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Journal Articles

Application of multiple $$gamma$$-ray detection to long-lived radioactive nuclide determination in environmental samples

Oshima, Masumi*; Goto, Jun*; Haraga, Tomoko; Kin, Tadahiro*; Ikebe, Yurie*; Seto, Hirofumi*; Bamba, Shigeru*; Shinohara, Hirofumi*; Morimoto, Takao*; Isogai, Keisuke*

Journal of Nuclear Science and Technology, 57(6), p.663 - 670, 2020/06

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Gamma-gamma coincidence measurement utilized in $$gamma$$-ray spectroscopy experiments is well known to be effective for the improvement of signal-to-noise ratio in a $$gamma$$-ray spectrum. We study its applicability to determination of long-lived radioactive nuclides in environmental samples. The $$gamma$$-ray simulation code Geant 4.10.2 was used. We took up 35 nuclides which need to be determined for the evaluation of fission product leakage at the nuclear accident in the Fukushima nuclear power plants. Among them five nuclides of $$^{60}$$Co, $$^{94}$$Nb, $$^{134}$$Cs, $$^{152}$$Eu and $$^{154}$$Eu can be the objectives of the multiple $$gamma$$-ray detection method. The simulation results indicate that the signal-to-noise ratio can be improved by a factor between 9.8 and 283, and the detection limit by a factor between 2.7 and 8.5 relative to the singles measurement, implying that the method can be well applied to the determination of the long-lived radioactive nuclides.

Journal Articles

Sensitivity of charged particle activation analysis for long-lived radioactive nuclide determination

Oshima, Masumi*; Yamaguchi, Yurie*; Asai, Masato; Tsukada, Kazuaki; Goto, Jun*; Bamba, Shigeru*; Bi, C.*; Morimoto, Takao*

Journal of Nuclear Science and Technology, 56(9-10), p.866 - 872, 2019/09

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

Sensitivity of charged particle activation analysis with 8 MeV proton beam was studied for determination of 35 long-lived radioactive nuclides. Reaction cross sections for those nuclides were estimated with ALICE-91 code and isomer yield ratios were estimated from those of neighboring isotopes by taking into account their spins and parities. It was found that the proposed charged particle activation analysis should show high sensitivity for the determination of several hardly measurable nuclides with long half-lives such as $$^{135}$$Cs, $$^{244}$$Pu, $$^{129}$$I, $$^{126}$$Sn, $$^{93}$$Mo, $$^{107}$$Pd, $$^{236}$$U, $$^{248}$$Cm, and $$^{237}$$Np.

JAEA Reports

Decommissioning activities and R&D of nuclear facilities in the second midterm plan

Terunuma, Akihiro; Mimura, Ryuji; Nagashima, Hisao; Aoyagi, Yoshitaka; Hirokawa, Katsunori*; Uta, Masato; Ishimori, Yuu; Kuwabara, Jun; Okamoto, Hisato; Kimura, Yasuhisa; et al.

JAEA-Review 2016-008, 98 Pages, 2016/07

JAEA-Review-2016-008.pdf:11.73MB

Japan Atomic Energy Agency formulated the plan to achieve the medium-term target in the period of April 2010 to March 2015(hereinafter referred to as "the second medium-term plan"). JAEA determined the plan for the business operations of each year (hereinafter referred to as "the year plan"). This report is that the Sector of Decommissioning and Radioactive Waste Management has summarized the results of the decommissioning technology development and decommissioning of nuclear facilities which were carried out in the second medium-term plan.

Journal Articles

Welding technology on sector assembly of the JT-60SA vacuum vessel

Shibama, Yusuke; Okano, Fuminori; Yagyu, Junichi; Kaminaga, Atsushi; Miyo, Yasuhiko; Hayakawa, Atsuro*; Sagawa, Keiich*; Mochida, Tsutomu*; Morimoto, Tamotsu*; Hamada, Takashi*; et al.

