Updated ENDL99 Cross Sections for U(n.y) and U(n,f)

Brown, D ; Dietrich, F ; Hill, T ; McNabb, D

Lawrence Livermore National Laboratory

关键词: Uranium Isotopes;    Fission;    71 Classical And Quantum Mechanics, General Physics;    Neutrons;    Cross Sections;   

DOI  :  10.2172/15004658
RP-ID  :  UCRL-ID-148410
RP-ID  :  W-7405-ENG-48
RP-ID  :  15004658

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来源: UNT Digital Library

【 摘 要 】

In this note, we describe the first of two updates to the uranium isotopes in Livermore's Evaluated Neutron Data Library, ENDL99. Here, we concentrate on improving the (n, f) and (n, {gamma}) evaluations for a limited set of uranium isotopes. The first improvement consisted of creating an evaluation for {sup 232}U using a combination of fission and capture cross sections from the JENDL-3.2 database and the outgoing particle distributions from the exiting ENDL99 {sup 234}U evaluation. The second improvement consisted of updating existing (n, f) and (n, {gamma}) evaluations for uranium isotopes with A=233-238. These improvements are particularly apparent in the neutron resonance region as ENDL99 often contains gross averages over the resonances. We have propagated these updates into various Livermore application libraries.