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Journal Articles

Design and performance of high-pressure PLANET beamline at pulsed neutron source at J-PARC

Hattori, Takanori; Sano, Asami; Arima, Hiroshi*; Komatsu, Kazuki*; Yamada, Akihiro*; Inamura, Yasuhiro; Nakatani, Takeshi; Seto, Yusuke*; Nagai, Takaya*; Utsumi, Wataru; et al.

Nuclear Instruments and Methods in Physics Research A, 780, p.55 - 67, 2015/04

 Times Cited Count:52 Percentile:98.93(Instruments & Instrumentation)

PLANET is a time-of-flight (ToF) neutron beamline dedicated to high-pressure and high-temperature experiments. The large six-axis multi-anvil high-pressure press designed for ToF neutron diffraction experiments enables routine data collection at high pressures and high temperatures up to 10 GPa and 2000 K, respectively. To obtain clean data, the beamline is equipped with the incident slits and receiving collimators to eliminate parasitic scattering from the high-pressure cell assembly. The high performance of the diffractometer for the resolution ($$Delta$$ $$d$$/$$d$$ $$sim$$ 0.6%) and the accessible $$d$$-spacing range (0.2-8.4 ${AA}$) together with low-parasitic scattering characteristics enables precise structure determination of crystals and liquids under high pressure and temperature conditions.

Journal Articles

Metal adsorption of carboxymethyl cellulose/carboxymethyl chitosan blend hydrogels prepared by $$gamma$$ irradiation

Hiroki, Akihiro; Tran, H. T.*; Nagasawa, Naotsugu; Yagi, Toshiaki*; Tamada, Masao

Radiation Physics and Chemistry, 78(12), p.1076 - 1080, 2009/12

 Times Cited Count:43 Percentile:94.96(Chemistry, Physical)

To investigate an adsorption of Pb and Au ions, blend hydrogels based on the carboxymethyl cellulose (CMC) and carboxymethyl chitosan (CMCts) were prepared by $$gamma$$-irradiation of a high concentrated CMC/CMCts aqueous solution. The blend hydrogels showed a degree of swelling in the range of 30 to about 550 g -water/g -dried gel. The gel fraction of the blend hydrogels increased sharply up to 30 kGy and reached a constant value in the range of 100-200 kGy. The gel fraction of the blend hydrogel decreased with increasing the ratio of CMCts. Nitrogen content in the hydrogels was determined by means of elemental analysis. The nitrogen content in the obtained hydrogels was proportional to the ratio of CMCts in the mixture, which was almost equal with theoretical ones. This is indicated that the obtained hydrogels were constructed at the initial ratio of CMC/CMCts. The rate of the metal ions adsorbed to the blend hydrogels increased with increasing the composition of CMCts. In the case of Pb, the CMC/CMCts blend gels showed the enhancement of the adsorption rate in the range of 55% to 80%. Although the adsorption rate of Au ions was only 10% at CMC/CMCts 100/0, it reached at 60% at 75/25, and then increased up to about 90% at 0/100. The obtained blend hydrogels had high adsorption performance which was controlled by adjusting the composition of CMC/CMCts.

Journal Articles

Experimental durability studies of electrolysis cell materials for a water detritiation system

Iwai, Yasunori; Hiroki, Akihiro; Yagi, Toshiaki*; Tamada, Masao; Yamanishi, Toshihiko

Fusion Engineering and Design, 83(10-12), p.1410 - 1413, 2008/12

 Times Cited Count:5 Percentile:37.69(Nuclear Science & Technology)

The radiation durability of the solid-polymer-electrolyte (SPE) water electrolyzer composed of the Water Detritiation System (WDS) was investigated. A series of $$gamma$$-ray and electron beam irradiation tests of Nafion N117 ion exchange membrane, a key polymer in a SPE electrolyzer, beyond ITER-WDS requirement (530kGy) indicated Nafion N117 has enough radiation durability up to 1600 kGy from the view points of mechanical strength and ion exchange capacity. To keep electrolysis function of a SPE cell up to 530 kGy, we suggest replacing Teflon with polyimide. A series of $$gamma$$-ray irradiation test of Kapton polyimide observed no serious damage in strength up to 1500 kGy. Concerning rubber material for O-ring seal, we observed that soaking VITON rubber keeps the constant value of tensile strength up to 1500 kGy. Moreover organic elution was not observed from a soak of VITON. From the viewpoint of stable strength and organic elution, VITON is a first candidate for rubber material.

