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Journal Articles

Spectroscopic and first-principles investigations of iodine species incorporation into ettringite; Implications for iodine migration in cement waste forms

Guo, B.*; Xiong, Y.*; Chen, W.*; Saslow, S. A.*; Kozai, Naofumi; Onuki, Toshihiko*; Dabo, I.*; Sasaki, Keiko*

Journal of Hazardous Materials, 389, p.121880_1 - 121880_11, 2020/05

Journal Articles

Apparent diffusion coefficients of Cs and I in hardened cement paste using mineral admixtures

Mihara, Morihiro; Harasawa, Shuichi*; Torii, Kazuyuki*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(1), p.15 - 23, 2019/06

Hardened cement pastes (HCPs) of water/cement ratio (W/C) 50% and 30% using fly ash (FA), blast furnace slag (BFS) and silica fume (SF) for 28 days were prepared. Apparent diffusion coefficients (D$$_{a}$$) of Cs and I in HCPs were obtained using electron probe microanalysis. For Cs, BFS and SF contributed to a reduction of D$$_{a}$$ for W/C=50% and 30%, respectively. For I, BFS reduced D$$_{a}$$ for W/C=50%, however a significant reduction in D$$_{a}$$ for W/C=30% was not observed. Using SF enhanced sorption of Cs on HCP, and using BFS slightly improved sorption of Cs on HCP. It was also confirmed that the pore structures of HCP using SF and BFS were connected by fine pores. It was therefore considered that using SF and BFS contributes to the reduction of D$$_{a}$$ in HCP.

Journal Articles

Hydrochemical influence of shotcrete used in underground facilities on groundwater chemistry; Proposal of the evaluation method by geochemical simulation code

Iwatsuki, Teruki; Shibata, Masahito*; Murakami, Hiroaki; Watanabe, Yusuke; Fukuda, Kenji

Doboku Gakkai Rombunshu, G (Kankyo) (Internet), 75(1), p.42 - 54, 2019/03

In order to clarify the influence of shotcrete in the underground facility on the groundwater chemistry, an in-situ closed test was conducted in the mock-up tunnel at the depth of 500 m. Brucite, Ettringite, Ca(OH) $$_{2}$$, Gibbsite, K$$_{2}$$CO$$_{3}$$, Na$$_{2}$$CO$$_{3}$$ $$cdot$$ 10H$$_{2}$$O, SiO$$_{2}$$ (a) and Calcite were identified as the dominant minerals affecting the water chemistry. Furthermore, the shotcrete constructed in the tunnel has a reaction capacity which can produce about 570 m$$^{3}$$ of alkaline groundwater (pH12.4) saturated with Ca(OH)$$_{2}$$. The estimation would improve the accuracy of prediction analysis of the long-term chemical influence of cement materials after the closure of the tunnel.

Journal Articles

Hydrogen gas measurements of phosphate cement irradiated during heat treatment

Irisawa, Keita; Kudo, Isamu*; Taniguchi, Takumi; Namiki, Masahiro*; Osugi, Takeshi; Nakazawa, Osamu

QST-M-16; QST Takasaki Annual Report 2017, P. 63, 2019/03

no abstracts in English

Journal Articles

Development of cement based encapsulation for low radioactive liquid waste in Tokai Reprocessing Plant

Matsushima, Ryotatsu; Sato, Fuminori; Saito, Yasuo; Atarashi, Daiki*

Proceedings of 3rd International Symposium on Cement-based Materials for Nuclear Wastes (NUWCEM 2018) (USB Flash Drive), 4 Pages, 2018/10

At TRP, LWTF was constructed as a facility for processing low radioactive liquid waste and solid waste generated at TRP, and a cold test is been carrying out. In this facility, initially, nitrate waste liquid after separation of nuclides generated with treatment of low radioactive liquid waste was to be solidified by using borate. However, at present, it is necessary to decompose the nitrate in the liquid waste to reduce the environmental burden. For the reason, as a plan to replace the nitrate with the carbonate and to make it as a cement based encapsulation, we are studying for the introduction of the facility. Currently, as a cement solidification technology development for this liquid waste, we are studying the application of cement material based on blast furnace slag (BFS) as a main component. In this report, we show the results of the test conducted on the actual scale (200 L drum can scale).

