Development of the performance evaluation method for small multicopter vertical mobility in a narrow environment

Yamada, Taichi; Suzuki, Soichiro; Ito, Rintaro; Ota, Yua*; Kaneko, Eiichiro*; Ogane, Katsuji*; Kawabata, Kuniaki

Advanced Robotics, 40(5), p.259 - 270, 2026/03

https://doi.org/10.1080/01691864.2025.2573056

We develop a test method to evaluate the vertical moving performance of an unmanned aircraft system (UAS) in a narrow environment, specifically performance for ascending through a narrow aperture. This research aims to boost the UAS industry by pushing for the expansion of UAS use into various places and situations. UAS users should know whether the UAS performance is enough to achieve their objectives and what UAS suits them. However, discussing what/how much UASs can do is complex, especially in a place or situation affecting some UAS functions. Thus, the test method provides an easy-to-understand evaluation of UAS performance for mobility to access a destination in a narrow environment, even for UAS users without technical knowledge. To develop an acceptable test method for the UAS industry, we repeatedly held demonstrations and discussions with UAS manufacturers and users to incorporate their opinions from the early stages of this research. In addition, the experiments show that the test method appropriately indicates the difference in UAS performance. This paper describes the approach of UAS performance evaluation to promote the UAS industry, the development along with UAS users' opinions, and the result of the experiments to compare the type of UAS and consideration.

Development of a probabilistic risk assessment method for combined hazards; A Classification and modeling framework for multihazard events

Choi, B.; Nishida, Akemi; Tsutsumi, Hideaki*; Takada, Tsuyoshi

Proceedings of Probabilistic Safety Assessment and Management & Asian Symposium on Risk Assessment and Management (PSAM17 & ASRAM2024) (Internet), 8 Pages, 2024/10

The Fukushima Daiichi Nuclear Power Plant accident highlighted the importance of developing safety assessment methods that consider multihazard events involving numerous simultaneously occurring events such as earthquakes (shaking) and tsunamis (submersion). When addressing such multihazard events, traditional methods often focus on assessing the load combinations of general structures in their structural designs and adopt simple selection criteria. However, these methods fall short when evaluating, countering, and screening external events, such as earthquakes, tsunamis, strong winds, and concentrated heavy rainfall, that occur simultaneously or in a chain. To address this, we reviewed existing literature on multihazard assessment methods, focusing particularly on scenarios involving earthquake and tsunami events. Based on concepts and basic theories, we examined various methods for addressing multihazard scenarios and classified their characteristics. Specifically, several multihazard scenarios were surveyed, and the relationships between multiple hazards were organized. In addition, common causes leading to combined events, their mutual influences, and potential cascading effects were analyzed.

Development of test method for evaluation of UAS mobility capability in GNSS-denied environment

Yamada, Taichi; Abe, Hiroyuki*; Ogane, Katsuji*; Kawabata, Kuniaki

ROBOMECH Journal (Internet), 10, p.13_1 - 13_8, 2023/06

https://doi.org/10.1186/s40648-023-00251-1

Although Unmanned Aircraft System (UAS) has significant industrial potential, it is not easy to discuss how well UAS performs in places and situations where the UAS is deployed. Therefore, we designed the approach for UAS evaluation and developed the evaluation methods that make it possible to compare the UAS performances in easy-to-understand for UAS users, people without technical knowledge focusing on GNSS-denied environments. The development proceeded with the demonstration and discussion with UAS manufacturers and users, and we repeatedly improved the evaluation methods with their opinions. Finally, we confirm that the evaluation methods can describe the difference between the UAS's performance by an experiment.

