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Journal Articles

Developing accelerator mass spectrometry capabilities for anthropogenic radionuclide analysis to extend the set of oceanographic tracers

Hain, K.*; Martschini, M.*; G$"u$lce, F.*; Honda, Maki; Lachner, J.*; Kern, M.*; Pitters, J.*; Quinto, F.*; Sakaguchi, Aya*; Steier, P.*; et al.

Frontiers in Marine Science (Internet), 9, p.837515_1 - 837515_17, 2022/03

Recent major advances in accelerator mass spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA) regarding detection efficiency and isobar suppression have opened possibilities for the analysis of additional long-lived radionuclides at ultra-low environmental concentrations. These radionuclides, including $$^{233}$$U, $$^{135}$$Cs, $$^{99}$$Tc and $$^{90}$$Sr, will become important for oceanographic tracer application due to their generally conservative behavior in ocean water. In particular, the isotope ratios $$^{233}$$U/$$^{236}$$U and $$^{137}$$Cs/$$^{135}$$Cs have proven to be powerful fingerprints for emission source identification as they are not affected by elemental fractionation. Improved detection efficiencies allowed us to analyze all major long-lived actinides, i.e. $$^{236}$$U, $$^{237}$$Np, $$^{239, 240}$$Pu, $$^{241}$$Am as well as the very rare $$^{233}$$U, in the same 10 L water samples of an exemplary depth profile from the northwest Pacific Ocean. Especially for $$^{90}$$Sr analysis, our new approach has already been validated for selected reference materials (e.g. IAEA-A-12) and is ready for application in oceanographic studies. We estimate that a sample volume of only (1-3) L ocean water is sufficient for $$^{90}$$Sr as well as $$^{135}$$Cs analysis, respectively.

Journal Articles

${it In situ}$ spectrometry of terrestrial gamma rays using portable germanium detectors in area of 80 km radius around the Fukushima Daiichi Nuclear Power Plant

Mikami, Satoshi; Tanaka, Hiroyuki*; Okuda, Naotoshi*; Sakamoto, Ryuichi*; Ochi, Kotaro; Uno, Kiichiro*; Matsuda, Norihiro; Saito, Kimiaki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 20(4), p.159 - 178, 2021/12

In order to know the background radiation level where the area affected by the Fukushima Daiichi Nuclear Power Plant accident in 2011, terrestrial gamma rays had been measured by using portable germanium detectors repeatedly from 2013 through 2019, at 370 locations within 80 km radius area centered on the Fukushima Daiichi Nuclear Power Plant. Radioactive concentrations of Uranium 238, Thorium 232, Potassium 40 and kerma rates in air due to terrestrial gamma rays were obtained at those locations based on the method of ICRU report 53. Averaged concentrations of $$^{238}$$U, $$^{232}$$Th and $$^{40}$$K were 18.8, 22.7, 428 Bq/kg, respectively, and kerma rate in air over the area was found to be 0.0402 $$mu$$Gy/h. The obtained kerma rates in air were compared to those reported in literatures. It was confirmed that the data were correlated with each other, and were agreed within the range of their uncertainty. This is because the kerma rate in air due to terrestrial gamma rays is depend on geology. The similar trend to previous findings was observed that the kerma rate in air at locations geologically classified as Mesozoic era, Granite and Rhyolite were statistically significantly higher than the others.

Journal Articles

Incorporation of U, Pb and rare earth elements in calcite through crystallisation from amorphous calcium carbonate; Simple preparation of reference materials for microanalysis

Miyajima, Yusuke*; Saito, Ayaka*; Kagi, Hiroyuki*; Yokoyama, Tatsunori; Takahashi, Yoshio*; Hirata, Takafumi*

Geostandards and Geoanalytical Research, 45(1), p.189 - 205, 2021/03

 Times Cited Count:0 Percentile:0.01(Geochemistry & Geophysics)