Fusion Engineering and Design, 98-99, p.1614 - 1619, 2015/10

 Times Cited Count:3 Percentile:32.14(Nuclear Science & Technology)

The JT-60SA vacuum vessel (150 tons) is a double wall torus structure and the maximum major radius of 5.0 m and height of 6.6 m. The manufacturing design concept is that the vessel is split in the 10 toroidal sectors manufactured at factory, and assembled on-site; seven of the 40-degree sectors, two of the 30-degree beside final one, and the final of the 20-degree. The final sector is assembled with the VV thermal shield and toroidal field magnets into the 340-degree as prepared in one sector. Sectors are temporally fitted on-site and adjusted one over the other before the assembly. After measurement of the dimensions and the reference, these sectors are transferred onto the cryostat base. First, three 80-degree sectors are manufactured with mating each 40-degree sector by direct joint welding. The rest sectors including the final sector are jointed with splice plates. Welding manipulator and its guide rails are used for these welding. In this paper, the detail of the VV sectors assembly including the final sector is explained. Welding technologies to joint the two of 40-degree sectors are reported with the present manufacturing status and the welding trial on the vertical stub with the partial mock-up of the final sector are discussed with the assembly process.

Journal Articles

Characterization of LiNbO$$_3$$ single-crystal substrates irradiated with electrons

Miyazaki, Hisashi*; Morimoto, Jun*; Toda, Koji*; Onoda, Shinobu; Oshima, Takeshi

Japanese Journal of Applied Physics, 50(7), p.07HB07_1 - 07HB07_4, 2011/07

 Times Cited Count:0 Percentile:0(Physics, Applied)

Journal Articles

Raman and FT-IR spectroscopy of electron irradiated LiNbO$$_3$$

Miyazaki, Hisashi*; Morimoto, Jun*; Toda, Koji*; Onoda, Shinobu; Oshima, Takeshi

Proceedings of 9th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-9), p.226 - 229, 2010/10

Journal Articles

Ion-irradiation effects of hydrogen absorption in palladium metal

Yoneda, Yasuhiro; Tamura, Kazuhisa; Abe, Hiroshi; Oshima, Takeshi; Morimoto, Ryo*; Uchida, Hirohisa*; Mizuki, Junichiro

Transactions of the Materials Research Society of Japan, 33(4), p.1053 - 1056, 2008/12

The effect of ion irradiation on palladium (Pd) metal was investigated by hydrogen-absorption measurements, SEM microscopy and synchrotron X-ray diffraction. N$$^+$$ irradiation was made with an acceleration energy 350 keV. The initial hydrogen absorption rate of the irradiated Pd was three times larger than that of non-irradiated Pd. The microscopic structure was investigated by using the pair-distribution function (PDF) obtained by X-ray diffraction. Although the average structure of the Pd was f.c.c, the Pd atoms displaced and two occupancy sites are revealed. This site occupancy is closely related with the hydrogen-absorption rate.

Journal Articles

Simultaneous measurements of ion and electron currents using a novel compact electrostatic end-loss-current detector

Hirata, Mafumi*; Miyake, Yasuhiro*; Chujo, T.*; Kohagura, Junko*; Numakura, Tomoharu*; Shimizu, Kiyoaki*; Ito, Marie*; Kiminami, Serina*; Morimoto, Naomichi*; Hirai, Katsuaki*; et al.

Review of Scientific Instruments, 77(10), p.10E719_1 - 10E719_3, 2006/10

 Times Cited Count:0 Percentile:0.01(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Hydrogen retention in divertor tiles used in JT-60 for hydrogen discharge period

Hirohata, Yuko*; Shibahara, Takahiro*; Tanabe, Tetsuo*; Arai, Takashi; Goto, Yoshitaka*; Oya, Yasuhisa*; Yoshida, Hajime*; Morimoto, Yasutomi*; Yagyu, Junichi; Masaki, Kei; et al.

Journal of Nuclear Materials, 337-339, p.609 - 613, 2005/03

 Times Cited Count:13 Percentile:68.06(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

ITER nuclear components, preparing for the construction and R&D results

Ioki, Kimihiro*; Akiba, Masato; Barabaschi, P.*; Barabash, V.*; Chiocchio, S.*; Daenner, W.*; Elio, F.*; Enoeda, Mikio; Ezato, Koichiro; Federici, G.*; et al.

Journal of Nuclear Materials, 329-333(1), p.31 - 38, 2004/08

 Times Cited Count:13 Percentile:66.18(Materials Science, Multidisciplinary)

The preparation of the procurement specifications is being progressed for key components. Progress has been made in the preparation of the procurement specifications for key nuclear components of ITER. Detailed design of the vacuum vessel (VV) and in-vessel components is being performed to consider fabrication methods and non-destructive tests (NDT). R&D activities are being carried out on vacuum vessel UT inspection with waves launched at an angle of 20 or 30 degree, on flow distribution tests of a two-channel model, on fabrication and testing of FW mockups and panels, on the blanket flexible support as a complete system including the housing, on the blanket co-axial pipe connection with guard vacuum for leak detection, and on divertor vertical target prototypes. The results give confidence in the validity of the design and identify possibilities of attractive alternate fabrication methods.

