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JAEA Reports

Preparation of carbonate slurry simulating chemical composition of slurry in overflowed high integrity container and evaluation of its characteristics

Horita, Takuma; Yamagishi, Isao; Nagaishi, Ryuji; Kashiwaya, Ryunosuke*

JAEA-Technology 2021-012, 34 Pages, 2021/07

JAEA-Technology-2021-012.pdf:2.1MB
JAEA-Technology-2021-012(errata).pdf:0.18MB

Waste mainly consisting of carbonate precipitates (carbonate slurry) from the Advanced Liquid Processing System (ALPS) and the improved ALPS at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Holdings, Inc. have been storing in the High Integrity Container (HIC). The supernatant solution of carbonate slurry contained in some of HICs were overflowed in April of 2015. The all of level of liquid in the HICs were investigated; however, almost of the HICs were under the level of overflow. The mechanism of overflow suggested to be depending on the difference of the properties of the carbonate slurry such as the retention/release characteristics of the bubbles. Therefore, in order to clarify the mechanism of leakage, the repeatability experiment was carried out by using simulated carbonate slurry. The simulated carbonate slurry was perpetrated by using the same cross-flow filter system of the actual ALPS. Moreover, the preparative conditions for the simulated carbonate slurry were the same as Mg/Ca concentration ratio in inlet water of the ALPS (raw water) and the ALPS operating conditions. The chemical characteristics of simulated carbonate slurries were revealed by ICP-AES, pH meter, etc. The density of the settled slurry layer tended to increase depending on the calcium concentration in the raw water. The bubble injection test was conducted in order to investigate the bubble retention/release behavior in the simulated carbonate slurry layer. The simulated carbonate slurry with high settling density, which was generated by high calcium concentration solution was revealed to retain the injected bubbles. Since the ratio of concentration calcium and magnesium during the carbonate slurry generation is assumed to affect the retention of bubbles in the slurry layer, the information on the composition of raw water is one of important factor for overflow of HICs.

Journal Articles

Improvement of adsorption performances of Sr adsorption fiber and investigation for realizing simple $$^{90}$$Sr analysis

Horita, Takuma; Asai, Shiho*; Konda, Miki; Matsueda, Makoto; Hanzawa, Yukiko; Kitatsuji, Yoshihiro

Bunseki Kagaku, 69(10/11), p.619 - 626, 2020/10

 Times Cited Count:0 Percentile:0.00(Chemistry, Analytical)

We have developed a Sr adsorption fiber for rapid analysis of $$^{90}$$Sr. The prepared Sr adsorption fiber has a Sr-extraction layer that densely retains a Sr-selective extractant, an 18-crown-6 ether derivative, on the fiber surface. Hydrophobic group-containing polymer chains embedded onto the surface of the fiber allow to form a hydrophobic phase, incorporating Sr-selective extractants. This unique surface structure provides high adsorption capacity, leading to rapid and highly efficient adsorption of Sr$$^{2+}$$. The adsorption capacity of the Sr adsorption fiber was 3 times higher than commercially available 18-crown-6 ether derivative-impregnated resin (Sr Resin). The equilibrium adsorption capacity of the Sr adsorption fiber was comparable to the Sr Resin. The retained $$^{90}$$Sr was finally determined by a GM counter. The total analysis time including the Sr adsorption and measurement was about 1 hour.

Journal Articles

Direct quantitation of $$^{135}$$Cs in spent Cs adsorbent used for the decontamination of radiocesium-containing water by laser ablation inductively coupled plasma mass spectrometry

Asai, Shiho*; Ohata, Masaki*; Hanzawa, Yukiko; Horita, Takuma; Yomogida, Takumi; Kitatsuji, Yoshihiro

Analytical Chemistry, 92(4), p.3276 - 3284, 2020/02

 Times Cited Count:5 Percentile:27.38(Chemistry, Analytical)

The long-term safety assessment of spent Cs adsorbents produced during the decontamination of radiocesium-containing water at the Fukushima Daiichi Nuclear Power Plant requires one to estimate their $$^{135}$$Cs content prior to final disposal. $$^{135}$$Cs is usually quantified by inductively coupled plasma mass spectrometry (ICP-MS), which necessitates the elution of Cs from Cs adsorbents. However, this approach suffers from the high radiation dose from $$^{137}$$Cs. To address this challenge, we herein employed laser ablation ICP-MS for direct quantitation of $$^{135}$$Cs in Cs adsorbents and used a model Cs adsorbent prepared by immersion of a commercially available Cs adsorbent into radiocesium-containing liquid waste to verify the developed technique. The use of the $$^{135}$$Cs/$$^{137}$$Cs ratio and $$^{137}$$Cs radioactivity obtained by gamma spectrometry achieved simple and precise quantitation of $$^{135}$$Cs and the resulting $$^{135}$$Cs activity of 0.36 Bq agreed well with that in the original radiocesium-containing liquid waste.

