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Journal Articles

Vitrification technology for radioactive wastes

Amamoto, Ippei

Journal of the Society of Inorganic Materials, Japan, 24(391), p.393 - 401, 2017/11

Glass is a non-crystalline solid, as such, it is relatively easy to change its composition to control its characteristics. The borosilicate glass, which is produced by the addition of boron oxide into sodium-lime glass, possesses excellent heat-resistant properties and mechanical strength. It has a wide variety of uses. The borosilicate glass is applied as the vitrified medium for radioactive wastes to immobilize and stabilize them for long term. The glass form which is loaded with high-level radioactive waste is called the vitrified waste. This paper classified the radioactive waste and describes treatment and production methods of vitrified waste, its characteristics, disposal method and also introduces alternative vitrified medium.

Journal Articles

Research on vitrification technology to immobilize radioactive sludge generated from Fukushima Daiichi Power Plant; Enhanced glass medium

Amamoto, Ippei; Kobayashi, Hidekazu; Kitamura, Naoto*; Takebe, Hiromichi*; Mitamura, Naoki*; Tsuzuki, Tatsuya*; Fukayama, Daigen*; Nagano, Yuichi*; Jantzen, T.*; Hack, K.*

Journal of Nuclear Science and Technology, 53(10), p.1467 - 1475, 2016/10

 Times Cited Count:1 Percentile:84.49(Nuclear Science & Technology)

The iron phosphate glass (IPG) medium is known to be a high-efficiency glass medium, therefore we try to evaluate its applicability to immobilize sludge bearing radioactive nuclides arising from treatment of contaminated water at the stricken Fukushima Daiichi Nuclear Power Plant. For this study, many physical and chemical properties of target materials are necessary to evaluate the behaviours of IPG medium and its waste forms. Inevitably, it will entail the need for many and varied types of experiments to be carried out under high temperature. It is therefore rational to apply appropriate theoretical analysis first so as to reduce the number of experimental run. For this reason, some necessary thermodynamic values for theoretical analysis were estimated by CALPHAD approach followed by making up the calculated phase diagrams. By comparison with experimental results, they were found to be reliable for evaluating the behaviours of IPG medium and its waste forms.

Journal Articles

Containment of radioactive waste to glass; "Iron phasphate glass" for radioactive waste treatment

Tsuzuki, Tatsuya*; Mitamura, Naoki*; Amamoto, Ippei

Shakai, Kankyo Hokokusho 2014 (Internet), p.6 - 7, 2014/10

no abstracts in English

Journal Articles

Vitrification technology for immobilisation of high-level radioactive liquid waste; Research on higher-efficiency glass medium

Amamoto, Ippei

Nihon Gakujutsu Shinkokai Gokin Jotaizu Dai-172 Iinkai Kenkyu Hokokusho Vol.14 No.1, p.1 - 11, 2014/05

no abstracts in English

Journal Articles

Applicability of iron phosphate glass medium for loading NaCl originated from seawater used for cooling the stricken power reactors

Kobayashi, Hidekazu; Amamoto, Ippei; Yokozawa, Takuma; Yamashita, Teruo; Nagai, Takayuki; Kitamura, Naoto*; Takebe, Hiromichi*; Mitamura, Naoki*; Tsuzuki, Tatsuya*

Proceedings of 15th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2013) (CD-ROM), 6 Pages, 2013/09

no abstracts in English

Journal Articles

Behaviour of IPG waste forms bearing BaSO$$_{4}$$ as the dominant sludge constituent generated from the treatment of water used for cooling the stricken power reactors

Amamoto, Ippei; Kobayashi, Hidekazu; Yokozawa, Takuma; Yamashita, Teruo; Nagai, Takayuki; Kitamura, Naoto*; Takebe, Hiromichi*; Mitamura, Naoki*; Tsuzuki, Tatsuya*

Proceedings of 15th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2013) (CD-ROM), 8 Pages, 2013/09

The great amount of water used for cooling the stricken power reactors at Fukushima Dai-ichi has resulted in accumulation of "remaining water". As the remaining water is subsequently contaminated by FPs, etc., it is necessary to decontaminate it in order to reduce the volume of liquid radioactive waste and to reuse it again for cooling the reactors. Various techniques are being applied to remove FP, etc. and to make stable waste forms. One of the methods using the iron phosphate glass as a medium is being developed to stabilize the strontium-bearing sludge whose main component is BaSO$$_{4}$$. From the results hitherto, the iron phosphate glass is regarded as a potential medium for the target sludge.

