First demonstration of a single-end readout position-sensitive optical fiber radiation sensor inside the Fukushima Daiichi Nuclear Power Station based on wavelength-resolving analysis

Terasaka, Yuta; Sato, Yuki; Uritani, Akira*

Nuclear Instruments and Methods in Physics Research A, 1062, p.169227_1 - 169227_6, 2024/05

https://doi.org/10.1016/j.nima.2024.169227

Development of high-resolution imaging camera for alpha dust (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*

JAEA-Review 2022-065, 111 Pages, 2023/03

JAEA-Review-2022-065.pdf:6.8MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of high-resolution imaging camera for alpha dust" conducted from FY2018 to FY2021. Since the final year of this proposal was FY2021, the results for four fiscal years were summarized. The present study aims to develop a novel alpha-ray camera consisting of imaging and an energy spectrometer to find the alpha dust to reduce the risk of health damage in decommissioning. We have developed the camera with a position resolution of less than 10 m, and the measurement test for the energy spectra was operated using several alpha-ray sources with an unfolding method.

Advanced thermal-hydraulic experiments and instrumentation for heavy liquid metal reactors

Pacio, J.*; Van Tichelen, K.*; Eckert, S.*; Wondrak, T.*; Di Piazza, I.*; Lorusso, P.*; Tarantino, M.*; Daubner, M.*; Litfin, K.*; Ariyoshi, Gen; et al.

Nuclear Engineering and Design, 399, p.112010_1 - 112010_15, 2022/12

https://doi.org/10.1016/j.nucengdes.2022.112010

Heavy-liquid metals (HLMs), such as lead and lead-bismuth eutectic (LBE), are proposed as primary coolants in accelerator driven systems and next-generation fast reactors. In Europe, the reference systems using HLMs are MYRRHA (LBE) and ALFRED (lead). This article presents an overview of recent experiences and ongoing activities on pool-type and loop-type HLM experiments. Pool tests include the measurement of forced- and natural-circulation flow patterns in several scenarios representative of nominal and decay heat removal conditions. Loop tests are focused on the evaluation of specific components, like mockups of the fuel assembly, control rod and heat exchangers. They involve the measurement of global variables, such as flow rate and pressure difference, and local quantities like temperature, velocity and vibrations. Advanced instrumentation, capable of sustaining high temperatures and corrosion, is necessary for accurate measurements, often in compact geometries. In addition to traditional techniques, other instrumentation based on optical fibers, ultrasonic and electromagnetic methods are discussed.

Theoretical and experimental estimation of the relative optically stimulated luminescence efficiency of an optical-fiber-based BaFBr:Eu detector for swift ions

Hirata, Yuho; Sato, Tatsuhiko; Watanabe, Kenichi*; Ogawa, Tatsuhiko; Parisi, A.*; Uritani, Akira*

Journal of Nuclear Science and Technology, 59(7), p.915 - 924, 2022/07

https://doi.org/10.1080/00223131.2021.2017372

The reliability of dose assessment with radiation detectors is an important feature in various fields, such as radiotherapy, radiation protection, and high-energy physics. However, many detectors irradiated by high linear energy transfer (LET) radiations exhibit decreased efficiency called the quenching effect. This quenching effect depends not only on the particle LET but strongly on the ion species and its microscopic pattern of energy deposition. Recently, a computational method for estimating the relative efficiency of luminescence detectors was proposed following analysis of microdosimetric specific energy distributions simulated using the particle and heavy ion transport code system (PHITS). This study applied the model to estimate the relative optically stimulated luminescence (OSL) efficiency of BaFBr:Eu detectors. Additionally, we measured the luminescence intensity of BaFBr:Eu detectors exposed to He, C and Ne ions to verify the calculated data. The model reproduced the experimental data in the cases of adopting a microdosimetric target diameter of approximately 30-50 nm. The calculated relative efficiency exhibit ion-species dependence in addition to LET. This result shows that the microdosimetric calculation from specific energy is a successful method for accurately understanding the results of OSL measurements with BaFBr:Eu detectors irradiated by various particles.

