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SGo, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.
Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03
Times Cited Count：4 Percentile：39.45(Physics, Nuclear)Mikami, Satoshi; Tanaka, Hiroyuki*; Matsuda, Hideo*; Sato, Shoji*; Hoshide, Yoshifumi*; Okuda, Naotoshi*; Suzuki, Takeo*; Sakamoto, Ryuichi*; Ando, Masaki; Saito, Kimiaki
Journal of Environmental Radioactivity, 210, p.105941_1 - 105941_12, 2019/12
Times Cited Count：24 Percentile：59.65(Environmental Sciences)The deposition densities of radiocesium and the air dose rates were repeatedly measured in a large number of undisturbed fields within the 80km zone that surrounds the Fukushima Dai-ichi Nuclear Power Plant site between 2011 and 2016, and features of their temporal changes were clarified. The average air dose rate excluding background radiation in this zone decreased to about 20% of the initial value during the period from June 2011 to August 2016, which was essentially a result of the radioactive decay of 
Cs with a half-life of 2.06y. The air dose rate reduction was faster than that expected from the decay of radiocesium by a factor of about two, with most of this reduction being attributed to the penetration of radiocesium into the soil. The average deposition densities of Cs and 
Cs in fields that were not decontaminated were found to have decreased nearly according to their expected radioactive decay, which indicated that the movement of radiocesium in the horizontal direction was relatively small. The effect of decontamination was apparently observed in the measurements of air dose rates and deposition densities. Nominally, the average air dose rates in the measurement locations were reduced by about 20% by decontamination and other human activities, of which accurate quantitative analysis is and continue to be a challenge.
Wakai, Takashi; Machida, Hideo*; Arakawa, Manabu*; Yanagihara, Seiji*; Suzuki, Ryosuke*; Matsubara, Masaaki*
Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 9 Pages, 2018/07
This paper studies crack opening displacement (COD) evaluation methods used in Leak-Before-Break (LBB) assessment of Sodium cooled Fast Reactor (SFR) pipe. For SFR pipe, the continuous leak monitoring will be adopted as an alternative to a volumetric test of the weld joints under conditions that satisfy LBB. The sodium pipes are made of ASME Gr.91 (modified 9Cr-1Mo steel). Thickness of the pipes is small, because the internal pressure is very small. Modified 9Cr-1Mo steel has a relatively large yield stress and small work hardening coefficient comparing to the austenitic stainless steels which are currently used in the conventional plants. In order to assess the LBB behavior of the sodium pipes made of modified 9Cr-1Mo steel, the coolant leak rate from a through wall crack must be estimated properly. Since the leak rate is strongly related to the crack opening displacement (COD), an appropriate COD assessment method must be established to perform LBB assessment. However, COD assessment method applicable for SFR pipes - having thin wall thickness and made of small work hardening material - has not been proposed yet. Thus, a COD assessment method applicable to such a pipe was proposed in this study. In this method, COD was calculated by classifying the components of COD; elastic, local plastic and fully plastic. In addition, the verification of this method was performed by comparing with the results of a series of four-point bending tests using modified 9Cr-1Mo steel pipe having a circumferential through wall notch. As a result, in some cases, COD were over-estimated especially for large cracks. Although the elastic component of COD is still over-estimated for large cracks, leak evaluation from small cracks is much more important in LBB assessment. Therefore, this study recommends that only the elastic component of COD should be adopted in LBB assessment of SFR pipes.
Hirayama, Hideo*; Kondo, Kenjiro*; Suzuki, Seishiro*; Tanimura, Yoshihiko; Iwanaga, Kohei*; Nagata, Hiroshi*
EPJ Web of Conferences, 153, p.08010_1 - 08010_3, 2017/09
Times Cited Count：3 Percentile：82.30(Nuclear Science & Technology)Pulse height distributions were measured using a CdZnTe detector inside a lead collimator to investigate main source producing high dose rates above the shield plugs of Unit 3 at Fukushima Daiichi Nuclear Power Station. It was confirmed that low energy photons are dominant. Concentrations of Cs-137 under 60 cm concrete of the shield plug were estimated to be between 8.1
10
and 5.710
Bq/cm
from the measured peak count rate of 0.662 MeV photons. If Cs-137 was distributed on the surfaces of the gaps of the shied plugs with radius 6 m and with the averaged concentration of 5 points, 2.610 Bq/cm, total amount of Cs-137 is estimated to be 30 PBq.
Terunuma, Akihiro; Mimura, Ryuji; Nagashima, Hisao; Aoyagi, Yoshitaka; Hirokawa, Katsunori*; Uta, Masato; Ishimori, Yuu; Kuwabara, Jun; Okamoto, Hisato; Kimura, Yasuhisa; et al.
JAEA-Review 2016-008, 98 Pages, 2016/07
JAEA-Review-2016-008.pdf:11.73MB
Japan Atomic Energy Agency formulated the plan to achieve the medium-term target in the period of April 2010 to March 2015(hereinafter referred to as "the second medium-term plan"). JAEA determined the plan for the business operations of each year (hereinafter referred to as "the year plan"). This report is that the Sector of Decommissioning and Radioactive Waste Management has summarized the results of the decommissioning technology development and decommissioning of nuclear facilities which were carried out in the second medium-term plan.
