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Value engineering study final report on -- Spallation Neutron Source, Oak Ridge, Tennessee

Description: The SNS Project has had numerous DOE/SC reviews to validate the technical baseline, management approach, cost, schedule, and Conceptual Design Report. As a result, in FY 1999 the SNS received $130 million and approval from Congress to initiate Title 1 design and construction activities. Since this funding was less than requested for FY 1999 ($157 million) and validated in previous reviews, and because of improved costing information, the SNS Project team will reassess the cost and schedule baselines in an upcoming DOE review in January 1999. In preparation for this reassessment, the SNS has initiated a value engineering process to improve the design and to recover cost and contingency. Value engineering will continue throughout the life of the project, but the results described in this report are our initial efforts.
Date: January 31, 1999
Partner: UNT Libraries Government Documents Department

Analysis of interaction phenomena between liquid jets and materials

Description: The interaction phenomena of high-velocity liquid jets impinging on a material surface have been investigated theoretically and experimentally to gain an understanding of the physical mechanisms involved in material removal by fluidjet machining processes. Experiments were performed to determine conditions under which the liquid jet impacting a solid material will cause material removal and also to delineate possible physical mechanisms of mass removal at optimum jet-cutting conditions. We have also carried out numerical simulations of jet-induced surface pressure rises and of the material deformation and spallation behavior due to multiple droplet impacts. Results obtained from the experiments and theoretical calculations and their physical implications are also discussed.
Date: February 1, 1995
Creator: Kang, Sang-Wook; Reitter, T. & Carlson, G.
Partner: UNT Libraries Government Documents Department

Analysis of interaction phenomena between liquid jets and materials. Revision 1

Description: The interaction phenomena of high-velocity liquid jets impinging on a material surface have been investigated theoretically and experimentally to understand the physics of material removal by jet-machining processes. Experiments were performed to delineate conditions under which liquid jet impacts will cause mass removal, and to determine optimum jet-cutting conditions. Theoretical analyses have also been carried out to study the effects of multiple jet-droplet impacts on a target surface as a material deformation mechanism. The calculated target response and spallation behavior following droplet impacts and their physical implications are also discussed.
Date: April 1, 1995
Creator: Kang, S.W.; Reitter, T. & Carlson, G.
Partner: UNT Libraries Government Documents Department

The Delayed-Neutron Fraction in a Pulsed Spallation Neutron Source

Description: The fraction of delayed neutrons beta in slow-neutron beams from a uranium-238 pulsed spallation neutron source is 0.0053 for 300 MeV protons. This measurement appears to be the first one of this quantity. The result indicates that, for most classes of measurements, the delayed-neutron background in time-of-flight instruments will be unimportant, and places constraints on the physics description of spallation targets. The measurement was performed at the prototype pulsed spallation neutron source, ZING-P', at Argonne National laboratory.
Date: February 1980
Creator: Carpenter, J. M.
Partner: UNT Libraries Government Documents Department

Summary of the Research Progress Meeting

Description: This summary of the research progress meeting on March 18, 1948 covers the following topics: (1) Proton-proton scattering at 7 Mev; (2) Some animal experiments with 90 Mev neutrons; and (3) Yields of spallation products of antimony.
Date: March 18, 1948
Creator: Folden, M.F.
Partner: UNT Libraries Government Documents Department

Spall Strength Measurements of Concrete for Varying Aggregate Sizes

Description: Controlled impact experiments have been performed to determine the spall strength of four different concrete compositions. The four concrete compositions are identified as, `SAC-5, CSPC', ("3/4") large, and ("3/8") small, Aggregate. They differ primarily in aggregate size but with average densities varying by less than five percent. Wave profiles from sixteen experiments, with shock amplitudes of 0.07 to 0.55 GPa, concentrate primarily within the elastic regime. Free-surface particle velocity measurements indicate consistent pullback signals in the release profiles, denoting average span strength of approximately 40 MPa. It is the purpose of this paper to present spall measurements under uniaxial strain loading. Notwithstanding considerable wave structure that is a unique characteristic to the heterogeneous nature of the scaled concrete, the spall amplitudes appear reproducible and consistent over the pressure range reported in this study.
Date: May 5, 1999
Creator: Chhabildas, Lalit C.; Kipp, Marlin E.; Reinhart, William D. & Wilson, Leonard T.
Partner: UNT Libraries Government Documents Department

Heating Distributions in the Target of the Spallation Neutron Source

Description: Detailed calculation of the heat distributions in the structural parts of the target (Hg) and the target itself were made with realistic proton profiles. Preliminary current profiles of the protons coming from the accumulator ring, calculated and parameterized by the Brookhaven National Laboratory (BNL), were used as input to the Monte Carlo code LAHET. Due to limitations of the present version of the LAHET code, the real source was approximated with a nest of elliptical rings (all with the same eccentricity). The BNL's source was then fitted according to this elliptical description considering two constraints: (1) to preserve the areas of the contours of equal intensity of the real proton current density, and (2) to keep the ellipses with the same shape. In this way the best elliptical shape to describe the source was found. Because of the gaussian nature of the real current distribution, the elliptical fit is also gaussian in the elliptical coordinate.
Date: November 18, 1999
Creator: Charlton, L.A. & Difilippo, F.C.
Partner: UNT Libraries Government Documents Department

Neutronic Design Calculations on Moderators for the Spallation Neutron Source (SNS)

