Development of a practical tritiated water monitor to supervise the discharge of treated water from Fukushima Daiichi Nuclear Power Plant

Sanada, Yukihisa; Oshikiri, Keisuke*; Kanno, Marina*; Abe, Tomohisa

Nuclear Instruments and Methods in Physics Research A, 1062, p.169208_1 - 169208_7, 2024/05

https://doi.org/10.1016/j.nima.2024.169208

As part of the decommissioning work at the Fukushima Daiichi Nuclear Power Plant (FDNPP), the release of stored treated water began in 2023. In this study, we developed a practical tritium monitor to continuously monitor the concentration of tritiated water, as confirmed by batch sampling measurements at the FDNPP. The monitor is arranged with a flow cell detector comprising inexpensive plastic scintillator pellets and incorporating simultaneous measurements by three detectors, a veto detector, and lead shielding to reduce the influence of environmental -rays. The system reached a detection limit of 911 Bq L-1 with a measurement time of 30 min, which is lower than the discharge standard for tritiated water of 1,500 Bq L-1. The system can also qualitatively distinguish the presence of disturbances due to interfering radionuclides other than tritium or background radiation using the -ray spectrum.

Rod-shaped pulse shape discrimination plastic scintillation detectors applied for neutron source direction survey

Koizumi, Mitsuo; Mochimaru, Takanori*; Hironaka, Kota; Takahashi, Tone; Yamanishi, Hirokuni*; Wakabayashi, Genichiro*

Nuclear Instruments and Methods in Physics Research A, 1042, p.167424_1 - 167424_6, 2022/11

https://doi.org/10.1016/j.nima.2022.167424

no abstracts in English

First demonstration of a novel single-end readout type position-sensitive optical fiber radiation sensor based on wavelength-resolved photon counting

Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*

Nuclear Instruments and Methods in Physics Research A, 1034, p.166793_1 - 166793_6, 2022/07

https://doi.org/10.1016/j.nima.2022.166793

Development experience for plastic scintillation fiber after the accident of the Fukushima Daiichi Nuclear Power Plant

Sanada, Yukihisa

Hokeikyo Nyusu, (68), p.2 - 6, 2021/10

https://www.irm.or.jp/news68.pdf

Due to the impact of the Fukushima Daiichi Nuclear Power Station accident (hereinafter referred to as the power station accident) of Tokyo Electric Power Company Holdings, Inc., the surrounding environment was contaminated with radioactive substances such as radioactive cesium. After the nuclear power plant accident, plastic scintillation fiber is one of the applied wire and surface radiation measurement techniques. This paper summarizes the development process from a series of development to the introduction of the actual machine.

Application to contaminated water management in the Fukushima Daiichi Nuclear Power Station using the plastic scintillation fiber

Sanada, Yukihisa; Yamada, Tsutomu*; Sato, Yoshiharu; Nishizawa, Yukiyasu; Ishibashi, Satoshi*; Watanabe, Masahisa; Torii, Tatsuo

JAEA-Research 2016-011, 52 Pages, 2016/09

JAEA-Research-2016-011.pdf:10.54MB

In the Tokyo Electric Power Co.,Inc. the Fukushima Dai-ichi Nuclear Power Station, management of the contaminated water becomes the social problem, and the situation that severe correspondence is necessary continues to prevent an outflow to the ocean. Plastic scintillation fiber (PSF) can apply as technique to direct measure the concentration of radioactive material in the water at a tank and drainage. In this paper, the results of fundamental test was summarized to apply for monitoring of leakage to the tank and monitoring of drainage in the Fukushima Dai-ichi Nuclear Power Station.

