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Journal Articles

R&D status of digital technology on inverse estimation of radioactive source distributions and related source countermeasures; Fast Digital Twin Tech. in Decommissioning Field: 3D-ADRES-Indoor FrontEnd

Machida, Masahiko; Yamada, Susumu; Kim, M.; Tanaka, Satoshi*; Tobita, Yasuhiro*; Iwata, Ayako*; Aoki, Yuto; Aoki, Kazuhisa; Yanagisawa, Kenichi*; Yamaguchi, Takashi; et al.

RIST News, (70), p.3 - 22, 2024/09

Inside the Fukushima Daiichi Nuclear Power Plant (1F), there are many locations with high radiation levels due to contamination by radioactive materials that leaked from the reactor. These pose a significant obstacle to the smooth progress of decommissioning work. To help solve this issue, the Japan Atomic Energy Agency (JAEA), under a subsidy from the Ministry of Economy, Trade, and Industry's decommissioning and contaminated water management project, is conducting research and development on digital technologies to improve the radiation environment inside the decommissioning site. This project, titled "Development of Technology to Improve the Environment Inside Reactor Buildings (Enhancing Digital Technology for Environment and Source Distribution to Reduce Radiation Exposure)," began in April of FY 2023. In this project, the aim is to develop three interconnected systems: FrontEnd, Pro, and BackEnd. The FrontEnd system, based on the previously developed 3D-ADRES-Indoor (prototype) from FY 2021-2022, will be upgraded to a high-speed digital twin technology usable on-site. The Pro system will carry out detailed analysis in rooms such as the new office building at 1F, while the BackEnd system will serve as a database to centrally manage the collected and analyzed data. This report focuses on the FrontEnd system, which will be used on-site. After point cloud measurement, the system will quickly create a 3D mesh model, estimate the radiation source from dose rate measurements, and refine the position and intensity of the estimated source using recalculation techniques (re-observation instructions and re-estimation). The results of verification tests conducted on Unit 5 are also presented. Furthermore, the report briefly discusses the future research and development plans for this project.

Journal Articles

Present status of the JAEA-AMS-TONO (2023FY)

Fujita, Natsuko; Miyake, Masayasu; Matsubara, Akihiro*; Ishii, Masahiro*; Takahashi, Yuto*; Watanabe, Takahiro; Jinno, Satoshi; Nishio, Tomohiro*; Ogawa, Yumi; Kimura, Kenji; et al.

Dai-25-Kai AMS Shimpojiumu Hokokushu (Internet), 3 Pages, 2024/03

The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has three accelerator mass spectrometers. We report the present status of the JAEA-AMS-TONO.

Journal Articles

Present status of the JAEA-AMS-TONO (2022FY)

Fujita, Natsuko; Miyake, Masayasu; Matsubara, Akihiro*; Ishii, Masahiro*; Watanabe, Takahiro; Jinno, Satoshi; Nishio, Tomohiro*; Ogawa, Yumi; Kimura, Kenji; Shimada, Akiomi; et al.

Dai-35-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.17 - 19, 2024/03

The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has three accelerator mass spectrometers. We report the present status of the JAEA-AMS-TONO.

Journal Articles

Development of new synchronized data system for J-PARC RCS

Takahashi, Hiroki; Saha, P. K.; Yoshimoto, Masahiro; Sawabe, Yuki*

Journal of Physics; Conference Series, 2687(7), p.072019_1 - 072019_5, 2024/01

 Times Cited Count:0 Percentile:0.00(Physics, Atomic, Molecular & Chemical)

In J-PARC 3 GeV Rapid Cycling Synchrotron, the synchronized data system using reflective memory has been constructed. In order to support the requirement of using larger size data in high intensity beam operation in the future, a new synchronized data generation method has been proposed. The new method implements in the measurement system the functions performed by the high-level computer in the current system, thereby realizing synchronized data generation using data transfer via LAN. In this study, we have constructed a test bench for the new synchronized data system that implements the proposed method and verified its performance. This result leads to the development of the new synchronized data system based on data transfer via LAN. In this paper, we describe the outline of the new synchronized data generation method and the results of performance tests.