Takahashi, Naoki; Yoshinaka, Kazuyuki; Harada, Akio; Yamanaka, Atsushi; Ueno, Takashi; Kurihara, Ryoichi; Suzuki, Soju; Takamatsu, Misao; Maeda, Shigetaka; Iseki, Atsushi; et al.
Nihon Genshiryoku Gakkai Homu Peji (Internet), 64 Pages, 2016/00
no abstracts in English
Wakai, Takashi; Machida, Hideo*; Yoshida, Shinji*; Yanagihara, Seiji*; Suzuki, Ryosuke*; Matsubara, Masaaki*; Enuma, Yasuhiro
Engineering Failure Analysis, 56, p.484 - 500, 2015/10
Times Cited Count：1 Percentile：10.47(Engineering, Mechanical)SGo, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Kobayashi, Motoki*; Kisamori, Keiichi*; Takaki, Motonobu*; Miya, Hiroyuki*; Ota, Shinsuke*; Michimasa, Shinichiro*; Shimoura, Susumu*; et al.
JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06
Tokunaga, Tomonori*; Watanabe, Hideo*; Yoshida, Naoaki*; Nagasaka, Takuya*; Kasada, Ryuta*; Lee, Y.-J.*; Kimura, Akihiko*; Tokitani, Masayuki*; Mitsuhara, Masatoshi*; Hinoki, Tatsuya*; et al.
Journal of Nuclear Materials, 442(1-3), p.S287 - S291, 2013/11
Times Cited Count：17 Percentile：74.44(Materials Science, Multidisciplinary)Iimura, Soshi*; Matsuishi, Satoru*; Miyakawa, Masashi*; Taniguchi, Takashi*; Suzuki, Katsuhiro*; Usui, Hidetomo*; Kuroki, Kazuhiko*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; et al.
Physical Review B, 88(6), p.060501_1 - 060501_5, 2013/08
Times Cited Count：27 Percentile：69.53(Materials Science, Multidisciplinary)Hirayama, Hideo*; Nakashima, Hiroshi; Sanami, Toshiya*; Yamaguchi, Yasuhiro; Sato, Osamu*; Takagi, Shunji*; Suzuki, Toshikazu*; Iwai, Satoshi*
Nihon Genshiryoku Gakkai-Shi ATOMO
, 55(2), p.83 - 96, 2013/02
Since the accident at the Fukushima Daiichi Power Plant, units of radiation doses such as Sv have been frequently reported by newspapers. However, it is not exactly understood even by experts on nuclear engineering that there are two different concepts which are the protection quantity such as the effective dose related to a radiation health risk and the practical quantity such as ambient dose equivalents related to measurements. In this special issue, Radiological Protection Quantity, and Operational Quantity and Radiological Protection Quantity, explain the radiation protection dose system including the protection and practical quantities established by ICRP and ICRU. Relation between Dosimeters used at Fukushima etc. and Radiological Protection Quantity describes a method and its problems to measure radiations from Cs on surface and underground using survey meters and personal dosimeters, and convert the measured values to effective doses.
Miyachi, Hideo*; Araki, Fumiaki*; Suzuki, Yoshio
Kashika Nyumon, 224 Pages, 2013/01
The visualization means "to make an invisible thing an visible thing", and "to make an visible thing an easily understandable thing. Widely, a clock which makes time a visible thing, and a speed meter which makes speed of a car an visible thing are a device of the visualization, however, in this book we introduce the image processing of the simulation result for the purpose of the confirmation, evaluation, and transmission of the simulation result. In this book we carefully explain the PC environment and the data conversion process for visualizatoin, the basic knowledge about computer graphics, the setting of visualization methods and their parameters, a role of the visualization in the numerical simulation, and a way of thinking of the visualization in the presentation.
Sn cables for ITER toroidal field coilsIsono, Takaaki; Tsutsumi, Fumiaki; Nunoya, Yoshihiko; Matsui, Kunihiro; Takahashi, Yoshikazu; Nakajima, Hideo; Ishibashi, Tatsuji*; Sato, Go*; Chida, Keiji*; Suzuki, Rikio*; et al.
Teion Kogaku, 47(3), p.147 - 152, 2012/03
no abstracts in English
Kimura, Hideo; Aoyagi, Tetsuo; Sato, Taiichi; Sakai, Manabu; Hikasa, Naoki*; Suzuki, Hitoshi; Tsuji, Minoru
JAEA-Technology 2011-027, 31 Pages, 2011/09
JAEA-Technology-2011-027.pdf:2.16MB
The financial accounting and contract management system of JAEA, built on a commercial ERP package, had suffered from serious problems of high lifecycle cost, poor response, and lack of extensibility, due to the too much customization to the ERP package, and disorganized software structure. To solve those problems, three approaches were applied; (1) conducting thorough analysis of business flow and fit/gap, which enabled removing all customization brought to the ERP package; (2) dividing the system into subsystems, and clearly defining interfaces between the subsystems, which increases the transparency, extensibility and performance of the system; (3) outsourcing the development of the subsystems to multiple venders to reduce the development cost. Those approaches can be useful for developing business information systems using commercial software to save time and cost, while meeting the unique requirements of an organization.