JAEA Reports

Investigation and evaluation of sorption and diffusion data for sedimentary rocks and cementitious materials (Report on NUMO-JAEA collaborative research in FY2016-2017) (Joint research)

Hamamoto, Takafumi*; Matsubara, Ryuta*; Shibutani, Sanae*; Suyama, Tadahiro*; Tachi, Yukio

JAEA-Data/Code 2017-014, 31 Pages, 2018/03

JAEA-Data-Code-2017-014.pdf:2.1MB
JAEA-Data-Code-2017-014-appendix(CD-ROM).zip:0.61MB

NUMO and JAEA have developed the methodology of post-closure safety assessment for the geological disposal. For this purpose, NUMO and JAEA have conducted a collaborative research project for developing the safety assessment methodology based on international state of the art knowledge. The present report focuses on investigation of sorption and diffusion data reported and their QA evaluation for updating sorption and diffusion database (SDB and DDB) as the collaborative research project between NUMO and JAEA. This report includes sorption and diffusion data for mainly sedimentary rocks and cement materials. As a result, 1,746 sorption data from 19 references and 593 diffusion data from 25 references were extracted and prepared in the datasheet of SDB and DDB.

Journal Articles

Characterization of phosphate cement irradiated by $$gamma$$-ray during dehydration

Irisawa, Keita; Kudo, Isamu*; Taniguchi, Takumi; Namiki, Masahiro*; Osugi, Takeshi; Nakazawa, Osamu

QST-M-8; QST Takasaki Annual Report 2016, P. 63, 2018/03

A solidification technique with minimized water content is being developed using a phosphate cement for safe storage of secondary radioactive wastes in the Fukushima Daiichi Nuclear Power Plant. To understand the applicability of the solidification technique for the actual secondary wastes, phosphate cement during dehydration was irradiated by $$^{60}$$Co $$gamma$$-ray. The G(H$$_{2}$$) for the phosphate cement decreased with time during dehydration, and was not detected after 7 days. Moreover, the $$^{60}$$Co $$gamma$$-ray irradiation during dehydration did not change the crystalline and amorphous phases of the phosphate cement.

Journal Articles

Study on hydrogen generation from cement solidified products loading low-radioactive liquid wastes at Tokai Reprocessing Plant

Ito, Yoshiyuki; Matsushima, Ryotatsu; Sato, Fuminori

QST-M-8; QST Takasaki Annual Report 2016, P. 69, 2018/03

no abstracts in English

Journal Articles

Investigation of hydrogen gas generation by radiolysis for cement-solidified products of used adsorbents for water decontamination

Sato, Junya; Kikuchi, Hiroshi*; Kato, Jun; Sakakibara, Tetsuro; Matsushima, Ryotatsu; Sato, Fuminori; Kojima, Junji; Nakazawa, Osamu

QST-M-8; QST Takasaki Annual Report 2016, P. 62, 2018/03

no abstracts in English

Journal Articles

The Development of extra high head pump for cutoff grout drainage in a deep vertical shaft

Shirase, Mitsuyasu*; Abe, Akimasa*; Nago, Makito*; Ishii, Eiichi; Aoyagi, Kazuhei; Wakasugi, Shinichi*

Doboku Gakkai Heisei-29-Nendo Zenkoku Taikai Dai-72-Kai Nenji Gakujutsu Koenkai Koen Gaiyoshu (DVD-ROM), p.1795 - 1796, 2017/09

JAEA has executed the underground facility construction operation from February 2011 to June 2014, while carrying out the maintenance and research project until 2018. This report is about the extra high head pump which was able to drain the high specific gravity grout drainage, which develops during grouting operation at this facility, directly from 250m underground to the surface.

