Overview of straight duct streaming experiments for ITER

Two straight duct streaming experiments for international thermonuclear exp erimental reactor (ITER) were performed by using the intense deuterium-trit ium (D-T) neutron source at Japan Atomic Energy Research Institute (JAERI) in order to investigate the influence of streaming through ducts on radiati on dose and to validate the accuracy of design calculations. One was a smal l duct streaming experiment for diagnostic ports, the other was a large duc t streaming experiment for large ports such as neutral beam injector (NBI) port. The ducts increased the neutron flux above 10 MeV by 10(6)-10(7) time s at the ends of the ducts, while the increase of neutron flux below 10 MeV and gamma -ray by the ducts was less than a few hundred times. These exper iments were analyzed by the MCNP-4A code with three nuclear data libraries: FENDL/E-2.0, -1.0 and JENDL Fusion File. Though the ducts made complicated neutron and gamma -ray flux distributions in a cavity region, most of the calculated results agreed within +/- 40% with the experimental data. It was demonstrated that the MCNP calculations with the nuclear data libraries we re accurate enough for predicting nuclear design parameters of ITER even fo r Various duct geometries as far as they were modeled precisely. (C) 2000 E lsevier Science B.V. Ail rights reserved.