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Endo, Akira
Annals of the ICRP, 52(4), p.5 - 7, 2024/12
In its Publication 155, International Commission on Radiological Protection (ICRP) has developed data on the Specific Absorbed Fraction (SAF) for reference males and females at ages of newborn, 1 year, 5 years, 10 years, and 15 years. The SAF represents the fraction of energy emitted within a source region which is absorbed in a target region per mass of the target region and is essential for calculating absorbed doses in organs or tissues for internal exposure. By combining the data of Publication 155 with the SAF data for reference adult males and females already published as Publication 133, an SAF dataset for the calculation of age-dependent dose coefficients for members of the public for environmental intakes of radionuclides has been completed. This, together with revised biokinetic models and nuclear decay data, means that the key building blocks for calculating new dose coefficients are in place. The outcome will soon be available in a series of ICRP Publications of Dose Coefficients for Intakes of Radionuclides by Members of the Public.
Li, S.; Yamaguchi, Yoshihito; Katsuyama, Jinya; Li, Y.
Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 8 Pages, 2024/07
Kawaguchi, Munemichi; Hirakawa, Yasushi; Sugita, Yusuke; Yamaguchi, Yutaka
Nuclear Technology, 210(1), p.55 - 71, 2024/01
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)This study has developed an estimation method for residual sodium film and sodium lumps on dummy fuel pins in Monju and demonstrated sodium draining behavior through gaps among the pins, experimentally. The amounts of the residual sodium on the surface of the pins were measured using the three-type test specimens: (a) single pin, (b) 7-pin assembly, and (c) 169-pin assembly. The experiments revealed that the withdrawal speed of the pins and improvement of the sodium wetting increased drastically the amounts of the residual sodium. Furthermore, the experiments using the 169-pin assembly measured the practical amounts of the residual sodium in the dummy fuel assembly of short length and demonstrated sodium draining behavior through the dummy fuel assembly. The estimation method includes four models: a viscosity flow model, Landau-Levich-Derjaguin (LLD) model, an empirical equation related to the Bretherton model, and a capillary force model in a tube. The calculation predicted comparable amounts of the residual sodium with the experiments. An uncertain of the sodium wetting effects were close to 1.8 times the estimation values of the LLD model. With this estimation method, the amounts of the residual sodium on the unloaded Monju dummy fuel assembly can be evaluated.
Li, S.; Yamaguchi, Yoshihito; Katsuyama, Jinya; Li, Y.; Deng, D.*
Proceedings of ASME 2023 Pressure Vessels and Piping Conference (PVP 2023) (Internet), 7 Pages, 2023/07
Suzuki, Kenji*; Miura, Yasufumi*; Shiro, Ayumi*; Toyokawa, Hidenori*; Saji, Choji*; Shobu, Takahisa; Morooka, Satoshi
Zairyo, 72(4), p.316 - 323, 2023/04
Saha, P. K.; Okabe, Kota; Nakanoya, Takamitsu; Shobuda, Yoshihiro; Harada, Hiroyuki; Tamura, Fumihiko; Okita, Hidefumi; Yoshimoto, Masahiro; Hotchi, Hideaki*
Journal of Physics; Conference Series, 2420, p.012040_1 - 012040_7, 2023/01
Yamashita, Takayuki*; Koga, Norimitsu*; Kawasaki, Takuro; Morooka, Satoshi; Tomono, Shohei*; Umezawa, Osamu*; Harjo, S.
Materials Science & Engineering A, 819, p.141509_1 - 141509_10, 2021/07
Times Cited Count:29 Percentile:87.97(Nanoscience & Nanotechnology)Nishida, Satoru*; Nishino, Soichiro*; Sekine, Masahiko*; Oka, Yuki*; Harjo, S.; Kawasaki, Takuro; Suzuki, Hiroshi; Morii, Yukio*; Ishii, Yoshinobu*
Materials Transactions, 62(5), p.667 - 674, 2021/05
Times Cited Count:5 Percentile:30.58(Materials Science, Multidisciplinary)Suzuki, Tamaki*; Okawa, Teppei*; Harjo, S.; Sasaki, Toshihiko*
Nihon Kikai Gakkai Rombunshu (Internet), 87(894), p.20-00377_1 - 20-00377_15, 2021/02
Su, Y. H.; Oikawa, Kenichi; Shinohara, Takenao; Kai, Tetsuya; Horino, Takashi*; Idohara, Osamu*; Misaka, Yoshitaka*; Tomota, Yo*
Scientific Reports (Internet), 11, p.4155_1 - 4155_14, 2021/02
Times Cited Count:23 Percentile:75.61(Multidisciplinary Sciences)Hayashi, Makoto*; Shobu, Takahisa
Residual Stress, p.100 - 132, 2021/00
Structural materials may undergo fatigue fracture or stress corrosion cracking during use. One of the causes is the residual stress generated by heat treatment and processing in the manufacturing process of structural materials. There are various methods for measuring the residual stress. This book introduces measurement techniques using ultrasonic and magnetic methods, starting with laboratory X-rays, synchrotron radiation X-rays, and neutrons. In addition, we will outline examples of measurement of residual stress due to processing and welding of various materials, measurement examples of actual machines, change behavior of residual stress due to static and repeated loads, and evaluation methods of fatigue remaining life based on the change behavior.
