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Evaluation of photoneutron production at high energy LINACS

Description: This report describes an estimate of neutron production at a 9 MeV LINAC, and the potential for photoactivation of materials present at the LINAC facility. It was found that only isotopes of U, W, Ta, and Pb had daughters whose activities might be measurable. The LINAC was found to be capable of producing in the neighborhood of 10{sup 10} neutrons/second from these heavy metals, and that subsequent neutron activation might be more of a concern. Monte Carlo simulation of neutron transport and capture in the concrete and steel found in the LINAC vault indicates that {sup 55}Fe may be produced in measurable quantities.
Date: April 24, 1995
Creator: Bell, Z.W.
Partner: UNT Libraries Government Documents Department

Fabric composite radiators for space nuclear power applications. Final report, March 1993

Description: Nuclear power systems will be required to provide much greater power levels for both civilian and defense space activities in the future than an currently needed. Limitations on the amount of usable power from radioisotope thermal generators and the limited availability of radioisotope heat source materials lead directly to the conclusion that nuclear power reactors will be needed to enhance the exploration of the solar system as well as to provide for an adequate defense. Lunar bases and travel to the Martian surface will be greatly enhanced by the use of high levels of nuclear power. Space based radar systems requiring many kilowatts of electrical power can provide intercontinental airline traffic control and defense early warning systems. Since the, figure of merit used in defining any space power system is the specific power, the decrease in die mass of any reactor system component will yield a tremendous benefit to the overall system performance. Also, since the heat rejection system of any power system can make up a large portion of the total system mass, any reduction in the mass of the heat rejection radiators will significantly affect the performance of the power system. Composite materials which combine the high strength, flexibility, and low mass characteristics of Si% based fibers with the attractive compatibility and heat transfer features of metallic foils, have been proposed for use m a number of space radiator applications. Thus, the weave of the fabric and the high strength capability of the individual fibers are combined with the high conductivity and chemical stability of a metallic liner to provide a light weight, flexible alternative to heavy, rigid, metallic radiator structural containers. The primary focus of this investigation revolves around two applications of the fabric composite materials, notably a fabric heat pipe radiator design and the Bubble Membrane ...
Date: March 24, 1993
Creator: Klein, A.C.; Al-Baroudi, H.; Gulshan-Ara, Z.; Kiestler, W.C.; Snuggerud, R.D.; Abdul-Hamid, S.A. et al.
Partner: UNT Libraries Government Documents Department

Inversion of Passive Electromagnetic Fields to Locate Weapons of Mass Destruction

Description: A resolution study, employing a 3D nonlinear optimization technique, has been undertaken to study the viability of magnetotelluric (MT) measurements to detect and characterize buried facilities that make weapons of mass destruction. A significant advantage of the MT method is that no active source is required because the method employs passive field emissions. Thus measurements can be carried out covertly. Findings indicate it is possible to image WMD facilities, including depth of burial and lateral extent if a sufficient number of measurements are taken on the perimeter of the facility. Moreover if a station measurement can be made directly over the facility then the resolution is improved accordingly. In all cases it was not possible to image the base of the facility with any confidence as well as provide any precise inferences on the facility electrical conductivity. This later finding, however, is really not that critical since knowledge of facility geometry is far more important than knowledge of its conductivity. For the WMD problem it is recommended that MT measurements be made solely with the magnetic field ratios. In this context it would then be possible to deploy with far greater ease small coils about a suspected facility and would allow for the measurements to be conducted in a more covert manner. Before testing such a measurement system in the field, however, it would be necessary to carry out a similar resolution analysis as was done with MT measurements based on electric and magnetic fields. This is necessary to determine sensitivity of the proposed measurement to underground facilities along with needed data coverage and quality. Such a study is indispensable in producing useful reconstructions of underground facilities.
Date: December 24, 1998
Creator: Day, D.M. & Newman, G.A.
Partner: UNT Libraries Government Documents Department

Variations in the Nature of Metal Adsorption on Ultrathin Al(2)O(3) Films

Description: First-principles density-functional calculations are used to study metal adsorption (Li, K, Y, Nb, Ru, Pd, Pt, Cu, Ag, Au, and Al at 1/3-4 monolayer coverages) atop 5 ~ A1203 films on Al(Ill). The oxide-metal bond is ionic at Iow coverages but, with interesting exceptions, caused by polari@i ,~-cE!vED at high coverages where the overlayer is metallic. Binding trends are explained in terms of s'imp e concepts. Increasing overlayer thickness can cause the adsorbate-oxide interface structure to than . %lEc o ~ 1998 and while some metals wet, most do not.
Date: November 24, 1998
Creator: Bogicevic, A. & Jennison, D.R.
Partner: UNT Libraries Government Documents Department