Journal Articles

New loading glass for radioactive waste; Enhancement of its performance

Tsuzuki, Tatsuya*; Mitamura, Naoki*; Amamoto, Ippei

Mirai Zairyo, 12(10), p.43 - 47, 2012/10

no abstracts in English

Journal Articles

Treatment of high-level radioactive waste arising from pyroprocessing and its waste form

Amamoto, Ippei

Radioactive Waste; Sources, Types and Management, p.97 - 126, 2011/11

In this paper, the author has briefly introduced the development of pyroprocessing, highlighting the spent electrolyte treatment from the viewpoint of economical and environmental load reduction. The zeolite sorption method developed in USA is currently most progressive technique. There are other methods which use phosphates to treat the spent electrolyte, among them three are presented here, i.e., the phosphates precipitation method developed by RIAR, the GRSS method using SAP by KAERI, and the phosphate conversion method by JAEA. In the phosphate conversion method, the iron phosphate glass (IPG), which possesses unique properties, is employed for FP separation and FP immobilization. From preliminary experiments, it found that the IPG could separate insoluble FP in the spent electrolyte when used as a filtration medium. In addition, when used as a sorbent, it could remove the soluble FP. The IPG is regarded as a potential effective material to treat FP as well as the glass medium.

Journal Articles

Pyroreprocessing development for next generation energy; Reducing high-level radioactive waste volume

Amamoto, Ippei

Journal of MMIJ, 127(1), p.1 - 7, 2011/01

The pyroprocess as a non-aqueous reprocessing, is oriented as a complementary concept for the Fact Project. The pyroprocess possesses some inherent problems that have yet to be solved. The purification and recycling of the spent electrolyte as a regenerated medium by removing its fission products (FP) must be further investigated to reduce the volume of high-level radioactive waste (HLW). Some FP elements dissolved in the medium are apt to remain in the spent electrolyte after recovering actinoid elements. To remove such FP, the zeolite sorption is applied as it is considered the most suitable method, but its concept should be modified in order to reduce the generating waste volume. As one of the solutions, the electrolyte recycle process by phosphates is being developed. In this paper, the author has discussed the pyroprocess development, highlighting the spent electrolyte treatment from the viewpoint of economical and environmental load reduction.

Journal Articles

Development of iron phosphate glass with Cs sorption function; Study on suitable chemical composition for glass filter and its sorption mechanism

Mitamura, Naoki*; Tsuzuki, Tatsuya*; Amamoto, Ippei

Nippon Genshiryoku Gakkai Wabun Rombunshi, 9(4), p.396 - 404, 2010/12

Iron phosphate glass could be used to immobilize the high-level radioactive waste (HLW) and has the possibility to function as a Cs sorpant. However, the glass must endure high temperature from about 350$$^{circ}$$C, the melting point of LiCl-KCl electrolyte, to 600$$^{circ}$$C, the operational maximum temperature. In this study, we have successfully developed the iron phosphate glasses functioning as Cs sorpant, possessing heat resistance, etc.. To prevent the glass softening at temperature around 600$$^{circ}$$C, alkali metal oxides, alkaline-earth metal oxides, alumina and/or titania were added into the Fe$$_{2}$$O$$_{3}$$-P$$_{2}$$O$$_{5}$$ glass. Through soak experiments of the glasses in molten salt($$^{3}$$LiCl-KCl)containing CsCl, it was found that those glasses immobilize Cs by reacting with CsCl and formed crystal phase of CsFeCl$$_{3}$$ and/or Cs$$_{3}$$FeCl$$_{3}$$. This Cs sorption function is peculiar to the developed iron phosphate glasses.

