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Implication of the Transport Equation for the Semiempirical Treatment of Shields

Description: Note presenting a revision of the semiempirical method of dealing with shields by treating them as composed of layers by taking the angular distribution of the radiation into account and by making use of the transport equation. The method is illustrated by consideration of the effect upon neutrons of a thick nonabsorbing shield of high atomic weight.
Date: March 1952
Creator: Schwed, Philip
Partner: UNT Libraries Government Documents Department

Studies of Reactor Containment

Description: The following report includes a description of apparatus and techniques for the observation of the behavior of blast shield segments and materials when impulsively loaded, some preliminary dynamic stress-strain data, and some observations of compression wave propagation in porous media.
Date: August 1958
Creator: Napadensky, H. S.; Pinsky, J. & Stresau, R.
Partner: UNT Libraries Government Documents Department

Effect of Structure in Middle Part of Leading Edge of a Thick Wing: Communication From Rijks-Studiedienst Voor De Luchtvaart of Amsterdam

Description: The experiments herein described were made for the purpose of finding whether removing a larger portion of the wing to improve the pilot's view would be possible, without too great detriment to the aerodynamic properties of the airplane. The experiments were conducted on a wing similar to the Fokker F III.
Date: June 1922
Partner: UNT Libraries Government Documents Department

An Overview of Raster Scanning for ICF-Class Laser Optics

Description: Recent work has shown that the damage resistance of both ICF-class (1600 cm') DKDP tripler crystals and SiO{sub 2} components (lenses, gratings and debris shields) benefits from laser raster scanning using pulsed lasers in the 350 nm range. For laser raster scanning to be a viable optical improvement tool for these large optics, damage improvement must be optimized while maintaining scan times of less than 8 hours/optic. In this paper we examine raster scanning with small beams from tabletop laser systems. We show that 120 Watts of average power is required for a tabletop scanning system at one optic/day. Next, we develop equations for total scan time for square and round top hat beams and round and rectangular Gaussian beams. We also consider the effect of packing geometry (square vs. hexagonal), examine the deviations from uniform coverage with each scan geometry and show that hexagonal packing yields lower scan times but is less efficient in coverage than square geometry. We also show that multiple passes at low packing densities are temporally equivalent to a single pass with higher packing density, and discuss the advantages of each method. In addition, we show that the differences between hexagonal and square scan geometries are negated when pointing errors and fluence fluctuations from the laser are considered.
Date: October 30, 2002
Creator: Runkel, M J & Nostrand, M
Partner: UNT Libraries Government Documents Department

Some Notes on the Probable Damage to an Intercontinental-Ballistic-Missile Warhead Following Puncture of the Heat Shield

Description: Report discussing a study of the effects of puncturing the heat shield of an intercontinental-ballistic-missile warhead by small projectiles. Calculations were created for both rod and sphere projectiles and experimental testing was performed on a missile model with holes drilled in the heat shield. The possibility that a projectile could have enough energy to cause mechanical damage to the interior of the warhead is also presented.
Date: September 29, 1958
Creator: Strass, H. K. & Goodman, V. M.
Partner: UNT Libraries Government Documents Department

Shielding Design of the Spallation Neutron Source (SNS)

Description: 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.
Date: September 17, 1998
Creator: Johnson, J.O.
Partner: UNT Libraries Government Documents Department

MOLYBDENUM DISILICIDE MATERIALS FOR GLASS MELTING SENSOR SHEATHS

Description: Sensors for measuring the properties of molten glass require protective sensor sheaths in order to shield them from the extremely corrosive molten glass environment. MoSi{sub 2} has been shown to possess excellent corrosion resistance in molten glass, making it a candidate material for advanced sensor sheath applications. MoSi{sub 2}-coated Al{sub 2}O{sub 3} tubes, MoSi{sub 2}-Al{sub 2}O{sub 3} laminate composite tubes, and MoSi{sub 2}-Al{sub 2}O{sub 3} functionally graded composite tubes have been produced by plasma spray-forming techniques for such applications.
Date: January 1, 2001
Creator: PETROVIC, J.; CASTRO, R. & AL, ET
Partner: UNT Libraries Government Documents Department

