Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 226

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Studies on processes for recovering uranium from sediment wastes

Ohashi, Yusuke; Ikeda, Yasuhisa*

Journal of Radioanalytical and Nuclear Chemistry, 321(2), p.683 - 691, 2019/08

Sediment waste generated from the waste solution of uranium handling facilities contains uranium and iron. In this study, we examined methods to selectively separate uranium from the waste without using nitric acid. Uranium dissolved in 0.5 $$ sim$$ 2.5M sulfuric acid, 1M hydrochloric acid, and 5M perchloric acid was selectively precipitated by adding oxalic acid. In addition, when oxalic acid and NCP are added together in 2.5M sulfuric acid, it seems that new insoluble uranium compounds are formed. Consequently, precipitation ratios of uranium was improved. Uranium was selectively precipitated from the sulfuric acid solution containing Fe and Al, and the precipitation ratio of uranium became 99%.

Journal Articles

Low $$^{137}$$Cs retention capability of organic layers in Japanese forest ecosystems affected by the Fukushima nuclear accident

Koarashi, Jun; Atarashi-Andoh, Mariko

Journal of Radioanalytical and Nuclear Chemistry, 320(1), p.179 - 191, 2019/04

 Times Cited Count:1 Percentile:8.43(Chemistry, Analytical)

To quantify the $$^{137}$$Cs retention behavior in forest-floor organic layers in relation to the litter dynamics, litter samples were collected at five forest sites in Fukushima in 2011 and 2015, and separated into eight fractions with different precursor species and degrees of degradation; afterward, $$^{137}$$Cs inventory was determined in each litter fraction. The ecological half-lives of $$^{137}$$Cs in the litter fractions were estimated to be from 0.7 to 4.4 years and found to depend not on the sampling site but rather on the precursor species of the litter materials. Broadleaf- and pine-needle-originated litter fractions exhibited shorter ecological half-lives of $$^{137}$$Cs, while those of cedar-originated and finely fragmented litter fractions were longer. The results suggested that the organic layers in Japanese forest ecosystems have a low $$^{137}$$Cs retention capability, although it differs depending on the forest type.

Journal Articles

Secondary radiocesium contamination of agricultural products by resuspended matter

Nihei, Naoto*; Yoshimura, Kazuya; Okumura, Taiga*; Tanoi, Keitaro*; Iijima, Kazuki; Kogure, Toshihiro*; Nakanishi, Tomoko*

Journal of Radioanalytical and Nuclear Chemistry, 318(1), p.341 - 346, 2018/10

 Percentile:100(Chemistry, Analytical)

Journal Articles

Correlation between Am(III)/Eu(III) selectivity and covalency in metal-chalcogen bonds using density functional calculations

Kaneko, Masashi; Watanabe, Masayuki

Journal of Radioanalytical and Nuclear Chemistry, 316(3), p.1129 - 1137, 2018/06

 Times Cited Count:4 Percentile:4.12(Chemistry, Analytical)

We applied density functional theory calculations to Am(III) and Eu(III) complexes with chalcogen-donor ligands of the formula N(EPMe$$_{2}$$)$$_{2}$$$$^{-}$$ (E = O, S, Se, Te). We calculated the equilibrium structures and relative stabilities of the complexes in the complexation reaction. The results indicated that the tendency of the relative stability is O $$ll$$ S $$sim$$ Se $$sim$$ Te, which is consistent with the trend of soft acid classification. Molecular orbital overlap population analysis suggested that this tendency can be correlated with the bonding type in the covalent interaction between the f-orbitals of the metal atom and the chalcogen-donor atoms.

Journal Articles

Am, Cm recovery from genuine HLLW by extraction chromatography

Watanabe, So; Sano, Yuichi; Kofuji, Hirohide; Takeuchi, Masayuki; Shibata, Atsuhiro; Nomura, Kazunori

Journal of Radioanalytical and Nuclear Chemistry, 316(3), p.1113 - 1117, 2018/06

 Percentile:100(Chemistry, Analytical)

Journal Articles

Radiation-induced degradation of aqueous 2-chlorophenol assisted by zeolites

Kumagai, Yuta; Kimura, Atsushi*; Taguchi, Mitsumasa*; Watanabe, Masayuki

Journal of Radioanalytical and Nuclear Chemistry, 316(1), p.341 - 348, 2018/04

 Percentile:100(Chemistry, Analytical)

