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Subekti, M.*; Kudo, Kazuhiko*; Nabeshima, Kunihiko; Takamatsu, Kuniyoshi
Atom Indonesia, 43(2), p.93 - 102, 2017/08
Reactor kinetics based on point kinetic model have been generally applied as the standard method for neutronics codes. As the central control rod (C-CR) withdrawal test has demonstrated in a prismatic core of HTTR, the transient calculation of kinetic parameter, such as reactivity and neutron fluxes, requires a new method to shorten calculation-process time. Development of neural network method was applied to point kinetic model as the necessity of real-time calculation that could work in parallel with the digital reactivity meter. The combination of TDNN and Jordan RNN, such as TD-Jordan RNN, was the result of the modeling approach. The application of TD-Jordan RNN with adequate learning, tested offline, determined results accurately even when signal inputs were noisy. Furthermore, the preprocessing for neural network input utilized noise reduction as one of the equations to transform two of twelve time-delayed inputs into power corrected inputs.
Sugawara, Takanori; Zolbadral, T.*; Nishihara, Kenji; Tsujimoto, Kazufumi
Atom Indonesia, 38(2), p.71 - 77, 2012/08
An accelerator-driven system (ADS) has been investigated to transmute minor actinide (MA) included in high-level waste. In the neutronic design of the ADS, the accuracy of nuclear data for MA and lead bismuth (LBE) which is the candidate material for coolant and spallation target, is important. To know the current accuracy of nuclear data libraries, this study aims to compare representative nuclear data libraries, JENDL-4.0, 3.3, ENDF/B-VII.1 and VII.0 through the neutronic calculation of the ADS geometry proposed as the IAEA benchmark problem. The calculation results showed that about 1.1%dk difference was observed between JENDL-4.0 and ENDF/B-VII.1 at the beginning of cycle. These results mean that the current nuclear data libraries are still insufficient for the neutronic design of the ADS. The enhancement of nuclear data libraries by cross section measurement is required and, moreover, integral experiments with MA and LBE isotopes are essential.
Nakamura, Mitsutaka; Nakajima, Kenji; Inamura, Yasuhiro; Kawamura, Seiko; Kikuchi, Tatsuya; Otomo, Toshiya*; Arai, Masatoshi
Atom Indonesia, 36(3), p.116 - 120, 2010/12
We are now ready for the breakthrough of scientific activities on solid state ionic materials by making full use of both high neutron flux realized at Japan Proton Accelerator Research Complex (J-PARC) and our novel experimental technique. In this study, some experimental results on superionic conductors by inelastic neutron scattering measurements will be shown. The applicability and its expected contribution of new experimental technique into the further progress of scientific activities in solid state ionic materials will be also discussed.
Sakuma, Takashi*; Mohapatra, S. R.*; Uehara, Hiroyuki*; Sakai, Ryutaro*; Xianglian*; Takahashi, Haruyuki*; Igawa, Naoki; Basar, K.*
Atom Indonesia, 36(3), p.121 - 124, 2010/12
Diffuse neutron scattering measurement on Cu crystals was performed at 10 K and 300 K and the observed diffuse scattering intensities were analyzed by including the correlation effects among thermal displacements of atoms in the theory. Using the values of correlation effects among neighboring atoms and the values of Debye-Waller temperature parameter, force constants among first, second and third nearest neighboring atoms had been evaluated. The estimated values of force constants among first, second and third nearest neighboring atoms of Cu were 5.58, 3.63 and 2.37 eV/
at 300 K, respectively. The relation between correlation effects and the inter-atomic distance is not depending much on the crystal binding types.