Uncertainty for elemental and isotopic analyses of calcite by LA-ICP-MS is largely controlled by the homogeneity of the reference materials (RMs) used for normalization and validation. In order to produce calcite RMs with homogeneous elemental and isotopic compositions, we incorporated elements including U, Pb, and rare earth elements into calcite through heat- and pressure-induced crystallization from amorphous calcium carbonate that was precipitated from element-doped reagent solution. X-ray absorption spectra showed that U was present as U(VI) in the synthesized calcite, probably with a different local structure from that of aqueous uranyl ions. The uptake rate of U by our calcite was higher in comparison to synthetic calcite of previous studies. Variations of element mass fractions in the calcite were better than 12% 2RSD, mostly within 7%. The $$^{207}$$Pb/$$^{206}$$Pb ratio in the calcite showed $$<$$1% variations, while the $$^{238}$$U/$$^{206}$$Pb ratio showed 3-24% variations depending on element mass fractions. Using the synthetic calcite as primary RMs, we could date a natural calcite RM, WC-1, with analytical uncertainty as low as $$<$$3%. The method presented can be useful to produce calcite with controlled and homogeneous element mass fractions, and is a promising alternative to natural calcite RMs for U-Pb geochronology.

Journal Articles

True coincidence summing correction for cylindrical volume samples in $$gamma$$-ray spectrometry

Yamada, Takashi*; Asai, Masato; Yonezawa, Chushiro*; Kakita, Kazutoshi*; Hirai, Shoji*

Radioisotopes, 69(9), p.287 - 297, 2020/09

We have confirmed that the commercially available Japanese `standard' gamma-ray analysis programs do not consider the effect of sample volume in calculating true coincidence summing (TCS) corrections, which results in underestimation of $$^{134}$$Cs radioactivity in cylindrical volume samples. In this work, we have developed and examined a practical TCS correction method for general Ge detectors which consider the effect of sample volume properly, and have confirmed that this method can reduce the $$^{134}$$Cs radioactivity underestimation to less than 1%.

Journal Articles

A Cubic CeBr$$_{3}$$ gamma-ray spectrometer suitable for the decommissioning of the Fukushima Daiichi Nuclear Power Station

Kaburagi, Masaaki; Shimazoe, Kenji*; Otaka, Yutaka*; Uenomachi, Mizuki*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*; et al.

Nuclear Instruments and Methods in Physics Research A, 971, p.164118_1 - 164118_8, 2020/08

 Times Cited Count:3 Percentile:76.41(Instruments & Instrumentation)

Journal Articles

Measurement of cesium isotopic ratio by thermal ionization mass spectrometry for neutron capture reaction studies on $$^{135}$$Cs

Shibahara, Yuji*; Nakamura, Shoji; Uehara, Akihiro*; Fujii, Toshiyuki*; Fukutani, Satoshi*; Kimura, Atsushi; Iwamoto, Osamu

Journal of Radioanalytical and Nuclear Chemistry, 325(1), p.155 - 165, 2020/07

 Times Cited Count:0 Percentile:0.01(Chemistry, Analytical)

The measurements of isotopic ratios of Cs samples by thermal ionization mass spectrometry were performed for the analysis of their samples used to evaluate nuclear data obtained for $$^{135}$$Cs. To obtain a high intensity and stable ion beam, the effects of additive agents on the ionization of Cs were examined. The effect of silicotungstic acid on the ionization of Cs was the largest among the additive agents studied in the present study, while the silicotungstic acid also showed the largest isobaric interference of polyatomic ions. It was demonstrated that as small as 2$$times$$10$$^{-13}$$ g of a Cs sample was sufficient to achieve the analytical precision required to measure the $$^{135}$$Cs/$$^{137}$$Cs ratio in the case where an additive agent of TaO/glucose was employed. After examining of the analytical conditions, such as the interference effect due to Ba, the measurements of the isotopic ratios of two Cs samples used in our study using TIMS were conducted, and it was discussed how much the ratios contributed to evaluation of the neutron capture cross-section of $$^{135}$$Cs.

