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Nemoto, Miho*; Ebine, Noriya; Okamoto, Akiko; Hosaka, Yasuhisa*; Tsuzuki, Katsunori; Terada, Hiroaki; Hayakawa, Tsuyoshi; Togawa, Orihiko
JAEA-Technology 2021-013, 41 Pages, 2021/08
JAEA-Technology-2021-013.pdf:2.52MB
When North Korea has carried out nuclear tests, Nuclear Emergency Assistance and Training Center (NEAT) predicts atmospheric dispersion of radionuclides by using the WSPEEDI-II upon requests from Nuclear Regulation Authority (NRA) and submits the predicted results to NRA in cooperation with Nuclear Science and Engineering Center (NSEC). This is a part of the activity of NEAT supporting the Japanese Government in emergency responses. The WSPEEDI-II automatic calculation system specialized for responses to nuclear tests by North Korea was developed by NSEC and was used for responses to three nuclear tests from February 2013 to September 2017. This report describes the transfer and installation of the calculation system to NEAT, and the subsequent maintenance and operation. Future issues for responses to nuclear tests are also described in this report.
Sakakibara, Hiroshi; Aoki, Nobuhiro; Muto, Masahiro; Otabe, Jun; Takahashi, Kenji*; Fujita, Naoyuki*; Hiyama, Kazuhiko*; Suzuki, Hirokazu*; Kamogawa, Toshiyuki*; Yokosuka, Toru*; et al.
JAEA-Technology 2020-020, 73 Pages, 2021/03
JAEA-Technology-2020-020.pdf:8.26MB
The decommissioning is currently in progress at the prototype fast breeder reactor Monju. Fuel assemblies will be taken out of its core for the first step of the great task. Fuel assemblies stand on their own spike plugged into a socket on the core support plate and support with adjacent assemblies through their housing pads each other, resulting in steady core structure. For this reason, some substitutive assemblies are necessary for the purpose of discharging the fuel assemblies of the core. Monju side commissioned, therefore, Plutonium Fuel Development Center to manufacture the substitutive assemblies and the Center accepted it. This report gives descriptions of design, manufacture, and shipment in regard to the substitutive assemblies.
Otosaka, Shigeyoshi*; Kambayashi, Shota*; Fukuda, Miho*; Tsuruta, Tadahiko; Misono, Toshiharu; Suzuki, Takashi; Aono, Tatsuo*
Environmental Science & Technology, 54(21), p.13778 - 13785, 2020/11
Times Cited Count：12 Percentile：54.1(Engineering, Environmental)Concentrations of 
Cs in seawater, seabed sediment, and pore water collected from the area around Fukushima were investigated from 2015 to 2018, and the potential of coastal sediments to supply radiocesium to the bottom environment was evaluated. The Cs concentration in the pore water ranged from 33 to 1934 mBq L
and was 10-40 times higher than that in the overlying water (seawater overlying within 30 cm on the seabed). At most stations, the Cs concentrations in the overlying water and the pore water were approximately proportional to those in the sediment. The conditional partition coefficient between pore water and sediment was 0.9-14
10
L kg, independent of the year of sampling. These results indicated that an equilibrium of Cs between pore water and sediment has established in a relatively short period, and Cs in the pore water is gradually exported to seawater near the seabed. A simple box model estimation based on these results showed that the Cs in the sediment was decreased by about 6% per year by desorption/diffusion of Cs from the seabed.
Saito, Shigeru; Suzuki, Kazuhiro; Hatakeyama, Yuichi; Suzuki, Miho; Dai, Y.*
Journal of Nuclear Materials, 534, p.152146_1 - 152146_16, 2020/06
Times Cited Count：1 Percentile：12.16(Materials Science, Multidisciplinary)A post-irradiation examination (PIE) was performed on the tensile specimens prepared from the MEGAPIE (MEGAwatt Pilot Experiment) target which were irradiated in flowing lead-bismuth eutectic (LBE). Thicknesses of the specimens were over two times larger than that of the standard specimen. The PIE revealed that the T91 specimens showed a 1.5-2.0 times larger total elongation (TE) compared to the literature values for a specimen with standard t/w (ratio of thickness to width). It could be suggested that the t/w and TE were strongly correlated. Then, we tried to investigate the effects of the t/w on the TE by comparing unirradiated specimens. We found that there was no t/w dependence on the strength and uniform elongation. On the other hand, the TE increases with increasing t/w. Based on the experimental data, we correlated the TE with various specimens t/w to estimate appropriate TE values, including that for the standard specimen.
