimentally measured data.

Gerrans, Neil Thomas

267

Integrated shielding systems for manned interplanetary spaceflight  

NASA Astrophysics Data System (ADS)

The radiation environment encountered by manned interplanetary missions can have a severe impact on both vehicle design and mission performance. This study investigates the potential impact of radiation protection on interplanetary vehicle design for a manned Mars mission. A systems approach was used to investigate the radiation protection requirements of the sum interplanetary environment. Radiation budgets were developed which result in minimum integrated shielding system masses for both nuclear and non-nuclear powered missions. A variety of system configurations and geometries were assessed over a range of dose constraints. For an annual dose equivalent rate limit of 50 rem/yr, an environmental shielding system composed of a habitat shield and storm shelter was found to result in the lowest total mass. For a limit of 65 rem/yr, a system composed of a sleeping quarters shield was least massive, and resulted in significantly reduced system mass. At a limit of 75 rem/yr, a storm shelter alone was found to be sufficient, and exhibited a further mass reduction. Optimal shielding system results for 10 MWe nuclear powered missions were found to follow along similar lines, with the addition of a reactor shadow shield. A solar minimum galactic cosmic ray spectrum and one anomalously large solar particle event during the course of a two year mission were assumed. Water was assumed for environmental radiation shielding.

George, Jeffrey A.

1992-01-01

268

Radiation shielding concrete made of Basalt aggregates.  

PubMed

In spite of the fact that Basalt is a widespread type of rock, there is very little available information on using it as aggregates for concrete radiation shielding. This paper investigates the possibility of using Basalt for the aforementioned purpose. The results have shown that Basalt could be used successfully for preparing radiation shielding concrete, but some attention should be paid to the choice of the suitable types of Basalt and for the neutron activation problem that could arise in the concrete shield. PMID:22933408

Alhajali, S; Yousef, S; Kanbour, M; Naoum, B

2012-08-29

269

Low background shielding of HPGe detector.  

PubMed

National Radiation Protection Institute in Prague is equipped with 14 HPGe detectors with relative efficiency up to 150%. Steel shielding with one of these detectors (relative efficiency 100%) was chosen to be rebuilt to decrease minimum detectable activity (MDA). Additional lead and copper shielding was built up inside the original steel shielding to reduce the volume of the inner space and filled with nitrogen by means of evaporating liquid nitrogen. MDA values decreased for Compton background up to 0.67 of original value. PMID:19243960

Trnková, L; Rulík, P

2009-01-29

270

Planetary surface reactor shielding using indigenous materials  

SciTech Connect

The exploration and development of Mars will require abundant surface power. Nuclear reactors are a low-cost, low-mass means of providing that power. A significant fraction of the nuclear power system mass is radiation shielding necessary for protecting humans and/or equipment from radiation emitted by the reactor. For planetary surface missions, it may be desirable to provide some or all of the required shielding from indigenous materials. This paper examines shielding options that utilize either purely indigenous materials or a combination of indigenous and nonindigenous materials.

Houts, Michael G.; Poston, David I.; Trellue, Holly R. [Nuclear Systems Design and Analysis Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Baca, Justin A.; Lipinski, Ronald J. [Nuclear Technology and Research, Sandia National Laboratories, Albuquerque, New Mexico 87185-1146 (United States)

1999-01-22

271

Hot cell shield plug extraction apparatus  

DOEpatents

An apparatus is provided for moving shielding plugs into and out of holes in concrete shielding walls in hot cells for handling radioactive materials without the use of external moving equipment. The apparatus provides a means whereby a shield plug is extracted from its hole and then swung approximately 90 degrees out of the way so that the hole may be accessed. The apparatus uses hinges to slide the plug in and out and to rotate it out of the way, the hinge apparatus also supporting the weight of the plug in all positions, with the load of the plug being transferred to a vertical wall by means of a bolting arrangement.

Knapp, Philip A. (Moore, ID); Manhart, Larry K. (Pingree, ID)

1995-01-01

272

Earth's Vital Signs  

NASA Website

NASA launched the Earth Observing System's flagship satellite "Terra," named for Earth, on December 18, 1999. Terra has been collecting data about Earth's changing climate. On February 24, 2000, sensors on NASA's Terra ...

273

Exploring Magnetism on Earth  

NSDL National Science Digital Library

This teacher's guide contains four lessons that provide a way for teachers to introduce students to and elaborate on Earth's changing magnetic field. It covers learning to navigate using Earth's magnetic field and compass, Earth's magnetic pole and its motion across Earth's surface, magnetic reversals on Earth, and Earth's currently declining magnetic field. These lessons have been taught primarily in math, geology, and astronomy classes.

2005-01-01

274

REPOSITORY RADIATION SHIELDING DESIGN GUIDE  

SciTech Connect

The scope of this document includes radiation safety considerations used in the design of facilities for the Yucca Mountain Site Characterization Project (YMP). The purpose of the Repository Radiation Shielding Design Guide is to document the approach used in the radiological design of the Mined Geologic Disposal System (MGDS) surface and subsurface facilities for the protection of workers, the public, and the environment. This document is intended to ensure that a common methodology is used by all groups that may be involved with Radiological Design. This document will also assist in ensuring the long term survivability of the information basis used for radiological safety design and will assist in satisfying the documentation requirements of the licensing body, the Nuclear Regulatory Commission (NRC). This design guide provides referenceable information that is current and maintained under the YMP Quality Assurance (QA) Program. Furthermore, this approach is consistent with maintaining continuity in spite of a changing design environment. This approach also serves to ensure common inter-disciplinary interpretation and application of data.

M. Haas; E.M. Fortsch

1997-09-12

275

NMR Shielding and the Periodic Table  

NASA Astrophysics Data System (ADS)

The object of this article is to find periodic, structurally significant observables that can be correlated to the nuclear shielding or alternatively to investigate whether chemical shift can be used to intensify the periodic disposition of valence electrons.

Gerothanassis, I. P.; Kalodimos, C. G.

1996-08-01

276

NMR Shielding and the Periodic Table  

Microsoft Academic Search

The object of this article is to find periodic, structurally significant observables that can be correlated to the nuclear shielding or alternatively to investigate whether chemical shift can be used to intensify the periodic disposition of valence electrons.

I. P. Gerothanassis; C. G. Kalodimos

1996-01-01

277

SP-100 low mass shield design  

SciTech Connect

The shielding considerations for an unmanned space reactor system are somewhat different from those for a terrestrial reactor. An unmanned operation in space implies that only a shadow shield, rather than a 4..pi.. one, is required to protect payload hardware that typically can tolerate 10/sup 4/ to 10/sup 6/ times more radiation than can a human crew. On the other hand, the system mass, of which the radiation shield can be a significant fraction, is a severe constraint for space reactors and not normally a problem with terrestrial ones. The object of this paper is to briefly summarize advancements made on various aspects of low mass shield design for space reactors, including materials and their arrangements, geometric factors and their potential impact on system design optimization, and proposed new configuration concepts for further mass reduction.

Carlson, D.E.

1985-01-01

278

Charge, a Space Radiation Shielding Code.  

National Technical Information Service (NTIS)

The report describes CHARGE, a FORTRAN program for the analysis of primary proton and electron passage through plane or spherical shields containing up to 100 regions, and the attendant generation and transmission of electron-induced X-rays (bremsstrahlun...

J. R. Lilley W. R. Yucker

1965-01-01

279

Shielding and Grounding Topology for Interference Control.  

National Technical Information Service (NTIS)

The topological approach to shielding and grounding is a rational and systematic method of providing the high degree of isolation required between external conductors exposed to lightning or other harsh environments and small-signal circuits susceptible t...

E. F. Vance

1977-01-01

280

Printed Wiring Board for Shielding Electromagnetic Waves.  

National Technical Information Service (NTIS)

Recently, undesired radiation of electromagnetic waves from electronic devices has become a serious problem as the signal speed is increased. For the conventional measures, circuit pattern design, selection of components, shielding, grounding and wiring h...

H. Haniu S. Kubota T. Takatsuji H. Higuchi M. Takamatsu

1989-01-01

281

Shield Design for Lunar Surface Applications  

SciTech Connect

A shielding concept for lunar surface applications of nuclear power is presented herein. The reactor, primary shield, reactor equipment and power generation module are placed in a cavity in the lunar surface. Support structure and heat rejection radiator panels are on the surface, outside the cavity. The reactor power of 1,320 kWt was sized to deliver 50 kWe from a thermoelectric power conversion subsystem. The dose rate on the surface is less than 0.6 mRem/hr at 100 meters from the reactor. Unoptimized shield mass is 1,020 kg which is much lighter than a comparable 4{pi} shield weighing in at 17,000 kg.

Johnson, Gregory A. [Pratt and Whitney -- Rocketdyne, Inc., 6633 Canoga Avenue, P.O. Box 7922 MC LA-13, Canoga Park, California 91309-7922 (United States)

2006-01-20

282

Thermal Shield and Reactor Structure Temperatures  

SciTech Connect

The purpose of this report is to present reactor structure and thermal shield temperature data taken during P-3 and P-5 cycles and compare them with design calculations in order to predict temperatures at higher power levels.

Collier, A.R.

2001-07-31

283

The Clinical Testing of Male Gonad Shields.  

National Technical Information Service (NTIS)

Two types of male gonad shields, designed for use with support garments, were tested in a number of hospitals and clinics throughout the United States. The clinical evaluation consisted of: (1) Measuring dose reduction with thermoluminescent dosimeters; a...

W. W. Church B. M. Burnett

1975-01-01

284

Low Cost Fabrication of Ablative Heat Shields.  

National Technical Information Service (NTIS)

A material and process study was performed using subscale panels in an attempt to reduce the cost of fabricating ablative heat shield panels. Although no improvements were made in the material formulation, a significant improvement was obtained in the pro...

A. M. Cecka W. C. Schofield

1972-01-01

285

Academic Earth  

NSDL National Science Digital Library

Academic Earth provides videos of lectures by top scholars in "Subjects" that range from Astronomy to Entrepreneurship to Religion, from "Universities" as celebrated as MIT, Berkeley, Harvard, and Stanford. Visitors must register to view the lectures, but registration is free. There are over 1500 video lectures available, with more being added everyday. In addition to viewing the lectures available by subject or university, visitors can choose by "Instructors" or by "Playlists". When visitors click on "Playlists" at the top of the homepage, they will see a list of lectures by theme, by several different instructors, and a grade given to the lecture series. A good example is the 6-part lecture entitled "Understanding the Financial Crisis" by four different instructors. The series is given a grade overall, in this case, an A-, and when visitors click on "See all 6 lectures" at the bottom of the series' description, they will be taken to the page with the links to the individual lectures, as well as shown the grade given each individual lecture. Visitors can even keep a playlist of their favorite lectures or download the lectures. Visitors should definitely check out the Frequently Asked Questions page, accessible by the "FAQ" link at the bottom of the website.

2009-06-09

286

Academic Earth  

NSDL National Science Digital Library

Academic Earth provides videos of lectures by top scholars in "Subjects" that range from Astronomy to Entrepreneurship to Religion, from "Universities" as celebrated as MIT, Berkeley, Harvard, and Stanford. Visitors must register to view the lectures, but registration is free. There are over 1500 video lectures available, with more being added everyday. In addition to viewing the lectures available by subject or university, visitors can choose by "Instructors" or by "Playlists". When visitors click on "Playlists" at the top of the homepage, they will see a list of lectures by theme, by several different instructors, and a grade given to the lecture series. A good example is the 6-part lecture entitled "Understanding the Financial Crisis" by four different instructors. The series is given a grade overall, in this case, an A-, and when visitors click on "See all 6 lectures" at the bottom of the series' description, they will be taken to the page with the links to the individual lectures, as well as shown the grade given each individual lecture. Visitors can even keep a playlist of their favorite lectures or download the lectures. Visitors should definitely check out the Frequently Asked Questions page, accessible by the "FAQ" link at the bottom of the website.

287

CDF forward shielding for Run II  

SciTech Connect

Detailed calculations of the accelerator related background in the CDF forward muon spectrometer have been performed with the MARS13 code and a newly developed C++ code for particle tracking in accelerator lattices. Calculated space distributions of background hits are in a good agreement with data taken in Run I. Several shielding configurations in the CDF hall and Tevatron tunnel have been studied. The optimal one provides a 30-fold shielding efficiency compatible with CDF Run II requirements.

Krivosheev, O.E.; Mokhov, N.V.

1998-03-16

288

Subsea wellhead shielding and shock mitigating system  

Microsoft Academic Search

An apparatus is described for shielding subsea well-heads from shock loads due to accidental impact due to the landing of retrieval gear. The apparatus shields the well-head from vertical impact loads by means of a generally conical outer structure and utilizes a shock-absorbing material between a portion of the outer structure and the wellhead to minimize lateral impact loads. The

G. B. Forbes; R. W. Van Houten

1976-01-01

289

Effectiveness of IC shielded packages against space radiation  

Microsoft Academic Search

This paper discusses research undertaken to evaluate and improve the effectiveness of shielded packages for protecting commercial microelectronics against ionizing dose from electrons and protons in space. The IC shielded package design data base was extended to include all important shield parameters (thickness, atomic number (Z), and edge effects). The shielding effectiveness of these packages was calculated using both forward

J. P. Spratt; B. C. Passenheim; R. E. Leadon; S. Clark; D. J. Strobel

1997-01-01

290

Design considerations for a Space Station radiation shield for protection from both man-made and natural sources  

NASA Astrophysics Data System (ADS)

This study was conducted to analyze scenarios involving the use of nuclear-power vehicles in the vicinity of a manned Space Station (SS) in low-earth-orbit (LEO) to quantify their radiological impact to the station crew. In limiting the radiant dose to crew members, mission planners may (1) shut the reactor down prior to reentry, (2) position the vehicle at a prescribed parking distance, and (3) deploy radiation shield about the shutdown reactor. The current report focuses on the third option in which point-kernel gamma-ray shielding calculations were performed for a variety of shield configurations for both nuclear electric propulsion (NEP) and nuclear thermal rocket (NTR) vehicles. For a returning NTR vehicle, calculations indicate that a 14.9 MT shield would be needed to limit the integrated crew exposure to no more than 0.05 Sv over a period of six months (25 percent of the allowable exposure to man-made radiation sources). During periods of low vehicular activity in LEO, the shield may be redeployed about the SS habitation module in order to decrease crew exposures to trapped proton radiations by approximately a factor of 10. The corresponding shield mass required for deployment at a returning NEP vehicle is 2.21 MT. Additional scenarios examined include the radioactivation of various metals as might be found in tools used in EVA activities.

Bolch, Wesley E.; Peddicord, K. Lee; Felsher, Harry; Smith, Simon

1994-12-01

291

Spallation Neutron Source Beam Dump Radiation Shielding Analysis  

SciTech Connect

Preliminary shielding calculations were performed to establish the dimensions of the radiation shielding surrounding the three Spallation Neutron Source (SNS) beam stops. Steel shielding thicknesses were sized to give dose levels of 1, 2, and 5 mrem/h at the top of the shield, and, to provide enough shielding along the sides and bottom of the beam dump so that soil activation is not a problem. It was concluded that 144 in. of steel shielding is needed above the beam stop. The thickness of the concrete floor in the service building above the dump was not a part of these calculations. This shielding design is current as of January 2000.

Johnson, J.O.

2000-02-21

292

NMR parameters in alkali, alkaline earth and rare earth fluorides from first principle calculations  

NASA Astrophysics Data System (ADS)

19F isotropic chemical shifts for alkali, alkaline earth and rare earth of column 3 basic fluorides are measured and the corresponding isotropic chemical shieldings are calculated using the GIPAW method. When using PBE exchange correlation functional for the treatment of the cationic localized empty orbitals of Ca2+, Sc3+ (3d) and La3+ (4f), a correction is needed to accurately calculate 19F chemical shieldings. We show that the correlation between experimental isotropic chemical shifts and calculated isotropic chemical shieldings established for the studied compounds allows to predict 19F NMR spectra of crystalline compounds with a relatively good accuracy. In addition, we experimentally determine the quadrupolar parameters of 25Mg in MgF2 and calculate the electric field gradient of 25Mg in MgF2 and 139La in LaF3 using both PAW and LAPW methods. The orientation of the EFG components in the crystallographic frame, provided by DFT calculations, is analysed in term of electron densities. It is shown that consideration of the quadrupolar charge deformation is essential for the analysis of slightly distorted environments or highly irregular polyhedra.

Sadoc, Aymeric; Body, Monique; Legein, Christophe; Biswal, Mamata; Fayon, Franck; Rocquefelte, Xavier; Boucher, Florent

293

Advancements in FBR shielding - Ten years in Japan  

SciTech Connect

Research and development in the area of fast breeder reactor (FBR) shielding in Japan was fully under way in April 1987 when criticality of the JOYO experimental FBR was first attained. The main activities performed and results obtained during more than 10 yr of FBR shielding research are presented. The paper describes shielding research in Joyo; Monju shielding design and related research; research activities for future FBRs; and evaluation of Monju shielding designs.

Ohtani, Nobuo; Suzuki, Soju

1990-01-01

294

Space Shielding Materials for Prometheus Application  

SciTech Connect

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 mitigate the risks in LiH development for a project with an aggressive schedule like JIMO, some background or advanced development effort for LiH should be considered for future space reactor projects.

R. Lewis

2006-01-20

295

Why Earth Science?  

ERIC Educational Resources Information Center

|This article briefly describes Earth science. The study of Earth science provides the foundation for an understanding of the Earth, its processes, its resources, and its environment. Earth science is the study of the planet in its entirety, how its lithosphere, atmosphere, hydrosphere, and biosphere work together as systems and how they affect…

Smith, Michael J.

2004-01-01

296

Earth from Above  

ERIC Educational Resources Information Center

Google Earth is a free online software that provides a virtual view of Earth. Using Google Earth, students can view Earth by hovering over features and locations they preselect or by serendipitously exploring locations that catch their fascination. Going beyond hovering, they can swoop forward and even tilt images to make more detailed…

Stahley, Tom

2006-01-01

297

Correlation between shielding effectiveness measurements and alternative methods for the characterization of shielding materials  

Microsoft Academic Search

The correlation between different methods for the characterization of shielding materials is discussed. It is found that a good agreement is obtained using basic methods, such as a four-point resistance measurement, or standard shielding effectiveness methods and using other methods allowing a quick control in the field during injection moulding process

J. A. Catrysse; M. de Goeije; W. Steenbakkers; L. Anaf

1993-01-01

298

LPT. Shield test facility (TAN645 and 646). Calibration lab shield ...  

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

LPT. Shield test facility (TAN-645 and -646). Calibration lab shield door. Ralph M. Parsons 1229-17 ANP/GE-6-645-MS-1. April 1957. Approved by INEEL Classification Office for public release. INEEL index code no. 037-0645-40-693-107369 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

299

Exploring Earth from Space  

NSDL National Science Digital Library

This set of lithographs from the ISS EarthKAM program contains an educators' guide, student information and worksheets, and several Earth photos taken from the Space Shuttle. Shuttle astronauts and the ISS EarthKAM program provide photos of our planet from the unique perspective of Earth orbit. This resource can enhance students' studies of Earth and space science, geography, social studies, mathematics, and educational technologies.