Journal Articles

Long-term mechanical analysis code considering chemical alteration for a TRU waste geological repository

Mihara, Morihiro; Hirano, Fumio; Takayama, Yusuke; Kyokawa, Hiroyuki*; Ono, Shintaro*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 24(1), p.15 - 25, 2017/06

A computer program MACBECE has been developed to provide rigorous calculations of the long-term mechanical behavior of a TRU waste geological repository. Consideration is given to the expected chemical alteration of repository components, including cementitious materials and bentonite, and the mechanical interactions between repository and host rock. The long-term mechanical behavior of a TRU waste repository was evaluated in a deep soft rock site, where creep deformation is likely to occur from the initial construction phase to 10$$^{5}$$ years after repository closure. It was found that the stress didn't fall into a singularity of yield surface of the EC model applied to the mechanical behavior model of bentonite. The calculated displacement of the inner diameter of the repository, considering mechanical interaction between repository and host rock, was about half that of a result in 2nd progress report on R&D for TRU waste disposal in Japan.

JAEA Reports

Basic properties of the concrete using the low alkaline cement (HFSC) developed by JAEA

Seno, Yasuhiro*; Nakayama, Masashi; Sugita, Yutaka; Tanai, Kenji; Fujita, Tomoo

JAEA-Data/Code 2016-011, 164 Pages, 2016/11

JAEA-Data-Code-2016-011.pdf:8.45MB
JAEA-Data-Code-2016-011-appendix(CD-ROM).zip:0.1MB

The cementitious materials are used as candidate materials for the tunnel support of the deep geological repository of high-level radioactive wastes (HLW).Generally the pH of leachate from concrete mixed Ordinary Portland Cement (OPC) shows a range of 12 to 13. The barrier function of bentonite used as a buffer material and that of host rock might be damaged by the high alkaline leachate from cementitious materials. Therefore, low alkalinity that does not damage each barrier function is necessary for cementitious materials used for the tunnel support system of the HLW geological repository. JAEA has developed a low alkaline cement named as HFSC (Highly Fly-ash contained Silicafume Cement) which the pH of the cement leachate could lower approximately 11. We have confirmed the applicability of HFSC for the tunnel support materials, by using experimentally as the shotcreting materials to the part of gallery wall at 140m, 250m and 350m depth in Horonobe Underground Research Laboratory. And moreover, HFSC has been used as the cast-in-place concrete for the shaft lining concrete at the depth of 374m-380m. This Data/Code summarized the past HFSC mix proportion test results about the fresh concrete properties and hardened concrete properties, in order to offer the information as a reference for selecting the mix proportion of HFSC concrete adopted to the disposal galleries et al. in the future.

JAEA Reports

Long-term immersion experiments of low alkaline cementitious materials

Seno, Yasuhiro*; Noguchi, Akira*; Nakayama, Masashi; Sugita, Yutaka; Suto, Shunkichi; Tanai, Kenji; Fujita, Tomoo; Sato, Haruo*

JAEA-Technology 2016-011, 20 Pages, 2016/07

JAEA-Technology-2016-011.pdf:7.56MB

Cementitious materials are expected to be used for the construction of an underground repository for the geological disposal of radioactive wastes. Ordinary Portland Cement(OPC) would conventionally be used in the fields of civil engineering and architecture, however, OPC has the potential to generate a highly alkaline plume (pH$$>$$12.5), which will likely degrade the performance of other barriers in the repository such as the bentonite buffer and/or host rock. Low alkaline cementitious materials are therefore being developed that will mitigate the generation of a highly alkaline plume. JAEA has developed a High-volume Fly ash Silica fume Cement (HFSC) as a candidate low alkaline cementitious material. The workability of the HFSC shotcrete was confirmed by conducting In-situ full scale construction tests in the Horonobe underground research laboratory. This report summarizes the results of immersion tests to assess the long-term pH behavior of hardened HFSC cement pastes made with mix designs that are expected to be able to be used in the construction of an underground repository in Japan.