Survey on the planning process for waste characterization with statistical methods; Data quality objectives process

Murakami, Masashi; Sasaki, Toshiki

JAEA-Review 2022-004, 106 Pages, 2022/06

JAEA-Review-2022-004.pdf:3.95MB

A numerous analytical data will be required for the characterization of the radioactive waste stored in Japan Atomic Energy Agency toward their processing and disposal. A "Data Quality Objectives (DQO) Process" is widely applied as a tool for the development of a cost-effective characterization plan in the overseas nuclear sites. The DQO Process is a multi-step planning process developed by the United States Environmental Protection Agency (EPA), and can be used for the planning of a scientifically rigorous and cost-effective data collection program for the various projects involving the collection of the environmental data. We have considered to reduce the cost required for the future characterization of the stored waste by applying the statistical methods and have performed a literature survey on the DQO Process. The survey effort was focused on the guidance documents of the DQO Process published by the EPA and was also spent for the related matters such as a quality system of the EPA and the activities beyond the DQO Process as well as the examples of the application at the nuclear sites. In this report, the details on the planning procedure using the DQO Process are reviewed together with the background information such as why DQO Process was developed, what kind of transition was occurred, and how it is currently used in the EPA. The examples on the application for various objects at Hanford Site in the United States, where has the various legacy waste generated in the past activities and has the big environmental problems, are also reviewed. This report summarizes the important matters and methodology on the planning with the statistical sampling methods. It also provides the examples of the approaches for the complex objects, and will therefore be helpful in the future planning for the various kind of the waste characterization.

Technical Note: Validation of a material assignment method for a retrospective study of carbon-ion radiotherapy using Monte Carlo simulation

Chang, W.*; Koba, Yusuke*; Furuta, Takuya; Yonai, Shunsuke*; Hashimoto, Shintaro; Matsumoto, Shinnosuke*; Sato, Tatsuhiko

Journal of Radiation Research (Internet), 62(5), p.846 - 855, 2021/09

https://doi.org/10.1093/jrr/rrab028

With the aim of developing a revaluation tool of treatment plan in carbon-ion radiotherapy using Monte Carlo (MC) simulation, we propose two methods; one is dedicated to identify realistic-tissue materials from a CT image with satisfying the well-calibrated relationship between CT numbers and stopping power ratio (SPR) provided by TPS, and the other is to estimate dose to water considering the particle- and energy-dependent SPR between realistic tissue materials and water. We validated these proposed methods by computing depth dose distribution in homogeneous and heterogeneous phantoms composed of human tissue materials and water irradiated by a 400 MeV/u carbon beam with 8 cm SOBP using a MC simulation code PHITS and comparing with results of conventional treatment planning system (TPS). Our result suggested that use of water as a surrogate of real tissue materials, which is adopted in conventional TPS, is inadequate for dose estimation from secondary particles because their production rates cannot be scaled by SPR of the primary particle in water. We therefore concluded that the proposed methods can play important roles in the reevaluation of the treatment plans in carbon-ion radiotherapy.

Concerning aging of nuclear fuel material use facilities Examination of measures to improve safety assessment methods

Sakamoto, Naoki; Fujishima, Tadatsune; Mizukoshi, Yasutaka

Hozengaku, 19(2), p.125 - 126, 2020/07

The five post-irradiation examination facilities in JAEA's Oarai research and development institute have been operated for over 40 years in order to investigate the irradiation performance of fast reactor fuel materials. The equipment associated with these facilities has been managed to maintain secure from the problems occurred in the process of aging. Therefore, we established a safety assessment method for aging facilities in 2002, and we have been conducting maintenance management of facilities since then. In this study, improvement plans of the safety assessment method are considered in order to solve the issues detected as a result of analysis of past maintenance information.

Toward technological contributions to remote operations in the decommissioning of the Fukushima Daiichi Nuclear Power Station

Kawabata, Kuniaki

Japanese Journal of Applied Physics, 59(5), p.050501_1 - 050501_9, 2020/05

https://doi.org/10.35848/1347-4065/ab82ad

This paper describes the decommissioning work being undertaken at the Fukushima Daiichi Nuclear Power Station of the Tokyo Electric Power Company Holdings Inc.'s (FDNPS) using remote controlled robotic systems, as well as lessons learned from past remote task executions. We also summarize the issues to be considered in promoting safe, steady, and efficient decommissioning based on past experiences. In response to these issues, we are developing test methods for performance evaluation of the robots for nuclear decommissioning, robot simulator for operator proficiency training, and information generation methods to improve the operator's status awareness. The current status of technological development is also described.

