Choi, B.; Nishida, Akemi; Kawata, Manabu; Shiomi, Tadahiko; Li, Y.
JAEA-Research 2021-017, 174 Pages, 2022/03
Standard methods such as lumped mass models have been used in the assessment of seismic safety and the design of building structures in nuclear facilities. Recent advances in computer capabilities allow the use of three-dimensional finite element (3D FE) models to account for the 3D behavior of buildings, material nonlinearity, and the nonlinear soil-structure interaction effect. Since the 3D FE model enables more complex and high-level treatment than ever before, it is necessary to ensure the reliability of the analytical results generated by the 3D FE model. Guidelines for assuring the dependability of modeling techniques and the treatment of nonlinear aspects of material properties have already been created and technical certifications have been awarded in domains other than nuclear engineering. The International Atomic Energy Agency performed an international benchmark study in nuclear engineering. Multiple organizations reported on the results of seismic response studies using the 3D FE model based on recordings from the Niigata-ken Chuetsuoki Earthquake in 2007. The variation in their analytical results was significant, indicating an urgent need to improve the reliability of the analytical results by standardization of the analytical methods using 3D FE models. Additionally, it has been pointed out that it is necessary to understand the 3D behavior in the seismic fragility assessment of buildings and equipment, which requires evaluating the realistic nonlinear behavior of building facilities when assessing their seismic fragility. In view of these considerations, a standard guideline for the seismic response analysis method using a 3D FE model was produced by incorporating the latest knowledge and findings in this area. The purpose of the guideline is to improve the reliability of the seismic response analysis method using 3D FE model of reactor buildings. The guideline consists of a main body, commentaries, and appendixes; it also provides standard procedures
Ichihara, Yoshitaka*; Nakamura, Naohiro*; Moritani, Hiroshi*; Horiguchi, Tomohiro*; Choi, B.
Nihon Genshiryoku Gakkai Wabun Rombunshi, 21(1), p.1 - 14, 2022/03
In this study, we aim to approximately evaluate the effect of nonlinearity of reinforced concrete structures through seismic response analysis using the equivalent linear analysis method. A simulation analysis was performed for the ultimate response test of the shear wall of the reactor building used in an international competition by OECD/NEA in 1996. The equivalent stiffness and damping of the shear wall were obtained from the trilinear skeleton curves proposed by the Japan Electric Association and the hysteresis curves proposed by Cheng et al. The dominant frequency, maximum acceleration response, maximum displacement response, inertia force-displacement relationship, and acceleration response spectra of the top slab could be simulated well up to a shear strain of approximately =2.010. The equivalent linear analysis used herein underestimates the maximum displacement response at the time of ultimate fracture of approximately =4.010. Moreover, the maximum shear strain of the shear wall could not capture the locally occurring shear strain compared with that of the nonlinear analysis. Therefore, when employing this method to evaluate the maximum shear strain and test results, including those during the sudden increase in displacement immediately before the fracture, sufficient attention must be paid to its applicability.
Choi, B.; Nishida, Akemi; Shiomi, Tadahiko; Kawata, Manabu; Li, Y.
Proceedings of 28th International Conference on Nuclear Engineering; Nuclear Energy the Future Zero Carbon Power (ICONE 28) (Internet), 7 Pages, 2021/08
In the seismic safety assessment of building structures in nuclear facilities, lumped mass models are conventionally used. However, they cannot possess the required high-accuracy evaluation of nuclear facilities, such as the local response at the equipment location in a reactor building. In this point of view, a seismic response analysis method using a three-dimensional finite element (3D FE) model is indispensable. Although, it has been reported that the analysis results obtained using 3D FE models vary greatly depending on the experience and knowledge of analysts, the quality of analysis results should be insured by developing a standard analysis method. In the Japan Atomic Energy Agency, we have developed a guideline for seismic response analysis methods that adopt 3D FE models of reactor buildings. The guideline consists of a main body, commentary, and several supplements; it also includes procedures, recommendations, points of attention, and a technical basis for conducting seismic response analysis using 3D FE models of reactor buildings. In this paper, the outline of the guideline and analysis examples based on the guideline are presented.