Journal Articles

Radiation-induced crosslinking and mechanical properties of blends of poly(lactic acid) and poly(butylene terephthalate-${it co}$-adipate)

Sarath Kumara, P. H.*; Nagasawa, Naotsugu; Yagi, Toshiaki; Tamada, Masao

Journal of Applied Polymer Science, 109(5), p.3321 - 3328, 2008/09

 Times Cited Count:17 Percentile:50.74(Polymer Science)

Blends of poly(L-lactic acid) (PLLA) and poly(butylene terephthalate-${it co}$-adipate) (PBTA) were prepared at ratios of 50:50, 60:40, and 80:20 by melt blending in a Laboplastomill. Improved mechanical properties were observed in PLLA when it was blended with PBTA, a biodegradable flexible polymer. Irradiation of these blends with an electron beam (EB) in the presence of triallyl isocyanurate (TAIC), a polyfunctional monomer, did not cause any significant improvement in the mechanical properties, although the gel fraction increased with the TAIC level and dose level. Irradiation of the blends without TAIC led to a reduction in the elongation at break but did not show asignificant effect on the tensile strength. The elongation at break of PBTA was unaffected by EB radiation in the absence of TAIC.

Journal Articles

Solid-polymer-electrolyte tritiated water electrolyzer for water detritiation system

Iwai, Yasunori; Yamanishi, Toshihiko; Hiroki, Akihiro; Yagi, Toshiaki*; Tamada, Masao

Fusion Science and Technology, 54(2), p.458 - 461, 2008/08

 Times Cited Count:4 Percentile:31.93(Nuclear Science & Technology)

A solid-polymer-electrolyte (SPE) water electrolyzer for high-level tritiated water was designed for the Water Detritiation System (WDS). Polymeric materials were selected from a main viewpoint of radiation durability to keep their functions beyond ITER-WDS requirement (530 kGy). Our selection was Pt + Ir applied Nafion N117 ion exchange membrane, VITON O-ring seal and polyimide insulator. A g-ray irradiation test of the SPE cell demonstrated the durability of the cell against 530 kGy. The detritiation of the polymeric materials is a critical problem for the maintenance or for the disposal of the electrolyzer. As for the Nafion membrane, most of tritiated water in the membrane was rapidly removed by such as vacuum dehydration. It was difficult, by contrast, to remove bound tritiated water in the membrane. An effective method to remove tritiated water in the bound water is to promote an isotope exchange.

Journal Articles

Preparation and properties of CMC gel

Takigami, Machiko*; Amada, Haruyo*; Nagasawa, Naotsugu; Yagi, Toshiaki; Kasahara, Takamitsu*; Takigami, Shoji*; Tamada, Masao

Transactions of the Materials Research Society of Japan, 32(3), p.713 - 716, 2007/09

Carboxymethylcellulose (CMC) gel was formed by addition of acid to CMC (CMC-acid gel). Gel fraction (weight of insoluble part/initial CMC weight) was calculated after removing uncrosslinked CMC by immersing the CMC-acid gel in water. It increased with acid concentration. Mechanism of CMC-acid gel formation was elucidated by aggregation of CMC molecules as the result of replacement of sodium in carboxyl group with hydrogen. Gels could be prepared by three different procedures; (1) mixing CMC and acid, (2) immersion of CMC or $$gamma$$-irradiated CMC pastes in acid, and (3) $$gamma$$-irradiation of CMC-acid gel. Gels with different elasticity and hardness were prepared changing degree of substitution of CMC, molar mass of CMC, species of acid, concentrations of acid and CMC, and application of $$gamma$$-irradiation.

