Study on modeling and analysis of groundwater flow with inverse analysis, 2 (Joint research)

Onoe, Hironori; Yamamoto, Shinya*; Kohashi, Akio; Ozaki, Yusuke; Sakurai, Hideyuki*; Masumoto, Kiyoshi*

JAEA-Research 2018-003, 84 Pages, 2018/06

JAEA-Research-2018-003.pdf:17.44MB

In this study, numerical experiments considered hydrogeological structures, which has high heterogeneity around the Mizunami Underground Research Laboratory and inverse analysis using in-situ data were carried out. The results showed that concentration of hydrogeological structure to be estimated and location of monitoring point is important for application of inverse analysis. Furthermore, it is concluded that inverse analysis using hydraulic response due to pumping test is effective for hydrogeological characterization.

Groundwater flow modeling focused on the Fukushima Daiichi Nuclear Power Plant site

Saegusa, Hiromitsu; Onoe, Hironori; Kohashi, Akio; Watanabe, Masahisa

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company is facing contaminated water issues. The amount of contaminated water is continuously increasing due to groundwater leakage into the underground part of reactor and turbine buildings. Therefore, it is important to understand the groundwater flow conditions at the site and to predict the impact of countermeasures taken for isolating groundwater from the source of the contamination, i.e. the reactor buildings. Installations, such as of land-side and sea-side impermeable walls have been planned as countermeasures. In this study, groundwater flow modeling has been performed to estimate the response of groundwater flow conditions to the countermeasures. From the modeling, groundwater conditions and changes in response to implementation of the countermeasures could be reasonably estimated. The results indicate that the countermeasures will decrease the volume of inflow into underground part of the buildings. This means that the countermeasures will be effective in reducing the discharge volume of contaminated groundwater to ocean.

Inverse analysis methods for characterization of hydrogeological heterogeneity, 1; Numerical experiments with adjoint state method

Masumoto, Kiyoshi*; Onoe, Hironori; Kohashi, Akio; Yamamoto, Shinya*

no journal, , 

no abstracts in English

Inverse analysis methods for characterization of hydrogeological heterogeneity

Kohashi, Akio; Onoe, Hironori; Yamamoto, Shinya*; Honda, Makoto*; Sakurai, Hideyuki*; Masumoto, Kiyoshi*

no journal, , 

no abstracts in English

Estimation of hydraulic conductivity in fault zone by inversion of water head data

Ozaki, Yusuke; Kohashi, Akio; Onoe, Hironori; Yamamoto, Shinya*; Masumoto, Kiyoshi*

no journal, , 

The objective of this study is verification of feasibility to estimate hydraulic conductivity with inversion method of water head data in fault zone. Hydraulic conductivity in a fault zone is focused on as a target of inversion because the fault would significantly affect a water head field. A series of numerical test with synthetic model is performed under the condition that the number of fault to estimate hydraulic conductivity and the degree of freedom of hydraulic conductivity distribution in a fault zone is different. The information of hydraulic conductivity outside the faults and location of fault is given to the inversion a priori. Our inversion results shows that the accuracy of estimation is improved by constrain to the number of fault to estimate the hydraulic conductivity and freedom of hydraulic conductivity distribution in a fault. In addition, the number of fault to estimate the hydraulic conductivity should be limited for the certain estimation of hydraulic conductivity in all faults.

Mizunami Underground Research Laboratory Project; Study on groundwater recovery experiment; Water pressure change of groundwater during the water filling of the research gallery

Keya, Hiromichi; Takayasu, Kentaro; Kohashi, Akio; Onoe, Hironori; Takeuchi, Ryuji

no journal, , 

no abstracts in English

Mizunami Underground Research Laboratory Project, Study on groundwater recovery experiment; Hydrological investigation and analysis during temporal decompression test

Ozaki, Yusuke; Kohashi, Akio; Keya, Hiromichi; Onoe, Hironori; Takeuchi, Ryuji

no journal, , 

In Mizunami Underground Research Laboratory, groundwater recovery experiment test is performed at a part of research tunnel at 500m depth for research of recovery process of subsurface environment disturbed by construction of subsurface structure. During 2017, three times temporal decompression tests of hydraulic pressure in closure test drift keeping closed condition were conducted. We report the reproductivity of time variation of hydraulic pressure during the tests. We also report the estimation results of hydrogeological structure from the data during tests.