Temporal variability of Cs concentrations in coastal sediments off Fukushima

Suzuki, Shotaro*; Amano, Yosuke*; Enomoto, Masahiro*; Matsumoto, Akira*; Morioka, Yoshiaki*; Sakuma, Kazuyuki; Tsuruta, Tadahiko; Kaeriyama, Hideki*; Miura, Hikaru*; Tsumune, Daisuke*; et al.

Science of the Total Environment, 831, p.154670_1 - 154670_15, 2022/07

https://doi.org/10.1016/j.scitotenv.2022.154670

Holding force tests of Curie Point Electro-Magnet in hot gas for passive shutdown system

Matsunaga, Shoko*; Matsubara, Shinichiro*; Kato, Atsushi; Yamano, Hidemasa; Dderlein, C.*; Guillemin, E.*; Hirn, J.*

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05

This paper presents a design of Curie Point Electro-Magnet (CPEM) which will be installed as a passive shutdown system for a French Sodium-cooled Fast Reactor (ASTRID) development program which is conducted in collaboration between France and Japan. To confirm CPEM design validity, a qualification program for CPEM is developed on the basis of past comprehensive test series of Self-Actuated Shutdown System (SASS) in Japan. The main outcome of this paper is results of holding force tests in hot gas, which satisfy design requirements. Moreover, the result of a numerical magnetic field analysis showed the same tendency as that of the holding force test.

Safety evaluation of self actuated shutdown system for Gen-IV SFR

Saito, Hiroyuki*; Yamada, Yumi*; Oyama, Kazuhiro*; Matsunaga, Shoko*; Yamano, Hidemasa; Kubo, Shigenobu

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 10 Pages, 2017/04

A self-actuated shutdown system (SASS) is a passive device, which can detach a control rod for reactor shutdown in response to excessive increase in coolant temperature. Since a detachment temperature, which triggers release of a control rod, and a response time are identified as important parameters for validity analyses, this study focused on investigation of the response time and the detachment temperature, and safety analysis to see feasibility of the SASS in low power. For this purpose, design modifications were made to shorten the response time and three-dimensional thermal-hydraulic analysis in a low power operation was carried out in order to confirm the response time. The resulting detachment temperature level is lower than previous studies, leading to improved safety parameters. Based on improved parameters, a safety analysis to see feasibility of the SASS in low power was carried out. From this safety evaluation, it was confirmed that core damage can be prevented by the SASS with flow collector in the case of LOF type ATWS event.

An Investigation on debris bed self-leveling behavior with non-spherical particles

Cheng, S.; Tagami, Hirotaka; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Takeda, Shohei*; Nishi, Shimpei*; Nishikido, Tatsuya*; Zhang, B.*; Matsumoto, Tatsuya*; et al.

Journal of Nuclear Science and Technology, 51(9), p.1096 - 1106, 2014/09

AA2013-0303.pdf:1.68MB

https://doi.org/10.1080/00223131.2014.910478

The Investigation related to the study on the method to withdraw the in-vessel transfer machine; Observation of the structure in the reactor vessel of the fast breeder reactor Monju

Harigae, Hitoshi; Takagi, Tsuyohiko; Hamano, Tomoharu; Nakamura, Shoichi; Oba, Toshio; Ebashi, Masaaki; Okuda, Eiichi; Kinoshita, Tomonobu

JAEA-Technology 2013-014, 150 Pages, 2013/07

JAEA-Technology-2013-014.pdf:24.38MB

In-Vessel Transfer Machine (IVTM) came off from the gripper claw in the Auxiliary Handling Machine (AHM) and fell at a height of approximately two meters during a withdrawal work of the IVTM in the Fast Breeder Reactor (FBR) Monju. The withdrawal work of IVTM from the reactor vessel by AHM was performed. The work, however, was suspended due to the excessive load alarm. To grasp the situation of the IVTM fall, observation of the machine was necessary. An interior observation and an exterior observation of the dropped IVTM were performed. As a result of these observations, the radially deformed lower end of the upper guide tube was observed at the connection part, and it was jammed in the fuel throat sleeve when the dropped IVTM was withdrawn. Based on this information, the IVTM could be safely withdrawn from the reactor vessel with the fuel throat sleeve.

Production of mutants by ion beam irradiation in spp.

