Author: Robert Edward KelleyPublisher:
ISBN:
Category :
Languages : en
Pages : 132
Book Description
Integral Measurements of Thermal Neutron Spectra
Author: Robert Edward KelleyPublisher:
ISBN:
Category :
Languages : en
Pages : 132
Book Description
Measurements of Thermal Neutron Cross Section and Resonance Integral for the 237Np(n,?)238Np Reaction
Author: K. KobayashiPublisher:
ISBN:
Category : 1/E spectrum field
Languages : en
Pages : 9
Book Description
Making use of a standard neutron spectrum field with a pure Maxwellian distribution at the heavy water thermal neutron facility of the Kyoto University Reactor (KUR), the thermal neutron cross section for the 237Np(n,?)238Np reaction was measured by the activation method, using a high purity Ge detector. The result is 158±3 b, which is obtained relative to the reference value of 98.65±0.09 b for the 197Au(n,?)198Au reaction. The present value is lower by about 13% than that of the ENDF/B-VI data. The data given by Mughabghab and obtained from JENDL-3 are larger by 11 to 14% than the present measurement.
Status of the Dosimetry for the Radiation Effects Research Foundation (DS86)
Author: National Research CouncilPublisher: National Academies Press
ISBN: 0309075599
Category : Science
Languages : en
Pages : 211
Book Description
The Committee on Dosimetry for the Radiation Effects Research Foundation (RERF) was set up more than a decade ago at the request of the U.S. Department of Energy. It was charged with monitoring work and experimental results related to the Dosimetry System 1986 (DS86) used by RERF to reconstruct the radiation doses to the survivors in Hiroshima and Nagasaki. At the time it was established, DS86 was believed to be the best available dosimetric system for RERF, but questions have persisted about some features, especially the estimates of neutrons resulting from the Hiroshima bomb. This book describes the current situation, the gamma-ray dosimetry, and such dosimetry issues as thermal-neutron discrepancies between measurement and calculation at various distances in Hiroshima and Nagasaki. It recommends approaches to bring those issues to closure and sets the stage for the recently convened U.S. and Japan Working Groups that will develop a new dosimetry for RERF. The book outlines the changes relating to DS86 in the past 15 years, such as improved numbers that go into, and are part of, more sophisticated calculations for determining the radiations from bombs that reach certain distances in air, and encourages incorporation of the changes into a revised dosimetry system.
The Measurement of Thermal Neutron Spectra in Heterogeneous Lattices by Foil Activation
Author: Gregg Woodford DixonPublisher:
ISBN:
Category : Lattices
Languages : en
Pages : 158
Book Description
Integral Neutron Thermalization, Annual Summary Report, October 1 ... - September 30 ...
Author: Comparison Between Measured and Calculated Stationary Thermal Neutron Spectra in Heterogeneous Systems
Author: Leopold Maria CaspersPublisher:
ISBN:
Category : Heavy water reactors
Languages : en
Pages : 114
Book Description
Measurements of the Spatial and Energy Distribution of Thermal Neutrons in Uranium, Heavy Water Lattices
Author: Paul S. BrownPublisher:
ISBN:
Category : Heavy water reactors
Languages : en
Pages : 420
Book Description
Intracell activity distributions were measured in three natural uranium, heavy water lattices of 1. 010 inch diameter, aluminum clad rods on triangular spacings of 4. 5 inches, 5. 0 inches, and 5. 75 inches, respectively, and in a uranium, heavy water lattice of 0. 25 inch diameter, 1. 03% U 2235, aluminum-clad rods on a triangular spacing of 1. 25 inches. The distributions were measured with bare and cadmium-covered foils of gold, lutetium, and europium. The gold was used as a 1/v absorber to measure the thermal neutron density distribution. Because the activation cross sections of lutetium and europium depart considerably from 1/v behavior, their activation depends strongly on the thermal neutron energy spectrum. Hence, they were used to make integral measurements of the change in the neutron energy spectrum with position in the lattice cell. A method was developed for treating the partial absorption, by cadmium covers, of neutrons at the 0. 46 ev europium resonance, and it was found possible to correct the europium activations to energy cutoffs just above and just below the resonance. The measured activity distributions were compared with those computed with the THERMOS code. In the natural uranium lattices, THERMOS gave excellent agreement with the measured gold activity distributions and very good agreement with the lutetium and europium distributions, indicating that THERMOS gives a very good estimate of the spatial and energy distribution of thermal neutrons in these lattices. In the enriched lattice, THERMOS gave a large overestimate of the activity dip in the fuel for all three detectors. The discrepancy was attributed to a breakdown in the Wigner-Seitz cylindrical cell approximation at small cell radii. However, the measured ratios of lutetium and europium activity to gold activity were in good agreement with the THERMOS values, indicating that THERMOS still gave a good estimate of the degree of spectral hardening. Neutron temperature calculations were made from the data by using Westcott effective cross sections. The temperature changes so calculated agreed well with those predicted by THERMOS. Disadvantage factors calculated by the Amouyal-Benoist-Horowitz (ABH) method were in excellent agreement with the measured values in the natural uranium lattices. The agreement was not as good in the enriched lattice because of an expected breakdown in the ABH method at small cell radii. Values of the thermal utilization obtained from experiment, from THERMOS, and with the ABH method were in excellent agreement for all the lattices studied. Radial and axial buckling measurements made with lutetium were in excellent agreement with similar measurements made with gold, indicating that the thermal neutron spectrum was uniform throughout the lattice tank. Measurements of intracell gold activity distributions made in off-center cells differed only slightly from those made in the central cell of the lattice, indicating that the radial flux distribution was almost completely separable into a macroscopic Jo and a microscopic cell distribution.
Proceedings of the Brookhaven Conference on Neutron Thermalization, April 30-May 2, 1962: Neutron spectra in lattices and infinite media
Author: Brookhaven National LaboratoryPublisher:
ISBN:
Category : Neutrons
Languages : en
Pages : 598
Book Description
A Review of the Methods for Computing Thermal Neutron Spectra
Author: Henry C. HoneckPublisher:
ISBN:
Category : Neutrons
Languages : en
Pages : 76
Book Description
Author: D.B. Gayther