High priority tank sampling and analysis report

Description: In July 1993, the Defense Nuclear Facilities Board issued Recommendation 93-5 (Conway 1993) which noted that there was insufficient tank waste technical information and the pace to obtain it was too slow to ensure that Hanford Site wastes could be safely stored, that associated operations could be conducted safely, and that future disposal data requirements could be met. In response, the US Department of Energy, in May 1996, issued Revision 1 of the Recommendation 93-5 Implementation Plan (DOE-RL 1996). The Implementation Plan presented a modified approach to achieve the original plan`s objectives, concentrating on actions necessary to ensure that wastes can be safely stored, that operations can be safely conducted, and that timely characterization information for the tank waste Disposal Program could be obtained. The Implementation Plan proposed 28 High Priority tanks for near term core sampling and analysis, which along with sampling and analysis of other non-High Priority tanks, could provide the scientific and technical data to confirm assumptions, calibrate models, and.measure safety related phenomenology of the waste. When the analysis results of the High Priority and other-tank sampling were reviewed, it was expected that a series of 12 questions, 9 related to safety issues and 3 related to planning for the disposal process, should be answered allowing key decisions to be made. This report discusses the execution of the Implementation Plan and the results achieved in addressing the questions. Through sampling and analysis, all nine safety related questions have been answered and extensive data for the three disposal planning related questions have been collected, allowing for key decision making. Many more tanks than the original 28 High Priority tanks identified in the Implementation Plan were sampled and analyzed. Twenty-one High Priority tanks and 85 other tanks were core sampled and used to address the questions. Thirty-eight additional tanks ...
Date: March 24, 1998
Creator: Brown, T.M.
Partner: UNT Libraries Government Documents Department

Environmental Effects in Advanced Intermetallics

Description: This paper provides a comprehensive review of environmental embrittlement in iron and nickel aluminizes. The embrittlement involves the interaction of these intermetallics with moisture in air and generation of atomic hydrogen, resulting in hydrogen-induced embrittlement at ambient temperatures. Environmental embrittlement promotes brittle grain-boundary fracture in Ni{sub 3}Al alloys but brittle cleavage fracture in Fe{sub 3}Al-FeAl alloys. The embrittlement strongly depends on strain rate, with tensile-ductility increase with increasing strain rate. It has been demonstrated that environmental embrittlement can be alleviated by alloying additions, surface modifications, and control of grain size and shape. Boron tends to segregate strongly to grain boundaries and is most effective in suppressing environmental embrittlement in Ni{sub 3}Al alloys. The mechanistic understanding of alloy effects and environmental embrittlement has led to the development of nickel and iron aluminide alloys with improved properties for structural use at elevated temperatures in hostile environments.
Date: November 24, 1998
Creator: Liu, C.T.
Partner: UNT Libraries Government Documents Department

COMSORS: A light water reactor chemical core catcher

Description: The Core-Melt Source Reduction System (COMSORS) is a new approach to terminate lightwater reactor (LWR) core-melt accidents and ensure containment integrity. A special dissolution glass made of lead oxide (PbO) and boron oxide (B{sub 2}O{sub 3}) is placed under the reactor vessel. If molten core debris is released onto the glass, the following sequence happens: (1) the glass absorbs decay heat as its temperature increases and the glass softens; (2) the core debris dissolves into the molten glass; (3) molten glass convective currents create a homogeneous high-level waste (HLW) glass; (4) the molten glass spreads into a wider pool, distributing the heat for removal by radiation to the reactor cavity above or transfer to water on top of the molten glass; and (5) the glass solidifies as increased surface cooling area and decreasing radioactive decay heat generation allows heat removal to exceed heat generation.
Date: February 24, 1997
Creator: Forsberg, C.W.; Parker, G.W.; Rudolph, J.C.; Osborne-Lee, I.W. & Kenton, M.A.
Partner: UNT Libraries Government Documents Department

Determination of the solubility of Np(IV), Pu(III) - (VI),Am(III) - (VI), and Te(IV), (V) hydroxo compounds in 0.5 - 14 M NaOH solutions

