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JAEA Reports

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2022

Kokubun, Yuji; Nakada, Akira; Seya, Natsumi; Nagaoka, Mika; Koike, Yuko; Kubota, Tomohiro; Hirao, Moe; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; et al.

JAEA-Review 2023-052, 118 Pages, 2024/03

JAEA-Review-2023-052.pdf:3.67MB

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 2022. 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.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2022

Kokubun, Yuji; Nakada, Akira; Seya, Natsumi; Koike, Yuko; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; Nagai, Shinji; et al.

JAEA-Review 2023-046, 164 Pages, 2024/03

JAEA-Review-2023-046.pdf:4.2MB

The Nuclear Fuel Cycle Engineering Laboratories conducts environmental radiation monitoring around the reprocessing plant in accordance with the "Safety Regulations for Reprocessing Plant of JAEA, Part IV: Environmental Monitoring". This report summarizes the results of environmental radiation monitoring conducted during the period from April 2022 to March 2023 and the results of dose calculations for the surrounding public due to the release of radioactive materials into the atmosphere and ocean. In the results of the above environmental radiation monitoring, many items were affected by radioactive materials emitted from the accident at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company, Incorporated (changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016), which occurred in March 2011. Also included as appendices are an overview of the environmental monitoring plan, an overview of measurement methods, measurement results and their changes over time, meteorological statistics results, radioactive waste release status, and an evaluation of the data which deviated of the normal range.

JAEA Reports

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2021

Nakada, Akira; Kanai, Katsuta; Kokubun, Yuji; Nagaoka, Mika; Koike, Yuko; Yamada, Ryohei*; Kubota, Tomohiro; Hirao, Moe; Yoshii, Hideki*; Otani, Kazunori*; et al.

JAEA-Review 2022-079, 116 Pages, 2023/03

JAEA-Review-2022-079.pdf:2.77MB

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 2021. 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.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2021

Nakada, Akira; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Futagawa, Kazuo; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; et al.

JAEA-Review 2022-078, 164 Pages, 2023/03

JAEA-Review-2022-078.pdf:2.64MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2021 to March 2022. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.

Journal Articles

Semiconductor pulse power supplies for accelerators at J-PARC

Takayanagi, Tomohiro; Ono, Ayato; Fuwa, Yasuhiro; Shinozaki, Shinichi; Horino, Koki*; Ueno, Tomoaki*; Sugita, Moe; Yamamoto, Kazami; Oguri, Hidetomo; Kinsho, Michikazu; et al.

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.242 - 246, 2023/01

At J-PARC, semiconductor short pulse power supplies to replace kicker power supplies and semiconductor long pulse power supplies to replace klystron power supply systems are under construction. We have fabricated a 40kV/2kA/1.2s unit power supply that employs a linear transformer drivers (LTD) system for kickers. Currently, we are working on a high voltage insulating cylinder insulator that suppresses corona discharges using only the insulator structure, without using insulating oil. In addition, the MARX system was adopted for klystron power supply system. A main circuit unit for 8kV/60A/830s rectangular pulse output and an 800V/60A correction circuit unit that improves the flat top droop from 10% to 1% were manufactured. Furthermore, a 2.2kV/2.4kW high voltage SiC inverter charger has been fabricated for this MARX power supply. The presentation will report the evaluation results of each test and prospects for semiconductor pulse power supplies.

Journal Articles

Study on the relation between the crystal structure and thermal stability of FeUO $_{4}$ and CrUO $_{4}$

Akiyama, Daisuke*; Kusaka, Ryoji; Kumagai, Yuta; Nakada, Masami; Watanabe, Masayuki; Okamoto, Yoshihiro; Nagai, Takayuki; Sato, Nobuaki*; Kirishima, Akira*

Journal of Nuclear Materials, 568, p.153847_1 - 153847_10, 2022/09

https://doi.org/10.1016/j.jnucmat.2022.153847

Times Cited Count：3 Percentile：68.71(Materials Science, Multidisciplinary)

