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Journal Articles

Development of new containment tents for rapid worker evacuation from the workspace in emergencies at plutonium fuel handling facilities

Shibanuma, Tomohiro; Hirano, Hiroshi*; Kimura, Yasuhisa; Aita, Takahiro; Yoshida, Masato; Nagai, Yuya; Kitamura, Akihiro

Hoken Butsuri (Internet), 58(2), p.91 - 98, 2023/08

We developed new containment tents that are more easily assembled and effectively functioned, by improving and refurbishing the shortcomings of the conventional tents. The new tents have been already tested in the real airborne contamination situation occurred at the plutonium fuel fabricating facility. The tents appropriately functioned for intended use but other shortcomings emerged and therefore we had modified the structure of the tents further.

Journal Articles

Status report of JAEA-AMS-TONO; Research and technical development in the last four years

Kokubu, Yoko; Fujita, Natsuko; Watanabe, Takahiro; Matsubara, Akihiro; Ishizaka, Chika; Miyake, Masayasu*; Nishio, Tomohiro*; Kato, Motohisa*; Ogawa, Yumi*; Ishii, Masahiro*; et al.

Nuclear Instruments and Methods in Physics Research B, 539, p.68 - 72, 2023/06

 Times Cited Count:0 Percentile:0.02

The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has an accelerator mass spectrometer (JAEA-AMS-TONO-5MV). The spectrometer enabled us to use a multi-nuclide AMS of carbon-14 ($$^{14}$$C), beryllium-10, aluminium-26 and iodine-129, and we have recently been proceeding test measurement of chlorine-36. In response to an increase of samples, we installed a state-of-the-art multi-nuclide AMS with a 300 kV Tandetron accelerator in 2020. Recently, we are driving the development of techniques of isobar separation in AMS and of sample preparation. Ion channeling is applied to remove isobaric interference and we are building a prototype AMS based on this technique for downsizing of AMS. The small sample graphitization for $$^{14}$$C has been attempted using an automated graphitization equipment equipped with an elemental analyzer.

Journal Articles

Present status of the JAEA-AMS-TONO (2021)

Matsubara, Akihiro*; Fujita, Natsuko; Miyake, Masayasu; Ishii, Masahiro*; Watanabe, Takahiro; Kokubu, Yoko; Nishio, Tomohiro*; Ogawa, Yumi; Jinno, Satoshi; Kimura, Kenji; et al.

JAEA-Conf 2022-002, p.55 - 62, 2023/03

We report the present status of the JAEA-AMS-TONO. Particularly, the destructions of varistors used in the beamline equipment will be presented. The cause of the destruction as well as implementation of the safety measures are mentioned.

Journal Articles

Present status of the JAEA-AMS-TONO (2022FY)

Fujita, Natsuko; Miyake, Masayasu; Matsubara, Akihiro*; Ishii, Masahiro*; Watanabe, Takahiro; Jinno, Satoshi; Nishio, Tomohiro*; Ogawa, Yumi; Yamamoto, Yusuke; Kimura, Kenji; et al.

Dai-23-Kai AMS Shimpojiumu Hokokushu, p.1 - 4, 2022/12

The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has three accelerator mass spectrometers. We report the present status of the JAEA-AMS-TONO.

Journal Articles

Project for development of a downsized AMS system based on the surface stripper technique

Fujita, Natsuko; Matsubara, Akihiro; Kimura, Kenji; Jinno, Satoshi; Kokubu, Yoko

Nuclear Instruments and Methods in Physics Research B, 532, p.13 - 18, 2022/12

 Times Cited Count:1 Percentile:34.54(Instruments & Instrumentation)

Over the last decade, significant technological advances were made to downsize the AMS systems. Japan Atomic Energy Agency has started a project for developing a prototype downsized AMS system (with the footprint of the system is 1.9 m $$times$$ 1.9 m) based on the surface stripper technique. Although the system configuration using an ion source, magnets, and detectors is similar to that in conventional systems, there is no tandem accelerator as well as a gas stripper. The ion acceleration is provided in the ion source (maximum ion energy 40 keV). For proof-of-principle experiments, we have planned two steps: (1) Observation of the specular reflection and the dissociation by using a compact electrostatic analyzer located just behind the stripper, and (2) Demonstration of $$^{14}$$C measurement, along with the experimental confirmation of the isobar suppression capability of the surface stripper.

