As part of on-going collaboration with Japan, the U.S. is participating in several fusion integral experiments that simulates the design features of the shielding blanket of the International Theromonuclear Experimental Reactor, ITER. The purpose of these efforts is to resolve the critical issues associated with the neutronics R&D tasks of ITER, among which is the adequacy of the newly developed FENDL-1 database and the up-to-date transport codes in predicting key neutronics parameters pertaining to personnel and magnet protection, among which is heat deposition in the SCM zone. For that purpose, JAERI has constructed a cylindrical test assembly of dimension 1.2 D x 1.2 L m and made of front multi-layers of SS316 and water with an embedded smaller zone consists of also multi-layers of SCM simulant and SS316. Measured parameters , covering the neutron energy range from 14 MeV down to thermal energy, were taken inside the SS316 and the SCM layers at 9 locations up to a depth of 91.4 cm. In one experiment (Assembly#1), a 1.27 cm B4C + 3.8 cm Pb layer was added in front of the SCM multi-layer zone. This layer is not included in Assembly#2. As in previous experiments, the 14 MeV source is housed inside a source reflector can (20 cm-thick) and located at a distance of 30 cm from the assembly. The U.S analysis reported here was performed with 175n-42g FENDL/MG-1.0 (multigroup) as well as ENDF/B-VI data using the DORT 2-D code. Analysis was also performed with the Monte Carlo (MC) continous energy data, FENDL/MC-1.0. The calculated parameters were compared to the following measured data: (a) neutron spectrum below 2 MeV, (b) foil activation rates such as Nb-93(n,2n)Nb-93m, Al-27(n,a)Na-24, In-155(n,n')In-115m, Au-197(n,g)Au-198, and B-10(n,a)Li-7, (c) fission rate U-235(n,f) and U-238(n,f), (d) gamma-ray spectrum, and (e) gamma-ray heating rate.

The high-threshold reaction Nb-93(n,2n) is sensitive to the integrated spectrum above 10 MeV and is well predicted within 2-15% of the experiments with an over-prediction, a trend that is reverse to what was found in previous experiments on SS316/water experiment. Similar accuracy (2-10% in Assembly#1 and 2-15% in Assemly#2) were obtained for the Al-27(n,a) and U-238(n,f) reactions. The calculated-to-experiment (C/E) values for the In-115(n,n') reaction are within 2-25% of the experiment, where over-prediction is observed behind the B4C/Pb layer in Assembly#1. The integrated spectrum in the range 0.1-1 MeV is within 10-25% in both assemblies and generally an over prediction is observed at deep location, a reverse trend to what was found in the SS316/water experiment. Large discrepancy was found for the integrated spectrum in the range 1-10 keV (C/E ~1.9) at deep locations but the experimental error are large (20-90%) at these locations. It is suspected that the integrated spectrum is under predicted below 1 eV as inferred by the B-10(n,a) reaction which is under predicted by 15-60%. This could be caused by the inaccuracy of the thermal group cross-section of FENDL/MG-1.0 data. Gamma-ray flux is well reproduced within the experimental error, except at energies above 10 MeV where large discrepancies are observed. The Gamma-ray heating rates are well predicted at front locations (within the experimental errors). However, there is an over estimation of ~20-25% at deep locations.