Comparison of 14 MeV isomer production of {sup 178m2}Hf and {sup 179m2}Hf using Feshbach-Kerman-Koonin and exciton preequilibrium models

Conference · Mon Nov 01 04:00:00 EST 1993

OSTI ID:10104062

Chadwick, M B ^[1]; Young, P G ^[2]

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1. Lawrence Livermore National Lab., CA (United States)
2. Los Alamos National Lab., NM (United States)

The {sup 178m2}Hf(16+) isomeric state has a 31-yr half life and could pose serious radioactive problems in nuclear fusion reactors if its production in 14 MeV neutron-induced reactions is significant. We present statistical/preequilibrium model calculations for the production of this isomer in the {sup 179}Hf(n, 2n) {sup 178m2}Hf reaction, as well as the 25-days 12.5{sup {minus}} isomer in the {sup 179}Hf(n,n{prime}){sup 179m2}Hf reaction, using two different preequilibrium models: the exciton model and the Feshbach-Kerman-Koonin (FKK) theory. Our calculations which use the exciton model agree well with measurements, but those with the FKK theory underestimate measurements. Our calculations axe the first to probe angular momentum transfer effects in the FKK theory and suggest that, as it is presently applied, high spin-transfer reactions are underestimated. We suggest modifications to the FKK statistical averaging procedure which may result in an improved agreement with experiment.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 10104062
• Report Number(s): LA-UR--93-3632; CONF-940459--2; ON: DE94002640
• Country of Publication: United States
• Language: English

Related Subjects

663430
663570
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700480
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
A = 150-189
COMPONENT DEVELOPMENT
CROSS SECTIONS
EXCITON MODEL
HAFNIUM 178
HAFNIUM 179
HAFNIUM 179 TARGET
HALF-LIFE
ISOMERIC TRANSITIONS
ISOTOPE PRODUCTION
MATERIALS STUDIES
MOMENTUM TRANSFER
NEUTRON REACTIONS
NUCLEON-INDUCED REACTIONS AND SCATTERING
PRECOMPOUND-NUCLEUS EMISSION
THERMONUCLEAR REACTOR MATERIALS