Description: The solubilities of Am(III), Np(IV), Pu(IV), Tc(IV), Np(V), Pu(V), Am(V), and Tc(V) hydroxo compounds were studied in 0.5 to 14 M NaOH solutions at 25{+-}2 {degrees}C. The effects of fluoride, phosphate, carbonate, oxalate, and some other organic complexing agents on the solubilities of Np(IV), Pu(IV), and TC(IV) hydroxides were investigated at 1.0 and 4.0 M NAOH. Some predictions were made on the dissolved (I.V) and (V) species present in alkali solutions.
Date: September 24, 1996
Creator: Delegard, C.H.
Partner: UNT Libraries Government Documents Department

Advanced Oil Recovery Technologies for Improved Recovery from Slope Basin Clastic Reservoirs, Nash Draw Brushy Canyon Pool, Eddy County, NM

Description: The Nash Draw Brushy Canyon Pool in Eddy County New Mexico is a cost-shared field demonstration project in the US Department of Energy Class II Program. A major goal of the Class III Program is to stimulate the use of advanced technologies to increase ultimate recovery from slope-basin clastic reservoirs. Advanced characterization techniques are being used at the Nash Draw project to develop reservoir management strategies for optimizing oil recovery from this Delaware reservoir. Analysis, interpretation, and integration of recently acquired geologic, geophysical, and engineering data revealed that the initial reservoir characterization was too simplistic to capture the critical features of this complex formation. Contrary to the initial characterization, a new reservoir description evolved that provided sufficient detail regarding the complexity of the Brushy Canyon interval at Nash Draw. This new reservoir description is being used as a risk reduction tool to identify ''sweet spots'' for a development drilling program as well as to evaluate pressure maintenance strategies. The reservoir characterization, geological modeling, 3-D seismic interpretation, and simulation studies have provided a detailed model of the Brushy Canyon zones. This model was used to predict the success of different reservoir management scenarios and to aid in determining the most favorable combination of targeted drilling, pressure maintenance, well simulation, and well spacing to improve recovery from this reservoir.
Date: February 24, 1999
Creator: Murphy, Mark B.
Partner: UNT Libraries Government Documents Department

The Heisenberg representation of quantum computers

Description: Since Shor`s discovery of an algorithm to factor numbers on a quantum computer in polynomial time, quantum computation has become a subject of immense interest. Unfortunately, one of the key features of quantum computers--the difficulty of describing them on classical computers--also makes it difficult to describe and understand precisely what can be done with them. A formalism describing the evolution of operators rather than states has proven extremely fruitful in understanding an important class of quantum operations. States used in error correction and certain communication protocols can be described by their stabilizer, a group of tensor products of Pauli matrices. Even this simple group structure is sufficient to allow a rich range of quantum effects, although it falls short of the full power of quantum computation.
Date: June 24, 1998
Creator: Gottesman, D.
Partner: UNT Libraries Government Documents Department

Surface contamination initiated laser damage

Description: We are engaged in a comprehensive effort to understand and model the initiation and growth of laser damage initiated by surface contaminants. This includes, for example, the initial absorption by the contaminant, heating and plasma generation, pressure and thermal loading of the transparent substrate, and subsequent shockwave propagation, ``splashing`` of molten material and possible spallation, optical propagation and scattering, and treatment of material fracture. The integration use of large radiation hydrodynamics codes, optical propagation codes and material strength codes enables a comprehensive view of the damage process The following picture of surface contaminant initiated laser damage is emerging from our simulations. On the entrance optical surface, small particles can ablate nearly completely. In this case, only relatively weak shockwaves are launched into the substrate, but some particulate material may be left on the surface to act as a diffraction mask and cause further absorption. Diffraction by wavelength scale scattering centers can lead to significant intensity modulation. Larger particles will not be completely vaporized. The shockwave generated in this case 1642is larger and can lead to spallation of contaminant material which then may be deposited in the substrate. A gaseous atmosphere can lead to radiation trapping with concomitant increases in temperature and pressure near the surface. In addition, supersonic ionization waves in air may be generated which greatly extend the plasma plume spatially and temporally. Contaminants on the exit optical surface behave differently. They tend to heat and pop off completely in which case significant damage may not occur. Since plasma formed at the interface of the optic and absorbing particle is confined, much stronger pressures are generated in this case. Imaging of contaminants resulting in ``writing`` a diffraction pattern on the exit surface due to contamination on the entrance surface has been observed experimentally and predicted theoretically. Such imprinted damage ...
Date: January 24, 1997
Creator: Feit, M.D.; Rubenchick, A.M. & Faux, D.R.
Partner: UNT Libraries Government Documents Department

