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Collaborative Laboratories for Advanced Decommissioning Science; National Institutes of Natural Sciences*
JAEA-Review 2025-009, 48 Pages, 2025/07
JAEA-Review-2025-009.pdf:2.19MB
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 FY2023. 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 FY2021, this report summarizes the research results of the "Development of the continuous monitoring of tritium water by mid-infrared laser spectroscopy" conducted from FY2021 to FY2023. The present study aims to demonstrate the principle for rapid measurement of tritiated water at a concentration level of 60 Bq/cc using a cavity ring-down spectroscopy system with a mid-infrared laser. In fiscal year 2023, research focused on (1) developing the cavity ring-down apparatus and (2) evaluating hydrogen isotope composition and preparing standard samples under environmental conditions (subcontracted to Hirosaki University). For (1), an optical bench was set up at the NIFS to perform laser absorption spectroscopy of various hydrogen isotope concentrations, enabling the evaluation of measurement sensitivity and establishment of guidelines. The light amplification of a quantum cascade laser, was further developed, achieving light amplification of a 4.3 
m quantum cascade laser with an iron ion-doped medium, yielding a maximum output of 390 mW with a linewidth of less than 30 MHz. For (2), standard samples were prepared by diluting commercially available heavy water with BG water (tritium-free water) to create samples with approximately 100 Bq/L. Isotope ratio measurements were conducted indoors and outdoors using a high-time-resolution atmospheric water vapor collection system for tritium measurement, and daily measurements of the hydrogen isotope ratio (
D) were conducted. The relationship between D and tritium concentration in atmospheric water vapor in Hirosaki City was evaluated. Thus, the principle for the rapid measurement of tritiated water using a mid-infrared laser was successfully demonstrated.
Collaborative Laboratories for Advanced Decommissioning Science; National Institutes of Natural Sciences*
JAEA-Review 2024-025, 33 Pages, 2024/10
JAEA-Review-2024-025.pdf:1.54MB
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 FY2022. 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 FY2021, this report summarizes the research results of the "Development of the continuous monitoring of tritium water by mid-infrared laser spectroscopy" conducted in FY2022. The present study aims to demonstrate the principle of short-time measurement of tritiated water at the "60 Bq/cc level" using a cavity ring-down measurement system with a mid-infrared laser. To achieve the above goal, (1) research on the cavity ring-down system and (2) evaluation of hydrogen isotope composition under environmental conditions and preparation of standard samples (subcontractor: Hirosaki University) were conducted this fiscal year.
Collaborative Laboratories for Advanced Decommissioning Science; National Institutes of Natural Sciences*
JAEA-Review 2022-059, 34 Pages, 2023/01
JAEA-Review-2022-059.pdf:1.58MB
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 FY2021, this report summarizes the research results of the "Development of the continuous monitoring of tritium water by mid-infrared laser spectroscopy" conducted in FY2021. The present study aims to demonstrate the principle of short-time measurement of tritiated water at the "60 Bq/cc level" using a cavity ring-down measurement system with a mid-infrared laser. In order to achieve the above goal, (1) research on the cavity ring-down system and (2) evaluation of hydrogen isotope composition under environmental conditions and preparation of standard samples (subcontractor: Hirosaki University) were conducted this fiscal year. In (1), a mid-infrared cavity ring-down test was conducted. An optical bench (3 m 
1.2 m) was set up in the laboratory, …