We studied effect of adsorption and condensation by zeolites on radiation-induced degradation of aqueous 2-chlorophenol (2-ClPh). This study aims to demonstrate that the solid-phase extraction using zeolites has potential advantage in treatments of aqueous organic pollutants. Among three zeolites examined in this study, a mordenite type zeolite (HMOR) that has a high Si to Al ratio (127 $$pm$$ 3) exhibited preferable performance as the matrix for the 2-ClPh degradation. HMOR adsorbed far more 2-ClPh than the other zeolites, which have lower Si/Al ratios. The irradiation of HMOR induced degradation of adsorbed 2-ClPh into Cl$$^{-}$$ and organic by-products. We found a significant increase in Cl$$^{-}$$ production by HMOR. The yield of Cl$$^{-}$$ production in the presence of HMOR was as high as the yield in aqueous solution of 2-ClPh at a concentration 10 times higher. The increased Cl$$^{-}$$ production indicates that the high concentration of adsorbed 2-ClPh led to effective use of the adsorbed energy of HMOR.

Journal Articles

Overall approaches and experiences of first-time participants in the Nuclear Forensics International Technical Working Group's Fourth Collaborative Material Exercise (CMX-4)

Ho, D. M. L.*; Nelwamondo, A. N.*; Okubo, Ayako; Rameb$"a$ck, H.*; Song, K.*; Han, S.-H.*; Hancke, J. J.*; Holmgren, S.*; Jonsson. S.*; Kataoka, Osamu; et al.

Journal of Radioanalytical and Nuclear Chemistry, 315(2), p.353 - 363, 2018/02

 Percentile:100(Chemistry, Analytical)

The Fourth Collaborative Material Exercise (CMX-4) of the Nuclear Forensics International Technical Working Group (ITWG) registered the largest participation for this exercise in nuclear forensics, with seven of the 17 laboratories participating for the first time. In this paper, participants from five of the first-time laboratories shared their individual experience in this exercise, from preparation to analysis of samples. The exercise proved to be highly useful for testing procedures, repurposing established methods, exercising skills, and improving the understanding of nuclear forensic signatures and their interpretation trough the post-exercise review meeting.

Journal Articles

The Application of radiochronometry during the 4th collaborative materials exercise of the nuclear forensics international technical working group (ITWG)

Kristo, M. J.*; Williams, R.*; Gaffney, A. M.*; Kayzar-Boggs, T. M.*; Schorzman, K. C.*; Lagerkvist, P.*; Vesterlund, A.*; Rameb$"a$ck, H.*; Nelwamondo, A. N.*; Kotze, D.*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 315(2), p.425 - 434, 2018/02

 Times Cited Count:1 Percentile:38.14(Chemistry, Analytical)

In a recent international exercise, 10 international nuclear forensics laboratories successfully performed radiochronometry on three low enriched uranium oxide samples, providing 12 analytical results using three different parent-daughter pairs serving as independent chronometers. The vast majority of the results were consistent with one another and consistent with the known processing history of the materials. In general, for these particular samples, mass spectrometry gave more accurate and more precise analytical results than decay counting measurements. In addition, the concordance of the $$^{235}$$U-$$^{231}$$Pa and $$^{234}$$U-$$^{230}$$Th chronometers confirmed the validity of the age dating assumptions, increasing confidence in the resulting conclusions.

Journal Articles

Production of iodine radionuclides using $$^{7}$$Li ion beams

Nishinaka, Ichiro*; Yokoyama, Akihiko*; Washiyama, Koshin*; Makii, Hiroyuki; Hashimoto, Kazuyuki*

Journal of Radioanalytical and Nuclear Chemistry, 314(3), p.1947 - 1965, 2017/12

 Times Cited Count:1 Percentile:64.68(Chemistry, Analytical)

Production cross sections of iodine, tellurium and antimony radionuclides in the 24-59 MeV $$^{7}$$Li + $$^{nat}$$Sn reaction have been measured by the conventional stacked foil technique with $$gamma$$-ray spectrometry. Excitation functions of the production cross sections were compared with a statistical model calculation. The contributions of complete and incomplete fusion in the production of observed radionuclides are discussed from the view points of production routes in the nuclide chart and decays for iodine, tellurium and antimony nuclides. The integral yields of $$^{123,124,125,126}$$I were deduced from the calculated excitation functions in the $$^{7}$$Li induced reactions on Sn isotopes in view of the production of medically important $$^{123,124}$$I. The results are discussed by comparing with literature values in the other reactions.