The Synergism Between Heat and Mass Transfer Additive and Advanced Surfaces in Aqueous LiBr Horizontal Tube Absorbers

Description: Experiments were conducted in a laboratory to investigate the absorption of water vapor into a falling-film of aqueous lithium bromide (LiBr). A mini-absorber test stand was used to test smooth tubes and a variety of advanced tube surfaces placed horizontally in a single-row bundle. The bundle had six copper tubes; each tube had an outside diameter of 15.9-mm and a length of 0.32-m. A unique feature of the stand is its ability to operate continuously and support testing of LiBr brine at mass fractions {ge} 0.62. The test stand can also support testing to study the effect of the failing film mass flow rate, the coolant mass flow rate, the coolant temperature, the absorber pressure and the tube spacing. Manufacturers of absorption chillers add small quantities of a heat and mass transfer additive to improve the performance of the absorbers. The additive causes surface stirring which enhances the transport of absorbate into the bulk of the film. Absorption may also be enhanced with advanced tube surfaces that mechanically induce secondary flows in the falling film without increasing the thickness of the film. Several tube geometry's were identified and tested with the intent of mixing the film and renewing the interface with fresh solution from the tube wall. Testing was completed on a smooth tube and several different externally enhanced tube surfaces. Experiments were conducted over the operating conditions of 6.5 mm Hg absorber pressure, coolant temperatures ranging from 20 to 35 C and LiBr mass fractions ranging from 0.60 through 0.62. Initially the effect of tube spacing was investigated for the smooth tube surface, tested with no heat and mass transfer additive. Test results showed the absorber load and the mass absorbed increased as the tube spacing increased because of the improved wetting of the tube bundle. However, tube spacing ...
Date: March 24, 1999
Creator: Miller, W.A.
Partner: UNT Libraries Government Documents Department

Accruals for HANDI 2000 business management system

Description: The Data Integration 2000 Project will result in an integrated and comprehensive set of functional applications containing core information necessary to support the Project Hanford Management Contract. It is based on the Commercial-Off-The-Shelf product solution with commercially proven business processes. The COTS product solution set, of PassPort and People Soft software, supports finance, supply and chemical management/Material Safety Data Sheet, human resources. Accruals are made at the project level. At the inception of each project, Project Management and the Accounts Payable Group make a mutual decision on whether periodic accrual entries should be made for it.
Date: August 24, 1998
Creator: Wilson, D.
Partner: UNT Libraries Government Documents Department

Magnetic excitations in a random exchange system Fe{sub x}Mn{sub 1-x}TiO{sub 3}

Description: In order to examine the influence of exchange frustration on spin wave excitations, inelastic neutron scattering experiments have been performed on a random exchange system Fe{sub x}Mn{sub l-x}TiO{sub 3} with x = 0.00, 0.10, 0.25 and 0.33. For all three mixed systems, the magnetic excitation spectra consist of two components: a well-defined spin wave component and a broad damped component. The latter can be well fitted to a spectral weight function for a damped harmonic oscillator.
Date: August 24, 1994
Creator: Kawano, H.; Yoshizawa, H.; Nicklow, R.M. & Ito, A.
Partner: UNT Libraries Government Documents Department

Analysis of PEM electrolyzers

Description: Hydrogen and oxygen can be produced using a PEM electrolyzer. A PEM electrolyzer operates like a fuel cell in reverse. On the anode side of the electrolyzer, electrons are removed from water to form protons and oxygen molecules. The protons are then transported across the membrane. The protons then rejoin with electrons to form hydrogen molecules. In this way water is electrolyzed. In automobiles, the majority of pollutant emissions occur during the start-up of the vehicle. In order to reduce these harmful emissions, a burner will be placed at the end of process to burn off the hydrocarbon emissions. However, this burner must also be hot to completely burn the harmful pollutants. One method of heating this burner quickly is to burn hydrogen before start-up. The burning of the hydrogen will not produce any pollutants. The only products of hydrogen combustion are water and heat. For this reason, a theoretical design of an electrolyzer/burner system was developed.
Date: July 24, 1998
Creator: Knobbe, M.W.
Partner: UNT Libraries Government Documents Department