Journal Articles

Development of new data acquisition system for several beam monitors in J-PARC RCS

Yoshimoto, Masahiro; Takahashi, Hiroki; Harada, Hiroyuki; Chimura, Motoki; Fuwa, Yasuhiro; Hayashi, Naoki; Kuriyama, Yasutoshi*; Sawabe, Yuki*; Hatakeyama, Shuichiro*

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.839 - 843, 2023/11

In the J -PARC 3GeV synchrotron accelerator (RCS), a new signal processing system for beam monitors is been developing to replace the existing system for the main beam monitors that monitor the stability of the accelerator: beam loss monitor, beam position monitor and beam current monitor. The new system will consist of a TAG server and an ADC module that can be used commonly for the three main monitors. The main design concepts of the new system are: (1) the TAG server divides various beam J-PARC tag information to each ADC module, (2) the ADC module converts acquisition data from beam monitors to digital signals by ADC and performs high-speed analysis by FPGA with switching analysis methods to suit each monitor, (3) the ADC module periodically outputs the analysis data with tag information by packing the signal processing data of all shots for about 10 seconds, and also outputs any one shot data on-demand, and (4) the raw waveform data, the latest four shots of FFT-related data in the process of analysis and bunch data for each cycle are stored in the internal memory of the ADC module, and the data can be read out as needed. In this presentation, we will report on the progress of the data acquisition test of tag information reading and beam monitor signals using the prototype under development.

Journal Articles

Upgrade of acquisition and monitoring system for J-PARC accelerator PPS

Watanabe, Kazuhiko*; Niki, Kazuaki*; Takahashi, Hiroki; Yamamoto, Noboru*; Yoshimoto, Masahiro; Fukuta, Shimpei*

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.844 - 847, 2023/11

J-PARC Personnel Protection System (PPS) acquires and displays data using by PPS Data System. PPS Data System has been using SCADA software, but it has become difficult to handle increased data due to the limited number of signals. Then, it became necessary to build PPS Data System using different software. Therefore, we decided to construct a new system using EPICS, which has been used in the J-PARC control system. On the other hand, PPS is a system that guarantees the safety of personnel, so it cannot be shut down for long periods of time. In addition, it is the most important safety system and must maintain high reliability and stability, so it would be dangerous to update the entire system in a short period of time. Therefore, we decided to divide the PPS Data System by function and replace it with the new system partially while operating the current system. This allows us to verify the operation of the updated parts and correct any problems without compromising the functionality of the PPS, and to construct a new system with high reliability and stability. This presentation will provide an overview of the new system, the updating process, and the progress.

Journal Articles

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

 Times Cited Count:7 Percentile:74.40(Nuclear Science & Technology)

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Journal Articles

Identification and quantification of a $$^{60}$$Co radiation source under an intense $$^{137}$$Cs radiation field using an application-specific CeBr$$_3$$ spectrometer suited for use in intense radiation fields

Kaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Takahashi, Hiroyuki*

Journal of Nuclear Science and Technology, 59(8), p.983 - 992, 2022/08

 Times Cited Count:2 Percentile:29.47(Nuclear Science & Technology)

Journal Articles

Development of the multi-cubic $$gamma$$-ray spectrometer and its performance under intense $$^{137}$$Cs and $$^{60}$$Co radiation fields

Kaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*

Nuclear Instruments and Methods in Physics Research A, 1010, p.165544_1 - 165544_9, 2021/09

 Times Cited Count:0 Percentile:0.00(Instruments & Instrumentation)

The number of nuclear facilities being decommissioned has been increasing worldwide, in particular following the accident of the Tokyo Electric Power Company Holdings' Fukushima Daiichi Nuclear Power Station in 2011. In these nuclear facilities, proper management of radioactive materials is required. Then, A $$gamma$$-ray spectrometer with four segmentations using small volume CeBr$$_{3}$$ scintillators with a dimension of $$5 times 5 times 5$$ $$rm{mm}^3$$ was developed. The four scintillators were coupled to a multi-anode photomultiplier tube specific to intense radiation fields. We performed the $$gamma$$-ray exposure study under $$^{137}$$Cs and $$^{60}$$Co radiation fields. Under the $$^{137}$$Cs radiation field, the relative energy resolution at 1375 mSv/h was the relative energy resolution at 1375 mSv/h was 9.2$$pm$$0.05%, 8.0$$pm$$0.08%, 8.0$$pm$$0.03%, and 9.0$$pm$$0.04% for the four channels, respectively.