Hayashi, Makoto*; Okido, Shinobu*; Suzuki, Hiroshi
Quantum Beam Science (Internet), 4(2), p.18_1 - 18_12, 2020/06
Harjo, S.; Kawasaki, Takuro; Grazzi, F.*; Shinohara, Takenao; Tanaka, Manako*
Materialia, 7, p.100377_1 - 100377_9, 2019/09
Shimada, Kazumasa; Sasaki, Toshihisa*; Iijima, Masashi*; Munakata, Masahiro
JAEA-Research 2018-012, 68 Pages, 2019/02
The external exposure dose of off-site emergency responders at Fukushima Dai-ichi Nuclear Power Station accident were evaluated in order to consider a radiation protection of emergency responders. The maximum value of individual daily dose of emergency responders whose activities details were recorded from 12th to 31th March 2011 was 650 Sv engaged in evacuation support in Futaba Town on 12th. Next, atmospheric concentrations and deposition of radionuclides were calculated from the source terms estimated by previous studies using atmospheric diffusion and deposit calculation codes, and air dose rates at off-site were estimated. Then, the external exposure dose was calculated for 6 emergency responders whose daily activities and personal doses were continuously recorded. Furthermore, the maximum value and the average value of the calculation external dose of emergency responders in the activity area were compared with the measurement value of the personal dosimeter of them. These results showed that the calculated value of the external exposure dose of emergency responders calculated from the maximum value of the dose rate in the active area roughly includes the measured value.
Suzuki, Kenji*; Shobu, Takahisa
E-Journal of Advanced Maintenance (Internet), 10(4), p.9 - 17, 2019/02
In materials with an elastic anisotropy, a stress difference is generated between crystals when plastic deformation occurs, and it is known that this is deeply involved in material fracture. In this study, the residual stress for load direction in the plastically deformed material was investigated for each crystal orientation using the high-energy synchrotron radiation diffraction method. As a result, it was found that the residual stress is a tensile residual stress at an index with a high X-ray elastic constant (Young's modulus obtained for each diffraction surface) and a compressive residual stress at an index with a low X-ray elastic constant. We believe that this result will be useful for the technique of controlling the crystal orientation like the texture as improving the material strength.
Yamamoto, Kazami
EPJ Web of Conferences, 153, p.07022_1 - 07022_6, 2017/09
Times Cited Count:1 Percentile:59.20(Nuclear Science & Technology)The J-PARC 3 GeV Rapid Cycling Synchrotron (RCS) delivers a 1-MW, high-intensity beam to the following facilities. In such high-intensity accelerator, the operational beam intensity is limited to keep the exposure to the workers by the residual dose within acceptable tolerances. Therefore we continue to commission the accelerator system to reduce the beam loss. In order to achieve further high-intensity operation, the J-PARC accelerator system was drastically upgraded (Increment of the injection energy of RCS and peak current of Linac) over the past two years. After the upgrade, the beam loss was decreased by the commissioning. The output power was increased; nevertheless the residual doses were kept same level or decreased. Since we replaced the broken collimator which was higher activated, we kept the exposure to the workers within acceptable level.
Honda, Yuki; Inaba, Yoshitomo; Nakagawa, Shigeaki; Yamazaki, Kazunori; Kobayashi, Shoichi; Aono, Tetsuya; Shibata, Taiju; Ishitsuka, Etsuo
JAEA-Technology 2017-013, 20 Pages, 2017/06
Decay heat is one of an important factor for a safety evaluation of depressurized loss-of-forced cooling accident, a representative high consequence accident, in high temperature gas-cooled reactor (HTGR). Traditionally, a conservative decay heat curve is used for safety analysis according to the regulatory standards. On the other hand, there is growing interest in obtaining test data related to decay heat for the use of uncertainty analysis. However, such data has not been obtained for prismatic-type HTGR. Therefore, we have launched a test program to obtain the decay heat data from the HTTR. As an initial step, an applicability confirmation test of decay heat evaluation method for HTGR was conducted in February 2017 without non-nuclear heating condition. This report introduces an estimation method for the decay heat based on test data using HTTR and shows the results of validation of the reactor residual heat evaluation method which will be used to obtain the decay heat data based on test data.
Akita, Koichi; Shibahara, Masakazu*; Ikushima, Kazuki*; Nishikawa, Satoru*; Furukawa, Takashi*; Suzuki, Hiroshi; Harjo, S.; Kawasaki, Takuro; Vladimir, L.*
Yosetsu Gakkai Rombunshu (Internet), 35(2), p.112s - 116s, 2017/06
Ikushima, Kazuki*; Kitani, Yuji*; Shibahara, Masakazu*; Nishikawa, Satoru*; Furukawa, Takashi*; Akita, Koichi; Suzuki, Hiroshi; Morooka, Satoshi
Yosetsu Gakkai Rombunshu (Internet), 35(2), p.75s - 79s, 2017/06
Miyahara, Kaname; Ohara, Toshimasa*
Nihon Genshiryoku Gakkai-Shi ATOMO, 59(5), p.282 - 286, 2017/05
This review highlights JAEA and NIES's challenges for enhancing Fukushima environmental resilience based on carrying out multifaceted research working with many public and private sector organizations and academia.