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Neutron spectra from materials used in fusion and fusion--fission hybrid reactors

Conference ·
OSTI ID:6380713

The neutron leakage spectra from pulsed spheres of Cu (1.0, 3.0, and 5.0 mean-free-path, mfp), Nb (1.0 and 3.0 mfp), /sup 232/Th (1.0 mfp) and /sup 238/U (0.8 and 2.8 mfp) have been measured using time-of-flight techniques. The neutron spectra from the above materials used in fusion hybrid reactors have been measured between 0.8 and 14 MeV using a stilbene scintillator, pulse shape discrimination and flight paths of around 10 meters. The measured spectra are compared with calculations carried out with TARTNP, a coupled neutron-photon Monte-Carlo transport code. The Lawrence Livermore Laboratory neutron and photon cross sections library (ENDL) and the ENDF/B-IV library have been used in these calculations. The calculated neutron spectra using the ENDL library are in fair agreement with the measurements (5 to 10% discrepancies for the 1-mfp spheres). Calculations for Cu, Nb and Th carried out with the ENDF/B-IV library, badly underestimate the neutron emission between 5 and 10 MeV. The discrepancies with the measurements in this energy region are as large as a factor of two. In order to facilitate the use of these data for calculational purposes by other laboratories, one-dimensional ''experimental'' neutron energy spectra have been generated for each of the above measurements and are available upon request.

Research Organization:
California Univ., Livermore (USA). Lawrence Livermore Lab.
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
6380713
Report Number(s):
UCRL-81092; CONF-780921-8
Country of Publication:
United States
Language:
English