2002-12-01

300

Role of Fractals in Solid Earth Geophysics  

NASA Astrophysics Data System (ADS)

Various studies carried out across the globe reveal that many of the Earth's processes satisfy fractal statistics, where examples range from the frequency-size statistics of earthquakes to the time series of the Earth's magnetic field. The scaling property of fractal signal is very much appealing for descriptions of many geological features. It is observed from the German Continental Deep Drilling Programme (KTB) and many other deep bore wells around the world that the source distribution of density, magnetic susceptibility, electrical conductivity, acoustic impedance etc. follows power-law, hence they are fractal in nature. This finding has been incorporated in various geophysical techniques to better understand the non-linear processes in Earth systems. Theoretical relation between source and potential fields is established and based on that techniques for gravity and magnetic interpretation methods have been reformulated. A new scaling power spectral method is developed to understand source behaviour and parameters of the Earth's interior. Further, fractal concept of tessellation has been used to model the complex geometrical object, which was hitherto unaddressed. An entirely new technique has been proposed to generate the complex geometrical structures with desired physical property variation for forward and inverse modeling of the geophysical data. Further, the concept of fractal distribution of frequency and magnitude of earthquakes is exploited in aftershock study of the major earthquakes such as, Uttarkashi (1991), Latur (1993), Jabalpur (1997), Chamoli (1999), Bhuj (2001) and Muzzafarabad (2005). This study revealed that the Himalayan earthquakes follow multifractal distribution however, shield earthquakes follow monofractal distribution. This finding has been used to explain the earthquake mechanism in Himalayan and shield areas. The fractal study was extended to sea earthquakes and wave propagation modeling is done to understand the effect of Tsunami generating earthquakes from Makran and Sumatra subduction zones in Arabian Sea and Bay of Bengal respectively of Indian Ocean.

Dimri, V. P.

2007-12-01

301

Hydrogen Induced Cracking of Drip Shield  

SciTech Connect

One potential failure mechanism for titanium and its alloys under repository conditions is via the absorption of atomic hydrogen in the metal crystal lattice. The resulting decreased ductility and fracture toughness may lead to brittle mechanical fracture called hydrogen-induced cracking (HIC) or hydrogen embrittlement. For the current design of the engineered barrier without backfill, HIC may be a problem since the titanium drip shield can be galvanically coupled to rock bolts (or wire mesh), which may fall onto the drip shield, thereby creating conditions for hydrogen production by electrochemical reaction. The purpose of this scientific analysis and modeling activity is to evaluate whether the drip shield will fail by HIC or not under repository conditions within 10,000 years of emplacement. This Analysis and Model Report (AMR) addresses features, events, and processes related to hydrogen induced cracking of the drip shield. REV 00 of this AMR served as a feed to ''Waste Package Degradation Process Model Report'' and was developed in accordance with the activity section ''Hydrogen Induced Cracking of Drip Shield'' of the development plan entitled ''Analysis and Model Reports to Support Waste Package PMR'' (CRWMS M&O 1999a). This AMR, prepared according to ''Technical Work Plan for: Waste Package Materials Data Analyses and Modeling'' (BSC 2002), is to feed the License Application.

G. De

2003-02-24

302

MEANS FOR SHIELDING AND COOLING REACTORS  

DOEpatents

Reactors of the water-cooled type and a means for shielding such a rcactor to protect operating personnel from harmful radiation are discussed. In this reactor coolant tubes which contain the fissionable material extend vertically through a mass of moderator. Liquid coolant enters through the bottom of the coolant tubes and passes upwardly over the fissionable material. A shield tank is disposed over the top of the reactor and communicates through its bottom with the upper end of the coolant tubes. A hydrocarbon shielding fluid floats on the coolant within the shield tank. With this arrangements the upper face of the reactor can be opened to the atmosphere through the two superimposed liquid layers. A principal feature of the invention is that in the event radioactive fission products enter thc coolant stream. imposed layer of hydrocarbon reduces the intense radioactivity introduced into the layer over the reactors and permits removal of the offending fuel material by personnel shielded by the uncontaminated hydrocarbon layer.

Wigner, E.P.; Ohlinger, L.A.; Young, G.J.; Weinberg, A.M.

1959-02-10

303

Advances in space radiation shielding codes.  

PubMed

Early space radiation shield code development relied on Monte Carlo methods and made important contributions to the space program. Monte Carlo methods have resorted to restricted one-dimensional problems leading to imperfect representation of appropriate boundary conditions. Even so, intensive computational requirements resulted and shield evaluation was made near the end of the design process. Resolving shielding issues usually had a negative impact on the design. Improved spacecraft shield design requires early entry of radiation constraints into the design process to maximize performance and minimize costs. As a result, we have been investigating high-speed computational procedures to allow shield analysis from the preliminary concept to the final design. For the last few decades, we have pursued deterministic solutions of the Boltzmann equation allowing field mapping within the International Space Station (ISS) in tens of minutes using standard Finite Element Method (FEM) geometry common to engineering design methods. A single ray trace in such geometry requires 14 milliseconds and limits application of Monte Carlo methods to such engineering models. A potential means of improving the Monte Carlo efficiency in coupling to spacecraft geometry is given. PMID:12793737

Wilson, John W; Tripathi, Ram K; Qualls, Garry D; Cucinotta, Francis A; Prael, Richard E; Norbury, John W; Heinbockel, John H; Tweed, John; De Angelis, Giovanni

2002-12-01

304

Neutron Detector Shielding Using Boron and Water  

NASA Astrophysics Data System (ADS)

There has always been a need to develop better shielding for particle detectors from background radiation. With the development of DUSEL (Deep Underground Science and Engineering Laboratory at Homestake), new opportunities exist to make measurements away from the surface cosmic radiation. Doing measurements underground, coupled with better shielding, allows measurements of reactions that are too weak to observe otherwise. Underground, we can take advantage of thousands of meters of rock to shield detectors from cosmic background radiation. Even this rock can be insufficient, as a naturally occurring radioisotopes found in the rock can yield many kinds of radiation, such as gamma rays, beta rays, alpha particles, neutrons, and other fission products. We are designing and testing a shield made for our proportional neutron detectors made of boron and water. Water is used to slow down, or thermalize, the neutrons. Boron is in turn used to capture the incoming neutrons, due to its large neutron capture cross section. This shield was tested and the data has been analyzed, showing that we can achieve a factor of 63 reduction in the number of neutrons detected. We will also scale down this design so that it can provide background protection to detectors in the Nuclear Structure Laboratory at the University of Notre Dame.

Jung, Frederick; Best, Andreas; Aprahamian, Ani; Wiescher, Michael

2010-11-01

305

Measurement of 56Fe activity produced in inelastic scattering of neutrons created by cosmic muons in an iron shield.  

PubMed

We report on the study of the intensities of several gamma lines emitted after the inelastic scattering of neutrons in (56)Fe. Neutrons were produced via nuclear processes induced by cosmic muons in the 20tons massive iron cube placed at the Earth's surface and used as a passive shield for the HPGe detector. Relative intensities of detected gamma lines are compared with the results collected in the same iron shield by the use of the (252)Cf neutrons. Assessment against the published data from neutron scattering experiments at energies up to 14MeV is also provided. It allowed us to infer the qualitative information about the average energy of muon-created neutrons in the iron shield. PMID:21890368

Krmar, M; Jovan?evi?, N; Nikoli?, D

2011-08-22

306

DNA fragmentation induced by Fe ions in human cells: shielding influence on spatially correlated damage.  

PubMed

Outside the magnetic field of the Earth, high energy heavy ions constitute a relevant part of the biologically significant dose to astronauts during the very long travels through space. The typical pattern of energy deposition in the matter by heavy ions on the microscopic scale is believed to produce spatially correlated damage in the DNA which is critical for radiobiological effects. We have investigated the influence of a lucite shielding on the initial production of very small DNA fragments in human fibroblasts irradiated with 1 GeV/u iron (Fe) ions. We also used gamma rays as reference radiation. Our results show: (1) a lower effect per incident ion when the shielding is used; (2) an higher DNA Double Strand Breaks (DSB) induction by Fe ions than by gamma rays in the size range 1-23 kbp; (3) a non-random DNA DSB induction by Fe ions. PMID:15880923

Antonelli, F; Belli, M; Campa, A; Chatterjee, A; Dini, V; Esposito, G; Rydberg, B; Simone, G; Tabocchini, M A

2004-01-01

307

Optimization of Martian regolith and ultra-high molecular weight polyethylene composites for radiation shielding and habitat structures  

NASA Astrophysics Data System (ADS)

In preparation for long duration missions to the moon, Mars or, even near earth asteroids, one challenge, amongst many others, that the space program faces is shielding against space radiation. It is difficult to effectively shield all sources of space radiation because of the broad range of types and high energies found in space, so the most important goal is to minimize the damaging effects that may occur to humans and electronics during long duration space flight. For a long duration planetary habitat, a shielding option is to use in situ resources such as the native regolith. A possible way to utilize regolith on a planet is to combine it with a binder to form a structural material that also exhibits desirable shielding properties. In our studies, we explore Martian regolith and ultra-high molecular weight polyethylene (UHMWPE) composites. We selected UHMWPE as the binder in our composites due to its high hydrogen content; a desirable characteristic for shielding materials in a space environment. Our initial work has focused on the process of developing the right ratio of simulated Martian regolith and UHMWPE to yield the best results in material endurance and strength, while retaining good shielding characteristics. Another factor in our optimization process is to determine the composite ratio that minimizes the amount of ex situ UHMWPE while retaining desirable structural and shielding properties. This consideration seeks to minimize mission weight and costs. Mechanical properties such as tensile strength of the Martian regolith/UHMWPE composite as a function of its grain size, processing parameters, and different temperature variations used are discussed. The radiation shielding effectiveness of loose mixtures of Martian regolith/ UHMWPE is evaluated using a 200 MeV proton beam and a tissue equivalent proportional counter. Preliminary results show that composites with an 80/20 ratio percent weight of regolith to UHMWPE can be fabricated with potentially useful structural strength. I n addition, Martian regolith, while not as efficient as polyethylene at reducing proton energy as a function of shield thickness, compares well with polyethylene at shielding the 200 MeV protons. These preliminary results indicate that native Martian regolith has promising properties as a habitat material for future human missions. Future work studying the shielding effectiveness and radiation tolerance will also be discussed.

Wilkins, Richard; Gersey, Brad; Baburaj, Abhijit; Barnett, Milan; Zhou, Xianren

2012-07-01

308

Slipforming of reinforced concrete shield building  

SciTech Connect

The unique design and construction features of slipforming the heavily reinforced concrete cylindrical shield walls at the Satsop nuclear plant in Washington, D.C. site are presented. The shield walls were designed in compliance with seismic requirements which resulted in the need for reinforcing steel averaging 326 kg/m/sup 3/. A 7.6 m high, three-deck moving platform was designed to permit easy installation of the reinforcing steel, embedments, and blockouts, and to facilitate concrete placement and finishing. Two circular box trusses, one on each side of the shield wall, were used in combination with a spider truss to meet both the tolerance and strength requirements for the slipform assembly.

Hsieh, M.C.; King, J.R.

1982-03-01

309

Fermilab booster beam collimation and shielding  

SciTech Connect

The beam power in the upgraded Booster at 8 GeV and 10 Hz will be 64 kW. Beam loss can result in high radiation loads in the ring. The purpose of a new beam halo cleaning system is to localize proton losses in specially shielded regions. Calculations show that this 2-stage collimation system will localize about 99% of beam loss in straight sections 6 and 7 and immediately downstream. Beam loss in the rest of the machine will be on average 0.1W/m. Local shielding will provide tolerable prompt and residual radiation levels in the tunnel, above the tunnel at the surface and in the sump water. Results of thorough MARS calculations are presented for a new design which includes shielding integrated with the collimators, motors and controls ensuring a high performance and facilitating maintenance. First measurements of the collimation efficiency are presented.

Nikolai V. Mokhov et al.

2003-05-28

310

First Wall, Blanket, Shield Engineering Technology Program  

SciTech Connect

The First Wall/Blanket/Shield Engineering Technology Program sponsored by the Office of Fusion Energy of DOE has the overall objective of providing engineering data that will define performance parameters for nuclear systems in advanced fusion reactors. The program comprises testing and the development of computational tools in four areas: (1) thermomechanical and thermal-hydraulic performance of first-wall component facsimiles with emphasis on surface heat loads; (2) thermomechanical and thermal-hydraulic performance of blanket and shield component facsimiles with emphasis on bulk heating; (3) electromagnetic effects in first wall, blanket, and shield component facsimiles with emphasis on transient field penetration and eddy-current effects; (4) assembly, maintenance and repair with emphasis on remote-handling techniques. This paper will focus on elements 2 and 4 above and, in keeping with the conference participation from both fusion and fission programs, will emphasize potential interfaces between fusion technology and experience in the fission industry.

Nygren, R.E.

1982-01-01

311

Static Structural Analysis for a Neutron Shielding Block in ITER  

NASA Astrophysics Data System (ADS)

The ITER neutron shielding blocks are located between the outer shell and the inner shell of the vacuum vessel to provide neutron shielding. Considering the combined loads acting on the shielding blocks during ITER plasma operation, the structure of the shielding blocks must be evaluated. Using the finite element method with ANSYS analysis software, static structural analysis is performed, including elastic analysis and limit analysis for one typical shielding block. The evaluated results based on RCC-MR code show that the structure of this shielding block can meet the design requirement.

Hao, Junchuan; Song, Yuntao; Wang, Xiaoyu; Ioki, K.; Du, Shuangsong; Ji, Xiang; Feng, Changle; Xu, Yang

2013-02-01

312

Scale-PC shielding analysis sequences  

SciTech Connect

The SCALE computational system is a modular code system for analyses of nuclear fuel facility and package designs. With the release of SCALE-PC Version 4.3, the radiation shielding analysis community now has the capability to execute the SCALE shielding analysis sequences contained in the control modules SAS1, SAS2, SAS3, and SAS4 on a MS- DOS personal computer (PC). In addition, SCALE-PC includes two new sequences, QADS and ORIGEN-ARP. The capabilities of each sequence are presented, along with example applications.

Bowman, S.M.

1996-05-01

313

WASTE HANDLING BUILDING SHIELD WALL ANALYSIS  

SciTech Connect

The scope of this analysis is to estimate the shielding wall, ceiling or equivalent door thicknesses that will be required in the Waste Handling Building to maintain the radiation doses to personnel within acceptable limits. The shielding thickness calculated is the minimum required to meet administrative limits, and not necessarily what will be recommended for the final design. The preliminary evaluations will identify the areas which have the greatest impact on mechanical and facility design concepts. The objective is to provide the design teams with the necessary information to assure an efficient and effective design.

D. Padula

2000-01-13

314

The Interaction of Debye-Shielded Particles  

SciTech Connect

Macroscopic particles or solid surfaces in contact with a typical low-temperature plasma immediately charge negatively and surround themselves with an electron-depleted region of positive charge. This Debye shielding effect is involved in the Debye-Huckel theory in liquids and plasma sheath formation in the gas phase. In this report, the interaction between such screened particles is found by using the same basic approximation that is used in constructing the Debye shielding potential itself. The results demonstrate that a significant attraction exists between the particles, and, if conditions are right, this attractive force can contribute to the generation of particulate plasma crystals.

Buss, Richard J.; Riley, Merle E.

1999-04-01

315

Blue Cross and Blue Shield of Alabama  

NSDL National Science Digital Library

The Alabama BlueCross and BlueShield Medical Information Server, located and developed by the University of Alabama at Birmingham Department of Computer and Information Sciences, through a grant from Blue Cross and Blue Shield of Alabama for the express purpose of providing Internet access to medical information for all physicians and other health care providers in the state of Alabama. It provides links to a broad range of medical information resources located throughout the Internet. Menus provide information on diseases and disorders, patient care and medical practice, medical specialties, journals and newsletters, health care reform, and other medical information.

1997-01-01

316

Radiation shielding issues on the FMIT  

SciTech Connect

The Fusion Materials Irradiation Test Facility (FMIT) is being built to study neutron radiation effects in candidate fusion reactor materials. The FMIT will yield high fluence data in a fusion-like neutron radiation environment produced by the interaction of a 0.1A, 35 MeV deuteron beam with a flowing lithium target. The design of the facility as a whole is driven by a high availability requirement. The variety of radiation environments in the facility requires the use of diverse and extensive shielding. Shielding design throughout the FMIT must accommodate the need for maintenance and operations access while providing adequate personnel and equipment protection.

Burke, R.J.; Davis, A.A.; Huang, S.; Morford, R.J.

1981-05-01

317

THE STUDY ON THE INFLUENCE TO THE GROUND BY SHIELD TUNNELING CONSIDERING UPHEAVAL AND SUBSIDANCE LIMIT PRESSURE  

NASA Astrophysics Data System (ADS)

We observed upheavals of the earth's surface during excavating the tunnel at shallow overburden ground with the cast-in-place lining method. But remarkable upheavals have not been generally observed on the same situation with the shield tunneling method. The present paper examined the difference between two tunneling methods by keeping our eyes to the consolidating time of grout materials. We definited the influence range and considered that shear stresses don't work only on 2 side walls but also on 4 walls in the Terzaghi's earth pressure and calculated subsidence and upheaval limit pressure. Furthermore, We studied the correlation between the ground deformation and the influence range.

Chishiro, Keizo; Iura, Tomomi; Salto, Jun

318

Lithospheric sources of magnetic anomalies of the Aldan shield and Alpha Ridge  

NASA Astrophysics Data System (ADS)

Regional anomaly Aldan Shield is dated to ancient greenstone belt of the earth's crust. Belt is characterized by high depth forming sequences. Rocks of the upper and middle part of the section contain ferruginous quartzite. Geomagnetic and density sections allowed to estimate the power density and magnetic crustal heterogeneities. The methodology of constructing the cuts is the spectral-spatial representation of the fields, convertible into the underlying magnetic and density cuts. According to satellite data confirms the presence of regional anomalies within the Aldan shield, at an altitude of 100 km, it is about 100 nT. The presence of the Central Aldan crast-mantle fault depth of 50-80 km defines metallogenic situation of the region. The structure of the Aldan Shield detects rotational structure. Regional magnetic anomalies arc tangent frame Central Aldan region. May suggest that such behavior of anomalies is caused by of the ancient (Pre-Cambrian) fireplace mantle (the nucleus). Studies have shown that lithospheric sources Aldan shield on satellite magnetic anomalies and magnetic anomalies (?T) a Russia are located at depths of 30 to 35 and 40 to 70 km. They are confined to vertical zone deconsolidated at depths of about 30 and 40 - 70 km. By magnetic anomalies (?T) a Russian in the crust of the Aldan shield a depth of 15 - 17 km and 25 - 30 km depth revealed magnetite zone, the formation of which is due to the processes of regional metamorphism of ancient crust. Studies have shown the limits of the depth distribution of magnetite zones, mosaic developed within the crust of the Aldan shield after repeated activation of the processes of regional metamorphism.Alpha Ridge in the Arctic Ocean is one of the largest igneous provinces in the world. Tectonic history of the Arctic while not significantly deciphered. Deep structure of the Earth's crust are poorly understood Linearly elongated magnetic anomalies Alpha Ridge clearly seen at the height of the satellite. At an altitude of 100 km reach values of 100 - 120 nT, with gravity anomalies in the reduction of Faye in the central part is only 0 - 20 mg, to the periphery of the ridge rising to values of 40-50 mg. The maximum values of the magnetic anomalies are confined to the Alpha Ridge of the span latitudes 84 - 85N.Deep density and magnetic sections along the latitudinal profiles by satellite measurements showed the following. Lithospheric sources of satellite magnetic anomalies Alpha Ridge located at a depth of about 40 km and are confined to vertical zone centered deconsolidated at depths 30 - 40 km. Higher in the section allocated powerful lens decompressed at a depth of 9 - 18 km.

