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Measurement of neutron spectra in varied environments by the foil-activation method with arbitrary trials

Description: Neutron spectra have been measured by the foil-activation method in 13 different environments in and around the Sandia Pulsed Reactor, the White Sands Missile Range Fast Burst Reactor, and the Sandia Annular Core Research Reactor. The spectra were obtained by using the SANDII code in a manner that was not dependent on the initial trial. This altered technique is better suited for the determination of spectra in environments that are difficult to predict by calculation, and it tends to reveal features that may be biased out by the use of standard trial-dependent methods. For some of the configurations, studies have also been made of how well the solution is determined in each energy region. The experimental methods and the techniques used in the analyses are thoroughly explained. 34 refs., 51 figs., 40 tabs.
Date: December 1, 1987
Creator: Kelly, J.G. & Vehar, D.W.
Partner: UNT Libraries Government Documents Department

Transimssion and compression of an intense relativistic electron beam produced by a converging annular diode with return current feedback through the cathode. Part II. The experiments

Description: The complete results of the experiments with the converging annular diode within return current feedback through the cathode (Triax) are reported herein. The diode was designed to focus a relativistic high-current electron beam to a small focus. It did confirm the Triaxial theory detailed in Part I, and it did achieve a factor of 10 areal compression with 50% efficiency (which was below expectations). There were two principal reasons for this shortfall. First, the rapid diode plasma motion of 10 cm/..mu..sec that was discovered necessitated the use of larger A-K gaps than expected and led to thicker beam sheets than are needed for good focusing. Second, the intrinsic angular spread of the electrons, even from the best cathode surfaces, introduced excessive angular momentum into the beam so that only a minor portion of the electrons could reach the axis. However, the yield of useful information about diode physics in general and about the influence of prepulse, the role of diode plasmas, the motion of energetic beams within conducting boundaries, diode emission properties, and diode diagnostic techniques in particle has had a significant and useful impact on the electron beam program at Sandia.
Date: February 1, 1976
Creator: Kelly, J. G. & Schuch, R. L.
Partner: UNT Libraries Government Documents Department

Coded aperture imaging of reactor illuminated LMFBR fuel pins

Description: As a part of Sandia Laboratories program to study simulated core disruptive accidents in reactor safety research, a fuel motion detection system based on coded aperture imaging is being developed. Until the experiments reported here were conducted it was not known whether either of two important questions could be properly answered. First, could an actual fuel pin illuminated by a reactor be imaged with a coded aperture and an active detector system with acceptable frame rates and spatial resolution. Second, could collimator and shield structures be fabricated for the Annular Core Pulsed Reactor (ACPR), for which the system is being built, that would provide acceptable signal to background ratios. Both of these questions can now be answered in the affirmative because of the favorable experiments recently conducted at the Sandia Pulsed Reactor (SPR II) and at the ACPR.
Date: January 1, 1977
Creator: Kelly, J. G. & Stalker, K. T.
Partner: UNT Libraries Government Documents Department

An ``exact`` treatment of self-shielding and covers in neutron spectra determinations

Description: Most neutron spectrum determination methodologies ignore self-shielding effects in dosimetry foils and treat covers with an exponential attenuation model. This work provides a quantitative analysis of the approximations in this approach. It also provides a methodology for improving the fidelity of the treatment of the dosimetry sensor response to a level consistent with the user`s spectrum characterization approach. A library of correction functions for the energy-dependent sensor response has been compiled that addresses dosimetry foils/configurations in use at the Sandia National Laboratories Radiation Metrology Laboratory.
Date: June 1, 1995
Creator: Griffin, P.J. & Kelly, J.G.
Partner: UNT Libraries Government Documents Department

Status of neutron dosimetry cross sections

Description: Several new cross section libraries, such as ENDF/B-VI(release 2), IRDF-90,JEF-2.2, and JENDL-3 Dosimetry, have recently been made available to the dosimetry community. the Sandia National Laboratories (SNL) Radiation Metrology Laboratory (RML) has worked with these libraries since pre-release versions were available. this paper summarizes the results of the intercomparison and testing of dosimetry cross sections. As a result of this analysis, a compendium of the best dosimetry cross sections was assembled from the available libraries for use within the SNL RML. this library, referred to as the SNLRML Library, contains 66 general dosimetry sensors and 3 special dosimeters unique to the RML sensor inventory. The SNLRML cross sections have been put into a format compatible with commonly used spectrum determination codes.
Date: December 31, 1992
Creator: Griffin, P. J. & Kelly, J. G.
Partner: UNT Libraries Government Documents Department

Characterization of the SPR II generated radiation environments next to and within a guidance system

Description: The neutron fluences and spectra and the gamma ray doses inside and in the vicinity of a guidance system exposed to the Sandia Pulsed Reactor II (SPR II) in four configurations have been determined. This project required customization of the environment and the application of new techniques to determine the spectra within the system. The required radiation environment was achieved, and the experimental results clearly demonstrated that the radiation environment inside the system was very different from that seen outside. This example demonstrates very clearly that experimenters must consider the effect the test apparatus may have on the environment inside the system.
Date: February 1994
Creator: Kelly, J. G. & Griffin, P. J.
Partner: UNT Libraries Government Documents Department

