Measurement and analysis of fission rate distributions of 237Np and 238u in a polyethylene system with a 65 mev neutron source

Tomohiko Iwasaki, Oshimasa Sakuya, Naohiro Hirakawa, Hiroshi Nakashima, Yukio Sakamot, Hiroshi Takada, Susumu Tanaka

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2 Citations (Scopus)


Fission rates of 237Np and 238U in a polyethylene (CH2) system were measured with a 65MeV quasi monoenergetic neutron source. Relative fission rate distributions dependent on polyethylene thickness up to about 70 cm were obtained for both nuclides with the experimental error within 7%. The present experiment was analyzed by the NMTC/JAERI code that has been employed for designing accelerator-driven transmutation systems. The fission rates of both 237Np and 238U calculated by the NMTC/JAERI did not agree with the experimental ones. The C/E values for both were about 2.0 at 71.8cm of polyethylene thickness when both experimental and calculated values were normalized to 1.0 at 0.0 cm of polyethylene thickness. A sensitivity analysis of the NMTC/JAERI was performed by changing cross sections and angular distributions of hydrogen and carbon and by employing three options of the intra-nuclear cascade/evaporation calculation of the NMTC/JAERI. The disagreement of the NMTC/JAERI calculation with the experimental values was partially improved by increasing the nonelastic-scattering cross section of carbon and by broadening the elastic-scattering angular distribution of carbon.

Original languageEnglish
Pages (from-to)169-177
Number of pages9
Journaljournal of nuclear science and technology
Issue number3
Publication statusPublished - 1998 Mar


  • Accelerator-driven reactor
  • Carbon
  • Errors
  • Experimental data
  • Fission rate
  • Hydrogen
  • MeV range 10-100
  • Neptunium 237
  • Neutron sources
  • Neutrons
  • Polyethylene
  • Transmutation
  • Uranium 238

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering


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