Litvinova, Tamara; Petrova, Alevtina

2013-04-01

319

ALTEA-SHIELD: a survey of the radiation in the ISS (USLab)  

NASA Astrophysics Data System (ADS)

In general, radiation exposure represents one of the greatest risks to humans traveling on exploration missions beyond low Earth orbit (LEO). The ALTEA detector (ALTEA-Shield experiment) is used to measure the radiation environment in different places of the ISS-USLab. ALTEA-Shield is part of the ALTEA program, a multidisciplinary research project which aims at obtaining a better understanding of the radiation environment on board the International Space Station, and also at studying the interaction between cosmic rays and the astronauts visual system. The ALTEA-Shield/Survey experiment, financed by the Italian Space Agency (ASI) and sponsored by ESA, uses the six particle detectors (SDUs, Silicon Detector Units) of ALTEA arranged on a 3D isotropic support. It is capable to measure cosmic ray particles coming from three different directions, being able to give an overview on the particle fluxes (in a detectable energy range between 3 and 900 keV/um) in different locations of the USLab. The ALTEA-Shield/Survey experiment started on September 2010 and it was placed in four locations of the USLab, resulting in a total observation time of more than 290 days. We present here the particle fluxes in the four positions, together with previous measurements acquired under the ALTEA-DOSI experimental sessions in 2006-2009; ALTEA is able to discriminate ion species (charge Z) from Z>4 and to measure the trajectory of each particle, so to be able to reconstruct the radiation flux in the three direction XYZ. The differences in the flux measured along these directions (along the ISS main body and two transverse directions) are mostly due to the different amount and quality of shielding materials passed by the incoming nuclei.

Zaconte, Veronica; Di Fino, Luca; Larosa, Marianna; Picozza, Piergiorgio; Narici, Livio; Casolino, Marco

2012-07-01

320

Earth on the Move.  

ERIC Educational Resources Information Center

|Provides background information on the layers of the earth, the relationship between changes on the surface of the earth and its insides, and plate tectonics. Teaching activities are included, with some containing reproducible worksheets and handouts to accompany them. (TW)|

Naturescope, 1987

1987-01-01

321

Implementation of ALARA radiation protection on the ISS through polyethylene shielding augmentation of the Service Module Crew Quarters.  

PubMed

With 5-7 month long duration missions at 51.6 degrees inclination in Low Earth Orbit, the ionizing radiation levels to which International Space Station (ISS) crewmembers are exposed will be the highest planned occupational exposures in the world. Even with the expectation that regulatory dose limits will not be exceeded during a single tour of duty aboard the ISS, the "as low as reasonably achievable" (ALARA) precept requires that radiological risks be minimized when possible through a dose optimization process. Judicious placement of efficient shielding materials in locations where crewmembers sleep, rest, or work is an important means for implementing ALARA for spaceflight. Polyethylene (CnHn) is a relatively inexpensive, stable, and, with a low atomic number, an effective shielding material that has been certified for use aboard the ISS. Several designs for placement of slabs or walls of polyethylene have been evaluated for radiation exposure reduction in the Crew Quarters (CQ) of the Zvezda (Star) Service Module. Optimization of shield designs relies on accurate characterization of the expected primary and secondary particle environment and modeling of the predicted radiobiological responses of critical organs and tissues. Results of the studies shown herein indicate that 20% or more reduction in equivalent dose to the CQ occupant is achievable. These results suggest that shielding design and risk analysis are necessary measures for reducing long-term radiological risks to ISS inhabitants and for meeting legal ALARA requirements. Verification of shield concepts requires results from specific designs to be compared with onboard dosimetry. PMID:15880921

Shavers, M R; Zapp, N; Barber, R E; Wilson, J W; Qualls, G; Toupes, L; Ramsey, S; Vinci, V; Smith, G; Cucinotta, F A

2004-01-01

322

Implementation of ALARA radiation protection on the ISS through polyethylene shielding augmentation of the Service Module Crew Quarters  

NASA Astrophysics Data System (ADS)

With 5-7 month long duration missions at 51.6° inclination in Low Earth Orbit, the ionizing radiation levels to which International Space Station (ISS) crewmembers are exposed will be the highest planned occupational exposures in the world. Even with the expectation that regulatory dose limits will not be exceeded during a single tour of duty aboard the ISS, the "as low as reasonably achievable" (ALARA) precept requires that radiological risks be minimized when possible through a dose optimization process. Judicious placement of efficient shielding materials in locations where crewmembers sleep, rest, or work is an important means for implementing ALARA for spaceflight. Polyethylene (C nH n) is a relatively inexpensive, stable, and, with a low atomic number, an effective shielding material that has been certified for use aboard the ISS. Several designs for placement of slabs or walls of polyethylene have been evaluated for radiation exposure reduction in the Crew Quarters (CQ) of the Zvezda (Star) Service Module. Optimization of shield designs relies on accurate characterization of the expected primary and secondary particle environment and modeling of the predicted radiobiological responses of critical organs and tissues. Results of the studies shown herein indicate that 20% or more reduction in equivalent dose to the CQ occupant is achievable. These results suggest that shielding design and risk analysis are necessary measures for reducing long-term radiological risks to ISS inhabitants and for meeting legal ALARA requirements. Verification of shield concepts requires results from specific designs to be compared with onboard dosimetry.

Shavers, M. R.; Zapp, N.; Barber, R. E.; Wilson, J. W.; Qualls, G.; Toupes, L.; Ramsey, S.; Vinci, V.; Smith, G.; Cucinotta, F. A.

2004-01-01

323

Implementation of ALARA radiation protection on the ISS through polyethylene shielding augmentation of the Service Module crew quarters  

NASA Astrophysics Data System (ADS)

With 5 to 7-month long duration missions at 51.6° inclination in Low Earth Orbit, the ionizing radiation levels to which International Space Station (ISS) crewmembers are exposed will be the highest planned occupational exposures in the world. Even with the expectation that regulatory dose limits will not be exceeded during a single tour of duty aboard the ISS, the "as low as reasonably achievable" (ALARA) precept requires that radiological risks be minimized when possible through an dose optimization process. Judicious placement of efficient shielding materials in locations where crewmembers sleep, rest, or work is an important means for implementing ALARA for spaceflight. Polyethylene (Cn Hn ), is a relatively inexpensive, stable, and, with a low atomic number, an effective shielding material that has been certified for use aboard the ISS. Several designs for placement of slabs or walls of polyethylene have been evaluated for radiation exposure reduction in the Crew Quarters (CQ) of the Zvezda (Star) Service Module. Optimization of shield designs relies on accurate characterization of the expected primary and secondary particle environment and modeling of the predicted radiobiological responses of critical organs and tissues. Results of the studies shown herein indicate that 20% or more reduction in dose equivalent to the CQ occupant is achievable. These results suggest that shielding design and risk analysis are necessary measures for reducing long-term radiological risks to ISS inhabitants and for meeting legal ALARA requirements. Verification of shield concepts requires results from specific designs to be compared with onboard dosimetry.

Shavers, M.; Zapp, N.; Barber, R.; Wilson, J.; Qualls, G.; Toupes, L.; Ramsey, S.; Vinci, V.; Smith, G.; Cucinotta, F.

324

Shield Optimization in Simple Geometry for the Gateway Concept.  

National Technical Information Service (NTIS)

The great cost of added radiation shielding is a potential limiting factor in many deep space missions. For this enabling technology, we are developing tools for optimized shield design over multi-segmented missions involving multiple work and living area...

R. K. Tripathi L. C. Simonsen J. E. Nealy

2003-01-01

325

Summary of Prometheus Radiation Shielding Nuclear Design Analysis  

SciTech Connect

This report transmits a summary of radiation shielding nuclear design studies performed to support the Prometheus project. Together, the enclosures and references associated with this document describe NRPCT (KAPL & Bettis) shielding nuclear design analyses done for the project.

J. Stephens

2006-01-13

326

High-Density Braid Cable Shields. Final Report.  

National Technical Information Service (NTIS)

Development and improvement of electromagnetic radiation (EMR) shielding was undertaken. The study included cable braiding equipment, induction soldering, shield effectiveness and quality testing, and nondestructive defect locating equipment. (ERA citatio...

E. Belarde

1978-01-01

327

6. View shows Shield 11, looking west. Typical concrete debris ...  

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

6. View shows Shield 11, looking west. Typical concrete debris shield. - Lake Hodges Flume, Along San Dieguito River between Lake Hodges & San Dieguito Reservoir, Rancho Santa Fe, San Diego County, CA

328

Shielding of Manned Space Vehicles Against Protons and alpha Particles.  

National Technical Information Service (NTIS)

The available information on the shielding of manned space vehicles against protons and alpha particles is summarized. The emphasis is placed on shielding against Van Allen belt protons and against solar-flare protons and alpha particles, but information ...

R. G. Alsmiller R. T. Santoro J. Barish H. C. Claiborne

1972-01-01

329

30 CFR 56.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2010 CFR

... 2009-07-01 2009-07-01 false Ventilation and shielding for welding. 56.14213 Section 56.14213 Mineral...and Operational Procedures § 56.14213 Ventilation and shielding for welding. (a) Welding operations shall be...

2009-07-01

330

30 CFR 57.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 2010-07-01 false Ventilation and shielding for welding. 57.14213 Section 57.14213 Mineral...and Operational Procedures § 57.14213 Ventilation and shielding for welding. (a) Welding operations shall be...

2010-07-01

331

30 CFR 57.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2010 CFR

... 2009-07-01 2009-07-01 false Ventilation and shielding for welding. 57.14213 Section 57.14213 Mineral...and Operational Procedures § 57.14213 Ventilation and shielding for welding. (a) Welding operations shall be...

2009-07-01

332

30 CFR 56.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 2010-07-01 false Ventilation and shielding for welding. 56.14213 Section 56.14213 Mineral...and Operational Procedures § 56.14213 Ventilation and shielding for welding. (a) Welding operations shall be...

2010-07-01

333

Early test facilities and analytic methods for radiation shielding: Proceedings  

SciTech Connect

This report represents a compilation of eight papers presented at the 1992 American Nuclear Society/European Nuclear Society International Meeting. The meeting is of special significance since it commemorates the fiftieth anniversary of the first controlled nuclear chain reaction. The papers contained in this report were presented in a special session organized by the Radiation Protection and Shielding Division in keeping with the historical theme of the meeting. The paper titles are good indicators of their content and are: (1) The origin of radiation shielding research: The Oak Ridge experience, (2) Shielding research at the hanford site, (3) Aircraft shielding experiments at General Dynamics Fort Worth, 1950-1962, (4) Where have the neutrons gone , a history of the tower shielding facility, (5) History and evolution of buildup factors, (6) Early shielding research at Bettis atomic power laboratory, (7) UK reactor shielding: then and now, (8) A very personal view of the development of radiation shielding theory.

Ingersoll, D.T. (comp.) (Oak Ridge National Lab., TN (United States)); Ingersoll, J.K. (comp.) (Tec-Com, Knoxville, TN (United States))

1992-11-01

334

Neutron shielding material based on colemanite and epoxy resin.  

PubMed

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. PMID:16381724

Okuno, Koichi

2005-01-01

335

Impact damage on shielded gas-filled vessels  

NASA Astrophysics Data System (ADS)

This paper gives a summary of the findings from impacts on shielded gas-filled cylindrical aluminium alloy (A12219 T851) and titanium alloy (Ti6A14V) pressure vessels that were performed at the Ernst-Mach-Institute in the frame of an ESA contract. The effect of impacts on shielded vessels with projectiles that have a kinetic energy close to the ballistic limit of the combined system of shield and vessel's front wall was investigated. The shields were single Al-bumper plates, unreinforced MLI and MLI reinforced with 2 layers of Betacloth. The threshold diameters that cause leakage from the vessel's front wall were determined experimentally as a function of shield material and shield spacing. For Al-shielded Al- and Ti-vessels, a safety design factor to avoid leakage is presented based on existing Whipple shield equations.

Schäfer, F.; Schneider, E.; Lambert, M.

2001-10-01

336

Gravity Scaling of a Power Reactor Water Shield.  

National Technical Information Service (NTIS)

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 ...

J. B. Pearson R. S. Reid

2008-01-01

337

Design and evaluation of an inexpensive radiation shield for ...  

Treesearch

Jul 21, 2013 ... This paper describes a low-cost (~3 USD) radiation shield (radshield) ... When compared with observations from a high-quality temperature sensor ... Keywords: solar radiation shield, air temperature, microclimate, topoclimate.

338

Geoscientists Explore the Earth  

NSDL National Science Digital Library

Visit the American Geological Institute (AGI) Earth Science Week website to learn about how you can provide your students with inquiry-based learning experiences that celebrates the theme, "Geoscientists Explore the Earth." On the website you will find events taking place in your community, local organizations to partner with, the many careers available in geoscience, the monthly Earth Science Week Update electronic newsletter, and how you can order an Earth Science Week educator's kit.

Benbow, Ann E.; Camphire, Geoff

2005-10-01

339

Satellites Orbiting Earth  

NSDL National Science Digital Library

In recent years, there has been a push to better understand how Earth works as a system- how land, oceans, air, and life all interact. Satellites in orbit around Earth are a fast and efficient way of gathering remotely sensed data about the planet as a whole. This animated video shows the orbital paths of the satellites in the National Aeronautics and Space Administration (NASA) Earth Observing System (EOS), a collection of satellites that work together to study Earth on a wide scale.

340

Museum of the Earth  

NSDL National Science Digital Library

The Museum of the Earth is a natural history museum that stresses the interdependence of the Earth and its life, fostering public understanding of the environment and Earth's past, present and future. The museum is an exhibit facility for one of the nation's largest fossil collections, providing a resource for the public, teachers and students. It serves regional and national audiences by disseminating educational materials as well as promoting best practices and collaboration among providers of informal Earth system education.

2006-08-14

341

Corrosion protection and EMP/EMI shielding  

SciTech Connect

The high-voltage electrical surges which are released from nuclear explosions are called electromagnetic pulses (EMP). Because they can have adverse effects on aircraft and other weapon system electrical circuits, the DOD has evaluated a variety of approaches to providing protection against EMP and electromagnetic interference (EMI). Researchers are now working to develop conductive sealants which can provide corrosion protection while meeting the EMP/EMI shielding requirements of military aircraft and missiles. Test results indicate that shielding effectiveness increases as dc resistance decreases, and shielding effectiveness does not appear to be a strong function of frequency above the 500-1000 MHz test frequency range. The correlations of resistance and shielding effectiveness necessitates that a low resistance exists across a joint or bond. Thus the researchers recommended that the conductive sealants successfully tested be used on existing and future aircraft and missiles where sealants can be liquid-applied. In addition to the test findings and their applications to the operational arena, a primary outcome of these tests is a set of recommended changes to selected military standards, specifications, and handbooks. These recommendations will be used as inputs to any proceedings conducted for the purpose of modifying those documents.

Brahney, J.H.

1990-06-01

342

Integrated first-wall\\/blanket\\/shield concept  

Microsoft Academic Search

An integrated first-wall\\/blanket\\/shield concept has evolved from the desire to improve the attractiveness and reduce the capital cost of fusion reactors. Design simplicity, improved safety, high performance, and reactor modularization are the key design factors in developing this concept. The main features and analysis of the concept are the subject of this paper.

Gohar

1986-01-01

343

Modelling eddy currents in thin shields  

Microsoft Academic Search

Purpose – The purpose of this paper is to present a simplified rigorous mathematical formulation of the problem of electric currents induced in thin shields with holes yielding more efficient numerical computations with respect to available methods. Design\\/methodology\\/approach – A surface integral equation satisfied by the current density was constructed, which is, subsequently, represented at any point by linear combinations

Florea I. Hantila; Ioan R. Ciric; Augustin Moraru; Mihai Maricaru

2009-01-01

344

Shielding of augmented tendon-tendon repair  

Microsoft Academic Search

Strength and function of autogenic and xenogenic reconstruction of digital extensor tendons was examined in an ovine model. In this study, tendon-graft junctions were formed by either suture augmented with a woven polyester tube (A), or augmented and shielded from surrounding tissues by chemically-treated bovine pericardium (S). By 12 wk, both A and S sheep had returned to full range

G. J. Rogers; B. K. Milthorpe; K. Schindhelm; C. R. Howlett; S. Roe

1995-01-01

345

Hydrocode modeling of advanced debris shield designs  

NASA Astrophysics Data System (ADS)

The NASA Johnson Space Center (JSC) Hypervelocity Impact Test Facility (HIT-F) has developed several low mass, high performance shielding concepts to protect spacecraft from orbital debris and meteoroid impact. Development testing requires shield concept validation in the impact velocity regime from <1 km/s to ~14.5 km/s. Current two-stage light gas gun testing limits maximum impact velocities to 8 km/s; therefore, Sandia National Laboratories and Southwest Research Institute have developed advanced launchers capable of accelerating non-spherical shaped masses to ~15 km/s. Since the shape of the impactor influences final rear wall damage, hydrocodes are employed to evaluate the so called shape effect at velocities greater than 8 km/s. A series of 14 hypervelocity impact simulations were conducted using the CTH hydrocode. Simulations modeled spherical aluminum (Al) and Al flat plate projectiles of various masses impacting double bumper all Al Whipple shields (DB). Experimental results at ~7 km/s are compared with simulation and ballistic limit curves are constructed for the DB Whipple shield in the velocity regime greater than 7 km/s. Comments are also made on the shape effect mass ratio for spherical and flat plate projectiles.

Kerr, J. H.; Christiansen, E. L.; Crews, J. L.

1996-05-01

346

Lunar soil as shielding against space radiation  

Microsoft Academic Search

We have measured the radiation transport and dose reduction properties of lunar soil with respect to selected heavy ion beams with charges and energies comparable to some components of the galactic cosmic radiation (GCR), using soil samples returned by the Apollo missions and several types of synthetic soil glasses and lunar soil simulants. The suitability for shielding studies of synthetic

J. Miller; L. Taylor; C. Zeitlin; L. Heilbronn; S. Guetersloh; M. DiGiuseppe; Y. Iwata; T. Murakami

2009-01-01

347

Radiation resistance of radiation shield rubber.  

National Technical Information Service (NTIS)

The radiation shield rubber of ethylene-propylene copolymer (EPDM) and of chlorinated polyethylene (CM) mixed with a large amount of powder or foil lead were irradiated under vacuum or in oxygen atmosphere by Co-60 gamma rays for an evaluation of the radi...

