A Project focusing on the contamination mechanism of concrete after the accident at Fukushima Daiichi Nuclear Power Plant

Yamada, Kazuo*; Maruyama, Ippei*; Haga, Kazuko*; Igarashi, Go*; Aihara, Haruka; Tomita, Sayuri*; Kiran, R.*; Osawa, Norihisa*; Shibata, Atsuhiro; Shibuya, Kazutoshi*; et al.

Proceedings of International Waste Management Symposia 2021 (WM2021) (CD-ROM), 10 Pages, 2021/03

Quantification of water penetration into concrete through cracks by neutron radiography

Kanematsu, Manabu*; Maruyama, Ippei*; Noguchi, Takafumi*; Iikura, Hiroshi; Tsuchiya, Naoko*

Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.154 - 158, 2009/06

https://doi.org/10.1016/j.nima.2009.01.206

Visualization and quantification of water behavior around cracks by neutron radiography

Kanematsu, Manabu*; Noguchi, Takafumi*; Maruyama, Ippei*; Iikura, Hiroshi

Konkurito Kogaku Nenji Rombunshu (DVD-ROM), 29(1), p.981 - 986, 2007/00

Neutron radiography is one of the non-destructive methods. In this research, neutron radiography was applied to visualize and quantify the water penetration into concrete through cracks. The radiographs were obtained by the TNRF (Thermal Neutron Radiography Facility) installed at a research reactor, JRR-3M, in the Japan Atomic Energy Agency (JAEA). The quantitative capability of neutron radiography for the water content and the penetration depth in cement paste specimen were confirmed. The effects of crack and water content on the velocity and the depth of water penetration into concrete were visualized with several concrete specimens, to which surface water was supplied through the container.

Study on the radionuclide contamination mechanisms of concrete and the estimation of distribution of radionuclides, 3; Sorption behavior of alpha nuclides

Aihara, Haruka; Shibata, Atsuhiro; Koma, Yoshikazu; Tomita, Sayuri*; Maruyama, Ippei*

no journal, , 

no abstracts in English

Study on the radionuclide contamination mechanisms of concrete and the estimation of distribution of radionuclides, 10; Modeling of penetration behavior of Cs and Sr into concrete at turbine building basement of Fukushima Daiichi Nuclear Power Station

Tomita, Sayuri*; Kobayashi, Yutaro*; Haga, Kazuko*; Hosokawa, Yoshifumi*; Yamada, Kazuo*; Aihara, Haruka; Igarashi, Go*; Maruyama, Ippei*

no journal, , 

no abstracts in English

Basic study on elucidation of the mechanism of concrete contamination and estimation of contamination distribution with radioactive materials; Experimental verification on effect of nature of concrete for migration of Cs and Sr

Maruyama, Ippei*; Shibuya, Kazutoshi*; Tomita, Sayuri*; Igarashi, Go*; Koma, Yoshikazu; Yamada, Kazuo*

no journal, , 

no abstracts in English

Study for self-sealing process of EDZ and flow-paths factures learnt from spherical carbonate concretion formation

Yoshida, Hidekazu*; Yamamoto, Koshi*; Maruyama, Ippei*; Karukaya, Koichi*; Nakayama, Masashi; Sakurai, Akitaka; Sato, Toshinori

no journal, , 

Spherical, isolated carbonate concretions occur throughout the world in marine argillaceous sedimentary rocks of widely varying geological ages. These concretions are characteristically highly enriched in CaCO compared to the surrounding sedimentary rock matrices and are commonly containing the well-preserved fossils inside. Recently the process of the enrichment of CaCO has been revealed and synthetic concretion materials are developed. Here we will introduce the in-situ experiment with the synthetic concretion material for EDZ sealing carried out in Horonobe Underground Research Laboratory and the preliminary results of the EDZ sealing process and their sealing effectiveness.

The Effects of cracks on the Cs and Sr penetration into concrete

Yamada, Kazuo*; Himori, Keita*; Tojo, Yasumasa*; Tomita, Sayuri*; Aihara, Haruka; Igarashi, Go*; Hosokawa, Yoshifumi*; Maruyama, Ippei*

no journal, , 

no abstracts in English

Study on the radionuclide contamination mechanisms of concrete and the estimation of distribution of radionuclides, 23; Penetration of alpha nuclides into hardened cement pastes simulating cracking

Aihara, Haruka; Hinai, Hiroshi; Koma, Yoshikazu; Tomita, Sayuri*; Maruyama, Ippei*

no journal, , 

At the Fukushima Daiichi Nuclear Power Plant, contaminated water has remained in the buildings, and alpha nuclides such as plutonium have been detected. Analysis results of contaminated water indicate that plutonium concentration is decreasing downstream, therefore there is concern that plutonium is remaining in the reactor buildings. To evaluate the depth of penetration of -nuclides into the wall surface of the building contacted with contaminated water, a sample consisting of two cement paste test pieces was immersed in simulated contaminated water. When the crack width was less than 0.1 mm, the penetration depth of -nuclides did not increase due to cracking and remained within 2 mm from the surface layer. On the other hand, the penetration of -nuclides increased significantly when the crack width was 0.5 mm or more, suggesting that the effect of cracks of about 0.1 mm, which is expected in normal operation, is small, whereas the formation of large cracks during an accident may result in the penetration of -nuclides.

Study on the radionuclide contamination mechanisms of concrete and the estimation of distribution of radionuclides, 26; Important factors for the contamination survey and estimation of concrete in Fukushima Daiichi NPP: cracks, aggregate, cement, competitive ions, dry-carbonation-Ca leaching, reversibility/irreversibility of ion adsorption

Yamada, Kazuo*; Maruyama, Ippei*; Shibuya, Kazutoshi*; Tojo, Yasumasa*; Aihara, Haruka; Hosokawa, Yoshifumi*; Igarashi, Go*; Koma, Yoshikazu

no journal, , 

no abstracts in English