Evaluation of the cryogenic tensile properties for aramid fiber rod

Saito, Toru; Okubo, Toshikazu*; Izumi, Keisuke*; Okawa, Yoshinao*; Kobayashi, Norihiro*; Yamazaki, Toru; Kawano, Katsumi; Isono, Takaaki

Teion Kogaku, 50(8), p.400 - 408, 2015/08

https://doi.org/10.2221/jcsj.50.400

Aramid fiber-reinforced plastic (AFRP) has been developed as a structural material that has the advantages of light weight and high strength. In this study, tensile tests were carried out to measure the tensile properties of AFRP rod on the market for reinforcement of concrete at room temperature, 77 K and 4.2 K. Especially at cryogenic temperatures, it is difficult to perform a tensile test of the bar because the specimen slips through the jig grip. To prevent the rod from slipping, tensile tests were carried out with some filling conditions. The applicable and appropriate tensile test conditions were established by modifying the jig grip, treating the surface of the rod and using cryogenic epoxy infill to grip the rod. They were more than 1100 MPa. Additionally, the AFRP rod included a temperature dependence in which the Young's modulus increased as the test temperature decreased. It was confirmed that the Young's modulus increased because aramid fiber was more dominant than epoxy.

Technology of measurement for radiation distribution on bottom of water; Application for measurement of irrigation ponds in Fukushima Prefecture

Sanada, Yukihisa; Torii, Tatsuo

Nihon Genshiryoku Gakkai-Shi ATOMO, 57(2), p.94 - 98, 2015/02

https://doi.org/10.3327/jaesjb.57.2_94

In Fukushima, quick and direct technique to measure a wide area of bottom of water is needed. We developed the plastic scintillation fiber (PSF) since accident at 1F. Therefore, the PSF was applied to measurement of irrigation pond. Here, the measuring method and the monitoring result are reported.

Radiation crosslinking of poly(butylene succinate) in the presence of low concentration of trimethallyl isocyanurate and its properties

Suhartini, M.; Mitomo, Hiroshi*; Nagasawa, Naotsugu; Yoshii, Fumio; Kume, Tamikazu

Journal of Applied Polymer Science, 88(9), p.2238 - 2246, 2003/00

https://doi.org/10.1002/app.11944

no abstracts in English

A study on improvements in accuracy of nuclear data measurements using -ray spectroscopic methods

Furutaka, Kazuyoshi

JNC TN8400 2000-028, 70 Pages, 2000/10

JNC-TN8400-2000-028.pdf:1.71MB

This report describes the study done by the author as a postdoctoral research associate at Japan Nuclear Cycle Development Institute. This report is divided into two parts: improvements in accuracy in determination of thermal neutron capture cross sections, and improvements in accuracy of photo-nuclear absorption cross section measurements using the HHS. (1)In the measurements of thermal neutron capture cross sections using an activation method, accuracies of the final results attained are limited by (1) accuracy of -ray peak detection efficiencies, and (2) accuracies of -ray emission probabilities. In this study; to determine thermal neutron capture cross sections more accurately, the following researches have been done using a newly developed three-dimensional coincidence measurement system: (1)accurate determination of -ray standard sources using a - coincidence method, for precise calibration of -ray peak detection efficiency, and (2) development of a - coincidence measurement system using a plastic scintillation detector as a -ray detector, for the determination of -ray emission probabilities of short-lived nuclides, and measurement of -ray emission probabilities of Tc nuclide using the coincidence system. (2)To transform radioactive nuclides with small thermal neutron capture cross sections, use of photonuclear absorption reaction has been suggested. In order to transform these nuclides efficiently using the reaction, one has to know detailed behavior of the photo-absorption cross sections. In this study, a Monte-Carlo simulation code has been used to create a standard set of -ray response functions of the high-resolution high-energy spectrometer (HHS), to enable reliable analyses of the data obtained by the spectrometer.

Dose distributions in a plastic phantom irradiated by 40- and 65-MeV quasi-monoenergetic neutrons

Nakane, Yoshihiro; Sakamoto, Yukio

Proceedings of 10th International Congress of the International Radiation Protection Association (IRPA-10) (CD-ROM), 5 Pages, 2000/05

no abstracts in English