A. Kasai N. Yamaguchi T. Watanabe T. Seguchi M. Nishii

1990-01-01

348

Shielding efficiency measurements under pulsed electromagnetic fields  

Microsoft Academic Search

The paper describes a method of using the transfer function of a given system to calculate the shielding efficiency (SE) of a protective screen with the help of measurements conducted in the time domain. A high voltage electromagnetic pulse simulator (EMPS) creates the required pulse fields. The radiated field in the working zone of the simulator is measured by a

V. Venkateswarlu; Y. Narayana Rao

1995-01-01

349

Electromagnetic Interference and Shielding: An Introduction. (Revised).  

National Technical Information Service (NTIS)

The basic equations of the electromagnetc field are summarized as far as they are needed in the theory of ElectroMagnetic Interference and Shielding. Through the analysis of the radiation from small current-carrying wires ('electric dipole') and small cur...

A. T. de Hoop D. Quak

1993-01-01

350

Electromagnetic interference shielding effectiveness of carbon materials  

Microsoft Academic Search

Carbon materials for electromagnetic interference (EMI) shielding are reviewed. They include composite materials, colloidal graphite and flexible graphite. Carbon filaments of submicron diameter are effective for use in composite materials, especially after electroplating with nickel. Flexible graphite is attractive for EMI gaskets.

D. D. L. Chung

2001-01-01

351

Origin of NMR shielding in fluorides  

NASA Astrophysics Data System (ADS)

In this work, we analyze in detail the relation between electronic structure and fluorine nuclear magnetic resonance (NMR) shielding in a series of solid state alkali fluorides (LiF, NaF, KF, RbF, and CsF). For that purpose, we use solid-state NMR calculations implemented in the density functional theory full potential wien2k code (APW+lo). Both measurements and calculations show that the NMR shielding varies across the series by approximately 200 ppm. We focus our discussion on an explanation of the origin of the observed trend, and we show that the variation is mainly determined by contributions from “semicore” metal-p and valence F-p bands. More specifically, the trend in fluorine shielding can be related to the small but significant change in the hybridization of these states. A second important ingredient determining the value of the shielding is the presence and position of metal-d states in the unoccupied part of the Kohn-Sham bands. Although the present analysis has been demonstrated for the 19F nucleus in alkali fluorides, the main results are more general and can explain similar trends observed in other solids and for other nuclei.

Laskowski, Robert; Blaha, Peter

2012-06-01

352

SCALE radiation shielding V and V package  

SciTech Connect

Verification and validation (V and V) are essential elements of software quality assurance (QA) for computer codes that are used for scientific calculations. The sponsors of the SCALE code system have required a QA plan and a V and V plan. For purposes of validating and verifying the SCALE shielding codes, a set of problems has been assembled and tested.

Emmett, M.B.; Bowman, S.M.; Broadhead, B.L.

1997-12-01

353

Seismic Properties of the Central Indian Shield  

Microsoft Academic Search

We use broadband seismic data at Hyderabad to investigate average crustal properties of the central Indian shield. Crustal receiver-functions (P to SV conversions) based on data of excellent quality and azimuthal coverage show essen- tially no signal on the transverse component, indicating laterally homogeneous struc- tures near this station. A joint analysis of receiver-functions and the dispersion of fundamental mode

Limei Zhou; Wang-Ping Chen; Serdar Ozalaybey

2000-01-01

354

Electronically shielded solid state charged particle detector  

Microsoft Academic Search

An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged

David K. Balmer; Thomas W. Haverty; Carl W. Nordin; William H. Tyree

1996-01-01

355

Transient electron shield currents in vacuum arcs  

Microsoft Academic Search

It is shown that a conducting shield, as a third electrode in a vacuum arc plasma, can temporarily act as an auxiliary anode. This is due to an inductive shift of arc plasma potential caused by a sufficiently rapid decrease of arc current. Using current injection experiments, the existence of cathode spot activity after circuit current zero is demonstrated and

R. P. P. Smeets

1986-01-01

356

The accuracy of NOVICE electron shielding calculations  

Microsoft Academic Search

NOVICE Monte Carlo calculations of electron transport are compared with SHIELDOSE and ITS calculations and with experimental data for an empty electronics box. The accuracy of NOVICE solid angle sectoring methods relative to Monte Carlo methods is discussed for simple shield geometries

Thomas M. Jordan

1991-01-01

357

Electronically shielded solid state charged particle detector  

Microsoft Academic Search

An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged

D. K. Balmer; T. W. Haverty; C. W. Nordin; W. H. Tyree

1995-01-01

358

Electron Shielding in n-InSb  

Microsoft Academic Search

The effect on bound electrons in donor levels by conduction-band electrons in n-InSb is investigated using a self-consistent calculation. Results of the calculations show that no bound state exists for impurity concentrations greater than 6×1013 cm-3. This shielding appears to be the predominant effect leading to the lack of impurity-binding energy.

S. P. Li; W. F. Love; S. C. Miller

1967-01-01

359

Subsurface Shielding Source Term Specification Calculation  

SciTech Connect

The purpose of this calculation is to establish appropriate and defensible waste-package radiation source terms for use in repository subsurface shielding design. This calculation supports the shielding design for the waste emplacement and retrieval system, and subsurface facility system. The objective is to identify the limiting waste package and specify its associated source terms including source strengths and energy spectra. Consistent with the Technical Work Plan for Subsurface Design Section FY 01 Work Activities (CRWMS M&O 2001, p. 15), the scope of work includes the following: (1) Review source terms generated by the Waste Package Department (WPD) for various waste forms and waste package types, and compile them for shielding-specific applications. (2) Determine acceptable waste package specific source terms for use in subsurface shielding design, using a reasonable and defensible methodology that is not unduly conservative. This calculation is associated with the engineering and design activity for the waste emplacement and retrieval system, and subsurface facility system. The technical work plan for this calculation is provided in CRWMS M&O 2001. Development and performance of this calculation conforms to the procedure, AP-3.12Q, Calculations.

S.Su

2001-04-12

360

President Clinton Defers Missile Shield Decision  

NSDL National Science Digital Library

President Clinton will announce in a speech at Georgetown University today that he will not begin the initial steps to deploy a national missile defense shield, leaving the final decision to his successor. The decision to not begin construction of a radar site in Alaska, designed to track incoming missiles, was apparently the product of several factors. These include the failure of recent tests, strong opposition from Russia and some US allies, and fears that any decision would inevitably become politicized with the election nearing. Vice-President Al Gore has expressed conditional support for a missile shield, while George W. Bush has called for an even more extensive system. The President made his decision after receiving competing advice on the missile shield. William S. Cohen, the defense secretary, had recommended Mr. Clinton begin, while Samuel R. Berger, the President's national security advisor, and others recommended against construction at this point. Work on the project will continue nonetheless, including additional tests of the "kill vehicle" and a new booster rocket. The next President will decide not only whether to build the radar station and other elements of a missile shield infrastructure, but also whether to field the system and break the 1972 Antiballistic Missile Treaty.

De Nie, Michael W.

361

Spallation Neutron Source Radiation Shielding Issues  

Microsoft Academic Search

This paper summarizes results of Spallation Neutron Source calculations to estimate radiation hazards and shielding requirements for activated Mercury, target components, target cooling water, and ⁷Be plateout. Dose rates in the accelerator tunnel from activation of magnets and concrete were investigated. The impact of gaps and other streaming paths on the radiation environment inside the test cell during operation and

Y. Y. Azmy; J. M. Barnes; J. D. Drischler; J. O. Johnston; R. A. Lillie; G. S. McNeilly; R. T. Santoro

1999-01-01

362

Ford Motor Company NDE facility shielding design.  

PubMed

Ford Motor Company proposed the construction of a large non-destructive evaluation laboratory for radiography of automotive power train components. The authors were commissioned to design the shielding and to survey the completed facility for compliance with radiation doses for occupationally and non-occupationally exposed personnel. The two X-ray sources are Varian Linatron 3000 accelerators operating at 9-11 MV. One performs computed tomography of automotive transmissions, while the other does real-time radiography of operating engines and transmissions. The shield thickness for the primary barrier and all secondary barriers were determined by point-kernel techniques. Point-kernel techniques did not work well for skyshine calculations and locations where multiple sources (e.g. tube head leakage and various scatter fields) impacted doses. Shielding for these areas was determined using transport calculations. A number of MCNP [Briesmeister, J. F. MCNPCA general Monte Carlo N-particle transport code version 4B. Los Alamos National Laboratory Manual (1997)] calculations focused on skyshine estimates and the office areas. Measurements on the operational facility confirmed the shielding calculations. PMID:16604635

Metzger, Robert L; Van Riper, Kenneth A; Jones, Martin H

2005-01-01

363

Thermal analysis of JET cryopump nitrogen shield  

Microsoft Academic Search

This work was performed under the collaborative program between DIII-D ADP cryopump and JET pumped divertor. The purpose of the analysis was to reduce the uncertainty in the JET cryopump design by using thermal hydraulic methods developed at GA for DIII-D cryopump. The reference design of JET cryopump nitrogen shield consists of a parallel flow arrangement. This arrangement was selected

Baxi

1991-01-01

364

Cost and Financing of Operation Desert Shield.  

National Technical Information Service (NTIS)

The total U.S. cost of Operation Desert Shield without any hostilities could exceed $130 billion in fiscal year 1991, assuming the forces now in place remain there throughout the fiscal year. This cost consists of three components. One is the baseline cos...

1991-01-01

365

Broadband Seismic Characterization of the Arabian Shield.  

National Technical Information Service (NTIS)

From November 1995 to March 1997 a total of nine broadband temporary stations were deployed across the Saudi Arabian shield. These stations consisted of STS-2 seismometers that recorded continuously at 40 sps on Refraction Technology RT72A-07 dataloggers....

F. L. Vernon J. Berger

1998-01-01

366

Internally shielded beam transport and support system  

Microsoft Academic Search

Due to environmental concerns, the Advanced Photon Source has a policy that disallows any exposed lead within the facility. This creates a real problem for the beam transport system, not so much for the pipe but for the flexible coupling (bellows) sections. A complete internally shielded x-ray transport system, consisting of long transport lines joined by flexible coupling sections, has

W. Schildkamp; H. Brewer

1996-01-01

367

Protective Eye Shield Against Small Fragments.  

National Technical Information Service (NTIS)

Casualty reports from Southeast Asia indicate a need for a small fragment protective eye shield which will not interfere with the normal duties of the user. Commercially available eye goggles which are in accordance with Federal Specification FSN 4240-052...

R. J. Hassett S. L. Hanlein J. E. Goeller

1970-01-01

368

Performance of multilayer insulation with slotted shield  

Microsoft Academic Search

Thermal and evacuating performance can be improved by means of slotting a number of one dimension slots on reflection shields of the multilayer insulation (MLI). The influence of slots on thermal radiation and gas conduction heat fluxes are theoretically studied. Based on the analysis and test, the optimum slot rate and length have been obtained. Experiments also show that the

Guobang Chen; Tao Sun; Jianyao Zheng; Zhixue Huang; Jianping Yu

1994-01-01

369

The Tower Shielding Facility: Its glorious past  

SciTech Connect

The Tower Shielding Facility (TSF) is the only reactor facility in the US that was designed and built for radiation-shielding studies in which both the reactor source and shield samples could be raised into the air to allow measurements to be made without interference from ground scattering or other spurious effects. The TSF proved its usefulness as many different programs were successfully completed. It became active in work for the Defense Atomic Support Agency (DASA) Space Nuclear Auxiliary Power, Defense Nuclear Agency, Liquid Metal Fast Breeder Reactor Program, the Gas-Cooled and High-Temperature Gas-Cooled Reactor programs, and the Japanese-American Shielding Program of Experimental Research, just to mention a few of the more extensive ones. The history of the TSF as presented in this report describes the various experiments that were performed using the different reactors. The experiments are categorized as to the programs which they supported and placed in corresponding chapters. The experiments are described in modest detail, along with their purpose when appropriate. Discussion of the results is minimal, but references are given to more extensive topical reports.

Muckenthaler, F.J.

1997-05-07

370

Internally shielded beam transport and support system  

SciTech Connect

Due to environmental concerns, the Advanced Photon Source has a policy that disallows any exposed lead within the facility. This creates a real problem for the beam transport system, not so much for the pipe but for the flexible coupling (bellows) sections. A complete internally shielded x-ray transport system, consisting of long transport lines joined by flexible coupling sections, has been designed for CARS sector 14 to operate either at high vacuum or as a helium flight tube. It can effectively shield against air scattering of wiggler or undulator white beam with proper placement of apertures, collimators, and masks for direct beam control. The system makes use of male- and female-style fittings that create a labyrinth allowing for continuous shielding through the flexible coupling sections. These parts are precision machined from a ternary hypereutectic lead alloy (cast under 15 inches of head pressure to assure a pinhole-free casting) then pressed into either end (rotatable vacuum flanges) of the bellows assembly. The transport pipe itself consists of a four part construction using a stepped transition ring (Z-ring) to connect an inner tube to the vacuum flange and also to a protective and supportive outer tube. The inner tube is wrapped with 1/16{double_prime} pure lead sheet to a predetermined thickness following the shape of the stepped transition ring for continuous shielding. This design has been prototyped and radiation tested. {copyright} {ital 1996 American Institute of Physics.}

Schildkamp, W.; Brewer, H. [Consortium for Advanced Radiation Sources, University of Chicago, 5640 S. Ellis Ave., Chicago, IL 60637 (United States)

1996-09-01

371

Electromagnetic shielding effectiveness of composite material  

Microsoft Academic Search

The purpose of this paper is to present an engineering study of the electromagnetic shielding effectiveness of composite materials used in space applications. The objective of the study is to identify and quantify the important electrical characteristics of composite materials proposed as substitutes for conventional metal-based structural elements of spacecraft. Current design practices utilized by various developers of spacecraft, particularly

Patrick J. Serna; Gary H. Liechty

1999-01-01

372

Hot cell shield plug extraction apparatus  

DOEpatents

A hot cell installation for the handling of highly radioactive material may comprise a dozen or more interconnected high density concrete vaults, the concrete vault walls having a thickness of approximately three feet. Typically, hot cells are constructed in rows so as to share as many shielding walls as possible. A typical overall length of a row of cells might be 70 yards. A secondary mechanism exists for placing certain objects into a cell. A typical hot cell has been constructed with 8 inch diameter holes through the exterior shielded walls in the vicinity of, and usually above, the viewing windows. It became evident that if the hot cell plugs could be removed and replaced conveniently significant savings in time and personnel exposure could be realized by using these 8 inch holes as entry ports. Fifteen inch cylindrical steel plugs with a diameter of eight inches weigh about two hundred pounds. The shield plug swing mechanism comprises a steel shielding plug mounted on a retraction device that enables the plug to be pulled out of the wall and supports the weight of the pulled out plug. The retraction device is mounted on a hinge, which allows the plug to be swung out of the way so that an operator can insert material into or remove it from the interior of the hot cell and then replace the plug quickly. The hinge mounting transmits the load of the retracted plug to the concrete wall.

Knapp, P.A.; Manhart, L.K.

1994-12-31

373

The early faint sun paradox: Organic shielding of ultraviolet-labile greenhouse gases  

SciTech Connect

Atmospheric mixing ratios of {approximately}10{sup -5 {+-}1} for ammonia on the early Earth would have been sufficient, through the resulting greenhouse warming, to counteract the temperature effects of the faint early sun. One argument against such model atmospheres has been the short time scale for ammonia photodissociation by solar ultraviolet light. Here it is shown that ultraviolet absorption by steady-state amounts of high-altitude organic solids produced from methane photolysis may have shielded ammonia sufficiently that ammonia resupply rates were able to maintain surface temperatures above freezing. 78 refs., 2 figs., 1 tab.

Sagan, C. [Cornell Univ., Ithaca, NY (United States); Chyba, C. [Univ. of Arizona, Tucson, AZ (United States)

1997-05-23

374

Mass of the Earth  

NSDL National Science Digital Library

In this activity, learners use basic measurements of the Earth and pieces of rock and iron to estimate the mass of the Earth. Learners will calculate mass, volume, and density, convert units, and employ the water displacement method. To calculate an even more accurate estimate of the mass of the Earth, this resource includes optional instructions on how to measure the iron core mass.

Muller, Eric

2010-01-01

375

Flat earth upward continuation  

Microsoft Academic Search

For a thorough understanding of flat earth upward continuation, Poisson's integral equation is transformed from a coordinate system with spherical symmetry to one with planar symmetry. The two separate cases of infinite and finite flat earths are considered. In resulting exact forms a functional factor in the integrands is isolated, a factor which allows the translation of a spherical earth

John V. Shebalin

1979-01-01

376

More About “Planet Earth”  

NASA Astrophysics Data System (ADS)

Seven programs, each 1 hour in length, form the centerpiece of Planet Earth: The Living Machine, The Blue Planet, The Climate Puzzle, Tales from Other Worlds, Gifts from the Earth, The Solar Sea, Fate of the EarthMost public television stations will broadcast the series on Wednesday evenings; check local listings for the correct time and station.

377

Layers of the Earth  

NSDL National Science Digital Library

Students use graphs of seismic wave travel times, and value for the diameter of Earth obtained in the Size of the Earth activity, to investigate the internal structure of the Earth and determine that it is layered. Click here to view the full activity on the Kéyah Math Project website.

Semken, Steven; Perkins, Tracy

378

The Dynamic Earth.  

ERIC Educational Resources Information Center

|Discusses how the earth is a dynamic system that maintains itself in a steady state. Areas considered include large/small-scale earth motions, geologic time, rock and hydrologic cycles, and other aspects dealing with the changing face of the earth. (JN)|

Siever, Raymond

1983-01-01

379

A lightweight composite shielding material for electromagnetic gun launchers  

Microsoft Academic Search

There is a need for the development of a lightweight electromagnetic shield that can be easily installed and maintained to provide high-performance shielding for electric gun barrels. In the past few years, there have been advancements in the development of lightweight material, which could be quite useful in the electric gun technology. Material is TI-Shield, manufactured by instruments, Inc. TI-Shield

Warren Williams; Kobi O'Malley

1997-01-01

380

Shielding consideration for the SSCL experimental halls  

SciTech Connect

The Superconducting Super Collider which is being designed and built in Waxahachie, Texas consists Of series of proton accelerators, culminating in a 20 Te proton on proton collider. The collider will be in a tunnel which will be 87 km in circumference and. on average about 30 meters underground. The present design calls for two large interaction halls on the east side of the ring. The shielding for these halls is being designed for an interaction rate of 10{sup 9} Hz or 10{sup 16} interactions per year, based on 10{sup 7} seconds per operational year. SSC guidelines require that the shielding be designed to meet the criterion of 1mSv per year for open areas off site 2mSv per year for open areas on site, and 2mSv per year for controlled areas. Only radiation workers will be routinely allowed to work in controlled areas. It should be pointed that there is a potential for an accidental full beam loss in either of the experimental halls, and this event would consist of the loss of the full circulating beam up to 4 {times} 10{sup 14} protons. With the present design. the calculated dose equivalent for this event is about 10% of the annual dose equivalent for the normal p-p interactions, so that die accident condition does not control the shielding. If, for instance, local shielding within the experimental hall is introduced into the calculations, this could change. The shielding requirements presented here are controlled by the normal p-p interactions. Three important questions were addressed in the present calculations. They are (1) the thickness of the roof over the experimental halls, (2) the configuration of the shafts and adits which give access to the halls, and (3) the problem of ground water and air activation.