FeUO $_{4}$ , CrUO $_{4}$ , and Fe $_{x}$ Cr $_{1-x}$ UO $_{4}$ are monouranates containing pentavalent U. Even though these compounds have similar crystal structures, their formation conditions and thermal stability are significantly different. To determine the factors causing the difference in thermal stability between FeUO $_{4}$ and CrUO $_{4}$ , their crystal structures were evaluated in detail. A Raman band was observed at 700 cm $^{-1}$ in all the samples. This Raman band was derived from the stretching vibration of the O-U-O axis band, indicating that Fe $_{x}$ Cr $_{1-x}$ UO $_{4}$ was composed of a uranyl-like structure in its lattice regardless of its "x"' value. Mssbauer measurements indicated that the Fe in FeUO $_{4}$ and Fe $_{x}$ Cr $_{1-x}$ UO $_{4}$ were trivalent. Furthermore, Fe $_{x}$ Cr $_{1-x}$ UO $_{4}$ lost its symmetry around Fe $^{mathrm{III}}$ with increasing electron densities around Fe $^{mathrm{III}}$ , as the abundance of Cr increased. These results suggested no significant structural differences between FeUO $_{4}$ and CrUO $_{4}$ . Thermogravimetric measurements for UO $_{2}$ , FeUO $_{4}$ , and CrUO $_{4}$ showed that the temperature at which FeUO $_{4}$ decomposed under an oxidizing condition (approximately 800 $^{circ}$ C) was significantly lower than the temperature at which the decomposition of CrUO $_{4}$ started (approximately 1250 $^{circ}$ C). Based on these results, we concluded that the decomposition of FeUO $_{4}$ was triggered by an "in-crystal" redox reaction, i.e., Fe $^{mathrm{III}}$ U $^{mathrm{V}}$ Fe $^{mathrm{II}}$ U $^{mathrm{VI}}$ , which would not occur in the CrUO $_{4}$ lattice because Cr $^{mathrm{III}}$ could never be reduced under the investigated condition. Finally, the existence of Cr $^{mathrm{III}}$ in FexCr $_{1-x}$ UO $_{4}$ effectively suppressed the decomposition of the Fe $_{x}$ Cr $_{1-x}$ UO $_{4}$ crystal, even at a very low Cr content.

Journal Articles

Structure, stability, and actinide leaching of simulated nuclear fuel debris synthesized from UO $_{2}$ , Zr, and stainless-steel

Kirishima, Akira*; Akiyama, Daisuke*; Kumagai, Yuta; Kusaka, Ryoji; Nakada, Masami; Watanabe, Masayuki; Sasaki, Takayuki*; Sato, Nobuaki*

Journal of Nuclear Materials, 567, p.153842_1 - 153842_15, 2022/08

https://doi.org/10.1016/j.jnucmat.2022.153842

Times Cited Count：4 Percentile：78.52(Materials Science, Multidisciplinary)

To understand the chemical structure and stability of nuclear fuel debris consisting of UO $_{2}$ , Zr, and Stainless Steel (SUS) generated by the Fukushima Daiichi Nuclear Power Plant accident in Japan in 2011, simulated debris of the UO $_{2}$ -SUS-Zr system and other fundamental component systems were synthesized and characterized. The simulated debris were synthesized by heat treatment for 1 to 12 h at 1600 $^{circ}$ C, in inert (Ar) or oxidative (Ar + 2% O $_{2}$ ) atmospheres. $^{237}$ Np and $^{241}$ Am tracers were doped for the leaching tests of these elements and U from the simulated debris. The characterization of the simulated debris was conducted by XRD, SEM-EDX, Raman spectroscopy, and Mssbauer spectroscopy, which provided the major uranium phase of the UO $_{2}$ -SUS-Zr debris was the solid solution of U $^{mathrm{IV}}$ O $_{2}$ (s.s.) with Zr(IV) and Fe(II) regardless of the treatment atmosphere. The long-term immersion test of the simulated debris in pure water and that in seawater revealed the macro scale crystal structure of the simulated debris was chemically very stable in the wet condition for a year or more. Furthermore, the leaching test results showed that the actinide leaching ratios of U, Np, Am from the UO $_{2}$ -SUS-Zr debris were very limited and less than 0.08 % for all the experiments in this study.

Journal Articles

Uranium dissolution and uranyl peroxide formation by immersion of simulated fuel debris in aqueous H $_{2}$ O $_{2}$ solution

Kumagai, Yuta; Kusaka, Ryoji; Nakada, Masami; Watanabe, Masayuki; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Sasaki, Takayuki*

Journal of Nuclear Science and Technology, 59(8), p.961 - 971, 2022/08

https://doi.org/10.1080/00223131.2021.2023055

Times Cited Count：2 Percentile：53.91(Nuclear Science & Technology)

We investigated potential degradation of fuel debris caused by H $_{2}$ O $_{2}$ , which is the oxidant of major impact from water radiolysis. We performed leaching experiments on different kinds of simulated debris comprising U, Fe, Cr, Ni, and Zr in an aqueous H $_{2}$ O $_{2}$ solution. Chemical analysis of the leaching solution showed that U dissolution was induced by H $_{2}$ O $_{2}$ . Raman analysis after the leaching revealed that uranyl peroxides were formed on the surface of the simulated debris. These results demonstrate that uranyl peroxides are possible alteration products of fuel debris from H $_{2}$ O $_{2}$ reaction. However, the sample in which the main uranium-containing phase was a U-Zr oxide solid solution showed much less uranium dissolution and no Raman signal of uranyl peroxides. Comparison of these results indicates that formation of an oxide solid solution of Zr with UO $_{2}$ improves the stability of fuel debris against H $_{2}$ O $_{2}$ reaction.

