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Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.
Journal of Environmental Radioactivity, 238-239, p.106721_1 - 106721_10, 2021/11
Times Cited Count：11 Percentile：56.59(Environmental Sciences)This study was aimed at analysing performance of models for radiocesium migration mainly in evergreen coniferous forest in Fukushima, by inter-comparison between models of several research teams. The exercise included two scenarios of countermeasures against the contamination, namely removal of soil surface litter and forest renewal, and a specific konara oak forest scenario in addition to the evergreen forest scenario. All the models reproduced trend of time evolution of radiocesium inventories and concentrations in each of the components in forest such as leaf and organic soil layer. However, the variations between models enlarged in long-term predictions over 50 years after the fallout, meaning continuous field monitoring and model verification/validation is necessary.
and 
X-ray diffractions of corrosion products freshly formed on the surface of an iron-silicon alloySuzuki, Shigeru*; Matsubara, Eiichiro*; Komatsu, Takuya*; Okamoto, Yoshinori*; Kanie, Kiyoshi*; Muramatsu, Atsushi*; Konishi, Hiroyuki; Mizuki, Junichiro; Waseda, Yoshio*
Corrosion Science, 49(3), p.1081 - 1096, 2007/03
Times Cited Count：32 Percentile：80.42(Materials Science, Multidisciplinary) X-ray diffraction measurements of a small amount of samples extracted from wet corrosion products freshly formed on a pure iron and iron-2 mass% silicon surfaces have been conducted using synchrotron radiation. The results showed that 
-FeOOH was formed on the outer side of wet corrosion products formed on the pure iron by sodium chloride solution, while -FeOOH, 
-FeOOH, Fe
O
, and green rusts were formed on the inner side. In comparison to the case of the pure iron, a significant formation of 
-FeOOH was observed in the iron-silicon alloy. Furthermore, in-situ diffraction measurements by a conventional X-ray source were conducted for analyzing corrosion products formed on the pure iron and iron-silicon alloy surfaces by cyclic exposure to wet and dry atmospheres. The results obtained by the diffraction and 
diffraction measurements on the corrosion products were consistent.
Hirai, Keizo*; Komatsu, Masafumi*; Akama, Akio*; Noguchi, Ryotaro*; Nagakura, Junko*; Ohashi, Shinta*; Saito, Tetsu*; Kawasaki, Tatsuro*; Yazaki, Kenichi*; Ikeda, Shigeto*; et al.
no journal, ,
no abstracts in English
Matsuoka, Toshiyuki; Komatsu, Tetsuya; Yasue, Kenichi; Onoe, Hironori; Oyama, Takuya; Iwatsuki, Teruki; Sasao, Eiji; Umeda, Koji
no journal, ,
This paper summarized the current status of R&D activities with development of geological-evolutionary model in the Horonobe area, northern Hokkaido. This study has been carried out in the area of approx. 100 km 
30 km. Two stages, approx. 1 Ma and 0.33 Ma were selected for paleo-geological modeling based on geological history of several millions of years in and around the study area. 3D steady-state groundwater flow simulations and sensitivity analysis using these models were carried out. Long-term evolution of groundwater flow conditions caused by long-term geological phenomena was assessed using statistical analysis. From the results, the spatial distribution of long-term stability of groundwater flow conditions were estimated and important factors for assessment of long-term evolution of groundwater flow conditions were extracted. In addition, the results of groundwater flow simulation were analyzed from the viewpoint of geochemical environment within the groundwater.
Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.
no journal, ,
We applied modelling approaches to evaluate the past and future dynamics of 
Cs in forests. In the model inter-comparison exercise using Fukushima data, six models with diverse model structures, processes, parameters and numerical approaches joined this exercise and the performance and uncertainties of the state-of-the-art models were explored. The inter-comparison revealed that, after appropriate calibration, the models reproduced the observed data reliably and the ranges of calculated trajectories were narrow in the early phase after the fallout. However, the envelope of the calculated model end points enlarged in long-term simulations over 50 years after the fallout. The model-inter comparison exercise emphasizes the importance of decadal data for various forest types and repetitive verification/validation processes using holistic, long-term data to improve the models and to update the forecasting capacity of the models.