Journal Articles

Vertical distributions of Iodine-129 and iodide in the Chukchi Sea and Bering Sea

Miwa, Kazuji; Obata, Hajime*; Suzuki, Takashi

Journal of Nuclear Science and Technology, 57(5), p.537 - 545, 2020/05

 Times Cited Count:1 Percentile:23.13(Nuclear Science & Technology)

This study investigated the vertical distribution of Iodine-129 ($$^{129}$$I) which is mainly produced by European nuclear reprocessing plants in the Chukchi Sea and Bering Sea. $$^{129}$$I was found to be distributed almost uniformly in fallout level, and an increasing in $$^{129}$$I concentration levels caused by high $$^{129}$$I water inflow from the Atlantic Ocean was not observed. Additionally, we revealed the vertical distribution of iodide, one chemical form of iodine, from the Bering Shelf area to the Chukchi Sea for the first time. The increasing tendency of iodide near sea bottom was observed.

Journal Articles

Measurements of thermal-neutron capture cross-section of cesium-135 by applying mass spectrometry

Nakamura, Shoji; Shibahara, Yuji*; Kimura, Atsushi; Iwamoto, Osamu; Uehara, Akihiro*; Fujii, Toshiyuki*

Journal of Nuclear Science and Technology, 57(4), p.388 - 400, 2020/04

 Times Cited Count:1 Percentile:23.13(Nuclear Science & Technology)

The thermal-neutron capture cross-section ($$sigma_{0}$$) and resonance integral(I$$_{0}$$) were measured for the $$^{135}$$Cs(n,$$gamma$$)$$^{136}$$Cs reaction by an activation method and mass spectrometry. We used $$^{135}$$Cs contained as an impurity in a normally available $$^{137}$$Cs standard solution. An isotope ratio of $$^{135}$$Cs and $$^{137}$$Cs in a standard $$^{137}$$Cs solution was measured by mass spectrometry to quantify $$^{135}$$Cs. The analyzed $$^{137}$$Cs samples were irradiated at the hydraulic conveyer of the research reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Wires of Co/Al and Au/Al alloys were used as neutron monitors to measure thermal-neutron fluxes and epi-thermal Westcott's indices at an irradiation position. A gadolinium filter was used to measure the $$sigma_{0}$$, and a value of 0.133 eV was taken as the cut-off energy. Gamma-ray spectroscopy was used to measure induced activities of $$^{137}$$Cs, $$^{136}$$Cs and monitor wires. On the basis of Westcott's convention, the $$sigma_{0}$$ and I$$_{0}$$ values were derived as 8.57$$pm$$0.25 barn, and 45.3$$pm$$3.2 barn, respectively. The $$sigma_{0}$$ obtained in the present study agreed within the limits of uncertainties with the past reported value of 8.3$$pm$$0.3 barn.

Journal Articles

Guidance for ${it in situ}$ gamma spectrometry intercomparison based on the information obtained through five intercomparisons during the Fukushima mapping project

Mikami, Satoshi; Ishikawa, Daisuke*; Matsuda, Hideo*; Hoshide, Yoshifumi*; Okuda, Naotoshi*; Sakamoto, Ryuichi*; Saito, Kimiaki

Journal of Environmental Radioactivity, 210, p.105938_1 - 105938_7, 2019/12

 Times Cited Count:1 Percentile:10.3(Environmental Sciences)

Five intercomparisons of in situ $$gamma$$ spectrometry by 6-7 participating teams have been conducted between December 2011 and August 2015 at sites in Fukushima prefecture which affected by the fallout of FDNPS accident occurred in March 2011. The evaluated deposition densities agreed within 5-6% in terms of coefficient of variation (CV) for radiocesium ($$^{134}$$Cs and $$^{137}$$Cs), by our best achievement, and the ratio of $$^{134}$$Cs/$$^{137}$$Cs in deposition density agreed within 1-2% in CV, through five intercomparisons. These results guarantee the accuracy of the measurements of the mapping project. Two different methods for intercomparison were conducted: (1) sequential measurements at an identical point; and (2) simultaneous measurements in a narrow area within 3 m radius. In a comparison between the two methods at a site, no significant difference was observed between the results. The standard protocols for the two different intercomparison methods were proposed based on our experience.