JAEA Reports

Manufacture of substitutive assemblies for MONJU reactor decommissioning

Sakakibara, Hiroshi; Aoki, Nobuhiro; Muto, Masahiro; Otabe, Jun; Takahashi, Kenji*; Fujita, Naoyuki*; Hiyama, Kazuhiko*; Suzuki, Hirokazu*; Kamogawa, Toshiyuki*; Yokosuka, Toru*; et al.

JAEA-Technology 2020-020, 73 Pages, 2021/03

JAEA-Technology-2020-020.pdf:8.26MB

The decommissioning is currently in progress at the prototype fast breeder reactor Monju. Fuel assemblies will be taken out of its core for the first step of the great task. Fuel assemblies stand on their own spike plugged into a socket on the core support plate and support with adjacent assemblies through their housing pads each other, resulting in steady core structure. For this reason, some substitutive assemblies are necessary for the purpose of discharging the fuel assemblies of the core. Monju side commissioned, therefore, Plutonium Fuel Development Center to manufacture the substitutive assemblies and the Center accepted it. This report gives descriptions of design, manufacture, and shipment in regard to the substitutive assemblies.

JAEA Reports

Investigation and consideration on evaluation of radiation doses to residents in the case of a nuclear emergency

Hashimoto, Makoto; Kinase, Sakae; Munakata, Masahiro; Murayama, Takashi; Takahashi, Masa; Takada, Chie; Okamoto, Akiko; Hayakawa, Tsuyoshi; Sukegawa, Masato; Kume, Nobuhide*; et al.

JAEA-Review 2020-071, 53 Pages, 2021/03

JAEA-Review-2020-071.pdf:2.72MB

In the case of a nuclear accident or a radiological emergency, the Japan Atomic Energy Agency (JAEA), as a designated public corporation assigned in the Disaster Countermeasures Basic Act and the Armed Attack Situation Response Law, undertakes technical supports to the national government and local governments. The JAEA is requested to support to evaluate radiation doses to residents in a nuclear emergency, which is specified in the Basic Disaster Management Plan and the Nuclear Emergency Response Manual. For the dose evaluation, however, its strategy, target, method, structure and so on have not been determined either specifically or in detail. This report describes the results of investigation and consideration discussed in the "Working Group for Radiation Dose Evaluation at a Nuclear Emergency" established within the Nuclear Emergency Assistance and Training Center to discuss technical supports for radiation dose evaluation to residents in the case of a nuclear emergency, and aims at contributing to specific and detailed discussion and activities in the future for the national government and local governments, also within the JAEA.

Journal Articles

Gamma-ray spectroscopy with a CeBr$$_3$$ scintillator under intense $$gamma$$-ray fields for nuclear decommissioning

Kaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*; et al.

Nuclear Instruments and Methods in Physics Research A, 988, p.164900_1 - 164900_8, 2021/02

 Times Cited Count:14 Percentile:82.89(Instruments & Instrumentation)

An increasing number of nuclear facilities have been decommissioned worldwide following the 2011 accident of the TEPCO' Fukushima Daiichi Nuclear Power Station. During the decommissioning, radioactive materials have to be retrieved under proper management. In this study, a small cubic CeBr$$_3$$ spectrometer with dimensions of 5 mm $$times$$ 5 mm $$times$$ 5 mm was manufactured to perform $$gamma$$-ray spectroscopy under intense $$gamma$$-ray fields. Furthermore, thanks to a fast digital process unit and a customized photomultiplier, the device could perform $$gamma$$-ray spectroscopy at dose rates of over 1 Sv/h. The energy resolution (FWHM) at 662 keV ranged from 4.4% at 22 mSv/h to 5.2% at 1407 mSv/h for a $$^{137}$$Cs radiation field. Correspondingly, at 1333 keV, it ranged from 3.1% at 26 mSv/h to 4.2% at 2221 mSv/h for a $$^{60}$$Co radiation field, which suggested to realize $$gamma$$-ray assessment of $$^{134}$$Cs, $$^{137}$$Cs, $$^{60}$$Co, and $$^{154}$$Eu at dose rates of over 1 Sv/h.