Journal Articles

Metal adsorption of chitin / chitosan derivatives hydrogels crosslinked with irradiation

Nagasawa, Naotsugu; Wasikiewicz, J. M.*; Seko, Noriaki; Yagi, Toshiaki; Zhao, L.*; Mitomo, Hiroshi*; Yoshii, Fumio; Tamada, Masao

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 52, 2007/02

Radiation crosslinking of chitin / chitosan derivatives such as carboxymethylchitin (CMCt) and carboxymethylchitosan (CMCts) has been investigated. CMCt and CMCts of 40% concentration were irradiated by electron beams. The maximum gel fraction of those CMCht and CMChts reached 72% (75kGy) and 50% (100kGy) respectively. These gels absorpted water of 8.3g for CMCt and 21.2g for CMCts per 1 g of the dried gel. The absorption ability of various metal ions with these gels has been investigated. The highest adsorption of scandium and gold has been obtained for CMCt and CMCts gels, respectively.

Journal Articles

Modification of poly(lactic acid) by radiation-induced crosslinking

Nagasawa, Naotsugu; Kaneda, Ayako*; Matsuzaki, Tomoaki*; Kanazawa, Shinichi*; Yagi, Toshiaki; Tran, M. Q.*; Mitomo, Hiroshi*; Yoshii, Fumio; Tamada, Masao; Quynh, T. M.*

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 53, 2007/02

Poly(L-lactic acid), PLA was irradiated using electron beams (EB) in the presence of polyfunctional monomers (PFM) as crosslinking agent. Among the PFMs, triallyl isocyanurate (TAIC) at 3% concentration was found to be the most effective for crosslinking of PLA by irradiation technique. The crosslinked PLA obtained has heat resistance higher than 200$$^{circ}$$C. From this fact, the crosslinked PLA is applied on heat-shrinkable tube, cup and plate. The shrinkable tube has several advantages such as high heat resistance and transparency. It is therefore proven that crosslinking technology is beneficial to expanding the application of PLA.

Journal Articles

Enhancement of plant growth activity of irradiated alginate

Nagasawa, Naotsugu; Luan, L. Q.*; Yagi, Toshiaki; Yoshii, Fumio; Kume, Tamikazu; Nakanishi, Tomoko*; Tamada, Masao

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 55, 2007/02

The sodium alginate was irradiated by $$gamma$$-ray, and plant growth activity test and structural change of the product were studied. It was found that the concentration of 100 mg/L of alginate irradiated at 75 kGy in 4 % aqueous solution was the highest for plant growth. Separation of the degraded product was performed using ultrafiltration membranes and found that fraction with molecular weight in the range of 1-3 kDa (6-15 units) not only showed a remarkable effect on the plant growth, but also increased the activity of plant enzymes; ${it alcohol dehydrogenase, phenylalanine ammonia-lyase}$. This fraction was stronger than one of the enzymatic degradation product. This differences proposed formation of carbonyl and carboxyl groups along with the main-chain scission.

Journal Articles

Cooperative research on radiation processing of natural polysaccharides between VAEC and JAEA

Hiroki, Akihiro; Nagasawa, Naotsugu; Yagi, Toshiaki; Kume, Tamikazu; Yoshii, Fumio; Tamada, Masao

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 56, 2007/02

Cooperative research between Vietnam Atomic Energy Commission (VAEC) and JAEA has been performed over a period of six years. In the cooperative research, natural polysaccharides such as alginate, chitin, and chitosan were irradiated by $$gamma$$-ray to produce various functional materials. It was found that the alginate and the chitosan degraded with $$gamma$$-irradiation were effective as a growth promoter for rice and carrot and an anti-bacterial agent, respectively. On the other hand, the hydrogels obtained by $$gamma$$-irradiating carboxymethylchitosan aqueous solution in paste-like state showed a high adsorption capacity for Cu (II) ions as well as the anti-bacterial activity.