Journal Articles

Removal of fission products in the spent electrolyte using iron phosphate glass as a sorbent

Amamoto, Ippei; Mitamura, Naoki*; Tsuzuki, Tatsuya*; Takasaki, Yasushi*; Shibayama, Atsushi*; Yano, Tetsuji*; Nakada, Masami; Okamoto, Yoshihiro

Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.503 - 508, 2010/10

The main objective of this development is to recycle the purified eutectic medium of the pyroreprocessing, delaying its disposal for as long as possible. We have introduced the simple filtration method to remove the rare earth element (REE) particles which were formed due to the conversion of REE chlorides to phosphates. Here, the iron phosphate glass is used as a filtration medium for the removal of FP particles. However, some soluble FP such as compounds of alkali-metals, alkaline-earth metals, etc. still remain in the eutectic medium. This time around, on an experimental basis, the iron phosphate glass has been used as a sorbent instead, to remove the soluble FP. We have obtained some positive results and have intention to incorporate it into the spent electrolyte recycle process as a part of the FP separation and immobilization system.

Journal Articles

Precipitation behaviors of fission products by phosphate conversion in LiCl-KCl medium

Amamoto, Ippei; Kofuji, Hirohide; Myochin, Munetaka; Takasaki, Yasushi*; Yano, Tetsuji*; Terai, Takayuki*

Nuclear Technology, 171(3), p.316 - 324, 2010/09

 Times Cited Count:10 Percentile:38.22(Nuclear Science & Technology)

The separation technique by phosphate conversion of FP from NaCl-KCl or NaCl-2CsCl as the medium of the spent electrolyte of pyroprocessing is being developed at RIAR in Russia. To ascertain the technical feasibility of applying this RIAR's method for recycling of spent electrolyte which composed of FP such as AL, ALE, and REE and 3LiCl-2KCl as the medium, preliminary study was undertaken at JAEA. This study occupies an auxiliary role which is forwarded as a part of FaCT Project of Japan. As a first approach, the thermodynamic analysis to understand the behaviours of FP in the electrolyte was carried out after literature research and acquisition of required thermodynamic properties. Preliminary experiment was then undertaken to observe the conversion behaviours of chlorides to phosphate. In this paper, these results are shown and are evaluated to discern the feasibility of the phosphate conversion method.

Journal Articles

Separation of lanthanoid phoshates from the spent electrolyte of pyroprocessing

Amamoto, Ippei; Kofuji, Hirohide; Myochin, Munetaka; Tsuzuki, Tatsuya*; Takasaki, Yasushi*; Yano, Tetsuji*; Terai, Takayuki*

Proceedings of 12th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '09/DECOM '09) (CD-ROM), 9 Pages, 2009/10

This study is carried out to make the pyroprocessing hold a competitive advantage. As one of the measures is to reduce the volume of HLW, the phosphate conversion method is applied for removal of FP from the spent electrolyte in this paper. Though the removing target elements in the electrolyte are alkali metals, alkaline earth metals and lanthanoid elements, only lanthanoid elements and lithium form the insoluble phosphates by reaction with Li$$_{3}$$PO$$_{4}$$. Therefore, as the first step, the precipitation experiment was carried out to observe the behaviours of elements which form the insoluble precipitates. Then the filtration was experimented to remove precipitates in the spent electrolyte using Fe$$_{2}$$O$$_{3}$$-P$$_{2}$$O$$_{5}$$ glass system as a filtlation medium which is compatible material with the glassification. The result of separation of precipitates by filtration was effective and attained almost 100$$%$$.

Journal Articles

Phosphate conversion behaviors of FP chlorides with spent electrolyte recycling

Kofuji, Hirohide; Amamoto, Ippei; Sasaki, Kazuya*; Yasumoto, Masaru*; Takasaki, Yasushi*; Myochin, Munetaka; Terai, Takayuki*

Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 77(8), p.597 - 600, 2009/08

 Times Cited Count:0 Percentile:100(Electrochemistry)

The process flow of the phosphate conversion technique has been developed for the reduction of high-level radioactive waste (HLW) generated from the metal-electrorefining process. In this study, the results of thermodynamic calculations for the phosphate conversion reactions were examined by the basic experiments. The chlorides of rare earth elements (REE) turned out to be converted into phosphates easily. Furthermore, as the additive for the phosphate conversion reaction, high temperature behavior of lithium phosphate was evaluated to elucidate the thermodynamic property.