Miyai, Hiromitsu; Suzuki, Miho; Kanazawa, Hiroyuki
JAEA-Technology 2016-041, 46 Pages, 2017/03
JAEA-Technology-2016-041.pdf:5.54MB
In the Reactor Fuel Examination Facility (RFEF) of Japan Atomic Energy Agency (JAEA), Post Irradiation Examinations (PIEs) have been carried out for a long time in order to verify the reliability and the safety of the nuclear fuels irradiated in nuclear power plants. Samples for the PIEs are small and have various shapes. In order to facilitate the handling of the samples using a manipulator, the several kinds of jigs have been used for PIEs at RFEF those jigs are usually manufactured by machining process. We tried to make the jigs, which is PLA resin, with 3D printer and instead of machining process for the reduction of the manufacturing time and the improvement of the dimensional accuracy of the jig this time. It became clear that the actual dimensions of the jigs manufactured with 3D printer were roughly smaller at the concave section and larger at the convex section compared with the dimensions of the plan. So it is necessary to make a plan for the jigs after consideration of the characteristic of the 3D printer. The jigs can be applied to SEM observation, because the deposition of carbon film onto the jigs was well. And the jigs can be used to for the metallography, because the jigs were applicable without any harmful effects on polishing and etching processes.
Miyai, Hiromitsu; Suzuki, Miho; Kanazawa, Hiroyuki
Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 4 Pages, 2017/00
In the Reactor Fuel Examination Facility (RFEF) of Japan Atomic Energy Agency (JAEA), Post Irradiation Examinations (PIEs) have been carried out for a long time in order to verify the reliability and the safety of the nuclear fuels irradiated in nuclear power plants. Samples for the PIEs are small and have various shapes. In order to facilitate the handling of the samples using a manipulator, the several kinds of jigs have been used for PIEs at RFEF. Those jigs are usually manufactured by machining process. We tried to make the jigs, which is PLA resin, with 3D printer and instead of machining process for the reduction of the manufacturing time and the improvement of the dimensional accuracy of the jig this time. It became clear that the actual dimensions of the jigs manufactured with 3D printer were roughly smaller at the concave section and larger at the convex section compared with the dimensions of the plan. So it is necessary to make a plan for the jigs after consideration of the characteristic of the 3D printer. The jigs can be applied to SEM observation, because the deposition of carbon film onto the jigs was well. And the jigs can be used to for the metallography, because the jigs were applicable without any harmful effects on polishing and etching processes.
Matsui, Hiroki; Suzuki, Miho; Obata, Hiroki; Kanazawa, Hiroyuki
JAEA-Technology 2014-017, 57 Pages, 2014/06
JAEA-Technology-2014-017.pdf:20.43MB
The Reactor Fuel Examination Facility in JAEA has been used for Post Irradiation Examinations to verify the reliability and safety of the nuclear fuels irradiated in commercial reactors. EPMA (Electron Probe Micro Analyzer) has been utilized for the qualitative analysis of the fission product in the fuel pellet and the detailed observation of the oxide layers formed at the inner and outer surfaces of fuel cladding. Commercial EPMAs were remodeled so that the EPMAs can be applied for radioactive samples. Several shields was set in the EPMA to avoid the 
-rays which radiate from a radioactive sample to the proportional counter in the EPMA. It is important to calculate this shielding performance adequately to maintain the precision of analysis. This report describes the results of re-evaluation of the performance of the shields in the EPMAs in the RFEF by using the Particle and Heavy Ion Transport Code System and the examination results of -ray effect to the X-ray spectrum data by using a radioactive sample.
Tomiyama, Shingo*; Matsuo, Shigeaki*; Matsunaga, Kinuko*; Suzuki, Mihoko*
JNC TJ7420 2005-054, 295 Pages, 2004/02
JNC-TJ7420-2005-054.pdf:17.76MB
None
Yokoya, Akinari; Ushigome, Takeshi*; Tauchi, Hiroshi*; Suzuki, Masao*; Tsuruoka, Chizuru*; Noguchi, Miho; Fujii, Kentaro; Shikazono, Naoya; Watanabe, Ritsuko
no journal, ,
In order to clarify the characteristics of DNA damage induced by high LET radiation, the yields of strand breaks and base lesions induced in closed-circular plasmid DNA (pUC18) were measured after exposing to various kinds of radiation (He, Ne and C ions; 2 to 900 keV/
m). Base excision repair enzymes were used to detect oxidative base lesions. The obtained results show that (1) the yield of prompt SSBs does not depend significantly on the LET, (2) whereas the yield of DSBs increases with increasing LET, (3) The yields of isolated nucleobase lesions detected by enzymes decrease drastically with increasing LET and (4) C and Ne ions induce less base lesions than He ions when compared in the same LET region. These results indicate that the yield of cluster of nucleobase lesions, which are less readily processed by the base excision repair proteins, depends not only LET but also ion species irradiated.
