Delayed neutron spectra decay group for fissioning systems from /sup 227/Th through /sup 255/Fm

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7124294

England, T R; Brady, M C

Most applications of delayed neutrons use an approximate temporal group representation of measured aggregate data. Such data have been limited to the few fissioning nuclides that have aggregate measurements, and even these have inadequate or no spectral measurements. Improvements in the experimental techniques of isotope separation and neutron spectroscopy have made the study of delayed neutron emission from individual precursor nuclides more practical and productive over the past fifteen or so years. The quantity and quality of the delayed neutron emission probabilities and particularly the neutron emission spectra for the individual nuclides have been greatly improved. This paper will briefly review a recently completed evaluation of precursor data that comprises the largest single set of such data to date, and will also describe how the precursor data has been used to produced delayed neutron yields, halflives, and spectra in the classical six-group representation for 43 fissioning systems from /sup 227/Th to /sup 225/Fm. Comments and observations made concerning the use of more than six time groups will also be included. The application of the data in both its explicit and reduced (six temporal group representation) forms in the point reactor kinetics equations will also be discussed. Results from beta-effective calculations in a simple Godiva-type system will be presented, but the paper will concentrate on the data base and its few-group representations. 17 refs., 1 fig., 1 tab.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36; AC05-84OR21400
• OSTI ID: 7124294
• Report Number(s): LA-UR-88-626; CONF-880911-4; ON: DE88006459
• Country of Publication: United States
• Language: English

Related Subjects

652020* -- Nuclear Properties & Reactions
A=220 & above
Experimental
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYONS
DELAYED NEUTRONS
ELEMENTARY PARTICLES
FERMIONS
FISSION NEUTRONS
FISSIONABLE MATERIALS
HADRONS
MATERIALS
NEUTRON DENSITY
NEUTRON SPECTRA
NEUTRON SPECTROSCOPY
NEUTRONS
NUCLEONS
SPECTRA
SPECTROSCOPY
TABLES
TIME DEPENDENCE