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Optimal design of high speed analog APD receivers

Description: In order to provide optical to electrical conversion of high speed analog signals, avalanche photodiode receivers must be optimized for several parameters. Among these parameters are receiver amplifier noise, APD noise, and bandwidth. Optimization of these parameters requires a theoretical understanding of each of the parameters and their interactions. In the first part of this paper the theoretical design of an avalanche photodiode optical receiver will be discussed with attention to the parameters mentioned. Later, a comparison between calculated and measured values for a receiver design will be presented. 6 refs., 3 figs.
Date: January 1, 1988
Creator: Smith, R.C.
Partner: UNT Libraries Government Documents Department

Reduction and Stabilization of Plutonium Nitrate in Cation Exchange Feed and Product Solutions

Description: In the conceutration and purification of Pu by cation exchange, the feed solution must be in the plus three valence state, but the nitrate solution from a solvent extraction process contains a high% of Pu/sup 4+/ and a small amount of Pu/sup 6+/. It was desired to find a reducing agent satisfactory for the reduction of Pu/sup 4+/ and Pu/sup 6+/ in Purex product streams and to make these streams suitable as cation exchange feed. The bisulfates met the requirements for speed and completeness of reduction in the feed material. (J.E.D.)
Date: September 24, 1957
Creator: Brunstad, A. & Smith, R. C.
Partner: UNT Libraries Government Documents Department

Tissue equivalent proportional counter neutron monitor

Description: The Tissue Equivalent Proportional Counter (TEPC) is a sensitive area monitoring instrument that can be used either in place at fixed locations or as a portable neutron exposure measuring device. The system monitors low levels of neutron radiation exposure and has the capability of accurately measuring neutron exposure rates as low as 0.1 mrem/hr. The computerized analysis system calculates the quality factor which is important for situations where the neutron to gamma ratio may vary significantly and irregularly such as in fuel fabrication or handling facilities.
Date: June 1, 1980
Creator: Smith, R.C. & Strode, J.N.
Partner: UNT Libraries Government Documents Department

SSC high speed communication channel and interconnects

Description: This paper investigates potential metallic and optical technology applications in SSC high speed interconnects and/or communication channels. Primary focus will be placed on evaluating several metallic and optical interconnect structures. 7 refs., 3 figs.
Date: January 1, 1990
Creator: Cooke, B.J.; Smith, R.C. & Wagner, R.
Partner: UNT Libraries Government Documents Department

PWR shutdown decay-heat removal analyses in support of TAP A-45. [Feed and bleed]

Description: The US NRC currently considers the adequacy of shutdown decay heat removal to be an unresolved safety issue (USI A-45). The purpose of Task Action Plan (TAP) A-45 is to evaluate the adequacy of current licensing design requirements, to ensure that nuclear power plants do not pose an unacceptable risk because of failure to remove shutdown decay heat. A major part of TAP A-45 is concerned with the transition from reactor trip to hot shutdown. Also of interest is the transition from hot shutdown to cold shutdown and maintaining cold shutdown conditions. Although a limited number of alternative means for removal of shutdown decay heat from PWRs are being examined by the NRC, this paper focuses on the application of the feed and bleed concept as a diverse alternative method of removing decay heat that does not rely on the use of the steam generators.
Date: January 1, 1983
Creator: Boyack, B.E.; Henninger, R.J. & Smith, R.C.
Partner: UNT Libraries Government Documents Department

Multigigahertz beam diagnostics for laser fusion

Description: A system to make ultra wideband measurements of fast laser pulses and their induced target interactions at a distance of approximately 38 m from the target location is discussed. The system has demonstrated an overall bandwidth of 3 GHz with projected unfolding to 4 GHz. This system allows high resolution temporal history diagnostics in a remote location providing high EMI and radiation immunity.
Date: January 1, 1981
Creator: Smith, R.C.; Hodson, E.K. & Carlson, R.L.
Partner: UNT Libraries Government Documents Department

TRAC-PF1 analyses of potential pressurized-thermal-shock transients at a Combustion-Engineering PWR. [Overcooling]

