Phase analysis of simulated nuclear fuel debris synthesized using UO, Zr, and stainless steel and leaching behavior of the fission products and matrix elements

Tonna, Ryutaro*; Sasaki, Takayuki*; Kodama, Yuji*; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Kumagai, Yuta; Kusaka, Ryoji; Watanabe, Masayuki

Nuclear Engineering and Technology, 55(4), p.1300 - 1309, 2023/04

https://doi.org/10.1016/j.net.2022.12.017

Simulated debris was synthesized using UO, Zr, and stainless steel and a heat treatment method under inert or oxidizing conditions. The primary U solid phase of the debris synthesized at 1473 K under inert conditions was UO, whereas a (U,Zr)O solid solution formed at 1873 K. Under oxidizing conditions, a mixture of UO and (Fe,Cr)UO phases formed at 1473 K whereas a (U,Zr)O solid solution formed at 1873 K. The leaching behavior of the fission products from the simulated debris was evaluated using two methods: the irradiation method, for which fission products were produced via neutron irradiation, and the doping method, for which trace amounts of non-radioactive elements were doped into the debris. The dissolution behavior of U depended on the properties of the debris and aqueous medium the debris was immersed in. Cs, Sr, and Ba leached out regardless of the primary solid phases. The leaching of high-valence Eu and Ru ions was suppressed, possibly owing to their solid-solution reaction with or incorporation into the uranium compounds of the simulated debris.

The Chemistry of thorium, plutonium and MA

Sato, Nobuaki*; Kirishima, Akira*; Watanabe, Masayuki; Sasaki, Takayuki*; Uehara, Akihiro*; Takeda, Shino*; Kitatsuji, Yoshihiro; Otobe, Haruyoshi; Kobayashi, Taishi*

The Chemistry of Thorium, Plutonium and MA, 254 Pages, 2022/03

The chemistry of nuclear materials such as Thorium (Part 1) and Plutonium (Part 2) was described in relation from the fundamentals on solid chemistry and solution chemistry to the practicals on the experiment and evaluation method in detail. Minor actinides such as Neptunium, Americium, Curium and Protoactinium, was introduced the basics on the solid and solution chemistry.

Local structure study of the iron-based systems of BaFeAs and LiFeAs by X-ray PDF and XAFS analyses

Li, S.*; Toyoda, Masayuki*; Kobayashi, Yoshiaki*; Ito, Masayuki*; Ikeuchi, Kazuhiko*; Yoneda, Yasuhiro; Otani, Akira*; Matsumura, Daiju; Asano, Shun*; Mizuki, Junichiro*; et al.

Physica C, 555, p.45 - 53, 2018/12

https://doi.org/10.1016/j.physc.2018.10.003

-dependence of local distortions in BaFeAs and LiFeAs by X-ray PDF and XAFS methods. Although PDF data exhibit anomaly at the structure transition temperature, EXAFS data exhibit no anomaly. Data supporting the local orthorhombicity at 300 K in the tetragonal phase for BaFeAs. Arguments on the origins of the 4-fold symmetry breaking in the ground average structure of the tetragonal phase.

Ni synchrotron radiation-based Mssbauer spectroscopy of nickel-based nanoparticles with hexagonal structure

Masuda, Ryo*; Kobayashi, Yasuhiro*; Kitao, Shinji*; Kurokuzu, Masayuki*; Saito, Makina*; Yoda, Yoshitaka*; Mitsui, Takaya; Hosoi, Kohei*; Kobayashi, Hirokazu*; Kitagawa, Hiroshi*; et al.

Scientific Reports (Internet), 6, p.20861_1 - 20861_8, 2016/02

https://doi.org/10.1038/srep20861

Progress and status of the gyrotron development for the JT-60SA ECH/CD system

Kobayashi, Takayuki; Sawahata, Masayuki; Terakado, Masayuki; Hiranai, Shinichi; Ikeda, Ryosuke; Oda, Yasuhisa; Wada, Kenji; Hinata, Jun; Yokokura, Kenji; Hoshino, Katsumichi; et al.

Proceedings of 40th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2015) (USB Flash Drive), 3 Pages, 2015/08

A gyrotron for electron cyclotron heating and current drive (ECH/CD) has been developed for JT-60SA (Super-Advanced). In high-power, long-pulse operations, oscillations of 1 MW/100 s have been demonstrated at both 110 GHz and 138 GHz, for the first time. These results fully satisfied the requirements for JT-60SA. Moreover, it was experimentally shown that the higher power operation at each frequency is expected to be acceptable for this gyrotron from the viewpoint of heat load at the cavity resonator, collector, and stray radiation absorbers. An oscillation at 82 GHz, which is an additional frequency, has been demonstrated up to 2 s at the output power of 0.4 MW, so far. High power experiments toward higher power of 1.5 MW (110/138 GHz) and 1 MW (82 GHz) are ongoing.

Development of a dual frequency (110/138 GHz) gyrotron for JT-60SA and its extension to an oscillation at 82 GHz

Kobayashi, Takayuki; Moriyama, Shinichi; Isayama, Akihiko; Sawahata, Masayuki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; et al.

EPJ Web of Conferences, 87, p.04008_1 - 04008_5, 2015/03

https://doi.org/10.1051/epjconf/20158704008

A dual-frequency gyrotron, which can generate 110 GHz and 138 GHz waves independently, is being developed in JAEA to enable electron cyclotron heating (ECH) and current drive (ECCD) in a wider range of plasma discharge conditions of JT-60SA. Operation for the gyrotron conditioning and parameter optimization toward 1 MW for 100 s, which is the target output power and pulse length for JT-60SA, is in progress without problems. Oscillations of 1 MW for 10 s and 0.51 MW for 198 s were obtained, so far, at both frequencies. In addition, an oscillation (0.3 MW for 20 ms) at 82 GHz was demonstrated as an additional frequency of the dual-frequency gyrotron which shows a possibility of the use of fundamental harmonic wave in JT-60SA.