Journal Articles

Radiation effects on PTFE moulding powder

Yagi, Toshiaki; Tamada, Masao; Udagawa, Akira*

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 57, 2007/02

Change of mecahnical properties of polytetrafluoroethylene(PTFE) were examined by means of $$gamma$$ irradiation of the moulding powder prior to compression moulding. Share strength and elongation of PTFE incresed 4 times with incresing of the radiation dose, whereas tensile strength maintained inrinsic value. Gas transmission rate of nitrogen and oxygen were also considerably controlled to lower value. These results suggest that the irradiation effect on PTFE mouling powder are useful for industrial applications.

JAEA Reports

Continuous running test of radiation resistance motor driving equipment under high gamma ray irradiation

Obara, Kenjiro; Kakudate, Satoshi; Yagi, Toshiaki; Morishita, Norio; Shibanuma, Kiyoshi

JAEA-Technology 2006-023, 38 Pages, 2006/03


The components in the vacuum vessel of ITER (International Thermonuclear Experimental Reactor), e.g. blanket and divertor, are replaced using the dedicated remote handling systems. The environment conditions inside the vacuum vessel during the operation are temperature of 50$$^{circ}$$C, gamma ray radiation and air or inert gas atmosphere at 1 atm. ; therefore multiple elements are required as durability of the remote handling systems. In addition, the remote handling system it is desired to be able to operate over a long time. The radiation resistance motor driving equipment, which comprises parts with different radiation resistance levels, was designed simulating mechanisms of the ITER remote handling systems. The equipment being the servomotor, turns the weight (dummy load) of 8 kgf and controls, and continuous running test under high gamma ray irradiation was started from March, 2000. Irradiation conditions on the test were the dose rate of 3.6 kGy/h, the target accumulation dose of 30 MGy at the minimum. The irradiation test was performed two stages which was divided by overhaul of the equipment. The achieved accumulation dose and running time in these stages were approximately 47.6 MGy/13,200 hours and 23.9 MGy/6,640 hours, respectively. As a result, it has been confirmed that sufficient radiation resistance of the equipment, which is required from the latest dose rate of 0.5 kGy/h inside the vacuum vessel was achieved. In this report, we describe design conditions of the equipment and the results of the 1st and 2nd irradiation tests and the overhaul after the 1st irradiation test.

Journal Articles

Distinctive radiation durability of an ion exchange membrane in the SPE water electrolyzer for the ITER water detritiation system

Iwai, Yasunori; Yamanishi, Toshihiko; Isobe, Kanetsugu; Nishi, Masataka; Yagi, Toshiaki; Tamada, Masao

Fusion Engineering and Design, 81(1-7), p.815 - 820, 2006/02

 Times Cited Count:14 Percentile:71.07(Nuclear Science & Technology)

Solid-polymer-electrolyte (SPE) water electrolysis is attractive in electrolytic process of water detritiation system (WDS) in fusion reactors because it can electrolyze liquid waste directly, but radioactive durability of its ion exchange membrane is a key point. Radioactive durability of Nafion, a typical commercial ion exchange membrane, was experimentally investigated using Co-60 irradiation facility and electron beam irradiation facility at Takasaki Radiation Chemistry Research Establishment of JAERI. Nafion is composed of PTFE (Polytetrafluoroethylene) main chain. However the degradation of its mechanical strength by irradiation was significantly distinguished from that of PTFE and no serious damage was observed for its ion exchange capacity up to 530 kGy, the requirement of ITER. Atmospheric effects such as soaking and oxygen on degrading behaviors were discussed from the viewpoint of radical reaction mechanism. Dependencies of operating temperature and radioactive source are also demonstrated in detail.