Description: Los Alamos is participating in a program to assess the risk of pressurized thermal shock (PTS) to a reactor vessel. Our role is to provide best-estimate thermal-hydraulic analyses of 12 postulated overcooling transients using TRAC-PF1. These transients are hypothetical and include multiple operator/equipment failures. Calvert Cliffs/Unit-1, a Combustion-Engineering plant, is the pressurized water reactor modeled for this study. The utility and the vendor supplied information for the comprehensive TRAC-PF1 model. Secondary and primary breaks from both hot-zero-power and full-power conditions were simulated for 7200 s (2 h). Low bulk temperatures and loop-flow stagnation while the system was at a high pressure were of particular interest for PTS analysis. Three transients produced primary temperatures below 405 K (270/sup 0/F - the NRC screening criterion) with system repressurization. Six transients indicated flow stagnation would occur in one loop but not both. One transient showed flow stagnation might occur in both loops. Oak Ridge National Laboratory will do fracture-mechanics analysis using these TRAC-PF1 results and make the final determination of the risk of PTS.
Date: January 1, 1984
Creator: Koenig, J.E.; Spriggs, G.D. & Smith, R.C.
Partner: UNT Libraries Government Documents Department

MANHATTAN DISTRICT HISTORY PROJECT Y THE LOS ALAMOS PROJECT VOL. II AUGUST 1945 THROUGH DECEMBER 1946

Description: THESE TWO VOLUMES CONSTITUTE A RECORD OF THE TECHNICAL, ADMINISTRATIVE , AND POLICY-MAKING ACTIVITIES OF THE LOS ALAMOS PROJECT (PROJECT Y) FROM ITS INCEPTION UNDER THE MANHATTAN DISTRICT THROUGH THE DEVELOPMENT OF THE ATOMIC BOMB (VOL. I), AND DURING THE PERIOD FOLLOWING THE END OF WORLD WAR II UNTIL THE MANHATTAN DISTRICT RELINQUISHED CONTROL TO THE ATOMIC ENERGY COMMISSION AS OF JANUARY 1947 (VOL. II). ALTHOUGH SEC URITY REGULATIONS HAVE REQUIRED SOME DELETIONS IN THE ORIGINAL TEXT OF THE TWO VOLUMES, EVERY EFFORT HAS BEEN MADE TO RETAIN THE ORIGINAL LANGUGAGE AND EXPERSSIONS OF THE AUTHORS.
Date: December 1, 1961
Creator: Truslow, E. C. & Smith, R. C.
Partner: UNT Libraries Government Documents Department

DEMONSTRATION OF AN IRRADIATED UO$sub 2$ FUEL RECYCLE: FIRST RECYCLE

Description: Irradiated UO/sub 2/ was processed for recycle by one version of the Salt Cycle Process. The irradiated fuel was dissolved in fused NaCl-KCl and the bulk of the uranium and plutonium were recovered as UO/sub 2/ and PuO/sub 2/ by elcctrodeposition. A reduction in the concentration of fission product poisons in the fuel was also achieved in the electrodeposition step. Fabrication of the partially decontaminated, irradiated UO/sub 2/ into a fuel rod and subsequent incorporation of the fuel rod into a four-rod cluster fuel element was accomplished by remote handling techniques. Two rods of the cluster contained nonrecycled, electrodeposited UO/sub 2/, one contained sintered UO/sub 2/ pellets, and the fourth contained the recycled, electrodeposited UO/sub 2/. The element was irradiated in the MTR with a maximum surface heat flux of approximately 300,000 Btu/(hr)(sq ft) to an exposure of approximately 450 MWD/T. The fuel rods containing electrodeposited UO/sub 2/ (both recycled and nonrecycled) suffered no adverse effects during irradiation. (auth)
Date: September 1, 1961
Creator: Swanson, J L; Benedict, G E; Smith, R C & Horn, G R
Partner: UNT Libraries Government Documents Department

Sub-100 ps bulk-recombination-limited InP:Fe photoconductive detector

Description: Both surface and bulk excited semi-insulating InP optoelectronic switches were studied. It was found that transient recombination in these devices is the same for both types of excitation. It is concluded that the recombination is a bulk controlled process.
Date: January 1, 1981
Creator: Hammond, R.B.; Paulter, N.G.; Iverson, A.E. & Smith, R.C.
Partner: UNT Libraries Government Documents Department

100 MHz fiber optic single transient gamma ray detection system

Description: A fiber optic system has been developed to measure single transient gamma rays. The gamma ray signature is converted to light by the Cerenkov process in a 20 cm length of radiation resistant optical fiber. The signal is transmitted over 1 km of optical fiber and detected by state-of-the-art, 175 MHz analog receivers. The receivers are based on silicon PIN detectors with transimpedance hybrid amplifiers and two stages of power amplification. The dc coupled receivers have less than 2% distortion up to 5 volts with less than 10 mV rms noise and a responsivity of 37,500 V/watt at 800 nm. A calibration system measures relative fiber to fiber transit time delays and ''system'' sensitivity. System bandwidth measurements utilized an electron linear accelerator (Linac) with a 50 ps electron pulse as the Cerenkov light source. The system will be described with supporting calibrationa and characterization data of parts of the system and the whole system.
Date: January 1, 1984
Creator: Ogle, J.W.; Smith, R.C.; Ward, M.; Ramsey, R. & Hollabaugh, J.
Partner: UNT Libraries Government Documents Department