JAEA Reports

Design and production of the valve used in Radioactive Liquid Disposal Facility

Nishimura, Arashi; Okada, Yuji; Sugaya, Naoto; Sonobe, Hiroshi; Kimura, Nobuaki; Kimura, Akihiro; Hanawa, Yoshio; Nemoto, Hiroyoshi

JAEA-Technology 2021-003, 51 Pages, 2021/05

JAEA-Technology-2021-003.pdf:5.55MB

In the Japan Materials Testing Reactor (JMTR), the leakage accidents of radioactive waste liquid were occurred from the tanks and pipes of the liquid waste disposal facility in the JMTR tank-yard building in JFY2014. In order to respond to the accident, obtain the approval of the JAEA to the design and construction method from JFY2016, the tanks and pipes were replaced from JFY2016 to 2019. In the replaced, the production of the tanks and pipes of the liquid waste disposal facility applied Japanese technical standards correspondingly. On the other hand, the valve did not fall under the category of Japanese technical standards. The manufacturing specifications when replacing the valve were decided based on the including the selecting the standards of production and inspection for valves, Fluid properties, experience in JMTR. The production proceeded while carrying out the decided inspection. The valves that passed all the inspections were installed together with the tanks and pipes of the liquid waste, and the finished inspection was performed as a systems. The construction was completed with those inspection passed. This report is summarized valve Design, production and installation.

JAEA Reports

Validation of repairing method for concrete wall of the JMTR tank-yard building

Sugaya, Naoto; Okada, Yuji; Nishimura, Arashi; Sonobe, Hiroshi; Kimura, Nobuaki; Kimura, Akihiro; Hanawa, Yoshio; Nemoto, Hiroyoshi

JAEA-Testing 2020-004, 67 Pages, 2020/08

JAEA-Testing-2020-004.pdf:8.17MB

In the Japan Materials Testing Reactor (JMTR), the leakage accidents of radioactive waste liquid were occurred from the tanks and pipes of the liquid waste disposal facility in the JMTR tank-yard building in JFY2014. In order to respond to the accident, the tanks and pipes were replaced from JFY2016 to 2019. On the other hand, a lot of cracks were occurred on the concreate wall of the tank-yard building when the frame structure supports were fixed to the concrete wall in the replacement work. Thus, it is necessary to repair the concreate wall of the tank-yard building. Especially, some cracks with swelling (cone-shaped fracture) were raised around some anchor bolts (the post-installed chemical anchor bolts) fixed the frame structure supports. The repairing method for the cone-shaped fracture of the concrete wall is standardized, but there was no reference value of tensile strength for the validation of the post-installed chemical anchor bolts after the repairing method. In this report, the repairing method was selected for the cone-shaped fracture on the concreate wall and the reference value of tensile strength for the validation of the post-installed chemical anchor bolts by this repairing method. The mock-ups for repairing cone-shaped fracture were fabricated by the selected repairing method and the tensile tests of the post-installed chemical anchor bolts were performed. From the results, the validation of the repairing method was obtained in this test and it was obvious the repairing of cone-shaped fracture is preferable method for the concreate wall of the JMTR tank-yard building.

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:8 Percentile:72.51(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

Application of ion channeling for downsizing Accelerator Mass Spectrometry (AMS) systems

Matsubara, Akihiro*; Fujita, Natsuko; Ishii, Kunikazu*; Kimura, Kenji*

Hoshasen (Internet), 45(3), p.134 - 138, 2020/04

no abstracts in English

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:3 Percentile:32.21(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

A Study of surface stripper for the AMS system with a footprint below 2 m $$times$$ 2 m

Matsubara, Akihiro; Fujita, Natsuko; Kimura, Kenji

Proceedings of the 8th East Asia Accelerator Mass Spectrometry Symposium and the 22nd Japan Accelerator Mass Spectrometry symposium (EA-AMS 8 & JAMS-22), p.57 - 59, 2020/00

no abstracts in English

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

Radiochemical research for the advancement of $$^{99}$$Mo/$$^{rm 99m}$$Tc generator by (n,$$gamma$$) method

Fujita, Yoshitaka; Seki, Misaki; Namekawa, Yoji*; Nishikata, Kaori; Kimura, Akihiro; Shibata, Akira; Sayato, Natsuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.

KURNS Progress Report 2018, P. 155, 2019/08

no abstracts in English

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:5 Percentile:49.54(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

Measurements of gamma-ray emission probabilities in the decay of americium-244g

Nakamura, Shoji; Terada, Kazushi*; Kimura, Atsushi; Nakao, Taro*; Iwamoto, Osamu; Harada, Hideo; Uehara, Akihiro*; Takamiya, Koichi*; Fujii, Toshiyuki*

Journal of Nuclear Science and Technology, 56(1), p.123 - 129, 2019/01

 Times Cited Count:1 Percentile:11.41(Nuclear Science & Technology)

Accurate data of $$gamma$$-ray emission probabilities are frequently needed when one quantitatively determines the amount of isotope by $$gamma$$-ray measurements or obtains neutron capture cross-sections using them. Americium-243, one of the most important minor actinides, produces $$^{244}$$Am after neutron capture. The 744-keV $$gamma$$-ray decaying from the ground state of $$^{244}$$Am has a relatively large $$gamma$$-ray emission probability c.a. 66%, however, its uncertainty is as large as 29%. The uncertainty of the $$gamma$$-ray emission probability leads to a major factor of the systematic uncertainty on determining an amount of isotope, and therefore the $$gamma$$-ray emission probability was measured by using an activation method and an examined level structure of $$^{244}$$Cm. In this study, the emission probability of 744-keV $$gamma$$ ray was derived as 66.5$$pm$$1.1%, and its uncertainty was improved from 29% to 2%.