Stratigraphy and AMS radiocarbon dates of cored sediments (IrBH-2) from the Irosin Caldera, the Philippines

Mirabueno, M. H. T.*; Torii, Masayuki*; Laguerta, E. P.*; Delos Reyes, P. J.*; Fujiki, Toshiyuki*; Bariso, E. B.*; Okuno, Mitsuru*; Nakamura, Toshio*; Danhara, Toru*; Kokubu, Yoko; et al.

Chigaku Zasshi, 123(5), p.751 - 760, 2014/10

https://doi.org/10.5026/jgeography.123.751

Core drilling at site IRBH-2 within Irosin caldera, southern Luzon, reached 50 m. Systematic logging and documentation were done to describe the sediments. AMS C dates were obtained for plant fragments from the peaty layers. Lahars and fluvial deposits were the predominant deposits in the core sequence. The upper 12 m was comprised mostly by andesitic fluvial and minor lahars. Eight fallouts were intercalated with reworked sediments from depth interval of 20 to 50 m. The refractive index measurement of analyzed samples indicated that post-caldera eruptions generated andesite, dacite and minor rhyolite. The similarity in petrographic characteristics between the rhyolite fallout and the Irosin ignimbrite indicates that small-scale eruptions involving magma from the caldera event occurred during post-caldera stage.Young radiocarbon dates obtained from the peaty layers shows that volcaniclastic deposits in the upper levels were likely derived from the eruptions of Bulusan volcano.

Development of extraction chromatographic adsorbent using alkylpyridinedicarboxyamides as extractant for separation of trivalent minor actinides from lanthanides; Stability and separation ability against nitric acid exposure and -ray irradiation

Arisaka, Makoto; Watanabe, Masayuki; Sugo, Yumi; Kobayashi, Kumiko*; Kanao, Osamu*; Kimura, Takaumi

Journal of Nuclear Science and Technology, 51(4), p.457 - 464, 2014/04

https://doi.org/10.1080/00223131.2014.874301

Toward the development of a practical separation method for trivalent actinides and lanthanides, we used extraction chromatography with alkyl-pyridinedicarboxyamides as the extractant. The results confirmed that the performance degradation of the adsorbent caused by contact with HNO and/or irradiation with rays would be very small during the operation of column chromatography. The optimal conditions for the column separation were also determined: eluent, 5M HNO; flow rate, 0.1 mL/min.

Development of instrument to measure transmission power density distribution using dielectric disk in millimeter waveguide

Yokokura, Kenji; Moriyama, Shinichi; Kobayashi, Takayuki; Hiranai, Shinichi; Sawahata, Masayuki; Terakado, Masayuki; Hinata, Jun; Wada, Kenji; Sato, Yoshikatsu; Hoshino, Katsumichi; et al.

JAEA-Technology 2014-002, 64 Pages, 2014/03

JAEA-Technology-2014-002.pdf:6.83MB

A new instrument has been developed to measure spatial distribution of power density and total power of the millimeter wave, by measuring temperature rise of dielectric material inserted in the waveguide. For a measurement, a dielectric disk with thermally insulated support is inserted into the few millimeters gap in the waveguide. The disk is heated by the millimeter wave pulse for 0.10.2 s, and immediately after the pulse, it is pulled up and its temperature distribution is measured by an infrared camera to estimate the spatial power density distribution of the millimeter wave. In the other hand, total transmission power is estimated by the disk temperature reached equilibrium. In the measurement test, deformation of the power density distribution was successfully detected when the mirror angle was intentionally changed in the matching optics unit (MOU) at the waveguide input from the gyrotron. The test result shows that the instrument is effective for both adjustment of MOU without opening the vacuum boundary and to detect any abnormal transmission during operation of the ECH system. The test also shows high reliability of the instrument which stands with 1 MW high power transmission without any arcing or pressure rise in vacuum region. The instrument will be contributed to keep good condition of high power long pulse ECH system by detecting abnormal transmission in the waveguide in operation without open vacuum boundary.

Development of a linear motion antenna for the JT-60SA ECRF system

Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Hoshino, Katsumichi; Suzuki, Sadaaki; Hiranai, Shinichi; Yokokura, Kenji; Sawahata, Masayuki; Terakado, Masayuki; Hinata, Jun; et al.

Fusion Engineering and Design, 88(6-8), p.935 - 939, 2013/10

https://doi.org/10.1016/j.fusengdes.2013.02.019

An antenna having a first mirror driven in the linear motion (LM) and a fixed second mirror was proposed for electron cyclotron range of frequency (ECRF) heating and current drive system, to minimize the risk of cooling-water-leakage. Basic mechanical feasibilities of the bellows covering the movable structures of the antenna were previously investigated using a mock-up. This time, a support structure of the shaft has been designed using a metallic sliding bearing with solid lubricant. The sliding bearing can support combination of linear and rotational motions while a ball bearing supports either linear or rotational motion. We have newly installed the sliding bearing into the mock-up. A vacuum pumping test has been carried out paying attention to the influence of the solid lubricant by mass analysis. To design the LM antenna for JT-60SA in detail, heating and current drive characteristics for typical experimental scenarios of JT-60SA has been investigated by calculation.