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Journal Articles

Slow electronic dynamics in the paramagnetic state of UTe$$_2$$

Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Haga, Yoshinori; Tokiwa, Yoshifumi; Opletal, P.; Fujibayashi, Hiroyuki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; et al.

Journal of the Physical Society of Japan, 91(2), p.023707_1 - 023707_5, 2022/02

$$^{125}$$Te NMR experiments in field ($$H$$) applied along the easy magnetization axis (the $$a$$-axis) revealed slow electronic dynamics developing in the paramagnetic state of UTe$$_2$$. The observed slow fluctuations are concerned with a successive growth of long-range electronic correlations below 30$$-$$40 K, where the spin susceptibility along the hard magnetization axis (the $$b$$-axis) shows a broad maximum. The experiments also imply that tiny amounts of disorder or defects locally disturb the long-range electronic correlations and develop an inhomogeneous electronic state at low temperatures, leading to a low temperature upturn observed in the bulk-susceptibility in $$H|a$$. We suggest that UTe$$_2$$ would be located on the paramagnetic side near an electronic phase boundary, where either the magnetic or Fermi-surface instability would be the origin of the characteristic fluctuations.

Journal Articles

Analytical study on dynamic response of reinforced concrete structure with internal equipment subjected to projectile impact

Okuda, Yukihiko; Kang, Z.; Nishida, Akemi; Tsubota, Haruji; Li, Y.

Doboku Gakkai Dai-13-Kai Kozobutsu No Shogeki Mondai Ni Kansuru Shinpojiumu Rombunshu (Internet), 8 Pages, 2022/01

In case missiles crash into reactor buildings of nuclear power plants, stress waves due to the missile impacts propagate from the impacted wall to the interior of the structure. Stress waves are likely to excite high-frequency vibrations of internal equipment in the reactor building, so it is an important issue to assess the damage against missile impact for safety related internal equipment. The OECD/NEA launched the IRIS benchmark project in order to assess the response for nuclear facility by projectile impact and the third phase of IRIS (IRIS 3) contributes to the investigation on the dynamic response of reinforced concrete (RC) structure with internal equipment. We participated in the IRIS3 and have conducted the calibration analysis for projectile impact test of the structure which models a reactor building and internal equipment. This paper presents simulation and test results from dynamic response of the RC structure with internal equipment.

JAEA Reports

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2020

Nakano, Masanao; Nakada, Akira; Kanai, Katsuta; Nagaoka, Mika; Koike, Yuko; Yamada, Ryohei; Kubota, Tomohiro; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; et al.

JAEA-Review 2021-040, 118 Pages, 2021/12

JAEA-Review-2021-040.pdf:2.48MB

Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2020. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.

Journal Articles

Comparison of dose rates from four surveys around the Fukushima Daiichi Nuclear Power Plant for location factor evaluation

Sanada, Yukihisa; Ishida, Mutsushi*; Yoshimura, Kazuya; Mikami, Satoshi

Journal of Radiation Protection and Research, 46(4), p.184 - 193, 2021/12

no abstracts in English

Journal Articles

Hybridization of Bogoliubov quasiparticles between adjacent CuO$$_2$$ layers in the triple-layer cuprate Bi$$_2$$Sr$$_2$$Ca$$_2$$Cu$$_3$$O$$_{10+delta}$$ studied by angle-resolved photoemission spectroscopy

Ideta, Shinichiro*; Johnston, S.*; Yoshida, Teppei*; Tanaka, Kiyohisa*; Mori, Michiyasu; Anzai, Hiroaki*; Ino, Akihiro*; Arita, Masashi*; Namatame, Hirofumi*; Taniguchi, Masaki*; et al.

Physical Review Letters, 127(21), p.217004_1 - 217004_6, 2021/11

Journal Articles

Design for detecting recycling muon after muon-catalyzed fusion reaction in solid hydrogen isotope target

Okutsu, Kenichi*; Yamashita, Takuma*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.