Tissue equivalent proportional counter real time neutron monitor

Description: The Tissue Equivalent Proportional Counter (TEPC) was developed to monitor low level neutron exposure rates at working stations in a nuclear fuel fabrication facility. It has proven capable of accurately measuring neutron dose rates at levels from 0.1 to 0.2 mrem/hr. It also calculates the Quality Factor which is of importance in locations where the neutron to gamma ratio may vary significantly and irregularily. The system described is computerized to monitor 100 work locations simulationeously and can be expanded to monitor 384 locations. Neutron dose is accumulated on a real time basis and after the proton drop point is established, dose rate can be read out at any time for the dose accumulated over a specified period of time. The current development program which provides reduced system maintenance, lower detection limits, and improved accuracy is discussed along with examples of measurement data and work experience with the current system.
Date: January 1, 1978
Creator: Smith, R. C.; Strode, J. N.; Brackenbush, L. W. & Faust, L. G.
Partner: UNT Libraries Government Documents Department

A 100 ps gated x-ray spectrometer

Description: Material opacities are of interest in many fields. We have developed a Bragg reflection spectrometer that is gated for imaging samples in a laser heated environment for opacity measurement. A micro-channel plate is coated with a photocathode material and a fast pulse is launched across it. Electrons are converted to photons in a phosphor and recorded on film. Optical gate pulse widths of 100 ps are achieved. Some optical pulse width and sensitivity enhancements are noted at launch and termination. Events of interest are 200 ps long. The framing window is approximately 250 ps in length. Timing jitter is a problem. The instrument timing networks have been examined, and the source of jitter is still unknown. Timing to 50 ps resolution is desired. Close in proximity to the laser-driven event leads to complications in shielding from hard x-rays, hot electrons and shock-driven damage. High Z materials provide shielding from hard x-rays. Magnets screen out hot electrons produced by laser-matter interactions Filters provide energy fiducials. PCD`s provide high resolution timing measurements. Data is recorded on film in a specially designed film pack. The instrument is designed to be used in the NOVA Laser Facility at Lawrence Livermore National Laboratory.
Date: September 1, 1995
Creator: Walsh, P.J.; Blake, R.L.; Caldwell, S.; Hockaday, M.; Chrien, R. & Smith, R.C.
Partner: UNT Libraries Government Documents Department

MELCOR 1.8.2 assessment: Surry PWR TMLB` (with a DCH study)

Description: MELCOR is a fully integrated, engineering-level computer code, being developed at Sandia National Laboratories for the USNRC. This code models the entire spectrum of severe accident phenomena in a unified framework for both BWRs and PWRs. As part of an ongoing assessment program, the MELCOR computer code has been used to analyze a station blackout transient in Surry, a three-loop Westinghouse PWR. Basecase results obtained with MELCOR 1.8.2 are presented, and compared to earlier results for the same transient calculated using MELCOR 1.8.1. The effects of new models added in MELCOR 1.8.2 (in particular, hydrodynamic interfacial momentum exchange, core debris radial relocation and core material eutectics, CORSOR-Booth fission product release, high-pressure melt ejection and direct containment heating) are investigated individually in sensitivity studies. The progress in reducing numeric effects in MELCOR 1.8.2, compared to MELCOR 1.8.1, is evaluated in both machine-dependency and time-step studies; some remaining sources of numeric dependencies (valve cycling, material relocation and hydrogen burn) are identified.
Date: February 1, 1994
Creator: Kmetyk, L.N.; Cole, R.K. Jr.; Smith, R.C.; Summers, R.M. & Thompson, S.L.
Partner: UNT Libraries Government Documents Department

Echoes from Ancient supernovae in the Large Magellanic Cloud

Description: In principle, historical supernovae could still be visible as scattered-light echoes even centuries later [1, 2]. Searches for surface brightness variations using photographic plates have not recovered any echoes in the regions of historical Galactic supernovae [3]. Using differenced images, our SuperMACHO collaboration has discovered three faint new variable surface brightness complexes with high apparent proper motion pointing back to well-defined positions in the Large Magellanic Cloud (LMC). These correspond to three of the six smallest (and likely youngest) supernova remnants believed to be due to thermonuclear (Type Ia) supernovae [4]. A lower limit to the age of these remnants and echoes is 200 years given the lack of any reported LMC supernovae until 1987. The discovery of historical supernova echoes in the LMC suggests that similar echoes for Galactic supernovae such as Tycho, Kepler, Cas A, or SN1006 could be visible using standard image differencing techniques.
Date: June 15, 2005
Creator: Rest, A; Suntzeff, N B; Olsen, K; Prieto, J L; Smith, R C; Welch, D L et al.
Partner: UNT Libraries Government Documents Department