Incorporation of Uncertainty and Variability of Drip Shield and Waste Package Degradation in WAPDEG Analysis

Description: This presentation investigates the incorporation of uncertainty and variability of drip shield and waste package degradation in analyses with the Waste Package Degradation (WAPDEG) program (CRWMS M&O 1998). This plan was developed in accordance with Development Plan TDP-EBS-MD-000020 (CRWMS M&O 1999a). Topics considered include (1) the nature of uncertainty and variability (Section 6.1), (2) incorporation of variability and uncertainty into analyses involving individual patches, waste packages, groups of waste packages, and the entire repository (Section 6.2), (3) computational strategies (Section 6.3), (4) incorporation of multiple waste package layers (i.e., drip shield, Alloy 22, and stainless steel) into an analysis (Section 6.4), (5) uncertainty in the characterization of variability (Section 6.5), and (6) Gaussian variance partitioning (Section 6.6). The presentation ends with a brief concluding discussion (Section 7).
Date: April 19, 2000
Creator: Helton, J.C.
Partner: UNT Libraries Government Documents Department

Hydrogen-induced cracking of drip shield

Description: A simple and conservative model has been developed to evaluate the effects of hydrogen-induced cracking on the drip shield. The basic premise of the model is that failure will occur once the hydrogen content exceeds a certain limit or critical value, HC. This model is very conservative because it assumes that, once the environmental and material conditions can support that particular corrosion process, failure will be effectively instantaneous. In the description of the HIC model presented in Section 6.1, extensive evidence has been provided to support a qualitative assessment of Ti-7 as an excellent choice of material for the drip shield with regard to degradation caused by hydrogen-induced cracking. LTCTF test data observed at LLNL, although unqualified, provides additional indication beyond a qualitative level that hydrogen concentration appears to be low in titanium materials. Quantitative evaluation based on the HIC model described in Section 6.1 indicates that the hydrogen concentration does not exceed the critical value. It is concluded that drip shield material (Ti-7) is able to sustain the effects of hydrogen-induced cracking.
Date: August 1, 1999
Creator: Lu, S C
Partner: UNT Libraries Government Documents Department

The Results of Recent MICE Superconducting Spectrometer Solenoid Test

Description: The MICE spectrometer solenoid magnets will be the first magnets to be installed within the MICE cooling channel. The MICE spectrometer solenoids may be the largest magnets that have been cooled using small two stage coolers. During the previous test of this magnet, the cooler first stage temperatures were too high. The causes of some of the extra first stage heat load has been identified and corrected. The rebuilt magnet had a single stage GM cooler in addition to the three pulse tube coolers. The added cooler reduces the temperature of the top of the HTS leads, the shield and of the first stage of the pulse tube coolers.
Date: October 15, 2010
Creator: Green, Michael A.; Virostek, Steve P. & Zisman, Michael S.
Partner: UNT Libraries Government Documents Department

Discovery of Non-random Spatial Distribution of Impacts in the Stardust Cometary Collector

Description: We report the discovery that impacts in the Stardust cometary collector are not distributed randomly in the collecting media, but appear to be clustered on scales smaller than {approx} 10 cm. We also report the discovery of at least two populations of oblique tracks. We evaluated several hypotheses that could explain the observations. No hypothesis was consistent with all the observations, but the preponderance of evidence points toward at least one impact on the central Whipple shield of the spacecraft as the origin of both clustering and low-angle oblique tracks. High-angle oblique tracks unambiguously originate from a non-cometary impact on the spacecraft bus just forward of the collector.
Date: April 6, 2007
Creator: Westphal, A J; Bastien, R K; Borg, J; Bridges, J; Brownlee, D E; Burchell, M J et al.
Partner: UNT Libraries Government Documents Department