Kanari, Yukiko; Noguchi, Miho; Kaminaga, Kiichi; Sakamoto, Yuka; Yokoya, Akinari; Suzuki, Keiji*
no journal, ,
no abstracts in English
Suzuki, Kazuhiro; Toyokawa, Takuya; Motooka, Takafumi; Tsukada, Takashi; Ueno, Fumiyoshi; Terakawa, Yuto; Suzuki, Miho; Ichise, Kenichi; Numata, Masami; Kikuchi, Hiroyuki
no journal, ,
no abstracts in English
Yokoya, Akinari; Narita, Ayumi; Kaminaga, Kiichi; Kanari, Yukiko; Sakamoto, Yuka; Noguchi, Miho; Usami, Noriko*; Kobayashi, Katsumi*; Fujii, Kentaro; Suzuki, Keiji*
no journal, ,
no abstracts in English
Motooka, Takafumi; Suzuki, Miho; Tomita, Takeshi; Kimura, Yasuhiko; Ueno, Fumiyoshi
no journal, ,
To investigate the migration of seawater components to a spent fuel cladding tube, cross-sectional observation for spent fuel cladding tube immersed in diluted artificial seawater at 80 for 300 hours was conducted with EPMA. Spent fuel cladding tube having crud layer and zirconium oxide layer showed the adhesion of seawater components (Mg, Cl) on the cladding and no penetration of seawater components into the cladding.
Kanari, Yukiko; Kaminaga, Kiichi; Sakamoto, Yuka; Narita, Ayumi; Noguchi, Miho; Usami, Noriko*; Kobayashi, Katsumi*; Suzuki, Keiji*; Yokoya, Akinari; Fujii, Kentaro
no journal, ,
no abstracts in English
Motooka, Takafumi; Suzuki, Kazuhiro; Suzuki, Miho; Toyokawa, Takuya; Kimura, Yasuhiko
no journal, ,
Spent fuels were stored in the spent fuel pool (SFP) at the Fukushima Daiichi Nuclear Power Plant. Seawater was injected into SFP to cool spent fuels for emergency measure in the Fukushima Daiichi Nuclear Accident. Seawater can cause local corrosion. The purpose of this study is to investigate the effect of seawater on corrosion behavior and mechanical property of the spent fuel cladding. We immersed short spent fuel cladding tubes (
50 GWd/t) in artificial seawater at 353 K for 300 h and conducted visual, metallographic and strength examinations of the tubes after immersion. Visual and metallographic examination indicated that warm seawater little affected the corrosion behavior of the spent fuel cladding. Black oxides formed on the surface of the cladding during the reactor operation were observed. No local corrosion and crack were observed. Ultimate tensile strength (UTS) and 0.2% yield strength (0.2%YS) of tubes with and without immersion in artificial seawater at 353 K for 300 h were measured. The strength of immersed tube was comparable to that of non-immersed tube. The results suggest that the seawater injection little affects on corrosion behavior and mechanical property of the spent fuel cladding.
Noguchi, Miho; Yokoya, Akinari; Kaminaga, Kiichi; Fujii, Kentaro; Suzuki, Keiji*; Usami, Noriko*
no journal, ,
Noguchi, Miho; Yokoya, Akinari; Suzuki, Keiji*; Fujii, Kentaro
no journal, ,
Kaminaga, Kiichi; Kanari, Yukiko*; Sakamoto, Yuka*; Noguchi, Miho; Narita, Ayumi*; Fujii, Kentaro; Usami, Noriko*; Kobayashi, Katsumi*; Suzuki, Keiji*; Yokoya, Akinari
no journal, ,
Takano, Masahide; Onozawa, Atsushi; Suzuki, Miho; Obata, Hiroki
no journal, ,
no abstracts in English
Saito, Shigeru; Kikuchi, Kenji*; Suzuki, Kazuhiro; Hatakeyama, Yuichi; Endo, Shinya; Suzuki, Miho; Okubo, Nariaki; Kondo, Keietsu
no journal, ,
The world's first megawatt-class lead-bismuth target, MEGAPIE (MEGAwatt Pilot Experiment), was dismantled and post irradiation examination (PIE) samples were prepared at PSI hot-lab. The samples were shipped to each institutions including JAEA. The samples were cut from the beam window (BW, T91) and the flow guide tube (FGT, SS316L). And all samples are prepared without LBE. The irradiation conditions of the specimens irradiated at SINQ target were as follows: proton energy was 580 MeV, irradiation temperatures were ranged from 251 to 341
C, and displacement damage levels were ranged from 0.16 to 1.57 dpa. PIE including SP (small punch) and three point bending tests were performed. SP tests were executed for T91 and SS316L specimens at R.T. in air condition. Specimen size for SP test with 2.4 mm steel-ball is 8 mm 8 mm 0.5 mm. T91 specimens were cut from the Spitze (triangle) sample and polished to thickness of 0.5 mm. The OM/SP specimens of SS316L were polished to thickness of 0.5 mm. Three point bending tests were executed for SS316L specimens at R.T. in air condition. The bend bar specimens of SS316L without notch were employed. Results of the SP tests and three point bending tests on the irradiated specimens will be presented at the workshop. Cross sectional observation on the Spitze sample and microstructural observation by TEM will be also reported.