Kawakubo, Yoko; Stevens, R.*; Pickett, S.*; Sekine, Megumi; Noro, Naoko; Inoue, Naoko
Proceedings of INMM & ESARDA Joint Annual Meeting (Internet), 10 Pages, 2021/08
Nakagawa, Yosuke; Sukegawa, Hidetoshi; Naoi, Yosuke; Inoue, Naoko; Noro, Naoko; Okuda, Masahiro
Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2020/11
The physical protection exercise field, a facility equipped with various types of equipment such as sensors, cameras and fences that are used at nuclear facilities, is an effective tool for training on nuclear security at ISCN/JAEA, if it is carried out in-person. Due to the COVID-19 pandemic, the virtual tour of the facility is developed for the online training courses so that they could be more effective. The article explains the initial development of the virtual tour with some improvement inspired by using it on some occasions as well as a prospect of effective use of the virtual tour based on its characteristics.
Horiguchi, Naoki; Miyahara, Naoya; Uesawa, Shinichiro; Yoshida, Hiroyuki; Osaka, Masahiko
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05
For source term evaluation from reactor buildings (RBs) in LWR severe accidents, we have launched to develop an evaluation method of FP aerosol particle deposition onto surfaces of internal structures in an RB based on computational fluid dynamics (CFD). This paper describes development of a CFD simulation tool as the base part of the evaluation method. A preliminary simulation for a representative RB under a representative flow condition was conducted to confirm the tool performance by roughly grasping the deposition behaviors of FP aerosol particle and decontamination factor (DF) in the RB. Calculation results showed that most of aerosol particles were deposited along with gas flow formed by the internal structures in the RB, demonstrating the advantageous feature of the present CFD tool. The DFs from 4 to 14 were obtained with increase of the particle diameters from 0.1 to 10 m as expected in terms of the particle movement equation.
Takahatake, Yoko; Koma, Yoshikazu
Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05
Yoshimura, Kazuya; Fujiwara, Kenso; Saito, Kimiaki
KEK Proceedings 2016-8, p.67 - 71, 2016/10
This study evaluated the Cs inventory (Bq m) on urban surfaces for eleven buildings and building lots in evacuation zone, and relative Cs inventory was obtained by dividing with the initial inventory on plane permeable field around the studied building. The relative Cs inventory was highest at plane permeable field (0.92), followed by paved ground (0.28) on January 13, 2015. Other surfaces such as roof, wall and window showed obviously small values less than 0.1, indicating that the contamination level of buildings was limited four years after the Fukushima Dai-ichi Nuclear Power Plant accident. Roof and paved ground showed different relative Cs inventories from those in the case of Europe after the Chernobyl Nuclear Power Plant accident, suggesting the importance of local parameterization considering the factors affects to the variation of relative Cs inventory.
Oikawa, Kenichi; Maekawa, Fujio; Tamura, Masaya; Harada, Masahide; Kato, Takashi; Ikeda, Yujiro; Niita, Koji*
LA-UR-06-3904, Vol.2, p.139 - 145, 2006/06
A preliminary investigation on a satellite building for a long-beamline instrument of MLF is now in progress. In order to estimate the total cost of the building, we started the shielding analysis of the beamline using MCNPX and PHITS, where the latest beamline design and the neutron spectrum have been adopted.
Tachibana, Mitsuo; Ito, Hirokuni*; Hatakeyama, Mutsuo*; Yanagihara, Satoshi
Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(1), p.120 - 127, 2004/03
The RAPID-1600 was developed to measure a low-level radioactive contamination on building surfaces automatically. The double layered detectors are structured by two gas flow type detectors with a rays shielding plate between the two detectors and it is horizontally positioned. The lower counter measures and rays and the upper counter measures rays. The rays counting rates are derived by subtracting rays counting rates of the upper counter from and rays counting rates of the lower counter. This mechanism results in sensitive to rays against to low background radiation conditions. The driving unit can move omnidirectionally by controlling two driving wheels individually, and has a capability to correct its position if an orbital error is detected by the self-position identification system. The RAPID-1600 was successfully applied to the actual measurement in the radioisotope production facilities. The RAPID-1600 is expected to be a useful tool for measurement of radioactivity in decommissioning nuclear facilities.