Fusion Engineering and Design, 170, p.112712_1 - 112712_4, 2021/09

A muonic molecule which consists of two hydrogen isotope nuclei (deuteron (d) or tritium (t)) and a muon decays immediately via nuclear fusion and the muon will be released as a recycling muon, and start to find another hydrogen isotope nucleus. The reaction cycle continues until the muon ends up its lifetime of 2.2 $$mu$$s. Since the muon does not participate in the nuclear reaction, the reaction is so called a muon catalyzed fusion ($$mu$$CF). The recycling muon has a particular kinetic energy (KE) of the muon molecular orbital when the nuclear reaction occurs. Since the KE is based on the unified atom limit where distance between two nuclei is zero. A precise few-body calculation estimating KE distribution (KED) is also in progress, which could be compared with the experimental results. In the present work, we observed recycling muons after $$mu$$CF reaction.

Journal Articles

Time evolution calculation of muon catalysed fusion; Emission of recycling muons from a two-layer hydrogen film

Yamashita, Takuma*; Okutsu, Kenichi*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.

Fusion Engineering and Design, 169, p.112580_1 - 112580_5, 2021/08

A muon ($$mu$$) having 207 times larger mass of electron and the same charge as the electron has been known to catalyze a nuclear fusion between deuteron (d) and triton (t). These two nuclei are bound by $$mu$$ and form a muonic hydrogen molecular ion, dt$$mu$$. Due to the short inter-nuclear distance of dt$$mu$$, the nuclear fusion, d +t$$rightarrow alpha$$ + n + 17.6 MeV, occurs inside the molecule. This reaction is called muon catalyzed fusion ($$mu$$CF). Recently, the interest on $$mu$$CF is renewed from the viewpoint of applications, such as a source of high-resolution muon beam and mono-energetic neutron beam. In this work, we report a time evolution calculation of $$mu$$CF in a two-layered hydrogen isotope target.

Journal Articles

Velocity distribution in the subchannels of a pin bundle with a wrapping wire; Evaluation of the Reynolds number dependence in a three-pin bundle

Aizawa, Kosuke; Hiyama, Tomoyuki; Nishimura, Masahiro; Kurihara, Akikazu; Ishida, Katsuji*

Mechanical Engineering Journal (Internet), 8(4), p.20-00547_1 - 20-00547_11, 2021/08

A sodium-cooled fast reactor has been designed to attain a high burn-up core in commercialized fast reactor cycle systems. The sodium-cooled fast reactor adopts a wire spacer between fuel pins. The wire spacer performs functions of securing the coolant channel and the mixing between subchannels. In high burn-up fuel subassemblies, the fuel pin deformation due to swelling and thermal bowing may decrease the local flow velocity in the subassembly and influence the heat removal capability. Therefore, understanding the flow field in a wire-wrapped pin bundle is important. This study performed particle image velocimetry (PIV) measurements using a wire-wrapped three-pin bundle water model to grasp the flow field in the subchannel under conditions, including the laminar to turbulent regions. In the region away from the wrapping wire, the maximum flow velocity was increased by decreasing the Re number. Accordingly, the PIV measurements using the three-pin bundle geometry without the wrapping wire were also conducted to understand the effect of the wrapping wires on the flow field in the subchannel. The results confirmed that the mixing due to the wrapping wire occurred, even in the laminar condition. These experimental results are useful not only for understanding the pin bundle thermal hydraulics, but also for the code validation.

Journal Articles

Practical tests of neutron transmission imaging with a superconducting kinetic-inductance sensor

Vu, TheDang; Shishido, Hiroaki*; Aizawa, Kazuya; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Soyama, Kazuhiko; Miyajima, Shigeyuki*; et al.

Nuclear Instruments and Methods in Physics Research A, 1006, p.165411_1 - 165411_8, 2021/08

 Times Cited Count:0 Percentile:0.03(Instruments & Instrumentation)

Journal Articles

Experimental and analytical investigation on local damage to reinforced concrete panels subjected to projectile impact, 1; Penetration damage mode due to normal impact

Kang, Z.; Okuda, Yukihiko; Nishida, Akemi; Tsubota, Haruji; Li, Y.