Tank 241-T-204, core 188 analytical results for the final report

Description: TANK 241-T-204, CORE 188, ANALYTICAL RESULTS FOR THE FINAL REPORT. This document is the final laboratory report for Tank 241 -T-204. Push mode core segments were removed from Riser 3 between March 27, 1997, and April 11, 1997. Segments were received and extruded at 222-8 Laboratory. Analyses were performed in accordance with Tank 241-T-204 Push Mode Core Sampling and analysis Plan (TRAP) (Winkleman, 1997), Letter of instruction for Core Sample Analysis of Tanks 241-T-201, 241- T-202, 241-T-203, and 241-T-204 (LAY) (Bell, 1997), and Safety Screening Data Qual@ Objective (DO) ODukelow, et al., 1995). None of the subsamples submitted for total alpha activity (AT) or differential scanning calorimetry (DC) analyses exceeded the notification limits stated in DO. The statistical results of the 95% confidence interval on the mean calculations are provided by the Tank Waste Remediation Systems Technical Basis Group and are not considered in this report.
Date: July 24, 1997
Creator: Nuzum, J.L.
Partner: UNT Libraries Government Documents Department

Statistical Analyses of Scatterplots to Identify Important Factors in Large-Scale Simulations, 1: Review and Comparison of Techniques

Description: The robustness of procedures for identifying patterns in scatterplots generated in Monte Carlo sensitivity analyses is investigated. These procedures are based on attempts to detect increasingly complex patterns in the scatterplots under consideration and involve the identification of (i) linear relationships with correlation coefficients, (ii) monotonic relationships with rank correlation coefficients, (iii) trends in central tendency as defined by means, medians and the Kruskal-Wallis statistic, (iv) trends in variability as defined by variances and interquartile ranges, and (v) deviations from randomness as defined by the chi-square statistic. The following two topics related to the robustness of these procedures are considered for a sequence of example analyses with a large model for two-phase fluid flow: the presence of Type I and Type II errors, and the stability of results obtained with independent Latin hypercube samples. Observations from analysis include: (i) Type I errors are unavoidable, (ii) Type 11errors can occur when inappropriate analysis procedures are used, (iii) physical explanations should always be sought for why statistical procedures identify variables as being important, and (iv) the identification of important variables tends to be stable for independent Latin hypercube samples.
Date: March 24, 1999
Creator: Kleijnen, J.P.C. & Helton, J.C.
Partner: UNT Libraries Government Documents Department

Experiments on the interaction of intense femtosecond radiation with dense plasmas. Final report

Description: An upgraded KrF{sup {asterisk}} (248 nm) system producing a pulse energy of {approximately} 400 mJ, a pulse width of {approximately} 220 fs, and focal intensities above 10{sup 19} W/cm{sup 2}, has been constructed, tested, operated, and used in experimental studies. The spatial morphology of channeled radiation in plasmas has been measured with a spatial resolution of {approximately} 30 {mu}m and damage studies of fused silica indicate that femtosecond (200 - 300 fs) 248 nm radiation has a damage limit not exceeding {approximately} 50 GW/cm{sup 2}, an unfavorably low level. 2 figs.
Date: January 24, 1996
Creator: Rhodes, C. K.
Partner: UNT Libraries Government Documents Department

Electron heat transport in improved confinement discharges in DIII-D

Description: In DIII-D tokamak plasmas with an internal transport barrier (ITB), the comparison of gyrokinetic linear stability (GKS) predictions with experiments in both low and strong negative magnetic shear plasmas provide improved understanding for ion and electron thermal transport within much of the plasma. As previously reported, the region for improved ion transport seems well characterized by the condition OE~B>Y-, where SERB is the ExB flow shear, calculated from measured quantities, and y,, is the maximum linear growth rate for ion temperature gradient (ITG) modes in the absence of flow shear. Within a limited region just inside the ITB, the electron temperature gradient (ETG) modes appear to control the electron temperature gradient and, consequently, the electron thermal transport. The increase in electron temperature gradient with more strongly negative magnetic shear is consistent with the increase in the ETG mode marginal gradient. Closer to the magnetic axis the Te profile flattens and the ETG modes are predicted to be stable. With additional core electron heating, FIR scattering measurements near the axis show the presence of high k fluctuations (12 cm-l), rotating in the electron diamagnetic drift direction. This turbulence could impact electron transport and possibly also ion transport. Thermal diffusivities for electrons, and to a lesser degree ions, increase. The ETG mode can exist at this wavenumber, but it is computed to be robustly stable near the axis.
Date: November 24, 1998
Creator: Stallard, B. W.
Partner: UNT Libraries Government Documents Department

