Re-investigations of integral neutron multiplication experiments with 14 MeV neutrons in lead

AbstractIn the present paper we report our analysis of neutron multiplication experiments with 14 MeV neutrons in lead. The benchmark experiments of Dresden (Atomkernenergie Kerntech. 49 (1987) 121) and Osaka (Proc. 12th SOFT, vol. 1, Pergamon, Oxford, 1982, pp. 687–692; Proc. Int. Symp. Fast Neutron in Science and Technology, Chiang Mai University, Thailand, 1985) are considered in this paper. New results of the analysis of these benchmark experiments using FENDL-2.0 (Fusion Evaluated Nuclear Data Library-2.0, FENDL/E-2.0, IAEA-NDS-175, Rev. 3, October 1998; Fusion Evaluated Nuclear Data Library CDROM, IAEA-NDS-CD-6; Report on an IAEA Consultants Meeting, 1998, IAEA, Vienna, Report INDC(NDS)-395, 1999), JENDL-3.2 (Nucl. Sci. Technol. 32 (1995) 1295) and JEF-2.2 (Proc. Int. Conf. Nuclear Data for Science and Technology, vol. 2, Gatlinburg, TN, 1994, p. 680) are presented here. Results available in the literature are critically examined and reviewed. The paper presents a comparison of basic measured data of the (n, 2n) cross-sections with the values recommended for applications in various basic evaluated nuclear data files for lead. Our analysis of the benchmark experiments with older data files such as ENDF/B-IV (ENDF/B-IV Summary Documentation, BNL-17541, 2nd ed., 1975) and ENDF/B-V (ENDF/B-V Summary Documentation, BNL-NCS-17541, 3rd ed., 1979) reproduced the published calculation results for these experiments. The values of neutron multiplication for spheres of radii 3, 6, 9 and 12 cm in the energy range 0.017–15 MeV are 1.218, 1.403, 1.54 and 1.634, respectively, with the use of FENDL-2.0. These values are lower than the experimentally observed value in the range of 5–10%. The calculated neutron multiplication values from the latest available data like FENDL-2.0, JENDL-3.2 and JEF-2.2 also give a value lower than the experimentally observed ones in the range of 5–10%. The older evaluated nuclear data like ENDF/B-IV and ENDF/B-V reproduce the published results which underpredict in the range 10–20%. It is also observed that the old and new data files cannot reproduce the neutron leakage spectrum for these benchmark experiments.