Uyama, Yoshihide*; Oya, Hirotaka*; Amano, Yoshinori*; Kashimoto, Koichi*; Hatano, Shoji*; Nozawa, Shigeki; Yoshihara, Ryohei*; Hase, Yoshihiro; Narumi, Issei

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 102, 2013/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2012-046.pdf

Safety design approach for a large-scale Japan Sodium-cooled Fast Reactor (JSFR)

Kotake, Shoji*; Yamano, Hidemasa; Sagayama, Yutaka

Fusion Science and Technology, 61(1T), p.137 - 143, 2012/01

https://doi.org/10.13182/FST12-A13410

The present paper describes safety goals and principles for Generation IV energy systems, with emphasis on prevention and mitigation against severe accidents in the safety design corresponding to Level 4 of the defense-indepth architecture. Consistent with them, a deterministic safety design approach has been applied to the Japan Sodium-cooled Fast Reactor (JSFR) with the complimentary use of probabilistic approach. The JSFR safety design principle has also been developed with safety design features corresponding to essential safety functions, such as reactor shutdown, decay heat removal and containment. Design principle against chemical activity of sodium is also discussed both on the isolation from the reactor core safety and the contribution to the plant reliability.

Fault zone determination and bedrock classification through multivariate analysis; Case study using a dataset from a deep borehole in the Mizunami Underground Research Laboratory

Abumi, Kensho*; Amano, Kenji; Koike, Katsuaki*; Tsuruta, Tadahiko; Matsuoka, Toshiyuki

Joho Chishitsu, 22(4), p.171 - 188, 2011/12

https://doi.org/10.6010/geoinformatics.22.171

Fault zones are treated as essential elements for evaluating the underground geological environment and the engineering performance of rocks. Because of the limitations to borehole investigations, it is not always possible to obtain sufficient, high-quality geological data. In addition, the evaluation of results may differ depending on various factors such as geological conditions and skill of the engineer. Such uncertainty can lead to difficulty in evaluation and understanding of the geological environment at depths and in the decision-making and planning of underground construction, which, as a result, may increases potential risks during construction. To reduce the uncertainty, this study proposes a correct selection method of data item for multivariable analyses composed of principal component analysis and clustering method using a deep borehole data. Utilizing this method and the analyses, the rocks could be accurately classified depending upon their geological characteristics.

Several-MeV -ray generation at NewSUBARU by laser Compton backscattering

Amano, Sho*; Horikawa, Ken*; Ishihara, Kazuki*; Miyamoto, Shuji*; Hayakawa, Takehito; Shizuma, Toshiyuki; Mochizuki, Takayasu*

Nuclear Instruments and Methods in Physics Research A, 602(2), p.337 - 341, 2009/04

https://doi.org/10.1016/j.nima.2009.01.010

A new laser Compton ray source in the energy range of several-MeV was developed using a CO laser at the NewSUBARU electron storage ring. When the electron energies were 974, 1220 and 1460 MeV, the maximum ray energies were measured to be 1.72, 2.72, and 3.91 MeV. The luminosity of the rays was 7300 photon/mA/W/s and a flux of 5.810 photon/s was achieved. These performances agreed with calculations. This generation of rays is in a no-loss mode for the storage electrons, and the maximum flux was limited only by the power of the laser.

Study on flow-induced-vibration evaluation of large-diameter pipings in a sodium-cooled fast reactor, 4; Experiments on the 1/10-scale hot leg test facility in Reynolds number of 50000 and 320000

Iwamoto, Yukiharu*; Yasuda, Kazunori*; Sogo, Motosuke*; Yamano, Hidemasa; Kotake, Shoji

Proceedings of 6th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-6) (USB Flash Drive), 6 Pages, 2008/11

Pressure measurement, laser Doppler velocimetry (LDV) and flow visualization were carried out using the 1/10-scale model of a hot leg piping installed in a Japanese sodium-cooled fast breeder reactor. LDV measurement with Reynolds number of 50000 showed the following results: (1) A flow separation was confirmed in the region between 45 degrees from the elbow inlet and 0.3 times of pipe diameter downstream of the elbow. (2) There appeared two kinds of fluctuations in the present study. In the case of Reynolds number of 320000, it was found that the height of the flow separation downstream of the elbow became smaller, since the inertia of the flow became superior to the inverse pressure gradient.