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Processing needs and constraints: neutron data processing

Description: New applications for processed data and increased accuracy requirements have generated needs for change in the Evaluated Nuclear Data Files (ENDF). Some constraints must be removed to allow this growth to take place, but other strong constraints must remain to protect existing users.
Date: January 1, 1980
Creator: MacFarlane, R.E.
Partner: UNT Libraries Government Documents Department

Integrated system for production of neutronics and photonics calculational constants. Neutron-induced interactions: bibliography of experimental data

Description: The bibliographic citations in the Experimental Cross Section Information Library (ECSIL) as of July 4, 1976 are tabulated. The tabulation has three arrangements: alphabetically by author, alphabetically by publication, and numerically by reference number.
Date: July 4, 1976
Creator: MacGregor, M. H.; Cullen, D. E.; Howerton, R. J. & Perkins, S. T.
Partner: UNT Libraries Government Documents Department

Integrated system for production of neutronics and photonics calculational constants. Supplemental neutron-induced interactions (Z less than or equal to 35): graphical, experimental data

Description: This report (Vol. 8) presents graphs of supplemental neutron-induced cross sections in the Experimental Cross Section Information Library (ECSIL) as of July 4, 1976. It consists of interactions where more than one data set is needed to show cross-section behavior. In contrast, Vol. 7 of this UCRL-50400 series consists primarily of interactions where a single data set contains enough points to show cross-section behavior. In Vol. 7 can be found the total, elastic, capture, and fission cross sections (along with the parameters anti ..nu.., ..cap alpha.., and eta). Volume 8 contains all other reactions. Data are plotted with associated cross-section error bars (when given) and compared with the Evaluated Nuclear Data Library (ENDL) as of July 4, 1976. The plots are arranged in ascending order of atomic number (Z) and atomic weight (A). Part A contains the plots for Z = 1 to 35; Part B contains the plots for Z greater than 35.
Date: July 4, 1976
Creator: Cullen, D. E.; Howerton, R. J.; MacGregor, M. H. & Perkins, S. T.
Partner: UNT Libraries Government Documents Department

Integrated system for production of neutronics and photonics calculational constants. Volume 15, Part C. The LLL Evaluated Nuclear Data Library (ENDL): translation of ENDL neutron-induced interaction data into the ENDF/B format

Description: The LLL evaluated nuclear data library (ENDL) has been translated into the evaluated neutron data file/version B (ENDF/B) format. This translation is for the convenience of those who wish to use ENDL data but who are more familiar with ENDF/B formats and procedures. Only that portion of ENDL dealing with neutron-induced interactions (including photon production from neutron-induced reactions) has been translated.
Date: April 1, 1976
Creator: Howerton, R. J.
Partner: UNT Libraries Government Documents Department

Integrated system for production of neutronics and photonics calculational constants. Neutron-induced interactions: index of experimental data

Description: Indexes to the neutron-induced interaction data in the Experimental Cross Section Information Library (ECSIL) as of July 4, 1976 are tabulated. The tabulation has two arrangements: isotope (ZA) order and reaction-number order.
Date: July 4, 1976
Creator: MacGregor, M. H.; Cullen, D. E.; Howerton, R. J. & Perkins, S. T.
Partner: UNT Libraries Government Documents Department

Nuclear physics in the 10 to 300 MeV energy range using a pulsed white neutron source

Description: A new pulsed white neutron source is under construction at the Los Alamos WNR facility. The neutrons are produced by LAMPF proton micropulses striking thick targets of various materials. Beam parameters include energy of 800 MeV, pulse rate of approximately 50,000 Hz, 0.4 nsec pulse width, average current as high as 6..mu..a, and a useful neutron energy range from 3 to 300 MeV. The facility will receive beam approximately 80% of the time LAMPF is operational; it increased by a factor of 1000 the experimental capability over the present system at the WNR when beam intensity, angular distribution, and availability are taken into account. In addition to established white source techniques, the facility is also highly competitive with monoenergetic sources for a wide class of experiments such as neutron capture ..gamma.. ray spectroscopy and neutron-induced charged particle reactions. The facility should be operational in about nine months. Arrangements are underway to make the facility readily accessible to visiting experimenters.
Date: January 1, 1984
Creator: Bowman, C.D.; Wender, S.A. & Auchampaugh, G.F.
Partner: UNT Libraries Government Documents Department

Neutron Physics Division progress report for period ending February 28, 1977

Description: Summaries are given of research progress in the following areas: (1) measurements of cross sections and related quantities, (2) cross section evaluations and theory, (3) cross section processing, testing, and sensitivity analysis, (4) integral experiments and their analyses, (5) development of methods for shield and reactor analyses, (6) analyses for specific systems or applications, and (7) information analysis and distribution. (SDF)
Date: May 1, 1977
Creator: Maienschein, F. C.
Partner: UNT Libraries Government Documents Department

Analysis of the sensitivity of spectrum-average cross sections to individual characteristics of differential excitation functions

