Improvement of thermal insulation materials for the expansion joint of the steam plumbing for Reprocessing Plants

Komatsu, Seiji; Nishida, Tetsuro; Kawasaki, Ichio; Gunji, Hikaru; Nishino, Shohei; Kambara, Takashi*; Miura, Hirohito*; Suzuki, Takaichi*; Kinoshita, Masato*; Kanei, Tatsuya*

Nihon Hozen Gakkai Dai-21-Kai Gakujutsu Koenkai Yoshishu, 5 Pages, 2025/07

Steam used for process and air conditioning in each facility at the Nuclear Fuel Cycle Engineering Institute is generated by a water tube boiler installed in the Institute's central control room and supplied to each facility via underground trenches. There are three steam supply pipelines (A, B, and C) to each facility, with two of these (A and B) designated for the reprocessing facility. The steam pipelines, including expansion joints and steam traps, are covered with insulation. The two steam pipelines for the reprocessing facility (A and B) are laid parallel, creating a structure that makes inspection and maintenance difficult. In particular, the expansion joints are spaced very closely between the A and B lines, making insulation removal difficult, which has been a challenge in performing visual inspections of the expansion joint bodies. This paper reports on the features and effects of an improved insulation system designed to allow for easy removal and installation.

Growth processes of zircon crystals in a granitic magma chamber, variation in U-Pb age, titanium concentration, and Th/U in relation to internal texture

Yuguchi, Takashi*; Endo, Kyoka*; Suzuki, Satoshi*; Ogita, Yasuhiro; Sakata, Shuhei*; Yokoyama, Tatsunori; Imura, Takumi*; Ono, Takeshi*; Sasao, Eiji

Lithos, 494-495, p.107909_1 - 107909_14, 2025/02

https://doi.org/10.1016/j.lithos.2024.107909

This study described the growth characteristics of zircon crystals in the Kuki granite from the Kitakami Mountains in northeastern Japan as the key for elucidating granitic magma chamber processes. Using two approaches, analyses based on multiple sections of separated zircon crystals and thin-section-based zircon crystal analyses, we determined the characteristics of the 3D internal structure of the crystals, variations in U-Pb age, Ti concentrations, and Th/U in relation to crystal texture, and the crystallization sequence between zircon crystals and other minerals within the magma chamber. The textures, which occupy a large proportion of zircon, comprise low luminescence homogeneous cores (LLCs) and oscillatory zoning (OZ). The 3D distribution of the zircon internal structure can be classified into three types: Type 1 zircon comprising LLCs and the surrounding OZ and Types 2 and 3 zircon crystals composed entirely of OZ from the cores to the rims and characterized by brightness and darkness cores, respectively. LLC and OZ grew at temperatures from approximately 900 to 800C and 850 to 700C, respectively, and LLC has a higher Th/U than that of OZ, indicating that fractional crystallization progression as the magma chamber cooled resulted in the transition from LLC to OZ. In the progression of fractional crystallization, the diffusion rate deceleration with decreasing magma temperatures triggered the transition from interfacial reaction-controlled growth producing LLC to diffusion-controlled growth producing OZ. In the thin-section analysis, zircon crystals which contained in different minerals are characterized by different Th/U values. The variation in Th/U and the crystallization temperature of zircon crystals considering the surrounding minerals can be used to elucidate the differentiation and mineral crystallization in magma chamber processes over a wide range of temperature conditions.

Characterization of nitrided SiC(100) MOS structures by means of electrical measurements and X-ray photoelectron spectroscopy

Kobayashi, Takuma*; Suzuki, Asato*; Nakanuma, Takato*; Sometani, Mitsuru*; Okamoto, Mitsuo*; Yoshigoe, Akitaka; Shimura, Takayoshi*; Watanabe, Heiji*

Materials Science in Semiconductor Processing, 175, p.108251_1 - 108251_7, 2024/06

https://doi.org/10.1016/j.mssp.2024.108251

Deuterium content and site occupancy in iron sulfide at high pressure and temperature determined using in situ neutron diffraction measurements

Abeykoon, S.*; Howard, C.*; Dominijanni, S.*; Eberhard, L.*; Kurnosov, A.*; Frost, D. J.*; Boffa Ballaran, T.*; Terasaki, Hidenori*; Sakamaki, Tatsuya*; Suzuki, Akio*; et al.

Journal of Geophysical Research; Solid Earth, 128(9), p.e2023JB026710_1 - e2023JB026710_17, 2023/09

https://doi.org/10.1029/2023JB026710

Small amounts of iron sulphide minerals are found in most rocks from the Earth's mantle and as inclusions trapped in natural diamonds. Hydrogen may dissolve into iron sulphide minerals under high pressures and temperature, but is most likely lost once pressure and temperature are removed. In this study, we determined deuterium contents in iron sulphide, held under high pressure and temperature conditions, using neutron diffraction measurements with 6-ram multi-anvil press at PLANET, J-PARC. Deuterium contents in iron sulphide were measured at high-P, up to 11.4 GPa and high-T to 1300 K in in situ neutron diffraction experiments. The total deuterium content increases with both P and T. The results are used to estimate hydrogen contents of iron sulphide minerals in the deep continental lithospheric mantle, which are found to be in the range 1700-2700 ppm. This corresponds to approximately 2-3 ppm of hydrogen in the bulk mantle.