Progress in MELCOR development and assessment

Description: MELCOR models the progression of severe accidents in light water reactor nuclear power plants. Recent efforts in MELCOR development to incorporate CORCON-Mod3 models for core-concrete interactions, new models for advanced reactors, and improvements to several other existing models have resulted in release of MELCOR 1.8.3. In addition, continuing efforts to expand the code assessment database have filled in many of the gaps in phenomenological coverage. Efforts are now under way to develop models for chemical interactions of fission products with structural surfaces and for reactions of iodine in the presence of water, and work is also in progress to improve models for the scrubbing of fission products by water pools, the chemical reactions of boron carbide with steam, and the coupling of flow blockages with the hydrodynamics. Several code assessment analyses are in progress, and more are planned.
Date: April 1, 1995
Creator: Summers, R. M.; Kmetyk, L. N.; Cole, R. K., Jr.; Smith, R. C.; Elsbernd, A. E.; Stuart, D. S. et al.
Partner: UNT Libraries Government Documents Department

MELCOR computer code manuals

Description: MELCOR is a fully integrated, engineering-level computer code that models the progression of severe accidents in light water reactor nuclear power plants. MELCOR is being developed at Sandia National Laboratories for the U.S. Nuclear Regulatory Commission as a second-generation plant risk assessment tool and the successor to the Source Term Code Package. A broad spectrum of severe accident phenomena in both boiling and pressurized water reactors is treated in MELCOR in a unified framework. These include: thermal-hydraulic response in the reactor coolant system, reactor cavity, containment, and confinement buildings; core heatup, degradation, and relocation; core-concrete attack; hydrogen production, transport, and combustion; fission product release and transport; and the impact of engineered safety features on thermal-hydraulic and radionuclide behavior. Current uses of MELCOR include estimation of severe accident source terms and their sensitivities and uncertainties in a variety of applications. This publication of the MELCOR computer code manuals corresponds to MELCOR 1.8.3, released to users in August, 1994. Volume 1 contains a primer that describes MELCOR`s phenomenological scope, organization (by package), and documentation. The remainder of Volume 1 contains the MELCOR Users Guides, which provide the input instructions and guidelines for each package. Volume 2 contains the MELCOR Reference Manuals, which describe the phenomenological models that have been implemented in each package.
Date: March 1, 1995
Creator: Summers, R.M.; Cole, R.K. Jr.; Smith, R.C.; Stuart, D.S.; Thompson, S.L.; Hodge, S.A. et al.
Partner: UNT Libraries Government Documents Department

MELCOR computer code manuals: Primer and user`s guides, Version 1.8.3 September 1994. Volume 1

Description: MELCOR is a fully integrated, engineering-level computer code that models the progression of severe accidents in light water reactor nuclear power plants. MELCOR is being developed at Sandia National Laboratories for the US Nuclear Regulatory Commission as a second-generation plant risk assessment tool and the successor to the Source Term Code Package. A broad spectrum of severe accident phenomena in both boiling and pressurized water reactors is treated in MELCOR in a unified framework. These include: thermal-hydraulic response in the reactor coolant system, reactor cavity, containment, and confinement buildings; core heatup, degradation, and relocation; core-concrete attack; hydrogen production, transport, and combustion; fission product release and transport; and the impact of engineered safety features on thermal-hydraulic and radionuclide behavior. Current uses of MELCOR include estimation of severe accident source terms and their sensitivities and uncertainties in a variety of applications. This publication of the MELCOR computer code manuals corresponds to MELCOR 1.8.3, released to users in August, 1994. Volume 1 contains a primer that describes MELCOR`s phenomenological scope, organization (by package), and documentation. The remainder of Volume 1 contains the MELCOR Users` Guides, which provide the input instructions and guidelines for each package. Volume 2 contains the MELCOR Reference Manuals, which describe the phenomenological models that have been implemented in each package.
Date: March 1, 1995
Creator: Summers, R. M.; Cole, R. K., Jr.; Smith, R. C.; Stuart, D. S.; Thompson, S. L.; Hodge, S. A. et al.
Partner: UNT Libraries Government Documents Department