JAEA Reports

User's guide of cement solidification test for incinerated ash

Nakayama, Takuya; Kawato, Yoshimi; Osugi, Takeshi; Shimazaki, Takejiro; Hanada, Keiji; Suzuki, Shinji; Sakakibara, Tetsuro; Nakazawa, Osamu; Meguro, Yoshihiro

JAEA-Technology 2014-046, 56 Pages, 2015/03

JAEA-Technology-2014-046.pdf:7.61MB

The combustible and flame-retardant radioactive wastes generated as a result of the research activities in Japan Atomic Energy Agency (JAEA) are incinerating to reduce their volume. The incinerated ash is planned to be solidified using cement for disposal. Since the properties of ashes generated in each institute of JAEA are varied with the type of incinerator and the wastes to be incinerated, it is necessary to do fundamental solidification tests in each institute to decide operating conditions of the planning cement solidification facility. It is important to standardize evaluating methods of cement and solidified waste because some characters depend on measuring method. This user's guide have been prepared how to decide the cement solidifying conditions of ash to design the cement solidification facility in JAEA. Requirements on the regulations of solidified radioactive waste have been examined and seven technical criteria, e.g. compressive strength, fluidity, have been selected as characters to be evaluated. Some empirical notes about selection of cement, admixtures, procedure on making a test piece, evaluation of expanding, compressive strength, solubility have been described. The strategy of tests and tips for finding optimized solidification condition has been summarized. Finally the example of optimized conditions satisfied the requirements and some problems to be solved have been described.

Journal Articles

Analytical surveillance on production methods of homogeneous and uniform solid materials from spent ion exchange residuum after ion coupled plasma volume-reduction process

Otani, Hiroshi; Mizui, Hiroyuki; Higashiura, Norikazu; Bando, Fumio*; Endo, Nobuyuki*; Yamagishi, Ryuichiro*; Kume, Kyo*

Heisei-25-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 16, P. 66, 2014/10

no abstracts in English

Journal Articles

Dissolution behavior of slag in cement-equilibrated aqueous solutions

Maeda, Toshikatsu; Bamba, Tsunetaka*; Mizuno, Tsuyoshi*; Terakado, Shogo; Kitagawa, Isamu; Numata, Masami

Haikibutsu Gakkai Rombunshi, 17(4), p.271 - 281, 2006/07

no abstracts in English

Journal Articles

Dissolution behavior of slag in the presence of cement

Maeda, Toshikatsu; Bamba, Tsunetaka*; Hotta, Katsutoshi*; Mizuno, Tsuyoshi*; Ozawa, Tatsuya

Nippon Genshiryoku Gakkai Wabun Rombunshi, 4(4), p.242 - 247, 2005/12

no abstracts in English

Journal Articles

Long-term alteration of bentonite; For safety evaluation of deep geological disposal

Tanaka, Tadao; Sakamoto, Yoshifumi; Yamaguchi, Tetsuji; Takazawa, Mayumi; Akai, Masanobu; Negishi, Kumi; Iida, Yoshihisa; Nakayama, Shinichi

JAERI-Conf 2005-007, p.105 - 110, 2005/08

Highly alkaline environments induced by cementitious materials in radioactive waste repositories are likely to dissolve and to alter montmorillonite, the main constituent of bentonite buffer materials. For the prediction of the long-term variations in permeability of compacted sand-bentonite mixtures, long-term alteration of bentonite should be quantified based on information accumulated by using the compacted or powdered bentonite materials, with batch experiments or column experiments. In this study, we summarize distinctive information obtained from various experimental systems, and propose functional and effective integration of experimental approaches to prediction of bentonite alteration.

Journal Articles

Experimental and modeling study to predict long-term alteration of bentonite buffer materials with alkaline groundwater

Takazawa, Mayumi; Negishi, Kumi; Sakamoto, Yoshifumi; Akai, Masanobu; Yamaguchi, Tetsuji; Iida, Yoshihisa; Tanaka, Tadao; Nakayama, Shinichi

JAERI-Conf 2005-007, p.236 - 241, 2005/08

no abstracts in English

Journal Articles

Field tests on migration of TRU-nuclide, 2; Migration test for engineered barrier materials in aerated soil

Maeda, Toshikatsu; Tanaka, Tadao; Mukai, Masayuki; Ogawa, Hiromichi; Yamaguchi, Tetsuji; Munakata, Masahiro; Matsumoto, Junko; Kozai, Naofumi; Bamba, Tsunetaka; Fan, Z.*; et al.

Nippon Genshiryoku Gakkai Wabun Rombunshi, 2(3), p.336 - 341, 2003/09

no abstracts in English

134 (Records 1-20 displayed on this page)