Proceedings of 28th International Conference on Nuclear Engineering; Nuclear Energy the Future Zero Carbon Power (ICONE 28) (Internet), 10 Pages, 2021/08

Most empirical formulas have been proposed to quantitatively evaluate local damage to reinforced concrete (RC) structures caused by a rigid projectile impact. These formulas have been derived from impact tests performed to the target structure with a normal angle, while only a few impact tests involving soft projectile to the target structure have been studied. Recently, we conducted a series of impact tests to evaluate local damage to RC panels subjected to normal and oblique impact due to rigid and soft projectiles. The final goal of our study is to establish a new formula for evaluating local damage to RC structures caused by soft projectile with oblique angle based on experimental and analytical investigation. This paper summarizes the results of experimental and analytical investigation on penetration damage mode to RC panels subjected to normal projectile impact. Through the comparison between experimental and analytical results, the validity of the analytical method is confirmed.

Journal Articles

Hybrid dynamic response test focusing on the support structure of piping systems

Okuda, Yukihiko; Nishida, Akemi; Sakai, Michiya*; Shiogama, Yuzo*; Li, Y.

Proceedings of 28th International Conference on Nuclear Engineering; Nuclear Energy the Future Zero Carbon Power (ICONE 28) (Internet), 6 Pages, 2021/08

To develop a more realistic seismic evaluation method of nuclear power plants, it is necessary to evaluate the seismic behavior considering the joints of each component that are treated as independent models during design evaluation, such as buildings, equipment, and piping systems. Particularly, the piping support structure, which is the joint between the building and piping, is important in the seismic evaluation of the piping system. While the current seismic evaluation of piping support structures is performed within the elastic range, it is important to consider the realistic elastic-plastic response of piping support structures for fragility assessment in seismic probabilistic risk assessment. However, the seismic evaluation method that considers the elastic-plastic response of piping support structures has not yet been established, and there is a need to improve seismic evaluation methods. In this study, a hybrid dynamic response test for simulating the seismic behavior of the piping support structure, including the elastic-plastic response, has been conducted. Specifically, static cyclic loading tests and hybrid dynamic response tests were conducted using four types of piping support structures to understand the basic mechanical behavior. This report presents the details of the tests and test results.

Journal Articles

Project management efforts in the decommissioning project of Tokai Reprocessing Plant

Taguchi, Shigeo; Taguchi, Katsuya; Makino, Risa; Yamanaka, Atsushi; Suzuki, Kazuyuki; Takano, Masato; Koshino, Katsuhiko; Ishida, Michihiko; Nakano, Takafumi; Yamaguchi, Toshiya

Nihon Hozen Gakkai Dai-17-Kai Gakujutsu Koenkai Yoshishu, p.499 - 502, 2021/07

In 2018, Tokai Reprocessing Plan (TRP) shifted to the decommissioning stage. In order to proceed with steady decommissioning work, TRP effort to enhance project management function. This paper describes the establishment and role of the Decommissioning Project Management Office, effectiveness of applying the project management tool and its utilization concept, and the method of materialize the equipment dismantling plan.

Journal Articles

Radiation monitoring and evaluation of exposure doses to lift the evacuation orders for the zones designated for reconstruction and recovery

Sanada, Yukihisa; Kurikami, Hiroshi; Funaki, Hironori; Yoshimura, Kazuya; Abe, Tomohisa; Ishida, Mutsushi*; Tanimori, Soichiro*; Sato, Rina

Nihon Genshiryoku Gakkai Wabun Rombunshi, 20(2), p.62 - 73, 2021/06

Japanese government starts to consider radiation protection in the "specific reconstruction reproduction base area" of which evacuation order will be lifted by 2023. It is essential to grab the present situations of radiation contamination and evaluate exposure dose in the area to realize the plan. Many surveys have evaluated the distributions of air dose rate and exposure dose has been estimated based on the results since the Fukushima Daiichi Nuclear Power Plant accident. Nevertheless, more detailed information on exposure is needed for the areas because its radiation level is relatively high. That is also to help make prudent evaluation plan. This study aimed to evaluate the detailed contamination situation there and estimate exposure dose with considering areal circumstances. Investigations were carried out for (1) airborne survey of air dose rate using an unmanned helicopter (2) evaluation of airborne radiocesium and (3) estimation of external/internal effective doses for typical activity patterns assumed.