Description: A simple procedure for analyzing the sensitivity of computed spectrum-average cross sections to detailed properties of excitation functions for threshold nuclear reactions commonly used in reactor dosimetry is described. This procedure is shown to be useful in identifying specific needs for improved differential data and as a tool to be employed in performing evaluations. Several examples are presented to illustrate the subject matter.
Date: March 1, 1977
Creator: Smith, D. L.
Partner: UNT Libraries Government Documents Department

Evaluating fission neutron-multiplicity data

Description: The present work had its origins in the practical need to obtain P[sub [nu]] for the purpose of calculating the theoretical response of instrumentation that used a correlation technique to assay spontaneously fissioning nuclides. The assay results are proportional to the factorial moments calculated with the P[sub [nu]] distribution. Obtaining experimentally derived sets of P[sub [nu]] from many sources reported over several decades led immediately to the problem of evaluating the data: Aside from the trivial problem of sometimes not being properly normalized, the first moments ([nu]) = ([nu]) = [Sigma][nu]P[sub [nu]] were typically not in accord with the best recent evaluations, or the calibration of detector efficiency was based on obsolete values for ([nu]) for supposedly well-characterized standard'' nuclides such as [sup 252]Cf. The problem of evaluating P[sub [nu]] is unusual in that, compared to the usual situation where the quantities being evaluated are single numbers, the P[sub [nu]] are sets of numbers, that moreover, are constrained so that [Sigma]P[sub [nu]][triple bond] 1 and [Sigma][nu] P[sub [nu]] = ([nu]), where ([nu]) is usually determined more accurately from a separate experiment than it can be calculated from the experimentally derived P[sub [nu]] distribution.
Date: January 1, 1992
Creator: Zucker, M. S. & Holden, N. E.
Partner: UNT Libraries Government Documents Department

Nuclear data requirements for fusion reactor nucleonics

Description: Nuclear data requirements for fusion reactor nucleonics are reviewed and the present status of data are assessed. The discussion is divided into broad categories dealing with data for Fusion Materials Irradiation Test Facility (FMIT), D-T Fusion Reactors, Alternate Fuel Cycles and the Evaluated Data Files that are available or would be available in the near future.
Date: January 1, 1980
Creator: Bhat, M.R. & Abdou, M.A.
Partner: UNT Libraries Government Documents Department

Critical radius and critical number of gas atoms for cavities containing a Van der Waals gas

Description: The effect of gas on void nucleation and growth is particularly important for structural materials in fusion reactors because of the high production of helium by neutron-induced transmutation reactions. Gas reduces the critical radius for bias driven growth and there is a critical number of gas atoms, n/sub g/*, at which the critical radius is reduced essentially to zero. The significance of this is that the time interval to the accumulation of n/sub g/* gas atoms may determine the time to the onset of bias driven swelling where n/sub g/* is large. In previous papers these critical quantities were given for an ideal gas. Recently, we presented the results for a Van der Waals gas. Here the derivation of these relations is presented and further results of calculations are given. At low temperatures (high pressures) the results depart from those of the ideal gas, with the critical number affected more strongly than the critical radius. Comparisons are made with earlier calculations.
Date: January 1, 1983
Creator: Coghlan, W.A. & Mansur, L.K.
Partner: UNT Libraries Government Documents Department

Nuclear structure studies at intermediate energies. Annual progress report, November 1979-October 1980. [Univ. of Minnesota, 11/79-10/80]

Description: Research during the period November 1979 through October 1980 is reported. Completed work will be published in the usual places. Three sections containing significant amounts of information are abstracted separately. (RWR)
Date: January 1, 1980
Creator: Hintz, N. M.; Franey, M. A.; Gazzaly, M.; Cook, D.; Owen, K. & Overacker, L.
Partner: UNT Libraries Government Documents Department

Consistency of differential and integral thermonuclear neutronics data

Description: To increase the accuracy of the neutronics analysis of nuclear reactors, physicists and engineers have employed a variety of techniques, including the adjustment of multigroup differential data to improve consistency with integral data. Of the various adjustment strategies, a generalized least-squares procedure which adjusts the combined differential and integral data can significantly improve the accuracy of neutronics calculations compared to calculations employing only differential data. This investigation analyzes 14 MeV neutron-driven integral experiments, using a more extensively developed methodology and a newly developed computer code, to extend the domain of adjustment from the energy range of fission reactors to the energy range of fusion reactors.
Date: January 1, 1978
Creator: Reupke, W.A.
Partner: UNT Libraries Government Documents Department

Use of R-matrix methods for light element evaluations

Description: Some general aspects of parameterizing nuclear reaction data with a unitary, multichannel theory are discussed. The special case of R-matrix theory are discussed. The special case of R-matrix theory is considered, where the explicit separation of long- and short-range forces and the natural occurrence of energy pole terms afford a number of advantages in describing data for light-element reactions. Examples are given for both neutron- and charged-particle-induced reactions which illustrate multichannel R-matrix techniques, including the use of charge symmetry to relate data for mirror systems. The limitations of conventional R-matrix methods are discussed briefly.
Date: January 1, 1980
Creator: Hale, G.M.
Partner: UNT Libraries Government Documents Department