Bull, J.; Coyne, J.; Mokhov, N.; Stapleton, G.

1994-03-01

381

Trajectory-based heating analysis for the ESA\\/Rosetta earth return vehicle  

Microsoft Academic Search

A coupled, trajectory based flowfield and material thermal response analysis is presented for the European Space Agency (ESA) proposed Rosetta comet nucleus sample return vehicle. The probe returns to Earth along a hyperbolic trajectory with an entry velocity of 16.5 km\\/sec and requires an ablative heat shield on the forebody. Combined radiative and convective, ablating flowfield analyses were performed for

William D. Henline; Michael E. Tauber

1993-01-01

382

STATE OF DEVELOPMENT IN THE RANGE OF REACTOR SHIELDING. II. THEORY AND PRACTICE  

Microsoft Academic Search

In this second part of the article on reactor shielding, neutron ; shielding is first discussed. Then safety shielding is considered. A brief ; survey on radiation detection instruments used for examination of shielding is ; given. 16 references. (tr-auth);

van Ammers; Ir. H

1960-01-01

383

Shielding performances of ITO transparent windows: Theoretical and experimental characterization  

Microsoft Academic Search

The shielding performance of indium-titanium-oxide (ITO) thin film depends on the characteristics of the impinging electromagnetic field, on the geometry of the shield, and on the frequency range. In this paper, a complete experimental characterization of the shielding effectiveness of ITO transparent windows is performed by using three different approaches. The obtained results are compared in order to define the

Sandra Greco; Maria Sabrina Sarto; Alessio Tamburrano

2008-01-01

384

Space radiation shielding strategies and requirements for deep space missions  

Microsoft Academic Search

Methods for estimating crew exposure to radiation and for evaluating shield requirements for spacecraft equipment and crew are examined. The development status for deterministic space radiation transport computer codes and models of their nuclear interaction inputs, which are useful for estimating the composition and thickness of shield materials, is discussed. The relation between shield thickness and exposures is studied. Estimates

Lawrence W. Townsend; John W. Wilson; John E. Nealy

1989-01-01

385

EBT-P Gamma-Ray-Shielding Analysis.  

National Technical Information Service (NTIS)

First, a one-dimensional scoping study was performed for the gamma-ray shield of the ELMO Bumpy Torus proof-of-principle device to define appropriate shielding material and determine the required shielding thickness. The dose-equivalent results are analyz...

Y. Gohar

1983-01-01

386

EBT-P Gamma-Ray Shielding System.  

National Technical Information Service (NTIS)

An elaborate study was carried out for the coil and biological shield of the ELMO Bumpy Torus proof-of-principle (EBT-P) device. A three-dimensional scoping study for the coil shield was performed for four different shielding options to define the heat lo...

Y. Gohar

1981-01-01

387

21 CFR 886.4750 - Ophthalmic eye shield.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Ophthalmic eye shield. 886.4750 Section 886.4750...Surgical Devices § 886.4750 Ophthalmic eye shield. (a) Identification. An ophthalmic eye shield is a device that consists of a...

2013-04-01

388

Analytical formulation for the shielding effectiveness of enclosures with apertures  

Microsoft Academic Search

An analytical formulation has been developed for the shielding effectiveness of a rectangular enclosure with an aperture. Both the magnetic and electric shielding may be calculated as a function of frequency, enclosure dimensions, aperture dimensions and position within the enclosure. Theoretical values of shielding effectiveness are in good agreement with measurements. The theory has been extended to account for circular

Martin Paul Robinson; Trevor M. Benson; Christos Christopoulos; John F. Dawson; M. D. Ganley; A. C. Marvin; S. J. Porter; David W. P. Thomas

1998-01-01

389

Gravity Scaling of a Power Reactor Water Shield  

Microsoft Academic Search

Water based reactor shielding is being considered as an affordable option for potential use on initial lunar surface reactor power systems. Heat dissipation in the shield from nuclear sources must be rejected by an auxillary 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

Robert S. Reid; J. Boise Pearson

2008-01-01

390

Development of Radiation Transport Codes for Shielding Analysis  

Microsoft Academic Search

A variety of discrete ordinates codes have been developed during the past ten years for radiation shielding calculations in rather complicated geometries and also for transport calculations of Bremsstrahlung photons.For more efficient shielding analyses albedo transport codes have been developed and utilized for practical shielding calculations. Point-energy Monte Carlo codes have come to be available during this period for checking

Kiyoshi TAKEUCHI

1989-01-01

391

The SRB heat shield: Aeroelastic stability during reentry  

Microsoft Academic Search

Wind tunnel tests of a 3% scale model of the aft portion of the SRB equipped with partially scaled heat shields were conducted for the purpose of measuring fluctuating pressure levels in the aft skirt region. During these tests, the heat shields were observed to oscillate violently, the oscillations in some instances causing the heat shields to fail. High speed

C. S. Ventres; E. H. Dowell

1977-01-01

392

Shielding materials for highly penetrating space radiations  

Microsoft Academic Search

Interplanetary travel involves the transfer from an Earth orbit to a solar orbit. Once outside the Earth's magnetosphere, the major sources of particulate radiation are solar cosmic rays (SCR's) and galactic cosmic rays (GCR's). Intense fluxes of SCR's come from solar flares and consist primarily of protons with energies up to 1 GeV. The GCR consists of a low flux

Richard L. Kiefer; Robert A. Orwoll

1995-01-01

393

NASA Earth Observatory images  

NSDL National Science Digital Library

The purpose of NASA's Earth Observatory is to provide a freely-accessible publication on the Internet where the public can obtain new satellite imagery and scientific information about our home planet. The focus is on Earth's climate and environmental change. In particular, the site may be useful to public media and educators. Earth scientists and science writers from all NASA centers, as well as all agencies and universities affiliated with NASA's Earth Science Enterprise, are encouraged to submit articles and/or images for publication on the Earth Observatory.

Administration, National A.

2010-02-16

394

Earth Today 1998 Introduction  

NSDL National Science Digital Library

The ability to see Earth from space has forever changed our view of the planet. We are now able to look at the Earth as a whole, and observe how its atmosphere, oceans, land masses, and life interact as global systems. Earths atmosphere, hydrosphere, geosphere, and biosphere are dynamic, changing on timescales of days, minutes, or even seconds. Monitoring the Earth in near real time allows us to get an up to date picture of conditions on our planet. More SVS visualizations for the Earth Today exhibit can be found in animation ids 328 and 1402.

Kekesi, Alex; Shoan, Wendy; Watters, Tom

1998-10-20

395

Earth Today 1998 Countdown  

NSDL National Science Digital Library

The ability to see Earth from space has forever changed our view of the planet. We are now able to look at the Earth as a whole, and observe how its atmosphere, oceans, land masses, and life interact as global systems. Earths atmosphere, hydrosphere, geosphere, and biosphere are dynamic, changing on timescales of days, minutes, or even seconds. Monitoring the Earth in near real time allows us to get an up to date picture of conditions on our planet. More SVS visualizations for the Earth Today exhibit are in animation ids 1401 and 1402.

Kekesi, Alex; Shoan, Wendy; Watters, Tom

1998-10-20

396

Earth Today 1998  

NSDL National Science Digital Library

The ability to see Earth from space has forever changed our view of the planet. We are now able to look at the Earth as a whole, and observe how its atmosphere, oceans, land masses, and life interact as global systems. Earths atmosphere, hydrosphere, geosphere, and biosphere are dynamic, changing on timescales of days, minutes, or even seconds. Monitoring the Earth in near real time allows us to get an up to date picture of conditions on our planet. More SVS visualizations for the Earth Today exhibit can be found in animation ids 328 and 1401.

Kekesi, Alex; Shoan, Wendy; Watters, Tom

1998-10-20

397

Project Earth Science: Astronomy  

NSDL National Science Digital Library

The hands-on, teacher-tested activities in Project Earth Science: Astronomy brings the sometimes daunting concepts of astronomy down to Earth. Background information, supplementary readings, and suggestions for integrating other disciplines provide the teacher with a framework to launch a successful introduction to astronomy. Students will discover Earth's uniqueness by examining it as a part of the whole--one planet within our Solar System. How did the planets form? Are we seeing a star's present or past? Why is Earth's distance from the Sun so important? Project Earth Science: Astronomy will lead you and your students on an exploration that takes you to the stars and back.

Smith, P. S.

2001-01-01

398

Earth Science Students  

NSDL National Science Digital Library

This site provides varied and vital information for earth science students. Links lead to important and interesting sites that change from time to time. The permanent pages at this site offer information that is of value to all earth science students and some that are for local students. There are animations and visual learning aids, interactive unit notes, practice questions for exams, earth science flash cards, supplementary Lessons, a course curriculum, and conversion calculators. The Current Earth Science page has real-time information about weather, volcanoes, earthquakes, and population. Other pages on this site list a host of earth science news items, earth science computer labs, all of the required earth science reference tables, a glossary, an "ask an expert" page, and a guestbook. Other links lead to information of local concern.

Burrows, Charles

399

The Earth Simulator Center  

NSDL National Science Digital Library

The Earth Simulator Center, funded by the Japanese government, is the birth place of the Earth Simulator, a super computer designed to provide a "holistic simulation of the entire earth system" that "may enable accurate prediction of the future by modelling present conditions based on data about the past." The Journal of the Earth Simulator, which is available online from this website as of June 2004, provides updates on the Earth Simulator and related research. Visitors to this website will also find background information on the Earth Simulator and websites for the four research groups: the Atmosphere & Ocean Simulation Group, the Solid Earth Simulation Group, the Multiscale Simulation Research Group, and the Advanced Perception Research Group. Each website provides an overview of the research and publications. Several collaboration projects are also identified along with images of the Simulator. Other publications include the annual report and newsletters, some of which are available only in Japanese.

2007-12-24

400

EarthLabs  

NSDL National Science Digital Library

EarthLabs is a collection of challenging, lab-based high school Earth science curriculum units, each of which integrates text, hands-on activities, interactive visualizations, video, authentic science data, and data visualization and analysis tools. Each unit highlights the interconnectedness and complexities of the Earth system in the context of a specific content area (including Earth system science, climate, weather, atmosphere, cryosphere, environmental science, hurricanes, drought, fisheries, oceans, carbon cycle), and can be integrated into an existing Earth or environmental science course or used as an independent curriculum unit. In addition to the student portal, EarthLabs provides a separate teacher's guide ("EarthLabs for Educators") that provides background and logistical information, pedagogical guidance, and answers to assessments embedded in the student portal.

2012-05-31

401

EarthLabs  

NSDL National Science Digital Library

EarthLabs is a collection of challenging, lab-based high school Earth science curriculum units, each of which integrates text, hands-on activities, interactive visualizations, video, authentic science data, and data visualization and analysis tools. Each unit highlights the interconnectedness and complexities of the Earth system in the context of a specific content area (including Earth system science, climate, weather, atmosphere, cryosphere, environmental science, hurricanes, drought, fisheries, oceans, carbon cycle), and can be integrated into an existing Earth or environmental science course or used as an independent curriculum unit. In addition to the student portal, EarthLabs provides a separate teacher's guide ("EarthLabs for Educators") that provides background and logistical information, pedagogical guidance, and answers to assessments embedded in the student portal.

402

SHIELDING PROPERTIES OF A SIR MARK A CONTROL ROD DRIVE MECHANISM SHIELDING LABORATORY EXPERIMENT NO. 1 (SL1)  

Microsoft Academic Search

Shielding Laboratory Experimert SL-l is described and the results are ; reported. In this experiment the neutron and gamma ray shielding properties of a ; control rod drive mechanism were determined. Measurements were made for fast ; neutrons, epithermal neutrons, thermal neutrons, and gamma rays. This ; information will be used in evaluating the shielding effectiveness of the ; mechanism.

1954-01-01

403

Changes in earth’s dipole  

Microsoft Academic Search

The dipole moment of Earth’s magnetic field has decreased by nearly $$9\\\\% $$ over the past 150 years and by about 30% over the past 2,000 years according to archeomagnetic measurements. Here, we explore the causes and the implications of this rapid change. Maps of the geomagnetic field on the core–mantle boundary derived from ground-based and satellite measurements reveal that most of

Peter Olson; Hagay Amit

2006-01-01

404

Shielding of Electronic Systems against Transient Electromagnetic Interferences  

NASA Astrophysics Data System (ADS)

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.

Herlemann, H.; Korte, S.; Camp, M.; Garbe, H.; Koch, M.; Sabath, F.

2005-05-01

405

Unradiogenic lead in Earth's upper mantle  

NASA Astrophysics Data System (ADS)

The mantle and continental crust--Earth's main silicate reservoirs--have a lead isotope composition that is too radiogenic to have evolved from primitive Solar System material over 4.57billion years. To account for this imbalance, it has been suggested that unradiogenic lead may have partitioned into the metallic core or lower continental crust. Alternatively, radiogenic lead could have been added to Earth later by meteorite impacts. Unradiogenic lead was discovered in fragments of mantle rocks exhumed in the Horoman massif, Japan, implying that the mantle itself may provide a complementary reservoir of unradiogenic lead. However, it is unclear why this unradiogenic component is not sampled by the melting that generates oceanic basalts. Here we present double-spike lead isotope data for abyssal peridotite rocks, considered to represent suboceanic mantle, exposed on the Atlantic Ocean floor. We find that sulphides dated at about 1.83billion years old and trapped as inclusions in silicate minerals preserve extremely unradiogenic lead isotope compositions. This unradiogenic lead could have been prevented from adding significantly to oceanic basalts if either the silicates shield the sulphide inclusions or if the sulphides reside in refractory mantle rocks that are rarely sampled during melting. We conclude that the lead isotope composition of the silicate Earth could be largely balanced by unradiogenic lead in sulphide in the mantle.

Burton, Kevin W.; Cenki-Tok, Bénédicte; Mokadem, Fatima; Harvey, Jason; Gannoun, Abdelmouhcine; Alard, Olivier; Parkinson, Ian J.

2012-08-01

406

Superconducting magnetic shields for neutral beam injectors. Final report  

SciTech Connect

Large high energy deuterium neutral beams which must be made from negative ions require extensive magnetic shielding against the intense fringe fields surrounding a magnetic fusion power plant. The feasibility of shielding by multilayer sheets of copper-superconducting laminated material was investigated. It was found that, if necessary fabrication techniques are developed, intrinsically stable type II superconductors will be able to shield against the magnetic fields of the fusion reactors. Among the immediate benefits of this research is better magnetic shields for neutral beam injectors in support of DOE's fusion program. Another application may be in the space vehicles, where difficulties in transporting heavy ..mu..-metal sections may make a comparatively light superconducting shield attractive. Also, as high-field superconducting magnets find widespread applications, the need for high-intensity magnetic shielding will increase. As a result, the commercial market for the magnetic shields should expand along with the market for superconducting magnets.

Not Available

1985-04-01

407

Magnetic shielding for the Fermilab Vertical Cavity Test Facility  

SciTech Connect

A superconducting RF cavity has to be shielded from magnetic fields present during cool down below the critical temperature to avoid freezing in the magnetic flux at localized impurities, thereby degrading the cavity intrinsic quality factor Q{sub 0}. The magnetic shielding designed for the Fermilab vertical cavity test facility (VCTF), a facility for CW RF vertical testing of bare ILC 1.3 GHz 9-cell SRF cavities, was recently completed. For the magnetic shielding design, we used two cylindrical layers: a room temperature 'outer' shield of Amumetal (80% Ni alloy), and a 2K 'inner' shield of Cryoperm 10. The magnetic and mechanical design of the magnetic shielding and measurement of the remanent magnetic field inside the shielding are described.

Ginsburg, Camille M.; Reid, Clark; Sergatskov, Dmitri A.; /Fermilab

2008-09-01

408

Peralkaline and peraluminous granites and related mineral deposits of the Arabian Shield, Kingdom of Saudi Arabia  

USGS Publications Warehouse

In the Precambrian Arabian Shield, granitoid plutonic rocks are widespread and range in age from 800 to 550 Ma old; but the mineral-resource potential associated with these plutonic rocks is restricted mainly to the younger, postorogenic granites. Two granite types of current economic interest are zirconium- niobium-enriched per alkaline granites and tin-tungsten-enriched peraluminous granites. Both types are highly evolved, are enriched in lithium, rubidium, and fluorine, and have distinctive mineralogy, textures, and chemistry. The zirconium-niobium-enriched granites are related to medium- to large-sized plutons and complexes of peralkaline granite, and the tin-tungsten-enriched granites are related to medium-sized plutons of biotite or biotite-muscovite granite. Existing geochemical and geologic data for many parts of the Arabian Shield were compiled as a basis for evaluating the resource potential of the granites of the Shield. Commodities associated with granites that have potential for economic mineral deposits include tin, tungsten, molybdenum, beryllium, niobium, tantalum, zirconium, uranium, thorium, rare-earth elements, and fluorite. Prospecting methods useful in discriminating those granites having significant economic potential include reconnaissance geologic mapping, petrographic and mineralogic studies, geochemical sampling of rock and wadi sediment, and radiometric surveying.

Elliott, James E.

1983-01-01

409

Phase shielding soliton in parametrically driven systems.  

PubMed

Parametrically driven extended systems exhibit dissipative localized states. Analytical solutions of these states are characterized by a uniform phase and a bell-shaped modulus. Recently, a type of dissipative localized state with a nonuniform phase structure has been reported: the phase shielding solitons. Using the parametrically driven and damped nonlinear Schrödinger equation, we investigate the main properties of this kind of solution in one and two dimensions and develop an analytical description for its structure and dynamics. Numerical simulations are consistent with our analytical results, showing good agreement. A numerical exploration conducted in an anisotropic ferromagnetic system in one and two dimensions indicates the presence of phase shielding solitons. The structure of these dissipative solitons is well described also by our analytical results. The presence of corrective higher-order terms is relevant in the description of the observed phase dynamical behavior. PMID:23767606

Clerc, Marcel G; Garcia-Ñustes, Mónica A; Zárate, Yair; Coulibaly, Saliya

2013-05-24

410

Phase shielding soliton in parametrically driven systems  

NASA Astrophysics Data System (ADS)

Parametrically driven extended systems exhibit dissipative localized states. Analytical solutions of these states are characterized by a uniform phase and a bell-shaped modulus. Recently, a type of dissipative localized state with a nonuniform phase structure has been reported: the phase shielding solitons. Using the parametrically driven and damped nonlinear Schrödinger equation, we investigate the main properties of this kind of solution in one and two dimensions and develop an analytical description for its structure and dynamics. Numerical simulations are consistent with our analytical results, showing good agreement. A numerical exploration conducted in an anisotropic ferromagnetic system in one and two dimensions indicates the presence of phase shielding solitons. The structure of these dissipative solitons is well described also by our analytical results. The presence of corrective higher-order terms is relevant in the description of the observed phase dynamical behavior.

Clerc, Marcel G.; Garcia-Ñustes, Mónica A.; Zárate, Yair; Coulibaly, Saliya

2013-05-01

411

Electronically shielded solid state charged particle detector  

DOEpatents

An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite. 1 fig.