Sn cable-in-conduit conductorsHemmi, Tsutomu; Harjo, S.; Ito, Takayoshi; Matsui, Kunihiro; Nunoya, Yoshihiko; Koizumi, Norikiyo; Takahashi, Yoshikazu; Nakajima, Hideo; Aizawa, Kazuya; Suzuki, Hiroshi; et al.
IEEE Transactions on Applied Superconductivity, 21(3), p.2028 - 2031, 2011/06
Times Cited Count：10 Percentile：48.28(Engineering, Electrical & Electronic)Residual strain in conductors is caused by the difference in the coefficient of expansion between NbSn strands and the jacket over a temperature range of 5 - 923 K. The superconducting properties of strands vary significantly, depending on the strain. It is important to clarify the residual strain as part of the evaluation of superconducting performance. However, the residual strain of strands in the conductor has not been measured so far because of their complicated configuration and their location in a jacket. The engineering materials diffractometer "Takumi" in J-PARC can measure residual strain with a relative accuracy of around 0.02%, using neutron diffraction. In this study, the Takumi was applied to the measurement of residual strain in strands for the ITER TF conductor. Results indicate that the residual strain of strands in the conductor can be determined, thereby clarifying the mechanism of residual strain and its relationship to superconducting performance.
Suzuki, Mitsuhiro; Nakamura, Hideo
Journal of Nuclear Science and Technology, 47(12), p.1193 - 1205, 2010/12
Times Cited Count：2 Percentile：16.16(Nuclear Science & Technology)Presented in the paper are experimental results on general performance of core exit thermocouple (CET) to detect core overheat for accident management (AM) action. Thirteen tests simulating small break loss-of-coolant accident (SBLOCA) and abnormal transient are studied by using the Large Scale Test Facility (LSTF) which is a full-height, full-pressure and 1/48 volumetric-scaled PWR model. Clarified are as follows, (1) general CET performance with certain delay in time and temperature rise from core overheating in most cases, (2) one common reason of the delay due to cooling effects of metal structures in core and core exit, (3) an indication of superheat instead of its temperature necessary for significantly high or low pressure transients, (4) no CET heat-up in case of large water fall-back from hot legs and in addition, discussion on applicability to PWR is presented.
Suzuki, Mitsuhiro; Takeda, Takeshi; Nakamura, Hideo
JAEA-Research 2009-057, 188 Pages, 2010/02
JAEA-Research-2009-057.pdf:16.46MB
A series of break size parameter tests (SB-PV-07 and SB-PV-08) were conducted at the Large Scale Test Facility of ROSA-V Program to have an insight into effects of accident management action on core cooling during a simulated vessel top break loss-of-coolant accident with a total failure assumption on the high pressure injection (HPI) system at a pressurized water reactor (PWR). Typical phenomena of vessel top break with break sizes between 1.0 and 0.1% cold leg break equivalent were clarified including upper head water level transients related to steam discharge, coolant mass inventory related to core heat-up, performance of core exit thermocouple (CET)and three-dimensional steam flows in core and core exit. Both operator actions of HPI recovery in the 1.0% top break and steam generator depressurization in the 0.1% top break resulted in immediate recovery of core cooling when these were initiated by CET heat-up at 623 K.
Suzuki, Mitsuhiro; Nakamura, Hideo
Proceedings of 13th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-13) (CD-ROM), 17 Pages, 2009/09
Presented are experiment results on performance of core exit thermocouple (CET) and applicability to PWR accident management (AM) during 12 tests of small-break loss-of-coolant accident (SBLOCA) and abnormal transient conducted at the Large Scale Test Facility (LSTF) of Japan Atomic Energy Agency, which is the largest PWR simulator with full-height and 1/48 volume scaling. General CET performances are derived including (1) CETs are capable in most cases to detect core overheating with delay of time and temperature increase from core heat-up, (2) one of the reasons of this delay is attributed to cooling effects of structural materials at the core exit and peripheral region, (3) CETs were incapable to detect core overheating in a very small break under steam generator depressurization action as well as a 10% cold leg break due to significant water fall-back from hot legs, and (4) an alternative indication by CET superheat is necessary in extremely high and low pressure conditions.
Sugiyama, Tomoyuki; Umeda, Miki; Udagawa, Yutaka; Sasajima, Hideo; Suzuki, Motoe; Fuketa, Toyoshi
Proceedings of OECD/NEA Workshop on Nuclear Fuel Behaviour during Reactivity Initiated Accidents (CD-ROM), 12 Pages, 2009/09
Sugiyama, Tomoyuki; Umeda, Miki; Sasajima, Hideo; Suzuki, Motoe; Fuketa, Toyoshi
Proceedings of Top Fuel 2009 (DVD-ROM), p.489 - 496, 2009/09