Journal Articles

Durability of irradiated polymers in solid-polymer-electrolyte water electrolyzer

Iwai, Yasunori; Yamanishi, Toshihiko; Nishi, Masataka; Yagi, Toshiaki; Tamada, Masao

Journal of Nuclear Science and Technology, 42(7), p.636 - 642, 2005/07

 Times Cited Count:18 Percentile:77(Nuclear Science & Technology)

Radioactive durability of organic polymers in solid-polymer-electrolyte water electrolyzer was investigated by $$gamma$$-ray irradiation. Serious deteriorations for tensile strength and ion exchange capacity of ion exchange membrane (Nafion) were not observed up to 850 kGy. No serious damage was also observed for the gasket materials (Aflas) up to 500 kGy. PFA and FEP, insulator materials, lost their tensile strength at 300 kGy or less. As the result, it is concluded that the electrolyzer could be used up to around 500 kGy in the case where PFA and FEP are replaced by the polyimide resin whose durability is well demonstrated. Two degrading mechanisms were supposed. One is direct degradation by energy of radial rays. The other is that by the attack of radicals. It was demonstrated that the effect of radicals on the membrane was not dominant. The quantity of dissolved fluorine in water was found to correlate with the tensile strength and ion exchange capacity. Hence, it is possible to evaluate the degradation of the membrane by monitoring the quantity of dissolved fluorine.

Journal Articles

Application of poly(lactic acid) modified by radiation crosslinking

Nagasawa, Naotsugu; Kaneda, Ayako*; Kanazawa, Shinichi*; Yagi, Toshiaki; Mitomo, Hiroshi*; Yoshii, Fumio; Tamada, Masao

Nuclear Instruments and Methods in Physics Research B, 236(1-4), p.611 - 616, 2005/07

 Times Cited Count:74 Percentile:98.03(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Radiation crosslinking of carboxymethyl starch

Nagasawa, Naotsugu; Yagi, Toshiaki; Kume, Tamikazu; Yoshii, Fumio

Carbohydrate Polymers, 58(2), p.109 - 113, 2004/11

 Times Cited Count:87 Percentile:93.92(Chemistry, Applied)

A new biodegradable starch derivative hydrogel, carboxymethyl starch (CMS) hydrogel, was synthesized by irradiation in high concentrated solution (in the so-called paste-like condition). The effect of the solution concentration on the crosslinking of CMS, the properties of formed hydrogel and the biodegradability were investigated. The crosslinking of CMS was induced by irradiation at concentration range from 20 to 50 %. 1 g of the dry gel formed from the solution at concentration of 40 % crosslinked at dose of 2 kGy was able to absorb about 500 and 26 g of distilled water and 0.9 % NaCl, respectively. Biodegradation of crosslinked CMS (irradiated in 50 % solution at a dose of 5 kGy) by controlled composting was about 40 % after 2 weeks which was faster than standard cellulose powder. The contribution of crosslinking in CMS was elucidated from crosslinking behaviors of carboxymethyl amylopectin (CMAP) and carboxymethyl amylose (CMA). The crosslinked CMAP (irradiated at a concentration range from 10 to 50 %) reveal higher gel fraction and water-uptake than that of CMA. The amylopectin region in CMS is predominantly responsible for crosslinking of CMS.

Journal Articles

Modification of enviromentally-friendly polymer by radiation and its applications in agriculture and welfare fields

Yagi, Toshiaki

Dai-14-Kai Hoshasen Riyo Gijutsu Semina; Hirogaru Hoshasen No Sangyo Riyo Koen Tekisuto, p.67 - 72, 2004/10

no abstracts in English

Journal Articles

Development of novel plastics by radiation technology

Nagasawa, Naotsugu; Yagi, Toshiaki

Science & Technology Journal, 13(10), p.20 - 21, 2004/10

no abstracts in English

Journal Articles

Radiation-modified PTFE as the 21st century material; Development of high function and extreme tenacity for PTFE

Udagawa, Akira*; Ikeda, Shigetoshi*; Yagi, Toshiaki

Hoshasen To Sangyo, (103), p.54 - 58, 2004/09

no abstracts in English

JAEA Reports

Development of colored alumilite dosimeter

Obara, Kenjiro; Yagi, Toshiaki; Yokoo, Noriko*; Shibanuma, Kiyoshi

JAERI-Tech 2003-035, 107 Pages, 2003/03


no abstracts in English

96 (Records 1-20 displayed on this page)