Initial single-shell tank retrieval system tank selection

Description: The Hanford Federal Facility Agreement and Consent Order (also known as the Tri-Party Agreement), established several milestones associated with the Initial Single-Shell Tank Retrieval System (ISSTRS). It also established that the scope of ISSTRS is the retrieval of a complete tank farm or an equivalent number of tanks. This study selected the single- shell tanks to be included in the ISSTRS work scope. This study determined that the ISSTRS work scope should consist of four tanks located in the A, AX, and C, tank farms. One of the tanks (Tank 241-AX-103) will be a salt cake retrieval demonstration tank. The other three (Tanks 241 -A-1 02, 241 -C-1 03, and 241-C-105) are 100-series tanks containing high interim storage risk, high long-term hazard waste and are assumed not to be leaking.
Date: October 24, 1996
Creator: Grenard, C.E.
Partner: UNT Libraries Government Documents Department

1995 Annual report on waste generation and waste mainization progress as required by DOE order 5400.1, Hanford site

Description: While waste generation numbers are important, the true measure of success is waste minimized. Many Waste Minimization/Pollution Prevention (WMin/P2) successes at the Hanford Site occur every day without formal recognition as pollution prevention, as they have become part of a culture of best management practices. As an example, the success of the excess and reuse program, both informal and formal, documents the Wmin/P2 culture that exists in the pollution prevention representatives and employees at the facilities.
Date: September 24, 1996
Creator: Betsch, M.D.
Partner: UNT Libraries Government Documents Department

Farinon microwave end of life cycle

Description: This engineering report evaluates alternatives for the replacement of the Farinon microwave radio system. The system is beyond its expected life cycle and has decreasing maintainability. Principal applications supported by the Farinon system are two electrical utility monitor and control systems, the Integrated Transfer Trip System (ITTS), and the Supervisory Control and Data Acquisition (SCADA) system.
Date: June 24, 1996
Creator: Poe, R.C.
Partner: UNT Libraries Government Documents Department

Bioremediation of mixed microbial mats: System development of mixed contaminants for application at the Savannah River Site. Annual technical progress report, October 1, 1995--September 30, 1996

Description: The fundamental objective of this project is to develop and field test the mixed microbial mat bioremediation system for decontamination of target sites at SRS. Although microbial mats have performed well in several pilot projects in the past, atypical problems and site characteristics at SRS demand special field designs. In the interest of designing a pilot and locating it at an appropriate site, the project investigators have worked closely with the technical staff at the SREL. We have concluded that the diverse characteristics of contaminations at SRS may dictate testing several pilot designs during the course of this project.
Date: September 24, 1996
Creator: Bender, J. & Phillips, P.
Partner: UNT Libraries Government Documents Department

Review of Subcritical Source-Driven Noise Analysis Measurements

Description: Subcritical source-driven noise measurements are simultaneous Rossi-{alpha} and randomly pulsed neutron measurements that provide measured quantities that can be related to the subcritical neutron multiplication factor. In fact, subcritical source-driven noise measurements should be performed in lieu of Rossi-{alpha} measurements because of the additional information that is obtained from noise measurements such as the spectral ratio and the coherence functions. The basic understanding of source-driven noise analysis measurements can be developed from a point reactor kinetics model to demonstrate how the measured quantities relate to the subcritical neutron multiplication factor. More elaborate models can also be developed using a generalized stochastic model. These measurements can be simulated using Monte Carlo codes to determine the subcritical neutron multiplication factor or to determine the sensitivity of calculations to nuclear cross section data. The interpretation of the measurement using a Monte Carlo method is based on a perturbation model for the relationship between the spectral ratio and the subcritical neutron multiplication factor. The subcritical source-driven noise measurement has advantages over other subcritical measurement methods in that reference measurements at delayed critical are not required for interpreting the measurements. Therefore, benchmark or in-situ subcritical measurements can be performed outside a critical experiment facility. Furthermore, a certain ratio of frequency spectra has been shown to be independent of detection efficiency thereby making the measurement more robust and unaffected by drifts or changes in instrumentation during the measurement. Criteria have been defined for application of this measurement method for benchmarks and in-situ subcritical measurements. An extension of the source-driven subcritical noise measurement has also been discussed that eliminates the few technical challenges for in-situ applications.
Date: November 24, 1999
Creator: Valentine, T.E.
Partner: UNT Libraries Government Documents Department