Preliminary spectrum shifter design for intermediate energy nuclear data benchmark experiments with DT neutrons

Ota, Masayuki*; Kondo, Keitaro; Matsunaka, Masayuki*; Miyamaru, Hiroyuki*; Murata, Isao*; Iida, Toshiyuki*; Ochiai, Kentaro; Konno, Chikara  

In order to validate evaluated nuclear data libraries for fusion reactor designs, various integral benchmark experiments with DT neutrons have been carried out so far on structural and advanced blanket materials at the FNS facility of JAEA. In this study, a neutron spectrum shifter, which will be placed between a sample and the DT neutron source to moderate DT neutrons incident to the sample, was adopted in order to carry out the nuclear data benchmarking induced with several MeV neutrons effectively. In order to estimate effects of the spectrum shifter, the ratio of contribution of initial 14 MeV neutrons in leakage neutron and -ray spectra was calculated for the experimental configuration at FNS with a modified MCNP-4C code. The calculations were carried out for a LiTiO sample with a Be, LiD, or DO spectrum shifter. It was found that the Be shifter was superior to others and the contribution of initial 14 MeV neutrons varied depending on material and size of the sample and shifter. The present analysis also suggested that the Be shifter was effective for secondary -ray experiments.