Measurement of 237Np fission rate ratio relative to 235U fission rate in cores with various thermal neutron spectrum at the Kyoto University Critical Assembly

Hironobu Unesaki, Tomohiko Iwasaki, Takanori Kitada, Akio Kohashi, Daisuke Fujiwara, Mitsuo Kuroda, Takeshi Kato, Yoshitaka Ikeuchi, Seiji Shiroya

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Integral measurements of 237Np fission rate ratio relative to 235U fission rate have been performed at Kyoto University Critical Assembly. The fission rates have been measured using the back-to-back type double fission chamber at five thermal cores with different H/235U ratio so that the neutron spectra of the cores were systematically varied. The measured fission rate ratio per atom was 0.00439 to 0.0298, with a typical uncertainty of 2 to 3%. The measured data were compared with the calculated results using SRAC/TWOTRAN and MVP based on JENDL-3.2, which gave the averaged C/E values of 0.93 and 0.95, respectively. Obtained results of C/E using 237Np cross sections from JENDL-3/2, ENDF/B-VI.5 and JEF2.2 show that the latter two gave smaller results than JENDL-3.2 by about 4%, which clearly reflects the discrepancy in the evaluated cross section among the libraries. This difference arises from both fast fission and resonance region. Although further improvement is recommended, 237Np fission cross section in JENDL-3.2 is considered to be superior to those in the other libraries and can be adopted for use in design calculations for minor actinide transmutation system using thermal reactors with prediction precision of 237Np fission rate within 10%.

Original languageEnglish
Pages (from-to)627-635
Number of pages9
Journaljournal of nuclear science and technology
Volume37
Issue number8
DOIs
Publication statusPublished - 2000 Aug

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering

Fingerprint Dive into the research topics of 'Measurement of <sup>237</sup>Np fission rate ratio relative to <sup>235</sup>U fission rate in cores with various thermal neutron spectrum at the Kyoto University Critical Assembly'. Together they form a unique fingerprint.

Cite this