Factors affecting use of fission foils as dosimetry sensors

Description: Fission foils are commonly used as dosimetry sensors. They play a very important role in neutron spectrum determinations. This paper provides a combination of experimental measurements and calculations to quantify the importance and synergy of several factors that affect the fission response of a dosimeter. Only when these effects are properly treated can fission dosimeters be used with sufficient fidelity.
Date: December 31, 1996
Creator: Griffin, P.J.; Vehar, D.W.; Kelly, J.G. & Holm, C.V.
Partner: UNT Libraries Government Documents Department

Benchmarking the Sandia Pulsed Reactor III cavity neutron spectrum for electronic parts calibration and testing

Description: The SPR III bare cavity spectrum and integral parameters have been determined with 24 measured spectrum sensor responses and an independent, detailed, MCNP transport calculation. This environment qualifies as a benchmark field for electronic parts testing.
Date: August 1, 1993
Creator: Kelly, J. G.; Griffin, P. J. & Fan, W. C.
Partner: UNT Libraries Government Documents Department

Neutron dosimetry with the {sup 58}Ni(n,p){sup 58}Co reaction at short-decay times

Description: The {sup 58}Ni(n,p){sup 58}Co reaction is a very attractive choice for use as shown a neutron fluence monitor foil in reactor irradiations. The most important drawback to this reaction is the interference from the 9.15-h half-life {sup 58m}Co metastable state. A methodology is presented in this paper to allow the {sup 58g}Co ground-state activity to be read at short decay times and to be converted into the total {sup 58t}Co activity with no significant increase in the measurement uncertainty. This methodology involves modeling the {sup 58m}Co/{sup 58t}Co population ratio. Both theoretical and experimental estimates of the energy dependence of this ratio are presented. A method is presented to accurately measure this ratio. An empirical model of the energy dependence of this ratio is presented to allow simple estimates of the ratio to be made prior to a measurement.
Date: December 31, 1992
Creator: Griffin, P. J.; Holm, C. V.; Vehar, D. W. & Kelly, J. G.
Partner: UNT Libraries Government Documents Department

SNL RML recommended dosimetry cross section compendium

Description: A compendium of dosimetry cross sections is presented for use in the characterization of fission reactor spectrum and fluence. The contents of this cross section library are based upon the ENDF/B-VI and IRDF-90 cross section libraries and are recommended as a replacement for the DOSCROS84 multigroup library that is widely used by the dosimetry community. Documentation is provided on the rationale for the choice of the cross sections selected for inclusion in this library and on the uncertainty and variation in cross sections presented by state-of-the-art evaluations.
Date: November 1, 1993
Creator: Griffin, P. J.; Kelly, J. G.; Luera, T. F. & VanDenburg, J.
Partner: UNT Libraries Government Documents Department

Updated neutron spectrum characterization of SNL baseline reactor environments. Volume 1, Characterization

Description: The neutron spectrum characteristics of the primary reactor environments are defined for use by facility customers and to provide an audit trail in support of current quality assurance initiatives. The neutron and gamma environments in the four primary customer environments at SPR-III and ACRR facilities are characterized in detail. Enough detail is provided on other frequently-used environments to support the definition of the 3-MeV and 1-MeV(Si) fluence provided on the Radiation Metrology Laboratory dosimetry reports.
Date: April 1, 1994
Creator: Griffin, P. J.; Kelly, J. G. & Vehar, D. W.
Partner: UNT Libraries Government Documents Department

Updated neutron spectrum characterization of SNL baseline reactor environments. Volume 2, Analysis computer listings

Description: This document provides SAND-II and MANIPULATE output listings from calculations used to derive the new spectrum-averaged integral parameters that were reported in volume 1. When used in conjunction with volume 1, this document provides an audit trail for the neutron radiation field characterization and supports current quality assurance initiatives. This document provides detailed information on the neutron spectrum characteristics of the primary Sandia National Laboratories` (SNL) reactor environments. The information in this volume is not intended for the casual user of the SNL reactor facilities. This detailed characterization of the neutron and gamma environments at the Sandia Pulsed Reactor (SPR) and the Annular Core Research Reactor (ACRR) is provided to aid the users who wish to convert the information given in the Radiation Metrology Laboratory (RML) dosimetry reports into other (non-silicon) measures of neutron damage. The spectra provided in these appendices can be used as a source term for Monte Carlo radiation transport calculations to study the impact of experimenter`s test package on the neutron environment.
Date: April 1, 1994
Creator: Griffin, P. J.; Kelly, J. G. & Vehar, D. W.
Partner: UNT Libraries Government Documents Department