Neutronic studies for an integrated beam line shield package at the Lujan Center

Description: We have designed an integrated beam-line shielding package in the Experimental Area 1 (ER-1) for two new scientific instruments (NPT-Gamma and IN500) being constructed at the Manual Lujan Jr. Neutron Scattering Center (Lujan Center). In this work we investigated the neutronics of a guillotine shutter, looked at possible neutron streaming paths, and designed an integrated beam line shield package.
Date: January 1, 2001
Creator: Muhrer, G. (Guenter); Russell, G. J. (Gary J.) & Pitcher, E. J. (Eric J.)
Partner: UNT Libraries Government Documents Department

CONCEPTS FOR CAPACITIVELY RF-SHIELDED BELLOWS IN CRYOGENIC STRUCTURES.

Description: Bellows are frequently required in accelerators and colliders. Usually RF-shields with spring fingers are employed to screen the bellows. The lack of accessibility in cryogenic systems can be a problem and asks for alternate solutions to eliminate possible overheating, sparking, etc that occurred in intensive beams. This note addresses an alternate kind of RF shield, which uses capacitive contact instead of mechanical contact. The analysis, as well as numerical example of a superconducting cavity structure, shows that the capacitive RF shield satisfies the impedance requirements of both beam and HOMs. The capability of thermal isolation is also analyzed.
Date: March 24, 2004
Creator: ZHAO,Y. HAHN,H.
Partner: UNT Libraries Government Documents Department

Structural Design and Thermal Analysis for Thermal Shields of the MICE Coupling Magnets

Description: A superconducting coupling magnet made from copper matrix NbTi conductors operating at 4 K will be used in the Muon Ionization Cooling Experiment (MICE) to produce up to 2.6 T on the magnet centerline to keep the muon beam within the thin RF cavity indows. The coupling magnet is to be cooled by two cryocoolers with a total cooling capacity of 3 W at 4.2 K. In order to keep a certain operating temperature margin, the most important is to reduce the heat leakage imposed on cold surfaces of coil cold mass assembly. An ntermediate temperature shield system placed between the coupling coil and warm vacuum chamber is adopted. The shield system consists of upper neck shield, main shields, flexible connections and eight supports, which is to be cooled by the first stage cold heads of two ryocoolers with cooling capacity of 55 W at 60 K each. The maximum temperature difference on the shields should be less than 20 K, so the thermal analyses for the shields with different thicknesses, materials, flexible connections for shields' cooling and structure design for heir supports were carried out. 1100 Al is finally adopted and the maximum temperature difference is around 15 K with 4 mm shield thickness. The paper is to present detailed analyses on the shield system design.
Date: July 1, 2009
Creator: Green, Michael A.; Pan, Heng; Liu, X. K.; Wang, Li; Wu, Hong; Chen, A. B. et al.
Partner: UNT Libraries Government Documents Department

Integrated Thermal Analysis of the FRIB Cryomodule Design

Description: Thermal analysis of the FRIB cryomodule design is performed to determine the heat load to the cryogenic plant, to minimize the cryogenic plant load, to simulate thermal shield cool down as well as to determine the pressure relief sizes for failure conditions. Static and dynamic heat loads of the cryomodules are calculated and the optimal shield temperature is determined to minimize the cryogenic plant load. Integrated structural and thermal simulations of the 1100-O aluminium thermal shield are performed to determine the desired cool down rate to control the temperature profile on the thermal shield and to minimize thermal expansion displacements during the cool down. Pressure relief sizing calculations for the SRF helium containers, solenoids, helium distribution piping, and vacuum vessels are also described.
Date: July 1, 2012
Creator: Y. Xu, M. Barrios, F. Casagrande, M.J. Johnson, M. Leitner, D. Arenius, V. Ganni, W.J. Schneider, M. Wiseman
Partner: UNT Libraries Government Documents Department