Dogleg Diet Streaming Experiment with 14 MeV Neutron Source

There are several vacant channels for diagnosis, RF heating, etc. through the shielding structure in fusion reactors. Some of them consist of dogleg ducts, and the streaming effect has not been experimentally investigated yet. The present work was conducted to study the behavior of neutrons streaming through the ducts and estimate the uncertainties of calculations for the design of fusion reactors such as ITER on the basis of the experiments with the FNS facility at JAERI. The experimental assembly was an iron slab 180 cm in thickness. A doubly bent duct 30 cm X 30 cm in the cross section was shaped in the assembly The lengths of the 3 legs were 115 cm, 60 cm and 65 cm respectively The experiment was analyzed with the Monte Carlo transport calculation codes MCNP-4B, -4C, the nuclear data libraries FENDL-2 and JENDL-3.3. In the analysis, the calculated neutron spectra agreed with measured data within the statistical errors. The reaction rates for 93Nb(n,2n)92mNb and 115In(n,n’)115mIn showed relatively favo...