Journal Articles

Development of determination method of $$^{93}$$Mo content in metal waste generated at the Japan Power Demonstration Reactor

Shimada, Asako; Omori, Hiroyuki*; Kameo, Yutaka

Journal of Radioanalytical and Nuclear Chemistry, 314(2), p.1361 - 1365, 2017/11

 Percentile:100(Chemistry, Analytical)

A separation method of Mo from Nb, Zr, and the matrix elements of rubble waste was modified to determine the content of $$^{93}$$Mo in metal waste. A separation scheme to treat 1 g of metal waste was established by optimizing the amount of ascorbic acid, the rinsing solution, and repeating of the procedure. A thin-layer source was prepared using direct drop deposition and evaporation to measure $$^{93}$$Mo content. Finally, $$^{93}$$Mo content in the metal waste generated at the Japan Power Demonstration Reactor was analyzed using the developed method.

Journal Articles

Sources of $$^{137}$$Cs fluvial export from a forest catchment evaluated by stable carbon and nitrogen isotopic characterization of organic matter

Muto, Kotomi; Atarashi-Andoh, Mariko; Koarashi, Jun; Takeuchi, Erina; Nishimura, Shusaku; Tsuzuki, Katsunori; Matsunaga, Takeshi*

Journal of Radioanalytical and Nuclear Chemistry, 314(1), p.403 - 411, 2017/10

 Times Cited Count:5 Percentile:12.06(Chemistry, Analytical)

Fluvial export of particulate and dissolved $$^{137}$$Cs was investigated to reveal its sources and transfer mechanisms in a broadleaved forest catchment using a continuous collection system. The finest size fraction ($$<$$ 75$$mu$$m), consisting of decomposed litter and surface mineral soil, was the dominant fraction in the particulate $$^{137}$$Cs load, although the contribution of coarser size fractions increased during high water discharge in 2014. The dissolved $$^{137}$$Cs originated from the decomposition of $$^{137}$$Cs-contaminated litter. Temporal changes in $$^{137}$$Cs distribution in the litter-mineral soil system indicated that the dissolved $$^{137}$$Cs load will be moderated in several years, while particulate $$^{137}$$Cs load has the potential to continue for a long time.

Journal Articles

Uranium age-dating using in-situ isotope ratios by thermal ionization mass spectrometry for nuclear forensics

Okubo, Ayako; Shinohara, Nobuo; Magara, Masaaki

Journal of Radioanalytical and Nuclear Chemistry, 314(1), p.231 - 234, 2017/10

 Percentile:100(Chemistry, Analytical)

The model date of two enriched uranium materials were determined using a new method for nuclear forensics investigation. In this method, the $$^{230}$$Th/$$^{234}$$U ratio was calculated without spike addition from measured ratios of $$^{230}$$Th/$$^{234}$$Th and $$^{234}$$U/$$^{238}$$U, and calculated $$^{234}$$Th/$$^{238}$$U ratio in secular equilibrium. The obtained model date for the low-enriched uranium material was agreed with the known production date within uncertainty. For the highly enriched uranium material, slightly younger model date than the known production date was obtained. The $$^{234}$$U interference on $$^{234}$$Th counting in thermal ionization mass spectrometry measurement was suspected as a potential cause.

Journal Articles

Separation of Zr in the rubble waste generated at the Fukushima Daiichi Nuclear Power Station

Shimada, Asako; Kameo, Yutaka

Journal of Radioanalytical and Nuclear Chemistry, 311(3), p.1613 - 1618, 2017/03

AA2016-0191.pdf:0.23MB

 Percentile:100(Chemistry, Analytical)

Separation method of Zr using trans uranium resin (TRU resin) was developed. Approximately 100% of Zr, Nb, Bi, Th, and U and a part of Mo and Hg were extracted on the TRU resin from 3 M HNO $$_{3}$$ solution and separated from Li, Be, Mg, Al, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr,Ag, Cd, In, Cs, Ba. Approximately 100% of Zr, Nb, and U were striped from the TRU resin with 0.01 M HF and 10% of Mo, 7.1% of Hg, 77% of Bi, and 20% of Th were also included in the stripping solution. In order to measure $$^{93}$$Zr with inductively coupled plasma mass spectrometry (ICP-MS), Zr has to be separated from Nb and Mo to avoid isobaric interference. Therefore, further purification of Zr using tetra valent actinide resin (TEVA resin) was applied. The developed method was evaluated with the simulated rubble sample solution. Although a part of Zr was eluted during sample loading, most of Zr was extracted on the TRU resin and separated major elements of the rubble sample. Finally, Zr was separated from Nb and Mo with the TEVA resin.