Dekomisshoningu Giho, (26), p.2 - 12, 2002/11
The concept of clearance has been introduced by the International Atomic Energy Agency in 1996 and is very useful for the management of very low-level solid materials generating from the decommissioning of nuclear facilities. Therefore, the European Commission (EC) derived the specific clearance levels for metals, buildings and building rubble in RP 89 and 113, respectively. The EC also derived the general clearance levels for all solid materials generating from the regulated facilities in RP 122. Comparing the clearance levels of Japan with the unrounded levels of EC, the differences of levels are small. The biggest difference is found in Fe-55 and the EC's clearance level is about one fifth of Japanese clearance level. This is caused because the EC considers the direct ingestion of cleared building rubble by children and used the conservative ingestion rate of it. EC's discussions related to the clearance levels are very useful for Japan to derive our own clearance levels and to clear materials from regulatory control.
Saito, Kimiaki; Sakamoto, Ryuichi; Nagaoka, Toshi; Tsutsumi, Masahiro; Moriuchi, Shigeru*
Radiation Protection Dosimetry, 69(1), p.61 - 67, 1997/00
no abstracts in English
Watanabe, Hiromasa; Tanaka, Susumu;
Hoken Butsuri, 26, p.395 - 404, 1991/00
no abstracts in English
Iino, Mari*; Onuma, Susumu*; Hirose, Yukio*; Osawa, Hideaki; Otomo, Shoji*
no journal, ,
This presentation introduces the results of scenario investigation regarding effect compensation on public acceptance of NIMBY facility.
Rodriguez, P.; Suzuki, Mitsutoshi; Hanai, Tasuku
no journal, ,
Capacity-building is an important area, to be continually reinforced in order to maintain the successful operation of an entity or organization. The depletion of capable human resources due to retirement, ill-health and other unavoidable conditions should be addressed. Valuable knowledge and experience should be shared in a certain way; with ease of comprehension and information retention. Virtual reality (VR) is one tool that can be used in response to the urgent need to capture knowledge and experience from relevant resources. In 2016, the Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN) of the Japan Atomic Energy Agency (JAEA) invested in virtual reality knowledge management technology to equip its Center of Excellence. The ISCN has developed a VR system that provides a three-dimensional computer-generated training environment, which can be explored and interacted with by an individual. Through this VR system, the participant becomes part of a virtual world, immersed within the environment. While there, the individual is able to manipulate objects or perform a series of actions. This paper describes how virtual reality is being used by the ISCN as an effective capacity-building tool. It will also describe the approach to how the knowledge and experience for a specific subject matter are conveyed through the use of virtual reality. The effectiveness of the tool has been demonstrated since its introduction through application on several occasions within the training course for the State System of Accounting for and Control of Nuclear Material (SSAC). Use of the VR tool brings benefits from zero exposure to radiation within a suitable environment for the participants' training, whilst enabling the learning of safeguards concepts and associated nuclear material verification measures.
Nitta, Ayako; Hinai, Hiroshi; Shibata, Atsuhiro; Nomura, Kazunori; Oki, Keiichi; Koma, Yoshikazu
no journal, ,
Kawakubo, Yoko; Sekine, Megumi; Noro, Naoko; Inoue, Naoko; Naoi, Yosuke
no journal, ,
Ichihara, Yoshitaka*; Nakamura, Naohiro*; Nabeshima, Kunihiko*; Choi, B.; Nishida, Akemi
no journal, ,
This study aims to evaluate the applicability of the equivalent linear analysis method for reinforced concrete, which uses frequency-independent hysteretic damping, to the seismic design of reactor building of the nuclear power plant. To achieve this, we performed three-dimensional FEM analyses of the soil-structure interaction system, focusing on the nonlinear and equivalent linear seismic behavior of a reactor building under an ideal soil condition. From these results, the method of equivalent analysis showed generally good correspondence with the method of the nonlinear analysis, confirming the effectiveness. Moreover, the method tended to lower the structural stiffness compared to the nonlinear analysis model. Therefore, in the evaluation of the maximum shear strain, we consider that the results were more likely to be higher than the results of nonlinear analysis. In this presentation, we describe the effectiveness and problems of the equivalent linear analysis method using three-dimensional FEM analysis of the soil-structure interaction system.