Balmer, D.K.; Haverty, T.W.; Nordin, C.W.; Tyree, W.H.

1996-08-20

412

Grounding and shielding in the accelerator environment  

SciTech Connect

Everyday features of the accelerator environment include long cable runs, high power and low level equipment sharing building space, stray electromagnetic fields and ground voltage differences between the sending and receiving ends of an installation. This paper pictures some Fermilab installations chosen to highlight significant features and presents practices, test methods and equipment that have been helpful in achieving successful shielding. Throughout the report are numbered statements aimed at summarizing good practices and avoiding pitfalls.

Kerns, Q.

1991-01-01

413

Grounding and shielding in the accelerator environment  

SciTech Connect

Everyday features of the accelerator environment include long cable runs, high power and low level equipment sharing building space, stray electromagnetic fields and ground voltage differences between the sending and receiving ends of an installation. This paper pictures some Fermilab installations chosen to highlight significant features and presents practices, test methods and equipment that have been helpful in achieving successful shielding. Throughout the report are numbered statements aimed at summarizing good practices and avoiding pitfalls.

Kerns, Q.

1991-12-31

414

Spallation Neutron Source Radiation Shielding Issues  

SciTech Connect

This paper summarizes results of Spallation Neutron Source calculations to estimate radiation hazards and shielding requirements for activated Mercury, target components, target cooling water, and {sup 7}Be plateout. Dose rates in the accelerator tunnel from activation of magnets and concrete were investigated. The impact of gaps and other streaming paths on the radiation environment inside the test cell during operation and after shutdown were also assessed.

Azmy, Y.Y.; Barnes, J.M.; Drischler, J.D.; Johnston, J.O.; Lillie, R.A.; McNeilly, G.S.; Santoro, R.T.

1999-11-14

415

The impedance of rf-shielding wires  

SciTech Connect

The authors studied the electrostatic fields due to the longitudinal and transverse perturbations of a charged particle beam with a uniform distribution propagating inside an rf-shielding cage constructed from evenly-spaced conducting wires. The beam and the rf-cage are surrounded by a concentric conducting beam pipe. Simple formulae are derived for estimating the space-charge impedances Numerical examples are given.

Wang, T-S F.; Gluckstern, R.L.

1999-03-29

416

Heavy Metal Pad Shielding during Fluoroscopic Interventions  

PubMed Central

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.

Dromi, Sergio; Wood, Bradford J.; Oberoi, Jay; Neeman, Ziv

2008-01-01

417

SINBAD: Shielding integral benchmark archive and database  

SciTech Connect

SINBAD is a new electronic database developed to store a variety of radiation shielding benchmark data so that users can easily retrieve and incorporate the data into their calculations. SINBAD is an excellent data source for users who require the quality assurance necessary in developing cross-section libraries or radiation transport codes. The future needs of the scientific community are best served by the electronic database format of SINBAD and its user-friendly interface, combined with its data accuracy and integrity.

Hunter, H.T.; Ingersoll, D.T.; Roussin, R.W. [and others

1996-04-01

418

Shielded serpentine traveling wave tube deflection structure  

DOEpatents

A shielded serpentine slow wave deflection structure is disclosed having a serpentine signal conductor within a channel groove. The channel groove is formed by a serpentine channel in a trough plate and a ground plane. The serpentine signal conductor is supported at its ends by coaxial feed through connectors. A beam interaction trough intersects the channel groove to form a plurality of beam interaction regions wherein an electron beam may be deflected relative to the serpentine signal conductor. 4 figures.

Hudson, C.L.; Spector, J.

1994-12-27

419

Ablation Radiation Shields for Nuclear Fusion Rockets  

NASA Astrophysics Data System (ADS)

Pulse nuclear propulsion has been the subject of extensive studies since the 1960's. Early concepts examined external pulse propulsion where small critical mass nuclear devices are ejected from the rear of the rocket. A pusher plate absorbs some of the energy form the detonation, which ablates the plate and provides thrust for the rocket. It is also possible to have the device detonate in an enclosed chamber (i.e., internal pulse propulsion). Again, in this case, ablation is the primary method for applying the thrust. Ablation can not only provide thrust but it can also aid in the dissipation of the heat in a neutron radiation shield. Since high-energy neutrons will be abundant in deuterium-tritium fusion reactions, fusion rockets that use this reaction usually are designed with a radiator to dissipate the heat from the shield. These radiators usually require a considerable mass. Carbon and tungsten ablative shields may be considerably more effective. Ablation and radiation are compared as mechanisms to dissipate the heat. Although ablation is shown to provide a considerable mass saving heat loses at the surfaces will create thermal gradients that will adversely effect the ablation rate, and may significantly increase the mass loss.

Coreano, Luis; Cassenti, Brice N.

2003-01-01

420

Fusion neutronics-streaming, shielding, heating, activation  

NASA Astrophysics Data System (ADS)

The International Thermonuclear Experimental Reactor (ITER) represents an important step towards a fusion power plant. Controlled fusion will be realized in a d-t-plasma magnetically confined by a Tokamak configuration. The first wall of the plasma chamber, blanket and vacuum vessel of ITER form a compact assembly for converting the kinetic energy of fusion neutrons into heat while simultaneously shielding the superconducting coils efficiently against neutron and accompanying photon radiation. This shielding system can be investigated with neutrons generated by low-energy accelerators. We report on experiments concerning shielding and streaming properties of a mock-up where energy spectra of both neutrons and protons were measured. They are compared with predictions of Monte Carlo calculations (code MCNP-4A) using various data libraries. The agreement justified the use of measured spectra as basis to calculate design parameters such as neutron and photon heating, radiation damage, gas production, and activation. Some of these parameters were also directly measured. The results validate the ITER design. .

Freiesleben, H.; Richter, D.; Seidel, K.; Unholzer, S.

2001-07-01

421

Topographic evidence for shield volcanism on Io  

SciTech Connect

Similarities between terrestrial shield volcanoes and a volcano on Io observed in Voyager I imagery of the satellite at 30/sup 0/ S, 246/sup 0/ W are delineated. A photoclinometry model was used to numerically estimate the slope based on the Minnaert photometric function. The slope values are accurate to within 10 deg on the sun-facing slope and 1 deg on the shadow side. As found with shield volcanoes, the feature has a central edifice, 40-50 km in diameter, and a broad, elliptical base, 77 x 90 km across. The summit of the Io volcano is 2.2-2.8 km above the surrounding plane and contains a caldera about 5 km in diameter. The similarity in shape between basaltic terrestrial shield volcanoes and the Io volcano indicates that the Io feature may also be composed of basalt. The composition could be sulfur if the heat flow was under 0.05 W/sq m, as it might have been in later stages of formation. 9 references.

Moore, J.M.; Mcewen, A.S.; Albin, E.F.; Greeley, R.

1986-07-01

422

Thermal analysis of JET cryopump nitrogen shield  

SciTech Connect

This work was performed under the collaborative program between DIII-D ADP cryopump and JET pumped divertor. The purpose of the analysis was to reduce the uncertainty in the JET cryopump design by using thermal hydraulic methods developed at GA for DIII-D cryopump. The reference design of JET cryopump nitrogen shield consists of a parallel flow arrangement. This arrangement was selected due to concern about conduction between warm and cold parts of the shield during cool down transients. Such a parallel flow arrangement in two phase flow may be unstable. Hence, an analysis was undertaken to investigate the conduction effects in the shield for this and other flow arrangements. Thermal analysis was done by a finite element program developed at GA. In this analysis, three flow arrangements were developed for cool down from 300{degree}K to about 80{degree}K. In order to simplify the analysis, coolant was assumed to be a N{sub 2}gas at an inlet temperature of 80{degree}K.

Baxi, C.B.

1991-02-01

423

Shielding effects in 1-D transformation kinetics  

NASA Astrophysics Data System (ADS)

A new derivation is presented for the fraction of material transformed as a function of time,X (t), for 1-D phase transformations which occur via nucleation and growth and which produce anisotropic particles. The derivation, which is coached in terms of agressor and blocker particles, accounts for shielding effects and is more easily generalizable to more complex situations than a previous derivation for X(t) for this problem. Since this 1-D problem is equivalent to the 2-D case in the limit of low seeding density, the accuracy of our resulting formula for X(t) is assessed by illustrative calculations using elliptically shaped particles. It is found that the derived expression is nearly precise. In addition, we examine the influence of particle growth rate anisotropy and particle shape on the importance of shielding effects. We conclude that for growth rate anisotropies (ratio of major to minor axis growth rates) smaller than 5, shielding effects are not very significant. Also, particle shape appears to have a small effect on transformation kinetics.

Birnie, Dunbar P.; Weinberg, Michael C.

1996-02-01

424

Combined therapy for vernal shield ulcer.  

PubMed

A 22-year-old male patient presented with complaints of pain and redness in the right eye. Slitlamp examination revealed giant papillae on both tarsal conjunctivae, bilateral punctate corneal epitheliopathy and a 2.9 x 2.9 mm epithelial defect in the right eye. The diagnosis was bilateral vernal keratoconjunctivitis with shield ulcer in the right eye. Treatment was commenced with prednisolone (1%) eye drops four times daily and sodium hyaluronate (0.1%) eye drops eight times daily. After one week, the patient had improved symptomatically but the epithelial defect remained unchanged. Topical cyclosporine (0.05%) applied eight times per day was added to the regimen of topical corticosteroid and artificial tears. Three weeks after commencing combined therapy, the shield ulcer had healed completely, leaving a corneal opacity that negatively stained with fluorescein. The patient was followed for five months and no recurrence of ulcer was noted, despite the discontinuation of topical cyclosporine and prednisolone. Simultaneous institution of topical corticosteroid, artificial tears and topical cyclosporine seems to augment the therapeutic efficacy of each other and may be a promising regime in the management of shield ulcer. PMID:18045257

Kumar, Sunil

2008-01-01

425

GRAVITATIONAL FIELD SHIELDING AND SUPERNOVA EXPLOSIONS  

SciTech Connect

A new mechanism for supernova explosions called gravitational field shielding is proposed, in accord with a five-dimensional fully covariant Kaluza-Klein theory with a scalar field that unifies the four-dimensional Einsteinian general relativity and Maxwellian electromagnetic theory. It is shown that a dense compact collapsing core of a star will suddenly turn off or completely shield its gravitational field when the core collapses to a critical density, which is inversely proportional to the square of mass of the core. As the core suddenly turns off its gravity, the extremely large pressure immediately stops the core collapse and pushes the mantle material of supernova moving outward. The work done by the pressure in the expansion can be the order of energy released in a supernova explosion. The gravity will resume and stop the core from a further expansion when the core density becomes less than the critical density. Therefore, the gravitational field shielding leads a supernova to impulsively explode and form a compact object such as a neutron star as a remnant. It works such that a compressed spring will shoot the oscillator out when the compressed force is suddenly removed.

Zhang, T. X. [Physics Department, Alabama A and M University, Normal, AL 35762 (United States)

2010-12-20

426

Space life sciences: radiation risk assessment and radiation measurements in low Earth orbit.  

PubMed

The volume contains papers presented at COSPAR symposia in October 2002 about radiation risk assessment and radiation measurements in low Earth orbit. The risk assessment symposium brought together multidisciplinary expertise including physicists, biologists, and theoretical modelers. Topics included current knowledge about known and predicted radiation environments, radiation shielding, physics cross section models, improved ion beam transport codes, biological demonstrations of specific shielding materials and applications to a manned mission to Mars, advancements in biological measurement of radiation-induced protein expression profiles, and integration of physical and biological parameters to assess key elements of radiation risk. Papers from the radiation measurements in low Earth orbit symposium included data about dose, linear energy transfer spectra, and charge spectra from recent measurements on the International Space Station (ISS), comparison between calculations and measurements of dose distribution inside a human phantom and the neutron component inside the ISS; and reviews of trapped antiprotons and positrons inside the Earth's magnetosphere. PMID:15880912

2004-01-01

427

Beta radiation shielding with lead and plastic: effect on bremsstrahlung radiation when switching the shielding order.  

PubMed

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. PMID:17228183

Van Pelt, Wesley R; Drzyzga, Michael

2007-02-01

428

Variables Affecting Earth's Albedo  

NSDL National Science Digital Library

Earth's albedo is the fraction of incoming radiation (sunlight) that is reflected into space. The Earth has an average albedo, which describes how much sunlight is reflected on average for the whole planet and the whole year. The Earth also has a local albedo, which determines how much of the Sun's light is reflected from a particular place at a particular time. The local albedo depends on the particular local surface, which can change seasonally as vegetation changes. It also depends on more rapidly changing things such as snow and clouds. In this lesson, students will investigate one of the variables that affect the Earth's albedo. They will collect and graph data on Earth's albedo from two surface types at the same latitude over a period of two years. They will then use the data to calculate how much difference there is in Earth's albedo between the two locations and suggest reasons for the differences.

429

Earth: Inside and Out  

NSDL National Science Digital Library

This book of 19 essays, written by Earth scientists, provides insight into the dynamic processes that shape the Earth. The essays are supported by case studies describing a range of research projects (including Looking for Life in Antarctica-and Mars, Mapping Mt. Rainer, and Mapping Hot Springs on the Deep Ocean Floor) and profiles of historically significant Earth scientists (Including Inge Lehmann, Milutin Milankovitch, and Harold C. Urey). The essays, case studies, and profiles are organized along the same themes explored in the American Museum of Natural History (AMNH) Gottesman Hall of Planet Earth, (How do we read the rocks?; How has the Earth evolved?; Why are there ocean basins, mountains and continents?; What causes climate and climate change?; Why is the Earth habitable?) a large, permanent exhibition that opened at the Museum in 1999.

2001-05-01

430

Variations in earth rotation  

NASA Astrophysics Data System (ADS)

The present conference on variations in the earth's rotation encompasses geophysical effects on earth rotation (ER) parameters, the relationship of ER with tides and oceans, terrestrial and celestial reference systems for measuring ER, refinements of terrestial reference frames, the relationship between length of day and atmospheric angular momentum, and long-term fluctuations of ER parameters. Specific issues addressed include the variational calculation of wobble modes, the long-period elastic behavior of the earth, tidal deceleration of the earth, geophysical implications of the earth's forced nutations, and the study of fluid-solid earth-coupling processes with satellite altimeter data. Also addressed are atmospheric excitation of the ER rate, ER and climatic periodicities, ENSO-related signals in ER, station coordinates and ER parameters, short-period UT1 variations from Iris daily VLBI observations, and the definition and realization of terrestrial reference systems for monitoring ER.

McCarthy, Dennis D.; Carter, William E.

431

Earth's Changing Surface  

NSDL National Science Digital Library

This site presents changes in the crust and climate of Earth by investigating aspects such as the rock cycle, rock dating, climate and variables that affect the climate, and other processes that change the crust of the Earth. These topics include: the atmosphere and surface of Earth; volcanoes and earthquakes; igneous, sedimentary, and metamorphic rocks; and weathering and erosion. There are also laboratory activities to explore radioactive dating and the asthenosphere as well as a rock formation quiz.

432

EarthWise Journeys  

NSDL National Science Digital Library

EarthWise Journeys is an independent resource for travel adventures worldwide with special emphasis on socially responsible travel, cross-cultural exchange, and the environment. EarthWise Journeys is dedicated to travelers who seek environmental awareness, adventure, personal growth, and discovery of our global community. EarthWise Journeys assists members find fun and rewarding travel adventures, learning opportunities, volunteer trips with non-profits, and personal retreats. In addition to travel planning, members receive newsletters, the discount airfares ...and more.

1998-01-01

433

Sun-Earth Days  

Microsoft Academic Search

Sun-Earth Day is a well-coordinated series of programs, resources and events under a unique yearly theme highlighting the fundamentals of heliophysics research and missions. A menu of activities, conducted throughout the year, inspire and educate participants. Sun-Earth Day itself can vary in date, but usually is identified by a celebration on or near the spring equinox. Through the Sun-Earth Day

J. Thieman; C. Ng; E. Lewis; T. Cline

2010-01-01

434

Earth in Motion: Seasons  

NSDL National Science Digital Library

Earth's orbit around the Sun, together with the tilt of its axis, results in periodic climate changes around the globe known as seasons. Different locations experience different types of climate changes. For example, some places have extreme seasonal changes in temperature, while others have little temperature change but may have rainy and dry seasons. This interactive activity from the Adler Planetarium explains why Earth experiences seasons and has students properly place Earth in its orbit for particular seasons in specific locations.

Foundation, Wgbh E.

2009-07-13

435

Earth at Night  

NASA Video Gallery

This view of Earth at night is a cloud-free view from space as acquired by the Suomi National Polar-orbiting Partnership Satellite. A joint program by NASA and NOAA, Suomi NPP captured this nighttime image by the day-night band of the satellite's Visible Infrared Imaging Radiometer Suite VIIRS. It combines the Earth at night view created by NASA's Earth Observatory with data processed by NOAA's National Geophysical Data Center with the EO Blue Marble: Next Generation. Credit: NASA Goddard/NASA's Earth Observatory/NOAA/DOD › Related story› Download high-res video

gsfcvideo

2012-12-04

436

The Earth's early evolution.  

PubMed

The Archean crust contains direct geochemical information of the Earth's early planetary differentiation. A major outstanding question in the Earth sciences is whether the volume of continental crust today represents nearly all that formed over Earth's history or whether its rates of creation and destruction have been approximately balanced since the Archean. Analysis of neodymium isotopic data from the oldest remnants of Archean crust suggests that crustal recycling is important and that preserved continental crust comprises fragments of crust that escaped recycling. Furthermore, the data suggest that the isotopic evolution of Earth's mantle reflects progressive eradication of primordial heterogeneities related to early differentiation. PMID:7667634

Bowring, S A; Housh, T

1995-09-15

437

Earth and Moon Viewer  

NSDL National Science Digital Library

At this site you can view either a map of the Earth showing the day and night regions at this moment, or view the Earth from the Sun, the Moon, the night side of the Earth, above any location on the planet specified by latitude, longitude and altitude, from a satellite in Earth orbit, or above various cities around the globe. Images can be generated based on a full-colour image of the Earth by day and night, a topographical map of the Earth, up-to-date weather satellite imagery, or a composite image of cloud cover superimposed on a map of the Earth, or a color composite which shows clouds, land and sea temperatures, and ice. In addition to the Earth, you can also view the Moon from the Earth, Sun, night side, above named formations on the lunar surface or as a map showing day and night. A related document compares the appearance of the Moon at perigee and apogee, including an interactive Perigee and Apogee Calculator.

Walker, John

1999-03-27

438

The Flat Earth  

NSDL National Science Digital Library

In this lesson, students are exposed to a compelling idea: the Earth really IS flat! They are challenged to provide evidence for a spherical earth, then present evidence (experiences) for a flat Earth, discuss the relative strengths of the evidence, and reach conclusions. They look at the nature of science and pseudoscience and examine the flat Earth idea in that context. The social context of science is also explored, with the roles of collaboration and past experience biases being emphasized. The role of science in exposing illusions in nature is also mentioned.

Beard, Jean

439

Modulation of the DNA-damage response to HZE particles by shielding.  