Journal Articles

Determination of $$^{107}$$Pd in Pd purified by selective precipitation from spent nuclear fuel by laser ablation ICP-MS

Asai, Shiho; Ohata, Masaki*; Yomogida, Takumi; Saeki, Morihisa*; Oba, Hironori*; Hanzawa, Yukiko; Horita, Takuma; Kitatsuji, Yoshihiro

Analytical and Bioanalytical Chemistry, 411(5), p.973 - 983, 2019/02

 Times Cited Count:12 Percentile:62.16(Biochemical Research Methods)

Determination of radiopalladium $$^{107}$$Pd is required for ensuring the radiation safety of Pd extracted from spent nuclear fuel for recycling or disposal. We employed laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to simplify an analytical procedure of $$^{107}$$Pd. Pd was separated through selective Pd precipitation reaction from spent nuclear fuel. Laser ablation allows direct measurement of the Pd precipitates, skipping the dissolution and dilution procedure. In this study, $$^{102}$$Pd in natural Pd standard solution was used as an internal standard, taking advantage of its absence in spent nuclear fuel. The Pd precipitate was uniformly embedded on the surface of the centrifugal filter, forming a microscopically thin flat surface of Pd. The resulting homogeneous Pd layer is suitable for obtaining a stable signal ratio of $$^{107}$$Pd/$$^{102}$$Pd. The amount of $$^{107}$$Pd obtained by LA-ICP-MS corresponds to the values obtained by conventional solution nebulization measurement.

Journal Articles

Non-contact and selective Pd separation based on laser-induced photoreduction for determination of $$^{107}$$Pd by ICP-MS; The Relation between separation conditions and Pd recovery

Yomogida, Takumi; Asai, Shiho; Saeki, Morihisa*; Hanzawa, Yukiko; Horita, Takuma; Esaka, Fumitaka; Oba, Hironori*; Kitatsuji, Yoshihiro

Bunseki Kagaku, 66(9), p.647 - 652, 2017/09

 Times Cited Count:2 Percentile:6.78(Chemistry, Analytical)

Palladium-107 is a long-lived fission product, which can be found in high-level radioactive liquid wastes (HLLW). Determination of the $$^{107}$$Pd contents in HLLW is essential to evaluate the long-term safety of HLLW repositories. However, the $$^{107}$$Pd content in HLLW has not been reported because of difficulties in pretreatment for the measurement. In this study, we investigated applicability of laser-induced photoreduction to HLLW solution: it enables a simple and non-contact separation of Pd. The results showed the recovery of 60% was achieved at the conditions: 40% ethanol, 20 min irradiation, 100 mJ of pulse energy. Additionally, major radionuclides and potentially interfering components in ICP-MS were removed from the simulated HLLW over a wide concentration range of Pd from 0.24 to 24 mg L$$^{-1}$$, showing the applicability of the proposed separation technique to HLLW samples.

JAEA Reports

Preliminary missions for the decommissioning of the laboratory building No.1 for the plutonium research program

Segawa, Yukari; Horita, Takuma; Kitatsuji, Yoshihiro; Kumagai, Yuta; Aoyagi, Noboru; Nakada, Masami; Otobe, Haruyoshi; Tamura, Yukito*; Okamoto, Hisato; Otomo, Takashi; et al.

JAEA-Technology 2016-039, 64 Pages, 2017/03

JAEA-Technology-2016-039.pdf:5.24MB

The laboratory building No.1 for the plutonium research program (Bldg. Pu1) was chosen as one of the facilities to decommission by Japan Atomic Energy Agency Reform in September, 2013. The research groups, users of Bldg. Pu1, were driven by necessity to remove used equipment and transport nuclear fuel to other facilities from Bldg. Pu1. Research Group for Radiochemistry proactively established the Used Equipment Removal Team for the smooth operation of the removal in April, 2015. The team classified six types of work into the nature of the operation, removal of used equipment, disposal of chemicals, stabilization of mercury, stabilization of nuclear fuel, transportation of nuclear fuel and radioisotope, and survey of contamination status inside the glove boxes. These works were completed in December, 2015. This report circumstantially shows six works process, with the exception of the approval of the changes on the usage of nuclear fuel in Bldg. Pu1 to help prospective decommission.