Journal Articles

Dissolved radiocaesium in seawater off the coast of Fukushima during 2013-2015

Fukuda, Miho*; Aono, Tatsuo*; Yamazaki, Shinnosuke*; Nishikawa, Jun*; Otosaka, Shigeyoshi; Ishimaru, Takashi*; Kanda, Jota*

Journal of Radioanalytical and Nuclear Chemistry, 311(2), p.1479 - 1484, 2017/02

 Times Cited Count:2 Percentile:42.02(Chemistry, Analytical)

In order to investigate processes affecting distribution of radiocaesium in seawater in the adjacent region of Fukushima Daiichi Nuclear Power Plant (FDNPP), relationships between $$^{137}$$Cs activity in seawater and physical properties of seawater (salinity, temperature, and potential density) were observed in seven stations within 10 km radius from the FDNPP. As a whole, $$^{137}$$Cs concentrations in seawater were higher in the vicinity of the FDNPP, and were negatively correlated with potential density. From these results, it can be considered that river water discharge or export of seawater from the FDNPP's harbor has affected the higher activity levels of $$^{137}$$Cs in seawater. It was also observed that the $$^{137}$$Cs-elevated seawater can be advected to the 20$$sim$$50 m depths.

Journal Articles

Vertical distributions of global fallout $$^{137}$$Cs and $$^{14}$$C in a Japanese forest soil profile and their implications for the fate and migration processes of Fukushima-derived $$^{137}$$Cs

Koarashi, Jun; Atarashi-Andoh, Mariko; Amano, Hikaru*; Matsunaga, Takeshi

Journal of Radioanalytical and Nuclear Chemistry, 311(1), p.473 - 481, 2017/01

 Times Cited Count:5 Percentile:12.06(Chemistry, Analytical)

Vertical distributions of global fallout $$^{137}$$Cs and $$^{14}$$C were investigated in a Japanese forest soil in 2001. Even 38 years after the fallout, $$^{137}$$Cs was still observed mostly in the uppermost 5 cm. A preferential accumulation of $$^{137}$$Cs was found in a 1-cm-thick transition layer between organic-rich A and underlying B horizons. This unique observation indicated that $$^{137}$$Cs migrated through the A horizon at a rate of 0.20% y$$^{-1}$$ and the transition layer acted as a barrier for $$^{137}$$Cs migration to deeper layers. The vertical distributions of $$^{137}$$Cs and $$^{14}$$C were significantly correlated, suggesting a coupled downward migration of $$^{137}$$Cs and organic matter on a time scale of decades, along the same physical pathways.

Journal Articles

Applicability of polyvinylpolypyrrolidone adsorbent to treatment process of wastes containing uranium

Ohashi, Yusuke; Harada, Masayuki*; Asanuma, Noriko*; Ando, Shion; Tanaka, Yoshio; Ikeda, Yasuhisa*

Journal of Radioanalytical and Nuclear Chemistry, 311(1), p.491 - 502, 2017/01

 Times Cited Count:1 Percentile:64.68(Chemistry, Analytical)

In order to assess the feasibility of method for recovering U from wastes containing uranium (scrap uranium) using polyvinylpolypyrrolidone (PVPP) adsorbent, we have examined the adsorption and desorption behavior of metal species in HCl aqueous solutions dissolving scrap uranium. It was found that the U(VI) species are selectively adsorbed onto PVPP regardless of the presence of a large amount of Na(I) and Al(III), that the adsorbed U(VI) species are desorbed from PVPP column selectively by water. Pure uranium was efficiently recovered from the eluates. From these results, the PVPP resin is expected to be used as the adsorbent in the treatment process of scrap uranium.