Journal Articles

A Study of H $_{2}$ O $_{2}$ -induced oxidative degradation of simulated fuel debris

Kumagai, Yuta; Kusaka, Ryoji; Nakada, Masami; Watanabe, Masayuki; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Sasaki, Takayuki*

Hoshasen Kagaku (Internet), (113), p.61 - 64, 2022/04

The severe accident at TEPCO's Fukushima Daiichi Nuclear Power Station resulted in generation of fuel debris. The fuel debris is in contact with water and the radiolysis of water can accelerate degradation of the debris. The analysis of particles sampled from inside or near the damaged reactors indicates the complicated compositions of the fuel debris. It is challenging to estimate the effect of water radiolysis on such a complicated material. Therefore, in this study, we investigated the potential degradation process by leaching experiments of simulated fuel debris in aqueous H $_{2}$ O $_{2}$ solution. The results show that the reaction of H $_{2}$ O $_{2}$ induced uranium dissolution from most of the samples and then formation of uranyl peroxides. In contrast, a sample that had U-Zr oxide solid solution as the major phase exhibited remarkable resistance to H $_{2}$ O $_{2}$ . These findings revealed that the degradation of the simulated debris reflects the reactivity and stability of the uranium phase in the matrices.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2020

Nakada, Akira; Nakano, Masanao; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Nemoto, Masashi; Tobita, Keiji; Futagawa, Kazuo; Yamada, Ryohei; Uchiyama, Rei; et al.

JAEA-Review 2021-062, 163 Pages, 2022/02

JAEA-Review-2021-062.pdf:2.87MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2020 to March 2021. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.

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

Thermodynamic evidence for nematic superconductivity in Cu $_{x}$ Bi $_{2}$ Se $_{3}$

Yonezawa, Shingo*; Tajiri, Kengo*; Nakata, Suguru*; Nagai, Yuki; Wang, Z.*; Segawa, Koji*; Ando, Yoichi*; Maeno, Yoshiteru*

Nature Physics, 13(2), p.123 - 126, 2017/02

https://doi.org/10.1038/nphys3907

Times Cited Count：198 Percentile：99.01(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Reactor antineutrino monitoring with a plastic scintillator array as a new safeguards method

Oguri, Shugo*; Kuroda, Yasuhiro*; Kato, Yo*; Nakata, Ryoko*; Inoue, Yoshizumi*; Ito, Chikara; Minowa, Makoto*

Nuclear Instruments and Methods in Physics Research A, 757, p.33 - 39, 2014/09

https://doi.org/10.1016/j.nima.2014.04.065

Times Cited Count：42 Percentile：95.71(Instruments & Instrumentation)

We developed a segmented reactor antineutrino detector made of plastic scintillators for the nuclear safeguard application and demonstrate almost unmanned field operation at a commercial power plant reactor. We observed the difference of the reactor antineutrino flux with the reactor ON and OFF above the ground outside the reactor building.

Journal Articles

Self-radiation effects and glassy nature of magnetic transition in AmO revealed by $^{17}$ O-NMR

Tokunaga, Yo; Nishi, Tsuyoshi; Nakada, Masami; Ito, Akinori*; Sakai, Hironori; Kambe, Shinsaku; Homma, Yoshiya*; Honda, Fuminori*; Aoki, Dai*; Walstedt, R. E.*

Physical Review B, 89(21), p.214416_1 - 214416_8, 2014/06

https://doi.org/10.1103/PhysRevB.89.214416

Times Cited Count：7 Percentile：31.93(Materials Science, Multidisciplinary)

The magnetic phase transition near K in AmO has been investigated microscopically by means of $^{17}$ O NMR. To avoid complexities arising from sample aging associated with the alpha decay of $^{243}$ Am, all measurements have been performed within 40 days after sample synthesis. Even during such a short period, however, a rapid change of NMR line shape has been observed at 1.5 K, suggesting that the ground state of AmO is very sensitive to disorder. We have also confirmed the loss of $^{17}$ O NMR signal intensity over a wide temperature range below , and more than half of oxygen nuclei are undetectable at 1.5 K. This behavior reveals the persistence of slow and distributed spin fluctuations down to temperatures well below . In the paramagnetic state, strong NMR line broadening and spatially inhomogeneous spin fluctuations have been observed. The results are all indicative of short-range, spin-glass-like character for the magnetic transition in this system.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2012

Sumiya, Shuichi; Watanabe, Hitoshi; Miyagawa, Naoto; Nakano, Masanao; Nakada, Akira; Fujita, Hiroki; Takeyasu, Masanori; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; et al.