Nuclear data and related services

Description: National Nuclear Data Center (NNDC) maintains a number of data bases containing bibliographic information and evaluated as well as experimental nuclear properties. An evaluated computer file maintained by the NNDC, called the Evaluated Nuclear Structure Data File (ENSDF), contains nuclear structure information for all known nuclides. The ENSDF is the source for the journal ''Nuclear Data Sheets'' which is produced and edited by NNDC. The Evaluated Nuclear Data File (ENDF), on the other hand is designed for storage and retrieval of such evaluated nuclear data as are used in neutronic, photonic, and decay heat calculations in a large variety of applications. Some of the publications from these data bases are the Nuclear Wallet Cards, Radioactivity Handbook, and books on neutron cross sections and resonance parameters. In addition, the NNDC maintains three bibliographic files: NSR - for nuclear structure and decay data related references, CINDA - a bibliographic file for neutron induced reactions, and CPBIB - for charged particle reactions. Selected retrievals from evaluated data and bibliographic files are possible on-line or on request from NNDC. 6 refs., 1 fig.
Date: January 1, 1985
Creator: Tuli, J.K.
Partner: UNT Libraries Government Documents Department

Energy-averaged neutron cross sections of fast-reactor structural materials

Description: The status of energy-averaged cross sections of fast-reactor structural materials is outlined with emphasis on U.S. data programs in the neutron-energy range 1-10 MeV. Areas of outstanding accomplishment and significant uncertainty are noted with recommendations for future efforts. Attention is primarily given to the main constituents of stainless steel (e.g., Fe, Ni, and Cr) and, secondarily, to alternate structural materials (e.g., V, Ti, Nb, Mo, Zr). Generally, the mass regions of interest are A approximately 50 to 60 and A approximately 90 to 100. Neutron total and elastic-scattering cross sections are discussed with the implication on the non-elastic-cross sections. Cross sections governing discrete-inelastic-neutron-energy transfers are examined in detail. Cross sections for the reactions (n;p), (n;n',p), (n;..cap alpha..), (n;n',..cap alpha..) and (n;2n') are reviewed in the context of fast-reactor performance and/or diagnostics. The primary orientation of the discussion is experimental with some additional attention to the applications of theory, the problems of evaluation and the data sensitivity of representative fast-reactor systems.
Date: February 1, 1978
Creator: Smith, A.; McKnight, R. & Smith, D.
Partner: UNT Libraries Government Documents Department

Analysis of the /sup 235/U neutron cross sections in the resolved resonance range

Description: Using recent high-resolution measurements of the neutron transmission of /sup 235/U and the spin-separated fission cross-section data of Moore et al., a multilevel analysis of the /sup 235/U neutron cross sections was performed up to 300 eV. The Dyson Metha ..delta../sub 3/ statistics were used to help locate small levels above 100 eV where resonances are not clearly resolved even in the best resolution measurements available. The statistical properties of the resonance parameters are discussed. 13 refs., 8 figs., 1 tab.
Date: January 1, 1989
Creator: Leal, L.C.; de Saussure, G. & Perez, R.B.
Partner: UNT Libraries Government Documents Department

Fission cross section ratios for sup 233,234,236 U relative to sup 235 U from 0. 5 to 400 MeV

Description: Neutron-induced fission cross section ratios from 0.5 to 400 MeV for samples of {sup 233, 234, 236}U relative to {sup 235}U have been measured at the WNR neutron Source at Los Alamos. The fission reaction rate was determined using a fast parallel plate ionization chamber at a 20-m flight path. Cross sections over most the energy range were also extracted using the neutron fluence determined with three different proton telescope arrangements. Those data provided the shape of the {sup 235}U(n,f) cross section relative to the hydrogen scattering cross section. That shape was then normalized to the very accurately known value for {sup 235}U(n,f) at 14.1 MeV to allow us to obtain cross section section values from the ratio data and our values for {sup 235}U(n,f). 6 refs., 1 fig.
Date: January 1, 1991
Creator: Lisowski, P.W.; Gavron, A.; Parker, W.E.; Balestrini, S.J. (Los Alamos National Lab., NM (USA)); Carlson, A.D.; Wasson, O.A. (National Inst. of Standards and Technology, Gaithersburg, MD (USA)) et al.
Partner: UNT Libraries Government Documents Department

Perspective on occupational radiation exposures at a hypothetical fusion power station

Description: If current technology were used, several major sources of potential occupational radiation exposure at fusion power stations would be quite similar to those at current light water reactor power stations. Based upon this similarity, crude estimates of doses received from various maintenance operations at fusion power reactors are made. The dose estimates reinforce the need for concurrent development of sophisticated remote maintenance devices and low-activation materials for fusion reactors. It is concluded that minimization of occupational doses can be best achieved by developing an overall maintenance strategy that combines the best features of remote techniques and low activation materials as opposed to developing one or the other exclusively.
Date: January 1, 1983
Creator: Easterly, C.E. & Cannon, J.B.
Partner: UNT Libraries Government Documents Department