Journal Articles

Simple pretreatment method for tritium measurement in environmental water samples using a liquid scintillation counter

Nakasone, Shunya*; Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; et al.

Plasma and Fusion Research (Internet), 16, p.2405035_1 - 2405035_5, 2021/02

Removal of impurities such as organic and other types of dissolved matters from environmental water samples is required for precise analysis of tritium with a liquid scintillation counting method. In general, a distillation method is a conventional one for tritium analysis in environmental water samples, but is a time-consuming process that takes 24 hours for removal of impurities. We have proposed a rapid pretreatment method for tritium analysis, that uses ion exchange resins. In this study, we performed batch experiments, to evaluate the effectiveness of the ion exchange resins on the tritium measurement. The results obtained demonstrated that removal of impurities in the sample water by ion exchange resins can be achieved during a short period of time (i.e., in 5 min).

Journal Articles

Development and application of a $$^3$$He neutron spin filter at J-PARC

Okudaira, Takuya; Oku, Takayuki; Ino, Takashi*; Hayashida, Hirotoshi*; Kira, Hiroshi*; Sakai, Kenji; Hiroi, Kosuke; Takahashi, Shingo*; Aizawa, Kazuya; Endo, Hitoshi*; et al.

Nuclear Instruments and Methods in Physics Research A, 977, p.164301_1 - 164301_8, 2020/10

 Times Cited Count:20 Percentile:89.09(Instruments & Instrumentation)

Journal Articles

Japanese population dose from natural radiation

Omori, Yasutaka*; Hosoda, Masahiro*; Takahashi, Fumiaki; Sanada, Tetsuya*; Hirao, Shigekazu*; Ono, Koji*; Furukawa, Masahide*

Journal of Radiological Protection, 40(3), p.R99 - R140, 2020/09

 Times Cited Count:27 Percentile:71.24(Environmental Sciences)

UNSCEAR and the Nuclear Safety Research Association report the annual effective doses from cosmic rays, terrestrial radiation, inhalation and ingestion from natural sources. In this study, radiation doses from natural radiation sources in Japan were reviewed with the latest knowledge and data. Total annual effective dose from cosmic-ray exposure can be evaluated as 0.29 mSv. The annual effective dose from external exposure to terrestrial radiation for Japanese population can be evaluated as 0.33 mSv using the data of nationwide survey by the National Institute of Radiological Sciences. The Japan Chemical Analysis Center (JCAC) performed the nationwide radon survey using a unified method for radon measurements in indoor, outdoor and workplace. The annual effective dose for radon inhalation was estimated using a current dose conversion factor, and the values were estimated to be 0.50 mSv. The annual effective dose from thoron was reported as 0.09 mSv by UNSCEAR and then the annual effective dose from inhalation can be described as 0.59 mSv. According to the report of large scale survey of foodstuff by JCAC, the effective dose from main radionuclides due to dietary intake can be evaluated to be 0.99 mSv. Finally, Japanese population dose from natural radiation can be assessed as 2.2 mSv which is near to the world average value of 2.4 mSv.

Journal Articles

Preliminary investigation of pretreatment methods for liquid scintillation measurements of environmental water samples using ion exchange resins

Nakasone, Shunya*; Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; et al.

Plasma and Fusion Research (Internet), 15, p.2405027_1 - 2405027_3, 2020/05

A quick preprocessing system for tritium analysis of environmental samples is important to judge environmental influence of tritium releases due to accident or tritium-handling facilities. Analysis of tritium in water samples with liquid scintillation counting method requires removal of impurities such as organic matter and ion species from water samples. Generally, a distillation method is adopted as a pretreatment of analysis for tritium; however, the distillation method is a time-consuming process. The aim of this study is to evaluate a rapid pretreatment method for tritium analysis with ion exchange resin. From batch and column experiments that used inland water and ion exchange resin, we confirmed removals of impurities of the water sample and that the removal of impurities was possible for a short time (by 5 minutes).

