Nuclear Analysis of Bulk Shielding Fusion Integral Experiments on Large SS316/Water Assembly with Simulated Super Conducting Magnet

As part of a collaboration with Japan, the U.S. participated in several fusion integral experiments that simulate the design features of the shielding blanket of the International Thermonuclear 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. For that purpose, JAERI has constructed a cylindrical test assembly of dimension 1.2 D × 1.2 L m and made of front multi-layers of SS316 and water with an embedded smaller zone consists of multi-layers of super conducting magnet (SCM) stimulant 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#l), 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) continuous 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,α)Na-24, In-115(n,n)In-115m, Au-197(n, γ)Au-198, and B-10(n,α)Li-7, (c) fission rate U-235(n,f) and U-238(n,f). (d) gamma-ray spectrum, and (e) gamma-ray heating rate.