Journal Articles

Preparation of Sr adsorptive fiber by impregnating with crown ether derivative for $$^{90}$$Sr measurement

Horita, Takuma; Asai, Shiho; Konda, Miki; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Sugo, Takanobu*; Kitatsuji, Yoshihiro

Bunseki Kagaku, 66(3), p.189 - 193, 2017/03

 Times Cited Count:1 Percentile:3.38(Chemistry, Analytical)

A Sr-selective adsorption fiber was prepared for rapid analysis of $$^{90}$$Sr content by using radiation-induced emulsion graft polymerization and subsequent chemical modification. A polyethylene fiber with a diameter of 13 $$mu$$m was first immersed in a methanol solution of an epoxy-group-containing vinyl monomer, glycidyl methacrylate (GMA), and polyoxyethylene sorbitol ester (Tween20) as a surfactant for graft-polymerization of GMA. Octadecylamine was then bound to a polymer chain extending from the fiber surface providing hydrophobicity to the polymer chain. Dicyclohexano-18-crown-6 (DCH18C6) was finally impregnated onto the polymer chain via a hydrophobic interaction between the octadecyl moiety of the polymer chain and the cyclohexyl moiety of DCH18C6. The fiber surface structure, characterized by DCH18C6 molecules loosely entangled with polymer chains, afforded realizes the rapid and selective adsorption of Sr ions with an adsorption rate approximately 100 times higher than that of a commercially available Sr-selective resin (Sr Resin).

Journal Articles

Determination of $$^{107}$$Pd in Pd recovered by laser-induced photoreduction with inductively coupled plasma mass spectrometry

Asai, Shiho; Yomogida, Takumi; Saeki, Morihisa*; Oba, Hironori*; Hanzawa, Yukiko; Horita, Takuma; Kitatsuji, Yoshihiro

Analytical Chemistry, 88(24), p.12227 - 12233, 2016/12

 Times Cited Count:16 Percentile:53.00(Chemistry, Analytical)

Safety evaluation of a radioactive waste repository requires credible activity estimates confirmed by actual measurements. A long-lived radionuclide, $$^{107}$$Pd, which can be found in radioactive wastes, is one of the difficult-to-measure nuclides and results in a deficit in experimentally determined contents. In this study, a precipitation-based separation method has been developed for the determination of $$^{107}$$Pd with ICP-MS. The photoreduction induced by laser irradiation at 355 nm provides short-time and one-step recovery of Pd. The proposed method was verified by applying it to a spent nuclear fuel sample. In order to efficiently recover Pd, a natural Pd standard was employed as the Pd carrier. The chemical yield of Pd was about 90% with virtually no impurities, allowing accurate quantification of $$^{107}$$Pd.

Oral presentation

Application of ICP-MS to analysis of samples from 1F site at Radioactive Material Analysis and Research Facility

Do, V. K.; Horita, Takuma; Miura, Katsue; Iwasaki, Maho

no journal, , 

Radioactive Material Analysis and Research Facility has been recently established to support the analysis of samples including fuel debris and radioactive wastes from the decommissioning of Fukushima Daiichi Nuclear Power Station (1F). ICP-MS is considered as a potential analytical tool for long-lived nuclides in fuel debris because of its superior sensitivity. Moreover, the use of ICP-MS is aimed to increase the analysis capacity, which make possible to repeat measurements in order to obtain precise results and to reduce exposed dose of analysts because ICP-MS is much more rapid than radiometric methods. Employing latest advanced technologies, a triple quadrupole ICP-MS, Agilent 8900 (ICP-QQQ-MS), enables to suppress the isobaric interference. In this presentation, we report some demonstrative separations of difficult-to-measure nuclides using the ICP-QQQ-MS system. The obtained results indicate that the separations are possible with suitable reaction gases.

Oral presentation

Isotope ratio measurement of Pd recovered from spent nuclear fuel with LA-ICP-MS

Asai, Shiho; Ohata, Masaki*; Yomogida, Takumi; Saeki, Morihisa*; Oba, Hironori*; Hanzawa, Yukiko; Horita, Takuma; Kitatsuji, Yoshihiro

no journal, , 

Safe and cost-effective disposal of radioactive wastes requires reliable evaluation of the amount of the radionuclides found in such wastes. Measurement of $$^{107}$$Pd, one of the radionuclides that are necessary to be evaluated, is associated with highly radioactive sample (e.g., spent nuclear fuel sample), resulting in only a few data in published forms. We separated Pd as a precipitate from a spent nuclear fuel sample and then determined the precise amount of $$^{107}$$Pd. However, the method needed dissolution of the Pd precipitate to carry it to the sample introduction system of ICP-MS. In this study, we tried direct measurement of the Pd precipitate with laser-ablation (LA)-ICP-MS that enables solid sample measurement. The diameters of the recovered Pd precipitates were less than 500 nm, which is much smaller than the ablation spot. This allowed Pd to be uniformly vaporized, leading to sufficiently stable signals with high precisions equivalent to those of conventional ICP-MS.