Journal Articles

Analysis of residual stress in steel bar processed by cold drawing and straightening

Nishida, Satoru*; Nishino, Soichiro*; Sekine, Masahiko*; Oka, Yuki*; Harjo, S.; Kawasaki, Takuro; Suzuki, Hiroshi; Morii, Yukio*; Ishii, Yoshinobu*

Materials Transactions, 62(5), p.667 - 674, 2021/05

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

Ultrafast surface Dirac fermion dynamics of Sb$$_2$$Te$$_3$$-based topological insulators

Sumida, Kazuki; Ishida, Yukiaki*; G$"u$dde, J.*; H$"o$fer, U.*; Shin, S.*; Kimura, Akio*

Progress in Surface Science, 96(2), p.100628_1 - 100628_15, 2021/05

 Times Cited Count:0 Percentile:0.07(Chemistry, Physical)

JAEA Reports

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2019

Nakano, Masanao; Fujii, Tomoko; Nagaoka, Mika; Koike, Yuko; Yamada, Ryohei; Kubota, Tomohiro; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; Kikuchi, Masaaki*; et al.

JAEA-Review 2020-070, 120 Pages, 2021/02

JAEA-Review-2020-070.pdf:2.47MB

Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2019. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.

Journal Articles

Analytical study of perforation damage in reinforced concrete slabs subjected to oblique impact by projectiles with different nose shapes

Kang, Z.; Okuda, Yukihiko; Nishida, Akemi; Tsubota, Haruji; Li, Y.

Mechanical Engineering Journal (Internet), 8(1), p.20-00331_1 - 20-00331_16, 2021/02

Considerable research has been carried out to establish a rational assessment method for nuclear power plants against local damage caused by an accidental projectile impact. Most of the empirical formulas that have been proposed seek to quantitatively investigate local damage to reinforced concrete (RC) structures caused by a rigid projectile impact. These formulas have been derived based on impact tests performed normal to the target structure, while only a few impact tests oblique to the target structure have been studied. This study aims to propose a new formula for evaluating local damage to RC structures caused by oblique impact based on experimental and simulation results. At present, we have validated an analytical method via comparison with experimental results and have conducted simulation analyses of oblique impact assessments on RC slabs using projectile with flat nose shape. In this study, the same analytical method will be used to investigate perforation damage to RC slabs subjected to oblique impact by projectiles with hemispherical nose shapes. In this paper, the effects of projectiles' nose shapes on perforation damage to RC slabs, the residual velocity of projectiles and the time history of energy transmission will be discussed.

Journal Articles

Homogeneity of neutron transmission imaging over a large sensitive area with a four-channel superconducting detector

Vu, TheDang; Shishido, Hiroaki*; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Miyajima, Shigeyuki*; Oku, Takayuki; Soyama, Kazuhiko; Aizawa, Kazuya; et al.

Superconductor Science and Technology, 34(1), p.015010_1 - 015010_10, 2021/01

 Times Cited Count:2 Percentile:72.02(Physics, Applied)

Journal Articles

Ultrafast carrier dynamics and light-induced functionalizations of topological insulators

Sumida, Kazuki; Ishida, Yukiaki*; Kimura, Akio*

Nihon Butsuri Gakkai-Shi, 75(12), p.756 - 760, 2020/12

Journal Articles

Analytical study of perforation damage to reinforced concrete slabs subjected to oblique impact by projectiles with different nose shapes

Kang, Z.; Okuda, Yukihiko; Nishida, Akemi; Tsubota, Haruji; Li, Y.

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 7 Pages, 2020/08

Plenty of researches have been carried out to establish a rational assessment method for nuclear power plants against local damage caused by accidental projectile impact. Most of the empirical formulas have been proposed for quantitatively investigating the local damage to reinforced concrete (RC) structures caused by rigid projectile impact. These formulas have been derived on the basis of impact tests performed perpendicular to the target structure, while few impact tests oblique to the target structures have been studied. The final objective of this study is to propose a new formula for evaluating the local damage to RC structures caused by oblique impact based on experimental and simulation results. At present, we have validated an analytical method via comparison with experimental results and have conducted simulation analyses of oblique impact assessments on RC slab using various projectiles with flat nose shape by this method. In this study, the same analytical method will be applied to investigate the perforation damage to RC slab subjected to oblique impact by projectiles with hemispherical nose shape. In this paper, the effects of projectile's nose shape on the local damage of RC slab, the residual velocity of projectile and the time history of energy transmission will be discussed.

353 (Records 1-20 displayed on this page)