Journal Articles

Activation measurement for thermal-neutron capture cross-section of Cesium-135

Nakamura, Shoji; Kimura, Atsushi; Iwamoto, Osamu; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*

KURNS Progress Report 2018, P. 106, 2019/08

Under the ImPACT project, the neutron capture cross-section measurements of Cesium-135 ($$^{135}$$Cs) among the long-lived fission products have been performed at Kyoto University. This paper reports measurements of the thermal-neutron capture cross-section of $$^{135}$$Cs at the Kyoto University Research Reactor (KUR).

Journal Articles

Measurements of thermal-neutron capture cross-section and resonance integral of neptunium-237

Nakamura, Shoji; Kitatani, Fumito; Kimura, Atsushi; Uehara, Akihiro*; Fujii, Toshiyuki*

Journal of Nuclear Science and Technology, 56(6), p.493 - 502, 2019/06

 Times Cited Count:3 Percentile:57.07(Nuclear Science & Technology)

The thermal-neutron capture cross-section($$sigma_{0}$$)and resonance integral(I$$_{0}$$) were measured for the $$^{237}$$Np(n,$$gamma$$)$$^{238}$$Np reaction by an activation method. A method with a Gadolinium filter, which is similar to the Cadmium difference method, was used to measure the $$sigma_{0}$$ with paying attention to the first resonance at 0.489 eV of $$^{237}$$Np, and a value of 0.133 eV was taken as a cut-off energy. Neptunium-237 samples were irradiated at the pneumatic tube of the Kyoto University Research Reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Wires of Co/Al and Au/Al alloys were used as monitors to determine thermal-neutron fluxes and epi-thermal Westcott's indices at an irradiation position. A $$gamma$$-ray spectroscopy was used to measure activities of $$^{237}$$Np, $$^{238}$$Np and neutron monitors. On the basis of Westcott's convention, the $$sigma_{0}$$ and I$$_{0}$$ values were derived as 186.9$$pm$$6.2 barn, and 1009$$pm$$90 barn, respectively.

Journal Articles

Quantitative determination of total cesium in highly active liquid waste by using liquid electrode plasma optical emission spectrometry

Do, V. K.; Yamamoto, Masahiko; Taguchi, Shigeo; Takamura, Yuzuru*; Surugaya, Naoki; Kuno, Takehiko

Talanta, 183, p.283 - 289, 2018/06

 Times Cited Count:9 Percentile:50.51(Chemistry, Analytical)

We develop a novel analytical method employing liquid electrode plasma optical emission spectrometry for measurement of total cesium in highly active liquid wastes. Limit of detection and limit of quantification are 0.005 mg/L and 0.02 mg/L, respectively. The method is validated and applied to the real samples.

Journal Articles

Ion desorption from bulk cesium chloride at moderate temperature ($$<$$500$$^{circ}$$C) under electric field

Baba, Yuji; Shimoyama, Iwao

e-Journal of Surface Science and Nanotechnology (Internet), 16, p.53 - 59, 2018/03

Surface ionization for cesium chloride and Cs-adsorbed soil has been investigated. For cesium chloride, neutral cesium was desorbed around 645$$^{circ}$$C which is close to the melting point of cesium. While Cs$$^{+}$$ ion was desorbed from 400$$^{circ}$$C. The ratio of desorbed ions and neutrals (Cs$$^{+}$$/Cs$$^{0}$$) has a maximum around 410 $$^{circ}$$C. Temperature dependence of Cs$$^{+}$$/Cs$$^{0}$$ was analyzed using Saha-Langmuir equation, As a result, it was found that the temperature maximum is due to the changes of the surface work function induced by the phase transition of CsCl.

Journal Articles

Inductively coupled plasma-mass spectrometry

Esaka, Fumitaka

Analytical Sciences, 33(10), p.1097 - 1098, 2017/10

 Times Cited Count:2 Percentile:73.93(Chemistry, Analytical)

Inductively coupled plasma-mass spectrometry (ICP-MS) is widely used in various fields such as environmental, geological, and clinical sciences. In this report, recent advances of the ICP-MS analysis and expected applications are described.