Oral presentation

Separation of platinum-group metals from radioactive waste liquid by laser induced particle formation

Saeki, Morihisa*; Asai, Shiho; Yomogida, Takumi; Hanzawa, Yukiko; Taguchi, Tomitsugu*; Horita, Takuma; Kitatsuji, Yoshihiro; Oba, Hironori*

no journal, , 

Platinum-group metals (PGMs), such as Pd, Ru, and Rh are generated by nuclear fission of U and can be found in spent nuclear fuel (SNF) and high-level radioactive waste (HLW). Separation techniques for PGMs from HLW have been investigated for the safety assessment of HLW and the reuse of PGMs as resources. Among such PGMs, only Pd has a long-lived radionuclide $$^{107}$$Pd. Accordingly, the precise measurement of the amount of $$^{107}$$Pd in HLW is essential for the long-term safety management of HLW. The determination of $$^{107}$$Pd requires a reliable separation technique that allows selective Pd recovery with high purity. We developed a new separation technique specialized for PGMs. The technique involves UV-laser irradiation that induces selective reduction of ions of PGMs. The reduced PGMs can be readily recovered as precipitates. At the conference, the separation performances of PGMs and some applications of our technique will be discussed.

Oral presentation

Study on applicability of ICP-QQQ-MS to the analysis of Np-237 at Okuma Analysis and Research Center

Horita, Takuma; Iwasaki, Maho

no journal, , 

no abstracts in English

Oral presentation

Development of crown-ether-derivative impregnated fiber for in-situ analysis of $$^{90}$$Sr; Study of safe Sr adsorption with no nitric acid

Konda, Miki; Horita, Takuma; Asai, Shiho; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Sugo, Takanobu*; Ishimori, Kenichiro; Kameo, Yutaka

no journal, , 

no abstracts in English

Oral presentation

Development of an analytical method for nickel isotopes using an automated sample preparation system and ICP-QQQ-MS

Do, V. K.; Kitamura, Kiyoshi; Horita, Takuma; Furuse, Takahiro

no journal, , 

We report an application of automated devices for multi-step chemical separation for nickel and an idea of subsequent quantification for Ni-59 using ICP-QQQ-MS. Nickel is separated on our selected automated instruments applying a conventional separation scheme. The obtained chemical recovery for Ni standard carrier was 89.8% (relative standard deviation, RSD of 2.9%, n = 3), which is consistent with the manually obtained recovery of 87.0% (RSD = 2.2%, n = 3). The quantification of Ni-59 by ICP-QQQ-MS was examined. Accordingly, the intensity of 59Ni could be deduced from an intensity correction curve for natural isotopes of nickel. The proposed analytical method is more rapid and less laborious, being expected to reduce radiation exposure to workers.

Oral presentation

Development of analytical techniques of $$^{93}$$Zr and $$^{93}$$Mo in fuel debris by ICP-MS/MS

Horita, Takuma; Akimoto, Yuji*; Kikuchi, Hikaru*; Do, V. K.

no journal, , 

no abstracts in English

Oral presentation

Determination of long-lived radionuclide $$^{135}$$Cs in Cs adsorbent by LA-ICP-MS

Asai, Shiho*; Ohata, Masaki*; Hanzawa, Yukiko; Yomogida, Takumi; Horita, Takuma; Kitatsuji, Yoshihiro

no journal, , 

A large amount of Cs adsorbents left over after decontamination of waste water has continued to accumulate in the Fukushima Daiichi Nuclear Power Plant. For safe disposal of such Cs adsorbents, estimation of the radioactivity is crucial. A long-lived beta emitting nuclide $$^{135}$$Cs which is captured in the Cs adsorbents along with a major radiation contributor $$^{137}$$Cs. Different from $$^{137}$$Cs which can be measured in gamma spectrometry, the activity of $$^{135}$$Cs is generally measured in liquid form, requiring elution of Cs$$^{+}$$. However, high radiation from the Cs adsorbents hampers the operations. In this study, we applied LA-ICP-MS which allows direct measurement of Cs adsorbent. With $$^{135}$$Cs /$$^{137}$$Cs given by LA-ICP-MS, $$^{135}$$Cs can be calculated by combining a measured $$^{137}$$Cs radioactivity. A radiocesium-containing sample was used to verify the proposed method. The results agreed well with those obtained through the measurement of Cs-separated solution.