An Image selection method from image sequence collected by remotely operated robot for efficient 3D reconstruction

Hanari, Toshihide; Kawabata, Kuniaki; Nakamura, Keita*; Naruse, Keitaro*

Proceedings of International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP 2020) (Internet), p.242 - 245, 2020/02

In this paper, we propose an image selection method to realize efficient three-dimensional (3D) reconstruction from image sequence collected by a remotely operated robot. The proposed method is to select adequate images for reconstruction computation based on optical flow measures. We confirmed that the proposed method can select adequate images for 3D reconstruction from the image sequence recorded by the remotely operated robot that is commanded stop-and-go motions. As a result, we demonstrated a 3D reconstruction could be performed efficiently with relatively few images that were selected by the proposed method.

Study on the evaluation method to determine the radioactivity concentration in radioactive waste generated from post-irradiation examination facilities, 2

Tsuji, Tomoyuki; Hoshino, Yuzuru; Sakai, Akihiro; Sakamoto, Yoshiaki; Suzuki, Yasuo*; Machida, Hiroshi*

JAEA-Technology 2017-010, 75 Pages, 2017/06

JAEA-Technology-2017-010.pdf:2.31MB

It is necessary for reasonable disposal to be studied on evaluation methods to determine radioactivity concentrations in the radioactive wastes, which is generated from post-irradiation examination (PIE) facilities, for establishment of reasonable confirmation methods concerning radioactive wastes generated from research, industrial, and medical facilities. It has been chosen the PIE facilities of NUCLEAR DEVELOPMENT CORPORATION as a model for this study. As a result, it has been confirmed that the theoretical methods are applied for the important nuclides (H-3, C-14, Co-60, Ni-63, Sr-90, Tc-99, Cs-137, Eu-154, U-234, U-235, U-238, Pu-238, Pu-239, Pu-240, Pu-241, Am-241 and Cm-244).

Examination of decontamination of various materials at houses in difficult-to-return zone

Mori, Airi; Tanabe, Tsutomu; Wada, Takao; Kato, Mitsugu

JAEA-Technology 2017-006, 38 Pages, 2017/03

JAEA-Technology-2017-006.pdf:2.98MB

Large quantities of radioactive materials were released into the environment as a result of the Fukushima Daiichi Nuclear Power Station accident. Residential areas and forest areas near the power station were contaminated with the radioactive materials. Outside of the houses, schools and the other buildings are being decontaminated by national authority and local government. On the other hand, the materials (such as walls, floors, or windows) which constitute the houses are not decontaminated officially. In order to prepare decontamination methods that can be applied easily, we conducted examinations of decontamination for various materials in houses. Fibrous materials, woods, glasses, concretes, plastics, vinyl chloride materials, metals and synthetic leathers were used in our examinations. These materials were collected from houses in difficult-to-return zone, and were contaminated by radioactive materials released by the accident. Dry methods (suction, wiping, adsorption and peelable coating), wet methods (wiping, brushing, polishing and washing) and physical method (peeling of materials) were used for decontamination. As a result of our examinations, materials with low water permeability, such as glasses, concretes, vinyl chloride materials and metals, were able to be decontaminated efficiently (about 90% reduction) by using wet methods. Materials with high water permeability like woods were relatively well decontaminated by peelable coating (about 60%-70% reduction). In addition to the examination described above, the difference of contamination reduction effect between chemical properties of detergents and the effect of rubbing of peelable coating were also examined. Finally, the most effective method was summarized based on these examinations.