PubMed

Ions of high atomic number and energy (HZE particles) pose a significant cancer risk to astronauts on prolonged space missions. On Earth, similar ions are being used for targeted cancer therapy. The properties of these particles can be drastically altered during passage through spacecraft shielding, therapy beam modulators, or the human body. Here, we have used pertinent responses to DNA double-strand breaks (DSBs) to understand the consequences of energy loss versus nuclear fragmentation of Fe ions during passage through shielding or tissue-equivalent materials. Phosphorylation of histone H2AX and recruitment of 53BP1 were used to generate 3D reconstructions of DNA damage in human cells and to follow its repair. Human cells are unable to repair a significant portion of DNA damage induced by Fe ions. DNA-PK and ATM are required, to different extents, for the partial repair of Fe-induced DNA damage. Aluminum shielding has little effect on DNA damage or its repair, confirming that the hulls of the Space Shuttle and the International Space Station afford scant protection against these particles. Lead shielding, on the other hand, exacerbates the effects of Fe ions due to energy loss during particle traversal. In sharp contrast, polyethylene (PE), a favored hydrogenous shield, results in DNA damage that is more amenable to repair presumably due to Fe-ion fragmentation. Human cells are indeed able to efficiently repair DSBs induced by chlorine ions and protons that represent fragmentation products of Fe. Interestingly, activation of the tumor suppressor p53 in Fe-irradiated cells is uniquely biphasic and culminates in the induction of high levels of p21 (Waf1/Cip1), p16 (INK4a) and senescence-associated beta-galactosidase activity. Surprisingly, these events occur even in the absence of ATM kinase implying that ATR may be a major responder to the complex DNA damage inflicted by Fe ions. Significantly, fragmentation of the Fe beam through PE attenuates these responses and this, in turn, results in better long-term survival in a colony-forming assay. Our results help us to understand the biological consequences of ion fragmentation through materials, whether in space or in the clinic, and provide us with a biological basis for the use of hydrogenous materials like PE as effective space shields. PMID:18672098

Mukherjee, Bipasha; Camacho, Cristel Vanessa; Tomimatsu, Nozomi; Miller, Jack; Burma, Sandeep

2008-08-13

440

Spatiotemporal relationships of dike magmatism in the Kola region, the Fennoscandian Shield  

NASA Astrophysics Data System (ADS)

A brief geological and petrographic characterization of the Early Precambrian dike complexes of the Kola region is given along with data on new estimates of dike age and analysis of their distribution over the entire Fennoscandian Shield. The emplacement of dikes in the Archean core of the shield continued after consolidation of the sialic crust 2.74-1.76 Ga ago. After the Svecofennian Orogeny, dikes continued to form in the west in the area of newly formed crust, while the amagmatic period began in the Archean domain. The intense formation of dikes in the Svecofennian domain lasted approximately for 1 Ga (1.8-0.84 Ga). The younger igneous rocks in the crustal domains of different age are less abundant and localized at their margins. A similar distribution of dikes is characteristic of other shields in different continents. This implies that the formation of the sialic crust in the shields is not completed by its consolidation and formation of the craton. For 1 Ga after completion of this process, the crust is underplated by mantle-derived magmas. This process is reflected at the Earth's surface in the development of mantle-derived mafic and anorogenic granitoid magmatism. The process of crust formation is ended as the subcratonic lithosphere cools and the amagmatic period of the craton history is started. Beginning from this moment, the manifestations of cratonic magmatism were related either to the superposed tectonomagmatic reactivation of the cold craton under the effect of crust formation in the adjacent mobile belts or to the ascent of mantle plumes.

Fedotov, Zh. A.; Bayanova, T. B.; Serov, P. A.

2012-11-01

441

Snow shielding factors for cosmogenic nuclide dating inferred from Monte Carlo neutron transport simulations  

NASA Astrophysics Data System (ADS)

Conventional formulations of changes in cosmogenic nuclide production rates with snow cover are based on a mass-shielding approach, which neglects the role of neutron moderation by hydrogen. This approach can produce erroneous correction factors and add to the uncertainty of the calculated cosmogenic exposure ages. We use a Monte Carlo particle transport model to simulate fluxes of secondary cosmic-ray neutrons near the surface of the Earth and vary surface snow depth to show changes in neutron fluxes above rock or soil surface. To correspond with shielding factors for spallation and low-energy neutron capture, neutron fluxes are partitioned into high-energy, epithermal and thermal components. The results suggest that high-energy neutrons are attenuated by snow cover at a significantly higher rate (shorter attenuation length) than indicated by the commonly-used mass-shielding formulation. As thermal and epithermal neutrons derive from the moderation of high-energy neutrons, the presence of a strong moderator such as hydrogen in snow increases the thermal neutron flux both within the snow layer and above it. This means that low-energy production rates are affected by snow cover in a manner inconsistent with the mass-shielding approach and those formulations cannot be used to compute snow correction factors for nuclides produced by thermal neutrons. Additionally, as above-ground low-energy neutron fluxes vary with snow cover as a result of reduced diffusion from the ground, low-energy neutron fluxes are affected by snow even if the snow is at some distance from the site where measurements are made.

Zweck, Christopher; Zreda, Marek; Desilets, Darin

2013-10-01

442

Architecture Earth-Sheltered Buildings. Design Manual 1.4.  

National Technical Information Service (NTIS)

Design guidance is presented for use by experienced engineers and architects. The types of buildings within the scope of this manual include slab-on-grade, partially-buried (bermed) or fully-buried, and large (single-story or multistory) structures. New c...

1984-01-01

443

Shielding aspects of D- sup 3 He fusion power reactors  

SciTech Connect

In this paper the implications of the D-{sup 3}He fuel cycle on shielding design are investigated for tokamak power reactors of the ARIES/Apollo class. The prime function of the shield is to protect the superconducting magnets against radiation. A variety of shield options is examined, and the various shields are optimized for the D-{sup 3}He neutron spectrum. The results demonstrate the relative merits of the various materials as a function of the shield thickness. In the first wall/shield, low-activation structural materials (such as Tenelon, modified HT-9, silicon carbide composites, and carbon-carbon composites) were employed to reduce the radioactive inventory and increase the safety margin in case of accidents. A comparison between the different shield options based on detailed neutronics, environmental/safety, and economic assessments has led to the selection of the reference shield design. The first-wall/shield structure is made of an elementally tailored ferritic steel (MHT-9), and the thermal energy is converted through an organic coolant at 44% efficiency. The safety features of the low-activation steel shield, along with the low neutron production in the D-{sup 3}He fuel cycle, enable the ARIES-III/Apollo design to achieve acceptable environmental and safety characteristics.

El-Guebaly, L.A. (Wisconsin Univ., Madison, WI (United States). Fusion Technology Inst.)

1992-08-01

444

Petrology and geochemistry of shield-building and post-erosional lava series of Samoa: implications for mantle heterogeneity and magma genesis  

SciTech Connect

Samoan shield-building lavas are more alkalic than Hawaiian shield basalts, but a transition from less- to more-alkalic flows may be identified in the Pago Shield of Tutuila. This transition is not gradational, but rather consists of alternating less- and more-alkalic interbedded flows, indicating little magma mixing during this period, a conclusion supported by extreme isotopic heterogeneity in these flows. Further evolution of the Pago shield lava compositions is controlled by fractionation of olivine to produce increasingly Si-enriched differentiates. Samoan post-erosional lavas are distinct from Samoan shield-building lavas. They are strongly Si-undersaturated and unfractionated, and show higher YXSr/YWSr and SXPb/SUPb and lower UTNd/ UUNd isotopic ratios than shield-building lavas. Whereas shield-building lavas have isotopic compositions similar to the Society Islands, post-erosional lavas may represent mixing of this shield source with an enriched end member, tentatively identified as recycled crustal material. Compositional variation within the post-erosional lavas is controlled by source differences evident in rare earth element and isotopic compositions, and minor fractionation of olivine, Ti-magnetite, and clinopyroxene. The close spacing of vents along a 282-km-long rift zone parallel to the trend of the island chain, and the anomalously large volume of post-erosional lavas are inconsistent with a plume origin. Two types of ultramafic xenoliths are included in Samoan post-erosional lavas: harzburgite-lherzoilite nodules showing porphyroclastic and equigranular-mosaic textures, and wehrlite-dunites showing tectonized cumulate textures.

Wright, E.

1986-01-01

445

Earth as a System  

NSDL National Science Digital Library

The representation shows earthquake and volcanic activity corresponds to plate boundaries. This video clip is part of a movie that describes the Earth as a system. The clip referenced in this review begins midway through the video, with the statement "Draining the ocean reveals that the Earth's solid surface..." and concludes with "Like earthquakes, most volcanoes are located near plate boundaries."

446

Low Level Earth Motion.  

National Technical Information Service (NTIS)

Contents: Constructing P-velocity models to fit restricted sets of travel-time data; Inversion of inaccurate gross earth data; Tidal to seismic frequency investigations with a quartz; Accelerometer of new geometry; Earth normal modes from a 6.5 magnitude ...

R. A. Haubrich G. Backus B. Block F. Gilbert R. D. Moore

1970-01-01

447

Rare earth permanent magnets  

Microsoft Academic Search

A survey is given of the state of the art in rare earth permanent magnet research of materials based on Nd2Fe14B. The magnetic properties of various types of interstitially modified Fe-rich rare earth intermetallics are discussed, including the possibility to apply these materials in permanent magnets.

K. H. J. Buschow; F. H. Feijen; Kees de Kort

1995-01-01

448

Density of the Earth  

NSDL National Science Digital Library

This demonstration of average density uses understandable units of total mass and volume of the Earth. The required supplies are a can of beer or soda and a 1-pound bag of pretzels. By imagining, for instance, 4.4 bags of pretzels fitting into a beer/soda can, students can better visualize the average density of the Earth.

Barker, Jeffrey

449

The Earth's Dynamic Magnetotail  

Microsoft Academic Search

Geomagnetic field lines that are stretched on the nightside of the Earth due to reconnection with the interplanetary magnetic field constitute the Earth's magnetotail. The magnetotail is a dynamic entity where energy imparted from the solar wind is stored and then released to generate disturbance phenomena such as substorms. This paper gives an updated overview on the physics of the

A. Nishida

2000-01-01

450

Earth System Science Project  

ERIC Educational Resources Information Center

|For several decades, science teachers have used bottles for classroom projects designed to teach students about biology. Bottle projects do not have to just focus on biology, however. These projects can also be used to engage students in Earth science topics. This article describes the Earth System Science Project, which was adapted and developed…

Rutherford, Sandra; Coffman, Margaret

2004-01-01

451

Earth Charter Initiative  

NSDL National Science Digital Library

The Earth Charter is a declaration of fundamental principles for building a just, sustainable, and peaceful global society in the 21st century. The principles of the Earth Charter reflect extensive international consultations conducted over a period of many years. These principles are also based upon contemporary science, international law, and the insights of philosophy and religion.

2007-09-28

452

Know Your Earth  

NASA Video Gallery

This animated video shares a series of fascinating facts about how climate change affects oceans, land, the atmosphere and ice sheets around the world. With the help of an animated astronaut touring the Earth, the video explains how NASA’s Earth-observing satellite fleet enables scientists to gather accurate data and understand those changes.

gsfcvideo

2010-06-30

453

NASA Visible Earth: Runoff  

NSDL National Science Digital Library

The NASA Visible Earth site is a searchable collection of images of the Earth taken by orbiting satellites. This section features a variety of images specifically illustrating effects of runoff. Each image is available in one or more graphic formats and sizes, and is accompanied by a description, as well as detailed metadata about how the image was obtained.

454

The Earth Charter  

ERIC Educational Resources Information Center

|Humanity is part of a vast evolving universe. Earth is alive with a unique community of life. The forces of nature make existence a demanding and uncertain adventure, but Earth has provided the conditions essential to life's evolution. The resilience of the community of life and the well-being of humanity depend upon preserving a healthy…

Journal of Education for Sustainable Development, 2010

2010-01-01

455

The Earth's Core.  

ERIC Educational Resources Information Center

|The nature of the earth's core is described. Indirect evidence (such as that determined from seismological data) indicates that it is an iron alloy, solid toward its center but otherwise liquid. Evidence also suggests that it is the turbulent flow of the liquid that generates the earth's magnetic field. (JN)|

Jeanloz, Raymond

1983-01-01

456

Candy Bar Earth  

NSDL National Science Digital Library

Students model Earth's interior and plate tectonics (movement at the boundaries) by manipulating taffy and a Milky Way candy bar. This is a worksheet-led activity to help students "visualize" the movement of the plates and to relate Earth's interior to objects they see on a regular basis.

Workshop, Rocks A.

2009-05-04

457

Earth Science Vocabulary Review  

NSDL National Science Digital Library

This collection of activities lets students test their knowledge of hundreds of random geologic terms. The activities include games such as hangman (several varieties), flash cards, guessing words or definitions, and matching terms with definitions. Topics include rocks and minerals, Earth dynamics, Earth history, surface processes, weather, and astronomy.

458

Earth Island Institute  

NSDL National Science Digital Library

Visitors to this homepage can learn about the Earth Island Institute and its mission, origins, and purpose. Materials include summaries of projects designed to promote conservation, preservation, and restoration of the Earth, a biography of the organization's founder, news articles, and information for people who wish to become involved in conservation or outreach efforts.

459

Earth as a System  

NSDL National Science Digital Library

This short video uses animated imagery from satellite remote sensing systems to illustrate that Earth is a complex, evolving body characterized by ceaseless change. Adapted from NASA, this visualization helps explain why understanding Earth as an integrated system of components and processes is essential to science education.

Wgbh/boston

460

Earth Science Books  

NSDL National Science Digital Library

This OLogy reference list has nine kid-friendly books on Earth science. A short description is given for each title, along with author name and publisher. The list includes illustrated looks at the powerful forces of nature, hands-on science activities for kids that introduce them to how the Earth works, guides to weather, rocks and minerals, the solar system, and more.

461

Development of neutron shielding material using metathesis-polymer matrix  

NASA Astrophysics Data System (ADS)

A neutron shielding material using a metathesis-polymer matrix, which is a thermosetting resin, was developed. This shielding material has characteristics that can be controlled for different mixing ratios of neutron absorbers and for formation in the laboratory. Additionally, the elastic modulus can be changed at the hardening process, from a flexible elastoma to a mechanically tough solid. Experiments were performed at the Kyoto University Research Reactor in order to determine the important characteristics of this metathesis-polymer shielding material, such as neutron shielding performance, secondary gamma-ray generation and activation. The metathesis-polymer shielding material was shown to be practical and as effective as the other available shielding materials, which mainly consist of thermoplastic resin.

Sakurai, Yoshinori; Sasaki, Akira; Kobayashi, Tooru

2004-04-01

462

Shielding Design of the Spallation Neutron Source (SNS)  

SciTech Connect

The shielding design is important for the construction of an intense high-energy accelerator facility like the proposed Spallation Neutron Source (SNS) due to its impact on conventional facility design, maintenance operations, and since the cost for the radiation shielding shares a considerable part of the total facility costs. A calculational strategy utilizing coupled high energy Monte Carlo calculations and multi-dimensional discrete ordinates calculations, along with semi-empirical calculations, was implemented to perform the conceptual design shielding assessment of the proposed SNS. Biological shields have been designed and assessed for the proton beam transport system and associated beam dumps, the target station, and the target service cell and general remote maintenance cell. Shielding requirements have been assessed with respect to weight, space, and dose-rate constraints for operating, shutdown, and accident conditions. A discussion of the proposed facility design, conceptual design shielding requirements, calculational strategy, source terms, preliminary results and conclusions, and recommendations for additional analyses are presented.

Johnson, J.O.

1998-09-17

463

The Spallation Neutron Source (SNS) conceptual design shielding analysis  

SciTech Connect

The shielding design is important for the construction of an intense high-energy accelerator facility like the proposed Spallation Neutron Source (SNS) due to its impact on conventional facility design, maintenance operations, and since the cost for the radiation shielding shares a considerable part of the total facility costs. A calculational strategy utilizing coupled high energy Monte Carlo calculations and multi-dimensional discrete ordinates calculations, along with semi-empirical calculations, was implemented to perform the conceptual design shielding assessment of the proposed SNS. Biological shields have been designed and assessed for the proton beam transport system and associated beam dumps, the target station, and the target service cell and general remote maintenance cell. Shielding requirements have been assessed with respect to weight, space, and dose-rate constraints for operating, shutdown, and accident conditions. A discussion of the proposed facility design, conceptual design shielding requirements calculational strategy, source terms, preliminary results and conclusions, and recommendations for additional analyses are presented.

Johnson, J.O.; Odano, N.; Lillie, R.A.

1998-03-01

464

Rare earth containing magnets  

SciTech Connect

This patent describes a rare earth-ferromagnetic metal alloy permanent magnet. Produced by the method comprising the steps of: mixing a particular additive material selected from the group consisting of refractory oxides, carbides, and nitrides, in an amount which provides about 0.1 percent to about 2 percent by weight additive material in the mixture, with a major amount of a particulate rare earth-ferromagnetic metal, and a minor amount of a particulate rate earth-ferromagnetic metal sintering aid alloy; aligning magnetic domains of the mixture in a magnetic field; compacting the aligned mixture to form a shape; sintering the compacted shape; and wherein the method produces a magnet composition containing a major phase amount of the particulate rare earth-ferromagnetic metal alloy, a minor phase amount of the particulate rare earth-ferromagnetic metal sintering aid alloy, and added oxide, carbide or nitride from the particulate additive.

Ghandehari, M.H.

1990-01-01

465

The Earth's Atmosphere  

NSDL National Science Digital Library

This section of the Windows to the Universe web site provides information and images about Earth's atmosphere including detailed information about the layers of Earth's atmosphere, the greenhouse effect, and weather. Windows to the Universe is a user-friendly learning system pertaining to the Earth and Space sciences. The objective of this project is to develop an innovative and engaging web site that spans the Earth and Space sciences and includes a rich array of documents, including images, movies, animations, and data sets that explore the Earth and Space sciences and the historical and cultural ties between science, exploration and the human experience. Links at the top of each page allow users to navigate between beginner, intermediate and advanced levels.

Johnson, Roberta

2000-07-01

466

Earth Science Week evolves  

NASA Astrophysics Data System (ADS)

Earth Science Week, October 7-13, is an annual grassroots effort sponsored by the American Geological Institute (AGI) and its member societies, of which AGU is the largest. This year, for the first time, Earth Science Week has a general theme, evolution in Earth history. The Earth Science Week information kit for 2001, available from AGI, includes a variety of posters, bookmarks, and other materials that illustrate this concept. The kit contains a new 32-page “Ideas and Activities” booklet that emphasizes evolution in Earth history through an array of activities about rocks, fossils, and geologic time. It also has information on the upcoming Public Broadcasting Service series, “Evolution,” which is to be aired in late September.