Journal Articles

Phosphates behaviours in conversion of FP chlorides

Amamoto, Ippei; Kofuji, Hirohide; Myochin, Munetaka; Takasaki, Yasushi*; Terai, Takayuki*

Journal of Nuclear Materials, 389(1), p.142 - 148, 2009/05

 Times Cited Count:13 Percentile:30.95(Materials Science, Multidisciplinary)

The spent electrolyte of the pyroprocessing by metal electrorefining method should be considered for recycling after removal of FP, such as AL (alkali metals), ALE (alkaline earth metals), and/or REE (rare-earth elements), to reduce the volume of HLW. Authors have been carrying out theoretical analysis and experiment showing the behaviours of phosphate precipitates so as to estimate the feasibility of the phosphate conversion method. From hitherto results, it was found that AL except Li, and ALE are unlikely formed phosphate precipitates. However, their conversion behaviours including REE were compatible with former presented theoretical analysis; in the case of lanthanum precipitate as one of REE, submicron-size particles could be observed while that of Li$$_{3}$$PO$$_{4}$$ was larger; under different conversion temperatures, the precipitates were apt to grow larger at higher temperature; etc..

Journal Articles

Evaluation of phosphate thermodynamic properties for spent electrolyte recycle

Kofuji, Hirohide; Amamoto, Ippei; Yasumoto, Masaru*; Sasaki, Kazuya*; Myochin, Munetaka; Terai, Takayuki*

Journal of Nuclear Materials, 389(1), p.173 - 178, 2009/05

 Times Cited Count:3 Percentile:73.29(Materials Science, Multidisciplinary)

Adaptation of the phosphate conversion technique was undertaken and evaluated for application to the recycle process of the spent electrolyte generated from metal electrorefining process which is a kind of pyrochemical reprocessing technologies. The conceptual flow sheet has been discussed based on the thermodynamic properties of constituent. However few data have been published relating to the phosphate, therefore, the thermodynamic data were attempted to be obtained by the calorimetry and vapor pressure measurements. The measurements have been started with pure substance such as lithium phosphate. Through the measurements of HTMS and TG-DTA, it was clarified that decomposition or phase transition of Li$$_{3}$$PO$$_{4}$$ occurred at specific temperatures below the melting point of Li$$_{3}$$PO$$_{4}$$. To avoid the influence of fragment substances which have high vapour pressures, improved method of the HTMS measurement was examined.

Journal Articles

Phosphate glass

Amamoto, Ippei

Garasu No Kako Gijutsu To Seihin Oyo, p.10 - 20, 2009/01

no abstracts in English

Journal Articles

Development of a pyrochemical process in molten salts for treating radioactive waste from nuclear fuel cycle facilities

Fujita, Reiko*; Nakamura, Hitoshi*; Mizuguchi, Koji*; Utsunomiya, Kazuhiro*; Amamoto, Ippei

Proceedings of 2008 Joint Symposium on Molten Salts (USB Flash Drive), p.886 - 891, 2008/10

Pyrochemical treatment in molten salts is a promising process for decontamination of radioactive wastes without producing large amounts of secondary waste. In this report, the fundamental experiment was carried out to treat the wastes which had complicated shapes such as Magnoxend corps, metallic waste contaminated by uranium, spent chemical trap fillers and spent Zircaloy channel boxs from BWR and acquired good results.

Journal Articles

Use of thermodynamic simulation for preliminary study on electrolyte recycle process by the phosphate conversion technique

Amamoto, Ippei; Kofuji, Hirohide; Myochin, Munetaka; Terai, Takayuki*

Shimyureshon, 27(3), p.189 - 197, 2008/09

Some specific FPs are apt to remain in the medium (electrolyte) used in pyroprocessing even after recovery of uranium and transuranic elements. It is desirable to have the spent electrolyte purified for recycling which in turn, could lead to the reduction of HLW. This study is carried out to evaluate the feasibility of the electrolyte recycle process by the phosphates conversion technique. The evaluation was undertaken mainly by thermodynamic simulation which was especially highlighted the conversion effect at the Spent Electrolyte Generation Step. The obtained computational value and a conceptual idea for recovery of precipitates by this simulation were then reflected to establish the preliminary conceptual flow diagram which would facilitate the next discussion and experiment for the realization of this process.

108 (Records 1-20 displayed on this page)