Oral presentation

Development of rational analytical technique of $$^{151}$$Sm by ICP-MS/MS

Horita, Takuma; Akimoto, Yuji*; Do, V. K.

no journal, , 

Samarium-151($$^{151}$$Sm) can be measured by liquid scintillation counting (LSC) or inductively coupled plasma mass spectrometry (ICP-MS). While the former method requires a complete radiochemical separation, the latter one must solve the isobaric interference from Europium-151 ($$^{151}$$Eu). In this study, we have been developing an analytical technique for $$^{151}$$Sm by ICP-tandem MS(ICP-MS/MS). The recent advances of MS/MS mode with a collision/reaction cell in mass spectrometry may enable sufficient removal of the mass spectroscopic interferences. Moreover, compared to LSC, ICP-MS is more rapid and more selective, and thus, it can simplify pretreatment process. As preliminary experiments, the selection of reaction gas for the separation of $$^{151}$$Sm from $$^{151}$$Eu were examined by checking the product ions of $$^{147}$$Sm and $$^{151}$$Eu produced by reactions with the various gases (H$$_{2}$$, O$$_{2}$$, NH$$_{3}$$, and N$$_{2}$$O). Our obtained data showed that in the reaction with NH$$_{3}$$, Sm formed a product ion at mass shift of 16, while the reaction tendency of Eu is different. Accordingly, the counts of $$^{147}$$Sm and $$^{151}$$Eu at the mass shift of 16 were 9842 [cps/$$mu$$g/L] and 162 [cps/$$mu$$g/L], respectively. The difference in reactivity of Sm and Eu to NH$$_{3}$$ gas can reduce interference of the $$^{151}$$Eu to the measurement of $$^{151}$$Sm.

Oral presentation

Annual outcomes Okuma Analysis and Research Center 2018

Furuse, Takahiro; Do, V. K.; Akutsu, Hideyuki; Horita, Takuma

no journal, , 

We will report status of development of analytical techniques and facilities for Okuma Analysis and Research Center as 2018 annual outcomes. In regard to development of analytical techniques, we will report rapid and efficient analytical methods for nuclides using ICP-MS and automated systems.

Oral presentation

Direct measurement of $$^{135}$$Cs in Cs adsorbent used for water decontamination by laser-ablation ICP-MS

Asai, Shiho*; Ohata, Masaki*; Hanzawa, Yukiko; Horita, Takuma; Yomogida, Takumi; Kitatsuji, Yoshihiro

no journal, , 

A large amount of spent Cs adsorbents used for decontaminating water in Fukushima Daiichi Nuclear Power Station are stored in the site. To dispose them safely, the estimation of $$^{135}$$Cs activity along with that of $$^{137}$$Cs is indispensable. $$^{135}$$Cs is generally measured by ICP-MS, which required the sample to be prepared in liquid form and thus the elution of Cs from the Cs adsorbents is essential. However, this approach suffers from the high radiation dose from $$^{137}$$Cs. In this study, we quantified $$^{135}$$Cs in a Cs adsorbent using the $$^{135}$$Cs/$$^{137}$$Cs ratio obtained by LA-ICP-MS and $$^{137}$$Cs radioactivity obtained by gamma spectrometry. To evaluate the applicability, we employed a $$^{135}$$Cs -containing water sample to prepare a model spent Cs adsorbent with a certified $$^{135}$$Cs activity. The resulting $$^{135}$$Cs activity of 0.36 Bq calculated by $$^{135}$$Cs /$$^{137}$$Cs ratio of 0.41 $$pm$$ 0.02 and $$^{137}$$Cs activity agreed well with that of the originally determined $$^{135}$$Cs activity in the model spent Cs adsorbent, demonstrating that the proposed technique has high validity to $$^{135}$$Cs determination of a real sample.

Oral presentation

Irradiation experiments of simulated carbonate slurry in HIC, 5; Effect of chemical composition of slurry on its physical property

Yamagishi, Isao; Kato, Tomoaki; Horita, Takuma

no journal, , 

no abstracts in English

37 (Records 1-20 displayed on this page)