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Journal Articles

Long-term variations in $$^{129}$$I seawater concentrations off Fukushima and potential of 129I as an oceanographic tracer for ALPS-treated water

Suzuki, Takashi; Otosaka, Shigeyoshi*; Takata, Hyoe*; Kuwabara, Jun; Nakanishi, Takahiro; Ikenoue, Tsubasa

Environmental Science & Technology, 60(17), p.13123 - 13131, 2026/04

https://doi.org/10.1021/acs.est.5c18263

As a results of the 2011 Fukushima Daiichi Nuclear Power Plant accident, long-lived radioactive $$^{129}$$I has been released into the environment, with additional releases beginning in 2023 through ALPS-treated water. To study its long-term variation and potential as an oceanographic tracer, $$^{129}$$I concentrations in seawater off Fukushima were measured from 2012 to 2024. The highest concentration, 445$$times$$10$$^{-8}$$ Bq/L, was observed in 2013 near the plant. Levels have since declined toward the pre-accident value of 1.76$$times$$10$$^{-8}$$ Bq/L. Spatial and temporal changes in the $$^{129}$$I/$$^{137}$$Cs ratio indicate the influence of small water masses and support its use as a tracer in areas with complex ocean circulation.

Journal Articles

A New analytical technique utilizing the PdI$$_{2}$$ target for measurement of $$^{129}$$I in environmental samples by accelerator mass spectrometry

Honda, Maki; Takaku, Yuichi*; Sakaguchi, Aya*; Matsuzaki, Hiroyuki*; Sueki, Keisuke*

Journal of Radioanalytical and Nuclear Chemistry, 334(8), p.5809 - 5820, 2025/08

https://doi.org/10.1007/s10967-025-10324-7
 Times Cited Count：0 Percentile：0.00(Chemistry, Analytical)

A series of in-house PdI$$_{2}$$ standards appropriate for AMS was prepared by quantitatively mixing the $$^{129}$$I/$$^{127}$$I isotope standard solution and $$^{127}$$I solution. The dominant interferences from $$^{104, 105}$$Pd $$^{4+}$$ were successfully suppressed by adjusting the electrostatic cylindrical analyser, etc., to select the ion beams finely. As a result, the $$^{129}$$I/$$^{127}$$I atom ratios of PdI$$_{2}$$ prepared from the seawater and dolomite samples agreed with those prepared as AgI, respectively. The pretreatment time for the new method was shortened by 33% compared to the conventional method. This study demonstrated a new approach to $$^{129}$$I analysis in AMS that departs from conventional methods.

Journal Articles

Integral experiment of $$^{129}$$I(n, $$gamma$$) using fast neutron source in the "YAYOI" reactor

Nakamura, Shoji; Toh, Yosuke; Kimura, Atsushi; Hatsukawa, Yuichi*; Harada, Hideo

Journal of Nuclear Science and Technology, 59(7), p.851 - 865, 2022/07

https://doi.org/10.1080/00223131.2021.2011794
 Times Cited Count：2 Percentile：16.03(Nuclear Science & Technology)

The present study performed integral experiments of $$^{129}$$I using a fast-neutron source reactor "YAYOI" of the University of Tokyo to validate evaluated nuclear data libraries. The iodine-129 sample and flux monitors were irradiated by fast neutrons in the Glory hole of the YAYOI reactor. Reaction rates of $$^{129}$$I were obtained by measurement of decay gamma-rays emitted from $$^{130}$$I. The validity of the fast-neutron flux spectrum in the Glory hole was confirmed by the ${it C/E}$ ratios of the reaction rates of flux monitors. The experimental reaction rate of $$^{129}$$I was compared with that calculated with both the fast-neutron flux spectrum and evaluated nuclear data libraries. The present study revealed that the evaluated nuclear data of $$^{129}$$I cited in JENDL-4.0 should be reduced as much as 18% in neutron energies ranging from 10 keV to 3 MeV, and supported the reported data by Noguere ${it et al.}$ below 100 keV.