Journal Articles

Development of an extraction chromatography method for the analysis of $$^{93}$$Zr, $$^{94}$$Nb, and $$^{93}$$Mo in radioactive contaminated water generated at the Fukushima Daiichi Nuclear Power Station

Shimada, Asako; Kameo, Yutaka

Journal of Radioanalytical and Nuclear Chemistry, 310(3), p.1317 - 1323, 2016/12

 Times Cited Count:2 Percentile:57.25(Chemistry, Analytical)

Journal Articles

Year-round variations in the fluvial transport load of particulate $$^{137}$$Cs in a forested catchment affected by the Fukushima Daiichi Nuclear Power Plant accident

Matsunaga, Takeshi; Nakanishi, Takahiro; Atarashi-Andoh, Mariko; Takeuchi, Erina; Muto, Kotomi; Tsuzuki, Katsunori; Nishimura, Shusaku; Koarashi, Jun; Otosaka, Shigeyoshi; Sato, Tsutomu*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 310(2), p.679 - 693, 2016/11

AA2015-0821.pdf:3.78MB

 Times Cited Count:5 Percentile:23.48(Chemistry, Analytical)

Particulate $$^{137}$$Cs in stream water was collected continuously for two years in order to assess the long-term trend of the $$^{137}$$Cs discharge from the forest environment. Sampling was conducted from December 2011 to December 2013 in a mountainous stream, which received the $$^{137}$$Cs from the Fukushima Daiichi Nuclear Power Plant accident. A seasonal increase in fluvial transport load of particulate $$^{137}$$Cs associated with suspended solids (SS) was observed in August and September when rainfall was abundant. The particulate $$^{137}$$Cs concentration decreased at a faster rate than the rate due to radioactive decay. This decrease might be resulted from redistribution of the easily eroded and polluted soil surface due to heavy rain events such as typhoons. These findings indicate that the particulate $$^{137}$$Cs load was subject to the inter-annual variations in rainfalls, and decreased gradually over a long period of time due to a decrease in $$^{137}$$Cs concentration in SS.

Journal Articles

Photostimulated luminescence applicable to pre-screening of potassium-rich phases in chondritic breccias

Yokoyama, Tatsunori; Misawa, Keiji*; Okano, Osamu*; Minowa, Haruka*; Fukuoka, Takaaki*

Journal of Radioanalytical and Nuclear Chemistry, 310(1), p.81 - 89, 2016/10

 Times Cited Count:1 Percentile:76.09(Chemistry, Analytical)

The identification of alkali-rich components in extraterrestrial materials along with their separation from other constituents is indispensable for subsequent cosmochemical and isotopic studies. This paper presents a simple pre-screening method for such materials by autoradiography using imaging plates (IPs), which is applicable to identification of mm-sized samples containing ca. 30 $$mu$$g of potassium in the Yamayo-74442 chondrite. The detection limit of IPs was $$sim$$1 mBq of $$^{40}$$K under 49 days exposure. The method provides an opportunity to screen meteorite materials non-destructively and to inexpensively check potassium-rich areas and suitable for the $$^{40}$$K-$$^{40}$$Ca and $$^{40}$$K-$$^{40}$$Ar ($$^{39}$$Ar-$$^{40}$$Ar) age determinations.

Journal Articles

Studies on electrochemical behavior of uranium species in choline chloride-urea eutectic for developing electrolytically treating method of uranium-bearing wastes

Ohashi, Yusuke; Asanuma, Noriko*; Harada, Masayuki*; Tanaka, Yoshio; Ikeda, Yasuhisa*

Journal of Radioanalytical and Nuclear Chemistry, 309(2), p.627 - 636, 2016/08

 Times Cited Count:1 Percentile:76.09(Chemistry, Analytical)

As one of methods for recovering uranium from the uranium-bearing wastes, we have proposed the electrolytic deposition method using choline chloride-urea (CCU) which is known as an ambient temperature molten salt. More than 92% of uranium components in inactivated alumina and spent sodium fluoride adsorbent was dissolved into CCU solution. Cyclic voltammograms (CVs) of the solutions prepared by dissolving uranium-bearing wastes in CCU were measured in the potential range of -2.0 to 1.1 V (vs. Ag/AgCl). The one reduction peak was observed around -0.7 V for all solutions. Based on the results of CVs, bulk electrolyses of the solutions dissolving uranium-bearing wastes were also carried out at -1.5V at 80 $$^{circ}$$C. The deposits were formed on a carbon electrode as cathode. Consequently, we confirmed that CCU is effective media for recovering uranium selectively from uranium-bearing waste.

226 (Records 1-20 displayed on this page)