Journal Articles

High precision analysis of isotopic composition for samples used for nuclear cross-section measurements

Shibahara, Yuji*; Hori, Junichi*; Takamiya, Koichi*; Fujii, Toshiyuki*; Fukutani, Satoshi*; Sano, Tadafumi*; Harada, Hideo

EPJ Web of Conferences, 146, p.03028_1 - 03028_4, 2017/09

 Times Cited Count:0 Percentile:0.08

Journal Articles

Challenges for enhancing Fukushima environmental resilience, 3; Development of measurement and evaluation techniques for the environmental radiation monitoring

Sanada, Yukihisa

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 59(7), p.418 - 422, 2017/07

no abstracts in English

Journal Articles

Application of automated particle screening for effective analysis of individual uranium particles by thermal ionization mass spectrometry

Esaka, Fumitaka; Suzuki, Daisuke; Yomogida, Takumi; Magara, Masaaki

Analytical Methods, 8(7), p.1543 - 1548, 2016/02


 Times Cited Count:7 Percentile:56.39(Chemistry, Analytical)

The isotope ratio analysis of individual uranium particles in environmental samples taken at nuclear facilities is important to clarify their origins for nuclear safeguards. In the present study, automated particle screening was used to select uranium particles prior to precise isotope ratio analysis by thermal ionization mass spectrometry (TIMS). As a result, molecular ion interferences on the uranium mass region were able to be almost completely avoided in the analysis of real inspection samples using APM-TIMS. Therefore, the performance of APM-TIMS was sufficient for obtaining isotope ratio data of individual particles without molecular ion interferences.

Journal Articles

In situ $$gamma$$ spectrometry intercomparison in Fukushima, Japan

Mikami, Satoshi; Sato, Shoji*; Hoshide, Yoshifumi*; Sakamoto, Ryuichi*; Okuda, Naotoshi*; Saito, Kimiaki

Hoken Butsuri, 50(3), p.182 - 188, 2015/09

Intercomparison of in situ $$gamma$$ spectrometry was organized at a site contaminated by the radioactive fallout that originated from the Fukushima Dai-ichi Nuclear Power Plant accident. This intercomparison was conducted by eight teams from four different institutions, which have contributed to the government-led project to construct distribution maps of radionuclides deposited on the ground soil. The resultant $$^{134}$$Cs and $$^{137}$$Cs inventories evaluated by the participants agreed within 6% of the coefficient of variation, after correction for inhomogeneous distribution of the air dose rate. The evaluated $$^{40}$$K inventories agreed within 4% of the coefficient of variation. The authors estimated that these results were in good agreement for creating distribution maps of the radionuclide inventory in the ground soil.

Journal Articles

Transmission secondary ion mass spectrometry using 5 MeV C$$_{60}$$$$^{+}$$ ions

Nakajima, Kaoru*; Nagano, Kengo*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Hirata, Koichi*; Kimura, Kenji*

Applied Physics Letters, 104(11), p.114103_1 - 114103_4, 2014/03

 Times Cited Count:5 Percentile:26.55(Physics, Applied)

Journal Articles

Development of RIMS apparatus for isotope analysis of Calcium nuclear waste materials

Miyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo

Journal of Nuclear Science and Technology, 43(4), p.305 - 310, 2006/04

 Times Cited Count:13 Percentile:68.77(Nuclear Science & Technology)

We are developing an resonance ionization spectrometric apparatus aiming at an analysis of a radioactive isotope of calcium ($$^{41}$$Ca) in nuclear waste materials. The developed system consists of the reference laser whose frequency was locked on a Doppler-free absorption line of 85Rb and the computer-controlled fringe offset lock system which transfer frequency stability of the reference laser to slave lasers for Ca excitation. With heterodyne spectroscopy and laser induced fluorescence spectroscopy of Ca, it was confirmed that the developed apparatus was suitable for resonance ionization spectrometric analysis.

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