User`s manual for SNL-SAND-II code

Description: Sandia National Laboratories, in the process of characterizing the neutron environments at its reactor facilities, has developed an enhanced version of W. McElroy`s original SAND-II code. The enhanced input, output, and plotting interfaces make the code much easier to use. The basic physics and operation of the code remain unchanged. Important code enhancements include the interfaces to the latest ENDF/B-VI and IRDF-90 dosimetry-quality cross sections and the ability to use silicon displacement-sensitive devices as dosimetry sensors.
Date: April 1, 1994
Creator: Griffin, P. J.; Kelly, J. G. & VanDenburg, J. W.
Partner: UNT Libraries Government Documents Department

Fast shutter for low background radiation environments at SPR III

Description: A fast shutter system has been developed and used to isolate experiments from the radiation emitted after the main pulse of the Sandia Pulse Reactor, SPR 3. In about 15 ms the system moves a massive 20 kg shield in front of the beam port aperture in the facility shield wall. A second gravity-driven shutter is dropped into place in about 200 ms. The total attenuation achieved in the beam intensity is about a factor of one hundred. The shutter assembly was used, along with a sensitive detection system, to observe the gamma ray flux emitted by various materials activated by the neutron beam at levels nine orders of magnitude smaller than the gamma flux level at the target during the reactor pulse.
Date: August 1, 1994
Creator: Kelly, J. G.; Sites, K. & Scott, W.
Partner: UNT Libraries Government Documents Department

Characterization of reactor neutron environments at Sandia National Laboratories

Description: To assure quality in the testing of electronic parts in neutron radiation environments, Sandia National Laboratories (SNL) has incorporated modern techniques and procedures, developed in the last two decades by the radiation effects community, into all of its experimental programs. Attention to the application of all of these methodologies, experiment designs, nuclear data, procedures and controls to the SNL radiation services has led to the much more accurate and reliable environment characterizations required to correlate the effects observed with the radiation delivered.
Date: August 1, 1994
Creator: Kelly, J. G.; Luera, T. F.; Griffin, P. J. & Vehar, D. W.
Partner: UNT Libraries Government Documents Department

Theory and application of the coded aperture fuel motion detection system

Description: A fuel motion detection system based on coded aperture imaging has been developed for the Annular Core Research Reactor. Its configuration evolved after investigations were carried out to determine the required system capabilities. The reactor environment, developments in the theory of coded apertures for nuclear radiations and compatibility with prototypical geometries were considered. The system was fabricated and inserted into the ACRR where it has recorded the fuel motion from a single pin subjected to loss of flow accident conditions. In addition, computer simulations have shown that in the reactor environment and for fast data acquisition, coded imaging, particularly with uniformly redundant arrays, offers significant advantages over pinhole camera geometries. The extension of this technique toward imaging of 37-pin bundles and imaging with fast neutrons is also being investigated.
Date: January 1, 1979
Creator: Kelly, J.G.; Stalker, K.T.; McArthur, D.A.; Chu, K.W. & Powell, J.E.
Partner: UNT Libraries Government Documents Department

Interlaboratory verification of neutron spectra used for the testing of electronic parts

Description: A methodology has been developed for verifying that a neutron energy spectrum measured for an environment correctly predicts the bulk displacement damage that would be observed in a silicon electronic device. The technique makes use of a package of silicon bipolar transistors (2N2222A), monitor activation foils (such as sulfur pellets), and thermoluminescence detectors (TLDs) that is placed in the test environment. The TLDs and monitors are then used to correct for the gamma-induced damage and to scale the reactor power in the test irradiation to that predicted by the neutron spectrum which is being verified. The damage predicted from the spectrum and the measured damage are then compared. In cases where the sensor set does not have sufficient sensitivity coverage to satisfactorily define the spectrum, the transistors can be used as spectrum sensors to provide sensitivity in the crucial energy region between 0.1 and 2.0 MeV. This results in the loss of the independent verification, but leads in a much higher fidelity spectrum. The technique greatly facilitates inter- and intralaboratory comparisons of effects testing and spectrum determinations.
Date: December 31, 1992
Creator: Kelly, J. G.; Griffin, P. J.; Raupach, D. C.; Daubenspect, T. H.; Bennion, J. S. & Newell, D. L.
Partner: UNT Libraries Government Documents Department

An examination of the 1-MeV equivalent silicon damage methodology

Description: The assumptions, approximations, and uncertainty in the 1-MeV equivalent silicon damage methodology are reviewed. A new silicon displacement kerma function, based on ENDF/B-VI cross sections, is presented and its shape is experimentally confirmed. The issue of an associated 1-MeV equivalent reference kerma value is discussed. 19 refs., 4 figs.
Date: January 1, 1990
Creator: Griffin, P.J.; Kelly, J.G.; Luera, T.F. (Sandia National Labs., Albuquerque, NM (USA)) & Lazo, M.S. (New Mexico Univ., Albuquerque, NM (USA). Dept. of Chemical and Nuclear Engineering)
Partner: UNT Libraries Government Documents Department