Development of high-resolution imaging camera for alpha dust (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*

JAEA-Review 2021-044, 58 Pages, 2022/01

JAEA-Review-2021-044.pdf:3.53MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of high-resolution imaging camera for alpha dust" conducted in FY2020. The present study aims to develop a novel alpha-ray camera consisting of imaging and an energy spectrometer to find the alpha dust to reduce the risk of health damage in Decommissioning. We have developed the camera in FY2020, and the measurement test for the energy spectra. Moreover, the imaging test has been operated. In addition, we have also developed a high-dose-rate monitor system using novel scintillators with red/infra-red emission.

Challenge to advancement of debris composition and direct isotope measurement by microwave-enhanced LIBS (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; i-lab*

JAEA-Review 2021-027, 62 Pages, 2021/11

JAEA-Review-2021-027.pdf:3.06MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Challenge to advancement of debris composition and direct isotope measurement by microwave-enhanced LIBS" conducted in FY2020. Although LIBS (laser-induced breakdown spectroscopy) is commercially available for application to remote composition measurement, it is not suitable for high radiation environment due to loss in optical fibers derived from the influence of radiation, reduction in laser transmission output, and nuclear fuel debris properties. There are general concerns of the signal strength decrease. In addition, since LIBS is generally considered to be unsuitable for isotope measurement, there are problems to be improved.

Evaluation of a one-dimensional position-sensitive quartz optical fiber sensor based on the time-of-flight method for high radiation dose rate applications

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

Nuclear Instruments and Methods in Physics Research A, 996, p.165151_1 - 165151_8, 2021/04

https://doi.org/10.1016/j.nima.2021.165151

For the measurement of radiation distribution inside the Fukushima Daiichi Nuclear Power Station (FDNPS) buildings, the evaluation of a small-diameter quartz optical fiber as a one-dimensional position-sensitive sensor was conducted. The sensor determines the incident position of radiation into the fiber using the time-of-flight information of emitted Cerenkov photons in the optical fiber. Compared with the conventional sensor using the plastic scintillating fiber, the quartz optical fiber has much higher position resolution, which may be the result of the improvement of timing characteristics caused by the prompt emission mechanism of the Cerenkov radiation. Additionally, the response of position-sensitive quartz optical fiber sensor under high radiation field was evaluated, and good count rate linearity was confirmed using the 10 m long quartz optical fiber with a diameter of 0.4 mm up to the dose rate at least 20 mSv/h, and the radiation tolerance property up to the accumulated dose of 1 kGy was evaluated.

Development of high-resolution imaging camera for alpha dust (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*

JAEA-Review 2020-039, 59 Pages, 2021/01

JAEA-Review-2020-039.pdf:4.18MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2019. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of high-resolution imaging camera for alpha dust" conducted in FY2019. We have developed an imaging camera with a position resolution of less than approximately 10 m to monitor alpha dust in the nuclear plant during the decommissioning process, because the operators avoid to drawing in such dusts. Moreover, we have developed real-time monitor system with optical fiber and scintillator under high dose-rate condition.

Containment atmosphere monitoring system for design and beyond design basis accident

Bentaib, A.*; Janin, T.*; Porcheron, E.*; Magne, S.*; Leroy, M.*; Dhote, J.*; Ruffien Ciszak, A.*; Sun, Haomin

Proceedings of OECD/NEA Specialist Workshop on Advanced Measurement Method and Instrumentation for enhancing Severe Accident Management in an NPP addressing Emergency, Stabilization and Long-term Recovery Phases (SAMMI 2020) (Internet), 6 Pages, 2020/12

Real-time dosimetry system based on an optical fiber-coupled microsized photostimulable phosphor for stereotactic body radiation therapy

Yada, Ryuichi*; Maenaka, Kazusuke*; Miyamoto, Shuji*; Okada, Go*; Sasakura, Aki*; Ashida, Motoi*; Adachi, Masashi*; Sato, Tatsuhiko; Wang, T.*; Akasaka, Hiroaki*; et al.

Medical Physics, 47(10), p.5235 - 5249, 2020/10

https://doi.org/10.1002/mp.14383

The dosimeter system is capable of real-time, accurate, and precise measurement under stereotactic body radiation therapy (SBRT) conditions. The probe is smaller than a conventional dosimeter, has excellent spatial resolution, and can be valuable in SBRT with a steep dose distribution over a small field. The developed PSP dosimeter system appears to be suitable for in vivo SBRT dosimetry.