Description: The Spallation Neutron Source (SNS) to be built at the Oak Ridge National Laboratory will provide an intense source of neutrons for a large variety of experiments. It consists of a high-energy (1-GeV) and high-power ({approximately}1-MW) proton accelerator, an accumulator ring, together with a target station and an experimental area. In the target itself, the proton beam will produce neutrons via the spallation process and these will be converted to low-energy (<2-eV) neutrons in moderators located close to the target. Current plans are to have two liquid-hydrogen (20-K) moderators and two room-temperature H{sub 2}O moderators. Extensive engineering design work has been conducted on the moderator vessels. For our studies we have produced realistic neutronic representations of these moderators. We report on neutronic studies conducted on these representations of the moderators using Monte Carlo simulation techniques.
Date: November 14, 1999
Creator: Murphy, D.B.
Partner: UNT Libraries Government Documents Department

A preliminary comparative study of the electron-cloud effect for the PSR, ISIS, and the ESS

Description: We present preliminary electron-cloud simulation results for the Proton Storage Ring (PSR) at LANL, ISIS at RAL, and the European Spallation Source (ESS). For each storage ring, we simulate the build-up and dissipation of the electron cloud (EC) in a representative field-free section of the vacuum chamber. For all three cases, we choose the same residual gas temperature, secondary emission yield (SEY), and secondary emission spectrum. Other variables such as proton loss rate, bunch profile, intensity and energy, residual gas pressure and chamber geometry, are set at the corresponding values for each machine. Under these assumptions, we conclude that, of the three machines, the PSR is the most severely affected by the electron cloud effect (ECE), followed by the ESS, with ISIS a distant third. We illustrate a strong sensitivity of the ECE to the longitudinal bunch profile by choosing two different shapes for the case of the PSR, and a weak sensitivity to residual gas pressure. This preliminary study does not address the ECE in other regions of the machine, nor the beam instability that might arise from the EC.
Date: June 20, 2003
Creator: Furman, M.A. & Pivi, M.T.F.
Partner: UNT Libraries Government Documents Department

Overview of the NSNS Target Station

Description: The technologies that are being utilized to design and build a state-of-the-art neutron spallation source, the National Spallation Neutron Source (NSNS), are discussed. Emphasis is given to the technology issues that present the greatest scientific challenges. The present facility configuration, ongoing analysis and the planned hardware research and development program are also described.
Date: August 2001
Creator: Gabriel, T. A.
Partner: UNT Libraries Government Documents Department

Utilization of Monte Carlo Calculations in Radiation Transport Analyses to Support the Design of the U.S. Spallation Neutron Source (SNS)

Description: The Department of Energy (DOE) has given the Spallation Neutron Source (SNS) project approval to begin Title I design of the proposed facility to be built at Oak Ridge National Laboratory (ORNL) and construction is scheduled to commence in FY01 . The SNS initially will consist of an accelerator system capable of delivering an {approximately}0.5 microsecond pulse of 1 GeV protons, at a 60 Hz frequency, with 1 MW of beam power, into a single target station. The SNS will eventually be upgraded to a 2 MW facility with two target stations (a 60 Hz station and a 10 Hz station). The radiation transport analysis, which includes the neutronic, shielding, activation, and safety analyses, is critical to the design of an intense high-energy accelerator facility like the proposed SNS, and the Monte Carlo method is the cornerstone of the radiation transport analyses.
Date: October 23, 2000
Creator: Johnson, J.O.
Partner: UNT Libraries Government Documents Department

Pre-Conceptual Design and Preliminary Neutronic Analysis of the Proposed National Spallation Neutron Source (NSNS)

Description: The Department of Energy (DOE) has initiated a pre-conceptual design study for the National Spallation Neutron Source (NSNS) and given preliminary approval for the proposed facility to be built at Oak Ridge National Laboratory (ORNL). The pre-conceptual design of the NSNS initially consists of an accelerator system capable of delivering a 1 to 2 GeV proton beam with 1 MW of beam power in an approximate 0.5 {micro}s pulse at a 60 Hz frequency onto a single target station. The NSNS will be upgradable to a significantly higher power level with two target stations (a 60 Hz station and a 10 Hz station). There are many possible layouts and designs for the NSNS target stations. This paper gives a brief overview of the proposed NSNS with respect to the target station, as well as the general philosophy adopted for the neutronic design of the NSNS target stations. A reference design is presented, and some preliminary neutronic results for the NSNS are briefly discussed.
Date: August 1, 2001
Creator: Johnson, JO
Partner: UNT Libraries Government Documents Department

Target Station Development for the National Spallation Neutron Source

Description: The technologies that are being utilized to design and build a state-of-the-art neutron spallation source, the National Spallation Neutron Source (NSNS), are discussed. Emphasis is given to the technology issues that present the greatest scientific challenges. The present facility configuration, ongoing analysis and the planned hardware research and development program are also described.
Date: August 1, 2001
Creator: Gabriel, TA
Partner: UNT Libraries Government Documents Department

Slow Neutron Leakage Spectra from Spallation Neutron Sources

Description: An efficient technique is described for Monte Carlo simulation of neutron beam spectra from target-moderator-reflector assemblies typical of pulsed spallation neutron sources. The technique involves the scoring of the transport-theoretical probability that a neutron will emerge from the moderator surface in the direction of interest, at each collision. An angle-biasing probability is also introduced which further enhances efficiency in simple problems.
Date: February 1980
Creator: Das, Shashikala G.; Carpenter, J. M. & Prael, R. E.
Partner: UNT Libraries Government Documents Department