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

Abstract

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 SAND11 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. C. Holm, who counted the foils and reliably reduced the data to activity levels, provided the essential information on which this work is based. T. Luera and G. Can0 provided the encouragement and advice which kept the authors going. Our colleagues in other laboratories provided not only ideas and valuable advice, but also gave us reciprocal experimental data for the interlaboratory comparisons of spectra. In this area we particularly thank W. Sallee, J. Meason, and M. Flanders of the White Sands Missile Range, and C. Heimbach from the Aberdeen Proving Ground.

SNL RML recommended dosimetry cross section compendium

“…Spectrum adjustment at Sandia National Laboratories is done primarily with an enhanced version of the SAND-II methodology [11,26]. When the new cross section library was assembled for the reactions in use at the Sandia RML, 15 previously determined spectra [27] were re-analyzed. Integral parameters, such as the spectral index (SI) and hardness parameter (HP) (defined by Kelly [27]), were not significantly altered by the updated cross sections.…”

“…When the new cross section library was assembled for the reactions in use at the Sandia RML, 15 previously determined spectra [27] were re-analyzed. Integral parameters, such as the spectral index (SI) and hardness parameter (HP) (defined by Kelly [27]), were not significantly altered by the updated cross sections. The quality of the fits, in term.,, of smoothness and standard deviation of experimental versus calculated activity, was slightly worse for the updated cross sections, but acceptable.…”

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

“…This conversion represents the atomic weight of isotopic 58Ni, 57.93534635 gm/mole (a mass excess of A = -60225 keV = 0.064653645 amu), divided by Avogadro's number, 6.0221367 x 1023 atoms/mole.…”

“…The ASTM E-722 Standard has adopted a new definition for the hardness parameter HP [6] which has zero rather than 10 keV for the low energy integral limit. This means that the 1-MeV(Si) fluence is no longer equal to the product of the spectral shape parameter, SP, the hardness parameter, HP, and the fluence greater than 3-MeV, O3MeV' Note that the hardness parameter also depends upon the silicon displacement damage function that is used.…”