Journal Articles

Confinement of hydrogen molecules at graphene-metal interface by electrochemical hydrogen evolution reaction

Yasuda, Satoshi; Tamura, Kazuhisa; Terasawa, Tomoo; Yano, Masahiro; Nakajima, Hideaki*; Morimoto, Takahiro*; Okazaki, Toshiya*; Agari, Ryushi*; Takahashi, Yasufumi*; Kato, Masaru*; et al.

Journal of Physical Chemistry C, 124(9), p.5300 - 5307, 2020/03

 Times Cited Count:18 Percentile:58.72(Chemistry, Physical)

Confinement of hydrogen molecules at graphene-substrate interface has presented significant importance from the viewpoints of development of fundamental understanding of two-dimensional material interface and energy storage system. In this study, we investigate H$$_{2}$$ confinement at a graphene-Au interface by combining selective proton permeability of graphene and the electrochemical hydrogen evolution reaction (electrochemical HER) method. After HER on a graphene/Au electrode in protonic acidic solution, scanning tunneling microscopy finds that H$$_{2}$$ nanobubble structures can be produced between graphene and the Au surface. Strain analysis by Raman spectroscopy also shows that atomic size roughness on the graphene/Au surface originating from the HER-induced strain relaxation of graphene plays significant role in formation of the nucleation site and H$$_{2}$$ storage capacity.

Journal Articles

Development of field estimation technique and improvement of environmental tritium behavior model

Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; et al.

Plasma and Fusion Research (Internet), 14(Sp.2), p.3405099_1 - 3405099_4, 2019/06

The Large Helical Device of the National Institute for Fusion Science started D-D experiments in 2017. To ensure the safety of the facility, it is important to develop evaluation methods for environmental tritium transfer. Tritiated water (HTO) in atmosphere and soil is transferred to plants, and organically bound tritium (OBT) is formed by photosynthesis. Prediction of OBT formation is important, because OBT accumulates in plants and causes dose through ingestion. The objective of this study is to estimate environmental tritium transfer using a simple compartment model and practical parameters. We proposed a simple compartment model consisting of air-soil-plant components, and tried to validate the model by comparison with a sophisticated model, SOLVEG. In this study, we plan to add wet deposition to the model and obtain parameters from measurements of soil permeability and tritium concentrations in air, soil and plants. We also establish rapid pretreatment methods for OBT analysis.

Journal Articles

Improvement of motor control system in J-PARC linac and RCS

Takahashi, Hiroki; Miura, Akihiko; Sawabe, Yuki; Yoshimoto, Masahiro; Suzuki, Takahiro*; Kawase, Masato*

Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.2180 - 2182, 2018/06

The stepping motor control system used in the profile monitor and RCS collimator of J-PARC is configured by VME-based. Most of these pieces of control equipment are in use for more than 10 years. Therefore, countermeasures against aging of equipment are necessary. In addition, it is necessary to implement countermeasures against malfunction of the control system, which is thought to be caused by radiation. In 2016, a malfunction occurred in the motor control system of the RCS collimator. Taking this as a starting point, we began developing a motor control system that can ensure equipment safety even if a malfunction occurs. In this paper, we show the inference of the cause of this malfunction and present details of the developed high-safety motor control system.

Journal Articles

A Failure investigation of the beam collimator system in the J-PARC 3 GeV rapid cycling synchrotron

Okabe, Kota; Yamamoto, Kazami; Kamiya, Junichiro; Takayanagi, Tomohiro; Yamamoto, Masanobu; Yoshimoto, Masahiro; Takeda, Osamu*; Horino, Koki*; Ueno, Tomoaki*; Yanagibashi, Toru*; et al.

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.853 - 857, 2017/12

The most important issue is to reduce the uncontrolled beam loss in the high intensity hadron accelerator such as J-PARC proton accelerators. The J-PARC 3 GeV Synchrotron (RCS) has a collimator system which narrows a high intensity beam in the RCS. After startup of RCS in 2007, the collimator system of the RCS worked well. However, in April 2016, vacuum leakage at the collimator system occurred during the maintenance operation. To investigate a cause of the failure, we took apart iron shields of the collimator reducing exposed dose of operators. As a result of inspection, we succeeded to identify the cause of the vacuum leakage failure. In this presentation, we report the failure investigation of the beam collimator system in the RCS.

141 (Records 1-20 displayed on this page)