Study of calculated and measured time dependent delayed neutron yields. [TX, for calculating delayed neutron yields; MATINV, for matrix inversion; in FORTRAN for LSI-II minicomputer]

Technical Report · Thu May 01 04:00:00 EDT 1980

DOI:https://doi.org/10.2172/5217598· OSTI ID:5217598

Waldo, R W

Time-dependent delayed neutron emission is of interest in reactor design, reactor dynamics, and nuclear physics studies. The delayed neutrons from neutron-induced fission of /sup 232/U, /sup 237/Np, /sup 238/Pu, /sup 241/Am, /sup 242m/Am, /sup 245/Cm, and /sup 249/Cf were studied for the first time. The delayed neutron emission from /sup 232/Th, /sup 233/U, /sup 235/U, /sup 238/U, /sup 239/Pu, /sup 241/Pu, and /sup 242/Pu were measured as well. The data were used to develop an empirical expression for the total delayed neutron yield. The expression gives accurate results for a large variety of nuclides from /sup 232/Th to /sup 252/Cf. The data measuring the decay of delayed neutrons with time were used to derive another empirical expression predicting the delayed neutron emission with time. It was found that nuclides with similar mass-to-charge ratios have similar decay patterns. Thus the relative decay pattern of one nuclide can be established by any measured nuclide with a similar mass-to-charge ratio. A simple fission product yield model was developed and applied to delayed neutron precursors. It accurately predicts observed yield and decay characteristics. In conclusion, it is possible to not only estimate the total delayed neutron yield for a given nuclide but the time-dependent nature of the delayed neutrons as well. Reactors utilizing recycled fuel or burning actinides are likely to have inventories of fissioning nuclides that have not been studied until now. The delayed neutrons from these nuclides can now be incorporated so that their influence on the stability and control of reactors can be delineated. 8 figures, 39 tables.

• Research Organization: California Univ., Livermore (USA). Lawrence Livermore Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5217598
• Report Number(s): UCRL-52945
• Country of Publication: United States
• Language: English

Related Subjects

652026* -- Nuclear Properties & Reactions
A=220 & above
Experimental-- Spontaneous & Induced Fission-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDE ISOTOPES
AMERICIUM ISOTOPES
BARYON REACTIONS
BARYONS
CALIFORNIUM 249 TARGET
COMPUTER CODES
CURIUM 245 TARGET
DATA
DELAYED NEUTRONS
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
FISSION
FISSION NEUTRONS
FISSION YIELD
FORTRAN
HADRON REACTIONS
HADRONS
INFORMATION
ISOTOPES
M CODES
NEPTUNIUM 237 TARGET
NEUTRON REACTIONS
NEUTRONS
NUCLEAR REACTION YIELD
NUCLEAR REACTIONS
NUCLEON REACTIONS
NUCLEONS
NUMERICAL DATA
PILE NEUTRONS
PLUTONIUM ISOTOPES
PROGRAMMING LANGUAGES
T CODES
TARGETS
THORIUM 232 TARGET
TIME DEPENDENCE
URANIUM ISOTOPES
YIELDS