JAEA-Review 2013-056, 181 Pages, 2014/03

JAEA-Review-2013-056.pdf:6.22MB

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2011

Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Nagaoka, Mika; et al.

JAEA-Review 2013-009, 195 Pages, 2013/06

JAEA-Review-2013-009.pdf:3.35MB

Journal Articles

A Mobile antineutrino detector with plastic scintillators

Kuroda, Yasuhiro*; Oguri, Shugo*; Kato, Yo*; Nakata, Ryoko*; Inoue, Yoshizumi*; Ito, Chikara; Minowa, Makoto*

Nuclear Instruments and Methods in Physics Research A, 690, p.41 - 47, 2012/10

https://doi.org/10.1016/j.nima.2012.06.040

Times Cited Count：36 Percentile：91.73(Instruments & Instrumentation)

We propose a new type segmented antineutrino detector made of plastic scintillators for the nuclear safeguard application. A small prototype was built and tested to measure background events. A satisfactory unmanned field operation of the detector system was demonstrated. Besides, a detailed Monte Carlo simulation code was developed to estimate the antineutrino detection efficiency of the detector.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2010

Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Kokubun, Yuji; et al.

JAEA-Review 2012-015, 166 Pages, 2012/05

JAEA-Review-2012-015.pdf:3.53MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2010 to March 2011. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. in 2011 March. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data exceeded the normal range of fluctuation by the accidental release was evaluated in the appendices.

Journal Articles

Results of environmental radiation monitoring at the Nuclear Fuel Cycle Engineering Laboratories, JAEA, following the Fukushima Daiichi Nuclear Power Plant accident

Takeyasu, Masanori; Nakano, Masanao; Fujita, Hiroki; Nakada, Akira; Watanabe, Hitoshi; Sumiya, Shuichi; Furuta, Sadaaki

Journal of Nuclear Science and Technology, 49(3), p.281 - 286, 2012/03

https://doi.org/10.1080/00223131.2012.660014

Times Cited Count：25 Percentile：85.94(Nuclear Science & Technology)

As a response to the Fukushima Daiichi Nuclear Power Plant accident, emergency environmental radiation monitoring was performed at the Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency (JAEA). This paper provisionally describes the results of the monitoring including ambient radiation dose rate and radioactivity concentrations in airborne and fallout. The ambient radiation dose rate began to increase since about 1:00 on March 15 2011, and varied with three peak dose rate of several thousand Gy/h at 8:00 on March 15, at 5:00 on March 16, and at 4:00 on March 21. The variation over time in radioactivity concentrations in airborne and fallout almost showed the same tendency as that of the dose rate. The fallout of $^{137}$ Cs for 1 month from March 15 to April 15 was about 120 times higher than that in May 1986 after the Chernobyl accident. The internal dose by inhalation was estimated from the airborne concentration observed.

Journal Articles

Solid-state NMR study of actinide dioxides

Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Chudo, Hiroyuki; Osaka, Masahiko; Miwa, Shuhei; Nishi, Tsuyoshi; Nakada, Masami; Ito, Akinori; Homma, Yoshiya*

Materials Research Society Symposium Proceedings, Vol.1444, p.149 - 158, 2012/00

https://doi.org/10.1557/opl.2012.1001

Times Cited Count：0 Percentile：0.11(Materials Science, Multidisciplinary)

Besides the importance of AnO series (An; U, Np, Pu, Am) as a nuclear fuel, the magnetic properties of these compounds at low temperatures are particularly interesting. Their surprisingly varied physical properties continue to be of interest for both theory and experiment. In this study, we have performed NMR studies for the series of actinide dioxides. On the basis of $^{17}$ O-NMR studies, exotic magnetic orderings associated with multipole degrees of freedom on 5 electrons have been identified in UO (dipolar + quadrupolar ordering) and NpO (octupolar + quadrupolar ordering), in contrast with the non-magnetic ground state of PuO. In AmO, our $^{17}$ O-NMR data provide the first microscopic evidence for a phase transition as a bulk property in this system.