Journal Articles

Iodine-129 in the Tokai Reprocessing Plant and the environment

Nakano, Masanao

Hoken Butsuri (Internet), 56(1), p.17 - 25, 2021/03

https://doi.org/10.5453/jhps.56.17

The Tokai Reprocessing Plant is the first reprocessing plant in Japan which started hot test in 1977, and had reprocessed 1140 tons of spent nuclear fuel by May 2007. The gaseous and liquid radioactive wastes has been discharged to the environment. Since iodine-129 ($$^{129}$$I) is one of the most important nuclides for environmental impact assessment. Therefore, $$^{129}$$I in the exhaust and effluent has been controlled, and a precise analysis method of $$^{129}$$I in the environmental samples was developed, and the concentration of 129I in the environment was investigated. This report presents an overview of these activities. Not limited to $$^{129}$$I on reprocessing facilities, it is essential for nuclear operators to reduce the amount released to the environment in the spirit of ALARA, and to continuously develop the further upgrading environmental monitoring methods and evaluation methods in order to foster a sense of safety and security among residents living in the vicinity of the facilities.

Journal Articles

Vertical distributions of Iodine-129 and iodide in the Chukchi Sea and Bering Sea

Miwa, Kazuji; Obata, Hajime*; Suzuki, Takashi

Journal of Nuclear Science and Technology, 57(5), p.537 - 545, 2020/05

https://doi.org/10.1080/00223131.2019.1699189
 Times Cited Count：2 Percentile：15.49(Nuclear Science & Technology)

This study investigated the vertical distribution of Iodine-129 ($$^{129}$$I) which is mainly produced by European nuclear reprocessing plants in the Chukchi Sea and Bering Sea. $$^{129}$$I was found to be distributed almost uniformly in fallout level, and an increasing in $$^{129}$$I concentration levels caused by high $$^{129}$$I water inflow from the Atlantic Ocean was not observed. Additionally, we revealed the vertical distribution of iodide, one chemical form of iodine, from the Bering Shelf area to the Chukchi Sea for the first time. The increasing tendency of iodide near sea bottom was observed.

Journal Articles

Performance of the new iodine-129 beamline at JAERI-AMS

Suzuki, Takashi; Aramaki, Takafumi; Kitamura, Toshikatsu; Togawa, Orihiko

Nuclear Instruments and Methods in Physics Research B, 223-224(1-4), p.87 - 91, 2004/08

https://doi.org/10.1016/j.nimb.2004.04.021
 Times Cited Count：13 Percentile：62.16(Instruments & Instrumentation)

At the Japan Atomic Energy Research Institute, an Accelerator Mass Spectrometer which was installed in Mutsu establishment has two independent beam lines. We verified the precision, the accuracy and the detection limit at this AMS iodine line. Acceptance test for $$^{129}$$I measurement was carried out on two consecutive days and the $$^{129}$$I/$$^{127}$$I ratios obtained during these two days were (7.497$$pm$$0.119) $$times$$10 $$^{-11}$$ and (7.209$$pm$$0.050) $$times$$10 $$^{-11}$$ , respectively and the relative standard deviations from the $$^{129}$$I/$$^{127}$$I averages per sample were 1.6 % and 0.7 %, respectively. Seawater samples were collected in the western North Pacific and off Rokkasho, Japan before the operation of a nuclear fuel reprocessing plant. Seawater samples preparation for $$^{129}$$I -AMS measurement was performed by an extraction method. This paper was summarized the performance of this AMS iodine line and measurement results of $$^{129}$$I/$$^{127}$$I ratio in seawater samples.

Journal Articles

Applicability of a model predicting iodine-129 profile in a silver nitrate silica-gel column for dissolver off-gas treatment of fuel reprocessing

Mineo, Hideaki; Goto, Minoru; Iizuka, Masaru*; Fujisaki, Susumu; Hagiya, Hiromichi*; Uchiyama, Gunzo

Separation Science and Technology, 38(9), p.1981 - 2001, 2003/05

https://doi.org/10.1081/SS-120020130
 Times Cited Count：26 Percentile：66.22(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

A Simple model predicting iodine profile in a packed bed of silica-gel impregnated with silver nitrate

Mineo, Hideaki; Goto, Minoru; Iizuka, Masaru*; Fujisaki, Susumu; Uchiyama, Gunzo

Journal of Nuclear Science and Technology, 39(3), p.241 - 247, 2002/03

https://doi.org/10.3327/jnst.39.241
 Times Cited Count：30 Percentile：84.26(Nuclear Science & Technology)

no abstracts in English

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