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Kato, Aitaro*; Saiga, Atsushi; Takeda, Tetsuya*; Iwasaki, Takaya*; Matsuzawa, Toru*
Earth, Planets and Space (Internet), 66(1), p.86_1 - 86_8, 2014/12
Times Cited Count：22 Percentile：55.47(Geosciences, Multidisciplinary)To understand the mechanism of an intensive non-volcanic seismic swarm in the Kii Peninsula, Japan, we used a dense seismic linear array to measure fine-scale variations of seismic velocities and converted teleseismic waves. A low-velocity anomaly confined to just beneath the seismic swarm area is clearly imaged, which spatially correlates with an uplifted surface area, and a highly conductive and strong attenuative body. These results suggest that fluids such as partial melt or water are present beneath this non-volcanic seismic swarm area. It is notable that the island arc Moho below the seismic swarm area is at depths of ca. 32 km in the northern part of the seismic swarm area, and shallows to ca. 20 km towards the south, due to an upwardly raised structure of serpentinized mantle wedge. In addition, we show that hydrated oceanic crust of the subducting Philippine Sea slab is characterized by low-velocities with a high Poisson's ratio at depths shallower than 40 km. Water released from the subducting oceanic crust could cause serpentinization of the mantle wedge and infiltration into the forearc base of the overlying plate. The interaction between dehydration of the subducting oceanic crust and hydration of the mantle wedge and overlying plate exerts an important role in driving the non-volcanic seismic swarm activity in the Kii Peninsula.
Szogradi, M.*; Nagaya, Yasunobu
no journal, ,
A new nodal diffusion solver Ants has been developed at VTT for the development of Generation IV reactor concepts. The two-step approach where group constants are generated via Monte Carlo (MC) methods is used for the reactor core analysis. To validate this approach, the JOYO MK-I core published in the International Handbook of Evaluated Reactor Physics Benchmark Experiments was analyzed. The Serpent Monte Carlo code was used to obtain group constants of the JOYO MK-I core. The Serpent few-group cross sections were then used as input data for Ants. Calculations were also carried out with Serpent and the MVP Monte Carlo code for a full-core 3D model to assess the general performance of the code comparing neutron spectrums and power spatial distributions. Results obtained with the 3D Ants JOYO model were compared with the MC results as the first assessment of the nodal diffusion solver with fast system.
Fujita, Tatsuya
no journal, ,
Past studies have mentioned that the treatment of implicit effect for cross-section perturbation affects the sensitivity coefficients and then the uncertainty analysis results for the k-infinity. The several approaches to consider the above implicit effect has also been discussed for the random-sampling-based uncertainty analysis. In this study, the influence due to implicit effect on typical nuclides and nuclear reactions in PWR 17
17 UO
and MOX fuel assemblies was confirmed prior to treat the implicit effect on the random-sampling-based uncertainty analysis in future studies. In the UO fuel assembly, the influence due to implicit effect on the k-infinity was small, thus the uncertainty quantification only considering the explicit effect would be applicable. On the other hand, further discussion about the influence due to implicit effect was necessary for the MOX fuel assembly.