Database for corrosion under irradiation

Sato, Tomonori; Hata, Kuniki; Kaji, Yoshiyuki; Taguchi, Mitsumasa*; Seito, Hajime*; Inoue, Hiroyuki*; Tada, Eiji*; Abe, Hiroshi*; Akiyama, Eiji*; Suzuki, Shunichi*

Isotope News, (782), p.40 - 44, 2022/08

https://www.jrias.or.jp/pdf/2208_TRACER_SATO_HOKA.pdf

The stagnant water in the reactor building at Fukushima Daiichi Nuclear Power Station (1F) is exposed to the radiation from fuel debris and radioactive species. This water contains much amounts of impurities from the seawater which was injected in the emergency cooling. The impurities will affect the radiolysis and corrosive conditions in the water under irradiation. So, the water radiolysis data, corrosion data of steels under irradiations, and the evaluated potential impacts of corrosion in the decommissioning process of 1F are arranged as the database for corrosion under irradiation. This paper introduces the outline of this database.

Database for corrosion under irradiation conditions (Contract research)

Sato, Tomonori; Hata, Kuniki; Kaji, Yoshiyuki; Ueno, Fumiyoshi; Inoue, Hiroyuki*; Taguchi, Mitsumasa*; Seito, Hajime*; Tada, Eiji*; Abe, Hiroshi*; Akiyama, Eiji*; et al.

JAEA-Review 2021-001, 123 Pages, 2021/06

JAEA-Review-2021-001.pdf:10.33MB

In the implement of the decommissioning of Fukushima Daiichi Nuclear Power Station (1F), there are many problems to be solved. Specially, the mitigation of the aging degradation by the corrosion of the structural materials is important to implement the decommissioning safely and continuously. However, there are limited data for the environmental factors of corrosion in 1F, and the condition of 1F is continuously changing. So, the literature data for the water radiolysis and the corrosion under irradiation are listed as the database of corrosion under irradiation in this report. And the new obtained radiolysis and corrosion data, which have not been reported in the literature and will be required in the decommissioning of 1F, are reported.

High-spin states in S

Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.

Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03

https://doi.org/10.1103/PhysRevC.103.034327

Interfacial ferromagnetism and atomic structures in high-temperature grown FeO/Pt/FeO epitaxial trilayers

Kikkawa, Takashi*; Suzuki, Motohiro*; Ramos, R.*; Aguirre, M. H.*; Okabayashi, Jun*; Uchida, Kenichi*; Lucas, I.*; Anadn, A.*; Kikuchi, Daisuke*; Algarabel, P. A.*; et al.

Journal of Applied Physics, 126(14), p.143903_1 - 143903_11, 2019/10

https://doi.org/10.1063/1.5125761

Development of a crack opening displacement assessment procedure considering change of compliance at a crack part in thin wall pipes made of modified 9Cr-1Mo steel

Wakai, Takashi; Machida, Hideo*; Arakawa, Manabu*; Yanagihara, Seiji*; Suzuki, Ryosuke*; Matsubara, Masaaki*

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 9 Pages, 2018/07

This paper studies crack opening displacement (COD) evaluation methods used in Leak-Before-Break (LBB) assessment of Sodium cooled Fast Reactor (SFR) pipe. For SFR pipe, the continuous leak monitoring will be adopted as an alternative to a volumetric test of the weld joints under conditions that satisfy LBB. The sodium pipes are made of ASME Gr.91 (modified 9Cr-1Mo steel). Thickness of the pipes is small, because the internal pressure is very small. Modified 9Cr-1Mo steel has a relatively large yield stress and small work hardening coefficient comparing to the austenitic stainless steels which are currently used in the conventional plants. In order to assess the LBB behavior of the sodium pipes made of modified 9Cr-1Mo steel, the coolant leak rate from a through wall crack must be estimated properly. Since the leak rate is strongly related to the crack opening displacement (COD), an appropriate COD assessment method must be established to perform LBB assessment. However, COD assessment method applicable for SFR pipes - having thin wall thickness and made of small work hardening material - has not been proposed yet. Thus, a COD assessment method applicable to such a pipe was proposed in this study. In this method, COD was calculated by classifying the components of COD; elastic, local plastic and fully plastic. In addition, the verification of this method was performed by comparing with the results of a series of four-point bending tests using modified 9Cr-1Mo steel pipe having a circumferential through wall notch. As a result, in some cases, COD were over-estimated especially for large cracks. Although the elastic component of COD is still over-estimated for large cracks, leak evaluation from small cracks is much more important in LBB assessment. Therefore, this study recommends that only the elastic component of COD should be adopted in LBB assessment of SFR pipes.

Design of HTTR-GT/H test plant

Yan, X.; Sato, Hiroyuki; Sumita, Junya; Nomoto, Yasunobu*; Horii, Shoichi*; Imai, Yoshiyuki; Kasahara, Seiji; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; et al.

Nuclear Engineering and Design, 329, p.223 - 233, 2018/04

https://doi.org/10.1016/j.nucengdes.2017.10.009

The pre-licensing design of an HTGR cogeneration test plant to be coupled to JAEA's existing test reactor HTTR is presented. The plant is designed to demonstrate the system of JAEA commercial plant design GTHTR300C. With construction planned to be completed around 2025, the test plant is expected to be the first-of-a-kind nuclear system operating on two of the advanced energy conversion systems attractive for the HTGR closed cycle helium gas turbine for power generation and thermochemical iodine-sulfur water-splitting process for hydrogen production.