467

Muon diagnostics of the Earth’s atmosphere and magnetosphere  

Microsoft Academic Search

A method of distant monitoring of the Earth’s magnetosphere and atmosphere is described, which is based on the close correlation\\u000a between the modulations in the flux of atmospheric muons detected at the Earth’s surface and the dynamic processes in the\\u000a Earth’s magnetosphere and atmosphere and implies the use of large-area muon hodoscopes with high angular accuracy of muon\\u000a detection. The

N. S. Barbashina; V. V. Borog; A. N. Dmitrieva; R. P. Kokoulin; K. G. Kompaniets; A. A. Petrukhin; D. A. Timashkov; V. V. Shutenko; I. I. Yashin

2007-01-01

468

Thermal shielding of an emerging active region  

NASA Astrophysics Data System (ADS)

Context. The interaction between emerging active regions and the pre-existing coronal magnetic field is important for better understanding the mechanisms of storage and release of magnetic energy from the convection zone to the high corona. Aims: We describe the first steps of an emerging active region within a pre-existing quiet-Sun corona in terms of the thermal and magnetic structure. Methods: We used unprecedented spatial, temporal and spectral coverage from the Atmospheric Imager Assembly (AIA) and from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Results: Starting on 30 May 2010 at 17:00 UT, we followed the emerging active region AR11076 within a quiet-Sun region for 8 h. Using several SDO/AIA filters that cover temperatures from 50 000 K to 10 MK, we show that the emerging process is characterised by a thermal shield at the interface between the emerging flux and pre-existing quiet-Sun corona. Conclusions: The active region 11076 is a peculiar example of an emerging active region because (i) the polarities emerge in a photospheric quiet-Sun region near a supergranular-like distribution, and (ii) the polarities that form the bipolar emerging structure do not rotate with respect to each other, which indicates a slight twist in the emerging flux bundle. There is a thermal shield at the interface between the emerging active region and the pre-existing quiet-Sun region. The thermal shielding structure deduced from all SDO/AIA channels is strongly asymmetric between the two polarities of the active region, suggesting that the heating mechanism for one polarity is probably magnetic reconnection, whilst it is caused by increasing magnetic pressure for the opposite polarity. Appendix A and two movies are available in electronic form at http://www.aanda.org

Régnier, S.

2012-08-01

469

Polyethylene/Boron Composites for Radiation Shielding Applications  

SciTech Connect

Multifunctional composites made with boron are absorbers of low energy nuetrons, and could be used for structural shielding materials. Polyethylene/boron carbide composites were fabricated using conventional polymer processing techniques, and were evaluated for mechanical and radiation shielding properties. Addition of neat boron carbide (powder and nanoparticles) to an injection molding grade HPDE showed superior mechanical properties compared to neat HDPE. Radiation shielding measurements of a 2 wt% boron carbide composite were improved over those of the neat polyethylene.

Harrison, Courtney; Grulke, Eric [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506 (United States); Burgett, Eric; Hertel, Nolan [Neely Nuclear Research Center, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

2008-01-21

470

Radiation shield design for LMFBR spent-fuel shipping casks  

Microsoft Academic Search

Previous analyses have examined a limited number of the alternatives available for designing an LMFBR spent-fuel shipping cask (SFSC) using a non-volatile neutron shield; i.e., a neutron shield which will not be lost in an accident involving a fire. The present study extends the scope of these hypothetical designs to include combinations of volatile and non-volatile neutron shield materials.

Dupree

1977-01-01

471

FWBS Program element II: Blanket and shield testing  

Microsoft Academic Search

The First Wall\\/Blanket\\/Shield (FWBS) Program has the goal to provide the development and testing of FWBS systems for magnetic fusion reactors. Program Element II of this program is to develop the thermal-hydraulic and thermomechanical data base for blanket and shield components. The critical blanket\\/shield data needs were identified, alternate techniques to simulate fusion neutron bulk heating were evaluated, and a

K. R. Schultz; A. R. Veca

1983-01-01

472

Longwall shield design: is bigger better?  

SciTech Connect

This article evaluates the bigger is better design philosophy for longwall shields. The conventional support design approach based on simplistic models of supporting the full dead weight detached rock masses is replaced by a ground reaction design approach. Here, the goal is to match the support characteristics to the ground response, and not to try and overpower the ground forces with some massive support capability. The ground reaction concept embodies both the force and displacement controlled loading aspects, and therefore provides a more accurate representation of the support loading requirements. 7 figs.

Barczak, T.M.; Tadolini, S.C. [NIOSH-PRL, Pittsburgh, PA (United States)

2008-05-15

473

Shielding design at Fermilab: Calculations and measurements  

SciTech Connect

The development of the Fermilab accelerator complex during the past two decades from its concept as the ''200 BeV accelerator'' to that of the present tevatron, designed to operate at energies as high as 1 TeV, has required a coincidental refinement and development in methods of shielding design. In this paper I describe these methods as used by the radiation protection staff of Fermilab. This description will review experimental measurements which substantiate these techniques in realistic situations. Along the way, observations will be stated which likely are applicable to other protron accelerators in the multi-hundred GeV energy region, including larger ones yet to be constructed.

Cossairt, J.D.

1986-11-01

474

X-ray transmissive debris shield  

DOEpatents

An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

Spielman, R.B.

1996-05-21

475

Shielded serpentine traveling wave tube deflection structure  

DOEpatents

A shielded serpentine slow wave deflection structure (10) having a serpene signal conductor (12) within a channel groove (46). The channel groove (46) is formed by a serpentine channel (20) in a trough plate (18) and a ground plane (14). The serpentine signal conductor (12) is supported at its ends by coaxial feed through connectors 28. A beam interaction trough (22) intersects the channel groove (46) to form a plurality of beam interaction regions (56) wherein an electron beam (54) may be deflected relative to the serpentine signal conductor (12).

Hudson, Charles L. (Santa Barbara, CA); Spector, Jerome (Berkeley, CA)

1994-01-01

476

Superconducting shields and manufactured ceramic wares of complex configuration  

NASA Astrophysics Data System (ADS)

A technology has been developed for fabrication of magnetic shields and other high technological wares of superconducting yttrium-barium-copper ceramic by hot casting under pressure. The method enables to form wares of complex configurations and different sizes without any additional machining. The method of hot casting under pressure allows to obtain superconducting shields with a fair homogeneity of the critical field over the shielding length. At working temperature 77, 4K the shields have a threshold screening field Hc* about 1.5 mT, high screening factor (S>104) and low intrinsic noise level (<10-6mT).

Fedorov, Vladimir E.; Pletnev, Peter M.; Korpachev, Michael G.; Korpacheva, Anastasiya I.; Mazhara, Anatoly P.; Dikovskij, Valery Ja.; Gindulina, Venera Z.; Potapova, Olga G.

1991-12-01

477

66. CORBELS, BLIND ARCHES & SHIELDS, COMMONS EAST WALL, LOOKING ...  

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

66. CORBELS, BLIND ARCHES & SHIELDS, COMMONS EAST WALL, LOOKING EAST - Smithsonian Institution Building, 1000 Jefferson Drive, between Ninth & Twelfth Streets, Southwest, Washington, District of Columbia, DC

478

71. Joe Moore, Photographer. September, 1996. BEVATRON ROOF SHIELDING AND ...  

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

71. Joe Moore, Photographer. September, 1996. BEVATRON ROOF SHIELDING AND BUILDING TRUSS STRUCTURE - University of California Radiation Laboratory, Bevatron, 1 Cyclotron Road, Berkeley, Alameda County, CA

479

Radiation protection and shielding standards for the 1980s  

SciTech Connect

The American Nuclear Society (ANS) is a standards-writing organization member of the American National Standards Institute (ANSI). The ANS Standards Committee has a subcommittee denoted ANS-6, Radiation Protection and Shielding, whose charge is to develop standards for radiation protection and shield design, to provide shielding information to other standards-writing groups, and to develop standard reference shielding data and test problems. This paper is a progress report of this subcommittee. Significant progress has been made since the last comprehensive report to the Society.

Trubey, D.K.

1982-01-01

480

Implications of Shield's inverse deformation theorem for compressible finite elasticity  

NASA Astrophysics Data System (ADS)

Some properties of the Shield transformation on elastic strain energy functions are established. It is reflexive, it preserves objectivity and material symmetry for isotropic materials, and it also preserves infinitesimal strain response, ellipticity and Hadamard stability, and the Baker Ericksen condition. Two new classes of strain energies for compressible isotropic materials are introduced, one of them being the image under the Shield transformation of the class of harmonic strain energies. In view of Shield’s Inverse Deformation Theorem, these new classes of strain energies will allow solution in closed form of a variety of problems in finite elastostatics.

Carroll, M. M.; Rooney, F. J.

2005-11-01

481

The Moon and the Earth  

NSDL National Science Digital Library

How does the moon affect the Earth? Read the information on the following websites to help you learn about the moon and the earth. Easy Moon/Earth info Easy Moon Info Moon Information Moon Photos Moon Phases ...

Benson, Carrie

2012-01-06

482

Galileo Earth Views (WMS)  

NSDL National Science Digital Library

The Galileo spacecraft was launched from the Space Shuttle Atlantis on October 18, 1989 on a six-year trip to Jupiter. On the way, the trajectory of the spacecraft took it past Venus once and Earth twice. Galileo took the Earth images in this animation just after the first flyby of the Earth, on December 11 and 12, 1990. This six-hour sequence of images taken two minutes apart clearly shows how the Earth looks from space and how fast (or slow) the cloud features change when looked at from a distance. The path of the sun can be seen crossing Australia by its reflection in the nearby ocean, and the terminator region between night and day can be seen moving across the Indian Ocean. In the original images, the Earths rotation is so dominant that cloud movement is hard to see, but these images have been mapped to the Earth is such a way that a viewer can watch just the clouds move in the ocean around Antarctica or across the Austrailian land mass. In this animation, New Zealand can ony be seen as a stationary disturbance under a moving cloud bank. The black area with the sharp boundary to the north and east of Australia is the side of the Earth that could not be seen from Galileos position.

Mitchell, Horace

2004-08-13

483

Sun-Earth Days  

NASA Astrophysics Data System (ADS)

Sun-Earth Day is a well-coordinated series of programs, resources and events under a unique yearly theme highlighting the fundamentals of heliophysics research and missions. A menu of activities, conducted throughout the year, inspire and educate participants. Sun-Earth Day itself can vary in date, but usually is identified by a celebration on or near the spring equinox. Through the Sun-Earth Day framework we have been able to offer a series of coordinated events that promote and highlight the Sun, its connection to Earth and the other planets. Sun-Earth Day events are hosted by educators, museums, amateur astronomers and scientists and occur at schools, community groups, parks, planetaria and science centers around the globe. Sun-Earth Day raises the awareness and knowledge of formal and informal education audiences concerning space weather and heliophysics. By building on the success of Sun-Earth Day yearly celebrations, we seek to affect people of all backgrounds and ages with the wonders of heliophysics science, discovery, and exploration in ways that are both tangible and meaningful to their lives.

Thieman, J.; Ng, C.; Lewis, E.; Cline, T.

2010-08-01

484

Watering the Earth  

NASA Astrophysics Data System (ADS)

Despite our living embedded in the Earth environment, the origin of water on Earth is one of the most puzzling enigmas in the planetary sciences. Our planet that spawned our watery origins presently carries enough surface water in vapor or liquid form to cover the entire planet to a depth of about 3 km. Earth has substantially more water than scientists would expect to find at 1 A.U. Other compounds and elements also readily vaporize at Earth's distance. Previous proposed solutions to the puzzle considered comets as a viable source of the water, until spectral analysis of the comets Halley, Hyakutake, and Hale-Bopp, during their near-Earth passes in 1986, 1996 and 1997 showed that the abundance of the deuterium isotope of water is twice that found in Earth's water. Recent dynamical models [1] and the current best geochemical and water abundance data indicate that parent bodies from an overlooked region in the solar system, the inner asteroid belt, are promising as the primary source for Earth's water. References [1] O'Brien, David P.; Morbidelli, Alessandro; Levison, Harold F. (2006), Terrestrial Planet Formation with Strong Dynamical Friction, Icarus in press.

Graps, Amara L.; Lunine, J. I.; Coradini, A.; O'Brien, D. P.; Morbidelli, A.

2006-09-01

485

Accretion of the Earth.  

PubMed

The origin of the Earth and its Moon has been the focus of an enormous body of research. In this paper I review some of the current models of terrestrial planet accretion, and discuss assumptions common to most works that may require re-examination. Density-wave interactions between growing planets and the gas nebula may help to explain the current near-circular orbits of the Earth and Venus, and may result in large-scale radial migration of proto-planetary embryos. Migration would weaken the link between the present locations of the planets and the original provenance of the material that formed them. Fragmentation can potentially lead to faster accretion and could also damp final planet orbital eccentricities. The Moon-forming impact is believed to be the final major event in the Earth's accretion. Successful simulations of lunar-forming impacts involve a differentiated impactor containing between 0.1 and 0.2 Earth masses, an impact angle near 45 degrees and an impact speed within 10 per cent of the Earth's escape velocity. All successful impacts-with or without pre-impact rotation-imply that the Moon formed primarily from material originating from the impactor rather than from the proto-Earth. This must ultimately be reconciled with compositional similarities between the Earth and the Moon. PMID:18826928

Canup, Robin M

2008-11-28

486

SHIELDING ANALYSIS FOR PORTABLE GAUGING COMBINATION SOURCES  

SciTech Connect

Radioisotopic decay has been used as a source of photons and neutrons for industrial gauging operations since the late 1950s. Early portable moisture/density gauging equipment used Americium (Am)-241/Beryllium (Be)/Cesium (Cs)-137 combination sources to supply the required nuclear energy for gauging. Combination sources typically contained 0.040 Ci of Am-241 and 0.010 Ci of CS-137 in the same source capsule. Most of these sources were manufactured approximately 30 years ago. Collection, transportation, and storage of these sources once removed from their original device represent a shielding problem with distinct gamma and neutron components. The Off-Site Source Recovery (OSR) Project is planning to use a multi-function drum (MFD) for the collection, shipping, and storage of AmBe sources, as well as the eventual waste package for disposal. The MFD is an approved TRU waste container design for DOE TRU waste known as the 12 inch Pipe Component Overpack. As the name indicates, this drum is based on a 12 inch ID stainless steel weldment approximately 25 inch in internal length. The existing drum design allows for addition of shielding within the pipe component up to the 110 kg maximum pay load weight. The 12 inch pipe component is packaged inside a 55-gallon drum, with the balance of the interior space filled with fiberboard dunnage. This packaging geometry is similar to the design of a DOT 6M, Type B shipping container.

J. TOMPKINS; L. LEONARD; ET AL

2000-08-01

487

SHIELDING REQUIREMENTS FOR NSLS-II.  

SciTech Connect

Brookhaven National Laboratory is in the process of designing a new Electron Synchrotron for scientific research using synchrotron radiation. This facility, called the 'National Synchrotron Light Source II' (NSLS-II), will provide x-ray radiation of ultra-high brightness and exceptional spatial and energy resolution. It will also provide advanced insertion devices, optics, detectors, and robotics, and a suite of scientific instruments designed to maximize the scientific output of the facility. The project scope includes the design, construction, installation, and commissioning of the following accelerators: a 200 MeV linac, a booster accelerator operating from 200 MeV to 3.0 GeV, and the storage ring which stores a maximum of 500 mA current of electrons at an energy of 3.0 GeV. It is planned to operate the facility primarily in a top-off mode, thereby maintaining the maximum variation in stored beam current to < 1%. Because of the very demanding requirements for beam emittance and synchrotron radiation brilliance, the beam life-time is expected to be low, on the order of 2-3 hours. Analysis of the bulk shielding for operating this facility and the input parameters used for this analysis are discussed in this paper. The characteristics of each of the accelerators and their operating modes are summarized with the input assumptions for the bulk shielding analysis.

JOB,P.K.; CASEY, W.R.

2008-01-02

488

Optimization of Shielded Scintillator for Neutron Detection  

NASA Astrophysics Data System (ADS)

The High Energy Density Physics group is interested in the basic science of creating a neutron and gamma ray source. The neutrons and gamma rays are produced by accelerating ions via a laser into a target and creating fusion neutrons and gamma rays. A scintillator and photomultiplier tube will be used to detect these neutrons. Neutrons and photons produce ionizing radiation in the scintillator which then activates metastable states. These metastable states have both short and long decay rates. The initial photon count is orders of magnitude higher than the neutron count and poses problems for accurately detecting the neutrons due to the long decay state that is activated by the photons. The effects of adding lead shielding on the temporal response and signal level of the neutron detector will be studied in an effort to minimize the photon count without significant reduction to the temporal resolution of the detector. MCNP5 will be used to find the temporal response and energy deposition into the scintillator by adding lead shielding. Results from the simulations will be shown. Optimization of our scintillator neutron detection system is needed to resolve the neutron energies and neutron count of a novel neutron and gamma ray source.

Belancourt, Patrick; Morrison, John; Akli, Kramer; Freeman, Richard

2011-11-01

489

Characteristic of the radiation field in low Earth orbit and in deep space.  

PubMed

The radiation exposure in space by cosmic radiation can be reduced through careful mission planning and constructive measures as example the provision of a radiation shelter, but it cannot be completely avoided. The reason for that are the extreme high energies of particles in this field and the herewith connected high penetration depth in matter. For missions outside the magnetosphere ionizing radiation is recognized as the key factor through its impact on crew health and performance. In absence of sporadic solar particle events the radiation exposure in Low Earth orbit (LEO) inside Spacecraft is determined by the galactic cosmic radiation (protons and heavier ions) and by the protons inside the South Atlantic Anomaly (SAA), an area where the radiation belt comes closer to the earth surface due to a displacement of the magnetic dipole axes from the Earth's center. In addition there is an albedo source of neutrons produced as interaction products of the primary galactic particles with the atoms of the earth atmosphere. Outside the spacecraft the dose is dominated by the electrons of the horns of the radiation belt located at about 60" latitude in Polar Regions. The radiation field has spatial and temporal variations in dependence of the Earth magnetic field and the solar cycle. The complexity of the radiation field inside a spacecraft is further increased through the interaction of the high energy components with the spacecraft shielding material and with the body of the astronauts. In interplanetary missions the radiation belt will be crossed in a couple of minutes and therefore its contribution to their radiation exposure is quite small, but subsequently the protection by the Earth magnetic field is lost, leaving only shielding measures as exposure reduction means. The report intends to describe the radiation field in space, the interaction of the particles with the magnetic field and shielding material and give some numbers on the radiation exposure in low earth orbits and in interplanetary missions. PMID:19205293

Reitz, Guenther

2008-01-01

490

Earth's Earliest Atmospheres  

PubMed Central

Earth is the one known example of an inhabited planet and to current knowledge the likeliest site of the one known origin of life. Here we discuss the origin of Earth’s atmosphere and ocean and some of the environmental conditions of the early Earth as they may relate to the origin of life. A key punctuating event in the narrative is the Moon-forming impact, partly because it made Earth for a short time absolutely uninhabitable, and partly because it sets the boundary conditions for Earth’s subsequent evolution. If life began on Earth, as opposed to having migrated here, it would have done so after the Moon-forming impact. What took place before the Moon formed determined the bulk properties of the Earth and probably determined the overall compositions and sizes of its atmospheres and oceans. What took place afterward animated these materials. One interesting consequence of the Moon-forming impact is that the mantle is devolatized, so that the volatiles subsequently fell out in a kind of condensation sequence. This ensures that the volatiles were concentrated toward the surface so that, for example, the oceans were likely salty from the start. We also point out that an atmosphere generated by impact degassing would tend to have a composition reflective of the impacting bodies (rather than the mantle), and these are almost witho