Journal Articles

Analyses of hydrogen isotope distributions in the outer target tile used in the W-shaped divertor of JT-60U

Oya, Yasuhisa*; Morimoto, Yasutomi*; Oyaizu, Makoto*; Hirohata, Yuko*; Yagyu, Junichi; Miyo, Yasuhiko; Goto, Yoshitaka*; Sugiyama, Kazuyoshi*; Okuno, Kenji*; Miya, Naoyuki; et al.

Physica Scripta, T108, p.57 - 62, 2004/00

no abstracts in English

Journal Articles

Shutdown dose evaluation experiment for ITER

Morimoto, Yuichi*; Ochiai, Kentaro; Sato, Satoshi; Hori, Junichi; Yamauchi, Michinori*; Nishitani, Takeo

Fusion Engineering and Design, 69(1-4), p.643 - 648, 2003/09

 Times Cited Count:3 Percentile:26.72(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Neutronics experiments for DEMO blanket at JAERI/FNS

Sato, Satoshi; Ochiai, Kentaro; Hori, Junichi; Verzilov, Y. M.; Klix, A.; Wada, Masayuki*; Terada, Yasuaki*; Yamauchi, Michinori*; Morimoto, Yuichi*; Nishitani, Takeo

Nuclear Fusion, 43(7), p.527 - 530, 2003/07

 Times Cited Count:15 Percentile:46.44(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Hydrogen isotope behavior in in-vessel components used for DD plasma operation of JT-60U by SIMS and XPS technique

Oya, Yasuhisa*; Hirohata, Yuko*; Morimoto, Yasutomi*; Yoshida, Hajime*; Kodama, Hiroshi*; Kizu, Kaname; Yagyu, Junichi; Goto, Yoshitaka*; Masaki, Kei; Okuno, Kenji*; et al.

Journal of Nuclear Materials, 313-316, p.209 - 213, 2003/03

 Times Cited Count:25 Percentile:84.36(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Development of in-vessel neutron monitor using micro-fission chambers for ITER

Yamauchi, Michinori*; Nishitani, Takeo; Ochiai, Kentaro; Morimoto, Yuichi*; Hori, Junichi; Ebisawa, Katsuyuki*; Kasai, Satoshi; Walker, C.*

Review of Scientific Instruments, 74(3), p.1730 - 1734, 2003/03

 Times Cited Count:21 Percentile:71.21(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Analysis technology of nuclear fusion materials by XPS

Yagyu, Junichi; Goto, Yoshitaka*; Arai, Takashi; Miya, Naoyuki; Morimoto, Yasutomi*; Okuno, Kenji*; Oya, Yasuhisa*; Hirohata, Yuko*; Tanabe, Tetsuo*

Heisei-15-Nendo Kiki, Bunseki Gijutsu Kenkyukai Hokoku, p.105 - 108, 2003/00

no abstracts in English

Journal Articles

Radioactivity production around the surface of a cooling water pipe in a D-T fusion reactor by sequential charged particle reactions

Hori, Junichi; Maekawa, Fujio; Wada, Masayuki*; Ochiai, Kentaro; Yamauchi, Michinori*; Morimoto, Yuichi*; Terada, Yasuaki; Klix, A.; Nishitani, Takeo

Fusion Engineering and Design, 63-64, p.271 - 276, 2002/12

 Times Cited Count:2 Percentile:17.59(Nuclear Science & Technology)

In order to the waste management method and the safety design of future D-T fusion reactor, it is important to consider the radioactivity productions via not only primary neutron reactions but also sequential charged particle reactions (SCPR). Especially, on the surface of a coolant channel many recoiled protons are generated by the neutron irradiation with coolant water, so it is apprehensive that the undesirable radioactive nuclide production yields via SCPR are enhanced. In this work, the laminated sample pieces of fusion material foils (V, Fe, W, Ti, Pb, Cu) were made and attached on a polyethylene board to simulate water flowing inside a coolant channel. They were irradiated with D-T neutrons. The effective radioactivity cross section and the depth distribution of the radioactivity production yields due to SCPR were obtained for each material. On the other hand, the estimated values were compared with the experimental ones.