Journal Articles

Progress of neutron-capture cross-section measurements promoted by ImPACT project at ANNRI in MLF of J-PARC

Nakamura, Shoji; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*

JAEA-Conf 2018-001, p.199 - 203, 2018/12

Study on cross-section measurements has been promoted for $$^{135}$$Cs among long-lived fission products in ImPACT Project. The feasibility study on $$^{79}$$Se sample preparation also has been conducted to measure its cross sections in future. During the feasibility study, we started the neutron-capture cross-section measurements of stable Se isotopes. This paper reports research progresses on preparation of a radioactive $$^{135}$$Cs sample, neutron irradiation experiments with the Cs sample, and cross-section measurements of stable Se isotopes.

Journal Articles

Analysis of $$^{135}$$Cs/$$^{137}$$Cs isotopic ratio for samples used for neutron capture cross section measurement project by thermal ionization mass spectrometry

Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*; Nakamura, Shoji; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu

JAEA-Conf 2018-001, p.205 - 210, 2018/12

In the ImPACT project, high-precision mass analysis was performed on a $$^{137}$$Cs standard solution for using $$^{135}$$Cs included in the standard solution as an impurity to measure the $$^{135}$$Cs cross-sections. A $$^{137}$$Cs standard solution of only 10Bq (pg order) was analyzed, and the isotope ratio of $$^{135}$$Cs and $$^{137}$$Cs was obtained with an accuracy of 0.5%.

Journal Articles

Neutron irradiation effect of high-density MoO$$_{3}$$ pellets for Mo-99 production

Fujita, Yoshitaka; Nishikata, Kaori; Namekawa, Yoji*; Kimura, Akihiro; Shibata, Akira; Sayato, Natsuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; Zhang, J.*

KURRI Progress Report 2017, P. 126, 2018/08

no abstracts in English

Journal Articles

Research on neutron capture cross sections at J-PARC in ImPACT Project

Nakamura, Shoji; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu; Tsubata, Yasuhiro; Matsumura, Tatsuro; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*

JAEA-Conf 2017-001, p.15 - 22, 2018/01

Neutron nuclear data of long lived fission products (LLFPs) have been required as basic data for the technology of reduce environmental impact involved in high level radioactive wastes (HLW). The innovative large project called by "Impusing Paradigm Change through Disruptive Technologies Program: ImPACT" have been started from October, 2014. In the ImPACT project, some research groups of JAEA engaged in the Project No.2 (Nuclear Reaction Data Measurements), and have started measurements of neutron capture cross-section at J-PARC/MLF/ANNRI. In our research, we selected cesium-135 ($$^{135}$$Cs) nuclide (half life: 2.3$$times$$10$$^{6}$$ yr.) among LLFPs in the HLW, and decided to measure the neutron capture cross-sections of $$^{135}$$Cs. When measurement, the $$^{135}$$Cs sample might contained cecium-137 ($$^{137}$$Cs) as impurities because it's impossible to chemically separate each other. To measure the cross-sections of $$^{135}$$Cs, there should be also needed to know the cross-sections of $$^{137}$$Cs. In this work, sample maintenance also has been examined especially for selen-79 ($$^{79}$$Se) nuclide among LLFPs having difficulty in sample preparations. In this oral session, the outline of our research project will be presented together with a research motivation, situations of past reported data, total schedules, progress, future plans, and some of high light data for neutron capture cross-section measurements.

Journal Articles

High-precision mass analysis of RI sample for cross-section measurements

Nakamura, Shoji; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu

KURRI Progress Report 2016, P. 66, 2017/07

In the ImPACT project, high-precision mass analysis was performed on a $$^{137}$$Cs standard solution for using $$^{135}$$Cs included in the standard solution as an impurity to measure the $$^{135}$$Cs cross-sections. A $$^{137}$$Cs standard solution of only 10Bq (pg order) was analyzed, and the isotope ratio of $$^{135}$$Cs and $$^{137}$$Cs was obtained with an accuracy of 0.5%.

141 (Records 1-20 displayed on this page)