Journal Articles

Neutronics experiment of $$^{6}$$Li-enriched breeding blanket with Li$$_{2}$$TiO$$_{3}$$/Be/F82H assembly using D-T neutrons

Ochiai, Kentaro; Klix, A.; Hori, Junichi; Morimoto, Yuichi*; Wada, Masayuki*; Nishitani, Takeo

Journal of Nuclear Science and Technology, 39(Suppl.2), p.1147 - 1150, 2002/08

Thermal blanket type as one of conceptual designs for DEMO-fusion blanket is proposed. We have irradiated the trial blanket assembly which was stratified 95-% enriched Li2TiO3,F82H and beryllium block using Fusion Neutron Source (FNS) and verified the accuracy of these parameters by measurements of tritium and gamma-ray emitted from samples of95-% enriched Li2TiO3 and F82H. We have used the liquid scintillated counter as the method of tritium measurement. Activation foils, NE213, Si-SBD and Fission chamber have usedto measure neutron fluence. Moreover, we have concurrently measured the gamma rays of 56Mn, 54Mn, 187W and 51Cr was produced by 56Fe(n,p), 54Fe(n,p), 186W(n,g), 52Cr(n,2n) and 50Cr(n,g) in F82H. We have used the JENDL Fusion File library and MCNP to verify the accuracy tritium-production rate and 56Mn, 54Mn, 187W and 51Cr. From the results of above experiments, MCNP that uses the JENDL-FF nuclear data library can predict the nuclear parameters such as TPR, Nb, 56Mn, In and 54Mn in the test assemblies within an accuracy of 10%.

Journal Articles

Tritium measurements for $$^{6}$$Li-enriched Li$$_{2}$$TiO$$_{3}$$ breeding blanket experiments with D-T neutrons

Klix, A.; Ochiai, Kentaro; Terada, Yasuaki; Morimoto, Yuichi*; Yamauchi, Michinori*; Hori, Junichi; Nishitani, Takeo

Fusion Science and Technology, 41(3, Part2), p.1040 - 1043, 2002/05

$$^{6}$$Li-enriched Li$$_{2}$$TiO$$_{3}$$ is one of the candidate materials for the breeding blanket of the fusion DEMO reactor. Therefore, it is necessary to measure the tritium production performance and estimate the accuracy of the measurement method. The JAERI Fusion Neutronics Source (FNS) group has carried out experiments with breeding blanket mock-ups composed of layers of beryllium, ferritic steel F82H and enriched Li$$_{2}$$TiO$$_{3}$$. Pellets of enriched Li$$_{2}$$TiO$$_{3}$$ with a diameter of 12mm and a thickness of 2mm were used as detectors inside the tritium breeding layer. After irradiation, the pellets were dissolved and the tritium activity in the sample solution was measured by liquid scintillation counting. The experimentally obtained tritium production profile in the lithium titanate layer agreed well with MCNP calculations within the estimated error of the measured values (10%). The calculation-experiment ratio was close to one for all samples. Tritium loss from the pellet during storage time (a few days) was experimentally found to be negligible.

JAEA Reports

Performance test of micro-fission chambers for in-vessel neutron monitoring of ITER

Yamauchi, Michinori*; Nishitani, Takeo; Ochiai, Kentaro; Morimoto, Yuichi*; Hori, Junichi; Ebisawa, Katsuyuki*; Kasai, Satoshi

JAERI-Tech 2002-032, 41 Pages, 2002/03

JAERI-Tech-2002-032.pdf:2.62MB

A micro-fission chamber and a dummy chamber without uranium were fabricated and the performance was tested. They are designed to be installed inside the vacuum vessel of compact ITER (ITER-FEAT) for neutron monitoring. Vacuum leak rate of the chamber, resistances between central conductor and outer sheath, and mechanical strength up to 50G acceleration were confirmed to meet design criteria. Gamma-ray sensitivity was measured with $$^{60}$$Co gamma-ray irradiation facility at JAERI Takasaki. The output signals for gamma-rays in Campbelling mode were estimated to be less than 0.1% those by neutrons at the location behind the blanket module in ITER-FEAT. Detector response for 14 MeV neutrons was investigated with the FNS facility. Excellent linearity between count rates and neutron fluxes was confirmed. According to the test for the change of surrounding materials, the sensitivity was enhanced by slow-downed neutrons, which agreed with the calculation result by MCNP-4C code. As a result, it was concluded that the developed micro-fission chamber is applicable for ITER-FEAT.

33 (Records 1-20 displayed on this page)